tcp_timer.c revision 1.82
1 /* $NetBSD: tcp_timer.c,v 1.82 2008/10/10 10:21:05 ad 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 1.82 2008/10/10 10:21:05 ad Exp $"); 97 98 #include "opt_inet.h" 99 #include "opt_tcp_debug.h" 100 101 #include <sys/param.h> 102 #include <sys/systm.h> 103 #include <sys/malloc.h> 104 #include <sys/mbuf.h> 105 #include <sys/socket.h> 106 #include <sys/socketvar.h> 107 #include <sys/protosw.h> 108 #include <sys/errno.h> 109 #include <sys/kernel.h> 110 111 #include <net/if.h> 112 #include <net/route.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 */ 145 u_int tcp_keepinit = 0; 146 u_int tcp_keepidle = 0; 147 u_int tcp_keepintvl = 0; 148 u_int tcp_keepcnt = 0; /* max idle probes */ 149 150 int 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 */ 156 int tcp_delack_ticks = 0; 157 158 void tcp_timer_rexmt(void *); 159 void tcp_timer_persist(void *); 160 void tcp_timer_keep(void *); 161 void tcp_timer_2msl(void *); 162 163 const 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 */ 173 void 174 tcp_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 */ 199 void 200 tcp_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 } 215 216 tp->t_flags |= TF_ACKNOW; 217 KERNEL_LOCK(1, NULL); 218 (void) tcp_output(tp); 219 KERNEL_UNLOCK_ONE(NULL); 220 mutex_exit(softnet_lock); 221 } 222 223 /* 224 * Tcp protocol timeout routine called every 500 ms. 225 * Updates the timers in all active tcb's and 226 * causes finite state machine actions if timers expire. 227 */ 228 void 229 tcp_slowtimo(void) 230 { 231 232 mutex_enter(softnet_lock); 233 tcp_iss_seq += TCP_ISSINCR; /* increment iss */ 234 tcp_now++; /* for timestamps */ 235 mutex_exit(softnet_lock); 236 } 237 238 /* 239 * Cancel all timers for TCP tp. 240 */ 241 void 242 tcp_canceltimers(struct tcpcb *tp) 243 { 244 int i; 245 246 for (i = 0; i < TCPT_NTIMERS; i++) 247 TCP_TIMER_DISARM(tp, i); 248 } 249 250 const int tcp_backoff[TCP_MAXRXTSHIFT + 1] = 251 { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 }; 252 253 const int tcp_totbackoff = 511; /* sum of tcp_backoff[] */ 254 255 /* 256 * TCP timer processing. 257 */ 258 259 void 260 tcp_timer_rexmt(void *arg) 261 { 262 struct tcpcb *tp = arg; 263 uint32_t rto; 264 #ifdef TCP_DEBUG 265 struct socket *so = NULL; 266 short ostate; 267 #endif 268 269 mutex_enter(softnet_lock); 270 if ((tp->t_flags & TF_DEAD) != 0) { 271 mutex_exit(softnet_lock); 272 return; 273 } 274 275 KERNEL_LOCK(1, NULL); 276 if ((tp->t_flags & TF_PMTUD_PEND) && tp->t_inpcb && 277 SEQ_GEQ(tp->t_pmtud_th_seq, tp->snd_una) && 278 SEQ_LT(tp->t_pmtud_th_seq, (int)(tp->snd_una + tp->t_ourmss))) { 279 extern struct sockaddr_in icmpsrc; 280 struct icmp icmp; 281 282 tp->t_flags &= ~TF_PMTUD_PEND; 283 284 /* XXX create fake icmp message with relevant entries */ 285 icmp.icmp_nextmtu = tp->t_pmtud_nextmtu; 286 icmp.icmp_ip.ip_len = tp->t_pmtud_ip_len; 287 icmp.icmp_ip.ip_hl = tp->t_pmtud_ip_hl; 288 icmpsrc.sin_addr = tp->t_inpcb->inp_faddr; 289 icmp_mtudisc(&icmp, icmpsrc.sin_addr); 290 291 /* 292 * Notify all connections to the same peer about 293 * new mss and trigger retransmit. 