net: ethernet: ti: cpdma: correct error handling for chan create
[linux-block.git] / net / ipv4 / tcp_timer.c
CommitLineData
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
c380d37e
RS
25/**
26 * tcp_write_err() - close socket and save error info
27 * @sk: The socket the error has appeared on.
28 *
29 * Returns: Nothing (void)
30 */
31
1da177e4
LT
32static void tcp_write_err(struct sock *sk)
33{
34 sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT;
35 sk->sk_error_report(sk);
36
37 tcp_done(sk);
02a1d6e7 38 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONTIMEOUT);
1da177e4
LT
39}
40
c380d37e
RS
41/**
42 * tcp_out_of_resources() - Close socket if out of resources
43 * @sk: pointer to current socket
44 * @do_reset: send a last packet with reset flag
1da177e4 45 *
c380d37e
RS
46 * Do not allow orphaned sockets to eat all our resources.
47 * This is direct violation of TCP specs, but it is required
48 * to prevent DoS attacks. It is called when a retransmission timeout
49 * or zero probe timeout occurs on orphaned socket.
50 *
51 * Criteria is still not confirmed experimentally and may change.
52 * We kill the socket, if:
53 * 1. If number of orphaned sockets exceeds an administratively configured
54 * limit.
55 * 2. If we have strong memory pressure.
1da177e4 56 */
b248230c 57static int tcp_out_of_resources(struct sock *sk, bool do_reset)
1da177e4
LT
58{
59 struct tcp_sock *tp = tcp_sk(sk);
ad1af0fe 60 int shift = 0;
1da177e4 61
e905a9ed 62 /* If peer does not open window for long time, or did not transmit
1da177e4 63 * anything for long time, penalize it. */
d635fbe2 64 if ((s32)(tcp_jiffies32 - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset)
ad1af0fe 65 shift++;
1da177e4
LT
66
67 /* If some dubious ICMP arrived, penalize even more. */
68 if (sk->sk_err_soft)
ad1af0fe 69 shift++;
1da177e4 70
efcdbf24 71 if (tcp_check_oom(sk, shift)) {
1da177e4
LT
72 /* Catch exceptional cases, when connection requires reset.
73 * 1. Last segment was sent recently. */
d635fbe2 74 if ((s32)(tcp_jiffies32 - tp->lsndtime) <= TCP_TIMEWAIT_LEN ||
1da177e4
LT
75 /* 2. Window is closed. */
76 (!tp->snd_wnd && !tp->packets_out))
b248230c 77 do_reset = true;
1da177e4
LT
78 if (do_reset)
79 tcp_send_active_reset(sk, GFP_ATOMIC);
80 tcp_done(sk);
02a1d6e7 81 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY);
1da177e4
LT
82 return 1;
83 }
84 return 0;
85}
86
c380d37e
RS
87/**
88 * tcp_orphan_retries() - Returns maximal number of retries on an orphaned socket
89 * @sk: Pointer to the current socket.
90 * @alive: bool, socket alive state
91 */
7533ce30 92static int tcp_orphan_retries(struct sock *sk, bool alive)
1da177e4 93{
c402d9be 94 int retries = sock_net(sk)->ipv4.sysctl_tcp_orphan_retries; /* May be zero. */
1da177e4
LT
95
96 /* We know from an ICMP that something is wrong. */
97 if (sk->sk_err_soft && !alive)
98 retries = 0;
99
100 /* However, if socket sent something recently, select some safe
101 * number of retries. 8 corresponds to >100 seconds with minimal
102 * RTO of 200msec. */
103 if (retries == 0 && alive)
104 retries = 8;
105 return retries;
106}
107
ce55dd36
ED
108static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk)
109{
d0f36847
ED
110 const struct net *net = sock_net(sk);
111 int mss;
b0f9ca53 112
ce55dd36 113 /* Black hole detection */
d0f36847
ED
114 if (!net->ipv4.sysctl_tcp_mtu_probing)
115 return;
116
117 if (!icsk->icsk_mtup.enabled) {
118 icsk->icsk_mtup.enabled = 1;
119 icsk->icsk_mtup.probe_timestamp = tcp_jiffies32;
120 } else {
121 mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1;
122 mss = min(net->ipv4.sysctl_tcp_base_mss, mss);
123 mss = max(mss, 68 - tcp_sk(sk)->tcp_header_len);
124 icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss);
ce55dd36 125 }
d0f36847 126 tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
ce55dd36
ED
127}
128
c380d37e
RS
129
130/**
131 * retransmits_timed_out() - returns true if this connection has timed out
132 * @sk: The current socket
133 * @boundary: max number of retransmissions
134 * @timeout: A custom timeout value.
