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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * Implementation of the Transmission Control Protocol(TCP).
7 *
Jesper Juhl02c30a82005-05-05 16:16:16 -07008 * Authors: Ross Biro
Linus Torvalds1da177e2005-04-16 15:20:36 -07009 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
10 * Mark Evans, <evansmp@uhura.aston.ac.uk>
11 * Corey Minyard <wf-rch!minyard@relay.EU.net>
12 * Florian La Roche, <flla@stud.uni-sb.de>
13 * Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
14 * Linus Torvalds, <torvalds@cs.helsinki.fi>
15 * Alan Cox, <gw4pts@gw4pts.ampr.org>
16 * Matthew Dillon, <dillon@apollo.west.oic.com>
17 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
18 * Jorge Cwik, <jorge@laser.satlink.net>
19 */
20
21/*
22 * Changes:
23 * Pedro Roque : Fast Retransmit/Recovery.
24 * Two receive queues.
25 * Retransmit queue handled by TCP.
26 * Better retransmit timer handling.
27 * New congestion avoidance.
28 * Header prediction.
29 * Variable renaming.
30 *
31 * Eric : Fast Retransmit.
32 * Randy Scott : MSS option defines.
33 * Eric Schenk : Fixes to slow start algorithm.
34 * Eric Schenk : Yet another double ACK bug.
35 * Eric Schenk : Delayed ACK bug fixes.
36 * Eric Schenk : Floyd style fast retrans war avoidance.
37 * David S. Miller : Don't allow zero congestion window.
38 * Eric Schenk : Fix retransmitter so that it sends
39 * next packet on ack of previous packet.
40 * Andi Kleen : Moved open_request checking here
41 * and process RSTs for open_requests.
42 * Andi Kleen : Better prune_queue, and other fixes.
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -080043 * Andrey Savochkin: Fix RTT measurements in the presence of
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 * timestamps.
45 * Andrey Savochkin: Check sequence numbers correctly when
46 * removing SACKs due to in sequence incoming
47 * data segments.
48 * Andi Kleen: Make sure we never ack data there is not
49 * enough room for. Also make this condition
50 * a fatal error if it might still happen.
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +090051 * Andi Kleen: Add tcp_measure_rcv_mss to make
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 * connections with MSS<min(MTU,ann. MSS)
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +090053 * work without delayed acks.
Linus Torvalds1da177e2005-04-16 15:20:36 -070054 * Andi Kleen: Process packets with PSH set in the
55 * fast path.
56 * J Hadi Salim: ECN support
57 * Andrei Gurtov,
58 * Pasi Sarolahti,
59 * Panu Kuhlberg: Experimental audit of TCP (re)transmission
60 * engine. Lots of bugs are found.
61 * Pasi Sarolahti: F-RTO for dealing with spurious RTOs
Linus Torvalds1da177e2005-04-16 15:20:36 -070062 */
63
Linus Torvalds1da177e2005-04-16 15:20:36 -070064#include <linux/mm.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090065#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070066#include <linux/module.h>
67#include <linux/sysctl.h>
Ilpo Järvinena0bffff2009-03-21 13:36:17 -070068#include <linux/kernel.h>
Satoru SATOH5ffc02a2008-05-04 22:14:42 -070069#include <net/dst.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070070#include <net/tcp.h>
71#include <net/inet_common.h>
72#include <linux/ipsec.h>
73#include <asm/unaligned.h>
Chris Leech1a2449a2006-05-23 18:05:53 -070074#include <net/netdma.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070075
Brian Haleyab32ea52006-09-22 14:15:41 -070076int sysctl_tcp_timestamps __read_mostly = 1;
77int sysctl_tcp_window_scaling __read_mostly = 1;
78int sysctl_tcp_sack __read_mostly = 1;
79int sysctl_tcp_fack __read_mostly = 1;
80int sysctl_tcp_reordering __read_mostly = TCP_FASTRETRANS_THRESH;
Eric Dumazet4bc2f182010-07-09 21:22:10 +000081EXPORT_SYMBOL(sysctl_tcp_reordering);
Ilpo Järvinen255cac92009-05-04 11:07:36 -070082int sysctl_tcp_ecn __read_mostly = 2;
Eric Dumazet4bc2f182010-07-09 21:22:10 +000083EXPORT_SYMBOL(sysctl_tcp_ecn);
Brian Haleyab32ea52006-09-22 14:15:41 -070084int sysctl_tcp_dsack __read_mostly = 1;
85int sysctl_tcp_app_win __read_mostly = 31;
86int sysctl_tcp_adv_win_scale __read_mostly = 2;
Eric Dumazet4bc2f182010-07-09 21:22:10 +000087EXPORT_SYMBOL(sysctl_tcp_adv_win_scale);
Linus Torvalds1da177e2005-04-16 15:20:36 -070088
Brian Haleyab32ea52006-09-22 14:15:41 -070089int sysctl_tcp_stdurg __read_mostly;
90int sysctl_tcp_rfc1337 __read_mostly;
91int sysctl_tcp_max_orphans __read_mostly = NR_FILE;
Ilpo Järvinenc96fd3d2007-09-20 11:36:37 -070092int sysctl_tcp_frto __read_mostly = 2;
Ilpo Järvinen3cfe3ba2007-02-27 10:09:49 -080093int sysctl_tcp_frto_response __read_mostly;
Brian Haleyab32ea52006-09-22 14:15:41 -070094int sysctl_tcp_nometrics_save __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -070095
Andreas Petlund7e380172010-02-18 04:48:19 +000096int sysctl_tcp_thin_dupack __read_mostly;
97
Brian Haleyab32ea52006-09-22 14:15:41 -070098int sysctl_tcp_moderate_rcvbuf __read_mostly = 1;
99int sysctl_tcp_abc __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101#define FLAG_DATA 0x01 /* Incoming frame contained data. */
102#define FLAG_WIN_UPDATE 0x02 /* Incoming ACK was a window update. */
103#define FLAG_DATA_ACKED 0x04 /* This ACK acknowledged new data. */
104#define FLAG_RETRANS_DATA_ACKED 0x08 /* "" "" some of which was retransmitted. */
105#define FLAG_SYN_ACKED 0x10 /* This ACK acknowledged SYN. */
106#define FLAG_DATA_SACKED 0x20 /* New SACK. */
107#define FLAG_ECE 0x40 /* ECE in this ACK */
108#define FLAG_DATA_LOST 0x80 /* SACK detected data lossage. */
109#define FLAG_SLOWPATH 0x100 /* Do not skip RFC checks for window update.*/
Ilpo Järvinen4dc26652007-02-21 23:16:11 -0800110#define FLAG_ONLY_ORIG_SACKED 0x200 /* SACKs only non-rexmit sent before RTO */
Ilpo Järvinen2e605292007-08-02 19:46:58 -0700111#define FLAG_SND_UNA_ADVANCED 0x400 /* Snd_una was changed (!= FLAG_DATA_ACKED) */
Ryousei Takano564262c12007-10-25 23:03:52 -0700112#define FLAG_DSACKING_ACK 0x800 /* SACK blocks contained D-SACK info */
Ilpo Järvinen009a2e32007-09-20 11:34:38 -0700113#define FLAG_NONHEAD_RETRANS_ACKED 0x1000 /* Non-head rexmitted data was ACKed */
Ilpo Järvinencadbd032007-12-31 04:49:21 -0800114#define FLAG_SACK_RENEGING 0x2000 /* snd_una advanced to a sacked seq */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115
116#define FLAG_ACKED (FLAG_DATA_ACKED|FLAG_SYN_ACKED)
117#define FLAG_NOT_DUP (FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED)
118#define FLAG_CA_ALERT (FLAG_DATA_SACKED|FLAG_ECE)
119#define FLAG_FORWARD_PROGRESS (FLAG_ACKED|FLAG_DATA_SACKED)
Ilpo Järvinen2e605292007-08-02 19:46:58 -0700120#define FLAG_ANY_PROGRESS (FLAG_FORWARD_PROGRESS|FLAG_SND_UNA_ADVANCED)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122#define TCP_REMNANT (TCP_FLAG_FIN|TCP_FLAG_URG|TCP_FLAG_SYN|TCP_FLAG_PSH)
Ilpo Järvinenbdf1ee52007-05-27 02:04:16 -0700123#define TCP_HP_BITS (~(TCP_RESERVED_BITS|TCP_FLAG_PSH))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900125/* Adapt the MSS value used to make delayed ack decision to the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126 * real world.
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900127 */
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800128static void tcp_measure_rcv_mss(struct sock *sk, const struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129{
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700130 struct inet_connection_sock *icsk = inet_csk(sk);
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900131 const unsigned int lss = icsk->icsk_ack.last_seg_size;
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700132 unsigned int len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900134 icsk->icsk_ack.last_seg_size = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135
136 /* skb->len may jitter because of SACKs, even if peer
137 * sends good full-sized frames.
138 */
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800139 len = skb_shinfo(skb)->gso_size ? : skb->len;
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700140 if (len >= icsk->icsk_ack.rcv_mss) {
141 icsk->icsk_ack.rcv_mss = len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 } else {
143 /* Otherwise, we make more careful check taking into account,
144 * that SACKs block is variable.
145 *
146 * "len" is invariant segment length, including TCP header.
147 */
Arnaldo Carvalho de Melo9c702202007-04-25 18:04:18 -0700148 len += skb->data - skb_transport_header(skb);
William Allen Simpsonbee7ca92009-11-10 09:51:18 +0000149 if (len >= TCP_MSS_DEFAULT + sizeof(struct tcphdr) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 /* If PSH is not set, packet should be
151 * full sized, provided peer TCP is not badly broken.
152 * This observation (if it is correct 8)) allows
153 * to handle super-low mtu links fairly.
154 */
155 (len >= TCP_MIN_MSS + sizeof(struct tcphdr) &&
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -0700156 !(tcp_flag_word(tcp_hdr(skb)) & TCP_REMNANT))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157 /* Subtract also invariant (if peer is RFC compliant),
158 * tcp header plus fixed timestamp option length.
159 * Resulting "len" is MSS free of SACK jitter.
160 */
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700161 len -= tcp_sk(sk)->tcp_header_len;
162 icsk->icsk_ack.last_seg_size = len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 if (len == lss) {
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700164 icsk->icsk_ack.rcv_mss = len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 return;
166 }
167 }
Alexey Kuznetsov1ef96962006-09-19 12:52:50 -0700168 if (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)
169 icsk->icsk_ack.pending |= ICSK_ACK_PUSHED2;
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700170 icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171 }
172}
173
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700174static void tcp_incr_quickack(struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175{
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700176 struct inet_connection_sock *icsk = inet_csk(sk);
177 unsigned quickacks = tcp_sk(sk)->rcv_wnd / (2 * icsk->icsk_ack.rcv_mss);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800179 if (quickacks == 0)
180 quickacks = 2;
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700181 if (quickacks > icsk->icsk_ack.quick)
182 icsk->icsk_ack.quick = min(quickacks, TCP_MAX_QUICKACKS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183}
184
stephen hemminger1b9f4092010-09-28 19:30:14 +0000185static void tcp_enter_quickack_mode(struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186{
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700187 struct inet_connection_sock *icsk = inet_csk(sk);
188 tcp_incr_quickack(sk);
189 icsk->icsk_ack.pingpong = 0;
190 icsk->icsk_ack.ato = TCP_ATO_MIN;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191}
192
193/* Send ACKs quickly, if "quick" count is not exhausted
194 * and the session is not interactive.
195 */
196
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700197static inline int tcp_in_quickack_mode(const struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198{
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700199 const struct inet_connection_sock *icsk = inet_csk(sk);
200 return icsk->icsk_ack.quick && !icsk->icsk_ack.pingpong;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201}
202
Ilpo Järvinenbdf1ee52007-05-27 02:04:16 -0700203static inline void TCP_ECN_queue_cwr(struct tcp_sock *tp)
204{
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800205 if (tp->ecn_flags & TCP_ECN_OK)
Ilpo Järvinenbdf1ee52007-05-27 02:04:16 -0700206 tp->ecn_flags |= TCP_ECN_QUEUE_CWR;
207}
208
Eric Dumazetcf533ea2011-10-21 05:22:42 -0400209static inline void TCP_ECN_accept_cwr(struct tcp_sock *tp, const struct sk_buff *skb)
Ilpo Järvinenbdf1ee52007-05-27 02:04:16 -0700210{
211 if (tcp_hdr(skb)->cwr)
212 tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
213}
214
215static inline void TCP_ECN_withdraw_cwr(struct tcp_sock *tp)
216{
217 tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
218}
219
Eric Dumazet7a269ff2011-09-22 20:02:19 +0000220static inline void TCP_ECN_check_ce(struct tcp_sock *tp, const struct sk_buff *skb)
Ilpo Järvinenbdf1ee52007-05-27 02:04:16 -0700221{
Eric Dumazet7a269ff2011-09-22 20:02:19 +0000222 if (!(tp->ecn_flags & TCP_ECN_OK))
223 return;
224
Eric Dumazetb82d1bb2011-09-27 02:20:08 -0400225 switch (TCP_SKB_CB(skb)->ip_dsfield & INET_ECN_MASK) {
Eric Dumazet7a269ff2011-09-22 20:02:19 +0000226 case INET_ECN_NOT_ECT:
Ilpo Järvinenbdf1ee52007-05-27 02:04:16 -0700227 /* Funny extension: if ECT is not set on a segment,
Eric Dumazet7a269ff2011-09-22 20:02:19 +0000228 * and we already seen ECT on a previous segment,
229 * it is probably a retransmit.
230 */
231 if (tp->ecn_flags & TCP_ECN_SEEN)
Ilpo Järvinenbdf1ee52007-05-27 02:04:16 -0700232 tcp_enter_quickack_mode((struct sock *)tp);
Eric Dumazet7a269ff2011-09-22 20:02:19 +0000233 break;
234 case INET_ECN_CE:
235 tp->ecn_flags |= TCP_ECN_DEMAND_CWR;
236 /* fallinto */
237 default:
238 tp->ecn_flags |= TCP_ECN_SEEN;
Ilpo Järvinenbdf1ee52007-05-27 02:04:16 -0700239 }
240}
241
Eric Dumazetcf533ea2011-10-21 05:22:42 -0400242static inline void TCP_ECN_rcv_synack(struct tcp_sock *tp, const struct tcphdr *th)
Ilpo Järvinenbdf1ee52007-05-27 02:04:16 -0700243{
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800244 if ((tp->ecn_flags & TCP_ECN_OK) && (!th->ece || th->cwr))
Ilpo Järvinenbdf1ee52007-05-27 02:04:16 -0700245 tp->ecn_flags &= ~TCP_ECN_OK;
246}
247
Eric Dumazetcf533ea2011-10-21 05:22:42 -0400248static inline void TCP_ECN_rcv_syn(struct tcp_sock *tp, const struct tcphdr *th)
Ilpo Järvinenbdf1ee52007-05-27 02:04:16 -0700249{
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800250 if ((tp->ecn_flags & TCP_ECN_OK) && (!th->ece || !th->cwr))
Ilpo Järvinenbdf1ee52007-05-27 02:04:16 -0700251 tp->ecn_flags &= ~TCP_ECN_OK;
252}
253
Eric Dumazetcf533ea2011-10-21 05:22:42 -0400254static inline int TCP_ECN_rcv_ecn_echo(const struct tcp_sock *tp, const struct tcphdr *th)
Ilpo Järvinenbdf1ee52007-05-27 02:04:16 -0700255{
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800256 if (th->ece && !th->syn && (tp->ecn_flags & TCP_ECN_OK))
Ilpo Järvinenbdf1ee52007-05-27 02:04:16 -0700257 return 1;
258 return 0;
259}
260
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261/* Buffer size and advertised window tuning.
262 *
263 * 1. Tuning sk->sk_sndbuf, when connection enters established state.
264 */
265
266static void tcp_fixup_sndbuf(struct sock *sk)
267{
Eric Dumazet87fb4b72011-10-13 07:28:54 +0000268 int sndmem = SKB_TRUESIZE(tcp_sk(sk)->rx_opt.mss_clamp + MAX_TCP_HEADER);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269
Eric Dumazet06a59ec2011-10-13 18:24:42 +0000270 sndmem *= TCP_INIT_CWND;
271 if (sk->sk_sndbuf < sndmem)
272 sk->sk_sndbuf = min(sndmem, sysctl_tcp_wmem[2]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273}
274
275/* 2. Tuning advertised window (window_clamp, rcv_ssthresh)
276 *
277 * All tcp_full_space() is split to two parts: "network" buffer, allocated
278 * forward and advertised in receiver window (tp->rcv_wnd) and
279 * "application buffer", required to isolate scheduling/application
280 * latencies from network.
281 * window_clamp is maximal advertised window. It can be less than
282 * tcp_full_space(), in this case tcp_full_space() - window_clamp
283 * is reserved for "application" buffer. The less window_clamp is
284 * the smoother our behaviour from viewpoint of network, but the lower
285 * throughput and the higher sensitivity of the connection to losses. 8)
286 *
287 * rcv_ssthresh is more strict window_clamp used at "slow start"
288 * phase to predict further behaviour of this connection.
289 * It is used for two goals:
290 * - to enforce header prediction at sender, even when application
291 * requires some significant "application buffer". It is check #1.
292 * - to prevent pruning of receive queue because of misprediction
293 * of receiver window. Check #2.
294 *
295 * The scheme does not work when sender sends good segments opening
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -0800296 * window and then starts to feed us spaghetti. But it should work
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 * in common situations. Otherwise, we have to rely on queue collapsing.
298 */
299
300/* Slow part of check#2. */
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -0700301static int __tcp_grow_window(const struct sock *sk, const struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302{
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -0700303 struct tcp_sock *tp = tcp_sk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304 /* Optimize this! */
Eric Dumazetdfd4f0a2007-12-21 06:07:53 -0800305 int truesize = tcp_win_from_space(skb->truesize) >> 1;
306 int window = tcp_win_from_space(sysctl_tcp_rmem[2]) >> 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307
308 while (tp->rcv_ssthresh <= window) {
309 if (truesize <= skb->len)
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700310 return 2 * inet_csk(sk)->icsk_ack.rcv_mss;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311
312 truesize >>= 1;
313 window >>= 1;
314 }
315 return 0;
316}
317
Eric Dumazetcf533ea2011-10-21 05:22:42 -0400318static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319{
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -0700320 struct tcp_sock *tp = tcp_sk(sk);
321
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322 /* Check #1 */
323 if (tp->rcv_ssthresh < tp->window_clamp &&
324 (int)tp->rcv_ssthresh < tcp_space(sk) &&
325 !tcp_memory_pressure) {
326 int incr;
327
328 /* Check #2. Increase window, if skb with such overhead
329 * will fit to rcvbuf in future.
330 */
331 if (tcp_win_from_space(skb->truesize) <= skb->len)
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800332 incr = 2 * tp->advmss;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 else
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -0700334 incr = __tcp_grow_window(sk, skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335
336 if (incr) {
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800337 tp->rcv_ssthresh = min(tp->rcv_ssthresh + incr,
338 tp->window_clamp);
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700339 inet_csk(sk)->icsk_ack.quick |= 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 }
341 }
342}
343
344/* 3. Tuning rcvbuf, when connection enters established state. */
345
346static void tcp_fixup_rcvbuf(struct sock *sk)
347{
Eric Dumazete9266a02011-10-20 16:53:56 -0400348 u32 mss = tcp_sk(sk)->advmss;
349 u32 icwnd = TCP_DEFAULT_INIT_RCVWND;
350 int rcvmem;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351
Eric Dumazete9266a02011-10-20 16:53:56 -0400352 /* Limit to 10 segments if mss <= 1460,
353 * or 14600/mss segments, with a minimum of two segments.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 */
Eric Dumazete9266a02011-10-20 16:53:56 -0400355 if (mss > 1460)
356 icwnd = max_t(u32, (1460 * TCP_DEFAULT_INIT_RCVWND) / mss, 2);
357
358 rcvmem = SKB_TRUESIZE(mss + MAX_TCP_HEADER);
359 while (tcp_win_from_space(rcvmem) < mss)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 rcvmem += 128;
Eric Dumazete9266a02011-10-20 16:53:56 -0400361
362 rcvmem *= icwnd;
363
364 if (sk->sk_rcvbuf < rcvmem)
365 sk->sk_rcvbuf = min(rcvmem, sysctl_tcp_rmem[2]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366}
367
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -0800368/* 4. Try to fixup all. It is made immediately after connection enters
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 * established state.
370 */
371static void tcp_init_buffer_space(struct sock *sk)
372{
373 struct tcp_sock *tp = tcp_sk(sk);
374 int maxwin;
375
376 if (!(sk->sk_userlocks & SOCK_RCVBUF_LOCK))
377 tcp_fixup_rcvbuf(sk);
378 if (!(sk->sk_userlocks & SOCK_SNDBUF_LOCK))
379 tcp_fixup_sndbuf(sk);
380
381 tp->rcvq_space.space = tp->rcv_wnd;
382
383 maxwin = tcp_full_space(sk);
384
385 if (tp->window_clamp >= maxwin) {
386 tp->window_clamp = maxwin;
387
388 if (sysctl_tcp_app_win && maxwin > 4 * tp->advmss)
389 tp->window_clamp = max(maxwin -
390 (maxwin >> sysctl_tcp_app_win),
391 4 * tp->advmss);
392 }
393
394 /* Force reservation of one segment. */
395 if (sysctl_tcp_app_win &&
396 tp->window_clamp > 2 * tp->advmss &&
397 tp->window_clamp + tp->advmss > maxwin)
398 tp->window_clamp = max(2 * tp->advmss, maxwin - tp->advmss);
399
400 tp->rcv_ssthresh = min(tp->rcv_ssthresh, tp->window_clamp);
401 tp->snd_cwnd_stamp = tcp_time_stamp;
402}
403
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404/* 5. Recalculate window clamp after socket hit its memory bounds. */
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -0700405static void tcp_clamp_window(struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406{
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -0700407 struct tcp_sock *tp = tcp_sk(sk);
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -0300408 struct inet_connection_sock *icsk = inet_csk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -0300410 icsk->icsk_ack.quick = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411
John Heffner326f36e2005-11-10 17:11:48 -0800412 if (sk->sk_rcvbuf < sysctl_tcp_rmem[2] &&
413 !(sk->sk_userlocks & SOCK_RCVBUF_LOCK) &&
414 !tcp_memory_pressure &&
Eric Dumazet8d987e52010-11-09 23:24:26 +0000415 atomic_long_read(&tcp_memory_allocated) < sysctl_tcp_mem[0]) {
John Heffner326f36e2005-11-10 17:11:48 -0800416 sk->sk_rcvbuf = min(atomic_read(&sk->sk_rmem_alloc),
417 sysctl_tcp_rmem[2]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 }
John Heffner326f36e2005-11-10 17:11:48 -0800419 if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf)
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800420 tp->rcv_ssthresh = min(tp->window_clamp, 2U * tp->advmss);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421}
422
Stephen Hemminger40efc6f2006-01-03 16:03:49 -0800423/* Initialize RCV_MSS value.
424 * RCV_MSS is an our guess about MSS used by the peer.
425 * We haven't any direct information about the MSS.
426 * It's better to underestimate the RCV_MSS rather than overestimate.
427 * Overestimations make us ACKing less frequently than needed.
428 * Underestimations are more easy to detect and fix by tcp_measure_rcv_mss().
429 */
430void tcp_initialize_rcv_mss(struct sock *sk)
431{
Eric Dumazetcf533ea2011-10-21 05:22:42 -0400432 const struct tcp_sock *tp = tcp_sk(sk);
Stephen Hemminger40efc6f2006-01-03 16:03:49 -0800433 unsigned int hint = min_t(unsigned int, tp->advmss, tp->mss_cache);
434
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800435 hint = min(hint, tp->rcv_wnd / 2);
William Allen Simpsonbee7ca92009-11-10 09:51:18 +0000436 hint = min(hint, TCP_MSS_DEFAULT);
Stephen Hemminger40efc6f2006-01-03 16:03:49 -0800437 hint = max(hint, TCP_MIN_MSS);
438
439 inet_csk(sk)->icsk_ack.rcv_mss = hint;
440}
Eric Dumazet4bc2f182010-07-09 21:22:10 +0000441EXPORT_SYMBOL(tcp_initialize_rcv_mss);
Stephen Hemminger40efc6f2006-01-03 16:03:49 -0800442
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443/* Receiver "autotuning" code.
444 *
445 * The algorithm for RTT estimation w/o timestamps is based on
446 * Dynamic Right-Sizing (DRS) by Wu Feng and Mike Fisk of LANL.
Justin P. Mattock631dd1a2010-10-18 11:03:14 +0200447 * <http://public.lanl.gov/radiant/pubs.html#DRS>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 *
449 * More detail on this code can be found at
Justin P. Mattock631dd1a2010-10-18 11:03:14 +0200450 * <http://staff.psc.edu/jheffner/>,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451 * though this reference is out of date. A new paper
452 * is pending.
453 */
454static void tcp_rcv_rtt_update(struct tcp_sock *tp, u32 sample, int win_dep)
455{
456 u32 new_sample = tp->rcv_rtt_est.rtt;
457 long m = sample;
458
459 if (m == 0)
460 m = 1;
461
462 if (new_sample != 0) {
463 /* If we sample in larger samples in the non-timestamp
464 * case, we could grossly overestimate the RTT especially
465 * with chatty applications or bulk transfer apps which
466 * are stalled on filesystem I/O.
467 *
468 * Also, since we are only going for a minimum in the
Stephen Hemminger31f34262005-11-15 15:17:10 -0800469 * non-timestamp case, we do not smooth things out
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -0800470 * else with timestamps disabled convergence takes too
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 * long.
472 */
473 if (!win_dep) {
474 m -= (new_sample >> 3);
475 new_sample += m;
476 } else if (m < new_sample)
477 new_sample = m << 3;
478 } else {
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -0800479 /* No previous measure. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480 new_sample = m << 3;
481 }
482
483 if (tp->rcv_rtt_est.rtt != new_sample)
484 tp->rcv_rtt_est.rtt = new_sample;
485}
486
487static inline void tcp_rcv_rtt_measure(struct tcp_sock *tp)
488{
489 if (tp->rcv_rtt_est.time == 0)
490 goto new_measure;
491 if (before(tp->rcv_nxt, tp->rcv_rtt_est.seq))
492 return;
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800493 tcp_rcv_rtt_update(tp, jiffies - tp->rcv_rtt_est.time, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494
495new_measure:
496 tp->rcv_rtt_est.seq = tp->rcv_nxt + tp->rcv_wnd;
497 tp->rcv_rtt_est.time = tcp_time_stamp;
498}
499
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800500static inline void tcp_rcv_rtt_measure_ts(struct sock *sk,
501 const struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502{
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700503 struct tcp_sock *tp = tcp_sk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 if (tp->rx_opt.rcv_tsecr &&
505 (TCP_SKB_CB(skb)->end_seq -
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700506 TCP_SKB_CB(skb)->seq >= inet_csk(sk)->icsk_ack.rcv_mss))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507 tcp_rcv_rtt_update(tp, tcp_time_stamp - tp->rx_opt.rcv_tsecr, 0);
508}
509
510/*
511 * This function should be called every time data is copied to user space.
512 * It calculates the appropriate TCP receive buffer space.
513 */
514void tcp_rcv_space_adjust(struct sock *sk)
515{
516 struct tcp_sock *tp = tcp_sk(sk);
517 int time;
518 int space;
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900519
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520 if (tp->rcvq_space.time == 0)
521 goto new_measure;
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900522
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523 time = tcp_time_stamp - tp->rcvq_space.time;
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800524 if (time < (tp->rcv_rtt_est.rtt >> 3) || tp->rcv_rtt_est.rtt == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525 return;
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900526
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527 space = 2 * (tp->copied_seq - tp->rcvq_space.seq);
528
529 space = max(tp->rcvq_space.space, space);
530
531 if (tp->rcvq_space.space != space) {
532 int rcvmem;
533
534 tp->rcvq_space.space = space;
535
John Heffner6fcf9412006-02-09 17:06:57 -0800536 if (sysctl_tcp_moderate_rcvbuf &&
537 !(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538 int new_clamp = space;
539
540 /* Receive space grows, normalize in order to
541 * take into account packet headers and sk_buff
542 * structure overhead.
543 */
544 space /= tp->advmss;
545 if (!space)
546 space = 1;
Eric Dumazet87fb4b72011-10-13 07:28:54 +0000547 rcvmem = SKB_TRUESIZE(tp->advmss + MAX_TCP_HEADER);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548 while (tcp_win_from_space(rcvmem) < tp->advmss)
549 rcvmem += 128;
550 space *= rcvmem;
551 space = min(space, sysctl_tcp_rmem[2]);
552 if (space > sk->sk_rcvbuf) {
553 sk->sk_rcvbuf = space;
554
555 /* Make the window clamp follow along. */
556 tp->window_clamp = new_clamp;
557 }
558 }
559 }
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900560
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561new_measure:
562 tp->rcvq_space.seq = tp->copied_seq;
563 tp->rcvq_space.time = tcp_time_stamp;
564}
565
566/* There is something which you must keep in mind when you analyze the
567 * behavior of the tp->ato delayed ack timeout interval. When a
568 * connection starts up, we want to ack as quickly as possible. The
569 * problem is that "good" TCP's do slow start at the beginning of data
570 * transmission. The means that until we send the first few ACK's the
571 * sender will sit on his end and only queue most of his data, because
572 * he can only send snd_cwnd unacked packets at any given time. For
573 * each ACK we send, he increments snd_cwnd and transmits more of his
574 * queue. -DaveM
575 */
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -0700576static void tcp_event_data_recv(struct sock *sk, struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700577{
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -0700578 struct tcp_sock *tp = tcp_sk(sk);
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700579 struct inet_connection_sock *icsk = inet_csk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580 u32 now;
581
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700582 inet_csk_schedule_ack(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700584 tcp_measure_rcv_mss(sk, skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585
586 tcp_rcv_rtt_measure(tp);
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900587
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588 now = tcp_time_stamp;
589
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700590 if (!icsk->icsk_ack.ato) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 /* The _first_ data packet received, initialize
592 * delayed ACK engine.
593 */
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700594 tcp_incr_quickack(sk);
595 icsk->icsk_ack.ato = TCP_ATO_MIN;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596 } else {
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700597 int m = now - icsk->icsk_ack.lrcvtime;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800599 if (m <= TCP_ATO_MIN / 2) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600 /* The fastest case is the first. */
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700601 icsk->icsk_ack.ato = (icsk->icsk_ack.ato >> 1) + TCP_ATO_MIN / 2;
602 } else if (m < icsk->icsk_ack.ato) {
603 icsk->icsk_ack.ato = (icsk->icsk_ack.ato >> 1) + m;
604 if (icsk->icsk_ack.ato > icsk->icsk_rto)
605 icsk->icsk_ack.ato = icsk->icsk_rto;
606 } else if (m > icsk->icsk_rto) {
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -0800607 /* Too long gap. Apparently sender failed to
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608 * restart window, so that we send ACKs quickly.
609 */
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700610 tcp_incr_quickack(sk);
Hideo Aoki3ab224b2007-12-31 00:11:19 -0800611 sk_mem_reclaim(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612 }
613 }
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700614 icsk->icsk_ack.lrcvtime = now;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615
616 TCP_ECN_check_ce(tp, skb);
617
618 if (skb->len >= 128)
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -0700619 tcp_grow_window(sk, skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620}
621
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622/* Called to compute a smoothed rtt estimate. The data fed to this
623 * routine either comes from timestamps, or from segments that were
624 * known _not_ to have been retransmitted [see Karn/Partridge
625 * Proceedings SIGCOMM 87]. The algorithm is from the SIGCOMM 88
626 * piece by Van Jacobson.
627 * NOTE: the next three routines used to be one big routine.
628 * To save cycles in the RFC 1323 implementation it was better to break
629 * it up into three procedures. -- erics
630 */
Stephen Hemminger2d2abba2005-11-10 16:56:12 -0800631static void tcp_rtt_estimator(struct sock *sk, const __u32 mrtt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632{
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -0300633 struct tcp_sock *tp = tcp_sk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634 long m = mrtt; /* RTT */
635
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636 /* The following amusing code comes from Jacobson's
637 * article in SIGCOMM '88. Note that rtt and mdev
638 * are scaled versions of rtt and mean deviation.
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900639 * This is designed to be as fast as possible
Linus Torvalds1da177e2005-04-16 15:20:36 -0700640 * m stands for "measurement".
641 *
642 * On a 1990 paper the rto value is changed to:
643 * RTO = rtt + 4 * mdev
644 *
645 * Funny. This algorithm seems to be very broken.
646 * These formulae increase RTO, when it should be decreased, increase
Stephen Hemminger31f34262005-11-15 15:17:10 -0800647 * too slowly, when it should be increased quickly, decrease too quickly
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648 * etc. I guess in BSD RTO takes ONE value, so that it is absolutely
649 * does not matter how to _calculate_ it. Seems, it was trap
650 * that VJ failed to avoid. 8)
651 */
Stephen Hemminger2de979b2007-03-08 20:45:19 -0800652 if (m == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 m = 1;
654 if (tp->srtt != 0) {
655 m -= (tp->srtt >> 3); /* m is now error in rtt est */
656 tp->srtt += m; /* rtt = 7/8 rtt + 1/8 new */
657 if (m < 0) {
658 m = -m; /* m is now abs(error) */
659 m -= (tp->mdev >> 2); /* similar update on mdev */
660 /* This is similar to one of Eifel findings.
661 * Eifel blocks mdev updates when rtt decreases.
662 * This solution is a bit different: we use finer gain
663 * for mdev in this case (alpha*beta).
664 * Like Eifel it also prevents growth of rto,
665 * but also it limits too fast rto decreases,
666 * happening in pure Eifel.
667 */
668 if (m > 0)
669 m >>= 3;
670 } else {
671 m -= (tp->mdev >> 2); /* similar update on mdev */
672 }
673 tp->mdev += m; /* mdev = 3/4 mdev + 1/4 new */
674 if (tp->mdev > tp->mdev_max) {
675 tp->mdev_max = tp->mdev;
676 if (tp->mdev_max > tp->rttvar)
677 tp->rttvar = tp->mdev_max;
678 }
679 if (after(tp->snd_una, tp->rtt_seq)) {
680 if (tp->mdev_max < tp->rttvar)
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800681 tp->rttvar -= (tp->rttvar - tp->mdev_max) >> 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682 tp->rtt_seq = tp->snd_nxt;
David S. Miller05bb1fa2007-08-30 22:10:28 -0700683 tp->mdev_max = tcp_rto_min(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684 }
685 } else {
686 /* no previous measure. */
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800687 tp->srtt = m << 3; /* take the measured time to be rtt */
688 tp->mdev = m << 1; /* make sure rto = 3*rtt */
David S. Miller05bb1fa2007-08-30 22:10:28 -0700689 tp->mdev_max = tp->rttvar = max(tp->mdev, tcp_rto_min(sk));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700690 tp->rtt_seq = tp->snd_nxt;
691 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692}
693
694/* Calculate rto without backoff. This is the second half of Van Jacobson's
695 * routine referred to above.
696 */
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700697static inline void tcp_set_rto(struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698{
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700699 const struct tcp_sock *tp = tcp_sk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700 /* Old crap is replaced with new one. 8)
701 *
702 * More seriously:
703 * 1. If rtt variance happened to be less 50msec, it is hallucination.
704 * It cannot be less due to utterly erratic ACK generation made
705 * at least by solaris and freebsd. "Erratic ACKs" has _nothing_
706 * to do with delayed acks, because at cwnd>2 true delack timeout
707 * is invisible. Actually, Linux-2.4 also generates erratic
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -0800708 * ACKs in some circumstances.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700709 */
Damian Lukowskif1ecd5d2009-08-26 00:16:31 +0000710 inet_csk(sk)->icsk_rto = __tcp_set_rto(tp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711
712 /* 2. Fixups made earlier cannot be right.
713 * If we do not estimate RTO correctly without them,
714 * all the algo is pure shit and should be replaced
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -0800715 * with correct one. It is exactly, which we pretend to do.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700717
Ilpo Järvinenee6aac52008-12-05 22:43:08 -0800718 /* NOTE: clamping at TCP_RTO_MIN is not required, current algo
719 * guarantees that rto is higher.
720 */
Damian Lukowskif1ecd5d2009-08-26 00:16:31 +0000721 tcp_bound_rto(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722}
723
724/* Save metrics learned by this TCP session.
725 This function is called only, when TCP finishes successfully
726 i.e. when it enters TIME-WAIT or goes from LAST-ACK to CLOSE.
727 */
728void tcp_update_metrics(struct sock *sk)
729{
730 struct tcp_sock *tp = tcp_sk(sk);
731 struct dst_entry *dst = __sk_dst_get(sk);
732
733 if (sysctl_tcp_nometrics_save)
734 return;
735
736 dst_confirm(dst);
737
Ilpo Järvinen056834d2007-12-31 14:57:14 -0800738 if (dst && (dst->flags & DST_HOST)) {
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -0300739 const struct inet_connection_sock *icsk = inet_csk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 int m;
Stephen Hemmingerc1e20f72008-07-18 23:02:15 -0700741 unsigned long rtt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -0300743 if (icsk->icsk_backoff || !tp->srtt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744 /* This session failed to estimate rtt. Why?
745 * Probably, no packets returned in time.
746 * Reset our results.
747 */
748 if (!(dst_metric_locked(dst, RTAX_RTT)))
David S. Millerdefb3512010-12-08 21:16:57 -0800749 dst_metric_set(dst, RTAX_RTT, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700750 return;
751 }
752
Stephen Hemmingerc1e20f72008-07-18 23:02:15 -0700753 rtt = dst_metric_rtt(dst, RTAX_RTT);
754 m = rtt - tp->srtt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755
756 /* If newly calculated rtt larger than stored one,
757 * store new one. Otherwise, use EWMA. Remember,
758 * rtt overestimation is always better than underestimation.