294 */ 295 in_pcbnotifyall(&tcbtable, icmpsrc.sin_addr, EMSGSIZE, 296 tcp_mtudisc); 297 KERNEL_UNLOCK_ONE(NULL); 298 mutex_exit(softnet_lock); 299 return; 300 } 301 #ifdef TCP_DEBUG 302 #ifdef INET 303 if (tp->t_inpcb) 304 so = tp->t_inpcb->inp_socket; 305 #endif 306 #ifdef INET6 307 if (tp->t_in6pcb) 308 so = tp->t_in6pcb->in6p_socket; 309 #endif 310 ostate = tp->t_state; 311 #endif /* TCP_DEBUG */ 312 313 /* 314 * Clear the SACK scoreboard, reset FACK estimate. 315 */ 316 tcp_free_sackholes(tp); 317 tp->snd_fack = tp->snd_una; 318 319 /* 320 * Retransmission timer went off. Message has not 321 * been acked within retransmit interval. Back off 322 * to a longer retransmit interval and retransmit one segment. 323 */ 324 325 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { 326 tp->t_rxtshift = TCP_MAXRXTSHIFT; 327 TCP_STATINC(TCP_STAT_TIMEOUTDROP); 328 tp = tcp_drop(tp, tp->t_softerror ? 329 tp->t_softerror : ETIMEDOUT); 330 goto out; 331 } 332 TCP_STATINC(TCP_STAT_REXMTTIMEO); 333 rto = TCP_REXMTVAL(tp); 334 if (rto < tp->t_rttmin) 335 rto = tp->t_rttmin; 336 TCPT_RANGESET(tp->t_rxtcur, rto * tcp_backoff[tp->t_rxtshift], 337 tp->t_rttmin, TCPTV_REXMTMAX); 338 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 339 340 /* 341 * If we are losing and we are trying path MTU discovery, 342 * try turning it off. This will avoid black holes in 343 * the network which suppress or fail to send "packet 344 * too big" ICMP messages. We should ideally do 345 * lots more sophisticated searching to find the right 346 * value here... 347 */ 348 if (tp->t_mtudisc && tp->t_rxtshift > TCP_MAXRXTSHIFT / 6) { 349 TCP_STATINC(TCP_STAT_PMTUBLACKHOLE); 350 351 #ifdef INET 352 /* try turning PMTUD off */ 353 if (tp->t_inpcb) 354 tp->t_mtudisc = 0; 355 #endif 356 #ifdef INET6 357 /* try using IPv6 minimum MTU */ 358 if (tp->t_in6pcb) 359 tp->t_mtudisc = 0; 360 #endif 361 362 /* XXX: more sophisticated Black hole recovery code? */ 363 } 364 365 /* 366 * If losing, let the lower level know and try for 367 * a better route. Also, if we backed off this far, 368 * our srtt estimate is probably bogus. Clobber it 369 * so we'll take the next rtt measurement as our srtt; 370 * move the current srtt into rttvar to keep the current 371 * retransmit times until then. 372 */ 373 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { 374 #ifdef INET 375 if (tp->t_inpcb) 376 in_losing(tp->t_inpcb); 377 #endif 378 #ifdef INET6 379 if (tp->t_in6pcb) 380 in6_losing(tp->t_in6pcb); 381 #endif 382 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); 383 tp->t_srtt = 0; 384 } 385 tp->snd_nxt = tp->snd_una; 386 tp->snd_high = tp->snd_max; 387 /* 388 * If timing a segment in this window, stop the timer. 389 */ 390 tp->t_rtttime = 0; 391 /* 392 * Remember if we are retransmitting a SYN, because if 393 * we do, set the initial congestion window must be set 394 * to 1 segment. 