135 * If set to 0 the default timeout is calculated and used.
136 * Using TCP_RTO_MIN and the number of unsuccessful retransmits.
c380d37e
RS
137 *
138 * The default "timeout" value this function can calculate and use
139 * is equivalent to the timeout of a TCP Connection
140 * after "boundary" unsuccessful, exponentially backed-off
ce682ef6 141 * retransmissions with an initial RTO of TCP_RTO_MIN.
2f7de571
DL
142 */
143static bool retransmits_timed_out(struct sock *sk,
dca43c75 144 unsigned int boundary,
ce682ef6 145 unsigned int timeout)
2f7de571 146{
ce682ef6 147 const unsigned int rto_base = TCP_RTO_MIN;
9a568de4 148 unsigned int linear_backoff_thresh, start_ts;
2f7de571
DL
149
150 if (!inet_csk(sk)->icsk_retransmits)
151 return false;
152
7faee5c0 153 start_ts = tcp_sk(sk)->retrans_stamp;
75c119af
ED
154 if (unlikely(!start_ts)) {
155 struct sk_buff *head = tcp_rtx_queue_head(sk);
156
157 if (!head)
158 return false;
159 start_ts = tcp_skb_timestamp(head);
160 }
2f7de571 161
dca43c75 162 if (likely(timeout == 0)) {
21a180cd 163 linear_backoff_thresh = ilog2(TCP_RTO_MAX/rto_base);
2f7de571 164
dca43c75 165 if (boundary <= linear_backoff_thresh)
21a180cd 166 timeout = ((2 << boundary) - 1) * rto_base;
dca43c75 167 else
21a180cd 168 timeout = ((2 << linear_backoff_thresh) - 1) * rto_base +
dca43c75
JC
169 (boundary - linear_backoff_thresh) * TCP_RTO_MAX;
170 }
9a568de4 171 return (tcp_time_stamp(tcp_sk(sk)) - start_ts) >= jiffies_to_msecs(timeout);
2f7de571
DL
172}
173
1da177e4
LT
174/* A write timeout has occurred. Process the after effects. */
175static int tcp_write_timeout(struct sock *sk)
176{
5d424d5a 177 struct inet_connection_sock *icsk = inet_csk(sk);
c968601d 178 struct tcp_sock *tp = tcp_sk(sk);
6fa25166 179 struct net *net = sock_net(sk);
ce682ef6 180 bool expired, do_reset;
1da177e4
LT
181 int retry_until;
182
183 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
c968601d 184 if (icsk->icsk_retransmits) {
b6c6712a 185 dst_negative_advice(sk);
c968601d 186 if (tp->syn_fastopen || tp->syn_data)
2646c831 187 tcp_fastopen_cache_set(sk, 0, NULL, true, 0);
dd52bc2b 188 if (tp->syn_data && icsk->icsk_retransmits == 1)
c10d9310
ED
189 NET_INC_STATS(sock_net(sk),
190 LINUX_MIB_TCPFASTOPENACTIVEFAIL);
3acf3ec3
LB
191 } else if (!tp->syn_data && !tp->syn_fastopen) {
192 sk_rethink_txhash(sk);
c968601d 193 }
6fa25166 194 retry_until = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_syn_retries;
ce682ef6 195 expired = icsk->icsk_retransmits >= retry_until;
1da177e4 196 } else {
ce682ef6 197 if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1, 0)) {
0e45f4da
YC
198 /* Some middle-boxes may black-hole Fast Open _after_
199 * the handshake. Therefore we conservatively disable
59450f8d
WW
200 * Fast Open on this path on recurring timeouts after
201 * successful Fast Open.