759 */
760 if (!(dst_metric_locked(dst, RTAX_RTT))) {
761 if (m <= 0)
Stephen Hemmingerc1e20f72008-07-18 23:02:15 -0700762 set_dst_metric_rtt(dst, RTAX_RTT, tp->srtt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763 else
Stephen Hemmingerc1e20f72008-07-18 23:02:15 -0700764 set_dst_metric_rtt(dst, RTAX_RTT, rtt - (m >> 3));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 }
766
767 if (!(dst_metric_locked(dst, RTAX_RTTVAR))) {
Stephen Hemmingerc1e20f72008-07-18 23:02:15 -0700768 unsigned long var;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769 if (m < 0)
770 m = -m;
771
772 /* Scale deviation to rttvar fixed point */
773 m >>= 1;
774 if (m < tp->mdev)
775 m = tp->mdev;
776
Stephen Hemmingerc1e20f72008-07-18 23:02:15 -0700777 var = dst_metric_rtt(dst, RTAX_RTTVAR);
778 if (m >= var)
779 var = m;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780 else
Stephen Hemmingerc1e20f72008-07-18 23:02:15 -0700781 var -= (var - m) >> 2;
782
783 set_dst_metric_rtt(dst, RTAX_RTTVAR, var);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 }
785
Ilpo Järvinen0b6a05c2009-09-15 01:30:10 -0700786 if (tcp_in_initial_slowstart(tp)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700787 /* Slow start still did not finish. */
788 if (dst_metric(dst, RTAX_SSTHRESH) &&
789 !dst_metric_locked(dst, RTAX_SSTHRESH) &&
790 (tp->snd_cwnd >> 1) > dst_metric(dst, RTAX_SSTHRESH))
David S. Millerdefb3512010-12-08 21:16:57 -0800791 dst_metric_set(dst, RTAX_SSTHRESH, tp->snd_cwnd >> 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792 if (!dst_metric_locked(dst, RTAX_CWND) &&
793 tp->snd_cwnd > dst_metric(dst, RTAX_CWND))
David S. Millerdefb3512010-12-08 21:16:57 -0800794 dst_metric_set(dst, RTAX_CWND, tp->snd_cwnd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700795 } else if (tp->snd_cwnd > tp->snd_ssthresh &&
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -0300796 icsk->icsk_ca_state == TCP_CA_Open) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797 /* Cong. avoidance phase, cwnd is reliable. */
798 if (!dst_metric_locked(dst, RTAX_SSTHRESH))
David S. Millerdefb3512010-12-08 21:16:57 -0800799 dst_metric_set(dst, RTAX_SSTHRESH,
800 max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801 if (!dst_metric_locked(dst, RTAX_CWND))
David S. Millerdefb3512010-12-08 21:16:57 -0800802 dst_metric_set(dst, RTAX_CWND,
803 (dst_metric(dst, RTAX_CWND) +
804 tp->snd_cwnd) >> 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700805 } else {
806 /* Else slow start did not finish, cwnd is non-sense,
807 ssthresh may be also invalid.
808 */
809 if (!dst_metric_locked(dst, RTAX_CWND))
David S. Millerdefb3512010-12-08 21:16:57 -0800810 dst_metric_set(dst, RTAX_CWND,
811 (dst_metric(dst, RTAX_CWND) +
812 tp->snd_ssthresh) >> 1);
Satoru SATOH5ffc02a2008-05-04 22:14:42 -0700813 if (dst_metric(dst, RTAX_SSTHRESH) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700814 !dst_metric_locked(dst, RTAX_SSTHRESH) &&
Satoru SATOH5ffc02a2008-05-04 22:14:42 -0700815 tp->snd_ssthresh > dst_metric(dst, RTAX_SSTHRESH))
David S. Millerdefb3512010-12-08 21:16:57 -0800816 dst_metric_set(dst, RTAX_SSTHRESH, tp->snd_ssthresh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700817 }
818
819 if (!dst_metric_locked(dst, RTAX_REORDERING)) {
Satoru SATOH5ffc02a2008-05-04 22:14:42 -0700820 if (dst_metric(dst, RTAX_REORDERING) < tp->reordering &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821 tp->reordering != sysctl_tcp_reordering)
David S. Millerdefb3512010-12-08 21:16:57 -0800822 dst_metric_set(dst, RTAX_REORDERING, tp->reordering);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700823 }
824 }
825}
826
Eric Dumazetcf533ea2011-10-21 05:22:42 -0400827__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828{
829 __u32 cwnd = (dst ? dst_metric(dst, RTAX_INITCWND) : 0);
830
Gerrit Renker22b71c82010-08-29 19:23:12 +0000831 if (!cwnd)
David S. Miller442b9632011-02-02 17:05:11 -0800832 cwnd = TCP_INIT_CWND;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700833 return min_t(__u32, cwnd, tp->snd_cwnd_clamp);
834}
835
Stephen Hemminger40efc6f2006-01-03 16:03:49 -0800836/* Set slow start threshold and cwnd not falling to slow start */
Ilpo Järvinen3cfe3ba2007-02-27 10:09:49 -0800837void tcp_enter_cwr(struct sock *sk, const int set_ssthresh)
Stephen Hemminger40efc6f2006-01-03 16:03:49 -0800838{
839 struct tcp_sock *tp = tcp_sk(sk);
Ilpo Järvinen3cfe3ba2007-02-27 10:09:49 -0800840 const struct inet_connection_sock *icsk = inet_csk(sk);
Stephen Hemminger40efc6f2006-01-03 16:03:49 -0800841
842 tp->prior_ssthresh = 0;
843 tp->bytes_acked = 0;
Ilpo Järvinene01f9d72007-03-02 13:27:25 -0800844 if (icsk->icsk_ca_state < TCP_CA_CWR) {
Stephen Hemminger40efc6f2006-01-03 16:03:49 -0800845 tp->undo_marker = 0;
Ilpo Järvinen3cfe3ba2007-02-27 10:09:49 -0800846 if (set_ssthresh)
847 tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk);
Stephen Hemminger40efc6f2006-01-03 16:03:49 -0800848 tp->snd_cwnd = min(tp->snd_cwnd,
849 tcp_packets_in_flight(tp) + 1U);
850 tp->snd_cwnd_cnt = 0;
851 tp->high_seq = tp->snd_nxt;
852 tp->snd_cwnd_stamp = tcp_time_stamp;
853 TCP_ECN_queue_cwr(tp);
854
855 tcp_set_ca_state(sk, TCP_CA_CWR);
856 }
857}
858
Ilpo Järvinene60402d2007-08-09 15:14:46 +0300859/*
860 * Packet counting of FACK is based on in-order assumptions, therefore TCP
861 * disables it when reordering is detected
862 */
863static void tcp_disable_fack(struct tcp_sock *tp)
864{
Ilpo Järvinen85cc3912007-11-15 19:39:31 -0800865 /* RFC3517 uses different metric in lost marker => reset on change */
866 if (tcp_is_fack(tp))
867 tp->lost_skb_hint = NULL;
Ilpo Järvinene60402d2007-08-09 15:14:46 +0300868 tp->rx_opt.sack_ok &= ~2;
869}
870
Ryousei Takano564262c12007-10-25 23:03:52 -0700871/* Take a notice that peer is sending D-SACKs */
Ilpo Järvinene60402d2007-08-09 15:14:46 +0300872static void tcp_dsack_seen(struct tcp_sock *tp)
873{
874 tp->rx_opt.sack_ok |= 4;
875}
876
Linus Torvalds1da177e2005-04-16 15:20:36 -0700877/* Initialize metrics on socket. */
878
879static void tcp_init_metrics(struct sock *sk)
880{
881 struct tcp_sock *tp = tcp_sk(sk);
882 struct dst_entry *dst = __sk_dst_get(sk);
883
884 if (dst == NULL)
885 goto reset;
886
887 dst_confirm(dst);
888
889 if (dst_metric_locked(dst, RTAX_CWND))
890 tp->snd_cwnd_clamp = dst_metric(dst, RTAX_CWND);
891 if (dst_metric(dst, RTAX_SSTHRESH)) {
892 tp->snd_ssthresh = dst_metric(dst, RTAX_SSTHRESH);
893 if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
894 tp->snd_ssthresh = tp->snd_cwnd_clamp;
Jerry Chu9ad7c042011-06-08 11:08:38 +0000895 } else {
896 /* ssthresh may have been reduced unnecessarily during.
897 * 3WHS. Restore it back to its initial default.
898 */
899 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900 }
901 if (dst_metric(dst, RTAX_REORDERING) &&
902 tp->reordering != dst_metric(dst, RTAX_REORDERING)) {
Ilpo Järvinene60402d2007-08-09 15:14:46 +0300903 tcp_disable_fack(tp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904 tp->reordering = dst_metric(dst, RTAX_REORDERING);
905 }
906
Jerry Chu9ad7c042011-06-08 11:08:38 +0000907 if (dst_metric(dst, RTAX_RTT) == 0 || tp->srtt == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908 goto reset;
909
910 /* Initial rtt is determined from SYN,SYN-ACK.
911 * The segment is small and rtt may appear much
912 * less than real one. Use per-dst memory
913 * to make it more realistic.
914 *
915 * A bit of theory. RTT is time passed after "normal" sized packet
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -0800916 * is sent until it is ACKed. In normal circumstances sending small
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917 * packets force peer to delay ACKs and calculation is correct too.
918 * The algorithm is adaptive and, provided we follow specs, it
919 * NEVER underestimate RTT. BUT! If peer tries to make some clever
920 * tricks sort of "quick acks" for time long enough to decrease RTT
921 * to low value, and then abruptly stops to do it and starts to delay
922 * ACKs, wait for troubles.
923 */
Stephen Hemmingerc1e20f72008-07-18 23:02:15 -0700924 if (dst_metric_rtt(dst, RTAX_RTT) > tp->srtt) {
925 tp->srtt = dst_metric_rtt(dst, RTAX_RTT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700926 tp->rtt_seq = tp->snd_nxt;
927 }
Stephen Hemmingerc1e20f72008-07-18 23:02:15 -0700928 if (dst_metric_rtt(dst, RTAX_RTTVAR) > tp->mdev) {
929 tp->mdev = dst_metric_rtt(dst, RTAX_RTTVAR);
Satoru SATOH488faa22007-12-16 14:00:19 -0800930 tp->mdev_max = tp->rttvar = max(tp->mdev, tcp_rto_min(sk));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931 }
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700932 tcp_set_rto(sk);
Jiri Kosinad9f4fba2010-12-22 23:23:38 +0000933reset:
Jerry Chu9ad7c042011-06-08 11:08:38 +0000934 if (tp->srtt == 0) {
935 /* RFC2988bis: We've failed to get a valid RTT sample from
936 * 3WHS. This is most likely due to retransmission,
937 * including spurious one. Reset the RTO back to 3secs
938 * from the more aggressive 1sec to avoid more spurious
939 * retransmission.
Jiri Kosinad9f4fba2010-12-22 23:23:38 +0000940 */
Jerry Chu9ad7c042011-06-08 11:08:38 +0000941 tp->mdev = tp->mdev_max = tp->rttvar = TCP_TIMEOUT_FALLBACK;
942 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
Jiri Kosinad9f4fba2010-12-22 23:23:38 +0000943 }
Jerry Chu9ad7c042011-06-08 11:08:38 +0000944 /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
945 * retransmitted. In light of RFC2988bis' more aggressive 1sec
946 * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
947 * retransmission has occurred.
948 */
949 if (tp->total_retrans > 1)
950 tp->snd_cwnd = 1;
951 else
952 tp->snd_cwnd = tcp_init_cwnd(tp, dst);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700953 tp->snd_cwnd_stamp = tcp_time_stamp;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954}
955
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -0300956static void tcp_update_reordering(struct sock *sk, const int metric,
957 const int ts)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700958{
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -0300959 struct tcp_sock *tp = tcp_sk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700960 if (metric > tp->reordering) {
Pavel Emelyanov40b215e2008-07-03 01:05:41 -0700961 int mib_idx;
962
Linus Torvalds1da177e2005-04-16 15:20:36 -0700963 tp->reordering = min(TCP_MAX_REORDERING, metric);
964
965 /* This exciting event is worth to be remembered. 8) */
966 if (ts)
Pavel Emelyanov40b215e2008-07-03 01:05:41 -0700967 mib_idx = LINUX_MIB_TCPTSREORDER;
Ilpo Järvinene60402d2007-08-09 15:14:46 +0300968 else if (tcp_is_reno(tp))
Pavel Emelyanov40b215e2008-07-03 01:05:41 -0700969 mib_idx = LINUX_MIB_TCPRENOREORDER;
Ilpo Järvinene60402d2007-08-09 15:14:46 +0300970 else if (tcp_is_fack(tp))
Pavel Emelyanov40b215e2008-07-03 01:05:41 -0700971 mib_idx = LINUX_MIB_TCPFACKREORDER;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972 else
Pavel Emelyanov40b215e2008-07-03 01:05:41 -0700973 mib_idx = LINUX_MIB_TCPSACKREORDER;
974
Pavel Emelyanovde0744a2008-07-16 20:31:16 -0700975 NET_INC_STATS_BH(sock_net(sk), mib_idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700976#if FASTRETRANS_DEBUG > 1
977 printk(KERN_DEBUG "Disorder%d %d %u f%u s%u rr%d\n",
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -0300978 tp->rx_opt.sack_ok, inet_csk(sk)->icsk_ca_state,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700979 tp->reordering,
980 tp->fackets_out,
981 tp->sacked_out,
982 tp->undo_marker ? tp->undo_retrans : 0);
983#endif
Ilpo Järvinene60402d2007-08-09 15:14:46 +0300984 tcp_disable_fack(tp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985 }
986}
987
Ilpo Järvinen006f5822008-09-20 21:20:20 -0700988/* This must be called before lost_out is incremented */
Ilpo Järvinenc8c213f2008-09-20 21:18:55 -0700989static void tcp_verify_retransmit_hint(struct tcp_sock *tp, struct sk_buff *skb)
990{
Ilpo Järvinen006f5822008-09-20 21:20:20 -0700991 if ((tp->retransmit_skb_hint == NULL) ||
Ilpo Järvinenc8c213f2008-09-20 21:18:55 -0700992 before(TCP_SKB_CB(skb)->seq,
993 TCP_SKB_CB(tp->retransmit_skb_hint)->seq))
Ilpo Järvinen006f5822008-09-20 21:20:20 -0700994 tp->retransmit_skb_hint = skb;
995
996 if (!tp->lost_out ||
997 after(TCP_SKB_CB(skb)->end_seq, tp->retransmit_high))
998 tp->retransmit_high = TCP_SKB_CB(skb)->end_seq;
Ilpo Järvinenc8c213f2008-09-20 21:18:55 -0700999}
1000
Ilpo Järvinen41ea36e2008-09-20 21:19:22 -07001001static void tcp_skb_mark_lost(struct tcp_sock *tp, struct sk_buff *skb)
1002{
1003 if (!(TCP_SKB_CB(skb)->sacked & (TCPCB_LOST|TCPCB_SACKED_ACKED))) {
1004 tcp_verify_retransmit_hint(tp, skb);
1005
1006 tp->lost_out += tcp_skb_pcount(skb);
1007 TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
1008 }
1009}
1010
Ilpo Järvinene1aa6802008-11-24 21:11:55 -08001011static void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp,
1012 struct sk_buff *skb)
Ilpo Järvinen006f5822008-09-20 21:20:20 -07001013{
1014 tcp_verify_retransmit_hint(tp, skb);
1015
1016 if (!(TCP_SKB_CB(skb)->sacked & (TCPCB_LOST|TCPCB_SACKED_ACKED))) {
1017 tp->lost_out += tcp_skb_pcount(skb);
1018 TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
1019 }
1020}
1021
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022/* This procedure tags the retransmission queue when SACKs arrive.
1023 *
1024 * We have three tag bits: SACKED(S), RETRANS(R) and LOST(L).
1025 * Packets in queue with these bits set are counted in variables
1026 * sacked_out, retrans_out and lost_out, correspondingly.
1027 *
1028 * Valid combinations are:
1029 * Tag InFlight Description
1030 * 0 1 - orig segment is in flight.
1031 * S 0 - nothing flies, orig reached receiver.
1032 * L 0 - nothing flies, orig lost by net.
1033 * R 2 - both orig and retransmit are in flight.
1034 * L|R 1 - orig is lost, retransmit is in flight.
1035 * S|R 1 - orig reached receiver, retrans is still in flight.
1036 * (L|S|R is logically valid, it could occur when L|R is sacked,
1037 * but it is equivalent to plain S and code short-curcuits it to S.
1038 * L|S is logically invalid, it would mean -1 packet in flight 8))
1039 *
1040 * These 6 states form finite state machine, controlled by the following events:
1041 * 1. New ACK (+SACK) arrives. (tcp_sacktag_write_queue())
1042 * 2. Retransmission. (tcp_retransmit_skb(), tcp_xmit_retransmit_queue())
1043 * 3. Loss detection event of one of three flavors:
1044 * A. Scoreboard estimator decided the packet is lost.
1045 * A'. Reno "three dupacks" marks head of queue lost.
1046 * A''. Its FACK modfication, head until snd.fack is lost.
1047 * B. SACK arrives sacking data transmitted after never retransmitted
1048 * hole was sent out.
1049 * C. SACK arrives sacking SND.NXT at the moment, when the
1050 * segment was retransmitted.
1051 * 4. D-SACK added new rule: D-SACK changes any tag to S.
1052 *
1053 * It is pleasant to note, that state diagram turns out to be commutative,
1054 * so that we are allowed not to be bothered by order of our actions,
1055 * when multiple events arrive simultaneously. (see the function below).
1056 *
1057 * Reordering detection.
1058 * --------------------
1059 * Reordering metric is maximal distance, which a packet can be displaced
1060 * in packet stream. With SACKs we can estimate it:
1061 *
1062 * 1. SACK fills old hole and the corresponding segment was not
1063 * ever retransmitted -> reordering. Alas, we cannot use it
1064 * when segment was retransmitted.
1065 * 2. The last flaw is solved with D-SACK. D-SACK arrives
1066 * for retransmitted and already SACKed segment -> reordering..
1067 * Both of these heuristics are not used in Loss state, when we cannot
1068 * account for retransmits accurately.
Ilpo Järvinen5b3c9882007-08-24 22:54:44 -07001069 *
1070 * SACK block validation.
1071 * ----------------------
1072 *
1073 * SACK block range validation checks that the received SACK block fits to
1074 * the expected sequence limits, i.e., it is between SND.UNA and SND.NXT.
1075 * Note that SND.UNA is not included to the range though being valid because
Ilpo Järvinen0e835332007-10-01 15:28:17 -07001076 * it means that the receiver is rather inconsistent with itself reporting
1077 * SACK reneging when it should advance SND.UNA. Such SACK block this is
1078 * perfectly valid, however, in light of RFC2018 which explicitly states
1079 * that "SACK block MUST reflect the newest segment. Even if the newest
1080 * segment is going to be discarded ...", not that it looks very clever
1081 * in case of head skb. Due to potentional receiver driven attacks, we
1082 * choose to avoid immediate execution of a walk in write queue due to
1083 * reneging and defer head skb's loss recovery to standard loss recovery
1084 * procedure that will eventually trigger (nothing forbids us doing this).
Ilpo Järvinen5b3c9882007-08-24 22:54:44 -07001085 *
1086 * Implements also blockage to start_seq wrap-around. Problem lies in the
1087 * fact that though start_seq (s) is before end_seq (i.e., not reversed),
1088 * there's no guarantee that it will be before snd_nxt (n). The problem
1089 * happens when start_seq resides between end_seq wrap (e_w) and snd_nxt
1090 * wrap (s_w):
1091 *
1092 * <- outs wnd -> <- wrapzone ->
1093 * u e n u_w e_w s n_w
1094 * | | | | | | |
1095 * |<------------+------+----- TCP seqno space --------------+---------->|
1096 * ...-- <2^31 ->| |<--------...
1097 * ...---- >2^31 ------>| |<--------...
1098 *
1099 * Current code wouldn't be vulnerable but it's better still to discard such
1100 * crazy SACK blocks. Doing this check for start_seq alone closes somewhat
1101 * similar case (end_seq after snd_nxt wrap) as earlier reversed check in
1102 * snd_nxt wrap -> snd_una region will then become "well defined", i.e.,
1103 * equal to the ideal case (infinite seqno space without wrap caused issues).
1104 *
1105 * With D-SACK the lower bound is extended to cover sequence space below
1106 * SND.UNA down to undo_marker, which is the last point of interest. Yet
Ryousei Takano564262c12007-10-25 23:03:52 -07001107 * again, D-SACK block must not to go across snd_una (for the same reason as
Ilpo Järvinen5b3c9882007-08-24 22:54:44 -07001108 * for the normal SACK blocks, explained above). But there all simplicity
1109 * ends, TCP might receive valid D-SACKs below that. As long as they reside
1110 * fully below undo_marker they do not affect behavior in anyway and can
1111 * therefore be safely ignored. In rare cases (which are more or less
1112 * theoretical ones), the D-SACK will nicely cross that boundary due to skb
1113 * fragmentation and packet reordering past skb's retransmission. To consider
1114 * them correctly, the acceptable range must be extended even more though
1115 * the exact amount is rather hard to quantify. However, tp->max_window can
1116 * be used as an exaggerated estimate.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001117 */
Ilpo Järvinen5b3c9882007-08-24 22:54:44 -07001118static int tcp_is_sackblock_valid(struct tcp_sock *tp, int is_dsack,
1119 u32 start_seq, u32 end_seq)
1120{
1121 /* Too far in future, or reversed (interpretation is ambiguous) */
1122 if (after(end_seq, tp->snd_nxt) || !before(start_seq, end_seq))
1123 return 0;
1124
1125 /* Nasty start_seq wrap-around check (see comments above) */
1126 if (!before(start_seq, tp->snd_nxt))
1127 return 0;
1128
Ryousei Takano564262c12007-10-25 23:03:52 -07001129 /* In outstanding window? ...This is valid exit for D-SACKs too.
Ilpo Järvinen5b3c9882007-08-24 22:54:44 -07001130 * start_seq == snd_una is non-sensical (see comments above)
1131 */
1132 if (after(start_seq, tp->snd_una))
1133 return 1;
1134
1135 if (!is_dsack || !tp->undo_marker)
1136 return 0;
1137
1138 /* ...Then it's D-SACK, and must reside below snd_una completely */
Zheng Yanf779b2d2011-09-18 22:37:34 -04001139 if (after(end_seq, tp->snd_una))
Ilpo Järvinen5b3c9882007-08-24 22:54:44 -07001140 return 0;
1141
1142 if (!before(start_seq, tp->undo_marker))
1143 return 1;
1144
1145 /* Too old */
1146 if (!after(end_seq, tp->undo_marker))
1147 return 0;
1148
1149 /* Undo_marker boundary crossing (overestimates a lot). Known already:
1150 * start_seq < undo_marker and end_seq >= undo_marker.
1151 */
1152 return !before(start_seq, end_seq - tp->max_window);
1153}
1154
Ilpo Järvinen1c1e87e2007-10-10 02:45:32 -07001155/* Check for lost retransmit. This superb idea is borrowed from "ratehalving".
1156 * Event "C". Later note: FACK people cheated me again 8), we have to account
1157 * for reordering! Ugly, but should help.
Ilpo Järvinenf785a8e2007-10-11 17:35:41 -07001158 *
1159 * Search retransmitted skbs from write_queue that were sent when snd_nxt was
1160 * less than what is now known to be received by the other end (derived from
Ilpo Järvinen9f58f3b2007-11-15 19:42:54 -08001161 * highest SACK block). Also calculate the lowest snd_nxt among the remaining
1162 * retransmitted skbs to avoid some costly processing per ACKs.
Ilpo Järvinen1c1e87e2007-10-10 02:45:32 -07001163 */
Ilpo Järvinen407ef1d2007-12-02 00:47:57 +02001164static void tcp_mark_lost_retrans(struct sock *sk)
Ilpo Järvinen1c1e87e2007-10-10 02:45:32 -07001165{
Ilpo Järvinen9f58f3b2007-11-15 19:42:54 -08001166 const struct inet_connection_sock *icsk = inet_csk(sk);
Ilpo Järvinen1c1e87e2007-10-10 02:45:32 -07001167 struct tcp_sock *tp = tcp_sk(sk);
1168 struct sk_buff *skb;
Ilpo Järvinenf785a8e2007-10-11 17:35:41 -07001169 int cnt = 0;
Ilpo Järvinendf2e0142007-10-18 05:07:57 -07001170 u32 new_low_seq = tp->snd_nxt;
Ilpo Järvinen6859d492007-12-02 00:48:06 +02001171 u32 received_upto = tcp_highest_sack_seq(tp);
Ilpo Järvinen9f58f3b2007-11-15 19:42:54 -08001172
1173 if (!tcp_is_fack(tp) || !tp->retrans_out ||
1174 !after(received_upto, tp->lost_retrans_low) ||
1175 icsk->icsk_ca_state != TCP_CA_Recovery)
Ilpo Järvinen407ef1d2007-12-02 00:47:57 +02001176 return;
Ilpo Järvinen1c1e87e2007-10-10 02:45:32 -07001177
1178 tcp_for_write_queue(skb, sk) {
1179 u32 ack_seq = TCP_SKB_CB(skb)->ack_seq;
1180
1181 if (skb == tcp_send_head(sk))
1182 break;
Ilpo Järvinenf785a8e2007-10-11 17:35:41 -07001183 if (cnt == tp->retrans_out)
Ilpo Järvinen1c1e87e2007-10-10 02:45:32 -07001184 break;
1185 if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una))
1186 continue;
1187
Ilpo Järvinenf785a8e2007-10-11 17:35:41 -07001188 if (!(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS))
1189 continue;
1190
Ilpo Järvinend0af4162009-02-28 04:44:32 +00001191 /* TODO: We would like to get rid of tcp_is_fack(tp) only
1192 * constraint here (see above) but figuring out that at
1193 * least tp->reordering SACK blocks reside between ack_seq
1194 * and received_upto is not easy task to do cheaply with
1195 * the available datastructures.
1196 *
1197 * Whether FACK should check here for tp->reordering segs
1198 * in-between one could argue for either way (it would be
1199 * rather simple to implement as we could count fack_count
1200 * during the walk and do tp->fackets_out - fack_count).
1201 */
1202 if (after(received_upto, ack_seq)) {
Ilpo Järvinen1c1e87e2007-10-10 02:45:32 -07001203 TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
1204 tp->retrans_out -= tcp_skb_pcount(skb);
1205
Ilpo Järvinen006f5822008-09-20 21:20:20 -07001206 tcp_skb_mark_lost_uncond_verify(tp, skb);
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07001207 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSTRETRANSMIT);
Ilpo Järvinenf785a8e2007-10-11 17:35:41 -07001208 } else {
Ilpo Järvinendf2e0142007-10-18 05:07:57 -07001209 if (before(ack_seq, new_low_seq))
Ilpo Järvinenb08d6cb2007-10-11 17:36:13 -07001210 new_low_seq = ack_seq;
Ilpo Järvinenf785a8e2007-10-11 17:35:41 -07001211 cnt += tcp_skb_pcount(skb);
Ilpo Järvinen1c1e87e2007-10-10 02:45:32 -07001212 }
1213 }
Ilpo Järvinenb08d6cb2007-10-11 17:36:13 -07001214
1215 if (tp->retrans_out)
1216 tp->lost_retrans_low = new_low_seq;
Ilpo Järvinen1c1e87e2007-10-10 02:45:32 -07001217}
Ilpo Järvinen5b3c9882007-08-24 22:54:44 -07001218
Eric Dumazetcf533ea2011-10-21 05:22:42 -04001219static int tcp_check_dsack(struct sock *sk, const struct sk_buff *ack_skb,
David S. Millerd06e0212007-06-18 22:43:06 -07001220 struct tcp_sack_block_wire *sp, int num_sacks,
1221 u32 prior_snd_una)
1222{
Pavel Emelyanov1ed83462008-07-16 20:29:51 -07001223 struct tcp_sock *tp = tcp_sk(sk);
Harvey Harrisond3e2ce32008-05-02 16:26:16 -07001224 u32 start_seq_0 = get_unaligned_be32(&sp[0].start_seq);
1225 u32 end_seq_0 = get_unaligned_be32(&sp[0].end_seq);
David S. Millerd06e0212007-06-18 22:43:06 -07001226 int dup_sack = 0;
1227
1228 if (before(start_seq_0, TCP_SKB_CB(ack_skb)->ack_seq)) {
1229 dup_sack = 1;
Ilpo Järvinene60402d2007-08-09 15:14:46 +03001230 tcp_dsack_seen(tp);
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07001231 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPDSACKRECV);
David S. Millerd06e0212007-06-18 22:43:06 -07001232 } else if (num_sacks > 1) {
Harvey Harrisond3e2ce32008-05-02 16:26:16 -07001233 u32 end_seq_1 = get_unaligned_be32(&sp[1].end_seq);
1234 u32 start_seq_1 = get_unaligned_be32(&sp[1].start_seq);
David S. Millerd06e0212007-06-18 22:43:06 -07001235
1236 if (!after(end_seq_0, end_seq_1) &&
1237 !before(start_seq_0, start_seq_1)) {
1238 dup_sack = 1;
Ilpo Järvinene60402d2007-08-09 15:14:46 +03001239 tcp_dsack_seen(tp);
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07001240 NET_INC_STATS_BH(sock_net(sk),
1241 LINUX_MIB_TCPDSACKOFORECV);
David S. Millerd06e0212007-06-18 22:43:06 -07001242 }
1243 }
1244
1245 /* D-SACK for already forgotten data... Do dumb counting. */
Yuchung Chengc24f6912011-02-07 12:57:04 +00001246 if (dup_sack && tp->undo_marker && tp->undo_retrans &&
David S. Millerd06e0212007-06-18 22:43:06 -07001247 !after(end_seq_0, prior_snd_una) &&
1248 after(end_seq_0, tp->undo_marker))
1249 tp->undo_retrans--;
1250
1251 return dup_sack;
1252}
1253
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001254struct tcp_sacktag_state {
1255 int reord;
1256 int fack_count;
1257 int flag;
1258};
1259
Ilpo Järvinend1935942007-10-11 17:34:25 -07001260/* Check if skb is fully within the SACK block. In presence of GSO skbs,
1261 * the incoming SACK may not exactly match but we can find smaller MSS
1262 * aligned portion of it that matches. Therefore we might need to fragment
1263 * which may fail and creates some hassle (caller must handle error case
1264 * returns).
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001265 *
1266 * FIXME: this could be merged to shift decision code
Ilpo Järvinend1935942007-10-11 17:34:25 -07001267 */
Adrian Bunk0f79efd2007-10-26 03:57:36 -07001268static int tcp_match_skb_to_sack(struct sock *sk, struct sk_buff *skb,
1269 u32 start_seq, u32 end_seq)
Ilpo Järvinend1935942007-10-11 17:34:25 -07001270{
1271 int in_sack, err;
1272 unsigned int pkt_len;
Ilpo Järvinenadb92db2008-11-24 21:13:50 -08001273 unsigned int mss;
Ilpo Järvinend1935942007-10-11 17:34:25 -07001274
1275 in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq) &&
1276 !before(end_seq, TCP_SKB_CB(skb)->end_seq);
1277
1278 if (tcp_skb_pcount(skb) > 1 && !in_sack &&
1279 after(TCP_SKB_CB(skb)->end_seq, start_seq)) {
Ilpo Järvinenadb92db2008-11-24 21:13:50 -08001280 mss = tcp_skb_mss(skb);
Ilpo Järvinend1935942007-10-11 17:34:25 -07001281 in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq);
1282
Ilpo Järvinenadb92db2008-11-24 21:13:50 -08001283 if (!in_sack) {
Ilpo Järvinend1935942007-10-11 17:34:25 -07001284 pkt_len = start_seq - TCP_SKB_CB(skb)->seq;
Ilpo Järvinenadb92db2008-11-24 21:13:50 -08001285 if (pkt_len < mss)
1286 pkt_len = mss;
1287 } else {
Ilpo Järvinend1935942007-10-11 17:34:25 -07001288 pkt_len = end_seq - TCP_SKB_CB(skb)->seq;
Ilpo Järvinenadb92db2008-11-24 21:13:50 -08001289 if (pkt_len < mss)
1290 return -EINVAL;
1291 }
1292
1293 /* Round if necessary so that SACKs cover only full MSSes
1294 * and/or the remaining small portion (if present)
1295 */
1296 if (pkt_len > mss) {
1297 unsigned int new_len = (pkt_len / mss) * mss;
1298 if (!in_sack && new_len < pkt_len) {
1299 new_len += mss;
1300 if (new_len > skb->len)
1301 return 0;
1302 }
1303 pkt_len = new_len;
1304 }
1305 err = tcp_fragment(sk, skb, pkt_len, mss);
Ilpo Järvinend1935942007-10-11 17:34:25 -07001306 if (err < 0)
1307 return err;
1308 }
1309
1310 return in_sack;
1311}
1312
Eric Dumazetcf533ea2011-10-21 05:22:42 -04001313static u8 tcp_sacktag_one(const struct sk_buff *skb, struct sock *sk,
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001314 struct tcp_sacktag_state *state,
1315 int dup_sack, int pcount)
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001316{
Ilpo Järvinen6859d492007-12-02 00:48:06 +02001317 struct tcp_sock *tp = tcp_sk(sk);
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001318 u8 sacked = TCP_SKB_CB(skb)->sacked;
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001319 int fack_count = state->fack_count;
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001320
1321 /* Account D-SACK for retransmitted packet. */
1322 if (dup_sack && (sacked & TCPCB_RETRANS)) {
Yuchung Chengc24f6912011-02-07 12:57:04 +00001323 if (tp->undo_marker && tp->undo_retrans &&
1324 after(TCP_SKB_CB(skb)->end_seq, tp->undo_marker))
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001325 tp->undo_retrans--;
Ilpo Järvinenede9f3b2007-12-02 00:47:58 +02001326 if (sacked & TCPCB_SACKED_ACKED)
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001327 state->reord = min(fack_count, state->reord);
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001328 }
1329
1330 /* Nothing to do; acked frame is about to be dropped (was ACKed). */
1331 if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una))
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001332 return sacked;
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001333
1334 if (!(sacked & TCPCB_SACKED_ACKED)) {
1335 if (sacked & TCPCB_SACKED_RETRANS) {
1336 /* If the segment is not tagged as lost,
1337 * we do not clear RETRANS, believing
1338 * that retransmission is still in flight.
1339 */
1340 if (sacked & TCPCB_LOST) {
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001341 sacked &= ~(TCPCB_LOST|TCPCB_SACKED_RETRANS);
Ilpo Järvinenf58b22f2008-11-24 21:14:43 -08001342 tp->lost_out -= pcount;
1343 tp->retrans_out -= pcount;
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001344 }
1345 } else {
1346 if (!(sacked & TCPCB_RETRANS)) {
1347 /* New sack for not retransmitted frame,
1348 * which was in hole. It is reordering.
1349 */
1350 if (before(TCP_SKB_CB(skb)->seq,
1351 tcp_highest_sack_seq(tp)))
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001352 state->reord = min(fack_count,
1353 state->reord);
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001354
1355 /* SACK enhanced F-RTO (RFC4138; Appendix B) */
1356 if (!after(TCP_SKB_CB(skb)->end_seq, tp->frto_highmark))
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001357 state->flag |= FLAG_ONLY_ORIG_SACKED;
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001358 }
1359
1360 if (sacked & TCPCB_LOST) {
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001361 sacked &= ~TCPCB_LOST;
Ilpo Järvinenf58b22f2008-11-24 21:14:43 -08001362 tp->lost_out -= pcount;
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001363 }
1364 }
1365
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001366 sacked |= TCPCB_SACKED_ACKED;
1367 state->flag |= FLAG_DATA_SACKED;
Ilpo Järvinenf58b22f2008-11-24 21:14:43 -08001368 tp->sacked_out += pcount;
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001369
Ilpo Järvinenf58b22f2008-11-24 21:14:43 -08001370 fack_count += pcount;
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001371
1372 /* Lost marker hint past SACKed? Tweak RFC3517 cnt */
1373 if (!tcp_is_fack(tp) && (tp->lost_skb_hint != NULL) &&
1374 before(TCP_SKB_CB(skb)->seq,
1375 TCP_SKB_CB(tp->lost_skb_hint)->seq))
Ilpo Järvinenf58b22f2008-11-24 21:14:43 -08001376 tp->lost_cnt_hint += pcount;
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001377
1378 if (fack_count > tp->fackets_out)
1379 tp->fackets_out = fack_count;
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001380 }
1381
1382 /* D-SACK. We can detect redundant retransmission in S|R and plain R
1383 * frames and clear it. undo_retrans is decreased above, L|R frames
1384 * are accounted above as well.
1385 */
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001386 if (dup_sack && (sacked & TCPCB_SACKED_RETRANS)) {
1387 sacked &= ~TCPCB_SACKED_RETRANS;
Ilpo Järvinenf58b22f2008-11-24 21:14:43 -08001388 tp->retrans_out -= pcount;
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001389 }
1390
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001391 return sacked;
Ilpo Järvinen9e10c47c2007-11-15 19:44:56 -08001392}
1393
Ilpo Järvinen50133162008-12-05 22:42:41 -08001394static int tcp_shifted_skb(struct sock *sk, struct sk_buff *skb,
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001395 struct tcp_sacktag_state *state,
Ilpo Järvinen9ec06ff2009-03-01 00:21:36 -08001396 unsigned int pcount, int shifted, int mss,
1397 int dup_sack)
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001398{
1399 struct tcp_sock *tp = tcp_sk(sk);
Ilpo Järvinen50133162008-12-05 22:42:41 -08001400 struct sk_buff *prev = tcp_write_queue_prev(sk, skb);
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001401
1402 BUG_ON(!pcount);
1403
Yan, Zheng1e5289e2011-10-02 04:21:50 +00001404 if (skb == tp->lost_skb_hint)
Ilpo Järvinen92ee76b2008-11-24 21:26:56 -08001405 tp->lost_cnt_hint += pcount;
1406
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001407 TCP_SKB_CB(prev)->end_seq += shifted;
1408 TCP_SKB_CB(skb)->seq += shifted;
1409
1410 skb_shinfo(prev)->gso_segs += pcount;
1411 BUG_ON(skb_shinfo(skb)->gso_segs < pcount);
1412 skb_shinfo(skb)->gso_segs -= pcount;
1413
1414 /* When we're adding to gso_segs == 1, gso_size will be zero,
1415 * in theory this shouldn't be necessary but as long as DSACK
1416 * code can come after this skb later on it's better to keep
1417 * setting gso_size to something.
1418 */
1419 if (!skb_shinfo(prev)->gso_size) {
1420 skb_shinfo(prev)->gso_size = mss;
1421 skb_shinfo(prev)->gso_type = sk->sk_gso_type;
1422 }
1423
1424 /* CHECKME: To clear or not to clear? Mimics normal skb currently */
1425 if (skb_shinfo(skb)->gso_segs <= 1) {
1426 skb_shinfo(skb)->gso_size = 0;
1427 skb_shinfo(skb)->gso_type = 0;
1428 }
1429
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001430 /* We discard results */
Ilpo Järvinen9ec06ff2009-03-01 00:21:36 -08001431 tcp_sacktag_one(skb, sk, state, dup_sack, pcount);
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001432
1433 /* Difference in this won't matter, both ACKed by the same cumul. ACK */
1434 TCP_SKB_CB(prev)->sacked |= (TCP_SKB_CB(skb)->sacked & TCPCB_EVER_RETRANS);
1435
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001436 if (skb->len > 0) {
1437 BUG_ON(!tcp_skb_pcount(skb));
Ilpo Järvinen111cc8b2008-11-24 21:27:22 -08001438 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKSHIFTED);
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001439 return 0;
1440 }
1441
1442 /* Whole SKB was eaten :-) */
1443
Ilpo Järvinen92ee76b2008-11-24 21:26:56 -08001444 if (skb == tp->retransmit_skb_hint)
1445 tp->retransmit_skb_hint = prev;
1446 if (skb == tp->scoreboard_skb_hint)
1447 tp->scoreboard_skb_hint = prev;
1448 if (skb == tp->lost_skb_hint) {
1449 tp->lost_skb_hint = prev;
1450 tp->lost_cnt_hint -= tcp_skb_pcount(prev);
1451 }
1452
Eric Dumazet4de075e2011-09-27 13:25:05 -04001453 TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(prev)->tcp_flags;
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001454 if (skb == tcp_highest_sack(sk))
1455 tcp_advance_highest_sack(sk, skb);
1456
1457 tcp_unlink_write_queue(skb, sk);
1458 sk_wmem_free_skb(sk, skb);
1459
Ilpo Järvinen111cc8b2008-11-24 21:27:22 -08001460 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKMERGED);
1461
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001462 return 1;
1463}
1464
1465/* I wish gso_size would have a bit more sane initialization than
1466 * something-or-zero which complicates things
1467 */
Eric Dumazetcf533ea2011-10-21 05:22:42 -04001468static int tcp_skb_seglen(const struct sk_buff *skb)
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001469{
Ilpo Järvinen775ffab2008-12-05 22:41:26 -08001470 return tcp_skb_pcount(skb) == 1 ? skb->len : tcp_skb_mss(skb);
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001471}
1472
1473/* Shifting pages past head area doesn't work */
Eric Dumazetcf533ea2011-10-21 05:22:42 -04001474static int skb_can_shift(const struct sk_buff *skb)
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001475{
1476 return !skb_headlen(skb) && skb_is_nonlinear(skb);
1477}
1478
1479/* Try collapsing SACK blocks spanning across multiple skbs to a single
1480 * skb.
