Commit | Line | Data |
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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 | ||
463c84b9 ACM |
39 | void tcp_init_xmit_timers(struct sock *sk) |
40 | { | |
41 | inet_csk_init_xmit_timers(sk, &tcp_write_timer, &tcp_delack_timer, | |
42 | &tcp_keepalive_timer); | |
43 | } | |
44 | ||
3f421baa ACM |
45 | EXPORT_SYMBOL(tcp_init_xmit_timers); |
46 | ||
1da177e4 LT |
47 | static void tcp_write_err(struct sock *sk) |
48 | { | |
49 | sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT; | |
50 | sk->sk_error_report(sk); | |
51 | ||
52 | tcp_done(sk); | |
53 | NET_INC_STATS_BH(LINUX_MIB_TCPABORTONTIMEOUT); | |
54 | } | |
55 | ||
56 | /* Do not allow orphaned sockets to eat all our resources. | |
57 | * This is direct violation of TCP specs, but it is required | |
58 | * to prevent DoS attacks. It is called when a retransmission timeout | |
59 | * or zero probe timeout occurs on orphaned socket. | |
60 | * | |
61 | * Criterium is still not confirmed experimentally and may change. | |
62 | * We kill the socket, if: | |
63 | * 1. If number of orphaned sockets exceeds an administratively configured | |
64 | * limit. | |
65 | * 2. If we have strong memory pressure. | |
66 | */ | |
67 | static int tcp_out_of_resources(struct sock *sk, int do_reset) | |
68 | { | |
69 | struct tcp_sock *tp = tcp_sk(sk); | |
70 | int orphans = atomic_read(&tcp_orphan_count); | |
71 | ||
72 | /* If peer does not open window for long time, or did not transmit | |
73 | * anything for long time, penalize it. */ | |
74 | if ((s32)(tcp_time_stamp - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset) | |
75 | orphans <<= 1; | |
76 | ||
77 | /* If some dubious ICMP arrived, penalize even more. */ | |
78 | if (sk->sk_err_soft) | |
79 | orphans <<= 1; | |
80 | ||
81 | if (orphans >= sysctl_tcp_max_orphans || | |
82 | (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && | |
83 | atomic_read(&tcp_memory_allocated) > sysctl_tcp_mem[2])) { | |
84 | if (net_ratelimit()) | |
85 | printk(KERN_INFO "Out of socket memory\n"); | |
86 | ||
87 | /* Catch exceptional cases, when connection requires reset. | |
88 | * 1. Last segment was sent recently. */ | |
89 | if ((s32)(tcp_time_stamp - tp->lsndtime) <= TCP_TIMEWAIT_LEN || | |
90 | /* 2. Window is closed. */ | |
91 | (!tp->snd_wnd && !tp->packets_out)) | |
92 | do_reset = 1; | |
93 | if (do_reset) | |
94 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
95 | tcp_done(sk); | |
96 | NET_INC_STATS_BH(LINUX_MIB_TCPABORTONMEMORY); | |
97 | return 1; | |
98 | } | |
99 | return 0; | |
100 | } | |
101 | ||
102 | /* Calculate maximal number or retries on an orphaned socket. */ | |
103 | static int tcp_orphan_retries(struct sock *sk, int alive) | |
104 | { | |
105 | int retries = sysctl_tcp_orphan_retries; /* May be zero. */ | |
106 | ||
107 | /* We know from an ICMP that something is wrong. */ | |
108 | if (sk->sk_err_soft && !alive) | |
109 | retries = 0; | |
110 | ||
111 | /* However, if socket sent something recently, select some safe | |
112 | * number of retries. 8 corresponds to >100 seconds with minimal | |