0e45f4da 202 */
59450f8d 203 if (tp->syn_data_acked) {
0e45f4da 204 tcp_fastopen_cache_set(sk, 0, NULL, true, 0);
ae5c3f40 205 if (icsk->icsk_retransmits == net->ipv4.sysctl_tcp_retries1)
c10d9310
ED
206 NET_INC_STATS(sock_net(sk),
207 LINUX_MIB_TCPFASTOPENACTIVEFAIL);
0e45f4da 208 }
5d424d5a 209 /* Black hole detection */
ce55dd36 210 tcp_mtu_probing(icsk, sk);
1da177e4 211
b6c6712a 212 dst_negative_advice(sk);
3acf3ec3
LB
213 } else {
214 sk_rethink_txhash(sk);
1da177e4
LT
215 }
216
c6214a97 217 retry_until = net->ipv4.sysctl_tcp_retries2;
1da177e4 218 if (sock_flag(sk, SOCK_DEAD)) {
7533ce30 219 const bool alive = icsk->icsk_rto < TCP_RTO_MAX;
e905a9ed 220
1da177e4 221 retry_until = tcp_orphan_retries(sk, alive);
6fa12c85 222 do_reset = alive ||
ce682ef6 223 !retransmits_timed_out(sk, retry_until, 0);
1da177e4 224
6fa12c85 225 if (tcp_out_of_resources(sk, do_reset))
1da177e4
LT
226 return 1;
227 }
ce682ef6
ED
228 expired = retransmits_timed_out(sk, retry_until,
229 icsk->icsk_user_timeout);
1da177e4 230 }
ce682ef6 231 if (expired) {
1da177e4
LT
232 /* Has it gone just too far? */
233 tcp_write_err(sk);
234 return 1;
235 }
236 return 0;
237}
238
c10d9310 239/* Called with BH disabled */
6f458dfb 240void tcp_delack_timer_handler(struct sock *sk)
1da177e4 241{
463c84b9 242 struct inet_connection_sock *icsk = inet_csk(sk);
1da177e4 243
9993e7d3 244 sk_mem_reclaim_partial(sk);
1da177e4 245
02b2faaf
ED
246 if (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) ||
247 !(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
1da177e4
LT
248 goto out;
249
463c84b9
ACM
250 if (time_after(icsk->icsk_ack.timeout, jiffies)) {
251 sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout);
1da177e4
LT
252 goto out;
253 }
463c84b9 254 icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER;
1da177e4 255
463c84b9
ACM
256 if (inet_csk_ack_scheduled(sk)) {
257 if (!icsk->icsk_ack.pingpong) {
1da177e4 258 /* Delayed ACK missed: inflate ATO. */
463c84b9 259 icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1, icsk->icsk_rto);
1da177e4
LT
260 } else {
261 /* Delayed ACK missed: leave pingpong mode and
262 * deflate ATO.
263 */
463c84b9
ACM
264 icsk->icsk_ack.pingpong = 0;
265 icsk->icsk_ack.ato = TCP_ATO_MIN;
1da177e4
LT
266 }
267 tcp_send_ack(sk);
02a1d6e7 268 __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKS);
1da177e4 269 }
1da177e4
LT
270
271out:
b8da51eb 272 if (tcp_under_memory_pressure(sk))
3ab224be 273 sk_mem_reclaim(sk);
6f458dfb
ED
274}
275
c380d37e
RS
276
277/**
278 * tcp_delack_timer() - The TCP delayed ACK timeout handler
279 * @data: Pointer to the current socket. (gets casted to struct sock *)
280 *
281 * This function gets (indirectly) called when the kernel timer for a TCP packet
282 * of this socket expires. Calls tcp_delack_timer_handler() to do the actual work.