1481 */
1482static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001483 struct tcp_sacktag_state *state,
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001484 u32 start_seq, u32 end_seq,
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001485 int dup_sack)
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001486{
1487 struct tcp_sock *tp = tcp_sk(sk);
1488 struct sk_buff *prev;
1489 int mss;
1490 int pcount = 0;
1491 int len;
1492 int in_sack;
1493
1494 if (!sk_can_gso(sk))
1495 goto fallback;
1496
1497 /* Normally R but no L won't result in plain S */
1498 if (!dup_sack &&
Ilpo Järvinen9969ca52008-12-05 22:41:06 -08001499 (TCP_SKB_CB(skb)->sacked & (TCPCB_LOST|TCPCB_SACKED_RETRANS)) == TCPCB_SACKED_RETRANS)
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001500 goto fallback;
1501 if (!skb_can_shift(skb))
1502 goto fallback;
1503 /* This frame is about to be dropped (was ACKed). */
1504 if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una))
1505 goto fallback;
1506
1507 /* Can only happen with delayed DSACK + discard craziness */
1508 if (unlikely(skb == tcp_write_queue_head(sk)))
1509 goto fallback;
1510 prev = tcp_write_queue_prev(sk, skb);
1511
1512 if ((TCP_SKB_CB(prev)->sacked & TCPCB_TAGBITS) != TCPCB_SACKED_ACKED)
1513 goto fallback;
1514
1515 in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq) &&
1516 !before(end_seq, TCP_SKB_CB(skb)->end_seq);
1517
1518 if (in_sack) {
1519 len = skb->len;
1520 pcount = tcp_skb_pcount(skb);
Ilpo Järvinen775ffab2008-12-05 22:41:26 -08001521 mss = tcp_skb_seglen(skb);
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001522
1523 /* TODO: Fix DSACKs to not fragment already SACKed and we can
1524 * drop this restriction as unnecessary
1525 */
Ilpo Järvinen775ffab2008-12-05 22:41:26 -08001526 if (mss != tcp_skb_seglen(prev))
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001527 goto fallback;
1528 } else {
1529 if (!after(TCP_SKB_CB(skb)->end_seq, start_seq))
1530 goto noop;
1531 /* CHECKME: This is non-MSS split case only?, this will
1532 * cause skipped skbs due to advancing loop btw, original
1533 * has that feature too
1534 */
1535 if (tcp_skb_pcount(skb) <= 1)
1536 goto noop;
1537
1538 in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq);
1539 if (!in_sack) {
1540 /* TODO: head merge to next could be attempted here
1541 * if (!after(TCP_SKB_CB(skb)->end_seq, end_seq)),
1542 * though it might not be worth of the additional hassle
1543 *
1544 * ...we can probably just fallback to what was done
1545 * previously. We could try merging non-SACKed ones
1546 * as well but it probably isn't going to buy off
1547 * because later SACKs might again split them, and
1548 * it would make skb timestamp tracking considerably
1549 * harder problem.
1550 */
1551 goto fallback;
1552 }
1553
1554 len = end_seq - TCP_SKB_CB(skb)->seq;
1555 BUG_ON(len < 0);
1556 BUG_ON(len > skb->len);
1557
1558 /* MSS boundaries should be honoured or else pcount will
1559 * severely break even though it makes things bit trickier.
1560 * Optimize common case to avoid most of the divides
1561 */
1562 mss = tcp_skb_mss(skb);
1563
1564 /* TODO: Fix DSACKs to not fragment already SACKed and we can
1565 * drop this restriction as unnecessary
1566 */
Ilpo Järvinen775ffab2008-12-05 22:41:26 -08001567 if (mss != tcp_skb_seglen(prev))
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001568 goto fallback;
1569
1570 if (len == mss) {
1571 pcount = 1;
1572 } else if (len < mss) {
1573 goto noop;
1574 } else {
1575 pcount = len / mss;
1576 len = pcount * mss;
1577 }
1578 }
1579
1580 if (!skb_shift(prev, skb, len))
1581 goto fallback;
Ilpo Järvinen9ec06ff2009-03-01 00:21:36 -08001582 if (!tcp_shifted_skb(sk, skb, state, pcount, len, mss, dup_sack))
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001583 goto out;
1584
1585 /* Hole filled allows collapsing with the next as well, this is very
1586 * useful when hole on every nth skb pattern happens
1587 */
1588 if (prev == tcp_write_queue_tail(sk))
1589 goto out;
1590 skb = tcp_write_queue_next(sk, prev);
1591
Ilpo Järvinenf0bc52f2008-12-05 22:40:47 -08001592 if (!skb_can_shift(skb) ||
1593 (skb == tcp_send_head(sk)) ||
1594 ((TCP_SKB_CB(skb)->sacked & TCPCB_TAGBITS) != TCPCB_SACKED_ACKED) ||
Ilpo Järvinen775ffab2008-12-05 22:41:26 -08001595 (mss != tcp_skb_seglen(skb)))
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001596 goto out;
1597
1598 len = skb->len;
1599 if (skb_shift(prev, skb, len)) {
1600 pcount += tcp_skb_pcount(skb);
Ilpo Järvinen9ec06ff2009-03-01 00:21:36 -08001601 tcp_shifted_skb(sk, skb, state, tcp_skb_pcount(skb), len, mss, 0);
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001602 }
1603
1604out:
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001605 state->fack_count += pcount;
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001606 return prev;
1607
1608noop:
1609 return skb;
1610
1611fallback:
Ilpo Järvinen111cc8b2008-11-24 21:27:22 -08001612 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKSHIFTFALLBACK);
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001613 return NULL;
1614}
1615
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001616static struct sk_buff *tcp_sacktag_walk(struct sk_buff *skb, struct sock *sk,
1617 struct tcp_sack_block *next_dup,
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001618 struct tcp_sacktag_state *state,
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001619 u32 start_seq, u32 end_seq,
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001620 int dup_sack_in)
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001621{
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001622 struct tcp_sock *tp = tcp_sk(sk);
1623 struct sk_buff *tmp;
1624
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001625 tcp_for_write_queue_from(skb, sk) {
1626 int in_sack = 0;
1627 int dup_sack = dup_sack_in;
1628
1629 if (skb == tcp_send_head(sk))
1630 break;
1631
1632 /* queue is in-order => we can short-circuit the walk early */
1633 if (!before(TCP_SKB_CB(skb)->seq, end_seq))
1634 break;
1635
1636 if ((next_dup != NULL) &&
1637 before(TCP_SKB_CB(skb)->seq, next_dup->end_seq)) {
1638 in_sack = tcp_match_skb_to_sack(sk, skb,
1639 next_dup->start_seq,
1640 next_dup->end_seq);
1641 if (in_sack > 0)
1642 dup_sack = 1;
1643 }
1644
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001645 /* skb reference here is a bit tricky to get right, since
1646 * shifting can eat and free both this skb and the next,
1647 * so not even _safe variant of the loop is enough.
1648 */
1649 if (in_sack <= 0) {
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001650 tmp = tcp_shift_skb_data(sk, skb, state,
1651 start_seq, end_seq, dup_sack);
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001652 if (tmp != NULL) {
1653 if (tmp != skb) {
1654 skb = tmp;
1655 continue;
1656 }
1657
1658 in_sack = 0;
1659 } else {
1660 in_sack = tcp_match_skb_to_sack(sk, skb,
1661 start_seq,
1662 end_seq);
1663 }
1664 }
1665
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001666 if (unlikely(in_sack < 0))
1667 break;
1668
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001669 if (in_sack) {
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001670 TCP_SKB_CB(skb)->sacked = tcp_sacktag_one(skb, sk,
1671 state,
1672 dup_sack,
1673 tcp_skb_pcount(skb));
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001674
Ilpo Järvinen832d11c2008-11-24 21:20:15 -08001675 if (!before(TCP_SKB_CB(skb)->seq,
1676 tcp_highest_sack_seq(tp)))
1677 tcp_advance_highest_sack(sk, skb);
1678 }
1679
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001680 state->fack_count += tcp_skb_pcount(skb);
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001681 }
1682 return skb;
1683}
1684
1685/* Avoid all extra work that is being done by sacktag while walking in
1686 * a normal way
1687 */
1688static struct sk_buff *tcp_sacktag_skip(struct sk_buff *skb, struct sock *sk,
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001689 struct tcp_sacktag_state *state,
1690 u32 skip_to_seq)
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001691{
1692 tcp_for_write_queue_from(skb, sk) {
1693 if (skb == tcp_send_head(sk))
1694 break;
1695
Ilpo Järvinene8bae272008-11-24 21:12:28 -08001696 if (after(TCP_SKB_CB(skb)->end_seq, skip_to_seq))
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001697 break;
Ilpo Järvinend152a7d2008-03-03 12:10:16 -08001698
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001699 state->fack_count += tcp_skb_pcount(skb);
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001700 }
1701 return skb;
1702}
1703
1704static struct sk_buff *tcp_maybe_skipping_dsack(struct sk_buff *skb,
1705 struct sock *sk,
1706 struct tcp_sack_block *next_dup,
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001707 struct tcp_sacktag_state *state,
1708 u32 skip_to_seq)
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001709{
1710 if (next_dup == NULL)
1711 return skb;
1712
1713 if (before(next_dup->start_seq, skip_to_seq)) {
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001714 skb = tcp_sacktag_skip(skb, sk, state, next_dup->start_seq);
1715 skb = tcp_sacktag_walk(skb, sk, NULL, state,
1716 next_dup->start_seq, next_dup->end_seq,
1717 1);
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001718 }
1719
1720 return skb;
1721}
1722
Eric Dumazetcf533ea2011-10-21 05:22:42 -04001723static int tcp_sack_cache_ok(const struct tcp_sock *tp, const struct tcp_sack_block *cache)
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001724{
1725 return cache < tp->recv_sack_cache + ARRAY_SIZE(tp->recv_sack_cache);
1726}
1727
Linus Torvalds1da177e2005-04-16 15:20:36 -07001728static int
Eric Dumazetcf533ea2011-10-21 05:22:42 -04001729tcp_sacktag_write_queue(struct sock *sk, const struct sk_buff *ack_skb,
Ilpo Järvinen056834d2007-12-31 14:57:14 -08001730 u32 prior_snd_una)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731{
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03001732 const struct inet_connection_sock *icsk = inet_csk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001733 struct tcp_sock *tp = tcp_sk(sk);
Eric Dumazetcf533ea2011-10-21 05:22:42 -04001734 const unsigned char *ptr = (skb_transport_header(ack_skb) +
1735 TCP_SKB_CB(ack_skb)->sacked);
Ilpo Järvinenfd6dad62007-11-15 19:49:47 -08001736 struct tcp_sack_block_wire *sp_wire = (struct tcp_sack_block_wire *)(ptr+2);
Adam Langley4389dde2008-07-19 00:07:02 -07001737 struct tcp_sack_block sp[TCP_NUM_SACKS];
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001738 struct tcp_sack_block *cache;
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001739 struct tcp_sacktag_state state;
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001740 struct sk_buff *skb;
Adam Langley4389dde2008-07-19 00:07:02 -07001741 int num_sacks = min(TCP_NUM_SACKS, (ptr[1] - TCPOLEN_SACK_BASE) >> 3);
Ilpo Järvinenfd6dad62007-11-15 19:49:47 -08001742 int used_sacks;
Ilpo Järvinen7769f402007-06-15 15:14:04 -07001743 int found_dup_sack = 0;
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001744 int i, j;
Baruch Evenfda03fb2007-02-04 23:35:57 -08001745 int first_sack_index;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001746
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001747 state.flag = 0;
1748 state.reord = tp->packets_out;
1749
Ilpo Järvinend738cd82007-03-24 21:03:23 -07001750 if (!tp->sacked_out) {
Ilpo Järvinende83c052007-10-07 23:37:55 -07001751 if (WARN_ON(tp->fackets_out))
1752 tp->fackets_out = 0;
Ilpo Järvinen6859d492007-12-02 00:48:06 +02001753 tcp_highest_sack_reset(sk);
Ilpo Järvinend738cd82007-03-24 21:03:23 -07001754 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001755
Pavel Emelyanov1ed83462008-07-16 20:29:51 -07001756 found_dup_sack = tcp_check_dsack(sk, ack_skb, sp_wire,
David S. Millerd06e0212007-06-18 22:43:06 -07001757 num_sacks, prior_snd_una);
1758 if (found_dup_sack)
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001759 state.flag |= FLAG_DSACKING_ACK;
Baruch Even6f746512007-02-04 23:36:42 -08001760
1761 /* Eliminate too old ACKs, but take into
1762 * account more or less fresh ones, they can
1763 * contain valid SACK info.
1764 */
1765 if (before(TCP_SKB_CB(ack_skb)->ack_seq, prior_snd_una - tp->max_window))
1766 return 0;
1767
Ilpo Järvinen96a2d412007-11-14 15:47:18 -08001768 if (!tp->packets_out)
1769 goto out;
1770
Ilpo Järvinenfd6dad62007-11-15 19:49:47 -08001771 used_sacks = 0;
1772 first_sack_index = 0;
1773 for (i = 0; i < num_sacks; i++) {
1774 int dup_sack = !i && found_dup_sack;
1775
Harvey Harrisond3e2ce32008-05-02 16:26:16 -07001776 sp[used_sacks].start_seq = get_unaligned_be32(&sp_wire[i].start_seq);
1777 sp[used_sacks].end_seq = get_unaligned_be32(&sp_wire[i].end_seq);
Ilpo Järvinenfd6dad62007-11-15 19:49:47 -08001778
1779 if (!tcp_is_sackblock_valid(tp, dup_sack,
1780 sp[used_sacks].start_seq,
1781 sp[used_sacks].end_seq)) {
Pavel Emelyanov40b215e2008-07-03 01:05:41 -07001782 int mib_idx;
1783
Ilpo Järvinenfd6dad62007-11-15 19:49:47 -08001784 if (dup_sack) {
1785 if (!tp->undo_marker)
Pavel Emelyanov40b215e2008-07-03 01:05:41 -07001786 mib_idx = LINUX_MIB_TCPDSACKIGNOREDNOUNDO;
Ilpo Järvinenfd6dad62007-11-15 19:49:47 -08001787 else
Pavel Emelyanov40b215e2008-07-03 01:05:41 -07001788 mib_idx = LINUX_MIB_TCPDSACKIGNOREDOLD;
Ilpo Järvinenfd6dad62007-11-15 19:49:47 -08001789 } else {
1790 /* Don't count olds caused by ACK reordering */
1791 if ((TCP_SKB_CB(ack_skb)->ack_seq != tp->snd_una) &&
1792 !after(sp[used_sacks].end_seq, tp->snd_una))
1793 continue;
Pavel Emelyanov40b215e2008-07-03 01:05:41 -07001794 mib_idx = LINUX_MIB_TCPSACKDISCARD;
Ilpo Järvinenfd6dad62007-11-15 19:49:47 -08001795 }
Pavel Emelyanov40b215e2008-07-03 01:05:41 -07001796
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07001797 NET_INC_STATS_BH(sock_net(sk), mib_idx);
Ilpo Järvinenfd6dad62007-11-15 19:49:47 -08001798 if (i == 0)
1799 first_sack_index = -1;
1800 continue;
1801 }
1802
1803 /* Ignore very old stuff early */
1804 if (!after(sp[used_sacks].end_seq, prior_snd_una))
1805 continue;
1806
1807 used_sacks++;
1808 }
1809
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001810 /* order SACK blocks to allow in order walk of the retrans queue */
1811 for (i = used_sacks - 1; i > 0; i--) {
Ilpo Järvinen056834d2007-12-31 14:57:14 -08001812 for (j = 0; j < i; j++) {
1813 if (after(sp[j].start_seq, sp[j + 1].start_seq)) {
Ilpo Järvinena0bffff2009-03-21 13:36:17 -07001814 swap(sp[j], sp[j + 1]);
Stephen Hemminger6a438bb2005-11-10 17:14:59 -08001815
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001816 /* Track where the first SACK block goes to */
1817 if (j == first_sack_index)
Ilpo Järvinen056834d2007-12-31 14:57:14 -08001818 first_sack_index = j + 1;
Stephen Hemminger6a438bb2005-11-10 17:14:59 -08001819 }
1820 }
1821 }
1822
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001823 skb = tcp_write_queue_head(sk);
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001824 state.fack_count = 0;
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001825 i = 0;
1826
1827 if (!tp->sacked_out) {
1828 /* It's already past, so skip checking against it */
1829 cache = tp->recv_sack_cache + ARRAY_SIZE(tp->recv_sack_cache);
1830 } else {
1831 cache = tp->recv_sack_cache;
1832 /* Skip empty blocks in at head of the cache */
1833 while (tcp_sack_cache_ok(tp, cache) && !cache->start_seq &&
1834 !cache->end_seq)
1835 cache++;
Baruch Evenfda03fb2007-02-04 23:35:57 -08001836 }
1837
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001838 while (i < used_sacks) {
Ilpo Järvinenfd6dad62007-11-15 19:49:47 -08001839 u32 start_seq = sp[i].start_seq;
1840 u32 end_seq = sp[i].end_seq;
Ilpo Järvinen7769f402007-06-15 15:14:04 -07001841 int dup_sack = (found_dup_sack && (i == first_sack_index));
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001842 struct tcp_sack_block *next_dup = NULL;
Ilpo Järvinene56d6cd2007-11-01 00:09:37 -07001843
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001844 if (found_dup_sack && ((i + 1) == first_sack_index))
1845 next_dup = &sp[i + 1];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001846
1847 /* Event "B" in the comment above. */
1848 if (after(end_seq, tp->high_seq))
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001849 state.flag |= FLAG_DATA_LOST;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001850
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001851 /* Skip too early cached blocks */
1852 while (tcp_sack_cache_ok(tp, cache) &&
1853 !before(start_seq, cache->end_seq))
1854 cache++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001855
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001856 /* Can skip some work by looking recv_sack_cache? */
1857 if (tcp_sack_cache_ok(tp, cache) && !dup_sack &&
1858 after(end_seq, cache->start_seq)) {
David S. Millerfe067e82007-03-07 12:12:44 -08001859
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001860 /* Head todo? */
1861 if (before(start_seq, cache->start_seq)) {
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001862 skb = tcp_sacktag_skip(skb, sk, &state,
1863 start_seq);
Ilpo Järvinen056834d2007-12-31 14:57:14 -08001864 skb = tcp_sacktag_walk(skb, sk, next_dup,
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001865 &state,
Ilpo Järvinen056834d2007-12-31 14:57:14 -08001866 start_seq,
1867 cache->start_seq,
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001868 dup_sack);
Baruch Evenfda03fb2007-02-04 23:35:57 -08001869 }
Stephen Hemminger6a438bb2005-11-10 17:14:59 -08001870
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001871 /* Rest of the block already fully processed? */
Ilpo Järvinen20de20b2007-11-16 16:17:05 -08001872 if (!after(end_seq, cache->end_seq))
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001873 goto advance_sp;
Ilpo Järvinen20de20b2007-11-16 16:17:05 -08001874
Ilpo Järvinen056834d2007-12-31 14:57:14 -08001875 skb = tcp_maybe_skipping_dsack(skb, sk, next_dup,
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001876 &state,
1877 cache->end_seq);
Ilpo Järvinene56d6cd2007-11-01 00:09:37 -07001878
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001879 /* ...tail remains todo... */
Ilpo Järvinen6859d492007-12-02 00:48:06 +02001880 if (tcp_highest_sack_seq(tp) == cache->end_seq) {
Ilpo Järvinen20de20b2007-11-16 16:17:05 -08001881 /* ...but better entrypoint exists! */
Ilpo Järvinen6859d492007-12-02 00:48:06 +02001882 skb = tcp_highest_sack(sk);
1883 if (skb == NULL)
1884 break;
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001885 state.fack_count = tp->fackets_out;
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001886 cache++;
1887 goto walk;
1888 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001889
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001890 skb = tcp_sacktag_skip(skb, sk, &state, cache->end_seq);
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001891 /* Check overlap against next cached too (past this one already) */
1892 cache++;
1893 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001894 }
Ilpo Järvinenfbd52eb2007-11-10 21:24:19 -08001895
Ilpo Järvinen6859d492007-12-02 00:48:06 +02001896 if (!before(start_seq, tcp_highest_sack_seq(tp))) {
1897 skb = tcp_highest_sack(sk);
1898 if (skb == NULL)
1899 break;
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001900 state.fack_count = tp->fackets_out;
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001901 }
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001902 skb = tcp_sacktag_skip(skb, sk, &state, start_seq);
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001903
1904walk:
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001905 skb = tcp_sacktag_walk(skb, sk, next_dup, &state,
1906 start_seq, end_seq, dup_sack);
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001907
1908advance_sp:
Ilpo Järvinenfbd52eb2007-11-10 21:24:19 -08001909 /* SACK enhanced FRTO (RFC4138, Appendix B): Clearing correct
1910 * due to in-order walk
1911 */
1912 if (after(end_seq, tp->frto_highmark))
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001913 state.flag &= ~FLAG_ONLY_ORIG_SACKED;
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001914
1915 i++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001916 }
1917
Ilpo Järvinen68f83532007-11-15 19:50:37 -08001918 /* Clear the head of the cache sack blocks so we can skip it next time */
1919 for (i = 0; i < ARRAY_SIZE(tp->recv_sack_cache) - used_sacks; i++) {
1920 tp->recv_sack_cache[i].start_seq = 0;
1921 tp->recv_sack_cache[i].end_seq = 0;
1922 }
1923 for (j = 0; j < used_sacks; j++)
1924 tp->recv_sack_cache[i++] = sp[j];
1925
Ilpo Järvinen407ef1d2007-12-02 00:47:57 +02001926 tcp_mark_lost_retrans(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001927
Ilpo Järvinen86426c22007-08-09 14:45:17 +03001928 tcp_verify_left_out(tp);
1929
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001930 if ((state.reord < tp->fackets_out) &&
Ilpo Järvinenf5771112007-11-15 19:35:11 -08001931 ((icsk->icsk_ca_state != TCP_CA_Loss) || tp->undo_marker) &&
Ilpo Järvinenc5e7af02007-02-23 16:22:06 -08001932 (!tp->frto_highmark || after(tp->snd_una, tp->frto_highmark)))
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001933 tcp_update_reordering(sk, tp->fackets_out - state.reord, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001934
Ilpo Järvinen96a2d412007-11-14 15:47:18 -08001935out:
1936
Linus Torvalds1da177e2005-04-16 15:20:36 -07001937#if FASTRETRANS_DEBUG > 0
Ilpo Järvinen547b7922008-07-25 21:43:18 -07001938 WARN_ON((int)tp->sacked_out < 0);
1939 WARN_ON((int)tp->lost_out < 0);
1940 WARN_ON((int)tp->retrans_out < 0);
1941 WARN_ON((int)tcp_packets_in_flight(tp) < 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001942#endif
Ilpo Järvinena1197f52008-12-05 22:42:22 -08001943 return state.flag;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001944}
1945
Ilpo Järvinen882beba2008-04-07 22:33:07 -07001946/* Limits sacked_out so that sum with lost_out isn't ever larger than
1947 * packets_out. Returns zero if sacked_out adjustement wasn't necessary.
Ilpo Järvinen30935cf2007-02-21 23:01:36 -08001948 */
Ilpo Järvinen8eecaba2008-11-25 13:45:29 -08001949static int tcp_limit_reno_sacked(struct tcp_sock *tp)
Ilpo Järvinen4ddf6672007-05-27 01:52:00 -07001950{
Ilpo Järvinen4ddf6672007-05-27 01:52:00 -07001951 u32 holes;
1952
1953 holes = max(tp->lost_out, 1U);
1954 holes = min(holes, tp->packets_out);
1955
1956 if ((tp->sacked_out + holes) > tp->packets_out) {
1957 tp->sacked_out = tp->packets_out - holes;
Ilpo Järvinen882beba2008-04-07 22:33:07 -07001958 return 1;
Ilpo Järvinen4ddf6672007-05-27 01:52:00 -07001959 }
Ilpo Järvinen882beba2008-04-07 22:33:07 -07001960 return 0;
1961}
1962
1963/* If we receive more dupacks than we expected counting segments
1964 * in assumption of absent reordering, interpret this as reordering.
1965 * The only another reason could be bug in receiver TCP.
1966 */
1967static void tcp_check_reno_reordering(struct sock *sk, const int addend)
1968{
1969 struct tcp_sock *tp = tcp_sk(sk);
1970 if (tcp_limit_reno_sacked(tp))
1971 tcp_update_reordering(sk, tp->packets_out + addend, 0);
Ilpo Järvinen4ddf6672007-05-27 01:52:00 -07001972}
1973
1974/* Emulate SACKs for SACKless connection: account for a new dupack. */
1975
1976static void tcp_add_reno_sack(struct sock *sk)
1977{
1978 struct tcp_sock *tp = tcp_sk(sk);
1979 tp->sacked_out++;
1980 tcp_check_reno_reordering(sk, 0);
Ilpo Järvinen005903b2007-08-09 14:44:16 +03001981 tcp_verify_left_out(tp);
Ilpo Järvinen4ddf6672007-05-27 01:52:00 -07001982}
1983
1984/* Account for ACK, ACKing some data in Reno Recovery phase. */
1985
1986static void tcp_remove_reno_sacks(struct sock *sk, int acked)
1987{
1988 struct tcp_sock *tp = tcp_sk(sk);
1989
1990 if (acked > 0) {
1991 /* One ACK acked hole. The rest eat duplicate ACKs. */
Ilpo Järvinen056834d2007-12-31 14:57:14 -08001992 if (acked - 1 >= tp->sacked_out)
Ilpo Järvinen4ddf6672007-05-27 01:52:00 -07001993 tp->sacked_out = 0;
1994 else
Ilpo Järvinen056834d2007-12-31 14:57:14 -08001995 tp->sacked_out -= acked - 1;
Ilpo Järvinen4ddf6672007-05-27 01:52:00 -07001996 }
1997 tcp_check_reno_reordering(sk, acked);
Ilpo Järvinen005903b2007-08-09 14:44:16 +03001998 tcp_verify_left_out(tp);
Ilpo Järvinen4ddf6672007-05-27 01:52:00 -07001999}
2000
2001static inline void tcp_reset_reno_sack(struct tcp_sock *tp)
2002{
2003 tp->sacked_out = 0;
Ilpo Järvinen4ddf6672007-05-27 01:52:00 -07002004}
2005
Ilpo Järvinen62ab2222008-05-08 01:09:11 -07002006static int tcp_is_sackfrto(const struct tcp_sock *tp)
2007{
2008 return (sysctl_tcp_frto == 0x2) && !tcp_is_reno(tp);
2009}
2010
Ilpo Järvinen95eacd22007-10-01 15:27:42 -07002011/* F-RTO can only be used if TCP has never retransmitted anything other than
2012 * head (SACK enhanced variant from Appendix B of RFC4138 is more robust here)
2013 */
Ilpo Järvinen46d0de42007-02-21 23:10:39 -08002014int tcp_use_frto(struct sock *sk)
Ilpo Järvinenbdaae172007-02-21 22:59:58 -08002015{
2016 const struct tcp_sock *tp = tcp_sk(sk);
Ilpo Järvinen6adb4f72008-04-07 22:33:57 -07002017 const struct inet_connection_sock *icsk = inet_csk(sk);
Ilpo Järvinen46d0de42007-02-21 23:10:39 -08002018 struct sk_buff *skb;
Ilpo Järvinenbdaae172007-02-21 22:59:58 -08002019
Ilpo Järvinen575ee712007-04-30 00:39:55 -07002020 if (!sysctl_tcp_frto)
Ilpo Järvinen46d0de42007-02-21 23:10:39 -08002021 return 0;
2022
Ilpo Järvinen6adb4f72008-04-07 22:33:57 -07002023 /* MTU probe and F-RTO won't really play nicely along currently */
2024 if (icsk->icsk_mtup.probe_size)
2025 return 0;
2026
Ilpo Järvinen62ab2222008-05-08 01:09:11 -07002027 if (tcp_is_sackfrto(tp))
Ilpo Järvinen4dc26652007-02-21 23:16:11 -08002028 return 1;
2029
Ilpo Järvinen46d0de42007-02-21 23:10:39 -08002030 /* Avoid expensive walking of rexmit queue if possible */
2031 if (tp->retrans_out > 1)
2032 return 0;
2033
David S. Millerfe067e82007-03-07 12:12:44 -08002034 skb = tcp_write_queue_head(sk);
David S. Miller28e34872008-09-23 02:51:41 -07002035 if (tcp_skb_is_last(sk, skb))
2036 return 1;
David S. Millerfe067e82007-03-07 12:12:44 -08002037 skb = tcp_write_queue_next(sk, skb); /* Skips head */
2038 tcp_for_write_queue_from(skb, sk) {
2039 if (skb == tcp_send_head(sk))
2040 break;
Ilpo Järvinen056834d2007-12-31 14:57:14 -08002041 if (TCP_SKB_CB(skb)->sacked & TCPCB_RETRANS)
Ilpo Järvinen46d0de42007-02-21 23:10:39 -08002042 return 0;
2043 /* Short-circuit when first non-SACKed skb has been checked */
Ilpo Järvinen056834d2007-12-31 14:57:14 -08002044 if (!(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))
Ilpo Järvinen46d0de42007-02-21 23:10:39 -08002045 break;
2046 }
2047 return 1;
Ilpo Järvinenbdaae172007-02-21 22:59:58 -08002048}
2049
Ilpo Järvinen30935cf2007-02-21 23:01:36 -08002050/* RTO occurred, but do not yet enter Loss state. Instead, defer RTO
2051 * recovery a bit and use heuristics in tcp_process_frto() to detect if
Ilpo Järvinend1a54c62007-02-21 23:11:57 -08002052 * the RTO was spurious. Only clear SACKED_RETRANS of the head here to
2053 * keep retrans_out counting accurate (with SACK F-RTO, other than head
2054 * may still have that bit set); TCPCB_LOST and remaining SACKED_RETRANS
2055 * bits are handled if the Loss state is really to be entered (in
2056 * tcp_enter_frto_loss).
Ilpo Järvinen7487c482007-02-21 23:02:30 -08002057 *
2058 * Do like tcp_enter_loss() would; when RTO expires the second time it
2059 * does:
2060 * "Reduce ssthresh if it has not yet been made inside this window."
Linus Torvalds1da177e2005-04-16 15:20:36 -07002061 */
2062void tcp_enter_frto(struct sock *sk)
2063{
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002064 const struct inet_connection_sock *icsk = inet_csk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002065 struct tcp_sock *tp = tcp_sk(sk);
2066 struct sk_buff *skb;
2067
Ilpo Järvinen7487c482007-02-21 23:02:30 -08002068 if ((!tp->frto_counter && icsk->icsk_ca_state <= TCP_CA_Disorder) ||
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09002069 tp->snd_una == tp->high_seq ||
Ilpo Järvinen7487c482007-02-21 23:02:30 -08002070 ((icsk->icsk_ca_state == TCP_CA_Loss || tp->frto_counter) &&
2071 !icsk->icsk_retransmits)) {
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002072 tp->prior_ssthresh = tcp_current_ssthresh(sk);
Ilpo Järvinen66e93e42007-02-21 23:13:47 -08002073 /* Our state is too optimistic in ssthresh() call because cwnd
Ryousei Takano564262c12007-10-25 23:03:52 -07002074 * is not reduced until tcp_enter_frto_loss() when previous F-RTO
Ilpo Järvinen66e93e42007-02-21 23:13:47 -08002075 * recovery has not yet completed. Pattern would be this: RTO,
2076 * Cumulative ACK, RTO (2xRTO for the same segment does not end
2077 * up here twice).
2078 * RFC4138 should be more specific on what to do, even though
2079 * RTO is quite unlikely to occur after the first Cumulative ACK
2080 * due to back-off and complexity of triggering events ...
2081 */
2082 if (tp->frto_counter) {
2083 u32 stored_cwnd;
2084 stored_cwnd = tp->snd_cwnd;
2085 tp->snd_cwnd = 2;
2086 tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk);
2087 tp->snd_cwnd = stored_cwnd;
2088 } else {
2089 tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk);
2090 }
2091 /* ... in theory, cong.control module could do "any tricks" in
2092 * ssthresh(), which means that ca_state, lost bits and lost_out
2093 * counter would have to be faked before the call occurs. We
2094 * consider that too expensive, unlikely and hacky, so modules
2095 * using these in ssthresh() must deal these incompatibility
2096 * issues if they receives CA_EVENT_FRTO and frto_counter != 0
2097 */
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002098 tcp_ca_event(sk, CA_EVENT_FRTO);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002099 }
2100
Linus Torvalds1da177e2005-04-16 15:20:36 -07002101 tp->undo_marker = tp->snd_una;
2102 tp->undo_retrans = 0;
2103
David S. Millerfe067e82007-03-07 12:12:44 -08002104 skb = tcp_write_queue_head(sk);
Ilpo Järvinen009a2e32007-09-20 11:34:38 -07002105 if (TCP_SKB_CB(skb)->sacked & TCPCB_RETRANS)
2106 tp->undo_marker = 0;
Ilpo Järvinend1a54c62007-02-21 23:11:57 -08002107 if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) {
Ilpo Järvinen522e7542007-02-21 22:54:52 -08002108 TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
Ilpo Järvinend1a54c62007-02-21 23:11:57 -08002109 tp->retrans_out -= tcp_skb_pcount(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002110 }
Ilpo Järvinen005903b2007-08-09 14:44:16 +03002111 tcp_verify_left_out(tp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002112
Ilpo Järvinen746aa322007-11-13 21:01:23 -08002113 /* Too bad if TCP was application limited */
2114 tp->snd_cwnd = min(tp->snd_cwnd, tcp_packets_in_flight(tp) + 1);
2115
Ilpo Järvinen4dc26652007-02-21 23:16:11 -08002116 /* Earlier loss recovery underway (see RFC4138; Appendix B).
2117 * The last condition is necessary at least in tp->frto_counter case.
2118 */
Ilpo Järvinen62ab2222008-05-08 01:09:11 -07002119 if (tcp_is_sackfrto(tp) && (tp->frto_counter ||
Ilpo Järvinen4dc26652007-02-21 23:16:11 -08002120 ((1 << icsk->icsk_ca_state) & (TCPF_CA_Recovery|TCPF_CA_Loss))) &&
2121 after(tp->high_seq, tp->snd_una)) {
2122 tp->frto_highmark = tp->high_seq;
2123 } else {
2124 tp->frto_highmark = tp->snd_nxt;
2125 }
Ilpo Järvinen7b0eb222007-02-21 23:03:35 -08002126 tcp_set_ca_state(sk, TCP_CA_Disorder);
2127 tp->high_seq = tp->snd_nxt;
Ilpo Järvinen7487c482007-02-21 23:02:30 -08002128 tp->frto_counter = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002129}
2130
2131/* Enter Loss state after F-RTO was applied. Dupack arrived after RTO,
2132 * which indicates that we should follow the traditional RTO recovery,
2133 * i.e. mark everything lost and do go-back-N retransmission.
2134 */
Ilpo Järvinend1a54c62007-02-21 23:11:57 -08002135static void tcp_enter_frto_loss(struct sock *sk, int allowed_segments, int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002136{
2137 struct tcp_sock *tp = tcp_sk(sk);
2138 struct sk_buff *skb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002139
Linus Torvalds1da177e2005-04-16 15:20:36 -07002140 tp->lost_out = 0;
Ilpo Järvinend1a54c62007-02-21 23:11:57 -08002141 tp->retrans_out = 0;
Ilpo Järvinene60402d2007-08-09 15:14:46 +03002142 if (tcp_is_reno(tp))
Ilpo Järvinen9bff40f2007-05-27 01:53:49 -07002143 tcp_reset_reno_sack(tp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002144
David S. Millerfe067e82007-03-07 12:12:44 -08002145 tcp_for_write_queue(skb, sk) {
2146 if (skb == tcp_send_head(sk))
2147 break;
Ilpo Järvinen23aeeec2007-11-13 21:03:13 -08002148
2149 TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
Ilpo Järvinend1a54c62007-02-21 23:11:57 -08002150 /*
2151 * Count the retransmission made on RTO correctly (only when
2152 * waiting for the first ACK and did not get it)...
2153 */
Ilpo Järvinen056834d2007-12-31 14:57:14 -08002154 if ((tp->frto_counter == 1) && !(flag & FLAG_DATA_ACKED)) {
Ilpo Järvinen0a9f2a42007-07-15 00:19:29 -07002155 /* For some reason this R-bit might get cleared? */
2156 if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)
2157 tp->retrans_out += tcp_skb_pcount(skb);
Ilpo Järvinend1a54c62007-02-21 23:11:57 -08002158 /* ...enter this if branch just for the first segment */
2159 flag |= FLAG_DATA_ACKED;
2160 } else {
Ilpo Järvinen009a2e32007-09-20 11:34:38 -07002161 if (TCP_SKB_CB(skb)->sacked & TCPCB_RETRANS)
2162 tp->undo_marker = 0;
Ilpo Järvinen23aeeec2007-11-13 21:03:13 -08002163 TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
Ilpo Järvinend1a54c62007-02-21 23:11:57 -08002164 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165
Ilpo Järvinen79d445162008-05-13 02:54:19 -07002166 /* Marking forward transmissions that were made after RTO lost
2167 * can cause unnecessary retransmissions in some scenarios,
2168 * SACK blocks will mitigate that in some but not in all cases.
2169 * We used to not mark them but it was causing break-ups with
2170 * receivers that do only in-order receival.
2171 *
2172 * TODO: we could detect presence of such receiver and select
2173 * different behavior per flow.
