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 | * | |
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> | |
5a0e3ad6 | 22 | #include <linux/gfp.h> |
1da177e4 LT |
23 | #include <net/tcp.h> |
24 | ||
ab32ea5d BH |
25 | int sysctl_tcp_syn_retries __read_mostly = TCP_SYN_RETRIES; |
26 | int sysctl_tcp_synack_retries __read_mostly = TCP_SYNACK_RETRIES; | |
27 | int sysctl_tcp_keepalive_time __read_mostly = TCP_KEEPALIVE_TIME; | |
28 | int sysctl_tcp_keepalive_probes __read_mostly = TCP_KEEPALIVE_PROBES; | |
29 | int sysctl_tcp_keepalive_intvl __read_mostly = TCP_KEEPALIVE_INTVL; | |
30 | int sysctl_tcp_retries1 __read_mostly = TCP_RETR1; | |
31 | int sysctl_tcp_retries2 __read_mostly = TCP_RETR2; | |
32 | int sysctl_tcp_orphan_retries __read_mostly; | |
36e31b0a | 33 | int sysctl_tcp_thin_linear_timeouts __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 | } | |
3f421baa ACM |
44 | EXPORT_SYMBOL(tcp_init_xmit_timers); |
45 | ||
1da177e4 LT |
46 | static void tcp_write_err(struct sock *sk) |
47 | { | |
48 | sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT; | |
49 | sk->sk_error_report(sk); | |
50 | ||
51 | tcp_done(sk); | |
de0744af | 52 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONTIMEOUT); |
1da177e4 LT |
53 | } |
54 | ||
55 | /* Do not allow orphaned sockets to eat all our resources. | |
56 | * This is direct violation of TCP specs, but it is required | |
57 | * to prevent DoS attacks. It is called when a retransmission timeout | |
58 | * or zero probe timeout occurs on orphaned socket. | |
59 | * | |
caa20d9a | 60 | * Criteria is still not confirmed experimentally and may change. |
1da177e4 LT |
61 | * We kill the socket, if: |
62 | * 1. If number of orphaned sockets exceeds an administratively configured | |
63 | * limit. | |
64 | * 2. If we have strong memory pressure. | |
65 | */ | |
66 | static int tcp_out_of_resources(struct sock *sk, int do_reset) | |
67 | { | |
68 | struct tcp_sock *tp = tcp_sk(sk); | |
ad1af0fe | 69 | int shift = 0; |
1da177e4 | 70 | |
e905a9ed | 71 | /* If peer does not open window for long time, or did not transmit |
1da177e4 LT |
72 | * anything for long time, penalize it. */ |
73 | if ((s32)(tcp_time_stamp - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset) | |
ad1af0fe | 74 | shift++; |
1da177e4 LT |
75 | |
76 | /* If some dubious ICMP arrived, penalize even more. */ | |
77 | if (sk->sk_err_soft) | |
ad1af0fe | 78 | shift++; |
1da177e4 | 79 | |
ad1af0fe | 80 | if (tcp_too_many_orphans(sk, shift)) { |
1da177e4 LT |
81 | if (net_ratelimit()) |
82 | printk(KERN_INFO "Out of socket memory\n"); | |
83 | ||
84 | /* Catch exceptional cases, when connection requires reset. | |
85 | * 1. Last segment was sent recently. */ | |
86 | if ((s32)(tcp_time_stamp - tp->lsndtime) <= TCP_TIMEWAIT_LEN || | |
87 | /* 2. Window is closed. */ | |
88 | (!tp->snd_wnd && !tp->packets_out)) | |
89 | do_reset = 1; | |
90 | if (do_reset) | |
91 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
92 | tcp_done(sk); | |
de0744af | 93 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY); |
1da177e4 LT |
94 | return 1; |
95 | } | |
96 | return 0; | |
97 | } | |
98 | ||
99 | /* Calculate maximal number or retries on an orphaned socket. */ | |
100 | static int tcp_orphan_retries(struct sock *sk, int alive) | |
