1/* $NetBSD: tcp_timer.c,v 1.99 2022/11/04 09:00:58 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 1.99 2022/11/04 09:00:58 ozaki-r Exp $"); 97 98#ifdef _KERNEL_OPT 99#include "opt_inet.h" 100#include "opt_tcp_debug.h" 101#include "opt_net_mpsafe.h" 102#endif 103 104#include <sys/param.h> 105#include <sys/systm.h> 106#include <sys/mbuf.h> 107#include <sys/socket.h> 108#include <sys/socketvar.h> 109#include <sys/protosw.h> 110#include <sys/errno.h> 111#include <sys/kernel.h> 112#include <sys/callout.h> 113#include <sys/workqueue.h> 114#include <sys/cprng.h> 115 116#include <net/if.h> 117 118#include <netinet/in.h> 119#include <netinet/in_systm.h> 120#include <netinet/ip.h> 121#include <netinet/in_pcb.h> 122#include <netinet/ip_var.h> 123#include <netinet/ip_icmp.h> 124 125#ifdef INET6 126#include <netinet/ip6.h> 127#include <netinet6/in6_pcb.h> 128#endif 129 130#include <netinet/tcp.h> 131#include <netinet/tcp_fsm.h> 132#include <netinet/tcp_seq.h> 133#include <netinet/tcp_timer.h> 134#include <netinet/tcp_var.h> 135#include <netinet/tcp_private.h> 136#include <netinet/tcp_congctl.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 152static callout_t tcp_slowtimo_ch; 153#ifdef NET_MPSAFE 154static struct workqueue *tcp_slowtimo_wq; 155static struct work tcp_slowtimo_wk; 156#endif 157 158static void tcp_slowtimo_work(struct work *, void *); 159static void tcp_slowtimo(void *); 160 161/* 162 * Time to delay the ACK. This is initialized in tcp_init(), unless 163 * its patched. 164 */ 165int tcp_delack_ticks = 0; 166 167void tcp_timer_rexmt(void *); 168void tcp_timer_persist(void *); 169void tcp_timer_keep(void *); 170void tcp_timer_2msl(void *); 171 172const tcp_timer_func_t tcp_timer_funcs[TCPT_NTIMERS] = { 173 tcp_timer_rexmt, 174 tcp_timer_persist, 175 tcp_timer_keep, 176 tcp_timer_2msl, 177}; 178 179/* 180 * Timer state initialization, called from tcp_init(). 181 */ 182void 183tcp_timer_init(void) 184{ 185 186 if (tcp_keepinit == 0) 187 tcp_keepinit = TCPTV_KEEP_INIT; 188 189 if (tcp_keepidle == 0) 190 tcp_keepidle = TCPTV_KEEP_IDLE; 191 192 if (tcp_keepintvl == 0) 193 tcp_keepintvl = TCPTV_KEEPINTVL; 194 195 if (tcp_keepcnt == 0) 196 tcp_keepcnt = TCPTV_KEEPCNT; 197 198 if (tcp_maxpersistidle == 0) 199 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 200 201 if (tcp_delack_ticks == 0) 202 tcp_delack_ticks = TCP_DELACK_TICKS; 203} 204 205void 206tcp_slowtimo_init(void) 207{ 208#ifdef NET_MPSAFE 209 int error; 210 211 error = workqueue_create(&tcp_slowtimo_wq, "tcp_slowtimo", 212 tcp_slowtimo_work, NULL, PRI_SOFTNET, IPL_SOFTNET, WQ_MPSAFE); 213 if (error != 0) 214 panic("%s: workqueue_create failed (%d)\n", __func__, error); 215#endif 216 callout_init(&tcp_slowtimo_ch, CALLOUT_MPSAFE); 217 callout_reset(&tcp_slowtimo_ch, 1, tcp_slowtimo, NULL); 218} 219 220/* 221 * Callout to process delayed ACKs for a TCPCB. 222 */ 223void 224tcp_delack(void *arg) 225{ 226 struct tcpcb *tp = arg; 227 228 /* 229 * If tcp_output() wasn't able to transmit the ACK 230 * for whatever reason, it will restart the delayed 231 * ACK callout. 232 */ 233 234 mutex_enter(softnet_lock); 235 if ((tp->t_flags & (TF_DEAD | TF_DELACK)) != TF_DELACK) { 236 mutex_exit(softnet_lock); 237 return; 238 } 239 if (!callout_expired(&tp->t_delack_ch)) { 240 mutex_exit(softnet_lock); 241 return; 242 } 243 244 tp->t_flags |= TF_ACKNOW; 245 KERNEL_LOCK(1, NULL); 246 (void) tcp_output(tp); 247 KERNEL_UNLOCK_ONE(NULL); 248 mutex_exit(softnet_lock); 249} 250 251/* 252 * Tcp protocol timeout routine called every 500 ms. 253 * Updates the timers in all active tcb's and 254 * causes finite state machine actions if timers expire. 