2174 */
2175 if (!(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) {
Ilpo Järvinen9bff40f2007-05-27 01:53:49 -07002176 TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
2177 tp->lost_out += tcp_skb_pcount(skb);
Ilpo Järvinen006f5822008-09-20 21:20:20 -07002178 tp->retransmit_high = TCP_SKB_CB(skb)->end_seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002179 }
2180 }
Ilpo Järvinen005903b2007-08-09 14:44:16 +03002181 tcp_verify_left_out(tp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002182
Ilpo Järvinen95c49222007-02-21 23:05:18 -08002183 tp->snd_cwnd = tcp_packets_in_flight(tp) + allowed_segments;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002184 tp->snd_cwnd_cnt = 0;
2185 tp->snd_cwnd_stamp = tcp_time_stamp;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002186 tp->frto_counter = 0;
Ilpo Järvinen16e90682007-10-11 17:32:31 -07002187 tp->bytes_acked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002188
2189 tp->reordering = min_t(unsigned int, tp->reordering,
Ilpo Järvinen056834d2007-12-31 14:57:14 -08002190 sysctl_tcp_reordering);
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002191 tcp_set_ca_state(sk, TCP_CA_Loss);
Ilpo Järvinen79d445162008-05-13 02:54:19 -07002192 tp->high_seq = tp->snd_nxt;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002193 TCP_ECN_queue_cwr(tp);
Stephen Hemminger6a438bb2005-11-10 17:14:59 -08002194
Ilpo Järvinen64edc272008-09-20 21:18:32 -07002195 tcp_clear_all_retrans_hints(tp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002196}
2197
Ilpo Järvinen4cd82992007-10-11 17:34:57 -07002198static void tcp_clear_retrans_partial(struct tcp_sock *tp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002199{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002200 tp->retrans_out = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002201 tp->lost_out = 0;
2202
2203 tp->undo_marker = 0;
2204 tp->undo_retrans = 0;
2205}
2206
Ilpo Järvinen4cd82992007-10-11 17:34:57 -07002207void tcp_clear_retrans(struct tcp_sock *tp)
2208{
2209 tcp_clear_retrans_partial(tp);
2210
2211 tp->fackets_out = 0;
2212 tp->sacked_out = 0;
2213}
2214
Linus Torvalds1da177e2005-04-16 15:20:36 -07002215/* Enter Loss state. If "how" is not zero, forget all SACK information
2216 * and reset tags completely, otherwise preserve SACKs. If receiver
2217 * dropped its ofo queue, we will know this due to reneging detection.
2218 */
2219void tcp_enter_loss(struct sock *sk, int how)
2220{
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002221 const struct inet_connection_sock *icsk = inet_csk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002222 struct tcp_sock *tp = tcp_sk(sk);
2223 struct sk_buff *skb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002224
2225 /* Reduce ssthresh if it has not yet been made inside this window. */
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002226 if (icsk->icsk_ca_state <= TCP_CA_Disorder || tp->snd_una == tp->high_seq ||
2227 (icsk->icsk_ca_state == TCP_CA_Loss && !icsk->icsk_retransmits)) {
2228 tp->prior_ssthresh = tcp_current_ssthresh(sk);
2229 tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk);
2230 tcp_ca_event(sk, CA_EVENT_LOSS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002231 }
2232 tp->snd_cwnd = 1;
2233 tp->snd_cwnd_cnt = 0;
2234 tp->snd_cwnd_stamp = tcp_time_stamp;
2235
Stephen Hemminger9772efb2005-11-10 17:09:53 -08002236 tp->bytes_acked = 0;
Ilpo Järvinen4cd82992007-10-11 17:34:57 -07002237 tcp_clear_retrans_partial(tp);
2238
2239 if (tcp_is_reno(tp))
2240 tcp_reset_reno_sack(tp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002241
Ilpo Järvinenb7689202007-09-20 11:37:19 -07002242 if (!how) {
2243 /* Push undo marker, if it was plain RTO and nothing
2244 * was retransmitted. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002245 tp->undo_marker = tp->snd_una;
Ilpo Järvinenb7689202007-09-20 11:37:19 -07002246 } else {
Ilpo Järvinen4cd82992007-10-11 17:34:57 -07002247 tp->sacked_out = 0;
2248 tp->fackets_out = 0;
Ilpo Järvinenb7689202007-09-20 11:37:19 -07002249 }
Ilpo Järvinen64edc272008-09-20 21:18:32 -07002250 tcp_clear_all_retrans_hints(tp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002251
David S. Millerfe067e82007-03-07 12:12:44 -08002252 tcp_for_write_queue(skb, sk) {
2253 if (skb == tcp_send_head(sk))
2254 break;
Ilpo Järvinen4cd82992007-10-11 17:34:57 -07002255
Ilpo Järvinen056834d2007-12-31 14:57:14 -08002256 if (TCP_SKB_CB(skb)->sacked & TCPCB_RETRANS)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002257 tp->undo_marker = 0;
2258 TCP_SKB_CB(skb)->sacked &= (~TCPCB_TAGBITS)|TCPCB_SACKED_ACKED;
2259 if (!(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED) || how) {
2260 TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_ACKED;
2261 TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
2262 tp->lost_out += tcp_skb_pcount(skb);
Ilpo Järvinen006f5822008-09-20 21:20:20 -07002263 tp->retransmit_high = TCP_SKB_CB(skb)->end_seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002264 }
2265 }
Ilpo Järvinen005903b2007-08-09 14:44:16 +03002266 tcp_verify_left_out(tp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002267
2268 tp->reordering = min_t(unsigned int, tp->reordering,
Ilpo Järvinen056834d2007-12-31 14:57:14 -08002269 sysctl_tcp_reordering);
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002270 tcp_set_ca_state(sk, TCP_CA_Loss);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002271 tp->high_seq = tp->snd_nxt;
2272 TCP_ECN_queue_cwr(tp);
Ryousei Takano564262c12007-10-25 23:03:52 -07002273 /* Abort F-RTO algorithm if one is in progress */
Ilpo Järvinen580e5722007-05-19 13:56:57 -07002274 tp->frto_counter = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002275}
2276
Ilpo Järvinencadbd032007-12-31 04:49:21 -08002277/* If ACK arrived pointing to a remembered SACK, it means that our
2278 * remembered SACKs do not reflect real state of receiver i.e.
2279 * receiver _host_ is heavily congested (or buggy).
2280 *
2281 * Do processing similar to RTO timeout.
2282 */
2283static int tcp_check_sack_reneging(struct sock *sk, int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002284{
Ilpo Järvinencadbd032007-12-31 04:49:21 -08002285 if (flag & FLAG_SACK_RENEGING) {
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002286 struct inet_connection_sock *icsk = inet_csk(sk);
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07002287 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSACKRENEGING);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002288
2289 tcp_enter_loss(sk, 1);
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002290 icsk->icsk_retransmits++;
David S. Millerfe067e82007-03-07 12:12:44 -08002291 tcp_retransmit_skb(sk, tcp_write_queue_head(sk));
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07002292 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002293 icsk->icsk_rto, TCP_RTO_MAX);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002294 return 1;
2295 }
2296 return 0;
2297}
2298
Eric Dumazetcf533ea2011-10-21 05:22:42 -04002299static inline int tcp_fackets_out(const struct tcp_sock *tp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002300{
Ilpo Järvinen056834d2007-12-31 14:57:14 -08002301 return tcp_is_reno(tp) ? tp->sacked_out + 1 : tp->fackets_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002302}
2303
Ilpo Järvinen85cc3912007-11-15 19:39:31 -08002304/* Heurestics to calculate number of duplicate ACKs. There's no dupACKs
2305 * counter when SACK is enabled (without SACK, sacked_out is used for
2306 * that purpose).
2307 *
2308 * Instead, with FACK TCP uses fackets_out that includes both SACKed
2309 * segments up to the highest received SACK block so far and holes in
2310 * between them.
2311 *
2312 * With reordering, holes may still be in flight, so RFC3517 recovery
2313 * uses pure sacked_out (total number of SACKed segments) even though
2314 * it violates the RFC that uses duplicate ACKs, often these are equal
2315 * but when e.g. out-of-window ACKs or packet duplication occurs,
2316 * they differ. Since neither occurs due to loss, TCP should really
2317 * ignore them.
2318 */
Eric Dumazetcf533ea2011-10-21 05:22:42 -04002319static inline int tcp_dupack_heuristics(const struct tcp_sock *tp)
Ilpo Järvinen85cc3912007-11-15 19:39:31 -08002320{
2321 return tcp_is_fack(tp) ? tp->fackets_out : tp->sacked_out + 1;
2322}
2323
Eric Dumazetcf533ea2011-10-21 05:22:42 -04002324static inline int tcp_skb_timedout(const struct sock *sk,
2325 const struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002326{
Eric Dumazeta02cec22010-09-22 20:43:57 +00002327 return tcp_time_stamp - TCP_SKB_CB(skb)->when > inet_csk(sk)->icsk_rto;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002328}
2329
Eric Dumazetcf533ea2011-10-21 05:22:42 -04002330static inline int tcp_head_timedout(const struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002331{
Eric Dumazetcf533ea2011-10-21 05:22:42 -04002332 const struct tcp_sock *tp = tcp_sk(sk);
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002333
Linus Torvalds1da177e2005-04-16 15:20:36 -07002334 return tp->packets_out &&
David S. Millerfe067e82007-03-07 12:12:44 -08002335 tcp_skb_timedout(sk, tcp_write_queue_head(sk));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002336}
2337
2338/* Linux NewReno/SACK/FACK/ECN state machine.
2339 * --------------------------------------
2340 *
2341 * "Open" Normal state, no dubious events, fast path.
2342 * "Disorder" In all the respects it is "Open",
2343 * but requires a bit more attention. It is entered when
2344 * we see some SACKs or dupacks. It is split of "Open"
2345 * mainly to move some processing from fast path to slow one.
2346 * "CWR" CWND was reduced due to some Congestion Notification event.
2347 * It can be ECN, ICMP source quench, local device congestion.
2348 * "Recovery" CWND was reduced, we are fast-retransmitting.
2349 * "Loss" CWND was reduced due to RTO timeout or SACK reneging.
2350 *
2351 * tcp_fastretrans_alert() is entered:
2352 * - each incoming ACK, if state is not "Open"
2353 * - when arrived ACK is unusual, namely:
2354 * * SACK
2355 * * Duplicate ACK.
2356 * * ECN ECE.
2357 *
2358 * Counting packets in flight is pretty simple.
2359 *
2360 * in_flight = packets_out - left_out + retrans_out
2361 *
2362 * packets_out is SND.NXT-SND.UNA counted in packets.
2363 *
2364 * retrans_out is number of retransmitted segments.
2365 *
2366 * left_out is number of segments left network, but not ACKed yet.
2367 *
2368 * left_out = sacked_out + lost_out
2369 *
2370 * sacked_out: Packets, which arrived to receiver out of order
2371 * and hence not ACKed. With SACKs this number is simply
2372 * amount of SACKed data. Even without SACKs
2373 * it is easy to give pretty reliable estimate of this number,
2374 * counting duplicate ACKs.
2375 *
2376 * lost_out: Packets lost by network. TCP has no explicit
2377 * "loss notification" feedback from network (for now).
2378 * It means that this number can be only _guessed_.
2379 * Actually, it is the heuristics to predict lossage that
2380 * distinguishes different algorithms.
2381 *
2382 * F.e. after RTO, when all the queue is considered as lost,
2383 * lost_out = packets_out and in_flight = retrans_out.
2384 *
2385 * Essentially, we have now two algorithms counting
2386 * lost packets.
2387 *
2388 * FACK: It is the simplest heuristics. As soon as we decided
2389 * that something is lost, we decide that _all_ not SACKed
2390 * packets until the most forward SACK are lost. I.e.
2391 * lost_out = fackets_out - sacked_out and left_out = fackets_out.
2392 * It is absolutely correct estimate, if network does not reorder
2393 * packets. And it loses any connection to reality when reordering
2394 * takes place. We use FACK by default until reordering
2395 * is suspected on the path to this destination.
2396 *
2397 * NewReno: when Recovery is entered, we assume that one segment
2398 * is lost (classic Reno). While we are in Recovery and
2399 * a partial ACK arrives, we assume that one more packet
2400 * is lost (NewReno). This heuristics are the same in NewReno
2401 * and SACK.
2402 *
2403 * Imagine, that's all! Forget about all this shamanism about CWND inflation
2404 * deflation etc. CWND is real congestion window, never inflated, changes
2405 * only according to classic VJ rules.
2406 *
2407 * Really tricky (and requiring careful tuning) part of algorithm
2408 * is hidden in functions tcp_time_to_recover() and tcp_xmit_retransmit_queue().
2409 * The first determines the moment _when_ we should reduce CWND and,
2410 * hence, slow down forward transmission. In fact, it determines the moment
2411 * when we decide that hole is caused by loss, rather than by a reorder.
2412 *
2413 * tcp_xmit_retransmit_queue() decides, _what_ we should retransmit to fill
2414 * holes, caused by lost packets.
2415 *
2416 * And the most logically complicated part of algorithm is undo
2417 * heuristics. We detect false retransmits due to both too early
2418 * fast retransmit (reordering) and underestimated RTO, analyzing
2419 * timestamps and D-SACKs. When we detect that some segments were
2420 * retransmitted by mistake and CWND reduction was wrong, we undo
2421 * window reduction and abort recovery phase. This logic is hidden
2422 * inside several functions named tcp_try_undo_<something>.
2423 */
2424
2425/* This function decides, when we should leave Disordered state
2426 * and enter Recovery phase, reducing congestion window.
2427 *
2428 * Main question: may we further continue forward transmission
2429 * with the same cwnd?
2430 */
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002431static int tcp_time_to_recover(struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002432{
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002433 struct tcp_sock *tp = tcp_sk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002434 __u32 packets_out;
2435
Ryousei Takano564262c12007-10-25 23:03:52 -07002436 /* Do not perform any recovery during F-RTO algorithm */
Ilpo Järvinen52c63f12007-02-21 23:06:52 -08002437 if (tp->frto_counter)
2438 return 0;
2439
Linus Torvalds1da177e2005-04-16 15:20:36 -07002440 /* Trick#1: The loss is proven. */
2441 if (tp->lost_out)
2442 return 1;
2443
2444 /* Not-A-Trick#2 : Classic rule... */
Andreas Petlundea84e552009-10-27 03:27:21 +00002445 if (tcp_dupack_heuristics(tp) > tp->reordering)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002446 return 1;
2447
2448 /* Trick#3 : when we use RFC2988 timer restart, fast
2449 * retransmit can be triggered by timeout of queue head.
2450 */
Ilpo Järvinen85cc3912007-11-15 19:39:31 -08002451 if (tcp_is_fack(tp) && tcp_head_timedout(sk))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002452 return 1;
2453
2454 /* Trick#4: It is still not OK... But will it be useful to delay
2455 * recovery more?
2456 */
2457 packets_out = tp->packets_out;
2458 if (packets_out <= tp->reordering &&
2459 tp->sacked_out >= max_t(__u32, packets_out/2, sysctl_tcp_reordering) &&
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002460 !tcp_may_send_now(sk)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002461 /* We have nothing to send. This connection is limited
2462 * either by receiver window or by application.
2463 */
2464 return 1;
2465 }
2466
Andreas Petlund7e380172010-02-18 04:48:19 +00002467 /* If a thin stream is detected, retransmit after first
2468 * received dupack. Employ only if SACK is supported in order
2469 * to avoid possible corner-case series of spurious retransmissions
2470 * Use only if there are no unsent data.
2471 */
2472 if ((tp->thin_dupack || sysctl_tcp_thin_dupack) &&
2473 tcp_stream_is_thin(tp) && tcp_dupack_heuristics(tp) > 1 &&
2474 tcp_is_sack(tp) && !tcp_send_head(sk))
2475 return 1;
2476
Linus Torvalds1da177e2005-04-16 15:20:36 -07002477 return 0;
2478}
2479
Ilpo Järvinen7363a5b2009-02-28 04:44:33 +00002480/* New heuristics: it is possible only after we switched to restart timer
2481 * each time when something is ACKed. Hence, we can detect timed out packets
2482 * during fast retransmit without falling to slow start.
2483 *
2484 * Usefulness of this as is very questionable, since we should know which of
2485 * the segments is the next to timeout which is relatively expensive to find
2486 * in general case unless we add some data structure just for that. The
2487 * current approach certainly won't find the right one too often and when it
2488 * finally does find _something_ it usually marks large part of the window
2489 * right away (because a retransmission with a larger timestamp blocks the
2490 * loop from advancing). -ij
2491 */
2492static void tcp_timeout_skbs(struct sock *sk)
2493{
2494 struct tcp_sock *tp = tcp_sk(sk);
2495 struct sk_buff *skb;
2496
2497 if (!tcp_is_fack(tp) || !tcp_head_timedout(sk))
2498 return;
2499
2500 skb = tp->scoreboard_skb_hint;
2501 if (tp->scoreboard_skb_hint == NULL)
2502 skb = tcp_write_queue_head(sk);
2503
2504 tcp_for_write_queue_from(skb, sk) {
2505 if (skb == tcp_send_head(sk))
2506 break;
2507 if (!tcp_skb_timedout(sk, skb))
2508 break;
2509
2510 tcp_skb_mark_lost(tp, skb);
2511 }
2512
2513 tp->scoreboard_skb_hint = skb;
2514
2515 tcp_verify_left_out(tp);
2516}
2517
Ilpo Järvinen85cc3912007-11-15 19:39:31 -08002518/* Mark head of queue up as lost. With RFC3517 SACK, the packets is
2519 * is against sacked "cnt", otherwise it's against facked "cnt"
2520 */
Ilpo Järvinen1fdb9362010-10-14 01:42:30 +00002521static void tcp_mark_head_lost(struct sock *sk, int packets, int mark_head)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002522{
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002523 struct tcp_sock *tp = tcp_sk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002524 struct sk_buff *skb;
Ilpo Järvinenc137f3d2008-04-07 22:32:38 -07002525 int cnt, oldcnt;
2526 int err;
2527 unsigned int mss;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002528
Ilpo Järvinen547b7922008-07-25 21:43:18 -07002529 WARN_ON(packets > tp->packets_out);
Stephen Hemminger6a438bb2005-11-10 17:14:59 -08002530 if (tp->lost_skb_hint) {
2531 skb = tp->lost_skb_hint;
2532 cnt = tp->lost_cnt_hint;
Ilpo Järvinen1fdb9362010-10-14 01:42:30 +00002533 /* Head already handled? */
2534 if (mark_head && skb != tcp_write_queue_head(sk))
2535 return;
Stephen Hemminger6a438bb2005-11-10 17:14:59 -08002536 } else {
David S. Millerfe067e82007-03-07 12:12:44 -08002537 skb = tcp_write_queue_head(sk);
Stephen Hemminger6a438bb2005-11-10 17:14:59 -08002538 cnt = 0;
2539 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002540
David S. Millerfe067e82007-03-07 12:12:44 -08002541 tcp_for_write_queue_from(skb, sk) {
2542 if (skb == tcp_send_head(sk))
2543 break;
Stephen Hemminger6a438bb2005-11-10 17:14:59 -08002544 /* TODO: do this better */
2545 /* this is not the most efficient way to do this... */
2546 tp->lost_skb_hint = skb;
2547 tp->lost_cnt_hint = cnt;
Ilpo Järvinen85cc3912007-11-15 19:39:31 -08002548
Ilpo Järvinenc137f3d2008-04-07 22:32:38 -07002549 if (after(TCP_SKB_CB(skb)->end_seq, tp->high_seq))
2550 break;
2551
2552 oldcnt = cnt;
Ilpo Järvinenad1984e2008-01-30 20:06:02 -08002553 if (tcp_is_fack(tp) || tcp_is_reno(tp) ||
Ilpo Järvinen85cc3912007-11-15 19:39:31 -08002554 (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))
2555 cnt += tcp_skb_pcount(skb);
2556
Ilpo Järvinenc137f3d2008-04-07 22:32:38 -07002557 if (cnt > packets) {
Yuchung Chengb3de7552010-09-24 13:22:06 +00002558 if ((tcp_is_sack(tp) && !tcp_is_fack(tp)) ||
2559 (oldcnt >= packets))
Ilpo Järvinenc137f3d2008-04-07 22:32:38 -07002560 break;
2561
2562 mss = skb_shinfo(skb)->gso_size;
2563 err = tcp_fragment(sk, skb, (packets - oldcnt) * mss, mss);
2564 if (err < 0)
2565 break;
2566 cnt = packets;
2567 }
2568
Ilpo Järvinen41ea36e2008-09-20 21:19:22 -07002569 tcp_skb_mark_lost(tp, skb);
Ilpo Järvinen1fdb9362010-10-14 01:42:30 +00002570
2571 if (mark_head)
2572 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002573 }
Ilpo Järvinen005903b2007-08-09 14:44:16 +03002574 tcp_verify_left_out(tp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002575}
2576
2577/* Account newly detected lost packet(s) */
2578
Ilpo Järvinen85cc3912007-11-15 19:39:31 -08002579static void tcp_update_scoreboard(struct sock *sk, int fast_rexmit)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002580{
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002581 struct tcp_sock *tp = tcp_sk(sk);
2582
Ilpo Järvinen85cc3912007-11-15 19:39:31 -08002583 if (tcp_is_reno(tp)) {
Ilpo Järvinen1fdb9362010-10-14 01:42:30 +00002584 tcp_mark_head_lost(sk, 1, 1);
Ilpo Järvinen85cc3912007-11-15 19:39:31 -08002585 } else if (tcp_is_fack(tp)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002586 int lost = tp->fackets_out - tp->reordering;
2587 if (lost <= 0)
2588 lost = 1;
Ilpo Järvinen1fdb9362010-10-14 01:42:30 +00002589 tcp_mark_head_lost(sk, lost, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002590 } else {
Ilpo Järvinen85cc3912007-11-15 19:39:31 -08002591 int sacked_upto = tp->sacked_out - tp->reordering;
Ilpo Järvinen1fdb9362010-10-14 01:42:30 +00002592 if (sacked_upto >= 0)
2593 tcp_mark_head_lost(sk, sacked_upto, 0);
2594 else if (fast_rexmit)
2595 tcp_mark_head_lost(sk, 1, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002596 }
2597
Ilpo Järvinen7363a5b2009-02-28 04:44:33 +00002598 tcp_timeout_skbs(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002599}
2600
2601/* CWND moderation, preventing bursts due to too big ACKs
2602 * in dubious situations.
2603 */
2604static inline void tcp_moderate_cwnd(struct tcp_sock *tp)
2605{
2606 tp->snd_cwnd = min(tp->snd_cwnd,
Ilpo Järvinen056834d2007-12-31 14:57:14 -08002607 tcp_packets_in_flight(tp) + tcp_max_burst(tp));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002608 tp->snd_cwnd_stamp = tcp_time_stamp;
2609}
2610
Stephen Hemminger72dc5b92006-06-05 17:30:08 -07002611/* Lower bound on congestion window is slow start threshold
2612 * unless congestion avoidance choice decides to overide it.
2613 */
2614static inline u32 tcp_cwnd_min(const struct sock *sk)
2615{
2616 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
2617
2618 return ca_ops->min_cwnd ? ca_ops->min_cwnd(sk) : tcp_sk(sk)->snd_ssthresh;
2619}
2620
Linus Torvalds1da177e2005-04-16 15:20:36 -07002621/* Decrease cwnd each second ack. */
Ilpo Järvinen1e757f92007-07-30 19:48:37 -07002622static void tcp_cwnd_down(struct sock *sk, int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002623{
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002624 struct tcp_sock *tp = tcp_sk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002625 int decr = tp->snd_cwnd_cnt + 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002626
Ilpo Järvinen056834d2007-12-31 14:57:14 -08002627 if ((flag & (FLAG_ANY_PROGRESS | FLAG_DSACKING_ACK)) ||
2628 (tcp_is_reno(tp) && !(flag & FLAG_NOT_DUP))) {
2629 tp->snd_cwnd_cnt = decr & 1;
Ilpo Järvinen1e757f92007-07-30 19:48:37 -07002630 decr >>= 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002631
Ilpo Järvinen1e757f92007-07-30 19:48:37 -07002632 if (decr && tp->snd_cwnd > tcp_cwnd_min(sk))
2633 tp->snd_cwnd -= decr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002634
Ilpo Järvinen056834d2007-12-31 14:57:14 -08002635 tp->snd_cwnd = min(tp->snd_cwnd, tcp_packets_in_flight(tp) + 1);
Ilpo Järvinen1e757f92007-07-30 19:48:37 -07002636 tp->snd_cwnd_stamp = tcp_time_stamp;
2637 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002638}
2639
2640/* Nothing was retransmitted or returned timestamp is less
2641 * than timestamp of the first retransmission.
2642 */
Eric Dumazetcf533ea2011-10-21 05:22:42 -04002643static inline int tcp_packet_delayed(const struct tcp_sock *tp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002644{
2645 return !tp->retrans_stamp ||
2646 (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
Arnd Hannemannd7ee1472008-04-21 14:46:22 -07002647 before(tp->rx_opt.rcv_tsecr, tp->retrans_stamp));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002648}
2649
2650/* Undo procedures. */
2651
2652#if FASTRETRANS_DEBUG > 1
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002653static void DBGUNDO(struct sock *sk, const char *msg)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002654{
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002655 struct tcp_sock *tp = tcp_sk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002656 struct inet_sock *inet = inet_sk(sk);
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002657
YOSHIFUJI Hideaki569508c2008-04-14 04:09:36 -07002658 if (sk->sk_family == AF_INET) {
Harvey Harrison673d57e2008-10-31 00:53:57 -07002659 printk(KERN_DEBUG "Undo %s %pI4/%u c%u l%u ss%u/%u p%u\n",
YOSHIFUJI Hideaki569508c2008-04-14 04:09:36 -07002660 msg,
Joe Perches288fcee2010-05-31 23:48:19 -07002661 &inet->inet_daddr, ntohs(inet->inet_dport),
YOSHIFUJI Hideaki569508c2008-04-14 04:09:36 -07002662 tp->snd_cwnd, tcp_left_out(tp),
2663 tp->snd_ssthresh, tp->prior_ssthresh,
2664 tp->packets_out);
2665 }
2666#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
2667 else if (sk->sk_family == AF_INET6) {
2668 struct ipv6_pinfo *np = inet6_sk(sk);
Harvey Harrison5b095d9892008-10-29 12:52:50 -07002669 printk(KERN_DEBUG "Undo %s %pI6/%u c%u l%u ss%u/%u p%u\n",
YOSHIFUJI Hideaki569508c2008-04-14 04:09:36 -07002670 msg,
Joe Perches288fcee2010-05-31 23:48:19 -07002671 &np->daddr, ntohs(inet->inet_dport),
YOSHIFUJI Hideaki569508c2008-04-14 04:09:36 -07002672 tp->snd_cwnd, tcp_left_out(tp),
2673 tp->snd_ssthresh, tp->prior_ssthresh,
2674 tp->packets_out);
2675 }
2676#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002677}
2678#else
2679#define DBGUNDO(x...) do { } while (0)
2680#endif
2681
David S. Millerf6152732011-03-22 19:37:11 -07002682static void tcp_undo_cwr(struct sock *sk, const bool undo_ssthresh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002683{
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002684 struct tcp_sock *tp = tcp_sk(sk);
2685
Linus Torvalds1da177e2005-04-16 15:20:36 -07002686 if (tp->prior_ssthresh) {
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002687 const struct inet_connection_sock *icsk = inet_csk(sk);
2688
2689 if (icsk->icsk_ca_ops->undo_cwnd)
2690 tp->snd_cwnd = icsk->icsk_ca_ops->undo_cwnd(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002691 else
Ilpo Järvinen056834d2007-12-31 14:57:14 -08002692 tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh << 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002693
Yuchung Cheng67d41202011-03-14 10:57:03 +00002694 if (undo_ssthresh && tp->prior_ssthresh > tp->snd_ssthresh) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002695 tp->snd_ssthresh = tp->prior_ssthresh;
2696 TCP_ECN_withdraw_cwr(tp);
2697 }
2698 } else {
2699 tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh);
2700 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002701 tp->snd_cwnd_stamp = tcp_time_stamp;
2702}
2703
Eric Dumazetcf533ea2011-10-21 05:22:42 -04002704static inline int tcp_may_undo(const struct tcp_sock *tp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002705{
Ilpo Järvinen056834d2007-12-31 14:57:14 -08002706 return tp->undo_marker && (!tp->undo_retrans || tcp_packet_delayed(tp));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002707}
2708
2709/* People celebrate: "We love our President!" */
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002710static int tcp_try_undo_recovery(struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002711{
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002712 struct tcp_sock *tp = tcp_sk(sk);
2713
Linus Torvalds1da177e2005-04-16 15:20:36 -07002714 if (tcp_may_undo(tp)) {
Pavel Emelyanov40b215e2008-07-03 01:05:41 -07002715 int mib_idx;
2716
Linus Torvalds1da177e2005-04-16 15:20:36 -07002717 /* Happy end! We did not retransmit anything
2718 * or our original transmission succeeded.
2719 */
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002720 DBGUNDO(sk, inet_csk(sk)->icsk_ca_state == TCP_CA_Loss ? "loss" : "retrans");
David S. Millerf6152732011-03-22 19:37:11 -07002721 tcp_undo_cwr(sk, true);
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002722 if (inet_csk(sk)->icsk_ca_state == TCP_CA_Loss)
Pavel Emelyanov40b215e2008-07-03 01:05:41 -07002723 mib_idx = LINUX_MIB_TCPLOSSUNDO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002724 else
Pavel Emelyanov40b215e2008-07-03 01:05:41 -07002725 mib_idx = LINUX_MIB_TCPFULLUNDO;
2726
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07002727 NET_INC_STATS_BH(sock_net(sk), mib_idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002728 tp->undo_marker = 0;
2729 }
Ilpo Järvinene60402d2007-08-09 15:14:46 +03002730 if (tp->snd_una == tp->high_seq && tcp_is_reno(tp)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002731 /* Hold old state until something *above* high_seq
2732 * is ACKed. For Reno it is MUST to prevent false
2733 * fast retransmits (RFC2582). SACK TCP is safe. */
2734 tcp_moderate_cwnd(tp);
2735 return 1;
2736 }
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002737 tcp_set_ca_state(sk, TCP_CA_Open);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002738 return 0;
2739}
2740
2741/* Try to undo cwnd reduction, because D-SACKs acked all retransmitted data */
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002742static void tcp_try_undo_dsack(struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002743{
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002744 struct tcp_sock *tp = tcp_sk(sk);
2745
Linus Torvalds1da177e2005-04-16 15:20:36 -07002746 if (tp->undo_marker && !tp->undo_retrans) {
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002747 DBGUNDO(sk, "D-SACK");
David S. Millerf6152732011-03-22 19:37:11 -07002748 tcp_undo_cwr(sk, true);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002749 tp->undo_marker = 0;
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07002750 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPDSACKUNDO);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002751 }
2752}
2753
Ilpo Järvinen77722b12009-12-08 20:54:11 -08002754/* We can clear retrans_stamp when there are no retransmissions in the
2755 * window. It would seem that it is trivially available for us in
2756 * tp->retrans_out, however, that kind of assumptions doesn't consider
2757 * what will happen if errors occur when sending retransmission for the
2758 * second time. ...It could the that such segment has only
2759 * TCPCB_EVER_RETRANS set at the present time. It seems that checking
2760 * the head skb is enough except for some reneging corner cases that
2761 * are not worth the effort.
2762 *
2763 * Main reason for all this complexity is the fact that connection dying
2764 * time now depends on the validity of the retrans_stamp, in particular,
2765 * that successive retransmissions of a segment must not advance
2766 * retrans_stamp under any conditions.
2767 */
Eric Dumazetcf533ea2011-10-21 05:22:42 -04002768static int tcp_any_retrans_done(const struct sock *sk)
Ilpo Järvinen77722b12009-12-08 20:54:11 -08002769{
Eric Dumazetcf533ea2011-10-21 05:22:42 -04002770 const struct tcp_sock *tp = tcp_sk(sk);
Ilpo Järvinen77722b12009-12-08 20:54:11 -08002771 struct sk_buff *skb;
2772
2773 if (tp->retrans_out)
2774 return 1;
2775
2776 skb = tcp_write_queue_head(sk);
2777 if (unlikely(skb && TCP_SKB_CB(skb)->sacked & TCPCB_EVER_RETRANS))
2778 return 1;
2779
2780 return 0;
2781}
2782
Linus Torvalds1da177e2005-04-16 15:20:36 -07002783/* Undo during fast recovery after partial ACK. */
2784
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002785static int tcp_try_undo_partial(struct sock *sk, int acked)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002786{
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002787 struct tcp_sock *tp = tcp_sk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002788 /* Partial ACK arrived. Force Hoe's retransmit. */
Ilpo Järvinen85cc3912007-11-15 19:39:31 -08002789 int failed = tcp_is_reno(tp) || (tcp_fackets_out(tp) > tp->reordering);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002790
2791 if (tcp_may_undo(tp)) {
2792 /* Plain luck! Hole if filled with delayed
2793 * packet, rather than with a retransmit.
2794 */
Ilpo Järvinen77722b12009-12-08 20:54:11 -08002795 if (!tcp_any_retrans_done(sk))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002796 tp->retrans_stamp = 0;
2797
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002798 tcp_update_reordering(sk, tcp_fackets_out(tp) + acked, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002799
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002800 DBGUNDO(sk, "Hoe");
David S. Millerf6152732011-03-22 19:37:11 -07002801 tcp_undo_cwr(sk, false);
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07002802 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPPARTIALUNDO);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002803
2804 /* So... Do not make Hoe's retransmit yet.
2805 * If the first packet was delayed, the rest
2806 * ones are most probably delayed as well.
2807 */
2808 failed = 0;
2809 }
2810 return failed;
2811}
2812
2813/* Undo during loss recovery after partial ACK. */
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002814static int tcp_try_undo_loss(struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002815{
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002816 struct tcp_sock *tp = tcp_sk(sk);
2817
Linus Torvalds1da177e2005-04-16 15:20:36 -07002818 if (tcp_may_undo(tp)) {
2819 struct sk_buff *skb;
David S. Millerfe067e82007-03-07 12:12:44 -08002820 tcp_for_write_queue(skb, sk) {
2821 if (skb == tcp_send_head(sk))
2822 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002823 TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
2824 }
Stephen Hemminger6a438bb2005-11-10 17:14:59 -08002825
Ilpo Järvinen5af4ec22007-09-20 11:30:48 -07002826 tcp_clear_all_retrans_hints(tp);
Stephen Hemminger6a438bb2005-11-10 17:14:59 -08002827
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002828 DBGUNDO(sk, "partial loss");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002829 tp->lost_out = 0;
David S. Millerf6152732011-03-22 19:37:11 -07002830 tcp_undo_cwr(sk, true);
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07002831 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSSUNDO);
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07002832 inet_csk(sk)->icsk_retransmits = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002833 tp->undo_marker = 0;
Ilpo Järvinene60402d2007-08-09 15:14:46 +03002834 if (tcp_is_sack(tp))
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002835 tcp_set_ca_state(sk, TCP_CA_Open);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002836 return 1;
2837 }
2838 return 0;
2839}
2840
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002841static inline void tcp_complete_cwr(struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002842{
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002843 struct tcp_sock *tp = tcp_sk(sk);
Nandita Dukkipatia262f0c2011-08-21 20:21:57 +00002844
2845 /* Do not moderate cwnd if it's already undone in cwr or recovery. */
2846 if (tp->undo_marker) {
2847 if (inet_csk(sk)->icsk_ca_state == TCP_CA_CWR)
2848 tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);
2849 else /* PRR */
2850 tp->snd_cwnd = tp->snd_ssthresh;
Yuchung Cheng67d41202011-03-14 10:57:03 +00002851 tp->snd_cwnd_stamp = tcp_time_stamp;
2852 }
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002853 tcp_ca_event(sk, CA_EVENT_COMPLETE_CWR);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002854}
2855
Ilpo Järvinen8aca6cb2008-06-04 11:34:22 -07002856static void tcp_try_keep_open(struct sock *sk)
2857{
2858 struct tcp_sock *tp = tcp_sk(sk);
2859 int state = TCP_CA_Open;
2860
Ilpo Järvinen77722b12009-12-08 20:54:11 -08002861 if (tcp_left_out(tp) || tcp_any_retrans_done(sk) || tp->undo_marker)
Ilpo Järvinen8aca6cb2008-06-04 11:34:22 -07002862 state = TCP_CA_Disorder;
2863
2864 if (inet_csk(sk)->icsk_ca_state != state) {
2865 tcp_set_ca_state(sk, state);
2866 tp->high_seq = tp->snd_nxt;
2867 }
2868}
2869
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002870static void tcp_try_to_open(struct sock *sk, int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002871{
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07002872 struct tcp_sock *tp = tcp_sk(sk);
2873
Ilpo Järvinen86426c22007-08-09 14:45:17 +03002874 tcp_verify_left_out(tp);
2875
Ilpo Järvinen77722b12009-12-08 20:54:11 -08002876 if (!tp->frto_counter && !tcp_any_retrans_done(sk))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002877 tp->retrans_stamp = 0;
2878
Ilpo Järvinen056834d2007-12-31 14:57:14 -08002879 if (flag & FLAG_ECE)
Ilpo Järvinen3cfe3ba2007-02-27 10:09:49 -08002880 tcp_enter_cwr(sk, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002881
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03002882 if (inet_csk(sk)->icsk_ca_state != TCP_CA_CWR) {
Ilpo Järvinen8aca6cb2008-06-04 11:34:22 -07002883 tcp_try_keep_open(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002884 tcp_moderate_cwnd(tp);
2885 } else {
Ilpo Järvinen1e757f92007-07-30 19:48:37 -07002886 tcp_cwnd_down(sk, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002887 }
2888}
2889
John Heffner5d424d52006-03-20 17:53:41 -08002890static void tcp_mtup_probe_failed(struct sock *sk)
2891{
2892 struct inet_connection_sock *icsk = inet_csk(sk);
2893
2894 icsk->icsk_mtup.search_high = icsk->icsk_mtup.probe_size - 1;
2895 icsk->icsk_mtup.probe_size = 0;
2896}
2897
Ilpo Järvinen72211e92009-03-14 14:23:04 +00002898static void tcp_mtup_probe_success(struct sock *sk)
John Heffner5d424d52006-03-20 17:53:41 -08002899{
2900 struct tcp_sock *tp = tcp_sk(sk);
2901 struct inet_connection_sock *icsk = inet_csk(sk);
2902
2903 /* FIXME: breaks with very large cwnd */
2904 tp->prior_ssthresh = tcp_current_ssthresh(sk);
2905 tp->snd_cwnd = tp->snd_cwnd *
2906 tcp_mss_to_mtu(sk, tp->mss_cache) /
2907 icsk->icsk_mtup.probe_size;
2908 tp->snd_cwnd_cnt = 0;
2909 tp->snd_cwnd_stamp = tcp_time_stamp;
John Heffner9c6d5e52010-10-06 21:18:02 -07002910 tp->snd_ssthresh = tcp_current_ssthresh(sk);
John Heffner5d424d52006-03-20 17:53:41 -08002911
2912 icsk->icsk_mtup.search_low = icsk->icsk_mtup.probe_size;
2913 icsk->icsk_mtup.probe_size = 0;
2914 tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
2915}
2916
Ilpo Järvinene1aa6802008-11-24 21:11:55 -08002917/* Do a simple retransmit without using the backoff mechanisms in
2918 * tcp_timer. This is used for path mtu discovery.
2919 * The socket is already locked here.