101 | { | |
102 | int retries = sysctl_tcp_orphan_retries; /* May be zero. */ | |
103 | ||
104 | /* We know from an ICMP that something is wrong. */ | |
105 | if (sk->sk_err_soft && !alive) | |
106 | retries = 0; | |
107 | ||
108 | /* However, if socket sent something recently, select some safe | |
109 | * number of retries. 8 corresponds to >100 seconds with minimal | |
110 | * RTO of 200msec. */ | |
111 | if (retries == 0 && alive) | |
112 | retries = 8; | |
113 | return retries; | |
114 | } | |
115 | ||
ce55dd36 ED |
116 | static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk) |
117 | { | |
ce55dd36 ED |
118 | /* Black hole detection */ |
119 | if (sysctl_tcp_mtu_probing) { | |
120 | if (!icsk->icsk_mtup.enabled) { | |
121 | icsk->icsk_mtup.enabled = 1; | |
122 | tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); | |
123 | } else { | |
124 | struct tcp_sock *tp = tcp_sk(sk); | |
829942c1 DM |
125 | int mss; |
126 | ||
8beb5c5f | 127 | mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1; |
ce55dd36 ED |
128 | mss = min(sysctl_tcp_base_mss, mss); |
129 | mss = max(mss, 68 - tp->tcp_header_len); | |
130 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); | |
131 | tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); | |
132 | } | |
133 | } | |
134 | } | |
135 | ||
2f7de571 | 136 | /* This function calculates a "timeout" which is equivalent to the timeout of a |
3ad2f3fb | 137 | * TCP connection after "boundary" unsuccessful, exponentially backed-off |
4d22f7d3 DL |
138 | * retransmissions with an initial RTO of TCP_RTO_MIN or TCP_TIMEOUT_INIT if |
139 | * syn_set flag is set. | |
2f7de571 DL |
140 | */ |
141 | static bool retransmits_timed_out(struct sock *sk, | |
dca43c75 | 142 | unsigned int boundary, |
21a180cd | 143 | unsigned int timeout, |
4d22f7d3 | 144 | bool syn_set) |
2f7de571 | 145 | { |
dca43c75 | 146 | unsigned int linear_backoff_thresh, start_ts; |
4d22f7d3 | 147 | unsigned int rto_base = syn_set ? TCP_TIMEOUT_INIT : TCP_RTO_MIN; |
2f7de571 DL |
148 | |
149 | if (!inet_csk(sk)->icsk_retransmits) | |
150 | return false; | |
151 | ||
152 | if (unlikely(!tcp_sk(sk)->retrans_stamp)) | |
153 | start_ts = TCP_SKB_CB(tcp_write_queue_head(sk))->when; | |
154 | else | |
155 | start_ts = tcp_sk(sk)->retrans_stamp; | |
156 | ||
dca43c75 | 157 | if (likely(timeout == 0)) { |
21a180cd | 158 | linear_backoff_thresh = ilog2(TCP_RTO_MAX/rto_base); |
2f7de571 | 159 | |
dca43c75 | 160 | if (boundary <= linear_backoff_thresh) |
21a180cd | 161 | timeout = ((2 << boundary) - 1) * rto_base; |
dca43c75 | 162 | else |
21a180cd | 163 | timeout = ((2 << linear_backoff_thresh) - 1) * rto_base + |
dca43c75 JC |
164 | (boundary - linear_backoff_thresh) * TCP_RTO_MAX; |
165 | } | |
2f7de571 DL |
166 | return (tcp_time_stamp - start_ts) >= timeout; |
167 | } | |
168 | ||
1da177e4 LT |
169 | /* A write timeout has occurred. Process the after effects. */ |
170 | static int tcp_write_timeout(struct sock *sk) | |
171 | { | |
5d424d5a | 172 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 173 | int retry_until; |
4d22f7d3 | 174 | bool do_reset, syn_set = 0; |
1da177e4 LT |
175 | |
176 | if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { | |
463c84b9 | 177 | if (icsk->icsk_retransmits) |
b6c6712a | 178 | dst_negative_advice(sk); |
