Commit | Line | Data |
---|---|---|
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 | ||
ab32ea5d BH |
26 | int sysctl_tcp_syn_retries __read_mostly = TCP_SYN_RETRIES; |
27 | int sysctl_tcp_synack_retries __read_mostly = TCP_SYNACK_RETRIES; | |
28 | int sysctl_tcp_keepalive_time __read_mostly = TCP_KEEPALIVE_TIME; | |
29 | int sysctl_tcp_keepalive_probes __read_mostly = TCP_KEEPALIVE_PROBES; | |
30 | int sysctl_tcp_keepalive_intvl __read_mostly = TCP_KEEPALIVE_INTVL; | |
31 | int sysctl_tcp_retries1 __read_mostly = TCP_RETR1; | |
32 | int sysctl_tcp_retries2 __read_mostly = TCP_RETR2; | |
33 | int sysctl_tcp_orphan_retries __read_mostly; | |
1da177e4 LT |
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 | * | |
caa20d9a | 61 | * Criteria is still not confirmed experimentally and may change. |
1da177e4 LT |
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 | ||
e905a9ed | 72 | /* If peer does not open window for long time, or did not transmit |
1da177e4 LT |
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 | ||
e4fd5da3 | 81 | if (tcp_too_many_orphans(sk, orphans)) { |
1da177e4 LT |
82 | if (net_ratelimit()) |
83 | printk(KERN_INFO "Out of socket memory\n"); | |
84 | ||
85 | /* Catch exceptional cases, when connection requires reset. | |
86 | * 1. Last segment was sent recently. */ | |
87 | if ((s32)(tcp_time_stamp - tp->lsndtime) <= TCP_TIMEWAIT_LEN || | |
88 | /* 2. Window is closed. */ | |
89 | (!tp->snd_wnd && !tp->packets_out)) | |
90 | do_reset = 1; | |
91 | if (do_reset) | |
92 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
93 | tcp_done(sk); | |
94 | NET_INC_STATS_BH(LINUX_MIB_TCPABORTONMEMORY); | |
95 | return 1; | |
96 | } | |
97 | return 0; | |
98 | } | |
99 | ||
100 | /* Calculate maximal number or retries on an orphaned socket. */ | |
101 | static int tcp_orphan_retries(struct sock *sk, int alive) | |
102 | { | |
103 | int retries = sysctl_tcp_orphan_retries; /* May be zero. */ | |
104 | ||
105 | /* We know from an ICMP that something is wrong. */ | |
106 | if (sk->sk_err_soft && !alive) | |
107 | retries = 0; | |
108 | ||
109 | /* However, if socket sent something recently, select some safe | |
110 | * number of retries. 8 corresponds to >100 seconds with minimal | |
111 | * RTO of 200msec. */ | |
112 | if (retries == 0 && alive) | |
113 | retries = 8; | |
114 | return retries; | |
115 | } | |
116 | ||
ce55dd36 ED |
117 | static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk) |
118 | { | |
119 | int mss; | |
120 | ||
121 | /* Black hole detection */ | |
122 | if (sysctl_tcp_mtu_probing) { | |
123 | if (!icsk->icsk_mtup.enabled) { | |
124 | icsk->icsk_mtup.enabled = 1; | |
125 | tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); | |
126 | } else { | |
127 | struct tcp_sock *tp = tcp_sk(sk); | |
128 | mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)/2; | |
129 | mss = min(sysctl_tcp_base_mss, mss); | |
130 | mss = max(mss, 68 - tp->tcp_header_len); | |