283 *
284 * Returns: Nothing (void)
285 */
59f379f9 286static void tcp_delack_timer(struct timer_list *t)
6f458dfb 287{
59f379f9
KC
288 struct inet_connection_sock *icsk =
289 from_timer(icsk, t, icsk_delack_timer);
290 struct sock *sk = &icsk->icsk_inet.sk;
6f458dfb
ED
291
292 bh_lock_sock(sk);
293 if (!sock_owned_by_user(sk)) {
294 tcp_delack_timer_handler(sk);
295 } else {
59f379f9 296 icsk->icsk_ack.blocked = 1;
02a1d6e7 297 __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
6f458dfb 298 /* deleguate our work to tcp_release_cb() */
7aa5470c 299 if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &sk->sk_tsq_flags))
144d56e9 300 sock_hold(sk);
6f458dfb 301 }
1da177e4
LT
302 bh_unlock_sock(sk);
303 sock_put(sk);
304}
305
306static void tcp_probe_timer(struct sock *sk)
307{
6687e988 308 struct inet_connection_sock *icsk = inet_csk(sk);
75c119af 309 struct sk_buff *skb = tcp_send_head(sk);
1da177e4
LT
310 struct tcp_sock *tp = tcp_sk(sk);
311 int max_probes;
b248230c 312 u32 start_ts;
1da177e4 313
75c119af 314 if (tp->packets_out || !skb) {
6687e988 315 icsk->icsk_probes_out = 0;
1da177e4
LT
316 return;
317 }
318
b248230c
YC
319 /* RFC 1122 4.2.2.17 requires the sender to stay open indefinitely as
320 * long as the receiver continues to respond probes. We support this by
321 * default and reset icsk_probes_out with incoming ACKs. But if the
322 * socket is orphaned or the user specifies TCP_USER_TIMEOUT, we
323 * kill the socket when the retry count and the time exceeds the
324 * corresponding system limit. We also implement similar policy when
325 * we use RTO to probe window in tcp_retransmit_timer().
1da177e4 326 */
75c119af 327 start_ts = tcp_skb_timestamp(skb);
b248230c 328 if (!start_ts)
75c119af 329 skb->skb_mstamp = tp->tcp_mstamp;
b248230c 330 else if (icsk->icsk_user_timeout &&
4ab68879
ED
331 (s32)(tcp_time_stamp(tp) - start_ts) >
332 jiffies_to_msecs(icsk->icsk_user_timeout))
b248230c 333 goto abort;
1da177e4 334
c6214a97 335 max_probes = sock_net(sk)->ipv4.sysctl_tcp_retries2;
1da177e4 336 if (sock_flag(sk, SOCK_DEAD)) {
7533ce30 337 const bool alive = inet_csk_rto_backoff(icsk, TCP_RTO_MAX) < TCP_RTO_MAX;
e905a9ed 338
1da177e4 339 max_probes = tcp_orphan_retries(sk, alive);
b248230c
YC
340 if (!alive && icsk->icsk_backoff >= max_probes)
341 goto abort;
342 if (tcp_out_of_resources(sk, true))
1da177e4
LT
343 return;
344 }
345
6687e988 346 if (icsk->icsk_probes_out > max_probes) {
b248230c 347abort: tcp_write_err(sk);
1da177e4
LT
348 } else {
349 /* Only send another probe if we didn't close things up. */
350 tcp_send_probe0(sk);
351 }
352}
353
8336886f
JC
354/*
355 * Timer for Fast Open socket to retransmit SYNACK. Note that the
356 * sk here is the child socket, not the parent (listener) socket.