463c84b9 | 179 | retry_until = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries; |
4d22f7d3 | 180 | syn_set = 1; |
1da177e4 | 181 | } else { |
21a180cd | 182 | if (retransmits_timed_out(sk, sysctl_tcp_retries1, 0, 0)) { |
5d424d5a | 183 | /* Black hole detection */ |
ce55dd36 | 184 | tcp_mtu_probing(icsk, sk); |
1da177e4 | 185 | |
b6c6712a | 186 | dst_negative_advice(sk); |
1da177e4 LT |
187 | } |
188 | ||
189 | retry_until = sysctl_tcp_retries2; | |
190 | if (sock_flag(sk, SOCK_DEAD)) { | |
463c84b9 | 191 | const int alive = (icsk->icsk_rto < TCP_RTO_MAX); |
e905a9ed | 192 | |
1da177e4 | 193 | retry_until = tcp_orphan_retries(sk, alive); |
6fa12c85 | 194 | do_reset = alive || |
21a180cd | 195 | !retransmits_timed_out(sk, retry_until, 0, 0); |
1da177e4 | 196 | |
6fa12c85 | 197 | if (tcp_out_of_resources(sk, do_reset)) |
1da177e4 LT |
198 | return 1; |
199 | } | |
200 | } | |
201 | ||
dca43c75 | 202 | if (retransmits_timed_out(sk, retry_until, |
21a180cd | 203 | syn_set ? 0 : icsk->icsk_user_timeout, syn_set)) { |
1da177e4 LT |
204 | /* Has it gone just too far? */ |
205 | tcp_write_err(sk); | |
206 | return 1; | |
207 | } | |
208 | return 0; | |
209 | } | |
210 | ||
211 | static void tcp_delack_timer(unsigned long data) | |
212 | { | |
fd3f8c4c | 213 | struct sock *sk = (struct sock *)data; |
1da177e4 | 214 | struct tcp_sock *tp = tcp_sk(sk); |
463c84b9 | 215 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
216 | |
217 | bh_lock_sock(sk); | |
218 | if (sock_owned_by_user(sk)) { | |
219 | /* Try again later. */ | |
463c84b9 | 220 | icsk->icsk_ack.blocked = 1; |
de0744af | 221 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED); |
463c84b9 | 222 | sk_reset_timer(sk, &icsk->icsk_delack_timer, jiffies + TCP_DELACK_MIN); |
1da177e4 LT |
223 | goto out_unlock; |
224 | } | |
225 | ||
9993e7d3 | 226 | sk_mem_reclaim_partial(sk); |
1da177e4 | 227 | |
463c84b9 | 228 | if (sk->sk_state == TCP_CLOSE || !(icsk->icsk_ack.pending & ICSK_ACK_TIMER)) |
1da177e4 LT |
229 | goto out; |
230 | ||
463c84b9 ACM |
231 | if (time_after(icsk->icsk_ack.timeout, jiffies)) { |
232 | sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout); | |
1da177e4 LT |
233 | goto out; |
234 | } | |
463c84b9 | 235 | icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER; |
1da177e4 | 236 | |
b03efcfb | 237 | if (!skb_queue_empty(&tp->ucopy.prequeue)) { |
1da177e4 LT |
238 | struct sk_buff *skb; |
239 | ||
de0744af | 240 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSCHEDULERFAILED); |
1da177e4 LT |
241 | |
242 | while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) | |
c57943a1 | 243 | sk_backlog_rcv(sk, skb); |
1da177e4 LT |
244 | |
245 | tp->ucopy.memory = 0; | |
246 | } | |
247 | ||
463c84b9 ACM |
248 | if (inet_csk_ack_scheduled(sk)) { |
249 | if (!icsk->icsk_ack.pingpong) { | |
1da177e4 | 250 | /* Delayed ACK missed: inflate ATO. */ |
463c84b9 | 251 | icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1, icsk->icsk_rto); |
1da177e4 LT |
252 | } else { |
253 | /* Delayed ACK missed: leave pingpong mode and | |
254 | * deflate ATO. | |
255 | */ | |
463c84b9 ACM |
256 | icsk->icsk_ack.pingpong = 0; |
257 | icsk->icsk_ack.ato = TCP_ATO_MIN; | |
1da177e4 LT |
258 | } |
259 | tcp_send_ack(sk); | |
de0744af | 260 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKS); |