131 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); | |
132 | tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); | |
133 | } | |
134 | } | |
135 | } | |
136 | ||
1da177e4 LT |
137 | /* A write timeout has occurred. Process the after effects. */ |
138 | static int tcp_write_timeout(struct sock *sk) | |
139 | { | |
5d424d5a | 140 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
141 | int retry_until; |
142 | ||
143 | if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { | |
463c84b9 | 144 | if (icsk->icsk_retransmits) |
1da177e4 | 145 | dst_negative_advice(&sk->sk_dst_cache); |
463c84b9 | 146 | retry_until = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries; |
1da177e4 | 147 | } else { |
463c84b9 | 148 | if (icsk->icsk_retransmits >= sysctl_tcp_retries1) { |
5d424d5a | 149 | /* Black hole detection */ |
ce55dd36 | 150 | tcp_mtu_probing(icsk, sk); |
1da177e4 LT |
151 | |
152 | dst_negative_advice(&sk->sk_dst_cache); | |
153 | } | |
154 | ||
155 | retry_until = sysctl_tcp_retries2; | |
156 | if (sock_flag(sk, SOCK_DEAD)) { | |
463c84b9 | 157 | const int alive = (icsk->icsk_rto < TCP_RTO_MAX); |
e905a9ed | 158 | |
1da177e4 LT |
159 | retry_until = tcp_orphan_retries(sk, alive); |
160 | ||
463c84b9 | 161 | if (tcp_out_of_resources(sk, alive || icsk->icsk_retransmits < retry_until)) |
1da177e4 LT |
162 | return 1; |
163 | } | |
164 | } | |
165 | ||
463c84b9 | 166 | if (icsk->icsk_retransmits >= retry_until) { |
1da177e4 LT |
167 | /* Has it gone just too far? */ |
168 | tcp_write_err(sk); | |
169 | return 1; | |
170 | } | |
171 | return 0; | |
172 | } | |
173 | ||
174 | static void tcp_delack_timer(unsigned long data) | |
175 | { | |
176 | struct sock *sk = (struct sock*)data; | |
177 | struct tcp_sock *tp = tcp_sk(sk); | |
463c84b9 | 178 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
179 | |
180 | bh_lock_sock(sk); | |
181 | if (sock_owned_by_user(sk)) { | |
182 | /* Try again later. */ | |
463c84b9 | 183 | icsk->icsk_ack.blocked = 1; |
1da177e4 | 184 | NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKLOCKED); |
463c84b9 | 185 | sk_reset_timer(sk, &icsk->icsk_delack_timer, jiffies + TCP_DELACK_MIN); |
1da177e4 LT |
186 | goto out_unlock; |
187 | } | |
188 | ||
189 | sk_stream_mem_reclaim(sk); | |
190 | ||
463c84b9 | 191 | if (sk->sk_state == TCP_CLOSE || !(icsk->icsk_ack.pending & ICSK_ACK_TIMER)) |
1da177e4 LT |
192 | goto out; |
193 | ||
463c84b9 ACM |
194 | if (time_after(icsk->icsk_ack.timeout, jiffies)) { |
195 | sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout); | |
1da177e4 LT |
196 | goto out; |
197 | } | |
463c84b9 | 198 | icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER; |
1da177e4 | 199 | |
b03efcfb | 200 | if (!skb_queue_empty(&tp->ucopy.prequeue)) { |
1da177e4 LT |
201 | struct sk_buff *skb; |
202 | ||
b03efcfb | 203 | NET_INC_STATS_BH(LINUX_MIB_TCPSCHEDULERFAILED); |
1da177e4 LT |
204 | |
205 | while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) | |
206 | sk->sk_backlog_rcv(sk, skb); | |