255 */ 256static void 257tcp_slowtimo_work(struct work *wk, void *arg) 258{ 259 260 mutex_enter(softnet_lock); 261 tcp_iss_seq += TCP_ISSINCR + (TCP_ISS_RANDOM_MASK & cprng_fast32()); 262 tcp_now++; /* for timestamps */ 263 mutex_exit(softnet_lock); 264 265 callout_schedule(&tcp_slowtimo_ch, hz / PR_SLOWHZ); 266} 267 268static void 269tcp_slowtimo(void *arg) 270{ 271 272#ifdef NET_MPSAFE 273 workqueue_enqueue(tcp_slowtimo_wq, &tcp_slowtimo_wk, NULL); 274#else 275 tcp_slowtimo_work(NULL, NULL); 276#endif 277} 278 279/* 280 * Cancel all timers for TCP tp. 281 */ 282void 283tcp_canceltimers(struct tcpcb *tp) 284{ 285 int i; 286 287 for (i = 0; i < TCPT_NTIMERS; i++) 288 TCP_TIMER_DISARM(tp, i); 289} 290 291const int tcp_backoff[TCP_MAXRXTSHIFT + 1] = 292 { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 }; 293 294const int tcp_totbackoff = 511; /* sum of tcp_backoff[] */ 295 296/* 297 * TCP timer processing. 298 */ 299 300void 301tcp_timer_rexmt(void *arg) 302{ 303 struct tcpcb *tp = arg; 304 uint32_t rto; 305#ifdef TCP_DEBUG 306 struct socket *so = NULL; 307 short ostate; 308#endif 309 310 mutex_enter(softnet_lock); 311 if ((tp->t_flags & TF_DEAD) != 0) { 312 mutex_exit(softnet_lock); 313 return; 314 } 315 if (!callout_expired(&tp->t_timer[TCPT_REXMT])) { 316 mutex_exit(softnet_lock); 317 return; 318 } 319 320 KERNEL_LOCK(1, NULL); 321 if ((tp->t_flags & TF_PMTUD_PEND) && tp->t_inpcb && 322 SEQ_GEQ(tp->t_pmtud_th_seq, tp->snd_una) && 323 SEQ_LT(tp->t_pmtud_th_seq, (int)(tp->snd_una + tp->t_ourmss))) { 324 extern struct sockaddr_in icmpsrc; 325 struct icmp icmp; 326 327 tp->t_flags &= ~TF_PMTUD_PEND; 328 329 /* XXX create fake icmp message with relevant entries */ 330 icmp.icmp_nextmtu = tp->t_pmtud_nextmtu; 331 icmp.icmp_ip.ip_len = tp->t_pmtud_ip_len; 332 icmp.icmp_ip.ip_hl = tp->t_pmtud_ip_hl; 333 icmpsrc.sin_addr = in4p_faddr(tp->t_inpcb); 334 icmp_mtudisc(&icmp, icmpsrc.sin_addr); 335 336 /* 337 * Notify all connections to the same peer about 338 * new mss and trigger retransmit. 339 */ 340 inpcb_notifyall(&tcbtable, icmpsrc.sin_addr, EMSGSIZE, 341 tcp_mtudisc); 342 KERNEL_UNLOCK_ONE(NULL); 343 mutex_exit(softnet_lock); 344 return; 345 } 346#ifdef TCP_DEBUG 347 so = tp->t_inpcb->inp_socket; 348 ostate = tp->t_state; 349#endif /* TCP_DEBUG */ 350 351 /* 352 * Clear the SACK scoreboard, reset FACK estimate. 353 */ 354 tcp_free_sackholes(tp); 355 tp->snd_fack = tp->snd_una; 356 357 /* 358 * Retransmission timer went off. Message has not 359 * been acked within retransmit interval. Back off 360 * to a longer retransmit interval and retransmit one segment. 361 */ 362 363 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { 364 tp->t_rxtshift = TCP_MAXRXTSHIFT; 365 TCP_STATINC(TCP_STAT_TIMEOUTDROP); 366 tp = tcp_drop(tp, tp->t_softerror ? 367 tp->t_softerror : ETIMEDOUT); 368 goto out; 369 } 370 TCP_STATINC(TCP_STAT_REXMTTIMEO); 371 rto = TCP_REXMTVAL(tp); 372 if (rto < tp->t_rttmin) 373 rto = tp->t_rttmin; 374 TCPT_RANGESET(tp->t_rxtcur, rto * tcp_backoff[tp->t_rxtshift], 375 tp->t_rttmin, TCPTV_REXMTMAX); 376 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 377 378 /* 379 * If we are losing and we are trying path MTU discovery, 380 * try turning it off. This will avoid black holes in 381 * the network which suppress or fail to send "packet 382 * too big" ICMP messages. We should