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 | * | |
02c30a84 | 8 | * Authors: Ross Biro |
1da177e4 LT |
9 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
10 | * Mark Evans, <evansmp@uhura.aston.ac.uk> | |
11 | * Corey Minyard <wf-rch!minyard@relay.EU.net> | |
12 | * Florian La Roche, <flla@stud.uni-sb.de> | |
13 | * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> | |
14 | * Linus Torvalds, <torvalds@cs.helsinki.fi> | |
15 | * Alan Cox, <gw4pts@gw4pts.ampr.org> | |
16 | * Matthew Dillon, <dillon@apollo.west.oic.com> | |
17 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> | |
18 | * Jorge Cwik, <jorge@laser.satlink.net> | |
19 | */ | |
20 | ||
21 | #include <linux/module.h> | |
22 | #include <net/tcp.h> | |
23 | ||
ab32ea5d BH |
24 | int sysctl_tcp_syn_retries __read_mostly = TCP_SYN_RETRIES; |
25 | int sysctl_tcp_synack_retries __read_mostly = TCP_SYNACK_RETRIES; | |
26 | int sysctl_tcp_keepalive_time __read_mostly = TCP_KEEPALIVE_TIME; | |
27 | int sysctl_tcp_keepalive_probes __read_mostly = TCP_KEEPALIVE_PROBES; | |
28 | int sysctl_tcp_keepalive_intvl __read_mostly = TCP_KEEPALIVE_INTVL; | |
29 | int sysctl_tcp_retries1 __read_mostly = TCP_RETR1; | |
30 | int sysctl_tcp_retries2 __read_mostly = TCP_RETR2; | |
31 | int sysctl_tcp_orphan_retries __read_mostly; | |
1da177e4 LT |
32 | |
33 | static void tcp_write_timer(unsigned long); | |
34 | static void tcp_delack_timer(unsigned long); | |
35 | static void tcp_keepalive_timer (unsigned long data); | |
36 | ||
463c84b9 ACM |
37 | void tcp_init_xmit_timers(struct sock *sk) |
38 | { | |
39 | inet_csk_init_xmit_timers(sk, &tcp_write_timer, &tcp_delack_timer, | |
40 | &tcp_keepalive_timer); | |
41 | } | |
42 | ||
3f421baa ACM |
43 | EXPORT_SYMBOL(tcp_init_xmit_timers); |
44 | ||
1da177e4 LT |
45 | static void tcp_write_err(struct sock *sk) |
46 | { | |
47 | sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT; | |
48 | sk->sk_error_report(sk); | |
49 | ||
50 | tcp_done(sk); | |
de0744af | 51 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONTIMEOUT); |
1da177e4 LT |
52 | } |
53 | ||
54 | /* Do not allow orphaned sockets to eat all our resources. | |
55 | * This is direct violation of TCP specs, but it is required | |
56 | * to prevent DoS attacks. It is called when a retransmission timeout | |
57 | * or zero probe timeout occurs on orphaned socket. | |
58 | * | |
caa20d9a | 59 | * Criteria is still not confirmed experimentally and may change. |
1da177e4 LT |
60 | * We kill the socket, if: |
61 | * 1. If number of orphaned sockets exceeds an administratively configured | |
62 | * limit. | |
63 | * 2. If we have strong memory pressure. | |
64 | */ | |
65 | static int tcp_out_of_resources(struct sock *sk, int do_reset) | |
66 | { | |
67 | struct tcp_sock *tp = tcp_sk(sk); | |
dd24c001 | 68 | int orphans = percpu_counter_read_positive(&tcp_orphan_count); |
1da177e4 | 69 | |
e905a9ed | 70 | /* If peer does not open window for long time, or did not transmit |
1da177e4 LT |
71 | * anything for long time, penalize it. */ |
72 | if ((s32)(tcp_time_stamp - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset) | |