2920 */
2921void tcp_simple_retransmit(struct sock *sk)
2922{
2923 const struct inet_connection_sock *icsk = inet_csk(sk);
2924 struct tcp_sock *tp = tcp_sk(sk);
2925 struct sk_buff *skb;
Ilpo Järvinen0c54b852009-03-14 14:23:05 +00002926 unsigned int mss = tcp_current_mss(sk);
Ilpo Järvinene1aa6802008-11-24 21:11:55 -08002927 u32 prior_lost = tp->lost_out;
2928
2929 tcp_for_write_queue(skb, sk) {
2930 if (skb == tcp_send_head(sk))
2931 break;
Ilpo Järvinen775ffab2008-12-05 22:41:26 -08002932 if (tcp_skb_seglen(skb) > mss &&
Ilpo Järvinene1aa6802008-11-24 21:11:55 -08002933 !(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) {
2934 if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) {
2935 TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
2936 tp->retrans_out -= tcp_skb_pcount(skb);
2937 }
2938 tcp_skb_mark_lost_uncond_verify(tp, skb);
2939 }
2940 }
2941
2942 tcp_clear_retrans_hints_partial(tp);
2943
2944 if (prior_lost == tp->lost_out)
2945 return;
2946
2947 if (tcp_is_reno(tp))
2948 tcp_limit_reno_sacked(tp);
2949
2950 tcp_verify_left_out(tp);
2951
2952 /* Don't muck with the congestion window here.
2953 * Reason is that we do not increase amount of _data_
2954 * in network, but units changed and effective
2955 * cwnd/ssthresh really reduced now.
2956 */
2957 if (icsk->icsk_ca_state != TCP_CA_Loss) {
2958 tp->high_seq = tp->snd_nxt;
2959 tp->snd_ssthresh = tcp_current_ssthresh(sk);
2960 tp->prior_ssthresh = 0;
2961 tp->undo_marker = 0;
2962 tcp_set_ca_state(sk, TCP_CA_Loss);
2963 }
2964 tcp_xmit_retransmit_queue(sk);
2965}
Eric Dumazet4bc2f182010-07-09 21:22:10 +00002966EXPORT_SYMBOL(tcp_simple_retransmit);
Ilpo Järvinene1aa6802008-11-24 21:11:55 -08002967
Nandita Dukkipatia262f0c2011-08-21 20:21:57 +00002968/* This function implements the PRR algorithm, specifcally the PRR-SSRB
2969 * (proportional rate reduction with slow start reduction bound) as described in
2970 * http://www.ietf.org/id/draft-mathis-tcpm-proportional-rate-reduction-01.txt.
2971 * It computes the number of packets to send (sndcnt) based on packets newly
2972 * delivered:
2973 * 1) If the packets in flight is larger than ssthresh, PRR spreads the
2974 * cwnd reductions across a full RTT.
2975 * 2) If packets in flight is lower than ssthresh (such as due to excess
2976 * losses and/or application stalls), do not perform any further cwnd
2977 * reductions, but instead slow start up to ssthresh.
2978 */
2979static void tcp_update_cwnd_in_recovery(struct sock *sk, int newly_acked_sacked,
2980 int fast_rexmit, int flag)
2981{
2982 struct tcp_sock *tp = tcp_sk(sk);
2983 int sndcnt = 0;
2984 int delta = tp->snd_ssthresh - tcp_packets_in_flight(tp);
2985
2986 if (tcp_packets_in_flight(tp) > tp->snd_ssthresh) {
2987 u64 dividend = (u64)tp->snd_ssthresh * tp->prr_delivered +
2988 tp->prior_cwnd - 1;
2989 sndcnt = div_u64(dividend, tp->prior_cwnd) - tp->prr_out;
2990 } else {
2991 sndcnt = min_t(int, delta,
2992 max_t(int, tp->prr_delivered - tp->prr_out,
2993 newly_acked_sacked) + 1);
2994 }
2995
2996 sndcnt = max(sndcnt, (fast_rexmit ? 1 : 0));
2997 tp->snd_cwnd = tcp_packets_in_flight(tp) + sndcnt;
2998}
2999
Linus Torvalds1da177e2005-04-16 15:20:36 -07003000/* Process an event, which can update packets-in-flight not trivially.
3001 * Main goal of this function is to calculate new estimate for left_out,
3002 * taking into account both packets sitting in receiver's buffer and
3003 * packets lost by network.
3004 *
3005 * Besides that it does CWND reduction, when packet loss is detected
3006 * and changes state of machine.
3007 *
3008 * It does _not_ decide what to send, it is made in function
3009 * tcp_xmit_retransmit_queue().
3010 */
Nandita Dukkipatia262f0c2011-08-21 20:21:57 +00003011static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
3012 int newly_acked_sacked, int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003013{
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003014 struct inet_connection_sock *icsk = inet_csk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003015 struct tcp_sock *tp = tcp_sk(sk);
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003016 int is_dupack = !(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP));
3017 int do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&
Ilpo Järvinen85cc3912007-11-15 19:39:31 -08003018 (tcp_fackets_out(tp) > tp->reordering));
Pavel Emelyanov40b215e2008-07-03 01:05:41 -07003019 int fast_rexmit = 0, mib_idx;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003020
Ilpo Järvinen3ccd3132007-12-31 04:43:32 -08003021 if (WARN_ON(!tp->packets_out && tp->sacked_out))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003022 tp->sacked_out = 0;
Ilpo Järvinen91fed7a2007-10-09 01:24:15 -07003023 if (WARN_ON(!tp->sacked_out && tp->fackets_out))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003024 tp->fackets_out = 0;
3025
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09003026 /* Now state machine starts.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003027 * A. ECE, hence prohibit cwnd undoing, the reduction is required. */
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003028 if (flag & FLAG_ECE)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003029 tp->prior_ssthresh = 0;
3030
3031 /* B. In all the states check for reneging SACKs. */
Ilpo Järvinencadbd032007-12-31 04:49:21 -08003032 if (tcp_check_sack_reneging(sk, flag))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003033 return;
3034
3035 /* C. Process data loss notification, provided it is valid. */
Ilpo Järvinen85cc3912007-11-15 19:39:31 -08003036 if (tcp_is_fack(tp) && (flag & FLAG_DATA_LOST) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07003037 before(tp->snd_una, tp->high_seq) &&
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003038 icsk->icsk_ca_state != TCP_CA_Open &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07003039 tp->fackets_out > tp->reordering) {
Ilpo Järvinen1fdb9362010-10-14 01:42:30 +00003040 tcp_mark_head_lost(sk, tp->fackets_out - tp->reordering, 0);
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07003041 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003042 }
3043
Ilpo Järvinen005903b2007-08-09 14:44:16 +03003044 /* D. Check consistency of the current state. */
3045 tcp_verify_left_out(tp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003046
3047 /* E. Check state exit conditions. State can be terminated
3048 * when high_seq is ACKed. */
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003049 if (icsk->icsk_ca_state == TCP_CA_Open) {
Ilpo Järvinen547b7922008-07-25 21:43:18 -07003050 WARN_ON(tp->retrans_out != 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003051 tp->retrans_stamp = 0;
3052 } else if (!before(tp->snd_una, tp->high_seq)) {
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003053 switch (icsk->icsk_ca_state) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003054 case TCP_CA_Loss:
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003055 icsk->icsk_retransmits = 0;
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07003056 if (tcp_try_undo_recovery(sk))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003057 return;
3058 break;
3059
3060 case TCP_CA_CWR:
3061 /* CWR is to be held something *above* high_seq
3062 * is ACKed for CWR bit to reach receiver. */
3063 if (tp->snd_una != tp->high_seq) {
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003064 tcp_complete_cwr(sk);
3065 tcp_set_ca_state(sk, TCP_CA_Open);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003066 }
3067 break;
3068
3069 case TCP_CA_Disorder:
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07003070 tcp_try_undo_dsack(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003071 if (!tp->undo_marker ||
3072 /* For SACK case do not Open to allow to undo
3073 * catching for all duplicate ACKs. */
Ilpo Järvinene60402d2007-08-09 15:14:46 +03003074 tcp_is_reno(tp) || tp->snd_una != tp->high_seq) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003075 tp->undo_marker = 0;
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003076 tcp_set_ca_state(sk, TCP_CA_Open);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003077 }
3078 break;
3079
3080 case TCP_CA_Recovery:
Ilpo Järvinene60402d2007-08-09 15:14:46 +03003081 if (tcp_is_reno(tp))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003082 tcp_reset_reno_sack(tp);
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07003083 if (tcp_try_undo_recovery(sk))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003084 return;
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003085 tcp_complete_cwr(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003086 break;
3087 }
3088 }
3089
3090 /* F. Process state. */
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003091 switch (icsk->icsk_ca_state) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003092 case TCP_CA_Recovery:
Ilpo Järvinen2e605292007-08-02 19:46:58 -07003093 if (!(flag & FLAG_SND_UNA_ADVANCED)) {
Ilpo Järvinene60402d2007-08-09 15:14:46 +03003094 if (tcp_is_reno(tp) && is_dupack)
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003095 tcp_add_reno_sack(sk);
Ilpo Järvinen1b6d427b2007-08-09 14:53:36 +03003096 } else
3097 do_lost = tcp_try_undo_partial(sk, pkts_acked);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003098 break;
3099 case TCP_CA_Loss:
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003100 if (flag & FLAG_DATA_ACKED)
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003101 icsk->icsk_retransmits = 0;
Ilpo Järvinen882beba2008-04-07 22:33:07 -07003102 if (tcp_is_reno(tp) && flag & FLAG_SND_UNA_ADVANCED)
3103 tcp_reset_reno_sack(tp);
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07003104 if (!tcp_try_undo_loss(sk)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003105 tcp_moderate_cwnd(tp);
3106 tcp_xmit_retransmit_queue(sk);
3107 return;
3108 }
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003109 if (icsk->icsk_ca_state != TCP_CA_Open)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003110 return;
3111 /* Loss is undone; fall through to processing in Open state. */
3112 default:
Ilpo Järvinene60402d2007-08-09 15:14:46 +03003113 if (tcp_is_reno(tp)) {
Ilpo Järvinen2e605292007-08-02 19:46:58 -07003114 if (flag & FLAG_SND_UNA_ADVANCED)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003115 tcp_reset_reno_sack(tp);
3116 if (is_dupack)
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003117 tcp_add_reno_sack(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003118 }
3119
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003120 if (icsk->icsk_ca_state == TCP_CA_Disorder)
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07003121 tcp_try_undo_dsack(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003122
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07003123 if (!tcp_time_to_recover(sk)) {
3124 tcp_try_to_open(sk, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003125 return;
3126 }
3127
John Heffner5d424d52006-03-20 17:53:41 -08003128 /* MTU probe failure: don't reduce cwnd */
3129 if (icsk->icsk_ca_state < TCP_CA_CWR &&
3130 icsk->icsk_mtup.probe_size &&
John Heffner0e7b1362006-03-20 21:32:58 -08003131 tp->snd_una == tp->mtu_probe.probe_seq_start) {
John Heffner5d424d52006-03-20 17:53:41 -08003132 tcp_mtup_probe_failed(sk);
3133 /* Restores the reduction we did in tcp_mtup_probe() */
3134 tp->snd_cwnd++;
3135 tcp_simple_retransmit(sk);
3136 return;
3137 }
3138
Linus Torvalds1da177e2005-04-16 15:20:36 -07003139 /* Otherwise enter Recovery state */
3140
Ilpo Järvinene60402d2007-08-09 15:14:46 +03003141 if (tcp_is_reno(tp))
Pavel Emelyanov40b215e2008-07-03 01:05:41 -07003142 mib_idx = LINUX_MIB_TCPRENORECOVERY;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003143 else
Pavel Emelyanov40b215e2008-07-03 01:05:41 -07003144 mib_idx = LINUX_MIB_TCPSACKRECOVERY;
3145
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07003146 NET_INC_STATS_BH(sock_net(sk), mib_idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003147
3148 tp->high_seq = tp->snd_nxt;
3149 tp->prior_ssthresh = 0;
3150 tp->undo_marker = tp->snd_una;
3151 tp->undo_retrans = tp->retrans_out;
3152
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003153 if (icsk->icsk_ca_state < TCP_CA_CWR) {
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003154 if (!(flag & FLAG_ECE))
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003155 tp->prior_ssthresh = tcp_current_ssthresh(sk);
3156 tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003157 TCP_ECN_queue_cwr(tp);
3158 }
3159
Stephen Hemminger9772efb2005-11-10 17:09:53 -08003160 tp->bytes_acked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003161 tp->snd_cwnd_cnt = 0;
Nandita Dukkipatia262f0c2011-08-21 20:21:57 +00003162 tp->prior_cwnd = tp->snd_cwnd;
3163 tp->prr_delivered = 0;
3164 tp->prr_out = 0;
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003165 tcp_set_ca_state(sk, TCP_CA_Recovery);
Ilpo Järvinen85cc3912007-11-15 19:39:31 -08003166 fast_rexmit = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003167 }
3168
Ilpo Järvinen85cc3912007-11-15 19:39:31 -08003169 if (do_lost || (tcp_is_fack(tp) && tcp_head_timedout(sk)))
3170 tcp_update_scoreboard(sk, fast_rexmit);
Nandita Dukkipatia262f0c2011-08-21 20:21:57 +00003171 tp->prr_delivered += newly_acked_sacked;
3172 tcp_update_cwnd_in_recovery(sk, newly_acked_sacked, fast_rexmit, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003173 tcp_xmit_retransmit_queue(sk);
3174}
3175
Jerry Chu9ad7c042011-06-08 11:08:38 +00003176void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt)
Ilpo Järvinen41834b72008-12-05 22:43:26 -08003177{
3178 tcp_rtt_estimator(sk, seq_rtt);
3179 tcp_set_rto(sk);
3180 inet_csk(sk)->icsk_backoff = 0;
3181}
Jerry Chu9ad7c042011-06-08 11:08:38 +00003182EXPORT_SYMBOL(tcp_valid_rtt_meas);
Ilpo Järvinen41834b72008-12-05 22:43:26 -08003183
Linus Torvalds1da177e2005-04-16 15:20:36 -07003184/* Read draft-ietf-tcplw-high-performance before mucking
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -08003185 * with this code. (Supersedes RFC1323)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003186 */
Stephen Hemminger2d2abba2005-11-10 16:56:12 -08003187static void tcp_ack_saw_tstamp(struct sock *sk, int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003188{
Linus Torvalds1da177e2005-04-16 15:20:36 -07003189 /* RTTM Rule: A TSecr value received in a segment is used to
3190 * update the averaged RTT measurement only if the segment
3191 * acknowledges some new data, i.e., only if it advances the
3192 * left edge of the send window.
3193 *
3194 * See draft-ietf-tcplw-high-performance-00, section 3.3.
3195 * 1998/04/10 Andrey V. Savochkin <saw@msu.ru>
3196 *
3197 * Changed: reset backoff as soon as we see the first valid sample.
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -08003198 * If we do not, we get strongly overestimated rto. With timestamps
Linus Torvalds1da177e2005-04-16 15:20:36 -07003199 * samples are accepted even from very old segments: f.e., when rtt=1
3200 * increases to 8, we retransmit 5 times and after 8 seconds delayed
3201 * answer arrives rto becomes 120 seconds! If at least one of segments
3202 * in window is lost... Voila. --ANK (010210)
3203 */
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07003204 struct tcp_sock *tp = tcp_sk(sk);
Ilpo Järvinen41834b72008-12-05 22:43:26 -08003205
3206 tcp_valid_rtt_meas(sk, tcp_time_stamp - tp->rx_opt.rcv_tsecr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003207}
3208
Stephen Hemminger2d2abba2005-11-10 16:56:12 -08003209static void tcp_ack_no_tstamp(struct sock *sk, u32 seq_rtt, int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003210{
3211 /* We don't have a timestamp. Can only use
3212 * packets that are not retransmitted to determine
3213 * rtt estimates. Also, we must not reset the
3214 * backoff for rto until we get a non-retransmitted
3215 * packet. This allows us to deal with a situation
3216 * where the network delay has increased suddenly.
3217 * I.e. Karn's algorithm. (SIGCOMM '87, p5.)
3218 */
3219
3220 if (flag & FLAG_RETRANS_DATA_ACKED)
3221 return;
3222
Ilpo Järvinen41834b72008-12-05 22:43:26 -08003223 tcp_valid_rtt_meas(sk, seq_rtt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003224}
3225
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07003226static inline void tcp_ack_update_rtt(struct sock *sk, const int flag,
Stephen Hemminger2d2abba2005-11-10 16:56:12 -08003227 const s32 seq_rtt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003228{
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07003229 const struct tcp_sock *tp = tcp_sk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003230 /* Note that peer MAY send zero echo. In this case it is ignored. (rfc1323) */
3231 if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr)
Stephen Hemminger2d2abba2005-11-10 16:56:12 -08003232 tcp_ack_saw_tstamp(sk, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003233 else if (seq_rtt >= 0)
Stephen Hemminger2d2abba2005-11-10 16:56:12 -08003234 tcp_ack_no_tstamp(sk, seq_rtt, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003235}
3236
Ilpo Järvinenc3a05c62007-12-02 00:47:59 +02003237static void tcp_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003238{
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003239 const struct inet_connection_sock *icsk = inet_csk(sk);
Ilpo Järvinenc3a05c62007-12-02 00:47:59 +02003240 icsk->icsk_ca_ops->cong_avoid(sk, ack, in_flight);
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003241 tcp_sk(sk)->snd_cwnd_stamp = tcp_time_stamp;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003242}
3243
Linus Torvalds1da177e2005-04-16 15:20:36 -07003244/* Restart timer after forward progress on connection.
3245 * RFC2988 recommends to restart timer to now+rto.
3246 */
Ilpo Järvinen6728e7d2007-08-24 22:53:26 -07003247static void tcp_rearm_rto(struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003248{
Eric Dumazetcf533ea2011-10-21 05:22:42 -04003249 const struct tcp_sock *tp = tcp_sk(sk);
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07003250
Linus Torvalds1da177e2005-04-16 15:20:36 -07003251 if (!tp->packets_out) {
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07003252 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003253 } else {
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003254 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
3255 inet_csk(sk)->icsk_rto, TCP_RTO_MAX);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003256 }
3257}
3258
Ilpo Järvinen7c46a032007-09-20 11:33:43 -07003259/* If we get here, the whole TSO packet has not been acked. */
Ilpo Järvinen13fcf852007-10-09 01:28:45 -07003260static u32 tcp_tso_acked(struct sock *sk, struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003261{
3262 struct tcp_sock *tp = tcp_sk(sk);
Ilpo Järvinen7c46a032007-09-20 11:33:43 -07003263 u32 packets_acked;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003264
Ilpo Järvinen7c46a032007-09-20 11:33:43 -07003265 BUG_ON(!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una));
Linus Torvalds1da177e2005-04-16 15:20:36 -07003266
3267 packets_acked = tcp_skb_pcount(skb);
Ilpo Järvinen7c46a032007-09-20 11:33:43 -07003268 if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003269 return 0;
3270 packets_acked -= tcp_skb_pcount(skb);
3271
3272 if (packets_acked) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003273 BUG_ON(tcp_skb_pcount(skb) == 0);
Ilpo Järvinen7c46a032007-09-20 11:33:43 -07003274 BUG_ON(!before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07003275 }
3276
Ilpo Järvinen13fcf852007-10-09 01:28:45 -07003277 return packets_acked;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003278}
3279
Ilpo Järvinen7c46a032007-09-20 11:33:43 -07003280/* Remove acknowledged frames from the retransmission queue. If our packet
3281 * is before the ack sequence we can discard it as it's confirmed to have
3282 * arrived at the other end.
3283 */
Ilpo Järvinen33f5f572008-10-07 14:43:06 -07003284static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
3285 u32 prior_snd_una)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003286{
3287 struct tcp_sock *tp = tcp_sk(sk);
Stephen Hemminger2d2abba2005-11-10 16:56:12 -08003288 const struct inet_connection_sock *icsk = inet_csk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003289 struct sk_buff *skb;
Ilpo Järvinen7c46a032007-09-20 11:33:43 -07003290 u32 now = tcp_time_stamp;
Ilpo Järvinen13fcf852007-10-09 01:28:45 -07003291 int fully_acked = 1;
Ilpo Järvinen7c46a032007-09-20 11:33:43 -07003292 int flag = 0;
Ilpo Järvinen72018832007-12-30 04:37:55 -08003293 u32 pkts_acked = 0;
Ilpo Järvinenc7caf8d2007-11-10 21:22:18 -08003294 u32 reord = tp->packets_out;
Ilpo Järvinen90638a02008-09-20 21:25:52 -07003295 u32 prior_sacked = tp->sacked_out;
Ilpo Järvinen7c46a032007-09-20 11:33:43 -07003296 s32 seq_rtt = -1;
Gavin McCullagh2072c222007-12-29 19:11:21 -08003297 s32 ca_seq_rtt = -1;
Ilpo Järvinenb9ce2042007-06-15 15:08:43 -07003298 ktime_t last_ackt = net_invalid_timestamp();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003299
Ilpo Järvinen7c46a032007-09-20 11:33:43 -07003300 while ((skb = tcp_write_queue_head(sk)) && skb != tcp_send_head(sk)) {
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09003301 struct tcp_skb_cb *scb = TCP_SKB_CB(skb);
Ilpo Järvinen72018832007-12-30 04:37:55 -08003302 u32 acked_pcount;
Ilpo Järvinen7c46a032007-09-20 11:33:43 -07003303 u8 sacked = scb->sacked;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003304
Gavin McCullagh2072c222007-12-29 19:11:21 -08003305 /* Determine how many packets and what bytes were acked, tso and else */
Linus Torvalds1da177e2005-04-16 15:20:36 -07003306 if (after(scb->end_seq, tp->snd_una)) {
Ilpo Järvinen13fcf852007-10-09 01:28:45 -07003307 if (tcp_skb_pcount(skb) == 1 ||
3308 !after(tp->snd_una, scb->seq))
3309 break;
3310
Ilpo Järvinen72018832007-12-30 04:37:55 -08003311 acked_pcount = tcp_tso_acked(sk, skb);
3312 if (!acked_pcount)
Ilpo Järvinen13fcf852007-10-09 01:28:45 -07003313 break;
3314
3315 fully_acked = 0;
Ilpo Järvinen13fcf852007-10-09 01:28:45 -07003316 } else {
Ilpo Järvinen72018832007-12-30 04:37:55 -08003317 acked_pcount = tcp_skb_pcount(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003318 }
3319
Ilpo Järvinen89d478f2007-12-30 04:35:27 -08003320 if (sacked & TCPCB_RETRANS) {
3321 if (sacked & TCPCB_SACKED_RETRANS)
Ilpo Järvinen72018832007-12-30 04:37:55 -08003322 tp->retrans_out -= acked_pcount;
Ilpo Järvinen89d478f2007-12-30 04:35:27 -08003323 flag |= FLAG_RETRANS_DATA_ACKED;
3324 ca_seq_rtt = -1;
3325 seq_rtt = -1;
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003326 if ((flag & FLAG_DATA_ACKED) || (acked_pcount > 1))
Ilpo Järvinen89d478f2007-12-30 04:35:27 -08003327 flag |= FLAG_NONHEAD_RETRANS_ACKED;
Ilpo Järvinenc7caf8d2007-11-10 21:22:18 -08003328 } else {
Gavin McCullagh2072c222007-12-29 19:11:21 -08003329 ca_seq_rtt = now - scb->when;
3330 last_ackt = skb->tstamp;
Ilpo Järvinenc7caf8d2007-11-10 21:22:18 -08003331 if (seq_rtt < 0) {
Gavin McCullagh2072c222007-12-29 19:11:21 -08003332 seq_rtt = ca_seq_rtt;
Ilpo Järvinenc7caf8d2007-11-10 21:22:18 -08003333 }
Ilpo Järvinen89d478f2007-12-30 04:35:27 -08003334 if (!(sacked & TCPCB_SACKED_ACKED))
Ilpo Järvinen72018832007-12-30 04:37:55 -08003335 reord = min(pkts_acked, reord);
Stephen Hemminger2d2abba2005-11-10 16:56:12 -08003336 }
Ilpo Järvinen89d478f2007-12-30 04:35:27 -08003337
3338 if (sacked & TCPCB_SACKED_ACKED)
Ilpo Järvinen72018832007-12-30 04:37:55 -08003339 tp->sacked_out -= acked_pcount;
Ilpo Järvinen89d478f2007-12-30 04:35:27 -08003340 if (sacked & TCPCB_LOST)
Ilpo Järvinen72018832007-12-30 04:37:55 -08003341 tp->lost_out -= acked_pcount;
Ilpo Järvinen89d478f2007-12-30 04:35:27 -08003342
Ilpo Järvinen72018832007-12-30 04:37:55 -08003343 tp->packets_out -= acked_pcount;
3344 pkts_acked += acked_pcount;
Ilpo Järvinen13fcf852007-10-09 01:28:45 -07003345
Ilpo Järvinen009a2e32007-09-20 11:34:38 -07003346 /* Initial outgoing SYN's get put onto the write_queue
3347 * just like anything else we transmit. It is not
3348 * true data, and if we misinform our callers that
3349 * this ACK acks real data, we will erroneously exit
3350 * connection startup slow start one packet too
3351 * quickly. This is severely frowned upon behavior.
3352 */
Eric Dumazet4de075e2011-09-27 13:25:05 -04003353 if (!(scb->tcp_flags & TCPHDR_SYN)) {
Ilpo Järvinen009a2e32007-09-20 11:34:38 -07003354 flag |= FLAG_DATA_ACKED;
3355 } else {
3356 flag |= FLAG_SYN_ACKED;
3357 tp->retrans_stamp = 0;
3358 }
3359
Ilpo Järvinen13fcf852007-10-09 01:28:45 -07003360 if (!fully_acked)
3361 break;
3362
David S. Millerfe067e82007-03-07 12:12:44 -08003363 tcp_unlink_write_queue(skb, sk);
Hideo Aoki3ab224b2007-12-31 00:11:19 -08003364 sk_wmem_free_skb(sk, skb);
Ilpo Järvinen90638a02008-09-20 21:25:52 -07003365 tp->scoreboard_skb_hint = NULL;
Ilpo Järvinenef9da472008-09-20 21:25:15 -07003366 if (skb == tp->retransmit_skb_hint)
3367 tp->retransmit_skb_hint = NULL;
Ilpo Järvinen90638a02008-09-20 21:25:52 -07003368 if (skb == tp->lost_skb_hint)
3369 tp->lost_skb_hint = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003370 }
3371
Ilpo Järvinen33f5f572008-10-07 14:43:06 -07003372 if (likely(between(tp->snd_up, prior_snd_una, tp->snd_una)))
3373 tp->snd_up = tp->snd_una;
3374
Ilpo Järvinencadbd032007-12-31 04:49:21 -08003375 if (skb && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))
3376 flag |= FLAG_SACK_RENEGING;
3377
Ilpo Järvinen7c46a032007-09-20 11:33:43 -07003378 if (flag & FLAG_ACKED) {
Stephen Hemminger164891a2007-04-23 22:26:16 -07003379 const struct tcp_congestion_ops *ca_ops
3380 = inet_csk(sk)->icsk_ca_ops;
3381
Ilpo Järvinen72211e92009-03-14 14:23:04 +00003382 if (unlikely(icsk->icsk_mtup.probe_size &&
3383 !after(tp->mtu_probe.probe_seq_end, tp->snd_una))) {
3384 tcp_mtup_probe_success(sk);
3385 }
3386
Ilpo Järvinen7c46a032007-09-20 11:33:43 -07003387 tcp_ack_update_rtt(sk, flag, seq_rtt);
Ilpo Järvinen6728e7d2007-08-24 22:53:26 -07003388 tcp_rearm_rto(sk);
Stephen Hemminger317a76f2005-06-23 12:19:55 -07003389
Ilpo Järvinenc7caf8d2007-11-10 21:22:18 -08003390 if (tcp_is_reno(tp)) {
3391 tcp_remove_reno_sacks(sk, pkts_acked);
3392 } else {
Ilpo Järvinen59a08cb2009-02-28 04:44:28 +00003393 int delta;
3394
Ilpo Järvinenc7caf8d2007-11-10 21:22:18 -08003395 /* Non-retransmitted hole got filled? That's reordering */
3396 if (reord < prior_fackets)
3397 tcp_update_reordering(sk, tp->fackets_out - reord, 0);
Ilpo Järvinen90638a02008-09-20 21:25:52 -07003398
Ilpo Järvinen59a08cb2009-02-28 04:44:28 +00003399 delta = tcp_is_fack(tp) ? pkts_acked :
3400 prior_sacked - tp->sacked_out;
3401 tp->lost_cnt_hint -= min(tp->lost_cnt_hint, delta);
Ilpo Järvinenc7caf8d2007-11-10 21:22:18 -08003402 }
3403
Ilpo Järvinen91fed7a2007-10-09 01:24:15 -07003404 tp->fackets_out -= min(pkts_acked, tp->fackets_out);
Ilpo Järvinen68f83532007-11-15 19:50:37 -08003405
Stephen Hemminger30cfd0b2007-07-25 23:49:34 -07003406 if (ca_ops->pkts_acked) {
3407 s32 rtt_us = -1;
Ilpo Järvinenb9ce2042007-06-15 15:08:43 -07003408
Stephen Hemminger30cfd0b2007-07-25 23:49:34 -07003409 /* Is the ACK triggering packet unambiguous? */
Ilpo Järvinen7c46a032007-09-20 11:33:43 -07003410 if (!(flag & FLAG_RETRANS_DATA_ACKED)) {
Stephen Hemminger30cfd0b2007-07-25 23:49:34 -07003411 /* High resolution needed and available? */
3412 if (ca_ops->flags & TCP_CONG_RTT_STAMP &&
3413 !ktime_equal(last_ackt,
3414 net_invalid_timestamp()))
3415 rtt_us = ktime_us_delta(ktime_get_real(),
3416 last_ackt);
stephen hemmingerfebf0812011-03-14 07:52:12 +00003417 else if (ca_seq_rtt >= 0)
Gavin McCullagh2072c222007-12-29 19:11:21 -08003418 rtt_us = jiffies_to_usecs(ca_seq_rtt);
Stephen Hemminger30cfd0b2007-07-25 23:49:34 -07003419 }
3420
3421 ca_ops->pkts_acked(sk, pkts_acked, rtt_us);
3422 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07003423 }
3424
3425#if FASTRETRANS_DEBUG > 0
Ilpo Järvinen547b7922008-07-25 21:43:18 -07003426 WARN_ON((int)tp->sacked_out < 0);
3427 WARN_ON((int)tp->lost_out < 0);
3428 WARN_ON((int)tp->retrans_out < 0);
Ilpo Järvinene60402d2007-08-09 15:14:46 +03003429 if (!tp->packets_out && tcp_is_sack(tp)) {
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -07003430 icsk = inet_csk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003431 if (tp->lost_out) {
3432 printk(KERN_DEBUG "Leak l=%u %d\n",
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003433 tp->lost_out, icsk->icsk_ca_state);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003434 tp->lost_out = 0;
3435 }
3436 if (tp->sacked_out) {
3437 printk(KERN_DEBUG "Leak s=%u %d\n",
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003438 tp->sacked_out, icsk->icsk_ca_state);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003439 tp->sacked_out = 0;
3440 }
3441 if (tp->retrans_out) {
3442 printk(KERN_DEBUG "Leak r=%u %d\n",
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003443 tp->retrans_out, icsk->icsk_ca_state);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003444 tp->retrans_out = 0;
3445 }
3446 }
3447#endif
Ilpo Järvinen7c46a032007-09-20 11:33:43 -07003448 return flag;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003449}
3450
3451static void tcp_ack_probe(struct sock *sk)
3452{
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07003453 const struct tcp_sock *tp = tcp_sk(sk);
3454 struct inet_connection_sock *icsk = inet_csk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003455
3456 /* Was it a usable window open? */
3457
Ilpo Järvinen90840de2007-12-31 04:48:41 -08003458 if (!after(TCP_SKB_CB(tcp_send_head(sk))->end_seq, tcp_wnd_end(tp))) {
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07003459 icsk->icsk_backoff = 0;
3460 inet_csk_clear_xmit_timer(sk, ICSK_TIME_PROBE0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003461 /* Socket must be waked up by subsequent tcp_data_snd_check().
3462 * This function is not for random using!
3463 */
3464 } else {
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07003465 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
Arnaldo Carvalho de Melo3f421ba2005-08-09 20:11:08 -07003466 min(icsk->icsk_rto << icsk->icsk_backoff, TCP_RTO_MAX),
3467 TCP_RTO_MAX);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003468 }
3469}
3470
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003471static inline int tcp_ack_is_dubious(const struct sock *sk, const int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003472{
Eric Dumazeta02cec22010-09-22 20:43:57 +00003473 return !(flag & FLAG_NOT_DUP) || (flag & FLAG_CA_ALERT) ||
3474 inet_csk(sk)->icsk_ca_state != TCP_CA_Open;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003475}
3476
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003477static inline int tcp_may_raise_cwnd(const struct sock *sk, const int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003478{
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003479 const struct tcp_sock *tp = tcp_sk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003480 return (!(flag & FLAG_ECE) || tp->snd_cwnd < tp->snd_ssthresh) &&
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003481 !((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_Recovery | TCPF_CA_CWR));
Linus Torvalds1da177e2005-04-16 15:20:36 -07003482}
3483
3484/* Check that window update is acceptable.
3485 * The function assumes that snd_una<=ack<=snd_next.
3486 */
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003487static inline int tcp_may_update_window(const struct tcp_sock *tp,
3488 const u32 ack, const u32 ack_seq,
3489 const u32 nwin)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003490{
Eric Dumazeta02cec22010-09-22 20:43:57 +00003491 return after(ack, tp->snd_una) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07003492 after(ack_seq, tp->snd_wl1) ||
Eric Dumazeta02cec22010-09-22 20:43:57 +00003493 (ack_seq == tp->snd_wl1 && nwin > tp->snd_wnd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003494}
3495
3496/* Update our send window.
3497 *
3498 * Window update algorithm, described in RFC793/RFC1122 (used in linux-2.2
3499 * and in FreeBSD. NetBSD's one is even worse.) is wrong.
3500 */
Eric Dumazetcf533ea2011-10-21 05:22:42 -04003501static int tcp_ack_update_window(struct sock *sk, const struct sk_buff *skb, u32 ack,
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07003502 u32 ack_seq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003503{
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07003504 struct tcp_sock *tp = tcp_sk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003505 int flag = 0;
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -07003506 u32 nwin = ntohs(tcp_hdr(skb)->window);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003507
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -07003508 if (likely(!tcp_hdr(skb)->syn))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003509 nwin <<= tp->rx_opt.snd_wscale;
3510
3511 if (tcp_may_update_window(tp, ack, ack_seq, nwin)) {
3512 flag |= FLAG_WIN_UPDATE;
Hantzis Fotisee7537b2009-03-02 22:42:02 -08003513 tcp_update_wl(tp, ack_seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003514
3515 if (tp->snd_wnd != nwin) {
3516 tp->snd_wnd = nwin;
3517
3518 /* Note, it is the only place, where
3519 * fast path is recovered for sending TCP.
3520 */
Herbert Xu2ad41062005-10-27 18:47:46 +10003521 tp->pred_flags = 0;
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07003522 tcp_fast_path_check(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003523
3524 if (nwin > tp->max_window) {
3525 tp->max_window = nwin;
Arnaldo Carvalho de Melod83d8462005-12-13 23:26:10 -08003526 tcp_sync_mss(sk, inet_csk(sk)->icsk_pmtu_cookie);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003527 }
3528 }
3529 }
3530
3531 tp->snd_una = ack;
3532
3533 return flag;
3534}
3535
Ilpo Järvinen9ead9a12007-02-21 22:56:19 -08003536/* A very conservative spurious RTO response algorithm: reduce cwnd and
3537 * continue in congestion avoidance.
3538 */
3539static void tcp_conservative_spur_to_response(struct tcp_sock *tp)
3540{
3541 tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);
Ilpo Järvinenaa8b6a72007-02-21 23:06:03 -08003542 tp->snd_cwnd_cnt = 0;
Ilpo Järvinen16e90682007-10-11 17:32:31 -07003543 tp->bytes_acked = 0;
Ilpo Järvinen46323652007-05-19 13:56:23 -07003544 TCP_ECN_queue_cwr(tp);
Ilpo Järvinen9ead9a12007-02-21 22:56:19 -08003545 tcp_moderate_cwnd(tp);
3546}
3547
Ilpo Järvinen3cfe3ba2007-02-27 10:09:49 -08003548/* A conservative spurious RTO response algorithm: reduce cwnd using
3549 * rate halving and continue in congestion avoidance.
3550 */
3551static void tcp_ratehalving_spur_to_response(struct sock *sk)
3552{
Ilpo Järvinen3cfe3ba2007-02-27 10:09:49 -08003553 tcp_enter_cwr(sk, 0);
Ilpo Järvinen3cfe3ba2007-02-27 10:09:49 -08003554}
3555
Ilpo Järvinene317f6f2007-03-02 13:34:19 -08003556static void tcp_undo_spur_to_response(struct sock *sk, int flag)
Ilpo Järvinen3cfe3ba2007-02-27 10:09:49 -08003557{
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003558 if (flag & FLAG_ECE)
Ilpo Järvinene317f6f2007-03-02 13:34:19 -08003559 tcp_ratehalving_spur_to_response(sk);
3560 else
David S. Millerf6152732011-03-22 19:37:11 -07003561 tcp_undo_cwr(sk, true);
Ilpo Järvinen3cfe3ba2007-02-27 10:09:49 -08003562}
3563
Ilpo Järvinen30935cf2007-02-21 23:01:36 -08003564/* F-RTO spurious RTO detection algorithm (RFC4138)
3565 *
Ilpo Järvinen6408d202007-02-21 23:04:11 -08003566 * F-RTO affects during two new ACKs following RTO (well, almost, see inline
3567 * comments). State (ACK number) is kept in frto_counter. When ACK advances
3568 * window (but not to or beyond highest sequence sent before RTO):
Ilpo Järvinen30935cf2007-02-21 23:01:36 -08003569 * On First ACK, send two new segments out.
3570 * On Second ACK, RTO was likely spurious. Do spurious response (response
3571 * algorithm is not part of the F-RTO detection algorithm
3572 * given in RFC4138 but can be selected separately).
3573 * Otherwise (basically on duplicate ACK), RTO was (likely) caused by a loss
Ilpo Järvinend551e452007-04-30 00:42:20 -07003574 * and TCP falls back to conventional RTO recovery. F-RTO allows overriding
3575 * of Nagle, this is done using frto_counter states 2 and 3, when a new data
3576 * segment of any size sent during F-RTO, state 2 is upgraded to 3.
Ilpo Järvinen30935cf2007-02-21 23:01:36 -08003577 *
3578 * Rationale: if the RTO was spurious, new ACKs should arrive from the
3579 * original window even after we transmit two new data segments.
3580 *
Ilpo Järvinen4dc26652007-02-21 23:16:11 -08003581 * SACK version:
3582 * on first step, wait until first cumulative ACK arrives, then move to
3583 * the second step. In second step, the next ACK decides.
