Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 | /*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* Implementation of the Transmission Control Protocol(TCP).
*
* Version: $Id: tcp_timer.c,v 1.58 1999/03/14 19:48:30 davem Exp $
*
* Authors: Ross Biro, <bir7@leland.Stanford.Edu>
* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
* Mark Evans, <evansmp@uhura.aston.ac.uk>
* Corey Minyard <wf-rch!minyard@relay.EU.net>
* Florian La Roche, <flla@stud.uni-sb.de>
* Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
* Linus Torvalds, <torvalds@cs.helsinki.fi>
* Alan Cox, <gw4pts@gw4pts.ampr.org>
* Matthew Dillon, <dillon@apollo.west.oic.com>
* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
* Jorge Cwik, <jorge@laser.satlink.net>
*/
#include <net/tcp.h>
int sysctl_tcp_syn_retries = TCP_SYN_RETRIES;
int sysctl_tcp_keepalive_time = TCP_KEEPALIVE_TIME;
int sysctl_tcp_keepalive_probes = TCP_KEEPALIVE_PROBES;
int sysctl_tcp_retries1 = TCP_RETR1;
int sysctl_tcp_retries2 = TCP_RETR2;
static void tcp_sltimer_handler(unsigned long);
static void tcp_syn_recv_timer(unsigned long);
static void tcp_keepalive(unsigned long data);
static void tcp_bucketgc(unsigned long);
static void tcp_twkill(unsigned long);
struct timer_list tcp_slow_timer = {
NULL, NULL,
0, 0,
tcp_sltimer_handler,
};
struct tcp_sl_timer tcp_slt_array[TCP_SLT_MAX] = {
{ATOMIC_INIT(0), TCP_SYNACK_PERIOD, 0, tcp_syn_recv_timer},/* SYNACK */
{ATOMIC_INIT(0), TCP_KEEPALIVE_PERIOD, 0, tcp_keepalive}, /* KEEPALIVE */
{ATOMIC_INIT(0), TCP_TWKILL_PERIOD, 0, tcp_twkill}, /* TWKILL */
{ATOMIC_INIT(0), TCP_BUCKETGC_PERIOD, 0, tcp_bucketgc} /* BUCKETGC */
};
const char timer_bug_msg[] = KERN_DEBUG "tcpbug: unknown timer value\n";
/*
* Using different timers for retransmit, delayed acks and probes
* We may wish use just one timer maintaining a list of expire jiffies
* to optimize.
*/
void tcp_init_xmit_timers(struct sock *sk)
{
init_timer(&sk->tp_pinfo.af_tcp.retransmit_timer);
sk->tp_pinfo.af_tcp.retransmit_timer.function=&tcp_retransmit_timer;
sk->tp_pinfo.af_tcp.retransmit_timer.data = (unsigned long) sk;
init_timer(&sk->tp_pinfo.af_tcp.delack_timer);
sk->tp_pinfo.af_tcp.delack_timer.function=&tcp_delack_timer;
sk->tp_pinfo.af_tcp.delack_timer.data = (unsigned long) sk;
init_timer(&sk->tp_pinfo.af_tcp.probe_timer);
sk->tp_pinfo.af_tcp.probe_timer.function=&tcp_probe_timer;
sk->tp_pinfo.af_tcp.probe_timer.data = (unsigned long) sk;
}
/*
* Reset the retransmission timer
*/
void tcp_reset_xmit_timer(struct sock *sk, int what, unsigned long when)
{
struct tcp_opt *tp = &sk->tp_pinfo.af_tcp;
switch (what) {
case TIME_RETRANS:
/* When seting the transmit timer the probe timer
* should not be set.
* The delayed ack timer can be set if we are changing the
* retransmit timer when removing acked frames.