73 | orphans <<= 1; | |
74 | ||
75 | /* If some dubious ICMP arrived, penalize even more. */ | |
76 | if (sk->sk_err_soft) | |
77 | orphans <<= 1; | |
78 | ||
e4fd5da3 | 79 | if (tcp_too_many_orphans(sk, orphans)) { |
1da177e4 LT |
80 | if (net_ratelimit()) |
81 | printk(KERN_INFO "Out of socket memory\n"); | |
82 | ||
83 | /* Catch exceptional cases, when connection requires reset. | |
84 | * 1. Last segment was sent recently. */ | |
85 | if ((s32)(tcp_time_stamp - tp->lsndtime) <= TCP_TIMEWAIT_LEN || | |
86 | /* 2. Window is closed. */ | |
87 | (!tp->snd_wnd && !tp->packets_out)) | |
88 | do_reset = 1; | |
89 | if (do_reset) | |
90 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
91 | tcp_done(sk); | |
de0744af | 92 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY); |
1da177e4 LT |
93 | return 1; |
94 | } | |
95 | return 0; | |
96 | } | |
97 | ||
98 | /* Calculate maximal number or retries on an orphaned socket. */ | |
99 | static int tcp_orphan_retries(struct sock *sk, int alive) | |
100 | { | |
101 | int retries = sysctl_tcp_orphan_retries; /* May be zero. */ | |
102 | ||
103 | /* We know from an ICMP that something is wrong. */ | |
104 | if (sk->sk_err_soft && !alive) | |
105 | retries = 0; | |
106 | ||
107 | /* However, if socket sent something recently, select some safe | |
108 | * number of retries. 8 corresponds to >100 seconds with minimal | |
109 | * RTO of 200msec. */ | |
110 | if (retries == 0 && alive) | |
111 | retries = 8; | |
112 | return retries; | |
113 | } | |
114 | ||
ce55dd36 ED |
115 | static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk) |
116 | { | |
ce55dd36 ED |
117 | /* Black hole detection */ |
118 | if (sysctl_tcp_mtu_probing) { | |
119 | if (!icsk->icsk_mtup.enabled) { | |
120 | icsk->icsk_mtup.enabled = 1; | |
121 | tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); | |
122 | } else { | |
123 | struct tcp_sock *tp = tcp_sk(sk); | |
829942c1 DM |
124 | int mss; |
125 | ||
8beb5c5f | 126 | mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1; |
ce55dd36 ED |
127 | mss = min(sysctl_tcp_base_mss, mss); |
128 | mss = max(mss, 68 - tp->tcp_header_len); | |
129 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); | |
130 | tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); | |
131 | } | |
132 | } | |
133 | } | |
134 | ||
2f7de571 DL |
135 | /* This function calculates a "timeout" which is equivalent to the timeout of a |
136 | * TCP connection after "boundary" unsucessful, exponentially backed-off | |
137 | * retransmissions with an initial RTO of TCP_RTO_MIN. | |
138 | */ | |
139 | static bool retransmits_timed_out(struct sock *sk, | |
140 | unsigned int boundary) | |
141 | { | |
142 | unsigned int timeout, linear_backoff_thresh; | |
143 | unsigned int start_ts; | |
144 | ||
145 | if (!inet_csk(sk)->icsk_retransmits) | |
146 | return false; | |
147 | ||
148 | if (unlikely(!tcp_sk(sk)->retrans_stamp)) | |
149 | start_ts = TCP_SKB_CB(tcp_write_queue_head(sk))->when; | |
150 | else | |
151 | start_ts = tcp_sk(sk)->retrans_stamp; | |
152 | ||
153 | linear_backoff_thresh = ilog2(TCP_RTO_MAX/TCP_RTO_MIN); | |
154 | ||