113 | * RTO of 200msec. */ | |
114 | if (retries == 0 && alive) | |
115 | retries = 8; | |
116 | return retries; | |
117 | } | |
118 | ||
119 | /* A write timeout has occurred. Process the after effects. */ | |
120 | static int tcp_write_timeout(struct sock *sk) | |
121 | { | |
463c84b9 | 122 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
123 | int retry_until; |
124 | ||
125 | if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { | |
463c84b9 | 126 | if (icsk->icsk_retransmits) |
1da177e4 | 127 | dst_negative_advice(&sk->sk_dst_cache); |
463c84b9 | 128 | retry_until = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries; |
1da177e4 | 129 | } else { |
463c84b9 | 130 | if (icsk->icsk_retransmits >= sysctl_tcp_retries1) { |
1da177e4 LT |
131 | /* NOTE. draft-ietf-tcpimpl-pmtud-01.txt requires pmtu black |
132 | hole detection. :-( | |
133 | ||
134 | It is place to make it. It is not made. I do not want | |
135 | to make it. It is disguisting. It does not work in any | |
136 | case. Let me to cite the same draft, which requires for | |
137 | us to implement this: | |
138 | ||
139 | "The one security concern raised by this memo is that ICMP black holes | |
140 | are often caused by over-zealous security administrators who block | |
141 | all ICMP messages. It is vitally important that those who design and | |
142 | deploy security systems understand the impact of strict filtering on | |
143 | upper-layer protocols. The safest web site in the world is worthless | |
144 | if most TCP implementations cannot transfer data from it. It would | |
145 | be far nicer to have all of the black holes fixed rather than fixing | |
146 | all of the TCP implementations." | |
147 | ||
148 | Golden words :-). | |
149 | */ | |
150 | ||
151 | dst_negative_advice(&sk->sk_dst_cache); | |
152 | } | |
153 | ||
154 | retry_until = sysctl_tcp_retries2; | |
155 | if (sock_flag(sk, SOCK_DEAD)) { | |
463c84b9 | 156 | const int alive = (icsk->icsk_rto < TCP_RTO_MAX); |
1da177e4 LT |
157 | |
158 | retry_until = tcp_orphan_retries(sk, alive); | |
159 | ||
463c84b9 | 160 | if (tcp_out_of_resources(sk, alive || icsk->icsk_retransmits < retry_until)) |
1da177e4 LT |
161 | return 1; |
162 | } | |
163 | } | |
164 | ||
463c84b9 | 165 | if (icsk->icsk_retransmits >= retry_until) { |
1da177e4 LT |
166 | /* Has it gone just too far? */ |
167 | tcp_write_err(sk); | |
168 | return 1; | |
169 | } | |
170 | return 0; | |
171 | } | |
172 | ||
173 | static void tcp_delack_timer(unsigned long data) | |
174 | { | |
175 | struct sock *sk = (struct sock*)data; | |
176 | struct tcp_sock *tp = tcp_sk(sk); | |
463c84b9 | 177 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
178 | |
179 | bh_lock_sock(sk); | |
180 | if (sock_owned_by_user(sk)) { | |
181 | /* Try again later. */ | |
463c84b9 | 182 | icsk->icsk_ack.blocked = 1; |
1da177e4 | 183 | NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKLOCKED); |
463c84b9 | 184 | sk_reset_timer(sk, &icsk->icsk_delack_timer, jiffies + TCP_DELACK_MIN); |
1da177e4 LT |
185 | goto out_unlock; |
186 | } | |
187 | ||
188 | sk_stream_mem_reclaim(sk); | |
189 | ||
