Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 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 | * |
| 8 | * Version: $Id: tcp_timer.c,v 1.88 2002/02/01 22:01:04 davem Exp $ |
| 9 | * |
Jesper Juhl | 02c30a8 | 2005-05-05 16:16:16 -0700 | [diff] [blame] | 10 | * Authors: Ross Biro |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
| 12 | * Mark Evans, <evansmp@uhura.aston.ac.uk> |
| 13 | * Corey Minyard <wf-rch!minyard@relay.EU.net> |
| 14 | * Florian La Roche, <flla@stud.uni-sb.de> |
| 15 | * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> |
| 16 | * Linus Torvalds, <torvalds@cs.helsinki.fi> |
| 17 | * Alan Cox, <gw4pts@gw4pts.ampr.org> |
| 18 | * Matthew Dillon, <dillon@apollo.west.oic.com> |
| 19 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> |
| 20 | * Jorge Cwik, <jorge@laser.satlink.net> |
| 21 | */ |
| 22 | |
| 23 | #include <linux/module.h> |
| 24 | #include <net/tcp.h> |
| 25 | |
| 26 | int sysctl_tcp_syn_retries = TCP_SYN_RETRIES; |
| 27 | int sysctl_tcp_synack_retries = TCP_SYNACK_RETRIES; |
| 28 | int sysctl_tcp_keepalive_time = TCP_KEEPALIVE_TIME; |
| 29 | int sysctl_tcp_keepalive_probes = TCP_KEEPALIVE_PROBES; |
| 30 | int sysctl_tcp_keepalive_intvl = TCP_KEEPALIVE_INTVL; |
| 31 | int sysctl_tcp_retries1 = TCP_RETR1; |
| 32 | int sysctl_tcp_retries2 = TCP_RETR2; |
| 33 | int sysctl_tcp_orphan_retries; |
| 34 | |
| 35 | static void tcp_write_timer(unsigned long); |
| 36 | static void tcp_delack_timer(unsigned long); |
| 37 | static void tcp_keepalive_timer (unsigned long data); |
| 38 | |
| 39 | #ifdef TCP_DEBUG |
| 40 | const char tcp_timer_bug_msg[] = KERN_DEBUG "tcpbug: unknown timer value\n"; |
| 41 | EXPORT_SYMBOL(tcp_timer_bug_msg); |
| 42 | #endif |
| 43 | |
| 44 | /* |
| 45 | * Using different timers for retransmit, delayed acks and probes |
| 46 | * We may wish use just one timer maintaining a list of expire jiffies |
| 47 | * to optimize. |
| 48 | */ |
| 49 | |
| 50 | void tcp_init_xmit_timers(struct sock *sk) |
| 51 | { |
| 52 | struct tcp_sock *tp = tcp_sk(sk); |
| 53 | |
| 54 | init_timer(&tp->retransmit_timer); |
| 55 | tp->retransmit_timer.function=&tcp_write_timer; |
| 56 | tp->retransmit_timer.data = (unsigned long) sk; |
| 57 | tp->pending = 0; |
| 58 | |
| 59 | init_timer(&tp->delack_timer); |
| 60 | tp->delack_timer.function=&tcp_delack_timer; |
| 61 | tp->delack_timer.data = (unsigned long) sk; |
| 62 | tp->ack.pending = 0; |
| 63 | |
| 64 | init_timer(&sk->sk_timer); |
| 65 | sk->sk_timer.function = &tcp_keepalive_timer; |
| 66 | sk->sk_timer.data = (unsigned long)sk; |
| 67 | } |
| 68 | |
| 69 | void tcp_clear_xmit_timers(struct sock *sk) |
| 70 | { |
| 71 | struct tcp_sock *tp = tcp_sk(sk); |
| 72 | |
| 73 | tp->pending = 0; |
| 74 | sk_stop_timer(sk, &tp->retransmit_timer); |
| 75 | |
| 76 | tp->ack.pending = 0; |
| 77 | tp->ack.blocked = 0; |
| 78 | sk_stop_timer(sk, &tp->delack_timer); |