357 */
358static void tcp_fastopen_synack_timer(struct sock *sk)
359{
360 struct inet_connection_sock *icsk = inet_csk(sk);
361 int max_retries = icsk->icsk_syn_retries ? :
7c083ecb 362 sock_net(sk)->ipv4.sysctl_tcp_synack_retries + 1; /* add one more retry for fastopen */
8336886f
JC
363 struct request_sock *req;
364
365 req = tcp_sk(sk)->fastopen_rsk;
42cb80a2 366 req->rsk_ops->syn_ack_timeout(req);
8336886f 367
e6c022a4 368 if (req->num_timeout >= max_retries) {
8336886f
JC
369 tcp_write_err(sk);
370 return;
371 }
372 /* XXX (TFO) - Unlike regular SYN-ACK retransmit, we ignore error
373 * returned from rtx_syn_ack() to make it more persistent like
374 * regular retransmit because if the child socket has been accepted
375 * it's not good to give up too easily.
376 */
e6c022a4
ED
377 inet_rtx_syn_ack(sk, req);
378 req->num_timeout++;
7e32b443 379 icsk->icsk_retransmits++;
8336886f 380 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
e6c022a4 381 TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
8336886f
JC
382}
383
1da177e4 384
c380d37e
RS
385/**
386 * tcp_retransmit_timer() - The TCP retransmit timeout handler
387 * @sk: Pointer to the current socket.
388 *
389 * This function gets called when the kernel timer for a TCP packet
390 * of this socket expires.
391 *
392 * It handles retransmission, timer adjustment and other necesarry measures.
393 *
394 * Returns: Nothing (void)
395 */
f1ecd5d9 396void tcp_retransmit_timer(struct sock *sk)
1da177e4
LT
397{
398 struct tcp_sock *tp = tcp_sk(sk);
ae5c3f40 399 struct net *net = sock_net(sk);
463c84b9 400 struct inet_connection_sock *icsk = inet_csk(sk);
1da177e4 401
8336886f 402 if (tp->fastopen_rsk) {
37561f68
JC
403 WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV &&
404 sk->sk_state != TCP_FIN_WAIT1);
8336886f
JC
405 tcp_fastopen_synack_timer(sk);
406 /* Before we receive ACK to our SYN-ACK don't retransmit
407 * anything else (e.g., data or FIN segments).
408 */
409 return;
410 }
1da177e4
LT
411 if (!tp->packets_out)
412 goto out;
413
75c119af 414 WARN_ON(tcp_rtx_queue_empty(sk));
1da177e4 415
9b717a8d
ND
416 tp->tlp_high_seq = 0;
417
1da177e4
LT
418 if (!tp->snd_wnd && !sock_flag(sk, SOCK_DEAD) &&
419 !((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))) {
420 /* Receiver dastardly shrinks window. Our retransmits
421 * become zero probes, but we should not timeout this
422 * connection. If the socket is an orphan, time it out,
423 * we cannot allow such beasts to hang infinitely.
424 */
569508c9
YH
425 struct inet_sock *inet = inet_sk(sk);
426 if (sk->sk_family == AF_INET) {
ba7a46f1
JP
427 net_dbg_ratelimited("Peer %pI4:%u/%u unexpectedly shrunk window %u:%u (repaired)\n",
428 &inet->inet_daddr,
429 ntohs(inet->inet_dport),
430 inet->inet_num,
431 tp->snd_una, tp->snd_nxt);
1da177e4 432 }
dfd56b8b 433#if IS_ENABLED(CONFIG_IPV6)
569508c9 434 else if (sk->sk_family == AF_INET6) {
ba7a46f1
JP
435 net_dbg_ratelimited("Peer %pI6:%u/%u unexpectedly shrunk window %u:%u (repaired)\n",
436 &sk->sk_v6_daddr,
437 ntohs(inet->inet_dport),
438 inet->inet_num,
439 tp->snd_una, tp->snd_nxt);
569508c9 440 }
1da177e4 441#endif
70eabf0e 442 if (tcp_jiffies32 - tp->rcv_tstamp > TCP_RTO_MAX) {
1da177e4
LT
443 tcp_write_err(sk);
444 goto out;
445 }
5ae344c9 446 tcp_enter_loss(sk);
75c119af 447 tcp_retransmit_skb(sk, tcp_rtx_queue_head(sk), 1);
1da177e4
LT
448 __sk_dst_reset(sk);
449 goto out_reset_timer;
450 }
451