395 */ 396 if (tp->t_state == TCPS_SYN_SENT) 397 tp->t_flags |= TF_SYN_REXMT; 398 399 /* 400 * Adjust congestion control parameters. 401 */ 402 tp->t_congctl->slow_retransmit(tp); 403 404 (void) tcp_output(tp); 405 406 out: 407 #ifdef TCP_DEBUG 408 if (tp && so->so_options & SO_DEBUG) 409 tcp_trace(TA_USER, ostate, tp, NULL, 410 PRU_SLOWTIMO | (TCPT_REXMT << 8)); 411 #endif 412 KERNEL_UNLOCK_ONE(NULL); 413 mutex_exit(softnet_lock); 414 } 415 416 void 417 tcp_timer_persist(void *arg) 418 { 419 struct tcpcb *tp = arg; 420 uint32_t rto; 421 #ifdef TCP_DEBUG 422 struct socket *so = NULL; 423 short ostate; 424 #endif 425 426 mutex_enter(softnet_lock); 427 if ((tp->t_flags & TF_DEAD) != 0) { 428 mutex_exit(softnet_lock); 429 return; 430 } 431 432 KERNEL_LOCK(1, NULL); 433 #ifdef TCP_DEBUG 434 #ifdef INET 435 if (tp->t_inpcb) 436 so = tp->t_inpcb->inp_socket; 437 #endif 438 #ifdef INET6 439 if (tp->t_in6pcb) 440 so = tp->t_in6pcb->in6p_socket; 441 #endif 442 443 ostate = tp->t_state; 444 #endif /* TCP_DEBUG */ 445 446 /* 447 * Persistance timer into zero window. 448 * Force a byte to be output, if possible. 449 */ 450 451 /* 452 * Hack: if the peer is dead/unreachable, we do not 453 * time out if the window is closed. After a full 454 * backoff, drop the connection if the idle time 455 * (no responses to probes) reaches the maximum 456 * backoff that we would use if retransmitting. 457 */ 458 rto = TCP_REXMTVAL(tp); 459 if (rto < tp->t_rttmin) 460 rto = tp->t_rttmin; 461 if (tp->t_rxtshift == TCP_MAXRXTSHIFT && 462 ((tcp_now - tp->t_rcvtime) >= tcp_maxpersistidle || 463 (tcp_now - tp->t_rcvtime) >= rto * tcp_totbackoff)) { 464 TCP_STATINC(TCP_STAT_PERSISTDROPS); 465 tp = tcp_drop(tp, ETIMEDOUT); 466 goto out; 467 } 468 TCP_STATINC(TCP_STAT_PERSISTTIMEO); 469 tcp_setpersist(tp); 470 tp->t_force = 1; 471 (void) tcp_output(tp); 472 tp->t_force = 0; 473 474 out: 475 #ifdef TCP_DEBUG 476 if (tp && so->so_options & SO_DEBUG) 477 tcp_trace(TA_USER, ostate, tp, NULL, 478 PRU_SLOWTIMO | (TCPT_PERSIST << 8)); 479 #endif 480 KERNEL_UNLOCK_ONE(NULL); 481 mutex_exit(softnet_lock); 482 } 483 484 void 485 tcp_timer_keep(void *arg) 486 { 487 struct tcpcb *tp = arg; 488 struct socket *so = NULL; /* Quell compiler warning */ 489 #ifdef TCP_DEBUG 490 short ostate; 491 #endif 492 493 mutex_enter(softnet_lock); 494 if ((tp->t_flags & TF_DEAD) != 0) { 495 mutex_exit(softnet_lock); 496 return; 497 } 498 499 KERNEL_LOCK(1, NULL); 500 501 #ifdef TCP_DEBUG 502 ostate = tp->t_state; 503 #endif /* TCP_DEBUG */ 504 505 /* 506 * Keep-alive timer went off; send something 507 * or drop connection if idle for too long. 508 */ 509 510 TCP_STATINC(TCP_STAT_KEEPTIMEO); 511 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 512 goto dropit; 513 #ifdef INET 514 if (tp->t_inpcb) 515 so = tp->t_inpcb->inp_socket; 516 #endif 517 #ifdef INET6 518 if (tp->t_in6pcb) 519 so = tp->t_in6pcb->in6p_socket; 520 #endif 521 KASSERT(so != NULL); 522 if (so->so_options & SO_KEEPALIVE && 523 tp->t_state <= TCPS_CLOSE_WAIT) { 524 if ((tp->t_maxidle > 0) && 525 ((tcp_now - tp->t_rcvtime) >= 526 tp->t_keepidle + tp->t_maxidle)) 527 goto dropit; 528 /* 529 * Send a packet designed to force a response 530 * if the peer is up and reachable: 531 * either an ACK if the connection is still alive, 532 * or an RST if the peer has closed the connection 533 * due to timeout or reboot. 