| 79 | |
| 80 | sk_stop_timer(sk, &sk->sk_timer); |
| 81 | } |
| 82 | |
| 83 | static void tcp_write_err(struct sock *sk) |
| 84 | { |
| 85 | sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT; |
| 86 | sk->sk_error_report(sk); |
| 87 | |
| 88 | tcp_done(sk); |
| 89 | NET_INC_STATS_BH(LINUX_MIB_TCPABORTONTIMEOUT); |
| 90 | } |
| 91 | |
| 92 | /* Do not allow orphaned sockets to eat all our resources. |
| 93 | * This is direct violation of TCP specs, but it is required |
| 94 | * to prevent DoS attacks. It is called when a retransmission timeout |
| 95 | * or zero probe timeout occurs on orphaned socket. |
| 96 | * |
| 97 | * Criterium is still not confirmed experimentally and may change. |
| 98 | * We kill the socket, if: |
| 99 | * 1. If number of orphaned sockets exceeds an administratively configured |
| 100 | * limit. |
| 101 | * 2. If we have strong memory pressure. |
| 102 | */ |
| 103 | static int tcp_out_of_resources(struct sock *sk, int do_reset) |
| 104 | { |
| 105 | struct tcp_sock *tp = tcp_sk(sk); |
| 106 | int orphans = atomic_read(&tcp_orphan_count); |
| 107 | |
| 108 | /* If peer does not open window for long time, or did not transmit |
| 109 | * anything for long time, penalize it. */ |
| 110 | if ((s32)(tcp_time_stamp - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset) |
| 111 | orphans <<= 1; |
| 112 | |
| 113 | /* If some dubious ICMP arrived, penalize even more. */ |
| 114 | if (sk->sk_err_soft) |
| 115 | orphans <<= 1; |
| 116 | |
| 117 | if (orphans >= sysctl_tcp_max_orphans || |
| 118 | (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && |
| 119 | atomic_read(&tcp_memory_allocated) > sysctl_tcp_mem[2])) { |
| 120 | if (net_ratelimit()) |
| 121 | printk(KERN_INFO "Out of socket memory\n"); |
| 122 | |
| 123 | /* Catch exceptional cases, when connection requires reset. |
| 124 | * 1. Last segment was sent recently. */ |
| 125 | if ((s32)(tcp_time_stamp - tp->lsndtime) <= TCP_TIMEWAIT_LEN || |
| 126 | /* 2. Window is closed. */ |
| 127 | (!tp->snd_wnd && !tp->packets_out)) |
| 128 | do_reset = 1; |
| 129 | if (do_reset) |
| 130 | tcp_send_active_reset(sk, GFP_ATOMIC); |
| 131 | tcp_done(sk); |
| 132 | NET_INC_STATS_BH(LINUX_MIB_TCPABORTONMEMORY); |
| 133 | return 1; |
| 134 | } |
| 135 | return 0; |
| 136 | } |
| 137 | |
| 138 | /* Calculate maximal number or retries on an orphaned socket. */ |
| 139 | static int tcp_orphan_retries(struct sock *sk, int alive) |
| 140 | { |
| 141 | int retries = sysctl_tcp_orphan_retries; /* May be zero. */ |
| 142 | |
| 143 | /* We know from an ICMP that something is wrong. */ |
| 144 | if (sk->sk_err_soft && !alive) |
| 145 | retries = 0; |
| 146 | |
| 147 | /* However, if socket sent something recently, select some safe |
| 148 | * number of retries. 8 corresponds to >100 seconds with minimal |
| 149 | * RTO of 200msec. */ |
| 150 | if (retries == 0 && alive) |
| 151 | retries = 8; |
