tcp_timer.c revision 1.90
1/* $NetBSD: tcp_timer.c,v 1.90 2016/04/26 08:44:44 ozaki-r Exp $ */ 2 3/* 4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the project nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32/*- 33 * Copyright (c) 1997, 1998, 2001, 2005 The NetBSD Foundation, Inc. 34 * All rights reserved. 35 * 36 * This code is derived from software contributed to The NetBSD Foundation 37 * by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation 38 * Facility, NASA Ames Research Center. 39 * This code is derived from software contributed to The NetBSD Foundation 40 * by Charles M. Hannum. 41 * 42 * Redistribution and use in source and binary forms, with or without 43 * modification, are permitted provided that the following conditions 44 * are met: 45 * 1. Redistributions of source code must retain the above copyright 46 * notice, this list of conditions and the following disclaimer. 47 * 2. Redistributions in binary form must reproduce the above copyright 48 * notice, this list of conditions and the following disclaimer in the 49 * documentation and/or other materials provided with the distribution. 50 * 51 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 52 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 53 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 54 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 55 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 56 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 57 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 58 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 59 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 60 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 61 * POSSIBILITY OF SUCH DAMAGE. 62 */ 63 64/* 65 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 66 * The Regents of the University of California. All rights reserved. 67 * 68 * Redistribution and use in source and binary forms, with or without 69 * modification, are permitted provided that the following conditions 70 * are met: 71 * 1. Redistributions of source code must retain the above copyright 72 * notice, this list of conditions and the following disclaimer. 73 * 2. Redistributions in binary form must reproduce the above copyright 74 * notice, this list of conditions and the following disclaimer in the 75 * documentation and/or other materials provided with the distribution. 76 * 3. Neither the name of the University nor the names of its contributors 77 * may be used to endorse or promote products derived from this software 78 * without specific prior written permission. 79 * 80 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 81 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 82 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 83 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 84 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 85 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 86 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 87 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 88 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 89 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 90 * SUCH DAMAGE. 