*/
if(tp->probe_timer.prev)
del_timer(&tp->probe_timer);
mod_timer(&tp->retransmit_timer, jiffies+when);
break;
case TIME_DACK:
mod_timer(&tp->delack_timer, jiffies+when);
break;
case TIME_PROBE0:
mod_timer(&tp->probe_timer, jiffies+when);
break;
case TIME_WRITE:
printk(KERN_DEBUG "bug: tcp_reset_xmit_timer TIME_WRITE\n");
break;
default:
printk(KERN_DEBUG "bug: unknown timer value\n");
};
}
void tcp_clear_xmit_timers(struct sock *sk)
{
struct tcp_opt *tp = &sk->tp_pinfo.af_tcp;
if(tp->retransmit_timer.prev)
del_timer(&tp->retransmit_timer);
if(tp->delack_timer.prev)
del_timer(&tp->delack_timer);
if(tp->probe_timer.prev)
del_timer(&tp->probe_timer);
}
static int tcp_write_err(struct sock *sk, int force)
{
sk->err = sk->err_soft ? sk->err_soft : ETIMEDOUT;
sk->error_report(sk);
tcp_clear_xmit_timers(sk);
/* Time wait the socket. */
if (!force && ((1<<sk->state) & (TCPF_FIN_WAIT1|TCPF_FIN_WAIT2|TCPF_CLOSING))) {
tcp_time_wait(sk);
} else {
/* Clean up time. */
tcp_set_state(sk, TCP_CLOSE);
return 0;
}
return 1;
}
/* A write timeout has occurred. Process the after effects. */
static int tcp_write_timeout(struct sock *sk)
{
struct tcp_opt *tp = &(sk->tp_pinfo.af_tcp);
/* Look for a 'soft' timeout. */
if ((sk->state == TCP_ESTABLISHED &&
tp->retransmits && (tp->retransmits % TCP_QUICK_TRIES) == 0) ||
(sk->state != TCP_ESTABLISHED && tp->retransmits > sysctl_tcp_retries1)) {
dst_negative_advice(&sk->dst_cache);
}
/* Have we tried to SYN too many times (repent repent 8)) */
if(tp->retransmits > sysctl_tcp_syn_retries && sk->state==TCP_SYN_SENT) {
tcp_write_err(sk, 1);
/* Don't FIN, we got nothing back */
return 0;
}
/* Has it gone just too far? */
if (tp->retransmits > sysctl_tcp_retries2)
return tcp_write_err(sk, 0);
return 1;
}
void tcp_delack_timer(unsigned long data)
{
struct sock *sk = (struct sock*)data;
if(!sk->zapped &&
sk->tp_pinfo.af_tcp.delayed_acks &&
sk->state != TCP_CLOSE) {
/* If socket is currently locked, defer the ACK. */
if (!atomic_read(&sk->sock_readers))
tcp_send_ack(sk);
else
tcp_send_delayed_ack(&(sk->tp_pinfo.af_tcp), HZ/10);
}
}
void tcp_probe_timer(unsigned long data)
{
struct sock *sk = (struct sock*)data;
struct tcp_opt *tp = &sk->tp_pinfo.af_tcp;
if(sk->zapped)
return;
if (atomic_read(&sk->sock_readers)) {
/* Try again later. */
tcp_reset_xmit_timer(sk, TIME_PROBE0, HZ/5);
return;
}
/* *WARNING* RFC 1122 forbids this
* It doesn't AFAIK, because we kill the retransmit timer -AK
* FIXME: We ought not to do it, Solaris 2.5 actually has fixing
* this behaviour in Solaris down as a bug fix. [AC]
*/
if (tp->probes_out > sysctl_tcp_retries2) {
if(sk->err_soft)
sk->err = sk->err_soft;
else
sk->err = ETIMEDOUT;
sk->error_report(sk);
if ((1<<sk->state) & (TCPF_FIN_WAIT1|TCPF_FIN_WAIT2|TCPF_CLOSING)) {
/* Time wait the socket. */
tcp_time_wait(sk);
} else {
/* Clean up time. */
tcp_set_state(sk, TCP_CLOSE);
}
} else {
/* Only send another probe if we didn't close things up. */
tcp_send_probe0(sk);
}
}
static __inline__ int tcp_keepopen_proc(struct sock *sk)
{
int res = 0;
if ((1<<sk->state) & (TCPF_ESTABLISHED|TCPF_CLOSE_WAIT|TCPF_FIN_WAIT2)) {
struct tcp_opt *tp = &sk->tp_pinfo.af_tcp;
__u32 elapsed = jiffies - tp->rcv_tstamp;
if (elapsed >= sysctl_tcp_keepalive_time) {