207 | ||
208 | tp->ucopy.memory = 0; | |
209 | } | |
210 | ||
463c84b9 ACM |
211 | if (inet_csk_ack_scheduled(sk)) { |
212 | if (!icsk->icsk_ack.pingpong) { | |
1da177e4 | 213 | /* Delayed ACK missed: inflate ATO. */ |
463c84b9 | 214 | icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1, icsk->icsk_rto); |
1da177e4 LT |
215 | } else { |
216 | /* Delayed ACK missed: leave pingpong mode and | |
217 | * deflate ATO. | |
218 | */ | |
463c84b9 ACM |
219 | icsk->icsk_ack.pingpong = 0; |
220 | icsk->icsk_ack.ato = TCP_ATO_MIN; | |
1da177e4 LT |
221 | } |
222 | tcp_send_ack(sk); | |
223 | NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKS); | |
224 | } | |
225 | TCP_CHECK_TIMER(sk); | |
226 | ||
227 | out: | |
228 | if (tcp_memory_pressure) | |
229 | sk_stream_mem_reclaim(sk); | |
230 | out_unlock: | |
231 | bh_unlock_sock(sk); | |
232 | sock_put(sk); | |
233 | } | |
234 | ||
235 | static void tcp_probe_timer(struct sock *sk) | |
236 | { | |
6687e988 | 237 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
238 | struct tcp_sock *tp = tcp_sk(sk); |
239 | int max_probes; | |
240 | ||
fe067e8a | 241 | if (tp->packets_out || !tcp_send_head(sk)) { |
6687e988 | 242 | icsk->icsk_probes_out = 0; |
1da177e4 LT |
243 | return; |
244 | } | |
245 | ||
246 | /* *WARNING* RFC 1122 forbids this | |
247 | * | |
248 | * It doesn't AFAIK, because we kill the retransmit timer -AK | |
249 | * | |
250 | * FIXME: We ought not to do it, Solaris 2.5 actually has fixing | |
251 | * this behaviour in Solaris down as a bug fix. [AC] | |
252 | * | |
6687e988 | 253 | * Let me to explain. icsk_probes_out is zeroed by incoming ACKs |
1da177e4 LT |
254 | * even if they advertise zero window. Hence, connection is killed only |
255 | * if we received no ACKs for normal connection timeout. It is not killed | |
256 | * only because window stays zero for some time, window may be zero | |
257 | * until armageddon and even later. We are in full accordance | |
258 | * with RFCs, only probe timer combines both retransmission timeout | |
259 | * and probe timeout in one bottle. --ANK | |
260 | */ | |
261 | max_probes = sysctl_tcp_retries2; | |
262 | ||
263 | if (sock_flag(sk, SOCK_DEAD)) { | |
463c84b9 | 264 | const int alive = ((icsk->icsk_rto << icsk->icsk_backoff) < TCP_RTO_MAX); |
e905a9ed | 265 | |
1da177e4 LT |
266 | max_probes = tcp_orphan_retries(sk, alive); |
267 | ||
6687e988 | 268 | if (tcp_out_of_resources(sk, alive || icsk->icsk_probes_out <= max_probes)) |
1da177e4 LT |
269 | return; |
270 | } | |
271 | ||
6687e988 | 272 | if (icsk->icsk_probes_out > max_probes) { |
1da177e4 LT |
273 | tcp_write_err(sk); |
274 | } else { | |
275 | /* Only send another probe if we didn't close things up. */ | |
276 | tcp_send_probe0(sk); | |
277 | } | |
278 | } | |
279 | ||
280 | /* | |
281 | * The TCP retransmit timer. | |
282 | */ | |
283 | ||
284 | static void tcp_retransmit_timer(struct sock *sk) | |
285 | { | |
286 | struct tcp_sock *tp = tcp_sk(sk); | |