155 | if (boundary <= linear_backoff_thresh) | |
156 | timeout = ((2 << boundary) - 1) * TCP_RTO_MIN; | |
157 | else | |
158 | timeout = ((2 << linear_backoff_thresh) - 1) * TCP_RTO_MIN + | |
159 | (boundary - linear_backoff_thresh) * TCP_RTO_MAX; | |
160 | ||
161 | return (tcp_time_stamp - start_ts) >= timeout; | |
162 | } | |
163 | ||
1da177e4 LT |
164 | /* A write timeout has occurred. Process the after effects. */ |
165 | static int tcp_write_timeout(struct sock *sk) | |
166 | { | |
5d424d5a | 167 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 168 | int retry_until; |
6fa12c85 | 169 | bool do_reset; |
1da177e4 LT |
170 | |
171 | if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { | |
463c84b9 | 172 | if (icsk->icsk_retransmits) |
ea94ff3b | 173 | dst_negative_advice(&sk->sk_dst_cache, sk); |
463c84b9 | 174 | retry_until = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries; |
1da177e4 | 175 | } else { |
6fa12c85 | 176 | if (retransmits_timed_out(sk, sysctl_tcp_retries1)) { |
5d424d5a | 177 | /* Black hole detection */ |
ce55dd36 | 178 | tcp_mtu_probing(icsk, sk); |
1da177e4 | 179 | |
ea94ff3b | 180 | dst_negative_advice(&sk->sk_dst_cache, sk); |
1da177e4 LT |
181 | } |
182 | ||
183 | retry_until = sysctl_tcp_retries2; | |
184 | if (sock_flag(sk, SOCK_DEAD)) { | |
463c84b9 | 185 | const int alive = (icsk->icsk_rto < TCP_RTO_MAX); |
e905a9ed | 186 | |
1da177e4 | 187 | retry_until = tcp_orphan_retries(sk, alive); |
6fa12c85 DL |
188 | do_reset = alive || |
189 | !retransmits_timed_out(sk, retry_until); | |
1da177e4 | 190 | |
6fa12c85 | 191 | if (tcp_out_of_resources(sk, do_reset)) |
1da177e4 LT |
192 | return 1; |
193 | } | |
194 | } | |
195 | ||
6fa12c85 | 196 | if (retransmits_timed_out(sk, retry_until)) { |
1da177e4 LT |
197 | /* Has it gone just too far? */ |
198 | tcp_write_err(sk); | |
199 | return 1; | |
200 | } | |
201 | return 0; | |
202 | } | |
203 | ||
204 | static void tcp_delack_timer(unsigned long data) | |
205 | { | |
fd3f8c4c | 206 | struct sock *sk = (struct sock *)data; |
1da177e4 | 207 | struct tcp_sock *tp = tcp_sk(sk); |
463c84b9 | 208 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
209 | |
210 | bh_lock_sock(sk); | |
211 | if (sock_owned_by_user(sk)) { | |
212 | /* Try again later. */ | |
463c84b9 | 213 | icsk->icsk_ack.blocked = 1; |
de0744af | 214 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED); |
463c84b9 | 215 | sk_reset_timer(sk, &icsk->icsk_delack_timer, jiffies + TCP_DELACK_MIN); |
1da177e4 LT |
216 | goto out_unlock; |
217 | } | |
218 | ||
9993e7d3 | 219 | sk_mem_reclaim_partial(sk); |
1da177e4 | 220 | |
463c84b9 | 221 | if (sk->sk_state == TCP_CLOSE || !(icsk->icsk_ack.pending & ICSK_ACK_TIMER)) |
1da177e4 LT |
222 | goto out; |
223 | ||
463c84b9 ACM |
224 | if (time_after(icsk->icsk_ack.timeout, jiffies)) { |
225 | sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout); | |
1da177e4 LT |
226 | goto out; |
227 | } | |
463c84b9 | 228 | icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER; |
1da177e4 | 229 | |
b03efcfb | 230 | if (!skb_queue_empty(&tp->ucopy.prequeue)) { |
1da177e4 LT |
231 | struct sk_buff *skb; |
232 | ||