1da177e4 | 261 | } |
1da177e4 LT |
262 | |
263 | out: | |
264 | if (tcp_memory_pressure) | |
3ab224be | 265 | sk_mem_reclaim(sk); |
1da177e4 LT |
266 | out_unlock: |
267 | bh_unlock_sock(sk); | |
268 | sock_put(sk); | |
269 | } | |
270 | ||
271 | static void tcp_probe_timer(struct sock *sk) | |
272 | { | |
6687e988 | 273 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
274 | struct tcp_sock *tp = tcp_sk(sk); |
275 | int max_probes; | |
276 | ||
fe067e8a | 277 | if (tp->packets_out || !tcp_send_head(sk)) { |
6687e988 | 278 | icsk->icsk_probes_out = 0; |
1da177e4 LT |
279 | return; |
280 | } | |
281 | ||
282 | /* *WARNING* RFC 1122 forbids this | |
283 | * | |
284 | * It doesn't AFAIK, because we kill the retransmit timer -AK | |
285 | * | |
286 | * FIXME: We ought not to do it, Solaris 2.5 actually has fixing | |
287 | * this behaviour in Solaris down as a bug fix. [AC] | |
288 | * | |
6687e988 | 289 | * Let me to explain. icsk_probes_out is zeroed by incoming ACKs |
1da177e4 LT |
290 | * even if they advertise zero window. Hence, connection is killed only |
291 | * if we received no ACKs for normal connection timeout. It is not killed | |
292 | * only because window stays zero for some time, window may be zero | |
293 | * until armageddon and even later. We are in full accordance | |
294 | * with RFCs, only probe timer combines both retransmission timeout | |
295 | * and probe timeout in one bottle. --ANK | |
296 | */ | |
297 | max_probes = sysctl_tcp_retries2; | |
298 | ||
299 | if (sock_flag(sk, SOCK_DEAD)) { | |
463c84b9 | 300 | const int alive = ((icsk->icsk_rto << icsk->icsk_backoff) < TCP_RTO_MAX); |
e905a9ed | 301 | |
1da177e4 LT |
302 | max_probes = tcp_orphan_retries(sk, alive); |
303 | ||
6687e988 | 304 | if (tcp_out_of_resources(sk, alive || icsk->icsk_probes_out <= max_probes)) |
1da177e4 LT |
305 | return; |
306 | } | |
307 | ||
6687e988 | 308 | if (icsk->icsk_probes_out > max_probes) { |
1da177e4 LT |
309 | tcp_write_err(sk); |
310 | } else { | |
311 | /* Only send another probe if we didn't close things up. */ | |
312 | tcp_send_probe0(sk); | |
313 | } | |
314 | } | |
315 | ||
316 | /* | |
317 | * The TCP retransmit timer. | |
318 | */ | |
319 | ||
f1ecd5d9 | 320 | void tcp_retransmit_timer(struct sock *sk) |
1da177e4 LT |
321 | { |
322 | struct tcp_sock *tp = tcp_sk(sk); | |
463c84b9 | 323 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
324 | |
325 | if (!tp->packets_out) | |
326 | goto out; | |
327 | ||
547b792c | 328 | WARN_ON(tcp_write_queue_empty(sk)); |
1da177e4 LT |
329 | |
330 | if (!tp->snd_wnd && !sock_flag(sk, SOCK_DEAD) && | |
331 | !((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))) { | |
332 | /* Receiver dastardly shrinks window. Our retransmits | |
333 | * become zero probes, but we should not timeout this | |
334 | * connection. If the socket is an orphan, time it out, | |
335 | * we cannot allow such beasts to hang infinitely. | |
336 | */ | |
569508c9 YH |
337 | struct inet_sock *inet = inet_sk(sk); |
338 | if (sk->sk_family == AF_INET) { | |
6086ebca | 339 | LIMIT_NETDEBUG(KERN_DEBUG "TCP: Peer %pI4:%u/%u unexpectedly shrunk window %u:%u (repaired)\n", |
c720c7e8 ED |
340 | &inet->inet_daddr, ntohs(inet->inet_dport), |
341 | inet->inet_num, tp->snd_una, tp->snd_nxt); | |