452 if (tcp_write_timeout(sk))
453 goto out;
454
463c84b9 455 if (icsk->icsk_retransmits == 0) {
40b215e5
PE
456 int mib_idx;
457
c60ce4e2 458 if (icsk->icsk_ca_state == TCP_CA_Recovery) {
bc079e9e
IJ
459 if (tcp_is_sack(tp))
460 mib_idx = LINUX_MIB_TCPSACKRECOVERYFAIL;
461 else
462 mib_idx = LINUX_MIB_TCPRENORECOVERYFAIL;
6687e988 463 } else if (icsk->icsk_ca_state == TCP_CA_Loss) {
40b215e5 464 mib_idx = LINUX_MIB_TCPLOSSFAILURES;
c60ce4e2
IJ
465 } else if ((icsk->icsk_ca_state == TCP_CA_Disorder) ||
466 tp->sacked_out) {
467 if (tcp_is_sack(tp))
468 mib_idx = LINUX_MIB_TCPSACKFAILURES;
469 else
470 mib_idx = LINUX_MIB_TCPRENOFAILURES;
1da177e4 471 } else {
40b215e5 472 mib_idx = LINUX_MIB_TCPTIMEOUTS;
1da177e4 473 }
02a1d6e7 474 __NET_INC_STATS(sock_net(sk), mib_idx);
1da177e4
LT
475 }
476
5ae344c9 477 tcp_enter_loss(sk);
1da177e4 478
75c119af 479 if (tcp_retransmit_skb(sk, tcp_rtx_queue_head(sk), 1) > 0) {
1da177e4
LT
480 /* Retransmission failed because of local congestion,
481 * do not backoff.
482 */
463c84b9
ACM
483 if (!icsk->icsk_retransmits)
484 icsk->icsk_retransmits = 1;
485 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
3f421baa
ACM
486 min(icsk->icsk_rto, TCP_RESOURCE_PROBE_INTERVAL),
487 TCP_RTO_MAX);
1da177e4
LT
488 goto out;
489 }
490
491 /* Increase the timeout each time we retransmit. Note that
492 * we do not increase the rtt estimate. rto is initialized
493 * from rtt, but increases here. Jacobson (SIGCOMM 88) suggests
494 * that doubling rto each time is the least we can get away with.
495 * In KA9Q, Karn uses this for the first few times, and then
496 * goes to quadratic. netBSD doubles, but only goes up to *64,
497 * and clamps at 1 to 64 sec afterwards. Note that 120 sec is
498 * defined in the protocol as the maximum possible RTT. I guess
499 * we'll have to use something other than TCP to talk to the
500 * University of Mars.
501 *
502 * PAWS allows us longer timeouts and large windows, so once
503 * implemented ftp to mars will work nicely. We will have to fix
504 * the 120 second clamps though!
505 */
463c84b9
ACM
506 icsk->icsk_backoff++;
507 icsk->icsk_retransmits++;
1da177e4
LT
508
509out_reset_timer:
36e31b0a
AP
510 /* If stream is thin, use linear timeouts. Since 'icsk_backoff' is
511 * used to reset timer, set to 0. Recalculate 'icsk_rto' as this
512 * might be increased if the stream oscillates between thin and thick,
513 * thus the old value might already be too high compared to the value
514 * set by 'tcp_set_rto' in tcp_input.c which resets the rto without
515 * backoff. Limit to TCP_THIN_LINEAR_RETRIES before initiating
516 * exponential backoff behaviour to avoid continue hammering
517 * linear-timeout retransmissions into a black hole
518 */
519 if (sk->sk_state == TCP_ESTABLISHED &&
2c04ac8a 520 (tp->thin_lto || net->ipv4.sysctl_tcp_thin_linear_timeouts) &&
36e31b0a
AP
521 tcp_stream_is_thin(tp) &&
522 icsk->icsk_retransmits <= TCP_THIN_LINEAR_RETRIES) {
523 icsk->icsk_backoff = 0;
524 icsk->icsk_rto = min(__tcp_set_rto(tp), TCP_RTO_MAX);
525 } else {
526 /* Use normal (exponential) backoff */
527 icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX);
528 }
3f421baa 529 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, TCP_RTO_MAX);
ce682ef6 530 if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1 + 1, 0))
1da177e4
LT
531 __sk_dst_reset(sk);
532
533out:;
534}
535
c380d37e
RS
536/* Called with bottom-half processing disabled.