463c84b9 | 190 | if (sk->sk_state == TCP_CLOSE || !(icsk->icsk_ack.pending & ICSK_ACK_TIMER)) |
1da177e4 LT |
191 | goto out; |
192 | ||
463c84b9 ACM |
193 | if (time_after(icsk->icsk_ack.timeout, jiffies)) { |
194 | sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout); | |
1da177e4 LT |
195 | goto out; |
196 | } | |
463c84b9 | 197 | icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER; |
1da177e4 | 198 | |
b03efcfb | 199 | if (!skb_queue_empty(&tp->ucopy.prequeue)) { |
1da177e4 LT |
200 | struct sk_buff *skb; |
201 | ||
b03efcfb | 202 | NET_INC_STATS_BH(LINUX_MIB_TCPSCHEDULERFAILED); |
1da177e4 LT |
203 | |
204 | while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) | |
205 | sk->sk_backlog_rcv(sk, skb); | |
206 | ||
207 | tp->ucopy.memory = 0; | |
208 | } | |
209 | ||
463c84b9 ACM |
210 | if (inet_csk_ack_scheduled(sk)) { |
211 | if (!icsk->icsk_ack.pingpong) { | |
1da177e4 | 212 | /* Delayed ACK missed: inflate ATO. */ |
463c84b9 | 213 | icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1, icsk->icsk_rto); |
1da177e4 LT |
214 | } else { |
215 | /* Delayed ACK missed: leave pingpong mode and | |
216 | * deflate ATO. | |
217 | */ | |
463c84b9 ACM |
218 | icsk->icsk_ack.pingpong = 0; |
219 | icsk->icsk_ack.ato = TCP_ATO_MIN; | |
1da177e4 LT |
220 | } |
221 | tcp_send_ack(sk); | |
222 | NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKS); | |
223 | } | |
224 | TCP_CHECK_TIMER(sk); | |
225 | ||
226 | out: | |
227 | if (tcp_memory_pressure) | |
228 | sk_stream_mem_reclaim(sk); | |
229 | out_unlock: | |
230 | bh_unlock_sock(sk); | |
231 | sock_put(sk); | |
232 | } | |
233 | ||
234 | static void tcp_probe_timer(struct sock *sk) | |
235 | { | |
6687e988 | 236 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
237 | struct tcp_sock *tp = tcp_sk(sk); |
238 | int max_probes; | |
239 | ||
240 | if (tp->packets_out || !sk->sk_send_head) { | |
6687e988 | 241 | icsk->icsk_probes_out = 0; |
1da177e4 LT |
242 | return; |
243 | } | |
244 | ||
245 | /* *WARNING* RFC 1122 forbids this | |
246 | * | |
247 | * It doesn't AFAIK, because we kill the retransmit timer -AK | |
248 | * | |
249 | * FIXME: We ought not to do it, Solaris 2.5 actually has fixing | |
250 | * this behaviour in Solaris down as a bug fix. [AC] | |
251 | * | |
6687e988 | 252 | * Let me to explain. icsk_probes_out is zeroed by incoming ACKs |
1da177e4 LT |
253 | * even if they advertise zero window. Hence, connection is killed only |
254 | * if we received no ACKs for normal connection timeout. It is not killed | |
255 | * only because window stays zero for some time, window may be zero | |
256 | * until armageddon and even later. We are in full accordance | |
257 | * with RFCs, only probe timer combines both retransmission timeout | |
258 | * and probe timeout in one bottle. --ANK | |
259 | */ | |
260 | max_probes = sysctl_tcp_retries2; | |
261 | ||
262 | if (sock_flag(sk, SOCK_DEAD)) { | |
463c84b9 | 263 | const int alive = ((icsk->icsk_rto << icsk->icsk_backoff) < TCP_RTO_MAX); |
1da177e4 LT |
264 | |
265 | max_probes = tcp_orphan_retries(sk, alive); | |
266 | ||
6687e988 | 267 | if (tcp_out_of_resources(sk, alive || icsk->icsk_probes_out <= max_probes)) |
