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Arnaldo Carvalho de Meloe48c4142005-08-09 20:09:46 -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 * Generic TIME_WAIT sockets functions
7 *
8 * From code orinally in TCP
9 */
10
Ilpo Järvinen172589c2007-08-28 15:50:33 -070011#include <linux/kernel.h>
Arnaldo Carvalho de Meloe48c4142005-08-09 20:09:46 -070012#include <net/inet_hashtables.h>
13#include <net/inet_timewait_sock.h>
Arnaldo Carvalho de Melo696ab2d2005-08-09 20:45:03 -070014#include <net/ip.h>
Arnaldo Carvalho de Meloe48c4142005-08-09 20:09:46 -070015
16/* Must be called with locally disabled BHs. */
Adrian Bunkacd159b2007-07-14 19:00:59 -070017static void __inet_twsk_kill(struct inet_timewait_sock *tw,
18 struct inet_hashinfo *hashinfo)
Arnaldo Carvalho de Meloe48c4142005-08-09 20:09:46 -070019{
20 struct inet_bind_hashbucket *bhead;
21 struct inet_bind_bucket *tb;
22 /* Unlink from established hashes. */
Eric Dumazet81c3d542005-10-03 14:13:38 -070023 struct inet_ehash_bucket *ehead = inet_ehash_bucket(hashinfo, tw->tw_hash);
Arnaldo Carvalho de Meloe48c4142005-08-09 20:09:46 -070024
25 write_lock(&ehead->lock);
26 if (hlist_unhashed(&tw->tw_node)) {
27 write_unlock(&ehead->lock);
28 return;
29 }
30 __hlist_del(&tw->tw_node);
31 sk_node_init(&tw->tw_node);
32 write_unlock(&ehead->lock);
33
34 /* Disassociate with bind bucket. */
35 bhead = &hashinfo->bhash[inet_bhashfn(tw->tw_num, hashinfo->bhash_size)];
36 spin_lock(&bhead->lock);
37 tb = tw->tw_tb;
38 __hlist_del(&tw->tw_bind_node);
39 tw->tw_tb = NULL;
40 inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
41 spin_unlock(&bhead->lock);
42#ifdef SOCK_REFCNT_DEBUG
43 if (atomic_read(&tw->tw_refcnt) != 1) {
44 printk(KERN_DEBUG "%s timewait_sock %p refcnt=%d\n",
45 tw->tw_prot->name, tw, atomic_read(&tw->tw_refcnt));
46 }
47#endif
48 inet_twsk_put(tw);
49}
50
51/*
52 * Enter the time wait state. This is called with locally disabled BH.
53 * Essentially we whip up a timewait bucket, copy the relevant info into it
54 * from the SK, and mess with hash chains and list linkage.
55 */
56void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
57 struct inet_hashinfo *hashinfo)
58{
59 const struct inet_sock *inet = inet_sk(sk);
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -070060 const struct inet_connection_sock *icsk = inet_csk(sk);
Eric Dumazet81c3d542005-10-03 14:13:38 -070061 struct inet_ehash_bucket *ehead = inet_ehash_bucket(hashinfo, sk->sk_hash);
Arnaldo Carvalho de Meloe48c4142005-08-09 20:09:46 -070062 struct inet_bind_hashbucket *bhead;
63 /* Step 1: Put TW into bind hash. Original socket stays there too.
64 Note, that any socket with inet->num != 0 MUST be bound in
65 binding cache, even if it is closed.