de0744af | 233 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSCHEDULERFAILED); |
1da177e4 LT |
234 | |
235 | while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) | |
c57943a1 | 236 | sk_backlog_rcv(sk, skb); |
1da177e4 LT |
237 | |
238 | tp->ucopy.memory = 0; | |
239 | } | |
240 | ||
463c84b9 ACM |
241 | if (inet_csk_ack_scheduled(sk)) { |
242 | if (!icsk->icsk_ack.pingpong) { | |
1da177e4 | 243 | /* Delayed ACK missed: inflate ATO. */ |
463c84b9 | 244 | icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1, icsk->icsk_rto); |
1da177e4 LT |
245 | } else { |
246 | /* Delayed ACK missed: leave pingpong mode and | |
247 | * deflate ATO. | |
248 | */ | |
463c84b9 ACM |
249 | icsk->icsk_ack.pingpong = 0; |
250 | icsk->icsk_ack.ato = TCP_ATO_MIN; | |
1da177e4 LT |
251 | } |
252 | tcp_send_ack(sk); | |
de0744af | 253 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKS); |
1da177e4 LT |
254 | } |
255 | TCP_CHECK_TIMER(sk); | |
256 | ||
257 | out: | |
258 | if (tcp_memory_pressure) | |
3ab224be | 259 | sk_mem_reclaim(sk); |
1da177e4 LT |
260 | out_unlock: |
261 | bh_unlock_sock(sk); | |
262 | sock_put(sk); | |
263 | } | |
264 | ||
265 | static void tcp_probe_timer(struct sock *sk) | |
266 | { | |
6687e988 | 267 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
268 | struct tcp_sock *tp = tcp_sk(sk); |
269 | int max_probes; | |
270 | ||
fe067e8a | 271 | if (tp->packets_out || !tcp_send_head(sk)) { |
6687e988 | 272 | icsk->icsk_probes_out = 0; |
1da177e4 LT |
273 | return; |
274 | } | |
275 | ||
276 | /* *WARNING* RFC 1122 forbids this | |
277 | * | |
278 | * It doesn't AFAIK, because we kill the retransmit timer -AK | |
279 | * | |
280 | * FIXME: We ought not to do it, Solaris 2.5 actually has fixing | |
281 | * this behaviour in Solaris down as a bug fix. [AC] | |
282 | * | |
6687e988 | 283 | * Let me to explain. icsk_probes_out is zeroed by incoming ACKs |
1da177e4 LT |
284 | * even if they advertise zero window. Hence, connection is killed only |
285 | * if we received no ACKs for normal connection timeout. It is not killed | |
286 | * only because window stays zero for some time, window may be zero | |
287 | * until armageddon and even later. We are in full accordance | |
288 | * with RFCs, only probe timer combines both retransmission timeout | |
289 | * and probe timeout in one bottle. --ANK | |
290 | */ | |
291 | max_probes = sysctl_tcp_retries2; | |
292 | ||
293 | if (sock_flag(sk, SOCK_DEAD)) { | |
463c84b9 | 294 | const int alive = ((icsk->icsk_rto << icsk->icsk_backoff) < TCP_RTO_MAX); |
e905a9ed | 295 | |
1da177e4 LT |
296 | max_probes = tcp_orphan_retries(sk, alive); |
297 | ||
6687e988 | 298 | if (tcp_out_of_resources(sk, alive || icsk->icsk_probes_out <= max_probes)) |
1da177e4 LT |
299 | return; |
300 | } | |
301 | ||
6687e988 | 302 | if (icsk->icsk_probes_out > max_probes) { |
1da177e4 LT |
303 | tcp_write_err(sk); |
304 | } else { | |
305 | /* Only send another probe if we didn't close things up. */ | |
306 | tcp_send_probe0(sk); | |
307 | } | |
308 | } | |
309 | ||
310 | /* | |
311 | * The TCP retransmit timer. | |
312 | */ | |
313 | ||