1da177e4 LT |
268 | return; |
269 | } | |
270 | ||
6687e988 | 271 | if (icsk->icsk_probes_out > max_probes) { |
1da177e4 LT |
272 | tcp_write_err(sk); |
273 | } else { | |
274 | /* Only send another probe if we didn't close things up. */ | |
275 | tcp_send_probe0(sk); | |
276 | } | |
277 | } | |
278 | ||
279 | /* | |
280 | * The TCP retransmit timer. | |
281 | */ | |
282 | ||
283 | static void tcp_retransmit_timer(struct sock *sk) | |
284 | { | |
285 | struct tcp_sock *tp = tcp_sk(sk); | |
463c84b9 | 286 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
287 | |
288 | if (!tp->packets_out) | |
289 | goto out; | |
290 | ||
291 | BUG_TRAP(!skb_queue_empty(&sk->sk_write_queue)); | |
292 | ||
293 | if (!tp->snd_wnd && !sock_flag(sk, SOCK_DEAD) && | |
294 | !((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))) { | |
295 | /* Receiver dastardly shrinks window. Our retransmits | |
296 | * become zero probes, but we should not timeout this | |
297 | * connection. If the socket is an orphan, time it out, | |
298 | * we cannot allow such beasts to hang infinitely. | |
299 | */ | |
300 | #ifdef TCP_DEBUG | |
301 | if (net_ratelimit()) { | |
302 | struct inet_sock *inet = inet_sk(sk); | |
303 | printk(KERN_DEBUG "TCP: Treason uncloaked! Peer %u.%u.%u.%u:%u/%u shrinks window %u:%u. Repaired.\n", | |
304 | NIPQUAD(inet->daddr), htons(inet->dport), | |
305 | inet->num, tp->snd_una, tp->snd_nxt); | |
306 | } | |
307 | #endif | |
308 | if (tcp_time_stamp - tp->rcv_tstamp > TCP_RTO_MAX) { | |
309 | tcp_write_err(sk); | |
310 | goto out; | |
311 | } | |
312 | tcp_enter_loss(sk, 0); | |
313 | tcp_retransmit_skb(sk, skb_peek(&sk->sk_write_queue)); | |
314 | __sk_dst_reset(sk); | |
315 | goto out_reset_timer; | |
316 | } | |
317 | ||
318 | if (tcp_write_timeout(sk)) | |
319 | goto out; | |
320 | ||
463c84b9 | 321 | if (icsk->icsk_retransmits == 0) { |
6687e988 ACM |
322 | if (icsk->icsk_ca_state == TCP_CA_Disorder || |
323 | icsk->icsk_ca_state == TCP_CA_Recovery) { | |
1da177e4 | 324 | if (tp->rx_opt.sack_ok) { |
6687e988 | 325 | if (icsk->icsk_ca_state == TCP_CA_Recovery) |
1da177e4 LT |
326 | NET_INC_STATS_BH(LINUX_MIB_TCPSACKRECOVERYFAIL); |
327 | else | |
328 | NET_INC_STATS_BH(LINUX_MIB_TCPSACKFAILURES); | |
329 | } else { | |
6687e988 | 330 | if (icsk->icsk_ca_state == TCP_CA_Recovery) |
1da177e4 LT |
331 | NET_INC_STATS_BH(LINUX_MIB_TCPRENORECOVERYFAIL); |
332 | else | |
333 | NET_INC_STATS_BH(LINUX_MIB_TCPRENOFAILURES); | |
334 | } | |
6687e988 | 335 | } else if (icsk->icsk_ca_state == TCP_CA_Loss) { |
1da177e4 LT |
336 | NET_INC_STATS_BH(LINUX_MIB_TCPLOSSFAILURES); |
337 | } else { | |
338 | NET_INC_STATS_BH(LINUX_MIB_TCPTIMEOUTS); | |
339 | } | |
340 | } | |
341 | ||
342 | if (tcp_use_frto(sk)) { | |
343 | tcp_enter_frto(sk); | |
344 | } else { | |
345 | tcp_enter_loss(sk, 0); | |
346 | } | |
347 | ||
348 | if (tcp_retransmit_skb(sk, skb_peek(&sk->sk_write_queue)) > 0) { | |
349 | /* Retransmission failed because of local congestion, | |
350 | * do not backoff. | |
351 | */ | |
463c84b9 ACM |
352 | if (!icsk->icsk_retransmits) |