ideally do 383 * lots more sophisticated searching to find the right 384 * value here... 385 */ 386 if (tp->t_mtudisc && tp->t_rxtshift > TCP_MAXRXTSHIFT / 6) { 387 TCP_STATINC(TCP_STAT_PMTUBLACKHOLE); 388 389 /* try turning PMTUD off or try using IPv6 minimum MTU */ 390 tp->t_mtudisc = 0; 391 392 /* XXX: more sophisticated Black hole recovery code? */ 393 } 394 395 /* 396 * If losing, let the lower level know and try for 397 * a better route. Also, if we backed off this far, 398 * our srtt estimate is probably bogus. Clobber it 399 * so we'll take the next rtt measurement as our srtt; 400 * move the current srtt into rttvar to keep the current 401 * retransmit times until then. 402 */ 403 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { 404 inpcb_losing(tp->t_inpcb); 405 /* 406 * This operation is not described in RFC2988. The 407 * point is to keep srtt+4*rttvar constant, so we 408 * should shift right 2 bits to divide by 4, and then 409 * shift right one bit because the storage 410 * representation of rttvar is 1/16s vs 1/32s for 411 * srtt. 412 */ 413 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); 414 tp->t_srtt = 0; 415 } 416 tp->snd_nxt = tp->snd_una; 417 tp->snd_high = tp->snd_max; 418 /* 419 * If timing a segment in this window, stop the timer. 420 */ 421 tp->t_rtttime = 0; 422 /* 423 * Remember if we are retransmitting a SYN, because if 424 * we do, set the initial congestion window must be set 425 * to 1 segment. 426 */ 427 if (tp->t_state == TCPS_SYN_SENT) 428 tp->t_flags |= TF_SYN_REXMT; 429 430 /* 431 * Adjust congestion control parameters. 432 */ 433 tp->t_congctl->slow_retransmit(tp); 434 435 (void) tcp_output(tp); 436 437 out: 438#ifdef TCP_DEBUG 439 if (tp && so->so_options & SO_DEBUG) 440 tcp_trace(TA_USER, ostate, tp, NULL, 441 PRU_SLOWTIMO | (TCPT_REXMT << 8)); 442#endif 443 KERNEL_UNLOCK_ONE(NULL); 444 mutex_exit(softnet_lock); 445} 446 447void 448tcp_timer_persist(void *arg) 449{ 450 struct tcpcb *tp = arg; 451 uint32_t rto; 452#ifdef TCP_DEBUG 453 struct socket *so = NULL; 454 short ostate; 455#endif 456 457 mutex_enter(softnet_lock); 458 if ((tp->t_flags & TF_DEAD) != 0) { 459 mutex_exit(softnet_lock); 460 return; 461 } 462 if (!callout_expired(&tp->t_timer[TCPT_PERSIST])) { 463 mutex_exit(softnet_lock); 464 return; 465 } 466 467 KERNEL_LOCK(1, NULL); 468#ifdef TCP_DEBUG 469 so = tp->t_inpcb->inp_socket; 470 ostate = tp->t_state; 471#endif /* TCP_DEBUG */ 472 473 /* 474 * Persistance timer into zero window. 475 * Force a byte to be output, if possible. 476 */ 477 478 /* 479 * Hack: if the peer is dead/unreachable, we do not 480 * time out if the window is closed. After a full 481 * backoff, drop the connection if the idle time 482 * (no responses to probes) reaches the maximum 483 * backoff that we would use if retransmitting. 484 */ 485 rto = TCP_REXMTVAL(tp); 486 if (rto < tp->t_rttmin) 487 rto = tp->t_rttmin; 488 if (tp->t_rxtshift == TCP_MAXRXTSHIFT && 489 ((tcp_now - tp->t_rcvtime) >= tcp_maxpersistidle || 490 (tcp_now - tp->t_rcvtime) >= rto * tcp_totbackoff)) { 491 TCP_STATINC(TCP_STAT_PERSISTDROPS); 492 tp = tcp_drop(tp, ETIMEDOUT); 493 goto out; 494 } 495 TCP_STATINC(TCP_STAT_PERSISTTIMEO); 496 tcp_setpersist(tp); 497 tp->t_force = 1; 498 (void) tcp_output(tp); 499 tp->t_force = 0; 500 501 out: 502#ifdef TCP_DEBUG 503 if (tp && so->so_options & SO_DEBUG) 504 tcp_trace(TA_USER, ostate, tp, NULL, 505 PRU_SLOWTIMO | (TCPT_PERSIST << 8)); 506#endif 507 KERNEL_UNLOCK_ONE(NULL); 508 mutex_exit(softnet_lock); 