1da177e4 | 342 | } |
569508c9 YH |
343 | #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) |
344 | else if (sk->sk_family == AF_INET6) { | |
345 | struct ipv6_pinfo *np = inet6_sk(sk); | |
6086ebca | 346 | LIMIT_NETDEBUG(KERN_DEBUG "TCP: Peer %pI6:%u/%u unexpectedly shrunk window %u:%u (repaired)\n", |
c720c7e8 ED |
347 | &np->daddr, ntohs(inet->inet_dport), |
348 | inet->inet_num, tp->snd_una, tp->snd_nxt); | |
569508c9 | 349 | } |
1da177e4 LT |
350 | #endif |
351 | if (tcp_time_stamp - tp->rcv_tstamp > TCP_RTO_MAX) { | |
352 | tcp_write_err(sk); | |
353 | goto out; | |
354 | } | |
355 | tcp_enter_loss(sk, 0); | |
fe067e8a | 356 | tcp_retransmit_skb(sk, tcp_write_queue_head(sk)); |
1da177e4 LT |
357 | __sk_dst_reset(sk); |
358 | goto out_reset_timer; | |
359 | } | |
360 | ||
361 | if (tcp_write_timeout(sk)) | |
362 | goto out; | |
363 | ||
463c84b9 | 364 | if (icsk->icsk_retransmits == 0) { |
40b215e5 PE |
365 | int mib_idx; |
366 | ||
c60ce4e2 | 367 | if (icsk->icsk_ca_state == TCP_CA_Recovery) { |
bc079e9e IJ |
368 | if (tcp_is_sack(tp)) |
369 | mib_idx = LINUX_MIB_TCPSACKRECOVERYFAIL; | |
370 | else | |
371 | mib_idx = LINUX_MIB_TCPRENORECOVERYFAIL; | |
6687e988 | 372 | } else if (icsk->icsk_ca_state == TCP_CA_Loss) { |
40b215e5 | 373 | mib_idx = LINUX_MIB_TCPLOSSFAILURES; |
c60ce4e2 IJ |
374 | } else if ((icsk->icsk_ca_state == TCP_CA_Disorder) || |
375 | tp->sacked_out) { | |
376 | if (tcp_is_sack(tp)) | |
377 | mib_idx = LINUX_MIB_TCPSACKFAILURES; | |
378 | else | |
379 | mib_idx = LINUX_MIB_TCPRENOFAILURES; | |
1da177e4 | 380 | } else { |
40b215e5 | 381 | mib_idx = LINUX_MIB_TCPTIMEOUTS; |
1da177e4 | 382 | } |
de0744af | 383 | NET_INC_STATS_BH(sock_net(sk), mib_idx); |
1da177e4 LT |
384 | } |
385 | ||
386 | if (tcp_use_frto(sk)) { | |
387 | tcp_enter_frto(sk); | |
388 | } else { | |
389 | tcp_enter_loss(sk, 0); | |
390 | } | |
391 | ||
fe067e8a | 392 | if (tcp_retransmit_skb(sk, tcp_write_queue_head(sk)) > 0) { |
1da177e4 LT |
393 | /* Retransmission failed because of local congestion, |
394 | * do not backoff. | |
395 | */ | |
463c84b9 ACM |
396 | if (!icsk->icsk_retransmits) |
397 | icsk->icsk_retransmits = 1; | |
398 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, | |
3f421baa ACM |
399 | min(icsk->icsk_rto, TCP_RESOURCE_PROBE_INTERVAL), |
400 | TCP_RTO_MAX); | |
1da177e4 LT |
401 | goto out; |
402 | } | |
403 | ||
404 | /* Increase the timeout each time we retransmit. Note that | |
405 | * we do not increase the rtt estimate. rto is initialized | |
406 | * from rtt, but increases here. Jacobson (SIGCOMM 88) suggests | |
407 | * that doubling rto each time is the least we can get away with. | |
408 | * In KA9Q, Karn uses this for the first few times, and then | |
409 | * goes to quadratic. netBSD doubles, but only goes up to *64, | |
410 | * and clamps at 1 to 64 sec afterwards. Note that 120 sec is | |
411 | * defined in the protocol as the maximum possible RTT. I guess | |
412 | * we'll have to use something other than TCP to talk to the | |
413 | * University of Mars. | |
414 | * | |
415 | * PAWS allows us longer timeouts and large windows, so once | |
416 | * implemented ftp to mars will work nicely. We will have to fix | |
417 | * the 120 second clamps though! | |
418 | */ | |
463c84b9 ACM |
419 | icsk->icsk_backoff++; |