353 | icsk->icsk_retransmits = 1; | |
354 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, | |
3f421baa ACM |
355 | min(icsk->icsk_rto, TCP_RESOURCE_PROBE_INTERVAL), |
356 | TCP_RTO_MAX); | |
1da177e4 LT |
357 | goto out; |
358 | } | |
359 | ||
360 | /* Increase the timeout each time we retransmit. Note that | |
361 | * we do not increase the rtt estimate. rto is initialized | |
362 | * from rtt, but increases here. Jacobson (SIGCOMM 88) suggests | |
363 | * that doubling rto each time is the least we can get away with. | |
364 | * In KA9Q, Karn uses this for the first few times, and then | |
365 | * goes to quadratic. netBSD doubles, but only goes up to *64, | |
366 | * and clamps at 1 to 64 sec afterwards. Note that 120 sec is | |
367 | * defined in the protocol as the maximum possible RTT. I guess | |
368 | * we'll have to use something other than TCP to talk to the | |
369 | * University of Mars. | |
370 | * | |
371 | * PAWS allows us longer timeouts and large windows, so once | |
372 | * implemented ftp to mars will work nicely. We will have to fix | |
373 | * the 120 second clamps though! | |
374 | */ | |
463c84b9 ACM |
375 | icsk->icsk_backoff++; |
376 | icsk->icsk_retransmits++; | |
1da177e4 LT |
377 | |
378 | out_reset_timer: | |
463c84b9 | 379 | icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX); |
3f421baa | 380 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, TCP_RTO_MAX); |
463c84b9 | 381 | if (icsk->icsk_retransmits > sysctl_tcp_retries1) |
1da177e4 LT |
382 | __sk_dst_reset(sk); |
383 | ||
384 | out:; | |
385 | } | |
386 | ||
387 | static void tcp_write_timer(unsigned long data) | |
388 | { | |
389 | struct sock *sk = (struct sock*)data; | |
463c84b9 | 390 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
391 | int event; |
392 | ||
393 | bh_lock_sock(sk); | |
394 | if (sock_owned_by_user(sk)) { | |
395 | /* Try again later */ | |
463c84b9 | 396 | sk_reset_timer(sk, &icsk->icsk_retransmit_timer, jiffies + (HZ / 20)); |
1da177e4 LT |
397 | goto out_unlock; |
398 | } | |
399 | ||
463c84b9 | 400 | if (sk->sk_state == TCP_CLOSE || !icsk->icsk_pending) |
1da177e4 LT |
401 | goto out; |
402 | ||
463c84b9 ACM |
403 | if (time_after(icsk->icsk_timeout, jiffies)) { |
404 | sk_reset_timer(sk, &icsk->icsk_retransmit_timer, icsk->icsk_timeout); | |
1da177e4 LT |
405 | goto out; |
406 | } | |
407 | ||
463c84b9 ACM |
408 | event = icsk->icsk_pending; |
409 | icsk->icsk_pending = 0; | |
1da177e4 LT |
410 | |
411 | switch (event) { | |
463c84b9 | 412 | case ICSK_TIME_RETRANS: |
1da177e4 LT |
413 | tcp_retransmit_timer(sk); |
414 | break; | |
463c84b9 | 415 | case ICSK_TIME_PROBE0: |
1da177e4 LT |
416 | tcp_probe_timer(sk); |
417 | break; | |
418 | } | |
419 | TCP_CHECK_TIMER(sk); | |
420 | ||
421 | out: | |
422 | sk_stream_mem_reclaim(sk); | |
423 | out_unlock: | |
424 | bh_unlock_sock(sk); | |
425 | sock_put(sk); | |
426 | } | |
427 | ||
295f7324 ACM |
428 | /* |
429 | * Timer for listening sockets | |
430 | */ | |
431 | ||
432 | static void tcp_synack_timer(struct sock *sk) | |
433 | { | |
a019d6fe ACM |
434 | inet_csk_reqsk_queue_prune(sk, TCP_SYNQ_INTERVAL, |