f1ecd5d9 | 314 | void tcp_retransmit_timer(struct sock *sk) |
1da177e4 LT |
315 | { |
316 | struct tcp_sock *tp = tcp_sk(sk); | |
463c84b9 | 317 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
318 | |
319 | if (!tp->packets_out) | |
320 | goto out; | |
321 | ||
547b792c | 322 | WARN_ON(tcp_write_queue_empty(sk)); |
1da177e4 LT |
323 | |
324 | if (!tp->snd_wnd && !sock_flag(sk, SOCK_DEAD) && | |
325 | !((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))) { | |
326 | /* Receiver dastardly shrinks window. Our retransmits | |
327 | * become zero probes, but we should not timeout this | |
328 | * connection. If the socket is an orphan, time it out, | |
329 | * we cannot allow such beasts to hang infinitely. | |
330 | */ | |
331 | #ifdef TCP_DEBUG | |
569508c9 YH |
332 | struct inet_sock *inet = inet_sk(sk); |
333 | if (sk->sk_family == AF_INET) { | |
6086ebca | 334 | LIMIT_NETDEBUG(KERN_DEBUG "TCP: Peer %pI4:%u/%u unexpectedly shrunk window %u:%u (repaired)\n", |
c720c7e8 ED |
335 | &inet->inet_daddr, ntohs(inet->inet_dport), |
336 | inet->inet_num, tp->snd_una, tp->snd_nxt); | |
1da177e4 | 337 | } |
569508c9 YH |
338 | #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) |
339 | else if (sk->sk_family == AF_INET6) { | |
340 | struct ipv6_pinfo *np = inet6_sk(sk); | |
6086ebca | 341 | LIMIT_NETDEBUG(KERN_DEBUG "TCP: Peer %pI6:%u/%u unexpectedly shrunk window %u:%u (repaired)\n", |
c720c7e8 ED |
342 | &np->daddr, ntohs(inet->inet_dport), |
343 | inet->inet_num, tp->snd_una, tp->snd_nxt); | |
569508c9 YH |
344 | } |
345 | #endif | |
1da177e4 LT |
346 | #endif |
347 | if (tcp_time_stamp - tp->rcv_tstamp > TCP_RTO_MAX) { | |
348 | tcp_write_err(sk); | |
349 | goto out; | |
350 | } | |
351 | tcp_enter_loss(sk, 0); | |
fe067e8a | 352 | tcp_retransmit_skb(sk, tcp_write_queue_head(sk)); |
1da177e4 LT |
353 | __sk_dst_reset(sk); |
354 | goto out_reset_timer; | |
355 | } | |
356 | ||
357 | if (tcp_write_timeout(sk)) | |
358 | goto out; | |
359 | ||
463c84b9 | 360 | if (icsk->icsk_retransmits == 0) { |
40b215e5 PE |
361 | int mib_idx; |
362 | ||
bc079e9e IJ |
363 | if (icsk->icsk_ca_state == TCP_CA_Disorder) { |
364 | if (tcp_is_sack(tp)) | |
365 | mib_idx = LINUX_MIB_TCPSACKFAILURES; | |
366 | else | |
367 | mib_idx = LINUX_MIB_TCPRENOFAILURES; | |
368 | } else if (icsk->icsk_ca_state == TCP_CA_Recovery) { | |
369 | if (tcp_is_sack(tp)) | |
370 | mib_idx = LINUX_MIB_TCPSACKRECOVERYFAIL; | |
371 | else | |
372 | mib_idx = LINUX_MIB_TCPRENORECOVERYFAIL; | |
6687e988 | 373 | } else if (icsk->icsk_ca_state == TCP_CA_Loss) { |
40b215e5 | 374 | mib_idx = LINUX_MIB_TCPLOSSFAILURES; |
1da177e4 | 375 | } else { |
40b215e5 | 376 | mib_idx = LINUX_MIB_TCPTIMEOUTS; |
1da177e4 | 377 | } |
de0744af | 378 | NET_INC_STATS_BH(sock_net(sk), mib_idx); |
1da177e4 LT |
379 | } |
380 | ||
381 | if (tcp_use_frto(sk)) { | |
382 | tcp_enter_frto(sk); | |
383 | } else { | |
384 | tcp_enter_loss(sk, 0); | |
385 | } | |
386 | ||
fe067e8a | 387 | if (tcp_retransmit_skb(sk, tcp_write_queue_head(sk)) > 0) { |
1da177e4 LT |
388 | /* Retransmission failed because of local congestion, |
389 | * do not backoff. | |
390 | */ | |
463c84b9 ACM |