66 */
67 bhead = &hashinfo->bhash[inet_bhashfn(inet->num, hashinfo->bhash_size)];
68 spin_lock(&bhead->lock);
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -070069 tw->tw_tb = icsk->icsk_bind_hash;
70 BUG_TRAP(icsk->icsk_bind_hash);
Arnaldo Carvalho de Meloe48c4142005-08-09 20:09:46 -070071 inet_twsk_add_bind_node(tw, &tw->tw_tb->owners);
72 spin_unlock(&bhead->lock);
73
74 write_lock(&ehead->lock);
75
76 /* Step 2: Remove SK from established hash. */
77 if (__sk_del_node_init(sk))
78 sock_prot_dec_use(sk->sk_prot);
79
Eric Dumazetdbca9b2752007-02-08 14:16:46 -080080 /* Step 3: Hash TW into TIMEWAIT chain. */
81 inet_twsk_add_node(tw, &ehead->twchain);
Arnaldo Carvalho de Meloe48c4142005-08-09 20:09:46 -070082 atomic_inc(&tw->tw_refcnt);
83
84 write_unlock(&ehead->lock);
85}
Arnaldo Carvalho de Meloc6762702005-08-09 20:09:59 -070086
Arnaldo Carvalho de Melo696ab2d2005-08-09 20:45:03 -070087EXPORT_SYMBOL_GPL(__inet_twsk_hashdance);
88
Arnaldo Carvalho de Meloc6762702005-08-09 20:09:59 -070089struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, const int state)
90{
Arnaldo Carvalho de Melo6d6ee432005-12-13 23:25:19 -080091 struct inet_timewait_sock *tw =
92 kmem_cache_alloc(sk->sk_prot_creator->twsk_prot->twsk_slab,
Christoph Lameter54e6ecb2006-12-06 20:33:16 -080093 GFP_ATOMIC);
Arnaldo Carvalho de Meloc6762702005-08-09 20:09:59 -070094 if (tw != NULL) {
95 const struct inet_sock *inet = inet_sk(sk);
96
97 /* Give us an identity. */
98 tw->tw_daddr = inet->daddr;
99 tw->tw_rcv_saddr = inet->rcv_saddr;
100 tw->tw_bound_dev_if = sk->sk_bound_dev_if;
101 tw->tw_num = inet->num;
102 tw->tw_state = TCP_TIME_WAIT;
103 tw->tw_substate = state;
104 tw->tw_sport = inet->sport;
105 tw->tw_dport = inet->dport;
106 tw->tw_family = sk->sk_family;
107 tw->tw_reuse = sk->sk_reuse;
Eric Dumazet81c3d542005-10-03 14:13:38 -0700108 tw->tw_hash = sk->sk_hash;
Arnaldo Carvalho de Meloc6762702005-08-09 20:09:59 -0700109 tw->tw_ipv6only = 0;
110 tw->tw_prot = sk->sk_prot_creator;
111 atomic_set(&tw->tw_refcnt, 1);
112 inet_twsk_dead_node_init(tw);
Arnaldo Carvalho de Meloeeb2b852005-10-10 21:25:23 -0700113 __module_get(tw->tw_prot->owner);
Arnaldo Carvalho de Meloc6762702005-08-09 20:09:59 -0700114 }
115
116 return tw;
117}
Arnaldo Carvalho de Melo696ab2d2005-08-09 20:45:03 -0700118
119EXPORT_SYMBOL_GPL(inet_twsk_alloc);
120
121/* Returns non-zero if quota exceeded. */
122static int inet_twdr_do_twkill_work(struct inet_timewait_death_row *twdr,
123 const int slot)
124{
125 struct inet_timewait_sock *tw;
126 struct hlist_node *node;
127 unsigned int killed;
128 int ret;
129
130 /* NOTE: compare this to previous version where lock
131 * was released after detaching chain. It was racy,
132 * because tw buckets are scheduled in not serialized context
133 * in 2.3 (with netfilter), and with softnet it is common, because
134 * soft irqs are not sequenced.
135 */
136 killed = 0;
137 ret = 0;
138rescan:
139 inet_twsk_for_each_inmate(tw, node, &twdr->cells[slot]) {
140 __inet_twsk_del_dead_node(tw);
141 spin_unlock(&twdr->death_lock);
142 __inet_twsk_kill(tw, twdr->hashinfo);
143 inet_twsk_put(tw);
144 killed++;
145 spin_lock(&twdr->death_lock);
146 if (killed > INET_TWDR_TWKILL_QUOTA) {
147 ret = 1;
148 break;
149 }
150
151 /* While we dropped twdr->death_lock, another cpu may have
152 * killed off the next TW bucket in the list, therefore
153 * do a fresh re-read of the hlist head node with the
154 * lock reacquired. We still use the hlist traversal
155 * macro in order to get the prefetches.