91 * 92 * @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95 93 */ 94 95#include <sys/cdefs.h> 96__KERNEL_RCSID(0, "$NetBSD: tcp_timer.c,v 1.90 2016/04/26 08:44:44 ozaki-r Exp $"); 97 98#ifdef _KERNEL_OPT 99#include "opt_inet.h" 100#include "opt_tcp_debug.h" 101#endif 102 103#include <sys/param.h> 104#include <sys/systm.h> 105#include <sys/mbuf.h> 106#include <sys/socket.h> 107#include <sys/socketvar.h> 108#include <sys/protosw.h> 109#include <sys/errno.h> 110#include <sys/kernel.h> 111 112#include <net/if.h> 113 114#include <netinet/in.h> 115#include <netinet/in_systm.h> 116#include <netinet/ip.h> 117#include <netinet/in_pcb.h> 118#include <netinet/ip_var.h> 119#include <netinet/ip_icmp.h> 120 121#ifdef INET6 122#ifndef INET 123#include <netinet/in.h> 124#endif 125#include <netinet/ip6.h> 126#include <netinet6/in6_pcb.h> 127#endif 128 129#include <netinet/tcp.h> 130#include <netinet/tcp_fsm.h> 131#include <netinet/tcp_seq.h> 132#include <netinet/tcp_timer.h> 133#include <netinet/tcp_var.h> 134#include <netinet/tcp_private.h> 135#include <netinet/tcp_congctl.h> 136#include <netinet/tcpip.h> 137#ifdef TCP_DEBUG 138#include <netinet/tcp_debug.h> 139#endif 140 141/* 142 * Various tunable timer parameters. These are initialized in tcp_init(), 143 * unless they are patched. 144 */ 145u_int tcp_keepinit = 0; 146u_int tcp_keepidle = 0; 147u_int tcp_keepintvl = 0; 148u_int tcp_keepcnt = 0; /* max idle probes */ 149 150int tcp_maxpersistidle = 0; /* max idle time in persist */ 151 152/* 153 * Time to delay the ACK. This is initialized in tcp_init(), unless 154 * its patched. 155 */ 156int tcp_delack_ticks = 0; 157 158void tcp_timer_rexmt(void *); 159void tcp_timer_persist(void *); 160void tcp_timer_keep(void *); 161void tcp_timer_2msl(void *); 162 163const tcp_timer_func_t tcp_timer_funcs[TCPT_NTIMERS] = { 164 tcp_timer_rexmt, 165 tcp_timer_persist, 166 tcp_timer_keep, 167 tcp_timer_2msl, 168}; 169 170/* 171 * Timer state initialization, called from tcp_init(). 172 */ 173void 174tcp_timer_init(void) 175{ 176 177 if (tcp_keepinit == 0) 178 tcp_keepinit = TCPTV_KEEP_INIT; 179 180 if (tcp_keepidle == 0) 181 tcp_keepidle = TCPTV_KEEP_IDLE; 182 183 if (tcp_keepintvl == 0) 184 tcp_keepintvl = TCPTV_KEEPINTVL; 185 186 if (tcp_keepcnt == 0) 187 tcp_keepcnt = TCPTV_KEEPCNT; 188 189 if (tcp_maxpersistidle == 0) 190 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 191 192 if (tcp_delack_ticks == 0) 193 tcp_delack_ticks = TCP_DELACK_TICKS; 194} 195 196/* 197 * Callout to process delayed ACKs for a TCPCB. 198 */ 199void 200tcp_delack(void *arg) 201{ 202 struct tcpcb *tp = arg; 203 204 /* 205 * If tcp_output() wasn't able to transmit the ACK 206 * for whatever reason, it will restart the delayed 207 * ACK callout. 208 */ 209 210 mutex_enter(softnet_lock); 211 if ((tp->t_flags & (TF_DEAD | TF_DELACK)) != TF_DELACK) { 212 mutex_exit(softnet_lock); 213 return; 214 } 215 if (!callout_expired(&tp->t_delack_ch)) { 216 mutex_exit(softnet_lock); 217 return; 218 } 219 220 tp->t_flags |= TF_ACKNOW; 221 KERNEL_LOCK(1, NULL); 222 (void) tcp_output(tp); 223 KERNEL_UNLOCK_ONE(NULL); 224 mutex_exit(softnet_lock); 225} 226 227/* 228 * Tcp protocol timeout routine called every 500 ms. 229 * Updates the timers in all active tcb's and 230 * causes finite state machine actions if timers expire. 231 */ 232void 233tcp_slowtimo(void *arg) 234{ 235 236 mutex_enter(softnet_lock); 237 tcp_iss_seq += TCP_ISSINCR; /* increment iss */ 238 tcp_now++; /* for timestamps */ 239 mutex_exit(softnet_lock); 240 241 callout_schedule(&tcp_slowtimo_ch, hz / PR_SLOWHZ); 242} 243 244/* 245 * Cancel all timers for TCP tp. 246 */ 247void 248tcp_canceltimers(struct tcpcb *tp) 249{ 250 int i; 251 252 for (i = 0; i < TCPT_NTIMERS; i++) 253 TCP_TIMER_DISARM(tp, i); 254} 255 256const int tcp_backoff[TCP_MAXRXTSHIFT + 1] = 257 { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 }; 258 259const int tcp_totbackoff = 511; /* sum of tcp_backoff[] */ 260 261/* 262 * TCP timer processing. 