| 152 | return retries; |
| 153 | } |
| 154 | |
| 155 | /* A write timeout has occurred. Process the after effects. */ |
| 156 | static int tcp_write_timeout(struct sock *sk) |
| 157 | { |
| 158 | struct tcp_sock *tp = tcp_sk(sk); |
| 159 | int retry_until; |
| 160 | |
| 161 | if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { |
| 162 | if (tp->retransmits) |
| 163 | dst_negative_advice(&sk->sk_dst_cache); |
| 164 | retry_until = tp->syn_retries ? : sysctl_tcp_syn_retries; |
| 165 | } else { |
| 166 | if (tp->retransmits >= sysctl_tcp_retries1) { |
| 167 | /* NOTE. draft-ietf-tcpimpl-pmtud-01.txt requires pmtu black |
| 168 | hole detection. :-( |
| 169 | |
| 170 | It is place to make it. It is not made. I do not want |
| 171 | to make it. It is disguisting. It does not work in any |
| 172 | case. Let me to cite the same draft, which requires for |
| 173 | us to implement this: |
| 174 | |
| 175 | "The one security concern raised by this memo is that ICMP black holes |
| 176 | are often caused by over-zealous security administrators who block |
| 177 | all ICMP messages. It is vitally important that those who design and |
| 178 | deploy security systems understand the impact of strict filtering on |
| 179 | upper-layer protocols. The safest web site in the world is worthless |
| 180 | if most TCP implementations cannot transfer data from it. It would |
| 181 | be far nicer to have all of the black holes fixed rather than fixing |
| 182 | all of the TCP implementations." |
| 183 | |
| 184 | Golden words :-). |
| 185 | */ |
| 186 | |
| 187 | dst_negative_advice(&sk->sk_dst_cache); |
| 188 | } |
| 189 | |
| 190 | retry_until = sysctl_tcp_retries2; |
| 191 | if (sock_flag(sk, SOCK_DEAD)) { |
| 192 | int alive = (tp->rto < TCP_RTO_MAX); |
| 193 | |
| 194 | retry_until = tcp_orphan_retries(sk, alive); |
| 195 | |
| 196 | if (tcp_out_of_resources(sk, alive || tp->retransmits < retry_until)) |
| 197 | return 1; |
| 198 | } |
| 199 | } |
| 200 | |
| 201 | if (tp->retransmits >= retry_until) { |
| 202 | /* Has it gone just too far? */ |
| 203 | tcp_write_err(sk); |
| 204 | return 1; |
| 205 | } |
| 206 | return 0; |
| 207 | } |
| 208 | |
| 209 | static void tcp_delack_timer(unsigned long data) |
| 210 | { |
| 211 | struct sock *sk = (struct sock*)data; |
| 212 | struct tcp_sock *tp = tcp_sk(sk); |
| 213 | |
| 214 | bh_lock_sock(sk); |
| 215 | if (sock_owned_by_user(sk)) { |
| 216 | /* Try again later. */ |
| 217 | tp->ack.blocked = 1; |
| 218 | NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKLOCKED); |
| 219 | sk_reset_timer(sk, &tp->delack_timer, jiffies + TCP_DELACK_MIN); |
| 220 | goto out_unlock; |
| 221 | } |
| 222 | |
| 223 | sk_stream_mem_reclaim(sk); |
| 224 | |
| 225 | if (sk->sk_state == TCP_CLOSE || !(tp->ack.pending & TCP_ACK_TIMER)) |
| 226 | goto out; |
| 227 | |
| 228 | if (time_after(tp->ack.timeout, jiffies)) { |