if (tp->probes_out > sysctl_tcp_keepalive_probes) {
if(sk->err_soft)
sk->err = sk->err_soft;
else
sk->err = ETIMEDOUT;
tcp_set_state(sk, TCP_CLOSE);
sk->shutdown = SHUTDOWN_MASK;
if (!sk->dead)
sk->state_change(sk);
} else {
tp->probes_out++;
tp->pending = TIME_KEEPOPEN;
tcp_write_wakeup(sk);
res = 1;
}
}
}
return res;
}
/* Garbage collect TCP bind buckets. */
static void tcp_bucketgc(unsigned long data)
{
int i, reaped = 0;;
for(i = 0; i < TCP_BHTABLE_SIZE; i++) {
struct tcp_bind_bucket *tb = tcp_bound_hash[i];
while(tb) {
struct tcp_bind_bucket *next = tb->next;
if((tb->owners == NULL) &&
!(tb->flags & TCPB_FLAG_LOCKED)) {
reaped++;
/* Unlink bucket. */
if(tb->next)
tb->next->pprev = tb->pprev;
*tb->pprev = tb->next;
/* Finally, free it up. */
kmem_cache_free(tcp_bucket_cachep, tb);
}
tb = next;
}
}
if(reaped != 0) {
struct tcp_sl_timer *slt = (struct tcp_sl_timer *)data;
/* Eat timer references. */
atomic_sub(reaped, &slt->count);
}
}
/* Kill off TIME_WAIT sockets once their lifetime has expired. */
int tcp_tw_death_row_slot = 0;
static struct tcp_tw_bucket *tcp_tw_death_row[TCP_TWKILL_SLOTS] =
{ NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL };
extern void tcp_timewait_kill(struct tcp_tw_bucket *tw);
static void tcp_twkill(unsigned long data)
{
struct tcp_tw_bucket *tw;
int killed = 0;
tw = tcp_tw_death_row[tcp_tw_death_row_slot];
tcp_tw_death_row[tcp_tw_death_row_slot] = NULL;
while(tw != NULL) {
struct tcp_tw_bucket *next = tw->next_death;
tcp_timewait_kill(tw);
killed++;
tw = next;
}
if(killed != 0) {
struct tcp_sl_timer *slt = (struct tcp_sl_timer *)data;
atomic_sub(killed, &slt->count);
}
tcp_tw_death_row_slot =
((tcp_tw_death_row_slot + 1) & (TCP_TWKILL_SLOTS - 1));
}
/* These are always called from BH context. See callers in
* tcp_input.c to verify this.
*/
void tcp_tw_schedule(struct tcp_tw_bucket *tw)
{
int slot = (tcp_tw_death_row_slot - 1) & (TCP_TWKILL_SLOTS - 1);
tw->death_slot = slot;
tw->next_death = tcp_tw_death_row[slot];
tcp_tw_death_row[slot] = tw;
tcp_inc_slow_timer(TCP_SLT_TWKILL);
}
/* Happens rarely if at all, no care about scalability here. */
void tcp_tw_reschedule(struct tcp_tw_bucket *tw)
{
struct tcp_tw_bucket *walk;
int slot = tw->death_slot;
walk = tcp_tw_death_row[slot];
if(walk == tw) {
tcp_tw_death_row[slot] = tw->next_death;
} else {
while(walk->next_death != tw)
walk = walk->next_death;
walk->next_death = tw->next_death;
}
slot = (tcp_tw_death_row_slot - 1) & (TCP_TWKILL_SLOTS - 1);
tw->death_slot = slot;
tw->next_death = tcp_tw_death_row[slot];
tcp_tw_death_row[slot] = tw;
/* Timer was incremented when we first entered the table. */
}
/* This is for handling early-kills of TIME_WAIT sockets. */
void tcp_tw_deschedule(struct tcp_tw_bucket *tw)
{
struct tcp_tw_bucket *walk;
int slot = tw->death_slot;
walk = tcp_tw_death_row[slot];
if(walk == tw) {
tcp_tw_death_row[slot] = tw->next_death;
} else {
while(walk->next_death != tw)
walk = walk->next_death;
walk->next_death = tw->next_death;
}
tcp_dec_slow_timer(TCP_SLT_TWKILL);
}
/*
* Check all sockets for keepalive timer
* Called every 75 seconds
* This timer is started by af_inet init routine and is constantly
* running.