263 */ 264 265void 266tcp_timer_rexmt(void *arg) 267{ 268 struct tcpcb *tp = arg; 269 uint32_t rto; 270#ifdef TCP_DEBUG 271 struct socket *so = NULL; 272 short ostate; 273#endif 274 275 mutex_enter(softnet_lock); 276 if ((tp->t_flags & TF_DEAD) != 0) { 277 mutex_exit(softnet_lock); 278 return; 279 } 280 if (!callout_expired(&tp->t_timer[TCPT_REXMT])) { 281 mutex_exit(softnet_lock); 282 return; 283 } 284 285 KERNEL_LOCK(1, NULL); 286 if ((tp->t_flags & TF_PMTUD_PEND) && tp->t_inpcb && 287 SEQ_GEQ(tp->t_pmtud_th_seq, tp->snd_una) && 288 SEQ_LT(tp->t_pmtud_th_seq, (int)(tp->snd_una + tp->t_ourmss))) { 289 extern struct sockaddr_in icmpsrc; 290 struct icmp icmp; 291 292 tp->t_flags &= ~TF_PMTUD_PEND; 293 294 /* XXX create fake icmp message with relevant entries */ 295 icmp.icmp_nextmtu = tp->t_pmtud_nextmtu; 296 icmp.icmp_ip.ip_len = tp->t_pmtud_ip_len; 297 icmp.icmp_ip.ip_hl = tp->t_pmtud_ip_hl; 298 icmpsrc.sin_addr = tp->t_inpcb->inp_faddr; 299 icmp_mtudisc(&icmp, icmpsrc.sin_addr); 300 301 /* 302 * Notify all connections to the same peer about 303 * new mss and trigger retransmit. 304 */ 305 in_pcbnotifyall(&tcbtable, icmpsrc.sin_addr, EMSGSIZE, 306 tcp_mtudisc); 307 KERNEL_UNLOCK_ONE(NULL); 308 mutex_exit(softnet_lock); 309 return; 310 } 311#ifdef TCP_DEBUG 312#ifdef INET 313 if (tp->t_inpcb) 314 so = tp->t_inpcb->inp_socket; 315#endif 316#ifdef INET6 317 if (tp->t_in6pcb) 318 so = tp->t_in6pcb->in6p_socket; 319#endif 320 ostate = tp->t_state; 321#endif /* TCP_DEBUG */ 322 323 /* 324 * Clear the SACK scoreboard, reset FACK estimate. 325 */ 326 tcp_free_sackholes(tp); 327 tp->snd_fack = tp->snd_una; 328 329 /* 330 * Retransmission timer went off. Message has not 331 * been acked within retransmit interval. Back off 332 * to a longer retransmit interval and retransmit one segment. 333 */ 334 335 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { 336 tp->t_rxtshift = TCP_MAXRXTSHIFT; 337 TCP_STATINC(TCP_STAT_TIMEOUTDROP); 338 tp = tcp_drop(tp, tp->t_softerror ? 339 tp->t_softerror : ETIMEDOUT); 340 goto out; 341 } 342 TCP_STATINC(TCP_STAT_REXMTTIMEO); 343 rto = TCP_REXMTVAL(tp); 344 if (rto < tp->t_rttmin) 345 rto = tp->t_rttmin; 346 TCPT_RANGESET(tp->t_rxtcur, rto * tcp_backoff[tp->t_rxtshift], 347 tp->t_rttmin, TCPTV_REXMTMAX); 348 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 349 350 /* 351 * If we are losing and we are trying path MTU discovery, 352 * try turning it off. This will avoid black holes in 353 * the network which suppress or fail to send "packet 354 * too big" ICMP messages. We should ideally do 355 * lots more sophisticated searching to find the right 356 * value here... 357 */ 358 if (tp->t_mtudisc && tp->t_rxtshift > TCP_MAXRXTSHIFT / 6) { 359 TCP_STATINC(TCP_STAT_PMTUBLACKHOLE); 360 361#ifdef INET 362 /* try turning PMTUD off */ 363 if (tp->t_inpcb) 364 tp->t_mtudisc = 0; 365#endif 366#ifdef INET6 367 /* try using IPv6 minimum MTU */ 368 if (tp->t_in6pcb) 369 tp->t_mtudisc = 0; 370#endif 371 372 /* XXX: more sophisticated Black hole recovery code? */ 373 } 374 375 /* 376 * If losing, let the lower level know and try for 377 * a better route. Also, if we backed off this far, 378 * our srtt estimate is probably bogus. Clobber it 379 * so we'll take the next rtt measurement as our srtt; 380 * move the current srtt into rttvar to keep the current 381 * retransmit times until then. 382 */ 383 