509} 510 511void 512tcp_timer_keep(void *arg) 513{ 514 struct tcpcb *tp = arg; 515 struct socket *so = NULL; /* Quell compiler warning */ 516#ifdef TCP_DEBUG 517 short ostate; 518#endif 519 520 mutex_enter(softnet_lock); 521 if ((tp->t_flags & TF_DEAD) != 0) { 522 mutex_exit(softnet_lock); 523 return; 524 } 525 if (!callout_expired(&tp->t_timer[TCPT_KEEP])) { 526 mutex_exit(softnet_lock); 527 return; 528 } 529 530 KERNEL_LOCK(1, NULL); 531 532#ifdef TCP_DEBUG 533 ostate = tp->t_state; 534#endif /* TCP_DEBUG */ 535 536 /* 537 * Keep-alive timer went off; send something 538 * or drop connection if idle for too long. 539 */ 540 541 TCP_STATINC(TCP_STAT_KEEPTIMEO); 542 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 543 goto dropit; 544 so = tp->t_inpcb->inp_socket; 545 KASSERT(so != NULL); 546 if (so->so_options & SO_KEEPALIVE && 547 tp->t_state <= TCPS_CLOSE_WAIT) { 548 if ((tp->t_maxidle > 0) && 549 ((tcp_now - tp->t_rcvtime) >= 550 tp->t_keepidle + tp->t_maxidle)) 551 goto dropit; 552 /* 553 * Send a packet designed to force a response 554 * if the peer is up and reachable: 555 * either an ACK if the connection is still alive, 556 * or an RST if the peer has closed the connection 557 * due to timeout or reboot. 558 * Using sequence number tp->snd_una-1 559 * causes the transmitted zero-length segment 560 * to lie outside the receive window; 561 * by the protocol spec, this requires the 562 * correspondent TCP to respond. 563 */ 564 TCP_STATINC(TCP_STAT_KEEPPROBE); 565 566 (void)tcp_respond(tp, tp->t_template, 567 NULL, NULL, tp->rcv_nxt, 568 tp->snd_una - 1, 0); 569 570 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepintvl); 571 } else 572 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle); 573 574#ifdef TCP_DEBUG 575 if (tp && so->so_options & SO_DEBUG) 576 tcp_trace(TA_USER, ostate, tp, NULL, 577 PRU_SLOWTIMO | (TCPT_KEEP << 8)); 578#endif 579 KERNEL_UNLOCK_ONE(NULL); 580 mutex_exit(softnet_lock); 581 return; 582 583 dropit: 584 TCP_STATINC(TCP_STAT_KEEPDROPS); 585 (void) tcp_drop(tp, ETIMEDOUT); 586 KERNEL_UNLOCK_ONE(NULL); 587 mutex_exit(softnet_lock); 588} 589 590void 591tcp_timer_2msl(void *arg) 592{ 593 struct tcpcb *tp = arg; 594#ifdef TCP_DEBUG 595 struct socket *so = NULL; 596 short ostate; 597#endif 598 599 mutex_enter(softnet_lock); 600 if ((tp->t_flags & TF_DEAD) != 0) { 601 mutex_exit(softnet_lock); 602 return; 603 } 604 if (!callout_expired(&tp->t_timer[TCPT_2MSL])) { 605 mutex_exit(softnet_lock); 606 return; 607 } 608 609 /* 610 * 2 MSL timeout went off, clear the SACK scoreboard, reset 611 * the FACK estimate. 612 */ 613 KERNEL_LOCK(1, NULL); 614 tcp_free_sackholes(tp); 615 tp->snd_fack = tp->snd_una; 616 617#ifdef TCP_DEBUG 618 so = tp->t_inpcb->inp_socket; 619 ostate = tp->t_state; 620#endif /* TCP_DEBUG */ 621 622 /* 623 * 2 MSL timeout in shutdown went off. If we're closed but 624 * still waiting for peer to close and connection has been idle 625 * too long, or if 2MSL time is up from TIME_WAIT, delete connection 626 * control block. Otherwise, check again in a bit. 627 */ 628 if (tp->t_state != TCPS_TIME_WAIT && 629 ((tp->t_maxidle == 0) || 630 ((tcp_now - tp->t_rcvtime) <= tp->t_maxidle))) 631 TCP_TIMER_ARM(tp, TCPT_2MSL, tp->t_keepintvl); 632 else 633 tp = tcp_close(tp); 634 635#ifdef TCP_DEBUG 636 if (tp && so->so_options & SO_DEBUG) 637 tcp_trace(TA_USER, ostate, tp, NULL, 638 PRU_SLOWTIMO | (TCPT_2MSL << 8)); 639#endif 640 KERNEL_UNLOCK_ONE(NULL); 641 mutex_exit(softnet_lock); 642} 643