| 229 | sk_reset_timer(sk, &tp->delack_timer, tp->ack.timeout); |
| 230 | goto out; |
| 231 | } |
| 232 | tp->ack.pending &= ~TCP_ACK_TIMER; |
| 233 | |
| 234 | if (skb_queue_len(&tp->ucopy.prequeue)) { |
| 235 | struct sk_buff *skb; |
| 236 | |
| 237 | NET_ADD_STATS_BH(LINUX_MIB_TCPSCHEDULERFAILED, |
| 238 | skb_queue_len(&tp->ucopy.prequeue)); |
| 239 | |
| 240 | while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) |
| 241 | sk->sk_backlog_rcv(sk, skb); |
| 242 | |
| 243 | tp->ucopy.memory = 0; |
| 244 | } |
| 245 | |
| 246 | if (tcp_ack_scheduled(tp)) { |
| 247 | if (!tp->ack.pingpong) { |
| 248 | /* Delayed ACK missed: inflate ATO. */ |
| 249 | tp->ack.ato = min(tp->ack.ato << 1, tp->rto); |
| 250 | } else { |
| 251 | /* Delayed ACK missed: leave pingpong mode and |
| 252 | * deflate ATO. |
| 253 | */ |
| 254 | tp->ack.pingpong = 0; |
| 255 | tp->ack.ato = TCP_ATO_MIN; |
| 256 | } |
| 257 | tcp_send_ack(sk); |
| 258 | NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKS); |
| 259 | } |
| 260 | TCP_CHECK_TIMER(sk); |
| 261 | |
| 262 | out: |
| 263 | if (tcp_memory_pressure) |
| 264 | sk_stream_mem_reclaim(sk); |
| 265 | out_unlock: |
| 266 | bh_unlock_sock(sk); |
| 267 | sock_put(sk); |
| 268 | } |
| 269 | |
| 270 | static void tcp_probe_timer(struct sock *sk) |
| 271 | { |
| 272 | struct tcp_sock *tp = tcp_sk(sk); |
| 273 | int max_probes; |
| 274 | |
| 275 | if (tp->packets_out || !sk->sk_send_head) { |
| 276 | tp->probes_out = 0; |
| 277 | return; |
| 278 | } |
| 279 | |
| 280 | /* *WARNING* RFC 1122 forbids this |
| 281 | * |
| 282 | * It doesn't AFAIK, because we kill the retransmit timer -AK |
| 283 | * |
| 284 | * FIXME: We ought not to do it, Solaris 2.5 actually has fixing |
| 285 | * this behaviour in Solaris down as a bug fix. [AC] |
| 286 | * |
| 287 | * Let me to explain. probes_out is zeroed by incoming ACKs |
| 288 | * even if they advertise zero window. Hence, connection is killed only |
| 289 | * if we received no ACKs for normal connection timeout. It is not killed |
| 290 | * only because window stays zero for some time, window may be zero |
| 291 | * until armageddon and even later. We are in full accordance |
| 292 | * with RFCs, only probe timer combines both retransmission timeout |
| 293 | * and probe timeout in one bottle. --ANK |
| 294 | */ |
| 295 | max_probes = sysctl_tcp_retries2; |
| 296 | |
| 297 | if (sock_flag(sk, SOCK_DEAD)) { |
| 298 | int alive = ((tp->rto<<tp->backoff) < TCP_RTO_MAX); |
| 299 | |
| 300 | max_probes = tcp_orphan_retries(sk, alive); |
| 301 | |
| 302 | if (tcp_out_of_resources(sk, alive || tp->probes_out <= max_probes)) |
| 303 | return; |
| 304 | } |
| 305 | |
| 306 | if (tp->probes_out > max_probes) { |
| 307 | tcp_write_err(sk); |
| 308 | } else { |
| 309 | /* Only send another probe if we didn't close things up. */ |
| 310 | tcp_send_probe0(sk); |
| 311 | } |
| 312 | } |
| 313 | |
| 314 | /* |