420 | icsk->icsk_retransmits++; | |
1da177e4 LT |
421 | |
422 | out_reset_timer: | |
36e31b0a AP |
423 | /* If stream is thin, use linear timeouts. Since 'icsk_backoff' is |
424 | * used to reset timer, set to 0. Recalculate 'icsk_rto' as this | |
425 | * might be increased if the stream oscillates between thin and thick, | |
426 | * thus the old value might already be too high compared to the value | |
427 | * set by 'tcp_set_rto' in tcp_input.c which resets the rto without | |
428 | * backoff. Limit to TCP_THIN_LINEAR_RETRIES before initiating | |
429 | * exponential backoff behaviour to avoid continue hammering | |
430 | * linear-timeout retransmissions into a black hole | |
431 | */ | |
432 | if (sk->sk_state == TCP_ESTABLISHED && | |
433 | (tp->thin_lto || sysctl_tcp_thin_linear_timeouts) && | |
434 | tcp_stream_is_thin(tp) && | |
435 | icsk->icsk_retransmits <= TCP_THIN_LINEAR_RETRIES) { | |
436 | icsk->icsk_backoff = 0; | |
437 | icsk->icsk_rto = min(__tcp_set_rto(tp), TCP_RTO_MAX); | |
438 | } else { | |
439 | /* Use normal (exponential) backoff */ | |
440 | icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX); | |
441 | } | |
3f421baa | 442 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, TCP_RTO_MAX); |
21a180cd | 443 | if (retransmits_timed_out(sk, sysctl_tcp_retries1 + 1, 0, 0)) |
1da177e4 LT |
444 | __sk_dst_reset(sk); |
445 | ||
446 | out:; | |
447 | } | |
448 | ||
449 | static void tcp_write_timer(unsigned long data) | |
450 | { | |
fd3f8c4c | 451 | struct sock *sk = (struct sock *)data; |
463c84b9 | 452 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
453 | int event; |
454 | ||
455 | bh_lock_sock(sk); | |
456 | if (sock_owned_by_user(sk)) { | |
457 | /* Try again later */ | |
463c84b9 | 458 | sk_reset_timer(sk, &icsk->icsk_retransmit_timer, jiffies + (HZ / 20)); |
1da177e4 LT |
459 | goto out_unlock; |
460 | } | |
461 | ||
463c84b9 | 462 | if (sk->sk_state == TCP_CLOSE || !icsk->icsk_pending) |
1da177e4 LT |
463 | goto out; |
464 | ||
463c84b9 ACM |
465 | if (time_after(icsk->icsk_timeout, jiffies)) { |
466 | sk_reset_timer(sk, &icsk->icsk_retransmit_timer, icsk->icsk_timeout); | |
1da177e4 LT |
467 | goto out; |
468 | } | |
469 | ||
463c84b9 ACM |
470 | event = icsk->icsk_pending; |
471 | icsk->icsk_pending = 0; | |
1da177e4 LT |
472 | |
473 | switch (event) { | |
463c84b9 | 474 | case ICSK_TIME_RETRANS: |
1da177e4 LT |
475 | tcp_retransmit_timer(sk); |
476 | break; | |
463c84b9 | 477 | case ICSK_TIME_PROBE0: |
1da177e4 LT |
478 | tcp_probe_timer(sk); |
479 | break; | |
480 | } | |
1da177e4 LT |
481 | |
482 | out: | |
3ab224be | 483 | sk_mem_reclaim(sk); |
1da177e4 LT |
484 | out_unlock: |
485 | bh_unlock_sock(sk); | |
486 | sock_put(sk); | |
487 | } | |
488 | ||
295f7324 ACM |
489 | /* |
490 | * Timer for listening sockets | |
491 | */ | |
492 | ||
493 | static void tcp_synack_timer(struct sock *sk) | |
494 | { | |
a019d6fe ACM |
495 | inet_csk_reqsk_queue_prune(sk, TCP_SYNQ_INTERVAL, |
496 | TCP_TIMEOUT_INIT, TCP_RTO_MAX); | |
1da177e4 LT |
497 | } |
498 | ||
72659ecc OP |
499 | void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req) |
500 | { | |
501 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPTIMEOUTS); | |
502 | } | |
503 | EXPORT_SYMBOL(tcp_syn_ack_timeout); | |
504 | ||