534 * Using sequence number tp->snd_una-1 535 * causes the transmitted zero-length segment 536 * to lie outside the receive window; 537 * by the protocol spec, this requires the 538 * correspondent TCP to respond. 539 */ 540 TCP_STATINC(TCP_STAT_KEEPPROBE); 541 if (tcp_compat_42) { 542 /* 543 * The keepalive packet must have nonzero 544 * length to get a 4.2 host to respond. 545 */ 546 (void)tcp_respond(tp, tp->t_template, 547 (struct mbuf *)NULL, NULL, tp->rcv_nxt - 1, 548 tp->snd_una - 1, 0); 549 } else { 550 (void)tcp_respond(tp, tp->t_template, 551 (struct mbuf *)NULL, NULL, tp->rcv_nxt, 552 tp->snd_una - 1, 0); 553 } 554 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepintvl); 555 } else 556 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle); 557 558 #ifdef TCP_DEBUG 559 if (tp && so->so_options & SO_DEBUG) 560 tcp_trace(TA_USER, ostate, tp, NULL, 561 PRU_SLOWTIMO | (TCPT_KEEP << 8)); 562 #endif 563 KERNEL_UNLOCK_ONE(NULL); 564 mutex_exit(softnet_lock); 565 return; 566 567 dropit: 568 TCP_STATINC(TCP_STAT_KEEPDROPS); 569 (void) tcp_drop(tp, ETIMEDOUT); 570 KERNEL_UNLOCK_ONE(NULL); 571 mutex_exit(softnet_lock); 572 } 573 574 void 575 tcp_timer_2msl(void *arg) 576 { 577 struct tcpcb *tp = arg; 578 #ifdef TCP_DEBUG 579 struct socket *so = NULL; 580 short ostate; 581 #endif 582 583 mutex_enter(softnet_lock); 584 if ((tp->t_flags & TF_DEAD) != 0) { 585 mutex_exit(softnet_lock); 586 return; 587 } 588 589 /* 590 * 2 MSL timeout went off, clear the SACK scoreboard, reset 591 * the FACK estimate. 592 */ 593 KERNEL_LOCK(1, NULL); 594 tcp_free_sackholes(tp); 595 tp->snd_fack = tp->snd_una; 596 597 #ifdef TCP_DEBUG 598 #ifdef INET 599 if (tp->t_inpcb) 600 so = tp->t_inpcb->inp_socket; 601 #endif 602 #ifdef INET6 603 if (tp->t_in6pcb) 604 so = tp->t_in6pcb->in6p_socket; 605 #endif 606 607 ostate = tp->t_state; 608 #endif /* TCP_DEBUG */ 609 610 /* 611 * 2 MSL timeout in shutdown went off. If we're closed but 612 * still waiting for peer to close and connection has been idle 613 * too long, or if 2MSL time is up from TIME_WAIT, delete connection 614 * control block. Otherwise, check again in a bit. 615 */ 616 if (tp->t_state != TCPS_TIME_WAIT && 617 ((tp->t_maxidle == 0) || 618 ((tcp_now - tp->t_rcvtime) <= tp->t_maxidle))) 619 TCP_TIMER_ARM(tp, TCPT_2MSL, tp->t_keepintvl); 620 else 621 tp = tcp_close(tp); 622 623 #ifdef TCP_DEBUG 624 if (tp && so->so_options & SO_DEBUG) 625 tcp_trace(TA_USER, ostate, tp, NULL, 626 PRU_SLOWTIMO | (TCPT_2MSL << 8)); 627 #endif 628 mutex_exit(softnet_lock); 629 KERNEL_UNLOCK_ONE(NULL); 630 } 631
Indexes created Sun Sep 21 20:09:37 GMT 2025