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { 384#ifdef INET 385 if (tp->t_inpcb) 386 in_losing(tp->t_inpcb); 387#endif 388#ifdef INET6 389 if (tp->t_in6pcb) 390 in6_losing(tp->t_in6pcb); 391#endif 392 /* 393 * This operation is not described in RFC2988. The 394 * point is to keep srtt+4*rttvar constant, so we 395 * should shift right 2 bits to divide by 4, and then 396 * shift right one bit because the storage 397 * representation of rttvar is 1/16s vs 1/32s for 398 * srtt. 399 */ 400 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); 401 tp->t_srtt = 0; 402 } 403 tp->snd_nxt = tp->snd_una; 404 tp->snd_high = tp->snd_max; 405 /* 406 * If timing a segment in this window, stop the timer. 407 */ 408 tp->t_rtttime = 0; 409 /* 410 * Remember if we are retransmitting a SYN, because if 411 * we do, set the initial congestion window must be set 412 * to 1 segment. 413 */ 414 if (tp->t_state == TCPS_SYN_SENT) 415 tp->t_flags |= TF_SYN_REXMT; 416 417 /* 418 * Adjust congestion control parameters. 419 */ 420 tp->t_congctl->slow_retransmit(tp); 421 422 (void) tcp_output(tp); 423 424 out: 425#ifdef TCP_DEBUG 426 if (tp && so->so_options & SO_DEBUG) 427 tcp_trace(TA_USER, ostate, tp, NULL, 428 PRU_SLOWTIMO | (TCPT_REXMT << 8)); 429#endif 430 KERNEL_UNLOCK_ONE(NULL); 431 mutex_exit(softnet_lock); 432} 433 434void 435tcp_timer_persist(void *arg) 436{ 437 struct tcpcb *tp = arg; 438 uint32_t rto; 439#ifdef TCP_DEBUG 440 struct socket *so = NULL; 441 short ostate; 442#endif 443 444 mutex_enter(softnet_lock); 445 if ((tp->t_flags & TF_DEAD) != 0) { 446 mutex_exit(softnet_lock); 447 return; 448 } 449 if (!callout_expired(&tp->t_timer[TCPT_PERSIST])) { 450 mutex_exit(softnet_lock); 451 return; 452 } 453 454 KERNEL_LOCK(1, NULL); 455#ifdef TCP_DEBUG 456#ifdef INET 457 if (tp->t_inpcb) 458 so = tp->t_inpcb->inp_socket; 459#endif 460#ifdef INET6 461 if (tp->t_in6pcb) 462 so = tp->t_in6pcb->in6p_socket; 463#endif 464 465 ostate = tp->t_state; 466#endif /* TCP_DEBUG */ 467 468 /* 469 * Persistance timer into zero window. 470 * Force a byte to be output, if possible. 471 */ 472 473 /* 474 * Hack: if the peer is dead/unreachable, we do not 475 * time out if the window is closed. After a full 476 * backoff, drop the connection if the idle time 477 * (no responses to probes) reaches the maximum 478 * backoff that we would use if retransmitting. 479 */ 480 rto = TCP_REXMTVAL(tp); 481 if (rto < tp->t_rttmin) 482 rto = tp->t_rttmin; 483 if (tp->t_rxtshift == TCP_MAXRXTSHIFT && 484 ((tcp_now - tp->t_rcvtime) >= tcp_maxpersistidle || 485 (tcp_now - tp->t_rcvtime) >= rto * tcp_totbackoff)) { 486 TCP_STATINC(TCP_STAT_PERSISTDROPS); 487 tp = tcp_drop(tp, ETIMEDOUT); 488 goto out; 489 } 490 TCP_STATINC(TCP_STAT_PERSISTTIMEO); 491 tcp_setpersist(tp); 492 tp->t_force = 1; 493 (void) tcp_output(tp); 494 tp->t_force = 0; 495 496 out: 497#ifdef TCP_DEBUG 498 if (tp && so->so_options & SO_DEBUG) 499 tcp_trace(TA_USER, ostate, tp, NULL, 500 PRU_SLOWTIMO | (TCPT_PERSIST << 8)); 501#endif 502 KERNEL_UNLOCK_ONE(NULL); 503 mutex_exit(softnet_lock); 504} 505 506void 507tcp_timer_keep(void *arg) 508{ 509 struct tcpcb *tp = arg; 510 struct socket *so = NULL; /* Quell compiler warning */ 511#ifdef TCP_DEBUG 512 short ostate; 513#endif 514 515 mutex_enter(softnet_lock); 516 if ((tp->t_flags & TF_DEAD) != 0) { 517 mutex_exit(softnet_lock); 518 return; 519 } 520 if (!callout_expired(&tp->t_timer[TCPT_KEEP])) { 521 mutex_exit(softnet_lock); 522 return; 523 } 524 525 KERNEL_LOCK(1, NULL); 526 527#ifdef TCP_DEBUG 528 