156 */
157 goto rescan;
158 }
159
160 twdr->tw_count -= killed;
161 NET_ADD_STATS_BH(LINUX_MIB_TIMEWAITED, killed);
162
163 return ret;
164}
165
166void inet_twdr_hangman(unsigned long data)
167{
168 struct inet_timewait_death_row *twdr;
169 int unsigned need_timer;
170
171 twdr = (struct inet_timewait_death_row *)data;
172 spin_lock(&twdr->death_lock);
173
174 if (twdr->tw_count == 0)
175 goto out;
176
177 need_timer = 0;
178 if (inet_twdr_do_twkill_work(twdr, twdr->slot)) {
179 twdr->thread_slots |= (1 << twdr->slot);
Arnaldo Carvalho de Melo696ab2d2005-08-09 20:45:03 -0700180 schedule_work(&twdr->twkill_work);
181 need_timer = 1;
182 } else {
183 /* We purged the entire slot, anything left? */
184 if (twdr->tw_count)
185 need_timer = 1;
186 }
187 twdr->slot = ((twdr->slot + 1) & (INET_TWDR_TWKILL_SLOTS - 1));
188 if (need_timer)
189 mod_timer(&twdr->tw_timer, jiffies + twdr->period);
190out:
191 spin_unlock(&twdr->death_lock);
192}
193
194EXPORT_SYMBOL_GPL(inet_twdr_hangman);
195
196extern void twkill_slots_invalid(void);
197
David Howells65f27f32006-11-22 14:55:48 +0000198void inet_twdr_twkill_work(struct work_struct *work)
Arnaldo Carvalho de Melo696ab2d2005-08-09 20:45:03 -0700199{
David Howells65f27f32006-11-22 14:55:48 +0000200 struct inet_timewait_death_row *twdr =
201 container_of(work, struct inet_timewait_death_row, twkill_work);
Arnaldo Carvalho de Melo696ab2d2005-08-09 20:45:03 -0700202 int i;
203
204 if ((INET_TWDR_TWKILL_SLOTS - 1) > (sizeof(twdr->thread_slots) * 8))
205 twkill_slots_invalid();
206
207 while (twdr->thread_slots) {
208 spin_lock_bh(&twdr->death_lock);
209 for (i = 0; i < INET_TWDR_TWKILL_SLOTS; i++) {
210 if (!(twdr->thread_slots & (1 << i)))
211 continue;
212
213 while (inet_twdr_do_twkill_work(twdr, i) != 0) {
214 if (need_resched()) {
215 spin_unlock_bh(&twdr->death_lock);
216 schedule();
217 spin_lock_bh(&twdr->death_lock);
218 }
219 }
220
221 twdr->thread_slots &= ~(1 << i);
222 }
223 spin_unlock_bh(&twdr->death_lock);
224 }
225}
226
227EXPORT_SYMBOL_GPL(inet_twdr_twkill_work);
228
229/* These are always called from BH context. See callers in
230 * tcp_input.c to verify this.
231 */
232
233/* This is for handling early-kills of TIME_WAIT sockets. */
234void inet_twsk_deschedule(struct inet_timewait_sock *tw,
235 struct inet_timewait_death_row *twdr)
236{
237 spin_lock(&twdr->death_lock);
238 if (inet_twsk_del_dead_node(tw)) {
239 inet_twsk_put(tw);
240 if (--twdr->tw_count == 0)
241 del_timer(&twdr->tw_timer);
242 }
243 spin_unlock(&twdr->death_lock);
244 __inet_twsk_kill(tw, twdr->hashinfo);
245}
246
247EXPORT_SYMBOL(inet_twsk_deschedule);
248
249void inet_twsk_schedule(struct inet_timewait_sock *tw,
250 struct inet_timewait_death_row *twdr,
251 const int timeo, const int timewait_len)
252{
253 struct hlist_head *list;
254 int slot;
255
256 /* timeout := RTO * 3.5
257 *
258 * 3.5 = 1+2+0.5 to wait for two retransmits.
259 *
260 * RATIONALE: if FIN arrived and we entered TIME-WAIT state,
261 * our ACK acking that FIN can be lost. If N subsequent retransmitted
262 * FINs (or previous seqments) are lost (probability of such event
263 * is p^(N+1), where p is probability to lose single packet and
264 * time to detect the loss is about RTO*(2^N - 1) with exponential
265 * backoff). Normal timewait length is calculated so, that we
266 * waited at least for one retransmitted FIN (maximal RTO is 120sec).
267 * [ BTW Linux. following BSD, violates this requirement waiting
268 * only for 60sec, we should wait at least for 240 secs.
269 * Well, 240 consumes too much of resources 8)
270 * ]
271 * This interval is not reduced to catch old duplicate and
272 * responces to our wandering segments living for two MSLs.
273 * However, if we use PAWS to detect
274 * old duplicates, we can reduce the interval to bounds required
275 * by RTO, rather than MSL. So, if peer understands PAWS, we
276 * kill tw bucket after 3.5*RTO (it is important that this number
277 * is greater than TS tick!) and detect old duplicates with help
278 * of PAWS.