391 | if (!icsk->icsk_retransmits) |
392 | icsk->icsk_retransmits = 1; | |
393 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, | |
3f421baa ACM |
394 | min(icsk->icsk_rto, TCP_RESOURCE_PROBE_INTERVAL), |
395 | TCP_RTO_MAX); | |
1da177e4 LT |
396 | goto out; |
397 | } | |
398 | ||
399 | /* Increase the timeout each time we retransmit. Note that | |
400 | * we do not increase the rtt estimate. rto is initialized | |
401 | * from rtt, but increases here. Jacobson (SIGCOMM 88) suggests | |
402 | * that doubling rto each time is the least we can get away with. | |
403 | * In KA9Q, Karn uses this for the first few times, and then | |
404 | * goes to quadratic. netBSD doubles, but only goes up to *64, | |
405 | * and clamps at 1 to 64 sec afterwards. Note that 120 sec is | |
406 | * defined in the protocol as the maximum possible RTT. I guess | |
407 | * we'll have to use something other than TCP to talk to the | |
408 | * University of Mars. | |
409 | * | |
410 | * PAWS allows us longer timeouts and large windows, so once | |
411 | * implemented ftp to mars will work nicely. We will have to fix | |
412 | * the 120 second clamps though! | |
413 | */ | |
463c84b9 ACM |
414 | icsk->icsk_backoff++; |
415 | icsk->icsk_retransmits++; | |
1da177e4 LT |
416 | |
417 | out_reset_timer: | |
463c84b9 | 418 | icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX); |
3f421baa | 419 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, TCP_RTO_MAX); |
6fa12c85 | 420 | if (retransmits_timed_out(sk, sysctl_tcp_retries1 + 1)) |
1da177e4 LT |
421 | __sk_dst_reset(sk); |
422 | ||
423 | out:; | |
424 | } | |
425 | ||
426 | static void tcp_write_timer(unsigned long data) | |
427 | { | |
fd3f8c4c | 428 | struct sock *sk = (struct sock *)data; |
463c84b9 | 429 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
430 | int event; |
431 | ||
432 | bh_lock_sock(sk); | |
433 | if (sock_owned_by_user(sk)) { | |
434 | /* Try again later */ | |
463c84b9 | 435 | sk_reset_timer(sk, &icsk->icsk_retransmit_timer, jiffies + (HZ / 20)); |
1da177e4 LT |
436 | goto out_unlock; |
437 | } | |
438 | ||
463c84b9 | 439 | if (sk->sk_state == TCP_CLOSE || !icsk->icsk_pending) |
1da177e4 LT |
440 | goto out; |
441 | ||
463c84b9 ACM |
442 | if (time_after(icsk->icsk_timeout, jiffies)) { |
443 | sk_reset_timer(sk, &icsk->icsk_retransmit_timer, icsk->icsk_timeout); | |
1da177e4 LT |
444 | goto out; |
445 | } | |
446 | ||
463c84b9 ACM |
447 | event = icsk->icsk_pending; |
448 | icsk->icsk_pending = 0; | |
1da177e4 LT |
449 | |
450 | switch (event) { | |
463c84b9 | 451 | case ICSK_TIME_RETRANS: |
1da177e4 LT |
452 | tcp_retransmit_timer(sk); |
453 | break; | |
463c84b9 | 454 | case ICSK_TIME_PROBE0: |
1da177e4 LT |
455 | tcp_probe_timer(sk); |
456 | break; | |
457 | } | |
458 | TCP_CHECK_TIMER(sk); | |
459 | ||
460 | out: | |
3ab224be | 461 | sk_mem_reclaim(sk); |
1da177e4 LT |
462 | out_unlock: |
463 | bh_unlock_sock(sk); | |
464 | sock_put(sk); | |
465 | } | |
466 | ||
295f7324 ACM |
467 | /* |
468 | * Timer for listening sockets | |
469 | */ | |
470 | ||
471 | static void tcp_synack_timer(struct sock *sk) | |
472 | { | |