463c84b9 | 287 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
288 | |
289 | if (!tp->packets_out) | |
290 | goto out; | |
291 | ||
fe067e8a | 292 | BUG_TRAP(!tcp_write_queue_empty(sk)); |
1da177e4 LT |
293 | |
294 | if (!tp->snd_wnd && !sock_flag(sk, SOCK_DEAD) && | |
295 | !((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))) { | |
296 | /* Receiver dastardly shrinks window. Our retransmits | |
297 | * become zero probes, but we should not timeout this | |
298 | * connection. If the socket is an orphan, time it out, | |
299 | * we cannot allow such beasts to hang infinitely. | |
300 | */ | |
301 | #ifdef TCP_DEBUG | |
274707cf | 302 | if (1) { |
1da177e4 | 303 | struct inet_sock *inet = inet_sk(sk); |
274707cf | 304 | LIMIT_NETDEBUG(KERN_DEBUG "TCP: Treason uncloaked! Peer %u.%u.%u.%u:%u/%u shrinks window %u:%u. Repaired.\n", |
714e85be | 305 | NIPQUAD(inet->daddr), ntohs(inet->dport), |
1da177e4 LT |
306 | inet->num, tp->snd_una, tp->snd_nxt); |
307 | } | |
308 | #endif | |
309 | if (tcp_time_stamp - tp->rcv_tstamp > TCP_RTO_MAX) { | |
310 | tcp_write_err(sk); | |
311 | goto out; | |
312 | } | |
313 | tcp_enter_loss(sk, 0); | |
fe067e8a | 314 | tcp_retransmit_skb(sk, tcp_write_queue_head(sk)); |
1da177e4 LT |
315 | __sk_dst_reset(sk); |
316 | goto out_reset_timer; | |
317 | } | |
318 | ||
319 | if (tcp_write_timeout(sk)) | |
320 | goto out; | |
321 | ||
463c84b9 | 322 | if (icsk->icsk_retransmits == 0) { |
6687e988 ACM |
323 | if (icsk->icsk_ca_state == TCP_CA_Disorder || |
324 | icsk->icsk_ca_state == TCP_CA_Recovery) { | |
e60402d0 | 325 | if (tcp_is_sack(tp)) { |
6687e988 | 326 | if (icsk->icsk_ca_state == TCP_CA_Recovery) |
1da177e4 LT |
327 | NET_INC_STATS_BH(LINUX_MIB_TCPSACKRECOVERYFAIL); |
328 | else | |
329 | NET_INC_STATS_BH(LINUX_MIB_TCPSACKFAILURES); | |
330 | } else { | |
6687e988 | 331 | if (icsk->icsk_ca_state == TCP_CA_Recovery) |
1da177e4 LT |
332 | NET_INC_STATS_BH(LINUX_MIB_TCPRENORECOVERYFAIL); |
333 | else | |
334 | NET_INC_STATS_BH(LINUX_MIB_TCPRENOFAILURES); | |
335 | } | |
6687e988 | 336 | } else if (icsk->icsk_ca_state == TCP_CA_Loss) { |
1da177e4 LT |
337 | NET_INC_STATS_BH(LINUX_MIB_TCPLOSSFAILURES); |
338 | } else { | |
339 | NET_INC_STATS_BH(LINUX_MIB_TCPTIMEOUTS); | |
340 | } | |
341 | } | |
342 | ||
343 | if (tcp_use_frto(sk)) { | |
344 | tcp_enter_frto(sk); | |
345 | } else { | |
346 | tcp_enter_loss(sk, 0); | |
347 | } | |
348 | ||
fe067e8a | 349 | if (tcp_retransmit_skb(sk, tcp_write_queue_head(sk)) > 0) { |
1da177e4 LT |
350 | /* Retransmission failed because of local congestion, |
351 | * do not backoff. | |
352 | */ | |
463c84b9 ACM |
353 | if (!icsk->icsk_retransmits) |
354 | icsk->icsk_retransmits = 1; | |
355 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, | |
3f421baa ACM |
356 | min(icsk->icsk_rto, TCP_RESOURCE_PROBE_INTERVAL), |
357 | TCP_RTO_MAX); | |
1da177e4 LT |
358 | goto out; |
359 | } | |
360 | ||
361 | /* Increase the timeout each time we retransmit. Note that | |