*
* It might be better to maintain a count of sockets that need it using
* setsockopt/tcp_destroy_sk and only set the timer when needed.
*/
/*
* don't send over 5 keepopens at a time to avoid burstiness
* on big servers [AC]
*/
#define MAX_KA_PROBES 5
int sysctl_tcp_max_ka_probes = MAX_KA_PROBES;
/* Keepopen's are only valid for "established" TCP's, nicely our listener
* hash gets rid of most of the useless testing, so we run through a couple
* of the established hash chains each clock tick. -DaveM
*
* And now, even more magic... TIME_WAIT TCP's cannot have keepalive probes
* going off for them, so we only need check the first half of the established
* hash table, even less testing under heavy load.
*
* I _really_ would rather do this by adding a new timer_struct to struct sock,
* and this way only those who set the keepalive option will get the overhead.
* The idea is you set it for 2 hours when the sock is first connected, when it
* does fire off (if at all, most sockets die earlier) you check for the keepalive
* option and also if the sock has been idle long enough to start probing.
*/
static void tcp_keepalive(unsigned long data)
{
static int chain_start = 0;
int count = 0;
int i;
for(i = chain_start; i < (chain_start + ((TCP_HTABLE_SIZE/2) >> 2)); i++) {
struct sock *sk = tcp_established_hash[i];
while(sk) {
if(sk->keepopen) {
count += tcp_keepopen_proc(sk);
if(count == sysctl_tcp_max_ka_probes)
goto out;
}
sk = sk->next;
}
}
out:
chain_start = ((chain_start + ((TCP_HTABLE_SIZE/2)>>2)) &
((TCP_HTABLE_SIZE/2) - 1));
}
/*
* The TCP retransmit timer. This lacks a few small details.
*
* 1. An initial rtt timeout on the probe0 should cause what we can
* of the first write queue buffer to be split and sent.
* 2. On a 'major timeout' as defined by RFC1122 we shouldn't report
* ETIMEDOUT if we know an additional 'soft' error caused this.
* tcp_err should save a 'soft error' for us.
* [Unless someone has broken it then it does, except for one 2.0
* broken case of a send when the route/device is directly unreachable,
* and we error but should retry! - FIXME] [AC]
*/
void tcp_retransmit_timer(unsigned long data)
{
struct sock *sk = (struct sock*)data;
struct tcp_opt *tp = &sk->tp_pinfo.af_tcp;
/* We are reset. We will send no more retransmits. */
if(sk->zapped) {
tcp_clear_xmit_timer(sk, TIME_RETRANS);
return;
}
if (atomic_read(&sk->sock_readers)) {
/* Try again later */
tcp_reset_xmit_timer(sk, TIME_RETRANS, HZ/20);
return;
}
/* Clear delay ack timer. */
tcp_clear_xmit_timer(sk, TIME_DACK);
/* RFC 2018, clear all 'sacked' flags in retransmission queue,
* the sender may have dropped out of order frames and we must
* send them out should this timer fire on us.
*/
if(tp->sack_ok) {
struct sk_buff *skb = skb_peek(&sk->write_queue);
while((skb != NULL) &&
(skb != tp->send_head) &&
(skb != (struct sk_buff *)&sk->write_queue)) {
TCP_SKB_CB(skb)->sacked &=
~(TCPCB_SACKED_ACKED | TCPCB_SACKED_RETRANS);
skb = skb->next;
}
}
/* Retransmission. */
tp->retrans_head = NULL;
tp->rexmt_done = 0;
tp->fackets_out = 0;
tp->retrans_out = 0;
if (tp->retransmits == 0) {
/* Remember window where we lost:
* "one half of the current window but at least 2 segments"
*
* Here "current window" means the effective one, which
* means it must be an accurate representation of our current
* sending rate _and_ the snd_wnd.