| 315 | * The TCP retransmit timer. |
| 316 | */ |
| 317 | |
| 318 | static void tcp_retransmit_timer(struct sock *sk) |
| 319 | { |
| 320 | struct tcp_sock *tp = tcp_sk(sk); |
| 321 | |
| 322 | if (!tp->packets_out) |
| 323 | goto out; |
| 324 | |
| 325 | BUG_TRAP(!skb_queue_empty(&sk->sk_write_queue)); |
| 326 | |
| 327 | if (!tp->snd_wnd && !sock_flag(sk, SOCK_DEAD) && |
| 328 | !((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))) { |
| 329 | /* Receiver dastardly shrinks window. Our retransmits |
| 330 | * become zero probes, but we should not timeout this |
| 331 | * connection. If the socket is an orphan, time it out, |
| 332 | * we cannot allow such beasts to hang infinitely. |
| 333 | */ |
| 334 | #ifdef TCP_DEBUG |
| 335 | if (net_ratelimit()) { |
| 336 | struct inet_sock *inet = inet_sk(sk); |
| 337 | printk(KERN_DEBUG "TCP: Treason uncloaked! Peer %u.%u.%u.%u:%u/%u shrinks window %u:%u. Repaired.\n", |
| 338 | NIPQUAD(inet->daddr), htons(inet->dport), |
| 339 | inet->num, tp->snd_una, tp->snd_nxt); |
| 340 | } |
| 341 | #endif |
| 342 | if (tcp_time_stamp - tp->rcv_tstamp > TCP_RTO_MAX) { |
| 343 | tcp_write_err(sk); |
| 344 | goto out; |
| 345 | } |
| 346 | tcp_enter_loss(sk, 0); |
| 347 | tcp_retransmit_skb(sk, skb_peek(&sk->sk_write_queue)); |
| 348 | __sk_dst_reset(sk); |
| 349 | goto out_reset_timer; |
| 350 | } |
| 351 | |
| 352 | if (tcp_write_timeout(sk)) |
| 353 | goto out; |
| 354 | |
| 355 | if (tp->retransmits == 0) { |
| 356 | if (tp->ca_state == TCP_CA_Disorder || tp->ca_state == TCP_CA_Recovery) { |
| 357 | if (tp->rx_opt.sack_ok) { |
| 358 | if (tp->ca_state == TCP_CA_Recovery) |
| 359 | NET_INC_STATS_BH(LINUX_MIB_TCPSACKRECOVERYFAIL); |
| 360 | else |
| 361 | NET_INC_STATS_BH(LINUX_MIB_TCPSACKFAILURES); |
| 362 | } else { |
| 363 | if (tp->ca_state == TCP_CA_Recovery) |
| 364 | NET_INC_STATS_BH(LINUX_MIB_TCPRENORECOVERYFAIL); |
| 365 | else |
| 366 | NET_INC_STATS_BH(LINUX_MIB_TCPRENOFAILURES); |
| 367 | } |
| 368 | } else if (tp->ca_state == TCP_CA_Loss) { |
| 369 | NET_INC_STATS_BH(LINUX_MIB_TCPLOSSFAILURES); |
| 370 | } else { |
| 371 | NET_INC_STATS_BH(LINUX_MIB_TCPTIMEOUTS); |
| 372 | } |
| 373 | } |
| 374 | |
| 375 | if (tcp_use_frto(sk)) { |
| 376 | tcp_enter_frto(sk); |
| 377 | } else { |
| 378 | tcp_enter_loss(sk, 0); |
| 379 | } |
| 380 | |
| 381 | if (tcp_retransmit_skb(sk, skb_peek(&sk->sk_write_queue)) > 0) { |
| 382 | /* Retransmission failed because of local congestion, |
| 383 | * do not backoff. |
| 384 | */ |
| 385 | if (!tp->retransmits) |
| 386 | tp->retransmits=1; |
| 387 | tcp_reset_xmit_timer(sk, TCP_TIME_RETRANS, |
| 388 | min(tp->rto, TCP_RESOURCE_PROBE_INTERVAL)); |
| 389 | goto out; |
| 390 | } |
| 391 | |
| 392 | /* Increase the timeout each time we retransmit. Note that |
| 393 | * we do not increase the rtt estimate. rto is initialized |
| 394 | * from rtt, but increases here. Jacobson (SIGCOMM 88) suggests |