537 Called by tcp_write_timer() */
6f458dfb 538void tcp_write_timer_handler(struct sock *sk)
1da177e4 539{
463c84b9 540 struct inet_connection_sock *icsk = inet_csk(sk);
1da177e4
LT
541 int event;
542
02b2faaf
ED
543 if (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) ||
544 !icsk->icsk_pending)
1da177e4
LT
545 goto out;
546
463c84b9
ACM
547 if (time_after(icsk->icsk_timeout, jiffies)) {
548 sk_reset_timer(sk, &icsk->icsk_retransmit_timer, icsk->icsk_timeout);
1da177e4
LT
549 goto out;
550 }
551
9a568de4 552 tcp_mstamp_refresh(tcp_sk(sk));
463c84b9 553 event = icsk->icsk_pending;
1da177e4
LT
554
555 switch (event) {
57dde7f7
YC
556 case ICSK_TIME_REO_TIMEOUT:
557 tcp_rack_reo_timeout(sk);
558 break;
6ba8a3b1
ND
559 case ICSK_TIME_LOSS_PROBE:
560 tcp_send_loss_probe(sk);
561 break;
463c84b9 562 case ICSK_TIME_RETRANS:
6ba8a3b1 563 icsk->icsk_pending = 0;
1da177e4
LT
564 tcp_retransmit_timer(sk);
565 break;
463c84b9 566 case ICSK_TIME_PROBE0:
6ba8a3b1 567 icsk->icsk_pending = 0;
1da177e4
LT
568 tcp_probe_timer(sk);
569 break;
570 }
1da177e4
LT
571
572out:
3ab224be 573 sk_mem_reclaim(sk);
6f458dfb
ED
574}
575
59f379f9 576static void tcp_write_timer(struct timer_list *t)
6f458dfb 577{
59f379f9
KC
578 struct inet_connection_sock *icsk =
579 from_timer(icsk, t, icsk_retransmit_timer);
580 struct sock *sk = &icsk->icsk_inet.sk;
6f458dfb
ED
581
582 bh_lock_sock(sk);
583 if (!sock_owned_by_user(sk)) {
584 tcp_write_timer_handler(sk);
585 } else {
c380d37e 586 /* delegate our work to tcp_release_cb() */
7aa5470c 587 if (!test_and_set_bit(TCP_WRITE_TIMER_DEFERRED, &sk->sk_tsq_flags))
144d56e9 588 sock_hold(sk);
6f458dfb 589 }
1da177e4
LT
590 bh_unlock_sock(sk);
591 sock_put(sk);
592}
593
42cb80a2 594void tcp_syn_ack_timeout(const struct request_sock *req)
72659ecc 595{
42cb80a2
ED
596 struct net *net = read_pnet(&inet_rsk(req)->ireq_net);
597
02a1d6e7 598 __NET_INC_STATS(net, LINUX_MIB_TCPTIMEOUTS);
72659ecc
OP
599}
600EXPORT_SYMBOL(tcp_syn_ack_timeout);
601
1da177e4
LT
602void tcp_set_keepalive(struct sock *sk, int val)
603{
604 if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))
605 return;
606
607 if (val && !sock_flag(sk, SOCK_KEEPOPEN))
463c84b9 608 inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tcp_sk(sk)));
1da177e4 609 else if (!val)
463c84b9 610 inet_csk_delete_keepalive_timer(sk);
1da177e4 611}
4b9d07a4 612EXPORT_SYMBOL_GPL(tcp_set_keepalive);
1da177e4
LT
613
614
59f379f9 615static void tcp_keepalive_timer (struct timer_list *t)
1da177e4 616{
59f379f9 617 struct sock *sk = from_timer(sk, t, sk_timer);
6687e988 618 struct inet_connection_sock *icsk = inet_csk(sk);
1da177e4 619 struct tcp_sock *tp = tcp_sk(sk);