*/
tp->snd_ssthresh = max(min(tp->snd_wnd, tp->snd_cwnd) >> 1, 2);
tp->snd_cwnd_cnt = 0;
tp->snd_cwnd = 1;
}
tp->retransmits++;
tp->dup_acks = 0;
tp->high_seq = tp->snd_nxt;
tcp_retransmit_skb(sk, skb_peek(&sk->write_queue));
/* Increase the timeout each time we retransmit. Note that
* we do not increase the rtt estimate. rto is initialized
* from rtt, but increases here. Jacobson (SIGCOMM 88) suggests
* that doubling rto each time is the least we can get away with.
* In KA9Q, Karn uses this for the first few times, and then
* goes to quadratic. netBSD doubles, but only goes up to *64,
* and clamps at 1 to 64 sec afterwards. Note that 120 sec is
* defined in the protocol as the maximum possible RTT. I guess
* we'll have to use something other than TCP to talk to the
* University of Mars.
*
* PAWS allows us longer timeouts and large windows, so once
* implemented ftp to mars will work nicely. We will have to fix
* the 120 second clamps though!
*/
tp->backoff++;
tp->rto = min(tp->rto << 1, 120*HZ);
tcp_reset_xmit_timer(sk, TIME_RETRANS, tp->rto);
tcp_write_timeout(sk);
}
/*
* Slow timer for SYN-RECV sockets
*/
/* This now scales very nicely. -DaveM */
static void tcp_syn_recv_timer(unsigned long data)
{
struct sock *sk;
unsigned long now = jiffies;
int i;
for(i = 0; i < TCP_LHTABLE_SIZE; i++) {
sk = tcp_listening_hash[i];
while(sk) {
struct tcp_opt *tp = &sk->tp_pinfo.af_tcp;
/* TCP_LISTEN is implied. */
if (!atomic_read(&sk->sock_readers) && tp->syn_wait_queue) {
struct open_request *prev = (struct open_request *)(&tp->syn_wait_queue);
struct open_request *req = tp->syn_wait_queue;
do {
struct open_request *conn;
conn = req;
req = req->dl_next;
if (conn->sk) {
prev = conn;
continue;
}
if ((long)(now - conn->expires) <= 0)
break;
tcp_synq_unlink(tp, conn, prev);
if (conn->retrans >= sysctl_tcp_retries1) {
#ifdef TCP_DEBUG
printk(KERN_DEBUG "syn_recv: "
"too many retransmits\n");
#endif
(*conn->class->destructor)(conn);
tcp_dec_slow_timer(TCP_SLT_SYNACK);
tp->syn_backlog--;
tcp_openreq_free(conn);
if (!tp->syn_wait_queue)
break;
} else {
__u32 timeo;
struct open_request *op;
(*conn->class->rtx_syn_ack)(sk, conn);
conn->retrans++;
#ifdef TCP_DEBUG
printk(KERN_DEBUG "syn_ack rtx %d\n",
conn->retrans);
#endif
timeo = min((TCP_TIMEOUT_INIT
<< conn->retrans),
120*HZ);
conn->expires = now + timeo;
op = prev->dl_next;
tcp_synq_queue(tp, conn);
if (op != prev->dl_next)
prev = prev->dl_next;
}
/* old prev still valid here */
} while (req);
}
sk = sk->next;
}
}
}
void tcp_sltimer_handler(unsigned long data)
{
struct tcp_sl_timer *slt = tcp_slt_array;
unsigned long next = ~0UL;
unsigned long now = jiffies;
int i;
for (i=0; i < TCP_SLT_MAX; i++, slt++) {
if (atomic_read(&slt->count)) {
long trigger;
trigger = slt->period - ((long)(now - slt->last));
if (trigger <= 0) {
(*slt->handler)((unsigned long) slt);
slt->last = now;
trigger = slt->period;
}
/* Only reschedule if some events remain. */
if (atomic_read(&slt->count))
next = min(next, trigger);
}
}
if (next != ~0UL)
mod_timer(&tcp_slow_timer, (now + next));
}
void __tcp_inc_slow_timer(struct tcp_sl_timer *slt)
{
unsigned long now = jiffies;
unsigned long when;
slt->last = now;
when = now + slt->period;
if (tcp_slow_timer.prev) {
if ((long)(tcp_slow_timer.expires - when) >= 0)
mod_timer(&tcp_slow_timer, when);
} else {
tcp_slow_timer.expires = when;
add_timer(&tcp_slow_timer);
}
}
|