| 395 | * that doubling rto each time is the least we can get away with. |
| 396 | * In KA9Q, Karn uses this for the first few times, and then |
| 397 | * goes to quadratic. netBSD doubles, but only goes up to *64, |
| 398 | * and clamps at 1 to 64 sec afterwards. Note that 120 sec is |
| 399 | * defined in the protocol as the maximum possible RTT. I guess |
| 400 | * we'll have to use something other than TCP to talk to the |
| 401 | * University of Mars. |
| 402 | * |
| 403 | * PAWS allows us longer timeouts and large windows, so once |
| 404 | * implemented ftp to mars will work nicely. We will have to fix |
| 405 | * the 120 second clamps though! |
| 406 | */ |
| 407 | tp->backoff++; |
| 408 | tp->retransmits++; |
| 409 | |
| 410 | out_reset_timer: |
| 411 | tp->rto = min(tp->rto << 1, TCP_RTO_MAX); |
| 412 | tcp_reset_xmit_timer(sk, TCP_TIME_RETRANS, tp->rto); |
| 413 | if (tp->retransmits > sysctl_tcp_retries1) |
| 414 | __sk_dst_reset(sk); |
| 415 | |
| 416 | out:; |
| 417 | } |
| 418 | |
| 419 | static void tcp_write_timer(unsigned long data) |
| 420 | { |
| 421 | struct sock *sk = (struct sock*)data; |
| 422 | struct tcp_sock *tp = tcp_sk(sk); |
| 423 | int event; |
| 424 | |
| 425 | bh_lock_sock(sk); |
| 426 | if (sock_owned_by_user(sk)) { |
| 427 | /* Try again later */ |
| 428 | sk_reset_timer(sk, &tp->retransmit_timer, jiffies + (HZ / 20)); |
| 429 | goto out_unlock; |
| 430 | } |
| 431 | |
| 432 | if (sk->sk_state == TCP_CLOSE || !tp->pending) |
| 433 | goto out; |
| 434 | |
| 435 | if (time_after(tp->timeout, jiffies)) { |
| 436 | sk_reset_timer(sk, &tp->retransmit_timer, tp->timeout); |
| 437 | goto out; |
| 438 | } |
| 439 | |
| 440 | event = tp->pending; |
| 441 | tp->pending = 0; |
| 442 | |
| 443 | switch (event) { |
| 444 | case TCP_TIME_RETRANS: |
| 445 | tcp_retransmit_timer(sk); |
| 446 | break; |
| 447 | case TCP_TIME_PROBE0: |
| 448 | tcp_probe_timer(sk); |
| 449 | break; |
| 450 | } |
| 451 | TCP_CHECK_TIMER(sk); |
| 452 | |
| 453 | out: |
| 454 | sk_stream_mem_reclaim(sk); |
| 455 | out_unlock: |
| 456 | bh_unlock_sock(sk); |
| 457 | sock_put(sk); |
| 458 | } |
| 459 | |
| 460 | /* |
| 461 | * Timer for listening sockets |
| 462 | */ |
| 463 | |
| 464 | static void tcp_synack_timer(struct sock *sk) |
| 465 | { |
| 466 | struct tcp_sock *tp = tcp_sk(sk); |
| 467 | struct tcp_listen_opt *lopt = tp->listen_opt; |
| 468 | int max_retries = tp->syn_retries ? : sysctl_tcp_synack_retries; |
| 469 | int thresh = max_retries; |
| 470 | unsigned long now = jiffies; |
| 471 | struct open_request **reqp, *req; |
| 472 | int i, budget; |
| 473 | |
| 474 | if (lopt == NULL || lopt->qlen == 0) |
| 475 | return; |
| 476 | |
| 477 | /* Normally all the openreqs are young and become mature |
| 478 | * (i.e. converted to established socket) for first timeout. |
| 479 | * If synack was not acknowledged for 3 seconds, it means |