279 */
280 slot = (timeo + (1 << INET_TWDR_RECYCLE_TICK) - 1) >> INET_TWDR_RECYCLE_TICK;
281
282 spin_lock(&twdr->death_lock);
283
284 /* Unlink it, if it was scheduled */
285 if (inet_twsk_del_dead_node(tw))
286 twdr->tw_count--;
287 else
288 atomic_inc(&tw->tw_refcnt);
289
290 if (slot >= INET_TWDR_RECYCLE_SLOTS) {
291 /* Schedule to slow timer */
292 if (timeo >= timewait_len) {
293 slot = INET_TWDR_TWKILL_SLOTS - 1;
294 } else {
Ilpo Järvinen172589c2007-08-28 15:50:33 -0700295 slot = DIV_ROUND_UP(timeo, twdr->period);
Arnaldo Carvalho de Melo696ab2d2005-08-09 20:45:03 -0700296 if (slot >= INET_TWDR_TWKILL_SLOTS)
297 slot = INET_TWDR_TWKILL_SLOTS - 1;
298 }
299 tw->tw_ttd = jiffies + timeo;
300 slot = (twdr->slot + slot) & (INET_TWDR_TWKILL_SLOTS - 1);
301 list = &twdr->cells[slot];
302 } else {
303 tw->tw_ttd = jiffies + (slot << INET_TWDR_RECYCLE_TICK);
304
305 if (twdr->twcal_hand < 0) {
306 twdr->twcal_hand = 0;
307 twdr->twcal_jiffie = jiffies;
308 twdr->twcal_timer.expires = twdr->twcal_jiffie +
309 (slot << INET_TWDR_RECYCLE_TICK);
310 add_timer(&twdr->twcal_timer);
311 } else {
312 if (time_after(twdr->twcal_timer.expires,
313 jiffies + (slot << INET_TWDR_RECYCLE_TICK)))
314 mod_timer(&twdr->twcal_timer,
315 jiffies + (slot << INET_TWDR_RECYCLE_TICK));
316 slot = (twdr->twcal_hand + slot) & (INET_TWDR_RECYCLE_SLOTS - 1);
317 }
318 list = &twdr->twcal_row[slot];
319 }
320
321 hlist_add_head(&tw->tw_death_node, list);
322
323 if (twdr->tw_count++ == 0)
324 mod_timer(&twdr->tw_timer, jiffies + twdr->period);
325 spin_unlock(&twdr->death_lock);
326}
327
328EXPORT_SYMBOL_GPL(inet_twsk_schedule);
329
330void inet_twdr_twcal_tick(unsigned long data)
331{
332 struct inet_timewait_death_row *twdr;
333 int n, slot;
334 unsigned long j;
335 unsigned long now = jiffies;
336 int killed = 0;
337 int adv = 0;
338
339 twdr = (struct inet_timewait_death_row *)data;
340
341 spin_lock(&twdr->death_lock);
342 if (twdr->twcal_hand < 0)
343 goto out;
344
345 slot = twdr->twcal_hand;
346 j = twdr->twcal_jiffie;
347
348 for (n = 0; n < INET_TWDR_RECYCLE_SLOTS; n++) {
349 if (time_before_eq(j, now)) {
350 struct hlist_node *node, *safe;
351 struct inet_timewait_sock *tw;
352
353 inet_twsk_for_each_inmate_safe(tw, node, safe,
354 &twdr->twcal_row[slot]) {
355 __inet_twsk_del_dead_node(tw);
356 __inet_twsk_kill(tw, twdr->hashinfo);
357 inet_twsk_put(tw);
358 killed++;
359 }
360 } else {
361 if (!adv) {
362 adv = 1;
363 twdr->twcal_jiffie = j;
364 twdr->twcal_hand = slot;
365 }
366
367 if (!hlist_empty(&twdr->twcal_row[slot])) {
368 mod_timer(&twdr->twcal_timer, j);
369 goto out;
370 }
371 }
372 j += 1 << INET_TWDR_RECYCLE_TICK;
373 slot = (slot + 1) & (INET_TWDR_RECYCLE_SLOTS - 1);
374 }
375 twdr->twcal_hand = -1;
376
377out:
378 if ((twdr->tw_count -= killed) == 0)
379 del_timer(&twdr->tw_timer);
380 NET_ADD_STATS_BH(LINUX_MIB_TIMEWAITKILLED, killed);
381 spin_unlock(&twdr->death_lock);
382}
383
384EXPORT_SYMBOL_GPL(inet_twdr_twcal_tick);