362 | * we do not increase the rtt estimate. rto is initialized | |
363 | * from rtt, but increases here. Jacobson (SIGCOMM 88) suggests | |
364 | * that doubling rto each time is the least we can get away with. | |
365 | * In KA9Q, Karn uses this for the first few times, and then | |
366 | * goes to quadratic. netBSD doubles, but only goes up to *64, | |
367 | * and clamps at 1 to 64 sec afterwards. Note that 120 sec is | |
368 | * defined in the protocol as the maximum possible RTT. I guess | |
369 | * we'll have to use something other than TCP to talk to the | |
370 | * University of Mars. | |
371 | * | |
372 | * PAWS allows us longer timeouts and large windows, so once | |
373 | * implemented ftp to mars will work nicely. We will have to fix | |
374 | * the 120 second clamps though! | |
375 | */ | |
463c84b9 ACM |
376 | icsk->icsk_backoff++; |
377 | icsk->icsk_retransmits++; | |
1da177e4 LT |
378 | |
379 | out_reset_timer: | |
463c84b9 | 380 | icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX); |
3f421baa | 381 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, TCP_RTO_MAX); |
463c84b9 | 382 | if (icsk->icsk_retransmits > sysctl_tcp_retries1) |
1da177e4 LT |
383 | __sk_dst_reset(sk); |
384 | ||
385 | out:; | |
386 | } | |
387 | ||
388 | static void tcp_write_timer(unsigned long data) | |
389 | { | |
390 | struct sock *sk = (struct sock*)data; | |
463c84b9 | 391 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
392 | int event; |
393 | ||
394 | bh_lock_sock(sk); | |
395 | if (sock_owned_by_user(sk)) { | |
396 | /* Try again later */ | |
463c84b9 | 397 | sk_reset_timer(sk, &icsk->icsk_retransmit_timer, jiffies + (HZ / 20)); |
1da177e4 LT |
398 | goto out_unlock; |
399 | } | |
400 | ||
463c84b9 | 401 | if (sk->sk_state == TCP_CLOSE || !icsk->icsk_pending) |
1da177e4 LT |
402 | goto out; |
403 | ||
463c84b9 ACM |
404 | if (time_after(icsk->icsk_timeout, jiffies)) { |
405 | sk_reset_timer(sk, &icsk->icsk_retransmit_timer, icsk->icsk_timeout); | |
1da177e4 LT |
406 | goto out; |
407 | } | |
408 | ||
463c84b9 ACM |
409 | event = icsk->icsk_pending; |
410 | icsk->icsk_pending = 0; | |
1da177e4 LT |
411 | |
412 | switch (event) { | |
463c84b9 | 413 | case ICSK_TIME_RETRANS: |
1da177e4 LT |
414 | tcp_retransmit_timer(sk); |
415 | break; | |
463c84b9 | 416 | case ICSK_TIME_PROBE0: |
1da177e4 LT |
417 | tcp_probe_timer(sk); |
418 | break; | |
419 | } | |
420 | TCP_CHECK_TIMER(sk); | |
421 | ||
422 | out: | |
423 | sk_stream_mem_reclaim(sk); | |
424 | out_unlock: | |
425 | bh_unlock_sock(sk); | |
426 | sock_put(sk); | |
427 | } | |
428 | ||
295f7324 ACM |
429 | /* |
430 | * Timer for listening sockets | |
431 | */ | |
432 | ||
433 | static void tcp_synack_timer(struct sock *sk) | |
434 | { | |
a019d6fe ACM |
435 | inet_csk_reqsk_queue_prune(sk, TCP_SYNQ_INTERVAL, |
436 | TCP_TIMEOUT_INIT, TCP_RTO_MAX); | |
1da177e4 LT |
437 | } |
438 | ||
1da177e4 LT |
439 | void tcp_set_keepalive(struct sock *sk, int val) |
440 | { | |