a019d6fe ACM |
473 | inet_csk_reqsk_queue_prune(sk, TCP_SYNQ_INTERVAL, |
474 | TCP_TIMEOUT_INIT, TCP_RTO_MAX); | |
1da177e4 LT |
475 | } |
476 | ||
1da177e4 LT |
477 | void tcp_set_keepalive(struct sock *sk, int val) |
478 | { | |
479 | if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) | |
480 | return; | |
481 | ||
482 | if (val && !sock_flag(sk, SOCK_KEEPOPEN)) | |
463c84b9 | 483 | inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tcp_sk(sk))); |
1da177e4 | 484 | else if (!val) |
463c84b9 | 485 | inet_csk_delete_keepalive_timer(sk); |
1da177e4 LT |
486 | } |
487 | ||
488 | ||
489 | static void tcp_keepalive_timer (unsigned long data) | |
490 | { | |
491 | struct sock *sk = (struct sock *) data; | |
6687e988 | 492 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
493 | struct tcp_sock *tp = tcp_sk(sk); |
494 | __u32 elapsed; | |
495 | ||
496 | /* Only process if socket is not in use. */ | |
497 | bh_lock_sock(sk); | |
498 | if (sock_owned_by_user(sk)) { | |
e905a9ed | 499 | /* Try again later. */ |
463c84b9 | 500 | inet_csk_reset_keepalive_timer (sk, HZ/20); |
1da177e4 LT |
501 | goto out; |
502 | } | |
503 | ||
504 | if (sk->sk_state == TCP_LISTEN) { | |
505 | tcp_synack_timer(sk); | |
506 | goto out; | |
507 | } | |
508 | ||
509 | if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) { | |
510 | if (tp->linger2 >= 0) { | |
463c84b9 | 511 | const int tmo = tcp_fin_time(sk) - TCP_TIMEWAIT_LEN; |
1da177e4 LT |
512 | |
513 | if (tmo > 0) { | |
514 | tcp_time_wait(sk, TCP_FIN_WAIT2, tmo); | |
515 | goto out; | |
516 | } | |
517 | } | |
518 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
519 | goto death; | |
520 | } | |
521 | ||
522 | if (!sock_flag(sk, SOCK_KEEPOPEN) || sk->sk_state == TCP_CLOSE) | |
523 | goto out; | |
524 | ||
525 | elapsed = keepalive_time_when(tp); | |
526 | ||
527 | /* It is alive without keepalive 8) */ | |
fe067e8a | 528 | if (tp->packets_out || tcp_send_head(sk)) |
1da177e4 LT |
529 | goto resched; |
530 | ||
531 | elapsed = tcp_time_stamp - tp->rcv_tstamp; | |
532 | ||
533 | if (elapsed >= keepalive_time_when(tp)) { | |
df19a626 | 534 | if (icsk->icsk_probes_out >= keepalive_probes(tp)) { |
1da177e4 LT |
535 | tcp_send_active_reset(sk, GFP_ATOMIC); |
536 | tcp_write_err(sk); | |
537 | goto out; | |
538 | } | |
539 | if (tcp_write_wakeup(sk) <= 0) { | |
6687e988 | 540 | icsk->icsk_probes_out++; |
1da177e4 LT |
541 | elapsed = keepalive_intvl_when(tp); |
542 | } else { | |
543 | /* If keepalive was lost due to local congestion, | |
544 | * try harder. | |
545 | */ | |
546 | elapsed = TCP_RESOURCE_PROBE_INTERVAL; | |
547 | } | |
548 | } else { | |
549 | /* It is tp->rcv_tstamp + keepalive_time_when(tp) */ | |
550 | elapsed = keepalive_time_when(tp) - elapsed; | |
551 | } | |
552 | ||
553 | TCP_CHECK_TIMER(sk); | |
3ab224be | 554 | sk_mem_reclaim(sk); |
1da177e4 LT |
555 | |
556 | resched: | |
463c84b9 | 557 | inet_csk_reset_keepalive_timer (sk, elapsed); |
1da177e4 LT |
558 | goto out; |
559 | ||
e905a9ed | 560 | death: |
1da177e4 LT |
561 | tcp_done(sk); |
562 | ||
563 | out: | |
564 | bh_unlock_sock(sk); | |
565 | sock_put(sk); | |
566 | } |