ostate = tp->t_state; 529#endif /* TCP_DEBUG */ 530 531 /* 532 * Keep-alive timer went off; send something 533 * or drop connection if idle for too long. 534 */ 535 536 TCP_STATINC(TCP_STAT_KEEPTIMEO); 537 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 538 goto dropit; 539#ifdef INET 540 if (tp->t_inpcb) 541 so = tp->t_inpcb->inp_socket; 542#endif 543#ifdef INET6 544 if (tp->t_in6pcb) 545 so = tp->t_in6pcb->in6p_socket; 546#endif 547 KASSERT(so != NULL); 548 if (so->so_options & SO_KEEPALIVE && 549 tp->t_state <= TCPS_CLOSE_WAIT) { 550 if ((tp->t_maxidle > 0) && 551 ((tcp_now - tp->t_rcvtime) >= 552 tp->t_keepidle + tp->t_maxidle)) 553 goto dropit; 554 /* 555 * Send a packet designed to force a response 556 * if the peer is up and reachable: 557 * either an ACK if the connection is still alive, 558 * or an RST if the peer has closed the connection 559 * due to timeout or reboot. 560 * Using sequence number tp->snd_una-1 561 * causes the transmitted zero-length segment 562 * to lie outside the receive window; 563 * by the protocol spec, this requires the 564 * correspondent TCP to respond. 565 */ 566 TCP_STATINC(TCP_STAT_KEEPPROBE); 567 if (tcp_compat_42) { 568 /* 569 * The keepalive packet must have nonzero 570 * length to get a 4.2 host to respond. 571 */ 572 (void)tcp_respond(tp, tp->t_template, 573 NULL, NULL, tp->rcv_nxt - 1, 574 tp->snd_una - 1, 0); 575 } else { 576 (void)tcp_respond(tp, tp->t_template, 577 NULL, NULL, tp->rcv_nxt, 578 tp->snd_una - 1, 0); 579 } 580 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepintvl); 581 } else 582 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle); 583 584#ifdef TCP_DEBUG 585 if (tp && so->so_options & SO_DEBUG) 586 tcp_trace(TA_USER, ostate, tp, NULL, 587 PRU_SLOWTIMO | (TCPT_KEEP << 8)); 588#endif 589 KERNEL_UNLOCK_ONE(NULL); 590 mutex_exit(softnet_lock); 591 return; 592 593 dropit: 594 TCP_STATINC(TCP_STAT_KEEPDROPS); 595 (void) tcp_drop(tp, ETIMEDOUT); 596 KERNEL_UNLOCK_ONE(NULL); 597 mutex_exit(softnet_lock); 598} 599 600void 601tcp_timer_2msl(void *arg) 602{ 603 struct tcpcb *tp = arg; 604#ifdef TCP_DEBUG 605 struct socket *so = NULL; 606 short ostate; 607#endif 608 609 mutex_enter(softnet_lock); 610 if ((tp->t_flags & TF_DEAD) != 0) { 611 mutex_exit(softnet_lock); 612 return; 613 } 614 if (!callout_expired(&tp->t_timer[TCPT_2MSL])) { 615 mutex_exit(softnet_lock); 616 return; 617 } 618 619 /* 620 * 2 MSL timeout went off, clear the SACK scoreboard, reset 621 * the FACK estimate. 622 */ 623 KERNEL_LOCK(1, NULL); 624 tcp_free_sackholes(tp); 625 tp->snd_fack = tp->snd_una; 626 627#ifdef TCP_DEBUG 628#ifdef INET 629 if (tp->t_inpcb) 630 so = tp->t_inpcb->inp_socket; 631#endif 632#ifdef INET6 633 if (tp->t_in6pcb) 634 so = tp->t_in6pcb->in6p_socket; 635#endif 636 637 ostate = tp->t_state; 638#endif /* TCP_DEBUG */ 639 640 /* 641 * 2 MSL timeout in shutdown went off. If we're closed but 642 * still waiting for peer to close and connection has been idle 643 * too long, or if 2MSL time is up from TIME_WAIT, delete connection 644 * control block. Otherwise, check again in a bit. 645 */ 646 if (tp->t_state != TCPS_TIME_WAIT && 647 ((tp->t_maxidle == 0) || 648 ((tcp_now - tp->t_rcvtime) <= tp->t_maxidle))) 649 TCP_TIMER_ARM(tp, TCPT_2MSL, tp->t_keepintvl); 650 else 651 tp = tcp_close(tp); 652 653#ifdef TCP_DEBUG 654 if (tp && so->so_options & SO_DEBUG) 655 tcp_trace(TA_USER, ostate, tp, NULL, 656 PRU_SLOWTIMO | (TCPT_2MSL << 8)); 657#endif 658 mutex_exit(softnet_lock); 659 KERNEL_UNLOCK_ONE(NULL); 660} 661