441 | if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) | |
442 | return; | |
443 | ||
444 | if (val && !sock_flag(sk, SOCK_KEEPOPEN)) | |
463c84b9 | 445 | inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tcp_sk(sk))); |
1da177e4 | 446 | else if (!val) |
463c84b9 | 447 | inet_csk_delete_keepalive_timer(sk); |
1da177e4 LT |
448 | } |
449 | ||
450 | ||
451 | static void tcp_keepalive_timer (unsigned long data) | |
452 | { | |
453 | struct sock *sk = (struct sock *) data; | |
6687e988 | 454 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
455 | struct tcp_sock *tp = tcp_sk(sk); |
456 | __u32 elapsed; | |
457 | ||
458 | /* Only process if socket is not in use. */ | |
459 | bh_lock_sock(sk); | |
460 | if (sock_owned_by_user(sk)) { | |
e905a9ed | 461 | /* Try again later. */ |
463c84b9 | 462 | inet_csk_reset_keepalive_timer (sk, HZ/20); |
1da177e4 LT |
463 | goto out; |
464 | } | |
465 | ||
466 | if (sk->sk_state == TCP_LISTEN) { | |
467 | tcp_synack_timer(sk); | |
468 | goto out; | |
469 | } | |
470 | ||
471 | if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) { | |
472 | if (tp->linger2 >= 0) { | |
463c84b9 | 473 | const int tmo = tcp_fin_time(sk) - TCP_TIMEWAIT_LEN; |
1da177e4 LT |
474 | |
475 | if (tmo > 0) { | |
476 | tcp_time_wait(sk, TCP_FIN_WAIT2, tmo); | |
477 | goto out; | |
478 | } | |
479 | } | |
480 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
481 | goto death; | |
482 | } | |
483 | ||
484 | if (!sock_flag(sk, SOCK_KEEPOPEN) || sk->sk_state == TCP_CLOSE) | |
485 | goto out; | |
486 | ||
487 | elapsed = keepalive_time_when(tp); | |
488 | ||
489 | /* It is alive without keepalive 8) */ | |
fe067e8a | 490 | if (tp->packets_out || tcp_send_head(sk)) |
1da177e4 LT |
491 | goto resched; |
492 | ||
493 | elapsed = tcp_time_stamp - tp->rcv_tstamp; | |
494 | ||
495 | if (elapsed >= keepalive_time_when(tp)) { | |
6687e988 ACM |
496 | if ((!tp->keepalive_probes && icsk->icsk_probes_out >= sysctl_tcp_keepalive_probes) || |
497 | (tp->keepalive_probes && icsk->icsk_probes_out >= tp->keepalive_probes)) { | |
1da177e4 LT |
498 | tcp_send_active_reset(sk, GFP_ATOMIC); |
499 | tcp_write_err(sk); | |
500 | goto out; | |
501 | } | |
502 | if (tcp_write_wakeup(sk) <= 0) { | |
6687e988 | 503 | icsk->icsk_probes_out++; |
1da177e4 LT |
504 | elapsed = keepalive_intvl_when(tp); |
505 | } else { | |
506 | /* If keepalive was lost due to local congestion, | |
507 | * try harder. | |
508 | */ | |
509 | elapsed = TCP_RESOURCE_PROBE_INTERVAL; | |
510 | } | |
511 | } else { | |
512 | /* It is tp->rcv_tstamp + keepalive_time_when(tp) */ | |
513 | elapsed = keepalive_time_when(tp) - elapsed; | |
514 | } | |
515 | ||
516 | TCP_CHECK_TIMER(sk); | |
517 | sk_stream_mem_reclaim(sk); | |
518 | ||
519 | resched: | |
463c84b9 | 520 | inet_csk_reset_keepalive_timer (sk, elapsed); |
1da177e4 LT |
521 | goto out; |
522 | ||
e905a9ed | 523 | death: |
1da177e4 LT |
524 | tcp_done(sk); |
525 | ||
526 | out: | |
527 | bh_unlock_sock(sk); | |
528 | sock_put(sk); | |
529 | } |