3584 *
Ilpo Järvinen30935cf2007-02-21 23:01:36 -08003585 * F-RTO is implemented (mainly) in four functions:
3586 * - tcp_use_frto() is used to determine if TCP is can use F-RTO
3587 * - tcp_enter_frto() prepares TCP state on RTO if F-RTO is used, it is
3588 * called when tcp_use_frto() showed green light
3589 * - tcp_process_frto() handles incoming ACKs during F-RTO algorithm
3590 * - tcp_enter_frto_loss() is called if there is not enough evidence
3591 * to prove that the RTO is indeed spurious. It transfers the control
3592 * from F-RTO to the conventional RTO recovery
3593 */
Ilpo Järvinen2e605292007-08-02 19:46:58 -07003594static int tcp_process_frto(struct sock *sk, int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003595{
3596 struct tcp_sock *tp = tcp_sk(sk);
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09003597
Ilpo Järvinen005903b2007-08-09 14:44:16 +03003598 tcp_verify_left_out(tp);
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09003599
Ilpo Järvinen7487c482007-02-21 23:02:30 -08003600 /* Duplicate the behavior from Loss state (fastretrans_alert) */
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003601 if (flag & FLAG_DATA_ACKED)
Ilpo Järvinen7487c482007-02-21 23:02:30 -08003602 inet_csk(sk)->icsk_retransmits = 0;
3603
Ilpo Järvinen009a2e32007-09-20 11:34:38 -07003604 if ((flag & FLAG_NONHEAD_RETRANS_ACKED) ||
3605 ((tp->frto_counter >= 2) && (flag & FLAG_RETRANS_DATA_ACKED)))
3606 tp->undo_marker = 0;
3607
Ilpo Järvinen95c49222007-02-21 23:05:18 -08003608 if (!before(tp->snd_una, tp->frto_highmark)) {
Ilpo Järvinend551e452007-04-30 00:42:20 -07003609 tcp_enter_frto_loss(sk, (tp->frto_counter == 1 ? 2 : 3), flag);
Ilpo Järvinen7c9a4a52007-02-21 23:08:34 -08003610 return 1;
Ilpo Järvinen95c49222007-02-21 23:05:18 -08003611 }
3612
Ilpo Järvinen62ab2222008-05-08 01:09:11 -07003613 if (!tcp_is_sackfrto(tp)) {
Ilpo Järvinen4dc26652007-02-21 23:16:11 -08003614 /* RFC4138 shortcoming in step 2; should also have case c):
3615 * ACK isn't duplicate nor advances window, e.g., opposite dir
3616 * data, winupdate
3617 */
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003618 if (!(flag & FLAG_ANY_PROGRESS) && (flag & FLAG_NOT_DUP))
Ilpo Järvinen4dc26652007-02-21 23:16:11 -08003619 return 1;
Ilpo Järvinen6408d202007-02-21 23:04:11 -08003620
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003621 if (!(flag & FLAG_DATA_ACKED)) {
Ilpo Järvinen4dc26652007-02-21 23:16:11 -08003622 tcp_enter_frto_loss(sk, (tp->frto_counter == 1 ? 0 : 3),
3623 flag);
3624 return 1;
3625 }
3626 } else {
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003627 if (!(flag & FLAG_DATA_ACKED) && (tp->frto_counter == 1)) {
Ilpo Järvinen4dc26652007-02-21 23:16:11 -08003628 /* Prevent sending of new data. */
3629 tp->snd_cwnd = min(tp->snd_cwnd,
3630 tcp_packets_in_flight(tp));
3631 return 1;
3632 }
3633
Ilpo Järvinend551e452007-04-30 00:42:20 -07003634 if ((tp->frto_counter >= 2) &&
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003635 (!(flag & FLAG_FORWARD_PROGRESS) ||
3636 ((flag & FLAG_DATA_SACKED) &&
3637 !(flag & FLAG_ONLY_ORIG_SACKED)))) {
Ilpo Järvinen4dc26652007-02-21 23:16:11 -08003638 /* RFC4138 shortcoming (see comment above) */
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003639 if (!(flag & FLAG_FORWARD_PROGRESS) &&
3640 (flag & FLAG_NOT_DUP))
Ilpo Järvinen4dc26652007-02-21 23:16:11 -08003641 return 1;
3642
3643 tcp_enter_frto_loss(sk, 3, flag);
3644 return 1;
3645 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07003646 }
3647
3648 if (tp->frto_counter == 1) {
Ilpo Järvinen3e6f0492007-12-05 02:20:21 -08003649 /* tcp_may_send_now needs to see updated state */
Linus Torvalds1da177e2005-04-16 15:20:36 -07003650 tp->snd_cwnd = tcp_packets_in_flight(tp) + 2;
Ilpo Järvinen94d0ea72007-02-21 23:07:27 -08003651 tp->frto_counter = 2;
Ilpo Järvinen3e6f0492007-12-05 02:20:21 -08003652
3653 if (!tcp_may_send_now(sk))
3654 tcp_enter_frto_loss(sk, 2, flag);
3655
Ilpo Järvinen7c9a4a52007-02-21 23:08:34 -08003656 return 1;
Ilpo Järvinend551e452007-04-30 00:42:20 -07003657 } else {
Ilpo Järvinen3cfe3ba2007-02-27 10:09:49 -08003658 switch (sysctl_tcp_frto_response) {
3659 case 2:
Ilpo Järvinene317f6f2007-03-02 13:34:19 -08003660 tcp_undo_spur_to_response(sk, flag);
Ilpo Järvinen3cfe3ba2007-02-27 10:09:49 -08003661 break;
3662 case 1:
3663 tcp_conservative_spur_to_response(tp);
3664 break;
3665 default:
3666 tcp_ratehalving_spur_to_response(sk);
3667 break;
Stephen Hemminger3ff50b72007-04-20 17:09:22 -07003668 }
Ilpo Järvinen94d0ea72007-02-21 23:07:27 -08003669 tp->frto_counter = 0;
Ilpo Järvinen009a2e32007-09-20 11:34:38 -07003670 tp->undo_marker = 0;
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07003671 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSPURIOUSRTOS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003672 }
Ilpo Järvinen7c9a4a52007-02-21 23:08:34 -08003673 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003674}
3675
Linus Torvalds1da177e2005-04-16 15:20:36 -07003676/* This routine deals with incoming acks, but not outgoing ones. */
Eric Dumazetcf533ea2011-10-21 05:22:42 -04003677static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003678{
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003679 struct inet_connection_sock *icsk = inet_csk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003680 struct tcp_sock *tp = tcp_sk(sk);
3681 u32 prior_snd_una = tp->snd_una;
3682 u32 ack_seq = TCP_SKB_CB(skb)->seq;
3683 u32 ack = TCP_SKB_CB(skb)->ack_seq;
3684 u32 prior_in_flight;
Ilpo Järvinenc7caf8d2007-11-10 21:22:18 -08003685 u32 prior_fackets;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003686 int prior_packets;
Nandita Dukkipatia262f0c2011-08-21 20:21:57 +00003687 int prior_sacked = tp->sacked_out;
3688 int newly_acked_sacked = 0;
Ilpo Järvinen7c9a4a52007-02-21 23:08:34 -08003689 int frto_cwnd = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003690
John Dykstra96e0bf42009-03-22 21:49:57 -07003691 /* If the ack is older than previous acks
Linus Torvalds1da177e2005-04-16 15:20:36 -07003692 * then we can probably ignore it.
3693 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07003694 if (before(ack, prior_snd_una))
3695 goto old_ack;
3696
John Dykstra96e0bf42009-03-22 21:49:57 -07003697 /* If the ack includes data we haven't sent yet, discard
3698 * this segment (RFC793 Section 3.9).
3699 */
3700 if (after(ack, tp->snd_nxt))
3701 goto invalid_ack;
3702
Ilpo Järvinen2e605292007-08-02 19:46:58 -07003703 if (after(ack, prior_snd_una))
3704 flag |= FLAG_SND_UNA_ADVANCED;
3705
Daikichi Osuga3fdf3f02006-08-29 02:01:44 -07003706 if (sysctl_tcp_abc) {
3707 if (icsk->icsk_ca_state < TCP_CA_CWR)
3708 tp->bytes_acked += ack - prior_snd_una;
3709 else if (icsk->icsk_ca_state == TCP_CA_Loss)
3710 /* we assume just one segment left network */
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003711 tp->bytes_acked += min(ack - prior_snd_una,
3712 tp->mss_cache);
Daikichi Osuga3fdf3f02006-08-29 02:01:44 -07003713 }
Stephen Hemminger9772efb2005-11-10 17:09:53 -08003714
Ilpo Järvinenc7caf8d2007-11-10 21:22:18 -08003715 prior_fackets = tp->fackets_out;
Ilpo Järvinen52d34082007-12-05 02:21:35 -08003716 prior_in_flight = tcp_packets_in_flight(tp);
Ilpo Järvinenc7caf8d2007-11-10 21:22:18 -08003717
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003718 if (!(flag & FLAG_SLOWPATH) && after(ack, prior_snd_una)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003719 /* Window is constant, pure forward advance.
3720 * No more checks are required.
3721 * Note, we use the fact that SND.UNA>=SND.WL2.
3722 */
Hantzis Fotisee7537b2009-03-02 22:42:02 -08003723 tcp_update_wl(tp, ack_seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003724 tp->snd_una = ack;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003725 flag |= FLAG_WIN_UPDATE;
3726
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003727 tcp_ca_event(sk, CA_EVENT_FAST_ACK);
Stephen Hemminger317a76f2005-06-23 12:19:55 -07003728
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07003729 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPHPACKS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003730 } else {
3731 if (ack_seq != TCP_SKB_CB(skb)->end_seq)
3732 flag |= FLAG_DATA;
3733 else
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07003734 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPPUREACKS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003735
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07003736 flag |= tcp_ack_update_window(sk, skb, ack, ack_seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003737
3738 if (TCP_SKB_CB(skb)->sacked)
3739 flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una);
3740
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -07003741 if (TCP_ECN_rcv_ecn_echo(tp, tcp_hdr(skb)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003742 flag |= FLAG_ECE;
3743
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003744 tcp_ca_event(sk, CA_EVENT_SLOW_ACK);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003745 }
3746
3747 /* We passed data and got it acked, remove any soft error
3748 * log. Something worked...
3749 */
3750 sk->sk_err_soft = 0;
David S. Miller4b53fb62008-07-23 16:38:45 -07003751 icsk->icsk_probes_out = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003752 tp->rcv_tstamp = tcp_time_stamp;
3753 prior_packets = tp->packets_out;
3754 if (!prior_packets)
3755 goto no_queue;
3756
Linus Torvalds1da177e2005-04-16 15:20:36 -07003757 /* See if we can take anything off of the retransmit queue. */
Ilpo Järvinen33f5f572008-10-07 14:43:06 -07003758 flag |= tcp_clean_rtx_queue(sk, prior_fackets, prior_snd_una);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003759
Nandita Dukkipatia262f0c2011-08-21 20:21:57 +00003760 newly_acked_sacked = (prior_packets - prior_sacked) -
3761 (tp->packets_out - tp->sacked_out);
3762
Ilpo Järvinene1cd8f72007-11-14 15:55:09 -08003763 if (tp->frto_counter)
3764 frto_cwnd = tcp_process_frto(sk, flag);
Ilpo Järvinen3de96472007-10-01 15:28:48 -07003765 /* Guarantee sacktag reordering detection against wrap-arounds */
3766 if (before(tp->frto_highmark, tp->snd_una))
3767 tp->frto_highmark = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003768
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03003769 if (tcp_ack_is_dubious(sk, flag)) {
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -08003770 /* Advance CWND, if state allows this. */
Ilpo Järvinen7c9a4a52007-02-21 23:08:34 -08003771 if ((flag & FLAG_DATA_ACKED) && !frto_cwnd &&
3772 tcp_may_raise_cwnd(sk, flag))
Ilpo Järvinenc3a05c62007-12-02 00:47:59 +02003773 tcp_cong_avoid(sk, ack, prior_in_flight);
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003774 tcp_fastretrans_alert(sk, prior_packets - tp->packets_out,
Nandita Dukkipatia262f0c2011-08-21 20:21:57 +00003775 newly_acked_sacked, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003776 } else {
Ilpo Järvinen7c9a4a52007-02-21 23:08:34 -08003777 if ((flag & FLAG_DATA_ACKED) && !frto_cwnd)
Ilpo Järvinenc3a05c62007-12-02 00:47:59 +02003778 tcp_cong_avoid(sk, ack, prior_in_flight);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003779 }
3780
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003781 if ((flag & FLAG_FORWARD_PROGRESS) || !(flag & FLAG_NOT_DUP))
Eric Dumazetb6c67122010-04-08 23:03:29 +00003782 dst_confirm(__sk_dst_get(sk));
Linus Torvalds1da177e2005-04-16 15:20:36 -07003783
3784 return 1;
3785
3786no_queue:
Linus Torvalds1da177e2005-04-16 15:20:36 -07003787 /* If this ack opens up a zero window, clear backoff. It was
3788 * being used to time the probes, and is probably far higher than
3789 * it needs to be for normal retransmission.
3790 */
David S. Millerfe067e82007-03-07 12:12:44 -08003791 if (tcp_send_head(sk))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003792 tcp_ack_probe(sk);
3793 return 1;
3794
John Dykstra96e0bf42009-03-22 21:49:57 -07003795invalid_ack:
3796 SOCK_DEBUG(sk, "Ack %u after %u:%u\n", ack, tp->snd_una, tp->snd_nxt);
3797 return -1;
3798
Linus Torvalds1da177e2005-04-16 15:20:36 -07003799old_ack:
Ilpo Järvinen8aca6cb2008-06-04 11:34:22 -07003800 if (TCP_SKB_CB(skb)->sacked) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003801 tcp_sacktag_write_queue(sk, skb, prior_snd_una);
Ilpo Järvinen8aca6cb2008-06-04 11:34:22 -07003802 if (icsk->icsk_ca_state == TCP_CA_Open)
3803 tcp_try_keep_open(sk);
3804 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07003805
John Dykstra96e0bf42009-03-22 21:49:57 -07003806 SOCK_DEBUG(sk, "Ack %u before %u:%u\n", ack, tp->snd_una, tp->snd_nxt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003807 return 0;
3808}
3809
Linus Torvalds1da177e2005-04-16 15:20:36 -07003810/* Look for tcp options. Normally only called on SYN and SYNACK packets.
3811 * But, this can also be called on packets in the established flow when
3812 * the fast version below fails.
3813 */
Eric Dumazetcf533ea2011-10-21 05:22:42 -04003814void tcp_parse_options(const struct sk_buff *skb, struct tcp_options_received *opt_rx,
3815 const u8 **hvpp, int estab)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003816{
Eric Dumazetcf533ea2011-10-21 05:22:42 -04003817 const unsigned char *ptr;
3818 const struct tcphdr *th = tcp_hdr(skb);
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003819 int length = (th->doff * 4) - sizeof(struct tcphdr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003820
Eric Dumazetcf533ea2011-10-21 05:22:42 -04003821 ptr = (const unsigned char *)(th + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003822 opt_rx->saw_tstamp = 0;
3823
Stephen Hemminger2de979b2007-03-08 20:45:19 -08003824 while (length > 0) {
Ilpo Järvinen056834d2007-12-31 14:57:14 -08003825 int opcode = *ptr++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003826 int opsize;
3827
3828 switch (opcode) {
Ilpo Järvinenf038ac82008-01-03 20:36:55 -08003829 case TCPOPT_EOL:
3830 return;
3831 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
3832 length--;
3833 continue;
3834 default:
3835 opsize = *ptr++;
3836 if (opsize < 2) /* "silly options" */
Linus Torvalds1da177e2005-04-16 15:20:36 -07003837 return;
Ilpo Järvinenf038ac82008-01-03 20:36:55 -08003838 if (opsize > length)
3839 return; /* don't parse partial options */
3840 switch (opcode) {
3841 case TCPOPT_MSS:
3842 if (opsize == TCPOLEN_MSS && th->syn && !estab) {
Harvey Harrisond3e2ce32008-05-02 16:26:16 -07003843 u16 in_mss = get_unaligned_be16(ptr);
Ilpo Järvinenf038ac82008-01-03 20:36:55 -08003844 if (in_mss) {
3845 if (opt_rx->user_mss &&
3846 opt_rx->user_mss < in_mss)
3847 in_mss = opt_rx->user_mss;
3848 opt_rx->mss_clamp = in_mss;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003849 }
Stephen Hemminger3ff50b72007-04-20 17:09:22 -07003850 }
Ilpo Järvinenf038ac82008-01-03 20:36:55 -08003851 break;
3852 case TCPOPT_WINDOW:
3853 if (opsize == TCPOLEN_WINDOW && th->syn &&
David S. Millerbb5b7c12009-12-15 20:56:42 -08003854 !estab && sysctl_tcp_window_scaling) {
Ilpo Järvinenf038ac82008-01-03 20:36:55 -08003855 __u8 snd_wscale = *(__u8 *)ptr;
3856 opt_rx->wscale_ok = 1;
3857 if (snd_wscale > 14) {
3858 if (net_ratelimit())
3859 printk(KERN_INFO "tcp_parse_options: Illegal window "
3860 "scaling value %d >14 received.\n",
3861 snd_wscale);
3862 snd_wscale = 14;
3863 }
3864 opt_rx->snd_wscale = snd_wscale;
3865 }
3866 break;
3867 case TCPOPT_TIMESTAMP:
3868 if ((opsize == TCPOLEN_TIMESTAMP) &&
3869 ((estab && opt_rx->tstamp_ok) ||
David S. Millerbb5b7c12009-12-15 20:56:42 -08003870 (!estab && sysctl_tcp_timestamps))) {
Ilpo Järvinenf038ac82008-01-03 20:36:55 -08003871 opt_rx->saw_tstamp = 1;
Harvey Harrisond3e2ce32008-05-02 16:26:16 -07003872 opt_rx->rcv_tsval = get_unaligned_be32(ptr);
3873 opt_rx->rcv_tsecr = get_unaligned_be32(ptr + 4);
Ilpo Järvinenf038ac82008-01-03 20:36:55 -08003874 }
3875 break;
3876 case TCPOPT_SACK_PERM:
3877 if (opsize == TCPOLEN_SACK_PERM && th->syn &&
David S. Millerbb5b7c12009-12-15 20:56:42 -08003878 !estab && sysctl_tcp_sack) {
Ilpo Järvinenf038ac82008-01-03 20:36:55 -08003879 opt_rx->sack_ok = 1;
3880 tcp_sack_reset(opt_rx);
3881 }
3882 break;
Stephen Hemminger3ff50b72007-04-20 17:09:22 -07003883
Ilpo Järvinenf038ac82008-01-03 20:36:55 -08003884 case TCPOPT_SACK:
3885 if ((opsize >= (TCPOLEN_SACK_BASE + TCPOLEN_SACK_PERBLOCK)) &&
3886 !((opsize - TCPOLEN_SACK_BASE) % TCPOLEN_SACK_PERBLOCK) &&
3887 opt_rx->sack_ok) {
3888 TCP_SKB_CB(skb)->sacked = (ptr - 2) - (unsigned char *)th;
3889 }
3890 break;
3891#ifdef CONFIG_TCP_MD5SIG
3892 case TCPOPT_MD5SIG:
3893 /*
3894 * The MD5 Hash has already been
3895 * checked (see tcp_v{4,6}_do_rcv()).
3896 */
3897 break;
3898#endif
William Allen Simpson4957faade2009-12-02 18:25:27 +00003899 case TCPOPT_COOKIE:
3900 /* This option is variable length.
3901 */
3902 switch (opsize) {
3903 case TCPOLEN_COOKIE_BASE:
3904 /* not yet implemented */
3905 break;
3906 case TCPOLEN_COOKIE_PAIR:
3907 /* not yet implemented */
3908 break;
3909 case TCPOLEN_COOKIE_MIN+0:
3910 case TCPOLEN_COOKIE_MIN+2:
3911 case TCPOLEN_COOKIE_MIN+4:
3912 case TCPOLEN_COOKIE_MIN+6:
3913 case TCPOLEN_COOKIE_MAX:
3914 /* 16-bit multiple */
3915 opt_rx->cookie_plus = opsize;
3916 *hvpp = ptr;
Joe Perchesccbd6a52010-05-14 10:58:26 +00003917 break;
William Allen Simpson4957faade2009-12-02 18:25:27 +00003918 default:
3919 /* ignore option */
3920 break;
Joe Perchesccbd6a52010-05-14 10:58:26 +00003921 }
William Allen Simpson4957faade2009-12-02 18:25:27 +00003922 break;
Joe Perchesccbd6a52010-05-14 10:58:26 +00003923 }
Ilpo Järvinenf038ac82008-01-03 20:36:55 -08003924
3925 ptr += opsize-2;
3926 length -= opsize;
Stephen Hemminger3ff50b72007-04-20 17:09:22 -07003927 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07003928 }
3929}
Eric Dumazet4bc2f182010-07-09 21:22:10 +00003930EXPORT_SYMBOL(tcp_parse_options);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003931
Eric Dumazetcf533ea2011-10-21 05:22:42 -04003932static int tcp_parse_aligned_timestamp(struct tcp_sock *tp, const struct tcphdr *th)
Ilpo Järvinena4356b22008-08-23 05:12:29 -07003933{
Eric Dumazetcf533ea2011-10-21 05:22:42 -04003934 const __be32 *ptr = (const __be32 *)(th + 1);
Ilpo Järvinena4356b22008-08-23 05:12:29 -07003935
3936 if (*ptr == htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16)
3937 | (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP)) {
3938 tp->rx_opt.saw_tstamp = 1;
3939 ++ptr;
3940 tp->rx_opt.rcv_tsval = ntohl(*ptr);
3941 ++ptr;
3942 tp->rx_opt.rcv_tsecr = ntohl(*ptr);
3943 return 1;
3944 }
3945 return 0;
3946}
3947
Linus Torvalds1da177e2005-04-16 15:20:36 -07003948/* Fast parse options. This hopes to only see timestamps.
3949 * If it is wrong it falls back on tcp_parse_options().
3950 */
Eric Dumazetcf533ea2011-10-21 05:22:42 -04003951static int tcp_fast_parse_options(const struct sk_buff *skb,
3952 const struct tcphdr *th,
3953 struct tcp_sock *tp, const u8 **hvpp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003954{
William Allen Simpson4957faade2009-12-02 18:25:27 +00003955 /* In the spirit of fast parsing, compare doff directly to constant
3956 * values. Because equality is used, short doff can be ignored here.
3957 */
3958 if (th->doff == (sizeof(*th) / 4)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003959 tp->rx_opt.saw_tstamp = 0;
3960 return 0;
3961 } else if (tp->rx_opt.tstamp_ok &&
William Allen Simpson4957faade2009-12-02 18:25:27 +00003962 th->doff == ((sizeof(*th) + TCPOLEN_TSTAMP_ALIGNED) / 4)) {
Ilpo Järvinena4356b22008-08-23 05:12:29 -07003963 if (tcp_parse_aligned_timestamp(tp, th))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003964 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003965 }
David S. Millerbb5b7c12009-12-15 20:56:42 -08003966 tcp_parse_options(skb, &tp->rx_opt, hvpp, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003967 return 1;
3968}
3969
YOSHIFUJI Hideaki7d5d5522008-04-17 12:29:53 +09003970#ifdef CONFIG_TCP_MD5SIG
3971/*
3972 * Parse MD5 Signature option
3973 */
Eric Dumazetcf533ea2011-10-21 05:22:42 -04003974const u8 *tcp_parse_md5sig_option(const struct tcphdr *th)
YOSHIFUJI Hideaki7d5d5522008-04-17 12:29:53 +09003975{
Eric Dumazetcf533ea2011-10-21 05:22:42 -04003976 int length = (th->doff << 2) - sizeof(*th);
3977 const u8 *ptr = (const u8 *)(th + 1);
YOSHIFUJI Hideaki7d5d5522008-04-17 12:29:53 +09003978
3979 /* If the TCP option is too short, we can short cut */
3980 if (length < TCPOLEN_MD5SIG)
3981 return NULL;
3982
3983 while (length > 0) {
3984 int opcode = *ptr++;
3985 int opsize;
3986
3987 switch(opcode) {
3988 case TCPOPT_EOL:
3989 return NULL;
3990 case TCPOPT_NOP:
3991 length--;
3992 continue;
3993 default:
3994 opsize = *ptr++;
3995 if (opsize < 2 || opsize > length)
3996 return NULL;
3997 if (opcode == TCPOPT_MD5SIG)
Dmitry Popovba78e2d2010-08-07 20:24:28 -07003998 return opsize == TCPOLEN_MD5SIG ? ptr : NULL;
YOSHIFUJI Hideaki7d5d5522008-04-17 12:29:53 +09003999 }
4000 ptr += opsize - 2;
4001 length -= opsize;
4002 }
4003 return NULL;
4004}
Eric Dumazet4bc2f182010-07-09 21:22:10 +00004005EXPORT_SYMBOL(tcp_parse_md5sig_option);
YOSHIFUJI Hideaki7d5d5522008-04-17 12:29:53 +09004006#endif
4007
Linus Torvalds1da177e2005-04-16 15:20:36 -07004008static inline void tcp_store_ts_recent(struct tcp_sock *tp)
4009{
4010 tp->rx_opt.ts_recent = tp->rx_opt.rcv_tsval;
James Morris9d729f72007-03-04 16:12:44 -08004011 tp->rx_opt.ts_recent_stamp = get_seconds();
Linus Torvalds1da177e2005-04-16 15:20:36 -07004012}
4013
4014static inline void tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq)
4015{
4016 if (tp->rx_opt.saw_tstamp && !after(seq, tp->rcv_wup)) {
4017 /* PAWS bug workaround wrt. ACK frames, the PAWS discard
4018 * extra check below makes sure this can only happen
4019 * for pure ACK frames. -DaveM
4020 *
4021 * Not only, also it occurs for expired timestamps.
4022 */
4023
Ilpo Järvinenc887e6d2009-03-14 14:23:03 +00004024 if (tcp_paws_check(&tp->rx_opt, 0))
Linus Torvalds1da177e2005-04-16 15:20:36 -07004025 tcp_store_ts_recent(tp);
4026 }
4027}
4028
4029/* Sorry, PAWS as specified is broken wrt. pure-ACKs -DaveM
4030 *
4031 * It is not fatal. If this ACK does _not_ change critical state (seqs, window)
4032 * it can pass through stack. So, the following predicate verifies that
4033 * this segment is not used for anything but congestion avoidance or
4034 * fast retransmit. Moreover, we even are able to eliminate most of such
4035 * second order effects, if we apply some small "replay" window (~RTO)
4036 * to timestamp space.
4037 *
4038 * All these measures still do not guarantee that we reject wrapped ACKs
4039 * on networks with high bandwidth, when sequence space is recycled fastly,
4040 * but it guarantees that such events will be very rare and do not affect
4041 * connection seriously. This doesn't look nice, but alas, PAWS is really
4042 * buggy extension.
4043 *
4044 * [ Later note. Even worse! It is buggy for segments _with_ data. RFC
4045 * states that events when retransmit arrives after original data are rare.
4046 * It is a blatant lie. VJ forgot about fast retransmit! 8)8) It is
4047 * the biggest problem on large power networks even with minor reordering.
4048 * OK, let's give it small replay window. If peer clock is even 1hz, it is safe
4049 * up to bandwidth of 18Gigabit/sec. 8) ]
4050 */
4051
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07004052static int tcp_disordered_ack(const struct sock *sk, const struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004053{
Eric Dumazetcf533ea2011-10-21 05:22:42 -04004054 const struct tcp_sock *tp = tcp_sk(sk);
4055 const struct tcphdr *th = tcp_hdr(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004056 u32 seq = TCP_SKB_CB(skb)->seq;
4057 u32 ack = TCP_SKB_CB(skb)->ack_seq;
4058
4059 return (/* 1. Pure ACK with correct sequence number. */
4060 (th->ack && seq == TCP_SKB_CB(skb)->end_seq && seq == tp->rcv_nxt) &&
4061
4062 /* 2. ... and duplicate ACK. */
4063 ack == tp->snd_una &&
4064
4065 /* 3. ... and does not update window. */
4066 !tcp_may_update_window(tp, ack, seq, ntohs(th->window) << tp->rx_opt.snd_wscale) &&
4067
4068 /* 4. ... and sits in replay window. */
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07004069 (s32)(tp->rx_opt.ts_recent - tp->rx_opt.rcv_tsval) <= (inet_csk(sk)->icsk_rto * 1024) / HZ);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004070}
4071
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004072static inline int tcp_paws_discard(const struct sock *sk,
4073 const struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004074{
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07004075 const struct tcp_sock *tp = tcp_sk(sk);
Ilpo Järvinenc887e6d2009-03-14 14:23:03 +00004076
4077 return !tcp_paws_check(&tp->rx_opt, TCP_PAWS_WINDOW) &&
4078 !tcp_disordered_ack(sk, skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004079}
4080
4081/* Check segment sequence number for validity.
4082 *
4083 * Segment controls are considered valid, if the segment
4084 * fits to the window after truncation to the window. Acceptability
4085 * of data (and SYN, FIN, of course) is checked separately.
4086 * See tcp_data_queue(), for example.
4087 *
4088 * Also, controls (RST is main one) are accepted using RCV.WUP instead
4089 * of RCV.NXT. Peer still did not advance his SND.UNA when we
4090 * delayed ACK, so that hisSND.UNA<=ourRCV.WUP.
4091 * (borrowed from freebsd)
4092 */
4093
Eric Dumazetcf533ea2011-10-21 05:22:42 -04004094static inline int tcp_sequence(const struct tcp_sock *tp, u32 seq, u32 end_seq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004095{
4096 return !before(end_seq, tp->rcv_wup) &&
4097 !after(seq, tp->rcv_nxt + tcp_receive_window(tp));
4098}
4099
4100/* When we get a reset we do this. */
4101static void tcp_reset(struct sock *sk)
4102{
4103 /* We want the right error as BSD sees it (and indeed as we do). */
4104 switch (sk->sk_state) {
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004105 case TCP_SYN_SENT:
4106 sk->sk_err = ECONNREFUSED;
4107 break;
4108 case TCP_CLOSE_WAIT:
4109 sk->sk_err = EPIPE;
4110 break;
4111 case TCP_CLOSE:
4112 return;
4113 default:
4114 sk->sk_err = ECONNRESET;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004115 }
Tom Marshalla4d25802010-09-20 15:42:05 -07004116 /* This barrier is coupled with smp_rmb() in tcp_poll() */
4117 smp_wmb();
Linus Torvalds1da177e2005-04-16 15:20:36 -07004118
4119 if (!sock_flag(sk, SOCK_DEAD))
4120 sk->sk_error_report(sk);
4121
4122 tcp_done(sk);
4123}
4124
4125/*
4126 * Process the FIN bit. This now behaves as it is supposed to work
4127 * and the FIN takes effect when it is validly part of sequence
4128 * space. Not before when we get holes.
4129 *
4130 * If we are ESTABLISHED, a received fin moves us to CLOSE-WAIT
4131 * (and thence onto LAST-ACK and finally, CLOSE, we never enter
4132 * TIME-WAIT)
4133 *
4134 * If we are in FINWAIT-1, a received FIN indicates simultaneous
4135 * close and we go into CLOSING (and later onto TIME-WAIT)
4136 *
4137 * If we are in FINWAIT-2, a received FIN moves us to TIME-WAIT.
4138 */
Eric Dumazet20c4cb72011-10-20 17:44:03 -04004139static void tcp_fin(struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004140{
4141 struct tcp_sock *tp = tcp_sk(sk);
4142
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07004143 inet_csk_schedule_ack(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004144
4145 sk->sk_shutdown |= RCV_SHUTDOWN;
4146 sock_set_flag(sk, SOCK_DONE);
4147
4148 switch (sk->sk_state) {
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004149 case TCP_SYN_RECV:
4150 case TCP_ESTABLISHED:
4151 /* Move to CLOSE_WAIT */
4152 tcp_set_state(sk, TCP_CLOSE_WAIT);
4153 inet_csk(sk)->icsk_ack.pingpong = 1;
4154 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004155
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004156 case TCP_CLOSE_WAIT:
4157 case TCP_CLOSING:
4158 /* Received a retransmission of the FIN, do
4159 * nothing.
4160 */
4161 break;
4162 case TCP_LAST_ACK:
4163 /* RFC793: Remain in the LAST-ACK state. */
4164 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004165
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004166 case TCP_FIN_WAIT1:
4167 /* This case occurs when a simultaneous close
4168 * happens, we must ack the received FIN and
4169 * enter the CLOSING state.
4170 */
4171 tcp_send_ack(sk);
4172 tcp_set_state(sk, TCP_CLOSING);
4173 break;
4174 case TCP_FIN_WAIT2:
4175 /* Received a FIN -- send ACK and enter TIME_WAIT. */
4176 tcp_send_ack(sk);
4177 tcp_time_wait(sk, TCP_TIME_WAIT, 0);
4178 break;
4179 default:
4180 /* Only TCP_LISTEN and TCP_CLOSE are left, in these
4181 * cases we should never reach this piece of code.
4182 */
4183 printk(KERN_ERR "%s: Impossible, sk->sk_state=%d\n",
Harvey Harrison0dc47872008-03-05 20:47:47 -08004184 __func__, sk->sk_state);
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004185 break;
Stephen Hemminger3ff50b72007-04-20 17:09:22 -07004186 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07004187
4188 /* It _is_ possible, that we have something out-of-order _after_ FIN.
4189 * Probably, we should reset in this case. For now drop them.
4190 */
4191 __skb_queue_purge(&tp->out_of_order_queue);
Ilpo Järvinene60402d2007-08-09 15:14:46 +03004192 if (tcp_is_sack(tp))
Linus Torvalds1da177e2005-04-16 15:20:36 -07004193 tcp_sack_reset(&tp->rx_opt);
Hideo Aoki3ab224b2007-12-31 00:11:19 -08004194 sk_mem_reclaim(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004195
4196 if (!sock_flag(sk, SOCK_DEAD)) {
4197 sk->sk_state_change(sk);
4198
4199 /* Do not send POLL_HUP for half duplex close. */
4200 if (sk->sk_shutdown == SHUTDOWN_MASK ||
4201 sk->sk_state == TCP_CLOSE)
Pavel Emelyanov8d8ad9d2007-11-26 20:10:50 +08004202 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004203 else
Pavel Emelyanov8d8ad9d2007-11-26 20:10:50 +08004204 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004205 }
4206}
4207
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004208static inline int tcp_sack_extend(struct tcp_sack_block *sp, u32 seq,
4209 u32 end_seq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004210{
4211 if (!after(seq, sp->end_seq) && !after(sp->start_seq, end_seq)) {
4212 if (before(seq, sp->start_seq))
4213 sp->start_seq = seq;
4214 if (after(end_seq, sp->end_seq))
4215 sp->end_seq = end_seq;
4216 return 1;
4217 }
4218 return 0;
4219}
4220
Pavel Emelyanov1ed83462008-07-16 20:29:51 -07004221static void tcp_dsack_set(struct sock *sk, u32 seq, u32 end_seq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004222{
Pavel Emelyanov1ed83462008-07-16 20:29:51 -07004223 struct tcp_sock *tp = tcp_sk(sk);
4224
David S. Millerbb5b7c12009-12-15 20:56:42 -08004225 if (tcp_is_sack(tp) && sysctl_tcp_dsack) {
Pavel Emelyanov40b215e2008-07-03 01:05:41 -07004226 int mib_idx;
4227
Linus Torvalds1da177e2005-04-16 15:20:36 -07004228 if (before(seq, tp->rcv_nxt))
Pavel Emelyanov40b215e2008-07-03 01:05:41 -07004229 mib_idx = LINUX_MIB_TCPDSACKOLDSENT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004230 else
Pavel Emelyanov40b215e2008-07-03 01:05:41 -07004231 mib_idx = LINUX_MIB_TCPDSACKOFOSENT;
4232
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07004233 NET_INC_STATS_BH(sock_net(sk), mib_idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004234
4235 tp->rx_opt.dsack = 1;
4236 tp->duplicate_sack[0].start_seq = seq;
4237 tp->duplicate_sack[0].end_seq = end_seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004238 }
4239}
4240
Pavel Emelyanov1ed83462008-07-16 20:29:51 -07004241static void tcp_dsack_extend(struct sock *sk, u32 seq, u32 end_seq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004242{
Pavel Emelyanov1ed83462008-07-16 20:29:51 -07004243 struct tcp_sock *tp = tcp_sk(sk);
4244
Linus Torvalds1da177e2005-04-16 15:20:36 -07004245 if (!tp->rx_opt.dsack)
Pavel Emelyanov1ed83462008-07-16 20:29:51 -07004246 tcp_dsack_set(sk, seq, end_seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004247 else
4248 tcp_sack_extend(tp->duplicate_sack, seq, end_seq);
4249}
4250
Eric Dumazetcf533ea2011-10-21 05:22:42 -04004251static void tcp_send_dupack(struct sock *sk, const struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004252{
4253 struct tcp_sock *tp = tcp_sk(sk);
4254
4255 if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
4256 before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) {
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07004257 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKLOST);
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07004258 tcp_enter_quickack_mode(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004259
David S. Millerbb5b7c12009-12-15 20:56:42 -08004260 if (tcp_is_sack(tp) && sysctl_tcp_dsack) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07004261 u32 end_seq = TCP_SKB_CB(skb)->end_seq;
4262
4263 if (after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt))
4264 end_seq = tp->rcv_nxt;
Pavel Emelyanov1ed83462008-07-16 20:29:51 -07004265 tcp_dsack_set(sk, TCP_SKB_CB(skb)->seq, end_seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004266 }
4267 }
4268
4269 tcp_send_ack(sk);
4270}
4271
4272/* These routines update the SACK block as out-of-order packets arrive or
4273 * in-order packets close up the sequence space.
4274 */
4275static void tcp_sack_maybe_coalesce(struct tcp_sock *tp)
4276{
4277 int this_sack;
4278 struct tcp_sack_block *sp = &tp->selective_acks[0];
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004279 struct tcp_sack_block *swalk = sp + 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004280
4281 /* See if the recent change to the first SACK eats into
4282 * or hits the sequence space of other SACK blocks, if so coalesce.
4283 */
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004284 for (this_sack = 1; this_sack < tp->rx_opt.num_sacks;) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07004285 if (tcp_sack_extend(sp, swalk->start_seq, swalk->end_seq)) {
4286 int i;
4287
4288 /* Zap SWALK, by moving every further SACK up by one slot.
4289 * Decrease num_sacks.
4290 */
4291 tp->rx_opt.num_sacks--;
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004292 for (i = this_sack; i < tp->rx_opt.num_sacks; i++)
4293 sp[i] = sp[i + 1];
Linus Torvalds1da177e2005-04-16 15:20:36 -07004294 continue;
4295 }
4296 this_sack++, swalk++;
4297 }
4298}
4299
Linus Torvalds1da177e2005-04-16 15:20:36 -07004300static void tcp_sack_new_ofo_skb(struct sock *sk, u32 seq, u32 end_seq)
4301{
4302 struct tcp_sock *tp = tcp_sk(sk);
4303 struct tcp_sack_block *sp = &tp->selective_acks[0];
4304 int cur_sacks = tp->rx_opt.num_sacks;
4305 int this_sack;
4306
4307 if (!cur_sacks)
4308 goto new_sack;
4309
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004310 for (this_sack = 0; this_sack < cur_sacks; this_sack++, sp++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07004311 if (tcp_sack_extend(sp, seq, end_seq)) {
4312 /* Rotate this_sack to the first one. */
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004313 for (; this_sack > 0; this_sack--, sp--)
Ilpo Järvinena0bffff2009-03-21 13:36:17 -07004314 swap(*sp, *(sp - 1));
Linus Torvalds1da177e2005-04-16 15:20:36 -07004315 if (cur_sacks > 1)
4316 tcp_sack_maybe_coalesce(tp);
4317 return;
4318 }
4319 }
4320
4321 /* Could not find an adjacent existing SACK, build a new one,
4322 * put it at the front, and shift everyone else down. We
4323 * always know there is at least one SACK present already here.