| 480 | * one of the following things: synack was lost, ack was lost, |
| 481 | * rtt is high or nobody planned to ack (i.e. synflood). |
| 482 | * When server is a bit loaded, queue is populated with old |
| 483 | * open requests, reducing effective size of queue. |
| 484 | * When server is well loaded, queue size reduces to zero |
| 485 | * after several minutes of work. It is not synflood, |
| 486 | * it is normal operation. The solution is pruning |
| 487 | * too old entries overriding normal timeout, when |
| 488 | * situation becomes dangerous. |
| 489 | * |
| 490 | * Essentially, we reserve half of room for young |
| 491 | * embrions; and abort old ones without pity, if old |
| 492 | * ones are about to clog our table. |
| 493 | */ |
| 494 | if (lopt->qlen>>(lopt->max_qlen_log-1)) { |
| 495 | int young = (lopt->qlen_young<<1); |
| 496 | |
| 497 | while (thresh > 2) { |
| 498 | if (lopt->qlen < young) |
| 499 | break; |
| 500 | thresh--; |
| 501 | young <<= 1; |
| 502 | } |
| 503 | } |
| 504 | |
| 505 | if (tp->defer_accept) |
| 506 | max_retries = tp->defer_accept; |
| 507 | |
| 508 | budget = 2*(TCP_SYNQ_HSIZE/(TCP_TIMEOUT_INIT/TCP_SYNQ_INTERVAL)); |
| 509 | i = lopt->clock_hand; |
| 510 | |
| 511 | do { |
| 512 | reqp=&lopt->syn_table[i]; |
| 513 | while ((req = *reqp) != NULL) { |
| 514 | if (time_after_eq(now, req->expires)) { |
| 515 | if ((req->retrans < thresh || |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame^] | 516 | (inet_rsk(req)->acked && req->retrans < max_retries)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 517 | && !req->class->rtx_syn_ack(sk, req, NULL)) { |
| 518 | unsigned long timeo; |
| 519 | |
| 520 | if (req->retrans++ == 0) |
| 521 | lopt->qlen_young--; |
| 522 | timeo = min((TCP_TIMEOUT_INIT << req->retrans), |
| 523 | TCP_RTO_MAX); |
| 524 | req->expires = now + timeo; |
| 525 | reqp = &req->dl_next; |
| 526 | continue; |
| 527 | } |
| 528 | |
| 529 | /* Drop this request */ |
| 530 | write_lock(&tp->syn_wait_lock); |
| 531 | *reqp = req->dl_next; |
| 532 | write_unlock(&tp->syn_wait_lock); |
| 533 | lopt->qlen--; |
| 534 | if (req->retrans == 0) |
| 535 | lopt->qlen_young--; |
| 536 | tcp_openreq_free(req); |
| 537 | continue; |
| 538 | } |
| 539 | reqp = &req->dl_next; |
| 540 | } |
| 541 | |
| 542 | i = (i+1)&(TCP_SYNQ_HSIZE-1); |
| 543 | |
| 544 | } while (--budget > 0); |
| 545 | |
| 546 | lopt->clock_hand = i; |
| 547 | |
| 548 | if (lopt->qlen) |
| 549 | tcp_reset_keepalive_timer(sk, TCP_SYNQ_INTERVAL); |
| 550 | } |
| 551 | |
| 552 | void tcp_delete_keepalive_timer (struct sock *sk) |
| 553 | { |
| 554 | sk_stop_timer(sk, &sk->sk_timer); |
| 555 | } |
| 556 | |
| 557 | void tcp_reset_keepalive_timer (struct sock *sk, unsigned long len) |
| 558 | { |
| 559 | sk_reset_timer(sk, &sk->sk_timer, jiffies + len); |
| 560 | } |
| 561 | |
| 562 | void tcp_set_keepalive(struct sock *sk, int val) |
| 563 | { |