435 | TCP_TIMEOUT_INIT, TCP_RTO_MAX); | |
1da177e4 LT |
436 | } |
437 | ||
1da177e4 LT |
438 | void tcp_set_keepalive(struct sock *sk, int val) |
439 | { | |
440 | if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) | |
441 | return; | |
442 | ||
443 | if (val && !sock_flag(sk, SOCK_KEEPOPEN)) | |
463c84b9 | 444 | inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tcp_sk(sk))); |
1da177e4 | 445 | else if (!val) |
463c84b9 | 446 | inet_csk_delete_keepalive_timer(sk); |
1da177e4 LT |
447 | } |
448 | ||
449 | ||
450 | static void tcp_keepalive_timer (unsigned long data) | |
451 | { | |
452 | struct sock *sk = (struct sock *) data; | |
6687e988 | 453 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
454 | struct tcp_sock *tp = tcp_sk(sk); |
455 | __u32 elapsed; | |
456 | ||
457 | /* Only process if socket is not in use. */ | |
458 | bh_lock_sock(sk); | |
459 | if (sock_owned_by_user(sk)) { | |
460 | /* Try again later. */ | |
463c84b9 | 461 | inet_csk_reset_keepalive_timer (sk, HZ/20); |
1da177e4 LT |
462 | goto out; |
463 | } | |
464 | ||
465 | if (sk->sk_state == TCP_LISTEN) { | |
466 | tcp_synack_timer(sk); | |
467 | goto out; | |
468 | } | |
469 | ||
470 | if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) { | |
471 | if (tp->linger2 >= 0) { | |
463c84b9 | 472 | const int tmo = tcp_fin_time(sk) - TCP_TIMEWAIT_LEN; |
1da177e4 LT |
473 | |
474 | if (tmo > 0) { | |
475 | tcp_time_wait(sk, TCP_FIN_WAIT2, tmo); | |
476 | goto out; | |
477 | } | |
478 | } | |
479 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
480 | goto death; | |
481 | } | |
482 | ||
483 | if (!sock_flag(sk, SOCK_KEEPOPEN) || sk->sk_state == TCP_CLOSE) | |
484 | goto out; | |
485 | ||
486 | elapsed = keepalive_time_when(tp); | |
487 | ||
488 | /* It is alive without keepalive 8) */ | |
489 | if (tp->packets_out || sk->sk_send_head) | |
490 | goto resched; | |
491 | ||
492 | elapsed = tcp_time_stamp - tp->rcv_tstamp; | |
493 | ||
494 | if (elapsed >= keepalive_time_when(tp)) { | |
6687e988 ACM |
495 | if ((!tp->keepalive_probes && icsk->icsk_probes_out >= sysctl_tcp_keepalive_probes) || |
496 | (tp->keepalive_probes && icsk->icsk_probes_out >= tp->keepalive_probes)) { | |
1da177e4 LT |
497 | tcp_send_active_reset(sk, GFP_ATOMIC); |
498 | tcp_write_err(sk); | |
499 | goto out; | |
500 | } | |
501 | if (tcp_write_wakeup(sk) <= 0) { | |
6687e988 | 502 | icsk->icsk_probes_out++; |
1da177e4 LT |
503 | elapsed = keepalive_intvl_when(tp); |
504 | } else { | |
505 | /* If keepalive was lost due to local congestion, | |
506 | * try harder. | |
507 | */ | |
508 | elapsed = TCP_RESOURCE_PROBE_INTERVAL; | |
509 | } | |
510 | } else { | |
511 | /* It is tp->rcv_tstamp + keepalive_time_when(tp) */ | |
512 | elapsed = keepalive_time_when(tp) - elapsed; | |
513 | } | |
514 | ||
515 | TCP_CHECK_TIMER(sk); | |
516 | sk_stream_mem_reclaim(sk); | |
517 | ||
518 | resched: | |
463c84b9 | 519 | inet_csk_reset_keepalive_timer (sk, elapsed); |
1da177e4 LT |
520 | goto out; |
521 | ||
522 | death: | |
523 | tcp_done(sk); | |
524 | ||
525 | out: | |
526 | bh_unlock_sock(sk); | |
527 | sock_put(sk); | |
528 | } |