4324 *
4325 * If the sack array is full, forget about the last one.
4326 */
Adam Langley4389dde2008-07-19 00:07:02 -07004327 if (this_sack >= TCP_NUM_SACKS) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07004328 this_sack--;
4329 tp->rx_opt.num_sacks--;
4330 sp--;
4331 }
Stephen Hemminger2de979b2007-03-08 20:45:19 -08004332 for (; this_sack > 0; this_sack--, sp--)
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004333 *sp = *(sp - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004334
4335new_sack:
4336 /* Build the new head SACK, and we're done. */
4337 sp->start_seq = seq;
4338 sp->end_seq = end_seq;
4339 tp->rx_opt.num_sacks++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004340}
4341
4342/* RCV.NXT advances, some SACKs should be eaten. */
4343
4344static void tcp_sack_remove(struct tcp_sock *tp)
4345{
4346 struct tcp_sack_block *sp = &tp->selective_acks[0];
4347 int num_sacks = tp->rx_opt.num_sacks;
4348 int this_sack;
4349
4350 /* Empty ofo queue, hence, all the SACKs are eaten. Clear. */
David S. Millerb03efcf2005-07-08 14:57:23 -07004351 if (skb_queue_empty(&tp->out_of_order_queue)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07004352 tp->rx_opt.num_sacks = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004353 return;
4354 }
4355
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004356 for (this_sack = 0; this_sack < num_sacks;) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07004357 /* Check if the start of the sack is covered by RCV.NXT. */
4358 if (!before(tp->rcv_nxt, sp->start_seq)) {
4359 int i;
4360
4361 /* RCV.NXT must cover all the block! */
Ilpo Järvinen547b7922008-07-25 21:43:18 -07004362 WARN_ON(before(tp->rcv_nxt, sp->end_seq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07004363
4364 /* Zap this SACK, by moving forward any other SACKS. */
4365 for (i=this_sack+1; i < num_sacks; i++)
4366 tp->selective_acks[i-1] = tp->selective_acks[i];
4367 num_sacks--;
4368 continue;
4369 }
4370 this_sack++;
4371 sp++;
4372 }
Ilpo Järvinen5861f8e2009-03-14 14:23:01 +00004373 tp->rx_opt.num_sacks = num_sacks;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004374}
4375
4376/* This one checks to see if we can put data from the
4377 * out_of_order queue into the receive_queue.
4378 */
4379static void tcp_ofo_queue(struct sock *sk)
4380{
4381 struct tcp_sock *tp = tcp_sk(sk);
4382 __u32 dsack_high = tp->rcv_nxt;
4383 struct sk_buff *skb;
4384
4385 while ((skb = skb_peek(&tp->out_of_order_queue)) != NULL) {
4386 if (after(TCP_SKB_CB(skb)->seq, tp->rcv_nxt))
4387 break;
4388
4389 if (before(TCP_SKB_CB(skb)->seq, dsack_high)) {
4390 __u32 dsack = dsack_high;
4391 if (before(TCP_SKB_CB(skb)->end_seq, dsack_high))
4392 dsack_high = TCP_SKB_CB(skb)->end_seq;
Pavel Emelyanov1ed83462008-07-16 20:29:51 -07004393 tcp_dsack_extend(sk, TCP_SKB_CB(skb)->seq, dsack);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004394 }
4395
4396 if (!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt)) {
Frans Popb1383382010-03-24 07:57:28 +00004397 SOCK_DEBUG(sk, "ofo packet was already received\n");
David S. Miller8728b832005-08-09 19:25:21 -07004398 __skb_unlink(skb, &tp->out_of_order_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004399 __kfree_skb(skb);
4400 continue;
4401 }
4402 SOCK_DEBUG(sk, "ofo requeuing : rcv_next %X seq %X - %X\n",
4403 tp->rcv_nxt, TCP_SKB_CB(skb)->seq,
4404 TCP_SKB_CB(skb)->end_seq);
4405
David S. Miller8728b832005-08-09 19:25:21 -07004406 __skb_unlink(skb, &tp->out_of_order_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004407 __skb_queue_tail(&sk->sk_receive_queue, skb);
4408 tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -07004409 if (tcp_hdr(skb)->fin)
Eric Dumazet20c4cb72011-10-20 17:44:03 -04004410 tcp_fin(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004411 }
4412}
4413
Vitaliy Gusev56f367b2008-04-15 20:26:34 -07004414static int tcp_prune_ofo_queue(struct sock *sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004415static int tcp_prune_queue(struct sock *sk);
4416
Vitaliy Gusevb000cd32008-04-15 00:33:38 -07004417static inline int tcp_try_rmem_schedule(struct sock *sk, unsigned int size)
4418{
4419 if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
4420 !sk_rmem_schedule(sk, size)) {
4421
4422 if (tcp_prune_queue(sk) < 0)
4423 return -1;
4424
4425 if (!sk_rmem_schedule(sk, size)) {
Vitaliy Gusev56f367b2008-04-15 20:26:34 -07004426 if (!tcp_prune_ofo_queue(sk))
4427 return -1;
4428
Vitaliy Gusevb000cd32008-04-15 00:33:38 -07004429 if (!sk_rmem_schedule(sk, size))
4430 return -1;
4431 }
4432 }
4433 return 0;
4434}
4435
Linus Torvalds1da177e2005-04-16 15:20:36 -07004436static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
4437{
Eric Dumazetcf533ea2011-10-21 05:22:42 -04004438 const struct tcphdr *th = tcp_hdr(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004439 struct tcp_sock *tp = tcp_sk(sk);
4440 int eaten = -1;
4441
4442 if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq)
4443 goto drop;
4444
Eric Dumazetf84af322010-04-28 15:31:51 -07004445 skb_dst_drop(skb);
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004446 __skb_pull(skb, th->doff * 4);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004447
4448 TCP_ECN_accept_cwr(tp, skb);
4449
Ilpo Järvinen5861f8e2009-03-14 14:23:01 +00004450 tp->rx_opt.dsack = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004451
4452 /* Queue data for delivery to the user.
4453 * Packets in sequence go to the receive queue.
4454 * Out of sequence packets to the out_of_order_queue.
4455 */
4456 if (TCP_SKB_CB(skb)->seq == tp->rcv_nxt) {
4457 if (tcp_receive_window(tp) == 0)
4458 goto out_of_window;
4459
4460 /* Ok. In sequence. In window. */
4461 if (tp->ucopy.task == current &&
4462 tp->copied_seq == tp->rcv_nxt && tp->ucopy.len &&
4463 sock_owned_by_user(sk) && !tp->urg_data) {
4464 int chunk = min_t(unsigned int, skb->len,
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004465 tp->ucopy.len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004466
4467 __set_current_state(TASK_RUNNING);
4468
4469 local_bh_enable();
4470 if (!skb_copy_datagram_iovec(skb, 0, tp->ucopy.iov, chunk)) {
4471 tp->ucopy.len -= chunk;
4472 tp->copied_seq += chunk;
Jerry Chu44f53242011-01-25 13:46:30 -08004473 eaten = (chunk == skb->len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004474 tcp_rcv_space_adjust(sk);
4475 }
4476 local_bh_disable();
4477 }
4478
4479 if (eaten <= 0) {
4480queue_and_out:
4481 if (eaten < 0 &&
Vitaliy Gusevb000cd32008-04-15 00:33:38 -07004482 tcp_try_rmem_schedule(sk, skb->truesize))
4483 goto drop;
4484
Hideo Aoki3ab224b2007-12-31 00:11:19 -08004485 skb_set_owner_r(skb, sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004486 __skb_queue_tail(&sk->sk_receive_queue, skb);
4487 }
4488 tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
Stephen Hemminger2de979b2007-03-08 20:45:19 -08004489 if (skb->len)
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07004490 tcp_event_data_recv(sk, skb);
Stephen Hemminger2de979b2007-03-08 20:45:19 -08004491 if (th->fin)
Eric Dumazet20c4cb72011-10-20 17:44:03 -04004492 tcp_fin(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004493
David S. Millerb03efcf2005-07-08 14:57:23 -07004494 if (!skb_queue_empty(&tp->out_of_order_queue)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07004495 tcp_ofo_queue(sk);
4496
4497 /* RFC2581. 4.2. SHOULD send immediate ACK, when
4498 * gap in queue is filled.
4499 */
David S. Millerb03efcf2005-07-08 14:57:23 -07004500 if (skb_queue_empty(&tp->out_of_order_queue))
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07004501 inet_csk(sk)->icsk_ack.pingpong = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004502 }
4503
4504 if (tp->rx_opt.num_sacks)
4505 tcp_sack_remove(tp);
4506
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07004507 tcp_fast_path_check(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004508
4509 if (eaten > 0)
4510 __kfree_skb(skb);
4511 else if (!sock_flag(sk, SOCK_DEAD))
4512 sk->sk_data_ready(sk, 0);
4513 return;
4514 }
4515
4516 if (!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt)) {
4517 /* A retransmit, 2nd most common case. Force an immediate ack. */
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07004518 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKLOST);
Pavel Emelyanov1ed83462008-07-16 20:29:51 -07004519 tcp_dsack_set(sk, TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004520
4521out_of_window:
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07004522 tcp_enter_quickack_mode(sk);
4523 inet_csk_schedule_ack(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004524drop:
4525 __kfree_skb(skb);
4526 return;
4527 }
4528
4529 /* Out of window. F.e. zero window probe. */
4530 if (!before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt + tcp_receive_window(tp)))
4531 goto out_of_window;
4532
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07004533 tcp_enter_quickack_mode(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004534
4535 if (before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) {
4536 /* Partial packet, seq < rcv_next < end_seq */
4537 SOCK_DEBUG(sk, "partial packet: rcv_next %X seq %X - %X\n",
4538 tp->rcv_nxt, TCP_SKB_CB(skb)->seq,
4539 TCP_SKB_CB(skb)->end_seq);
4540
Pavel Emelyanov1ed83462008-07-16 20:29:51 -07004541 tcp_dsack_set(sk, TCP_SKB_CB(skb)->seq, tp->rcv_nxt);
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09004542
Linus Torvalds1da177e2005-04-16 15:20:36 -07004543 /* If window is closed, drop tail of packet. But after
4544 * remembering D-SACK for its head made in previous line.
4545 */
4546 if (!tcp_receive_window(tp))
4547 goto out_of_window;
4548 goto queue_and_out;
4549 }
4550
4551 TCP_ECN_check_ce(tp, skb);
4552
Vitaliy Gusevb000cd32008-04-15 00:33:38 -07004553 if (tcp_try_rmem_schedule(sk, skb->truesize))
4554 goto drop;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004555
4556 /* Disable header prediction. */
4557 tp->pred_flags = 0;
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07004558 inet_csk_schedule_ack(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004559
4560 SOCK_DEBUG(sk, "out of order segment: rcv_next %X seq %X - %X\n",
4561 tp->rcv_nxt, TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq);
4562
Hideo Aoki3ab224b2007-12-31 00:11:19 -08004563 skb_set_owner_r(skb, sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004564
4565 if (!skb_peek(&tp->out_of_order_queue)) {
4566 /* Initial out of order segment, build 1 SACK. */
Ilpo Järvinene60402d2007-08-09 15:14:46 +03004567 if (tcp_is_sack(tp)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07004568 tp->rx_opt.num_sacks = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004569 tp->selective_acks[0].start_seq = TCP_SKB_CB(skb)->seq;
4570 tp->selective_acks[0].end_seq =
4571 TCP_SKB_CB(skb)->end_seq;
4572 }
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004573 __skb_queue_head(&tp->out_of_order_queue, skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004574 } else {
David S. Miller91521942009-05-28 21:35:47 -07004575 struct sk_buff *skb1 = skb_peek_tail(&tp->out_of_order_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004576 u32 seq = TCP_SKB_CB(skb)->seq;
4577 u32 end_seq = TCP_SKB_CB(skb)->end_seq;
4578
4579 if (seq == TCP_SKB_CB(skb1)->end_seq) {
Gerrit Renker7de6c032008-04-14 00:05:09 -07004580 __skb_queue_after(&tp->out_of_order_queue, skb1, skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004581
4582 if (!tp->rx_opt.num_sacks ||
4583 tp->selective_acks[0].end_seq != seq)
4584 goto add_sack;
4585
4586 /* Common case: data arrive in order after hole. */
4587 tp->selective_acks[0].end_seq = end_seq;
4588 return;
4589 }
4590
4591 /* Find place to insert this segment. */
David S. Miller91521942009-05-28 21:35:47 -07004592 while (1) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07004593 if (!after(TCP_SKB_CB(skb1)->seq, seq))
4594 break;
David S. Miller91521942009-05-28 21:35:47 -07004595 if (skb_queue_is_first(&tp->out_of_order_queue, skb1)) {
4596 skb1 = NULL;
4597 break;
4598 }
4599 skb1 = skb_queue_prev(&tp->out_of_order_queue, skb1);
4600 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07004601
4602 /* Do skb overlap to previous one? */
David S. Miller91521942009-05-28 21:35:47 -07004603 if (skb1 && before(seq, TCP_SKB_CB(skb1)->end_seq)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07004604 if (!after(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
4605 /* All the bits are present. Drop. */
4606 __kfree_skb(skb);
Pavel Emelyanov1ed83462008-07-16 20:29:51 -07004607 tcp_dsack_set(sk, seq, end_seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004608 goto add_sack;
4609 }
4610 if (after(seq, TCP_SKB_CB(skb1)->seq)) {
4611 /* Partial overlap. */
Pavel Emelyanov1ed83462008-07-16 20:29:51 -07004612 tcp_dsack_set(sk, seq,
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004613 TCP_SKB_CB(skb1)->end_seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004614 } else {
David S. Miller91521942009-05-28 21:35:47 -07004615 if (skb_queue_is_first(&tp->out_of_order_queue,
4616 skb1))
4617 skb1 = NULL;
4618 else
4619 skb1 = skb_queue_prev(
4620 &tp->out_of_order_queue,
4621 skb1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004622 }
4623 }
David S. Miller91521942009-05-28 21:35:47 -07004624 if (!skb1)
4625 __skb_queue_head(&tp->out_of_order_queue, skb);
4626 else
4627 __skb_queue_after(&tp->out_of_order_queue, skb1, skb);
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09004628
Linus Torvalds1da177e2005-04-16 15:20:36 -07004629 /* And clean segments covered by new one as whole. */
Ilpo Järvinen2df90012009-05-29 15:02:29 -07004630 while (!skb_queue_is_last(&tp->out_of_order_queue, skb)) {
4631 skb1 = skb_queue_next(&tp->out_of_order_queue, skb);
David S. Miller91521942009-05-28 21:35:47 -07004632
Ilpo Järvinen2df90012009-05-29 15:02:29 -07004633 if (!after(end_seq, TCP_SKB_CB(skb1)->seq))
4634 break;
4635 if (before(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
Pavel Emelyanov1ed83462008-07-16 20:29:51 -07004636 tcp_dsack_extend(sk, TCP_SKB_CB(skb1)->seq,
Ilpo Järvinen2df90012009-05-29 15:02:29 -07004637 end_seq);
4638 break;
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004639 }
Ilpo Järvinen2df90012009-05-29 15:02:29 -07004640 __skb_unlink(skb1, &tp->out_of_order_queue);
4641 tcp_dsack_extend(sk, TCP_SKB_CB(skb1)->seq,
4642 TCP_SKB_CB(skb1)->end_seq);
4643 __kfree_skb(skb1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004644 }
4645
4646add_sack:
Ilpo Järvinene60402d2007-08-09 15:14:46 +03004647 if (tcp_is_sack(tp))
Linus Torvalds1da177e2005-04-16 15:20:36 -07004648 tcp_sack_new_ofo_skb(sk, seq, end_seq);
4649 }
4650}
4651
Ilpo Järvinen2cf46632008-08-23 05:11:41 -07004652static struct sk_buff *tcp_collapse_one(struct sock *sk, struct sk_buff *skb,
4653 struct sk_buff_head *list)
4654{
David S. Miller91521942009-05-28 21:35:47 -07004655 struct sk_buff *next = NULL;
4656
4657 if (!skb_queue_is_last(list, skb))
4658 next = skb_queue_next(list, skb);
Ilpo Järvinen2cf46632008-08-23 05:11:41 -07004659
4660 __skb_unlink(skb, list);
4661 __kfree_skb(skb);
4662 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRCVCOLLAPSED);
4663
4664 return next;
4665}
4666
Linus Torvalds1da177e2005-04-16 15:20:36 -07004667/* Collapse contiguous sequence of skbs head..tail with
4668 * sequence numbers start..end.
David S. Miller91521942009-05-28 21:35:47 -07004669 *
4670 * If tail is NULL, this means until the end of the list.
4671 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07004672 * Segments with FIN/SYN are not collapsed (only because this
4673 * simplifies code)
4674 */
4675static void
David S. Miller8728b832005-08-09 19:25:21 -07004676tcp_collapse(struct sock *sk, struct sk_buff_head *list,
4677 struct sk_buff *head, struct sk_buff *tail,
4678 u32 start, u32 end)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004679{
David S. Miller91521942009-05-28 21:35:47 -07004680 struct sk_buff *skb, *n;
4681 bool end_of_skbs;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004682
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -08004683 /* First, check that queue is collapsible and find
Linus Torvalds1da177e2005-04-16 15:20:36 -07004684 * the point where collapsing can be useful. */
David S. Miller91521942009-05-28 21:35:47 -07004685 skb = head;
4686restart:
4687 end_of_skbs = true;
4688 skb_queue_walk_from_safe(list, skb, n) {
4689 if (skb == tail)
4690 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004691 /* No new bits? It is possible on ofo queue. */
4692 if (!before(start, TCP_SKB_CB(skb)->end_seq)) {
Ilpo Järvinen2cf46632008-08-23 05:11:41 -07004693 skb = tcp_collapse_one(sk, skb, list);
David S. Miller91521942009-05-28 21:35:47 -07004694 if (!skb)
4695 break;
4696 goto restart;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004697 }
4698
4699 /* The first skb to collapse is:
4700 * - not SYN/FIN and
4701 * - bloated or contains data before "start" or
4702 * overlaps to the next one.
4703 */
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -07004704 if (!tcp_hdr(skb)->syn && !tcp_hdr(skb)->fin &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07004705 (tcp_win_from_space(skb->truesize) > skb->len ||
David S. Miller91521942009-05-28 21:35:47 -07004706 before(TCP_SKB_CB(skb)->seq, start))) {
4707 end_of_skbs = false;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004708 break;
David S. Miller91521942009-05-28 21:35:47 -07004709 }
4710
4711 if (!skb_queue_is_last(list, skb)) {
4712 struct sk_buff *next = skb_queue_next(list, skb);
4713 if (next != tail &&
4714 TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(next)->seq) {
4715 end_of_skbs = false;
4716 break;
4717 }
4718 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07004719
4720 /* Decided to skip this, advance start seq. */
4721 start = TCP_SKB_CB(skb)->end_seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004722 }
David S. Miller91521942009-05-28 21:35:47 -07004723 if (end_of_skbs || tcp_hdr(skb)->syn || tcp_hdr(skb)->fin)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004724 return;
4725
4726 while (before(start, end)) {
4727 struct sk_buff *nskb;
Chuck Leverc2636b42007-10-23 21:07:32 -07004728 unsigned int header = skb_headroom(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004729 int copy = SKB_MAX_ORDER(header, 0);
4730
4731 /* Too big header? This can happen with IPv6. */
4732 if (copy < 0)
4733 return;
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004734 if (end - start < copy)
4735 copy = end - start;
4736 nskb = alloc_skb(copy + header, GFP_ATOMIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004737 if (!nskb)
4738 return;
Arnaldo Carvalho de Meloc51957d2007-03-10 12:47:22 -03004739
Arnaldo Carvalho de Melo98e399f2007-03-19 15:33:04 -07004740 skb_set_mac_header(nskb, skb_mac_header(skb) - skb->head);
Arnaldo Carvalho de Melo9c702202007-04-25 18:04:18 -07004741 skb_set_network_header(nskb, (skb_network_header(skb) -
4742 skb->head));
4743 skb_set_transport_header(nskb, (skb_transport_header(skb) -
4744 skb->head));
Linus Torvalds1da177e2005-04-16 15:20:36 -07004745 skb_reserve(nskb, header);
4746 memcpy(nskb->head, skb->head, header);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004747 memcpy(nskb->cb, skb->cb, sizeof(skb->cb));
4748 TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(nskb)->end_seq = start;
David S. Miller43f59c82008-09-21 21:28:51 -07004749 __skb_queue_before(list, skb, nskb);
Hideo Aoki3ab224b2007-12-31 00:11:19 -08004750 skb_set_owner_r(nskb, sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004751
4752 /* Copy data, releasing collapsed skbs. */
4753 while (copy > 0) {
4754 int offset = start - TCP_SKB_CB(skb)->seq;
4755 int size = TCP_SKB_CB(skb)->end_seq - start;
4756
Kris Katterjohn09a62662006-01-08 22:24:28 -08004757 BUG_ON(offset < 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004758 if (size > 0) {
4759 size = min(copy, size);
4760 if (skb_copy_bits(skb, offset, skb_put(nskb, size), size))
4761 BUG();
4762 TCP_SKB_CB(nskb)->end_seq += size;
4763 copy -= size;
4764 start += size;
4765 }
4766 if (!before(start, TCP_SKB_CB(skb)->end_seq)) {
Ilpo Järvinen2cf46632008-08-23 05:11:41 -07004767 skb = tcp_collapse_one(sk, skb, list);
David S. Miller91521942009-05-28 21:35:47 -07004768 if (!skb ||
4769 skb == tail ||
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -07004770 tcp_hdr(skb)->syn ||
4771 tcp_hdr(skb)->fin)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004772 return;
4773 }
4774 }
4775 }
4776}
4777
4778/* Collapse ofo queue. Algorithm: select contiguous sequence of skbs
4779 * and tcp_collapse() them until all the queue is collapsed.
4780 */
4781static void tcp_collapse_ofo_queue(struct sock *sk)
4782{
4783 struct tcp_sock *tp = tcp_sk(sk);
4784 struct sk_buff *skb = skb_peek(&tp->out_of_order_queue);
4785 struct sk_buff *head;
4786 u32 start, end;
4787
4788 if (skb == NULL)
4789 return;
4790
4791 start = TCP_SKB_CB(skb)->seq;
4792 end = TCP_SKB_CB(skb)->end_seq;
4793 head = skb;
4794
4795 for (;;) {
David S. Miller91521942009-05-28 21:35:47 -07004796 struct sk_buff *next = NULL;
4797
4798 if (!skb_queue_is_last(&tp->out_of_order_queue, skb))
4799 next = skb_queue_next(&tp->out_of_order_queue, skb);
4800 skb = next;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004801
4802 /* Segment is terminated when we see gap or when
4803 * we are at the end of all the queue. */
David S. Miller91521942009-05-28 21:35:47 -07004804 if (!skb ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07004805 after(TCP_SKB_CB(skb)->seq, end) ||
4806 before(TCP_SKB_CB(skb)->end_seq, start)) {
David S. Miller8728b832005-08-09 19:25:21 -07004807 tcp_collapse(sk, &tp->out_of_order_queue,
4808 head, skb, start, end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004809 head = skb;
David S. Miller91521942009-05-28 21:35:47 -07004810 if (!skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004811 break;
4812 /* Start new segment */
4813 start = TCP_SKB_CB(skb)->seq;
4814 end = TCP_SKB_CB(skb)->end_seq;
4815 } else {
4816 if (before(TCP_SKB_CB(skb)->seq, start))
4817 start = TCP_SKB_CB(skb)->seq;
4818 if (after(TCP_SKB_CB(skb)->end_seq, end))
4819 end = TCP_SKB_CB(skb)->end_seq;
4820 }
4821 }
4822}
4823
Vitaliy Gusevb000cd32008-04-15 00:33:38 -07004824/*
4825 * Purge the out-of-order queue.
Vitaliy Gusev56f367b2008-04-15 20:26:34 -07004826 * Return true if queue was pruned.
Vitaliy Gusevb000cd32008-04-15 00:33:38 -07004827 */
Vitaliy Gusev56f367b2008-04-15 20:26:34 -07004828static int tcp_prune_ofo_queue(struct sock *sk)
Vitaliy Gusevb000cd32008-04-15 00:33:38 -07004829{
4830 struct tcp_sock *tp = tcp_sk(sk);
Vitaliy Gusev56f367b2008-04-15 20:26:34 -07004831 int res = 0;
Vitaliy Gusevb000cd32008-04-15 00:33:38 -07004832
4833 if (!skb_queue_empty(&tp->out_of_order_queue)) {
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07004834 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_OFOPRUNED);
Vitaliy Gusevb000cd32008-04-15 00:33:38 -07004835 __skb_queue_purge(&tp->out_of_order_queue);
4836
4837 /* Reset SACK state. A conforming SACK implementation will
4838 * do the same at a timeout based retransmit. When a connection
4839 * is in a sad state like this, we care only about integrity
4840 * of the connection not performance.
4841 */
4842 if (tp->rx_opt.sack_ok)
4843 tcp_sack_reset(&tp->rx_opt);
4844 sk_mem_reclaim(sk);
Vitaliy Gusev56f367b2008-04-15 20:26:34 -07004845 res = 1;
Vitaliy Gusevb000cd32008-04-15 00:33:38 -07004846 }
Vitaliy Gusev56f367b2008-04-15 20:26:34 -07004847 return res;
Vitaliy Gusevb000cd32008-04-15 00:33:38 -07004848}
4849
Linus Torvalds1da177e2005-04-16 15:20:36 -07004850/* Reduce allocated memory if we can, trying to get
4851 * the socket within its memory limits again.
4852 *
4853 * Return less than zero if we should start dropping frames
4854 * until the socket owning process reads some of the data
4855 * to stabilize the situation.
4856 */
4857static int tcp_prune_queue(struct sock *sk)
4858{
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09004859 struct tcp_sock *tp = tcp_sk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004860
4861 SOCK_DEBUG(sk, "prune_queue: c=%x\n", tp->copied_seq);
4862
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07004863 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PRUNECALLED);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004864
4865 if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07004866 tcp_clamp_window(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004867 else if (tcp_memory_pressure)
4868 tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U * tp->advmss);
4869
4870 tcp_collapse_ofo_queue(sk);
David S. Miller91521942009-05-28 21:35:47 -07004871 if (!skb_queue_empty(&sk->sk_receive_queue))
4872 tcp_collapse(sk, &sk->sk_receive_queue,
4873 skb_peek(&sk->sk_receive_queue),
4874 NULL,
4875 tp->copied_seq, tp->rcv_nxt);
Hideo Aoki3ab224b2007-12-31 00:11:19 -08004876 sk_mem_reclaim(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004877
4878 if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf)
4879 return 0;
4880
4881 /* Collapsing did not help, destructive actions follow.
4882 * This must not ever occur. */
4883
Vitaliy Gusevb000cd32008-04-15 00:33:38 -07004884 tcp_prune_ofo_queue(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004885
4886 if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf)
4887 return 0;
4888
4889 /* If we are really being abused, tell the caller to silently
4890 * drop receive data on the floor. It will get retransmitted
4891 * and hopefully then we'll have sufficient space.
4892 */
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07004893 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_RCVPRUNED);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004894
4895 /* Massive buffer overcommit. */
4896 tp->pred_flags = 0;
4897 return -1;
4898}
4899
Linus Torvalds1da177e2005-04-16 15:20:36 -07004900/* RFC2861, slow part. Adjust cwnd, after it was not full during one rto.
4901 * As additional protections, we do not touch cwnd in retransmission phases,
4902 * and if application hit its sndbuf limit recently.
4903 */
4904void tcp_cwnd_application_limited(struct sock *sk)
4905{
4906 struct tcp_sock *tp = tcp_sk(sk);
4907
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03004908 if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07004909 sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
4910 /* Limited by application or receiver window. */
Ilpo Järvinend254bcd2006-08-04 16:57:42 -07004911 u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk));
4912 u32 win_used = max(tp->snd_cwnd_used, init_win);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004913 if (win_used < tp->snd_cwnd) {
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03004914 tp->snd_ssthresh = tcp_current_ssthresh(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004915 tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1;
4916 }
4917 tp->snd_cwnd_used = 0;
4918 }
4919 tp->snd_cwnd_stamp = tcp_time_stamp;
4920}
4921
Eric Dumazetcf533ea2011-10-21 05:22:42 -04004922static int tcp_should_expand_sndbuf(const struct sock *sk)
David S. Miller0d9901d2005-07-05 15:21:10 -07004923{
Eric Dumazetcf533ea2011-10-21 05:22:42 -04004924 const struct tcp_sock *tp = tcp_sk(sk);
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07004925
David S. Miller0d9901d2005-07-05 15:21:10 -07004926 /* If the user specified a specific send buffer setting, do
4927 * not modify it.
4928 */
4929 if (sk->sk_userlocks & SOCK_SNDBUF_LOCK)
4930 return 0;
4931
4932 /* If we are under global TCP memory pressure, do not expand. */
4933 if (tcp_memory_pressure)
4934 return 0;
4935
4936 /* If we are under soft global TCP memory pressure, do not expand. */
Eric Dumazet8d987e52010-11-09 23:24:26 +00004937 if (atomic_long_read(&tcp_memory_allocated) >= sysctl_tcp_mem[0])
David S. Miller0d9901d2005-07-05 15:21:10 -07004938 return 0;
4939
4940 /* If we filled the congestion window, do not expand. */
4941 if (tp->packets_out >= tp->snd_cwnd)
4942 return 0;
4943
4944 return 1;
4945}
Linus Torvalds1da177e2005-04-16 15:20:36 -07004946
4947/* When incoming ACK allowed to free some skb from write_queue,
4948 * we remember this event in flag SOCK_QUEUE_SHRUNK and wake up socket
4949 * on the exit from tcp input handler.
4950 *
4951 * PROBLEM: sndbuf expansion does not work well with largesend.
4952 */
4953static void tcp_new_space(struct sock *sk)
4954{
4955 struct tcp_sock *tp = tcp_sk(sk);
4956
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07004957 if (tcp_should_expand_sndbuf(sk)) {
Eric Dumazet87fb4b72011-10-13 07:28:54 +00004958 int sndmem = SKB_TRUESIZE(max_t(u32,
4959 tp->rx_opt.mss_clamp,
4960 tp->mss_cache) +
4961 MAX_TCP_HEADER);
Ilpo Järvinen4a7e5602008-10-07 14:43:31 -07004962 int demanded = max_t(unsigned int, tp->snd_cwnd,
Ilpo Järvinen056834d2007-12-31 14:57:14 -08004963 tp->reordering + 1);
4964 sndmem *= 2 * demanded;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004965 if (sndmem > sk->sk_sndbuf)
4966 sk->sk_sndbuf = min(sndmem, sysctl_tcp_wmem[2]);
4967 tp->snd_cwnd_stamp = tcp_time_stamp;
4968 }
4969
4970 sk->sk_write_space(sk);
4971}
4972
Stephen Hemminger40efc6f2006-01-03 16:03:49 -08004973static void tcp_check_space(struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004974{
4975 if (sock_flag(sk, SOCK_QUEUE_SHRUNK)) {
4976 sock_reset_flag(sk, SOCK_QUEUE_SHRUNK);
4977 if (sk->sk_socket &&
4978 test_bit(SOCK_NOSPACE, &sk->sk_socket->flags))
4979 tcp_new_space(sk);
4980 }
4981}
4982
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07004983static inline void tcp_data_snd_check(struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004984{
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07004985 tcp_push_pending_frames(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004986 tcp_check_space(sk);
4987}
4988
4989/*
4990 * Check if sending an ack is needed.
4991 */
4992static void __tcp_ack_snd_check(struct sock *sk, int ofo_possible)
4993{
4994 struct tcp_sock *tp = tcp_sk(sk);
4995
4996 /* More than one full frame received... */
Joe Perches9d4fb272009-11-23 10:41:23 -08004997 if (((tp->rcv_nxt - tp->rcv_wup) > inet_csk(sk)->icsk_ack.rcv_mss &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07004998 /* ... and right edge of window advances far enough.
4999 * (tcp_recvmsg() will send ACK otherwise). Or...
5000 */
Joe Perches9d4fb272009-11-23 10:41:23 -08005001 __tcp_select_window(sk) >= tp->rcv_wnd) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07005002 /* We ACK each frame or... */
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07005003 tcp_in_quickack_mode(sk) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07005004 /* We have out of order data. */
Ilpo Järvinen056834d2007-12-31 14:57:14 -08005005 (ofo_possible && skb_peek(&tp->out_of_order_queue))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07005006 /* Then ack it now */
5007 tcp_send_ack(sk);
5008 } else {
5009 /* Else, send delayed ack. */
5010 tcp_send_delayed_ack(sk);
5011 }
5012}
5013
Stephen Hemminger40efc6f2006-01-03 16:03:49 -08005014static inline void tcp_ack_snd_check(struct sock *sk)
Linus Torvalds1da177e2005-04-16 15:20:36 -07005015{
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07005016 if (!inet_csk_ack_scheduled(sk)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07005017 /* We sent a data segment already. */
5018 return;
5019 }
5020 __tcp_ack_snd_check(sk, 1);
5021}
5022
5023/*
5024 * This routine is only called when we have urgent data
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -08005025 * signaled. Its the 'slow' part of tcp_urg. It could be
Linus Torvalds1da177e2005-04-16 15:20:36 -07005026 * moved inline now as tcp_urg is only called from one
5027 * place. We handle URGent data wrong. We have to - as
5028 * BSD still doesn't use the correction from RFC961.
5029 * For 1003.1g we should support a new option TCP_STDURG to permit
5030 * either form (or just set the sysctl tcp_stdurg).
5031 */
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005032
Eric Dumazetcf533ea2011-10-21 05:22:42 -04005033static void tcp_check_urg(struct sock *sk, const struct tcphdr *th)
Linus Torvalds1da177e2005-04-16 15:20:36 -07005034{
5035 struct tcp_sock *tp = tcp_sk(sk);
5036 u32 ptr = ntohs(th->urg_ptr);
5037
5038 if (ptr && !sysctl_tcp_stdurg)
5039 ptr--;
5040 ptr += ntohl(th->seq);
5041
5042 /* Ignore urgent data that we've already seen and read. */
5043 if (after(tp->copied_seq, ptr))
5044 return;
5045
5046 /* Do not replay urg ptr.
5047 *
5048 * NOTE: interesting situation not covered by specs.
5049 * Misbehaving sender may send urg ptr, pointing to segment,
5050 * which we already have in ofo queue. We are not able to fetch
5051 * such data and will stay in TCP_URG_NOTYET until will be eaten
5052 * by recvmsg(). Seems, we are not obliged to handle such wicked
5053 * situations. But it is worth to think about possibility of some
5054 * DoSes using some hypothetical application level deadlock.
5055 */
5056 if (before(ptr, tp->rcv_nxt))
5057 return;
5058
5059 /* Do we already have a newer (or duplicate) urgent pointer? */
5060 if (tp->urg_data && !after(ptr, tp->urg_seq))
5061 return;
5062
5063 /* Tell the world about our new urgent pointer. */
5064 sk_send_sigurg(sk);
5065
5066 /* We may be adding urgent data when the last byte read was
5067 * urgent. To do this requires some care. We cannot just ignore
5068 * tp->copied_seq since we would read the last urgent byte again
5069 * as data, nor can we alter copied_seq until this data arrives
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -08005070 * or we break the semantics of SIOCATMARK (and thus sockatmark())
Linus Torvalds1da177e2005-04-16 15:20:36 -07005071 *
5072 * NOTE. Double Dutch. Rendering to plain English: author of comment
5073 * above did something sort of send("A", MSG_OOB); send("B", MSG_OOB);
5074 * and expect that both A and B disappear from stream. This is _wrong_.
5075 * Though this happens in BSD with high probability, this is occasional.
5076 * Any application relying on this is buggy. Note also, that fix "works"
5077 * only in this artificial test. Insert some normal data between A and B and we will
5078 * decline of BSD again. Verdict: it is better to remove to trap
5079 * buggy users.