6c37e5de 620 u32 elapsed;
1da177e4
LT
621
622 /* Only process if socket is not in use. */
623 bh_lock_sock(sk);
624 if (sock_owned_by_user(sk)) {
e905a9ed 625 /* Try again later. */
463c84b9 626 inet_csk_reset_keepalive_timer (sk, HZ/20);
1da177e4
LT
627 goto out;
628 }
629
630 if (sk->sk_state == TCP_LISTEN) {
fa76ce73 631 pr_err("Hmm... keepalive on a LISTEN ???\n");
1da177e4
LT
632 goto out;
633 }
634
635 if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) {
636 if (tp->linger2 >= 0) {
463c84b9 637 const int tmo = tcp_fin_time(sk) - TCP_TIMEWAIT_LEN;
1da177e4
LT
638
639 if (tmo > 0) {
640 tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
641 goto out;
642 }
643 }
644 tcp_send_active_reset(sk, GFP_ATOMIC);
645 goto death;
646 }
647
2dda6400
ED
648 if (!sock_flag(sk, SOCK_KEEPOPEN) ||
649 ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_SYN_SENT)))
1da177e4
LT
650 goto out;
651
652 elapsed = keepalive_time_when(tp);
653
654 /* It is alive without keepalive 8) */
75c119af 655 if (tp->packets_out || !tcp_write_queue_empty(sk))
1da177e4
LT
656 goto resched;
657
6c37e5de 658 elapsed = keepalive_time_elapsed(tp);
1da177e4
LT
659
660 if (elapsed >= keepalive_time_when(tp)) {
dca43c75
JC
661 /* If the TCP_USER_TIMEOUT option is enabled, use that
662 * to determine when to timeout instead.
663 */
664 if ((icsk->icsk_user_timeout != 0 &&
665 elapsed >= icsk->icsk_user_timeout &&
666 icsk->icsk_probes_out > 0) ||
667 (icsk->icsk_user_timeout == 0 &&
668 icsk->icsk_probes_out >= keepalive_probes(tp))) {
1da177e4
LT
669 tcp_send_active_reset(sk, GFP_ATOMIC);
670 tcp_write_err(sk);
671 goto out;
672 }
e520af48 673 if (tcp_write_wakeup(sk, LINUX_MIB_TCPKEEPALIVE) <= 0) {
6687e988 674 icsk->icsk_probes_out++;
1da177e4
LT
675 elapsed = keepalive_intvl_when(tp);
676 } else {
677 /* If keepalive was lost due to local congestion,
678 * try harder.
679 */
680 elapsed = TCP_RESOURCE_PROBE_INTERVAL;
681 }
682 } else {
683 /* It is tp->rcv_tstamp + keepalive_time_when(tp) */
684 elapsed = keepalive_time_when(tp) - elapsed;
685 }
686
3ab224be 687 sk_mem_reclaim(sk);
1da177e4
LT
688
689resched:
463c84b9 690 inet_csk_reset_keepalive_timer (sk, elapsed);
1da177e4
LT
691 goto out;
692
e905a9ed 693death:
1da177e4
LT
694 tcp_done(sk);
695
696out:
697 bh_unlock_sock(sk);
698 sock_put(sk);
699}
6f458dfb
ED
700
701void tcp_init_xmit_timers(struct sock *sk)
702{
703 inet_csk_init_xmit_timers(sk, &tcp_write_timer, &tcp_delack_timer,
704 &tcp_keepalive_timer);
218af599
ED
705 hrtimer_init(&tcp_sk(sk)->pacing_timer, CLOCK_MONOTONIC,
706 HRTIMER_MODE_ABS_PINNED);
707 tcp_sk(sk)->pacing_timer.function = tcp_pace_kick;
6f458dfb 708}