| 564 | if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) |
| 565 | return; |
| 566 | |
| 567 | if (val && !sock_flag(sk, SOCK_KEEPOPEN)) |
| 568 | tcp_reset_keepalive_timer(sk, keepalive_time_when(tcp_sk(sk))); |
| 569 | else if (!val) |
| 570 | tcp_delete_keepalive_timer(sk); |
| 571 | } |
| 572 | |
| 573 | |
| 574 | static void tcp_keepalive_timer (unsigned long data) |
| 575 | { |
| 576 | struct sock *sk = (struct sock *) data; |
| 577 | struct tcp_sock *tp = tcp_sk(sk); |
| 578 | __u32 elapsed; |
| 579 | |
| 580 | /* Only process if socket is not in use. */ |
| 581 | bh_lock_sock(sk); |
| 582 | if (sock_owned_by_user(sk)) { |
| 583 | /* Try again later. */ |
| 584 | tcp_reset_keepalive_timer (sk, HZ/20); |
| 585 | goto out; |
| 586 | } |
| 587 | |
| 588 | if (sk->sk_state == TCP_LISTEN) { |
| 589 | tcp_synack_timer(sk); |
| 590 | goto out; |
| 591 | } |
| 592 | |
| 593 | if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) { |
| 594 | if (tp->linger2 >= 0) { |
| 595 | int tmo = tcp_fin_time(tp) - TCP_TIMEWAIT_LEN; |
| 596 | |
| 597 | if (tmo > 0) { |
| 598 | tcp_time_wait(sk, TCP_FIN_WAIT2, tmo); |
| 599 | goto out; |
| 600 | } |
| 601 | } |
| 602 | tcp_send_active_reset(sk, GFP_ATOMIC); |
| 603 | goto death; |
| 604 | } |
| 605 | |
| 606 | if (!sock_flag(sk, SOCK_KEEPOPEN) || sk->sk_state == TCP_CLOSE) |
| 607 | goto out; |
| 608 | |
| 609 | elapsed = keepalive_time_when(tp); |
| 610 | |
| 611 | /* It is alive without keepalive 8) */ |
| 612 | if (tp->packets_out || sk->sk_send_head) |
| 613 | goto resched; |
| 614 | |
| 615 | elapsed = tcp_time_stamp - tp->rcv_tstamp; |
| 616 | |
| 617 | if (elapsed >= keepalive_time_when(tp)) { |
| 618 | if ((!tp->keepalive_probes && tp->probes_out >= sysctl_tcp_keepalive_probes) || |
| 619 | (tp->keepalive_probes && tp->probes_out >= tp->keepalive_probes)) { |
| 620 | tcp_send_active_reset(sk, GFP_ATOMIC); |
| 621 | tcp_write_err(sk); |
| 622 | goto out; |
| 623 | } |
| 624 | if (tcp_write_wakeup(sk) <= 0) { |
| 625 | tp->probes_out++; |
| 626 | elapsed = keepalive_intvl_when(tp); |
| 627 | } else { |
| 628 | /* If keepalive was lost due to local congestion, |
| 629 | * try harder. |
| 630 | */ |
| 631 | elapsed = TCP_RESOURCE_PROBE_INTERVAL; |
| 632 | } |
| 633 | } else { |
| 634 | /* It is tp->rcv_tstamp + keepalive_time_when(tp) */ |
| 635 | elapsed = keepalive_time_when(tp) - elapsed; |
| 636 | } |
| 637 | |
| 638 | TCP_CHECK_TIMER(sk); |
| 639 | sk_stream_mem_reclaim(sk); |
| 640 | |
| 641 | resched: |
| 642 | tcp_reset_keepalive_timer (sk, elapsed); |
| 643 | goto out; |
| 644 | |
| 645 | death: |
| 646 | tcp_done(sk); |
| 647 | |
| 648 | out: |
| 649 | bh_unlock_sock(sk); |
| 650 | sock_put(sk); |
| 651 | } |
| 652 | |
| 653 | EXPORT_SYMBOL(tcp_clear_xmit_timers); |
| 654 | EXPORT_SYMBOL(tcp_delete_keepalive_timer); |
| 655 | EXPORT_SYMBOL(tcp_init_xmit_timers); |
| 656 | EXPORT_SYMBOL(tcp_reset_keepalive_timer); |