5080 */
5081 if (tp->urg_seq == tp->copied_seq && tp->urg_data &&
Ilpo Järvinen056834d2007-12-31 14:57:14 -08005082 !sock_flag(sk, SOCK_URGINLINE) && tp->copied_seq != tp->rcv_nxt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07005083 struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
5084 tp->copied_seq++;
5085 if (skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq)) {
David S. Miller8728b832005-08-09 19:25:21 -07005086 __skb_unlink(skb, &sk->sk_receive_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005087 __kfree_skb(skb);
5088 }
5089 }
5090
Ilpo Järvinen056834d2007-12-31 14:57:14 -08005091 tp->urg_data = TCP_URG_NOTYET;
5092 tp->urg_seq = ptr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07005093
5094 /* Disable header prediction. */
5095 tp->pred_flags = 0;
5096}
5097
5098/* This is the 'fast' part of urgent handling. */
Eric Dumazetcf533ea2011-10-21 05:22:42 -04005099static void tcp_urg(struct sock *sk, struct sk_buff *skb, const struct tcphdr *th)
Linus Torvalds1da177e2005-04-16 15:20:36 -07005100{
5101 struct tcp_sock *tp = tcp_sk(sk);
5102
5103 /* Check if we get a new urgent pointer - normally not. */
5104 if (th->urg)
Ilpo Järvinen056834d2007-12-31 14:57:14 -08005105 tcp_check_urg(sk, th);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005106
5107 /* Do we wait for any urgent data? - normally not... */
5108 if (tp->urg_data == TCP_URG_NOTYET) {
5109 u32 ptr = tp->urg_seq - ntohl(th->seq) + (th->doff * 4) -
5110 th->syn;
5111
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005112 /* Is the urgent pointer pointing into this packet? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07005113 if (ptr < skb->len) {
5114 u8 tmp;
5115 if (skb_copy_bits(skb, ptr, &tmp, 1))
5116 BUG();
5117 tp->urg_data = TCP_URG_VALID | tmp;
5118 if (!sock_flag(sk, SOCK_DEAD))
5119 sk->sk_data_ready(sk, 0);
5120 }
5121 }
5122}
5123
5124static int tcp_copy_to_iovec(struct sock *sk, struct sk_buff *skb, int hlen)
5125{
5126 struct tcp_sock *tp = tcp_sk(sk);
5127 int chunk = skb->len - hlen;
5128 int err;
5129
5130 local_bh_enable();
Herbert Xu60476372007-04-09 11:59:39 -07005131 if (skb_csum_unnecessary(skb))
Linus Torvalds1da177e2005-04-16 15:20:36 -07005132 err = skb_copy_datagram_iovec(skb, hlen, tp->ucopy.iov, chunk);
5133 else
5134 err = skb_copy_and_csum_datagram_iovec(skb, hlen,
5135 tp->ucopy.iov);
5136
5137 if (!err) {
5138 tp->ucopy.len -= chunk;
5139 tp->copied_seq += chunk;
5140 tcp_rcv_space_adjust(sk);
5141 }
5142
5143 local_bh_disable();
5144 return err;
5145}
5146
Ilpo Järvinen056834d2007-12-31 14:57:14 -08005147static __sum16 __tcp_checksum_complete_user(struct sock *sk,
5148 struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -07005149{
Al Virob51655b2006-11-14 21:40:42 -08005150 __sum16 result;
Linus Torvalds1da177e2005-04-16 15:20:36 -07005151
5152 if (sock_owned_by_user(sk)) {
5153 local_bh_enable();
5154 result = __tcp_checksum_complete(skb);
5155 local_bh_disable();
5156 } else {
5157 result = __tcp_checksum_complete(skb);
5158 }
5159 return result;
5160}
5161
Ilpo Järvinen056834d2007-12-31 14:57:14 -08005162static inline int tcp_checksum_complete_user(struct sock *sk,
5163 struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -07005164{
Herbert Xu60476372007-04-09 11:59:39 -07005165 return !skb_csum_unnecessary(skb) &&
Ilpo Järvinen056834d2007-12-31 14:57:14 -08005166 __tcp_checksum_complete_user(sk, skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005167}
5168
Chris Leech1a2449a2006-05-23 18:05:53 -07005169#ifdef CONFIG_NET_DMA
Ilpo Järvinen056834d2007-12-31 14:57:14 -08005170static int tcp_dma_try_early_copy(struct sock *sk, struct sk_buff *skb,
5171 int hlen)
Chris Leech1a2449a2006-05-23 18:05:53 -07005172{
5173 struct tcp_sock *tp = tcp_sk(sk);
5174 int chunk = skb->len - hlen;
5175 int dma_cookie;
5176 int copied_early = 0;
5177
5178 if (tp->ucopy.wakeup)
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005179 return 0;
Chris Leech1a2449a2006-05-23 18:05:53 -07005180
5181 if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
Dan Williamsf67b4592009-01-06 11:38:15 -07005182 tp->ucopy.dma_chan = dma_find_channel(DMA_MEMCPY);
Chris Leech1a2449a2006-05-23 18:05:53 -07005183
Herbert Xu60476372007-04-09 11:59:39 -07005184 if (tp->ucopy.dma_chan && skb_csum_unnecessary(skb)) {
Chris Leech1a2449a2006-05-23 18:05:53 -07005185
5186 dma_cookie = dma_skb_copy_datagram_iovec(tp->ucopy.dma_chan,
Ilpo Järvinen056834d2007-12-31 14:57:14 -08005187 skb, hlen,
5188 tp->ucopy.iov, chunk,
5189 tp->ucopy.pinned_list);
Chris Leech1a2449a2006-05-23 18:05:53 -07005190
5191 if (dma_cookie < 0)
5192 goto out;
5193
5194 tp->ucopy.dma_cookie = dma_cookie;
5195 copied_early = 1;
5196
5197 tp->ucopy.len -= chunk;
5198 tp->copied_seq += chunk;
5199 tcp_rcv_space_adjust(sk);
5200
5201 if ((tp->ucopy.len == 0) ||
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -07005202 (tcp_flag_word(tcp_hdr(skb)) & TCP_FLAG_PSH) ||
Chris Leech1a2449a2006-05-23 18:05:53 -07005203 (atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1))) {
5204 tp->ucopy.wakeup = 1;
5205 sk->sk_data_ready(sk, 0);
5206 }
5207 } else if (chunk > 0) {
5208 tp->ucopy.wakeup = 1;
5209 sk->sk_data_ready(sk, 0);
5210 }
5211out:
5212 return copied_early;
5213}
5214#endif /* CONFIG_NET_DMA */
5215
Ilpo Järvinencbe2d122008-08-23 05:10:12 -07005216/* Does PAWS and seqno based validation of an incoming segment, flags will
5217 * play significant role here.
5218 */
5219static int tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
Eric Dumazetcf533ea2011-10-21 05:22:42 -04005220 const struct tcphdr *th, int syn_inerr)
Ilpo Järvinencbe2d122008-08-23 05:10:12 -07005221{
Eric Dumazetcf533ea2011-10-21 05:22:42 -04005222 const u8 *hash_location;
Ilpo Järvinencbe2d122008-08-23 05:10:12 -07005223 struct tcp_sock *tp = tcp_sk(sk);
5224
5225 /* RFC1323: H1. Apply PAWS check first. */
William Allen Simpson4957faade2009-12-02 18:25:27 +00005226 if (tcp_fast_parse_options(skb, th, tp, &hash_location) &&
5227 tp->rx_opt.saw_tstamp &&
Ilpo Järvinencbe2d122008-08-23 05:10:12 -07005228 tcp_paws_discard(sk, skb)) {
5229 if (!th->rst) {
5230 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSESTABREJECTED);
5231 tcp_send_dupack(sk, skb);
5232 goto discard;
5233 }
5234 /* Reset is accepted even if it did not pass PAWS. */
5235 }
5236
5237 /* Step 1: check sequence number */
5238 if (!tcp_sequence(tp, TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq)) {
5239 /* RFC793, page 37: "In all states except SYN-SENT, all reset
5240 * (RST) segments are validated by checking their SEQ-fields."
5241 * And page 69: "If an incoming segment is not acceptable,
5242 * an acknowledgment should be sent in reply (unless the RST
5243 * bit is set, if so drop the segment and return)".
5244 */
5245 if (!th->rst)
5246 tcp_send_dupack(sk, skb);
5247 goto discard;
5248 }
5249
5250 /* Step 2: check RST bit */
5251 if (th->rst) {
5252 tcp_reset(sk);
5253 goto discard;
5254 }
5255
5256 /* ts_recent update must be made after we are sure that the packet
5257 * is in window.
5258 */
5259 tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq);
5260
5261 /* step 3: check security and precedence [ignored] */
5262
5263 /* step 4: Check for a SYN in window. */
5264 if (th->syn && !before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) {
5265 if (syn_inerr)
5266 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
5267 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONSYN);
5268 tcp_reset(sk);
5269 return -1;
5270 }
5271
5272 return 1;
5273
5274discard:
5275 __kfree_skb(skb);
5276 return 0;
5277}
5278
Linus Torvalds1da177e2005-04-16 15:20:36 -07005279/*
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005280 * TCP receive function for the ESTABLISHED state.
Linus Torvalds1da177e2005-04-16 15:20:36 -07005281 *
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005282 * It is split into a fast path and a slow path. The fast path is
Linus Torvalds1da177e2005-04-16 15:20:36 -07005283 * disabled when:
5284 * - A zero window was announced from us - zero window probing
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005285 * is only handled properly in the slow path.
Linus Torvalds1da177e2005-04-16 15:20:36 -07005286 * - Out of order segments arrived.
5287 * - Urgent data is expected.
5288 * - There is no buffer space left
5289 * - Unexpected TCP flags/window values/header lengths are received
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005290 * (detected by checking the TCP header against pred_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07005291 * - Data is sent in both directions. Fast path only supports pure senders
5292 * or pure receivers (this means either the sequence number or the ack
5293 * value must stay constant)
5294 * - Unexpected TCP option.
5295 *
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005296 * When these conditions are not satisfied it drops into a standard
Linus Torvalds1da177e2005-04-16 15:20:36 -07005297 * receive procedure patterned after RFC793 to handle all cases.
5298 * The first three cases are guaranteed by proper pred_flags setting,
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005299 * the rest is checked inline. Fast processing is turned on in
Linus Torvalds1da177e2005-04-16 15:20:36 -07005300 * tcp_data_queue when everything is OK.
5301 */
5302int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
Eric Dumazetcf533ea2011-10-21 05:22:42 -04005303 const struct tcphdr *th, unsigned int len)
Linus Torvalds1da177e2005-04-16 15:20:36 -07005304{
5305 struct tcp_sock *tp = tcp_sk(sk);
Ilpo Järvinencbe2d122008-08-23 05:10:12 -07005306 int res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07005307
5308 /*
5309 * Header prediction.
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005310 * The code loosely follows the one in the famous
Linus Torvalds1da177e2005-04-16 15:20:36 -07005311 * "30 instruction TCP receive" Van Jacobson mail.
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005312 *
5313 * Van's trick is to deposit buffers into socket queue
Linus Torvalds1da177e2005-04-16 15:20:36 -07005314 * on a device interrupt, to call tcp_recv function
5315 * on the receive process context and checksum and copy
5316 * the buffer to user space. smart...
5317 *
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005318 * Our current scheme is not silly either but we take the
Linus Torvalds1da177e2005-04-16 15:20:36 -07005319 * extra cost of the net_bh soft interrupt processing...
5320 * We do checksum and copy also but from device to kernel.
5321 */
5322
5323 tp->rx_opt.saw_tstamp = 0;
5324
5325 /* pred_flags is 0xS?10 << 16 + snd_wnd
Stephen Hemmingercaa20d9a2005-11-10 17:13:47 -08005326 * if header_prediction is to be made
Linus Torvalds1da177e2005-04-16 15:20:36 -07005327 * 'S' will always be tp->tcp_header_len >> 2
5328 * '?' will be 0 for the fast path, otherwise pred_flags is 0 to
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005329 * turn it off (when there are holes in the receive
Linus Torvalds1da177e2005-04-16 15:20:36 -07005330 * space for instance)
5331 * PSH flag is ignored.
5332 */
5333
5334 if ((tcp_flag_word(th) & TCP_HP_BITS) == tp->pred_flags &&
John Dykstra96e0bf42009-03-22 21:49:57 -07005335 TCP_SKB_CB(skb)->seq == tp->rcv_nxt &&
5336 !after(TCP_SKB_CB(skb)->ack_seq, tp->snd_nxt)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07005337 int tcp_header_len = tp->tcp_header_len;
5338
5339 /* Timestamp header prediction: tcp_header_len
5340 * is automatically equal to th->doff*4 due to pred_flags
5341 * match.
5342 */
5343
5344 /* Check timestamp */
5345 if (tcp_header_len == sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07005346 /* No? Slow path! */
Ilpo Järvinena4356b22008-08-23 05:12:29 -07005347 if (!tcp_parse_aligned_timestamp(tp, th))
Linus Torvalds1da177e2005-04-16 15:20:36 -07005348 goto slow_path;
5349
Linus Torvalds1da177e2005-04-16 15:20:36 -07005350 /* If PAWS failed, check it more carefully in slow path */
5351 if ((s32)(tp->rx_opt.rcv_tsval - tp->rx_opt.ts_recent) < 0)
5352 goto slow_path;
5353
5354 /* DO NOT update ts_recent here, if checksum fails
5355 * and timestamp was corrupted part, it will result
5356 * in a hung connection since we will drop all
5357 * future packets due to the PAWS test.
5358 */
5359 }
5360
5361 if (len <= tcp_header_len) {
5362 /* Bulk data transfer: sender */
5363 if (len == tcp_header_len) {
5364 /* Predicted packet is in window by definition.
5365 * seq == rcv_nxt and rcv_wup <= rcv_nxt.
5366 * Hence, check seq<=rcv_wup reduces to:
5367 */
5368 if (tcp_header_len ==
5369 (sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) &&
5370 tp->rcv_nxt == tp->rcv_wup)
5371 tcp_store_ts_recent(tp);
5372
Linus Torvalds1da177e2005-04-16 15:20:36 -07005373 /* We know that such packets are checksummed
5374 * on entry.
5375 */
5376 tcp_ack(sk, skb, 0);
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005377 __kfree_skb(skb);
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07005378 tcp_data_snd_check(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005379 return 0;
5380 } else { /* Header too small */
Pavel Emelyanov63231bd2008-07-16 20:22:25 -07005381 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005382 goto discard;
5383 }
5384 } else {
5385 int eaten = 0;
Chris Leech1a2449a2006-05-23 18:05:53 -07005386 int copied_early = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07005387
Chris Leech1a2449a2006-05-23 18:05:53 -07005388 if (tp->copied_seq == tp->rcv_nxt &&
5389 len - tcp_header_len <= tp->ucopy.len) {
5390#ifdef CONFIG_NET_DMA
5391 if (tcp_dma_try_early_copy(sk, skb, tcp_header_len)) {
5392 copied_early = 1;
5393 eaten = 1;
5394 }
5395#endif
Ilpo Järvinen056834d2007-12-31 14:57:14 -08005396 if (tp->ucopy.task == current &&
5397 sock_owned_by_user(sk) && !copied_early) {
Chris Leech1a2449a2006-05-23 18:05:53 -07005398 __set_current_state(TASK_RUNNING);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005399
Chris Leech1a2449a2006-05-23 18:05:53 -07005400 if (!tcp_copy_to_iovec(sk, skb, tcp_header_len))
5401 eaten = 1;
5402 }
5403 if (eaten) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07005404 /* Predicted packet is in window by definition.
5405 * seq == rcv_nxt and rcv_wup <= rcv_nxt.
5406 * Hence, check seq<=rcv_wup reduces to:
5407 */
5408 if (tcp_header_len ==
5409 (sizeof(struct tcphdr) +
5410 TCPOLEN_TSTAMP_ALIGNED) &&
5411 tp->rcv_nxt == tp->rcv_wup)
5412 tcp_store_ts_recent(tp);
5413
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07005414 tcp_rcv_rtt_measure_ts(sk, skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005415
5416 __skb_pull(skb, tcp_header_len);
5417 tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07005418 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPHPHITSTOUSER);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005419 }
Chris Leech1a2449a2006-05-23 18:05:53 -07005420 if (copied_early)
5421 tcp_cleanup_rbuf(sk, skb->len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005422 }
5423 if (!eaten) {
5424 if (tcp_checksum_complete_user(sk, skb))
5425 goto csum_error;
5426
5427 /* Predicted packet is in window by definition.
5428 * seq == rcv_nxt and rcv_wup <= rcv_nxt.
5429 * Hence, check seq<=rcv_wup reduces to:
5430 */
5431 if (tcp_header_len ==
5432 (sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) &&
5433 tp->rcv_nxt == tp->rcv_wup)
5434 tcp_store_ts_recent(tp);
5435
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07005436 tcp_rcv_rtt_measure_ts(sk, skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005437
5438 if ((int)skb->truesize > sk->sk_forward_alloc)
5439 goto step5;
5440
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07005441 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPHPHITS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005442
5443 /* Bulk data transfer: receiver */
Ilpo Järvinen056834d2007-12-31 14:57:14 -08005444 __skb_pull(skb, tcp_header_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005445 __skb_queue_tail(&sk->sk_receive_queue, skb);
Hideo Aoki3ab224b2007-12-31 00:11:19 -08005446 skb_set_owner_r(skb, sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005447 tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
5448 }
5449
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07005450 tcp_event_data_recv(sk, skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005451
5452 if (TCP_SKB_CB(skb)->ack_seq != tp->snd_una) {
5453 /* Well, only one small jumplet in fast path... */
5454 tcp_ack(sk, skb, FLAG_DATA);
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07005455 tcp_data_snd_check(sk);
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07005456 if (!inet_csk_ack_scheduled(sk))
Linus Torvalds1da177e2005-04-16 15:20:36 -07005457 goto no_ack;
5458 }
5459
Ali Saidi53240c22008-10-07 15:31:19 -07005460 if (!copied_early || tp->rcv_nxt != tp->rcv_wup)
5461 __tcp_ack_snd_check(sk, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005462no_ack:
Chris Leech1a2449a2006-05-23 18:05:53 -07005463#ifdef CONFIG_NET_DMA
5464 if (copied_early)
5465 __skb_queue_tail(&sk->sk_async_wait_queue, skb);
5466 else
5467#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07005468 if (eaten)
5469 __kfree_skb(skb);
5470 else
5471 sk->sk_data_ready(sk, 0);
5472 return 0;
5473 }
5474 }
5475
5476slow_path:
Ilpo Järvinen056834d2007-12-31 14:57:14 -08005477 if (len < (th->doff << 2) || tcp_checksum_complete_user(sk, skb))
Linus Torvalds1da177e2005-04-16 15:20:36 -07005478 goto csum_error;
5479
5480 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07005481 * Standard slow path.
5482 */
5483
Ilpo Järvinencbe2d122008-08-23 05:10:12 -07005484 res = tcp_validate_incoming(sk, skb, th, 1);
5485 if (res <= 0)
5486 return -res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07005487
5488step5:
John Dykstra96e0bf42009-03-22 21:49:57 -07005489 if (th->ack && tcp_ack(sk, skb, FLAG_SLOWPATH) < 0)
5490 goto discard;
Linus Torvalds1da177e2005-04-16 15:20:36 -07005491
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07005492 tcp_rcv_rtt_measure_ts(sk, skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005493
5494 /* Process urgent data. */
5495 tcp_urg(sk, skb, th);
5496
5497 /* step 7: process the segment text */
5498 tcp_data_queue(sk, skb);
5499
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07005500 tcp_data_snd_check(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005501 tcp_ack_snd_check(sk);
5502 return 0;
5503
5504csum_error:
Pavel Emelyanov63231bd2008-07-16 20:22:25 -07005505 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005506
5507discard:
5508 __kfree_skb(skb);
5509 return 0;
5510}
Eric Dumazet4bc2f182010-07-09 21:22:10 +00005511EXPORT_SYMBOL(tcp_rcv_established);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005512
5513static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
Eric Dumazetcf533ea2011-10-21 05:22:42 -04005514 const struct tcphdr *th, unsigned int len)
Linus Torvalds1da177e2005-04-16 15:20:36 -07005515{
Eric Dumazetcf533ea2011-10-21 05:22:42 -04005516 const u8 *hash_location;
Arnaldo Carvalho de Melod83d8462005-12-13 23:26:10 -08005517 struct inet_connection_sock *icsk = inet_csk(sk);
William Allen Simpson4957faade2009-12-02 18:25:27 +00005518 struct tcp_sock *tp = tcp_sk(sk);
William Allen Simpson4957faade2009-12-02 18:25:27 +00005519 struct tcp_cookie_values *cvp = tp->cookie_values;
5520 int saved_clamp = tp->rx_opt.mss_clamp;
Linus Torvalds1da177e2005-04-16 15:20:36 -07005521
David S. Millerbb5b7c12009-12-15 20:56:42 -08005522 tcp_parse_options(skb, &tp->rx_opt, &hash_location, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005523
5524 if (th->ack) {
5525 /* rfc793:
5526 * "If the state is SYN-SENT then
5527 * first check the ACK bit
5528 * If the ACK bit is set
5529 * If SEG.ACK =< ISS, or SEG.ACK > SND.NXT, send
5530 * a reset (unless the RST bit is set, if so drop
5531 * the segment and return)"
5532 *
5533 * We do not send data with SYN, so that RFC-correct
5534 * test reduces to:
5535 */
5536 if (TCP_SKB_CB(skb)->ack_seq != tp->snd_nxt)
5537 goto reset_and_undo;
5538
5539 if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
5540 !between(tp->rx_opt.rcv_tsecr, tp->retrans_stamp,
5541 tcp_time_stamp)) {
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07005542 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSACTIVEREJECTED);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005543 goto reset_and_undo;
5544 }
5545
5546 /* Now ACK is acceptable.
5547 *
5548 * "If the RST bit is set
5549 * If the ACK was acceptable then signal the user "error:
5550 * connection reset", drop the segment, enter CLOSED state,
5551 * delete TCB, and return."
5552 */
5553
5554 if (th->rst) {
5555 tcp_reset(sk);
5556 goto discard;
5557 }
5558
5559 /* rfc793:
5560 * "fifth, if neither of the SYN or RST bits is set then
5561 * drop the segment and return."
5562 *
5563 * See note below!
5564 * --ANK(990513)
5565 */
5566 if (!th->syn)
5567 goto discard_and_undo;
5568
5569 /* rfc793:
5570 * "If the SYN bit is on ...
5571 * are acceptable then ...
5572 * (our SYN has been ACKed), change the connection
5573 * state to ESTABLISHED..."
5574 */
5575
5576 TCP_ECN_rcv_synack(tp, th);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005577
5578 tp->snd_wl1 = TCP_SKB_CB(skb)->seq;
5579 tcp_ack(sk, skb, FLAG_SLOWPATH);
5580
5581 /* Ok.. it's good. Set up sequence numbers and
5582 * move to established.
5583 */
5584 tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
5585 tp->rcv_wup = TCP_SKB_CB(skb)->seq + 1;
5586
5587 /* RFC1323: The window in SYN & SYN/ACK segments is
5588 * never scaled.
5589 */
5590 tp->snd_wnd = ntohs(th->window);
Hantzis Fotisee7537b2009-03-02 22:42:02 -08005591 tcp_init_wl(tp, TCP_SKB_CB(skb)->seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005592
5593 if (!tp->rx_opt.wscale_ok) {
5594 tp->rx_opt.snd_wscale = tp->rx_opt.rcv_wscale = 0;
5595 tp->window_clamp = min(tp->window_clamp, 65535U);
5596 }
5597
5598 if (tp->rx_opt.saw_tstamp) {
5599 tp->rx_opt.tstamp_ok = 1;
5600 tp->tcp_header_len =
5601 sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED;
5602 tp->advmss -= TCPOLEN_TSTAMP_ALIGNED;
5603 tcp_store_ts_recent(tp);
5604 } else {
5605 tp->tcp_header_len = sizeof(struct tcphdr);
5606 }
5607
Ilpo Järvinene60402d2007-08-09 15:14:46 +03005608 if (tcp_is_sack(tp) && sysctl_tcp_fack)
5609 tcp_enable_fack(tp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005610
John Heffner5d424d52006-03-20 17:53:41 -08005611 tcp_mtup_init(sk);
Arnaldo Carvalho de Melod83d8462005-12-13 23:26:10 -08005612 tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005613 tcp_initialize_rcv_mss(sk);
5614
5615 /* Remember, tcp_poll() does not lock socket!
5616 * Change state from SYN-SENT only after copied_seq
5617 * is initialized. */
5618 tp->copied_seq = tp->rcv_nxt;
William Allen Simpson4957faade2009-12-02 18:25:27 +00005619
5620 if (cvp != NULL &&
5621 cvp->cookie_pair_size > 0 &&
5622 tp->rx_opt.cookie_plus > 0) {
5623 int cookie_size = tp->rx_opt.cookie_plus
5624 - TCPOLEN_COOKIE_BASE;
5625 int cookie_pair_size = cookie_size
5626 + cvp->cookie_desired;
5627
5628 /* A cookie extension option was sent and returned.
5629 * Note that each incoming SYNACK replaces the
5630 * Responder cookie. The initial exchange is most
5631 * fragile, as protection against spoofing relies
5632 * entirely upon the sequence and timestamp (above).
5633 * This replacement strategy allows the correct pair to
5634 * pass through, while any others will be filtered via
5635 * Responder verification later.
5636 */
5637 if (sizeof(cvp->cookie_pair) >= cookie_pair_size) {
5638 memcpy(&cvp->cookie_pair[cvp->cookie_desired],
5639 hash_location, cookie_size);
5640 cvp->cookie_pair_size = cookie_pair_size;
5641 }
5642 }
5643
Ralf Baechlee16aa202006-12-07 00:11:33 -08005644 smp_mb();
Linus Torvalds1da177e2005-04-16 15:20:36 -07005645 tcp_set_state(sk, TCP_ESTABLISHED);
5646
Venkat Yekkirala6b877692006-11-08 17:04:09 -06005647 security_inet_conn_established(sk, skb);
5648
Linus Torvalds1da177e2005-04-16 15:20:36 -07005649 /* Make sure socket is routed, for correct metrics. */
Arnaldo Carvalho de Melo8292a172005-12-13 23:15:52 -08005650 icsk->icsk_af_ops->rebuild_header(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005651
5652 tcp_init_metrics(sk);
5653
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03005654 tcp_init_congestion_control(sk);
Stephen Hemminger317a76f2005-06-23 12:19:55 -07005655
Linus Torvalds1da177e2005-04-16 15:20:36 -07005656 /* Prevent spurious tcp_cwnd_restart() on first data
5657 * packet.
5658 */
5659 tp->lsndtime = tcp_time_stamp;
5660
5661 tcp_init_buffer_space(sk);
5662
5663 if (sock_flag(sk, SOCK_KEEPOPEN))
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07005664 inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tp));
Linus Torvalds1da177e2005-04-16 15:20:36 -07005665
5666 if (!tp->rx_opt.snd_wscale)
5667 __tcp_fast_path_on(tp, tp->snd_wnd);
5668 else
5669 tp->pred_flags = 0;
5670
5671 if (!sock_flag(sk, SOCK_DEAD)) {
5672 sk->sk_state_change(sk);
Pavel Emelyanov8d8ad9d2007-11-26 20:10:50 +08005673 sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005674 }
5675
Arnaldo Carvalho de Melo295f7322005-08-09 20:11:56 -07005676 if (sk->sk_write_pending ||
5677 icsk->icsk_accept_queue.rskq_defer_accept ||
5678 icsk->icsk_ack.pingpong) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07005679 /* Save one ACK. Data will be ready after
5680 * several ticks, if write_pending is set.
5681 *
5682 * It may be deleted, but with this feature tcpdumps
5683 * look so _wonderfully_ clever, that I was not able
5684 * to stand against the temptation 8) --ANK
5685 */
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07005686 inet_csk_schedule_ack(sk);
Arnaldo Carvalho de Melo295f7322005-08-09 20:11:56 -07005687 icsk->icsk_ack.lrcvtime = tcp_time_stamp;
5688 icsk->icsk_ack.ato = TCP_ATO_MIN;
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07005689 tcp_incr_quickack(sk);
5690 tcp_enter_quickack_mode(sk);
Arnaldo Carvalho de Melo3f421ba2005-08-09 20:11:08 -07005691 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
5692 TCP_DELACK_MAX, TCP_RTO_MAX);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005693
5694discard:
5695 __kfree_skb(skb);
5696 return 0;
5697 } else {
5698 tcp_send_ack(sk);
5699 }
5700 return -1;
5701 }
5702
5703 /* No ACK in the segment */
5704
5705 if (th->rst) {
5706 /* rfc793:
5707 * "If the RST bit is set
5708 *
5709 * Otherwise (no ACK) drop the segment and return."
5710 */
5711
5712 goto discard_and_undo;
5713 }
5714
5715 /* PAWS check. */
Ilpo Järvinen056834d2007-12-31 14:57:14 -08005716 if (tp->rx_opt.ts_recent_stamp && tp->rx_opt.saw_tstamp &&
Ilpo Järvinenc887e6d2009-03-14 14:23:03 +00005717 tcp_paws_reject(&tp->rx_opt, 0))
Linus Torvalds1da177e2005-04-16 15:20:36 -07005718 goto discard_and_undo;
5719
5720 if (th->syn) {
5721 /* We see SYN without ACK. It is attempt of
5722 * simultaneous connect with crossed SYNs.
5723 * Particularly, it can be connect to self.
5724 */
5725 tcp_set_state(sk, TCP_SYN_RECV);
5726
5727 if (tp->rx_opt.saw_tstamp) {
5728 tp->rx_opt.tstamp_ok = 1;
5729 tcp_store_ts_recent(tp);
5730 tp->tcp_header_len =
5731 sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED;
5732 } else {
5733 tp->tcp_header_len = sizeof(struct tcphdr);
5734 }
5735
5736 tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
5737 tp->rcv_wup = TCP_SKB_CB(skb)->seq + 1;
5738
5739 /* RFC1323: The window in SYN & SYN/ACK segments is
5740 * never scaled.
5741 */
5742 tp->snd_wnd = ntohs(th->window);
5743 tp->snd_wl1 = TCP_SKB_CB(skb)->seq;
5744 tp->max_window = tp->snd_wnd;
5745
5746 TCP_ECN_rcv_syn(tp, th);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005747
John Heffner5d424d52006-03-20 17:53:41 -08005748 tcp_mtup_init(sk);
Arnaldo Carvalho de Melod83d8462005-12-13 23:26:10 -08005749 tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005750 tcp_initialize_rcv_mss(sk);
5751
Linus Torvalds1da177e2005-04-16 15:20:36 -07005752 tcp_send_synack(sk);
5753#if 0
5754 /* Note, we could accept data and URG from this segment.
5755 * There are no obstacles to make this.
5756 *
5757 * However, if we ignore data in ACKless segments sometimes,
5758 * we have no reasons to accept it sometimes.
5759 * Also, seems the code doing it in step6 of tcp_rcv_state_process
5760 * is not flawless. So, discard packet for sanity.
5761 * Uncomment this return to process the data.
5762 */
5763 return -1;
5764#else
5765 goto discard;
5766#endif
5767 }
5768 /* "fifth, if neither of the SYN or RST bits is set then
5769 * drop the segment and return."
5770 */
5771
5772discard_and_undo:
5773 tcp_clear_options(&tp->rx_opt);
5774 tp->rx_opt.mss_clamp = saved_clamp;
5775 goto discard;
5776
5777reset_and_undo:
5778 tcp_clear_options(&tp->rx_opt);
5779 tp->rx_opt.mss_clamp = saved_clamp;
5780 return 1;
5781}
5782
Linus Torvalds1da177e2005-04-16 15:20:36 -07005783/*
5784 * This function implements the receiving procedure of RFC 793 for
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005785 * all states except ESTABLISHED and TIME_WAIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -07005786 * It's called from both tcp_v4_rcv and tcp_v6_rcv and should be
5787 * address independent.
5788 */
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005789
Linus Torvalds1da177e2005-04-16 15:20:36 -07005790int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
Eric Dumazetcf533ea2011-10-21 05:22:42 -04005791 const struct tcphdr *th, unsigned int len)
Linus Torvalds1da177e2005-04-16 15:20:36 -07005792{
5793 struct tcp_sock *tp = tcp_sk(sk);
Arnaldo Carvalho de Melo8292a172005-12-13 23:15:52 -08005794 struct inet_connection_sock *icsk = inet_csk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005795 int queued = 0;
Ilpo Järvinencbe2d122008-08-23 05:10:12 -07005796 int res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07005797
5798 tp->rx_opt.saw_tstamp = 0;
5799
5800 switch (sk->sk_state) {
5801 case TCP_CLOSE:
5802 goto discard;
5803
5804 case TCP_LISTEN:
Stephen Hemminger2de979b2007-03-08 20:45:19 -08005805 if (th->ack)
Linus Torvalds1da177e2005-04-16 15:20:36 -07005806 return 1;
5807
Stephen Hemminger2de979b2007-03-08 20:45:19 -08005808 if (th->rst)
Linus Torvalds1da177e2005-04-16 15:20:36 -07005809 goto discard;
5810
Stephen Hemminger2de979b2007-03-08 20:45:19 -08005811 if (th->syn) {
Arnaldo Carvalho de Melo8292a172005-12-13 23:15:52 -08005812 if (icsk->icsk_af_ops->conn_request(sk, skb) < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07005813 return 1;
5814
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005815 /* Now we have several options: In theory there is
5816 * nothing else in the frame. KA9Q has an option to
Linus Torvalds1da177e2005-04-16 15:20:36 -07005817 * send data with the syn, BSD accepts data with the
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005818 * syn up to the [to be] advertised window and
5819 * Solaris 2.1 gives you a protocol error. For now
5820 * we just ignore it, that fits the spec precisely
Linus Torvalds1da177e2005-04-16 15:20:36 -07005821 * and avoids incompatibilities. It would be nice in
5822 * future to drop through and process the data.
5823 *
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005824 * Now that TTCP is starting to be used we ought to
Linus Torvalds1da177e2005-04-16 15:20:36 -07005825 * queue this data.
5826 * But, this leaves one open to an easy denial of
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005827 * service attack, and SYN cookies can't defend
Linus Torvalds1da177e2005-04-16 15:20:36 -07005828 * against this problem. So, we drop the data
Masayuki Nakagawafb7e2392007-01-23 20:15:06 -08005829 * in the interest of security over speed unless
5830 * it's still in use.
Linus Torvalds1da177e2005-04-16 15:20:36 -07005831 */
Masayuki Nakagawafb7e2392007-01-23 20:15:06 -08005832 kfree_skb(skb);
5833 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07005834 }
5835 goto discard;
5836
5837 case TCP_SYN_SENT:
Linus Torvalds1da177e2005-04-16 15:20:36 -07005838 queued = tcp_rcv_synsent_state_process(sk, skb, th, len);
5839 if (queued >= 0)
5840 return queued;
5841
5842 /* Do step6 onward by hand. */
5843 tcp_urg(sk, skb, th);
5844 __kfree_skb(skb);
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07005845 tcp_data_snd_check(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005846 return 0;
5847 }
5848
Ilpo Järvinencbe2d122008-08-23 05:10:12 -07005849 res = tcp_validate_incoming(sk, skb, th, 0);
5850 if (res <= 0)
5851 return -res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07005852
5853 /* step 5: check the ACK field */
5854 if (th->ack) {
John Dykstra96e0bf42009-03-22 21:49:57 -07005855 int acceptable = tcp_ack(sk, skb, FLAG_SLOWPATH) > 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07005856
Stephen Hemminger2de979b2007-03-08 20:45:19 -08005857 switch (sk->sk_state) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07005858 case TCP_SYN_RECV:
5859 if (acceptable) {
5860 tp->copied_seq = tp->rcv_nxt;
Ralf Baechlee16aa202006-12-07 00:11:33 -08005861 smp_mb();
Linus Torvalds1da177e2005-04-16 15:20:36 -07005862 tcp_set_state(sk, TCP_ESTABLISHED);
5863 sk->sk_state_change(sk);
5864
5865 /* Note, that this wakeup is only for marginal
5866 * crossed SYN case. Passively open sockets
5867 * are not waked up, because sk->sk_sleep ==
5868 * NULL and sk->sk_socket == NULL.
5869 */
Pavel Emelyanov8d8ad9d2007-11-26 20:10:50 +08005870 if (sk->sk_socket)
5871 sk_wake_async(sk,
Ilpo Järvinen056834d2007-12-31 14:57:14 -08005872 SOCK_WAKE_IO, POLL_OUT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005873
5874 tp->snd_una = TCP_SKB_CB(skb)->ack_seq;
5875 tp->snd_wnd = ntohs(th->window) <<
5876 tp->rx_opt.snd_wscale;
Hantzis Fotisee7537b2009-03-02 22:42:02 -08005877 tcp_init_wl(tp, TCP_SKB_CB(skb)->seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005878
Linus Torvalds1da177e2005-04-16 15:20:36 -07005879 if (tp->rx_opt.tstamp_ok)
5880 tp->advmss -= TCPOLEN_TSTAMP_ALIGNED;
5881
5882 /* Make sure socket is routed, for
5883 * correct metrics.
5884 */
Arnaldo Carvalho de Melo8292a172005-12-13 23:15:52 -08005885 icsk->icsk_af_ops->rebuild_header(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005886
5887 tcp_init_metrics(sk);
5888
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -03005889 tcp_init_congestion_control(sk);
Stephen Hemminger317a76f2005-06-23 12:19:55 -07005890
Linus Torvalds1da177e2005-04-16 15:20:36 -07005891 /* Prevent spurious tcp_cwnd_restart() on
5892 * first data packet.
5893 */
5894 tp->lsndtime = tcp_time_stamp;
5895
John Heffner5d424d52006-03-20 17:53:41 -08005896 tcp_mtup_init(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005897 tcp_initialize_rcv_mss(sk);
5898 tcp_init_buffer_space(sk);
5899 tcp_fast_path_on(tp);
5900 } else {
5901 return 1;
5902 }
5903 break;
5904
5905 case TCP_FIN_WAIT1:
5906 if (tp->snd_una == tp->write_seq) {
5907 tcp_set_state(sk, TCP_FIN_WAIT2);
5908 sk->sk_shutdown |= SEND_SHUTDOWN;
Eric Dumazetb6c67122010-04-08 23:03:29 +00005909 dst_confirm(__sk_dst_get(sk));
Linus Torvalds1da177e2005-04-16 15:20:36 -07005910
5911 if (!sock_flag(sk, SOCK_DEAD))
5912 /* Wake up lingering close() */
5913 sk->sk_state_change(sk);
5914 else {
5915 int tmo;
5916
5917 if (tp->linger2 < 0 ||
5918 (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
5919 after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt))) {
5920 tcp_done(sk);
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07005921 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005922 return 1;
5923 }
5924
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07005925 tmo = tcp_fin_time(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005926 if (tmo > TCP_TIMEWAIT_LEN) {
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07005927 inet_csk_reset_keepalive_timer(sk, tmo - TCP_TIMEWAIT_LEN);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005928 } else if (th->fin || sock_owned_by_user(sk)) {
5929 /* Bad case. We could lose such FIN otherwise.
5930 * It is not a big problem, but it looks confusing
5931 * and not so rare event. We still can lose it now,
5932 * if it spins in bh_lock_sock(), but it is really
5933 * marginal case.
5934 */
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -07005935 inet_csk_reset_keepalive_timer(sk, tmo);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005936 } else {
5937 tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
5938 goto discard;
5939 }
5940 }
5941 }
5942 break;
5943
5944 case TCP_CLOSING:
5945 if (tp->snd_una == tp->write_seq) {
5946 tcp_time_wait(sk, TCP_TIME_WAIT, 0);
5947 goto discard;
5948 }
5949 break;
5950
5951 case TCP_LAST_ACK:
5952 if (tp->snd_una == tp->write_seq) {
5953 tcp_update_metrics(sk);
5954 tcp_done(sk);
5955 goto discard;
5956 }
5957 break;
5958 }
5959 } else
5960 goto discard;
5961
5962 /* step 6: check the URG bit */
5963 tcp_urg(sk, skb, th);
5964
5965 /* step 7: process the segment text */
5966 switch (sk->sk_state) {
5967 case TCP_CLOSE_WAIT:
5968 case TCP_CLOSING:
5969 case TCP_LAST_ACK:
5970 if (!before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt))
5971 break;
5972 case TCP_FIN_WAIT1:
5973 case TCP_FIN_WAIT2:
5974 /* RFC 793 says to queue data in these states,
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005975 * RFC 1122 says we MUST send a reset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07005976 * BSD 4.4 also does reset.
5977 */
5978 if (sk->sk_shutdown & RCV_SHUTDOWN) {
5979 if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
5980 after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt)) {
Pavel Emelyanovde0744a2008-07-16 20:31:16 -07005981 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005982 tcp_reset(sk);
5983 return 1;
5984 }
5985 }
5986 /* Fall through */
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005987 case TCP_ESTABLISHED:
Linus Torvalds1da177e2005-04-16 15:20:36 -07005988 tcp_data_queue(sk, skb);
5989 queued = 1;
5990 break;
5991 }
5992
5993 /* tcp_data could move socket to TIME-WAIT */
5994 if (sk->sk_state != TCP_CLOSE) {
Ilpo Järvinen9e412ba2007-04-20 22:18:02 -07005995 tcp_data_snd_check(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07005996 tcp_ack_snd_check(sk);
5997 }
5998
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005999 if (!queued) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07006000discard:
6001 __kfree_skb(skb);
6002 }
6003 return 0;
6004}
Linus Torvalds1da177e2005-04-16 15:20:36 -07006005EXPORT_SYMBOL(tcp_rcv_state_process);