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1da177e4 LT |
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 | * | |
02c30a84 | 10 | * Authors: Ross Biro |
1da177e4 LT |
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 || | |
516 | (req->acked && req->retrans < max_retries)) | |
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); |