1da177e4 LT |
505 | void tcp_set_keepalive(struct sock *sk, int val) |
506 | { | |
507 | if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) | |
508 | return; | |
509 | ||
510 | if (val && !sock_flag(sk, SOCK_KEEPOPEN)) | |
463c84b9 | 511 | inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tcp_sk(sk))); |
1da177e4 | 512 | else if (!val) |
463c84b9 | 513 | inet_csk_delete_keepalive_timer(sk); |
1da177e4 LT |
514 | } |
515 | ||
516 | ||
517 | static void tcp_keepalive_timer (unsigned long data) | |
518 | { | |
519 | struct sock *sk = (struct sock *) data; | |
6687e988 | 520 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 521 | struct tcp_sock *tp = tcp_sk(sk); |
6c37e5de | 522 | u32 elapsed; |
1da177e4 LT |
523 | |
524 | /* Only process if socket is not in use. */ | |
525 | bh_lock_sock(sk); | |
526 | if (sock_owned_by_user(sk)) { | |
e905a9ed | 527 | /* Try again later. */ |
463c84b9 | 528 | inet_csk_reset_keepalive_timer (sk, HZ/20); |
1da177e4 LT |
529 | goto out; |
530 | } | |
531 | ||
532 | if (sk->sk_state == TCP_LISTEN) { | |
533 | tcp_synack_timer(sk); | |
534 | goto out; | |
535 | } | |
536 | ||
537 | if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) { | |
538 | if (tp->linger2 >= 0) { | |
463c84b9 | 539 | const int tmo = tcp_fin_time(sk) - TCP_TIMEWAIT_LEN; |
1da177e4 LT |
540 | |
541 | if (tmo > 0) { | |
542 | tcp_time_wait(sk, TCP_FIN_WAIT2, tmo); | |
543 | goto out; | |
544 | } | |
545 | } | |
546 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
547 | goto death; | |
548 | } | |
549 | ||
550 | if (!sock_flag(sk, SOCK_KEEPOPEN) || sk->sk_state == TCP_CLOSE) | |
551 | goto out; | |
552 | ||
553 | elapsed = keepalive_time_when(tp); | |
554 | ||
555 | /* It is alive without keepalive 8) */ | |
fe067e8a | 556 | if (tp->packets_out || tcp_send_head(sk)) |
1da177e4 LT |
557 | goto resched; |
558 | ||
6c37e5de | 559 | elapsed = keepalive_time_elapsed(tp); |
1da177e4 LT |
560 | |
561 | if (elapsed >= keepalive_time_when(tp)) { | |
dca43c75 JC |
562 | /* If the TCP_USER_TIMEOUT option is enabled, use that |
563 | * to determine when to timeout instead. | |
564 | */ | |
565 | if ((icsk->icsk_user_timeout != 0 && | |
566 | elapsed >= icsk->icsk_user_timeout && | |
567 | icsk->icsk_probes_out > 0) || | |
568 | (icsk->icsk_user_timeout == 0 && | |
569 | icsk->icsk_probes_out >= keepalive_probes(tp))) { | |
1da177e4 LT |
570 | tcp_send_active_reset(sk, GFP_ATOMIC); |
571 | tcp_write_err(sk); | |
572 | goto out; | |
573 | } | |
574 | if (tcp_write_wakeup(sk) <= 0) { | |
6687e988 | 575 | icsk->icsk_probes_out++; |
1da177e4 LT |
576 | elapsed = keepalive_intvl_when(tp); |
577 | } else { | |
578 | /* If keepalive was lost due to local congestion, | |
579 | * try harder. | |
580 | */ | |
581 | elapsed = TCP_RESOURCE_PROBE_INTERVAL; | |
582 | } | |
583 | } else { | |
584 | /* It is tp->rcv_tstamp + keepalive_time_when(tp) */ | |
585 | elapsed = keepalive_time_when(tp) - elapsed; | |
586 | } | |
587 | ||
3ab224be | 588 | sk_mem_reclaim(sk); |
1da177e4 LT |
589 | |
590 | resched: | |
463c84b9 | 591 | inet_csk_reset_keepalive_timer (sk, elapsed); |
1da177e4 LT |
592 | goto out; |
593 | ||
e905a9ed | 594 | death: |
1da177e4 LT |
595 | tcp_done(sk); |
596 | ||
597 | out: | |
598 | bh_unlock_sock(sk); | |
599 | sock_put(sk); | |
600 | } |