1 /*- 2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95 30 * $FreeBSD$ 31 */ 32 33 #include "opt_inet6.h" 34 #include "opt_tcpdebug.h" 35 #include "opt_tcp_sack.h" 36 37 #include <sys/param.h> 38 #include <sys/kernel.h> 39 #include <sys/lock.h> 40 #include <sys/mbuf.h> 41 #include <sys/mutex.h> 42 #include <sys/protosw.h> 43 #include <sys/socket.h> 44 #include <sys/socketvar.h> 45 #include <sys/sysctl.h> 46 #include <sys/systm.h> 47 48 #include <net/route.h> 49 50 #include <netinet/in.h> 51 #include <netinet/in_pcb.h> 52 #include <netinet/in_systm.h> 53 #ifdef INET6 54 #include <netinet6/in6_pcb.h> 55 #endif 56 #include <netinet/ip_var.h> 57 #include <netinet/tcp.h> 58 #include <netinet/tcp_fsm.h> 59 #include <netinet/tcp_timer.h> 60 #include <netinet/tcp_var.h> 61 #include <netinet/tcpip.h> 62 #ifdef TCPDEBUG 63 #include <netinet/tcp_debug.h> 64 #endif 65 66 int tcp_keepinit; 67 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW, 68 &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", ""); 69 70 int tcp_keepidle; 71 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW, 72 &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", ""); 73 74 int tcp_keepintvl; 75 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW, 76 &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", ""); 77 78 int tcp_delacktime; 79 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, 80 CTLTYPE_INT|CTLFLAG_RW, &tcp_delacktime, 0, sysctl_msec_to_ticks, "I", 81 "Time before a delayed ACK is sent"); 82 83 int tcp_msl; 84 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW, 85 &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime"); 86 87 int tcp_rexmit_min; 88 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW, 89 &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I", "Minimum Retransmission Timeout"); 90 91 int tcp_rexmit_slop; 92 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW, 93 &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I", "Retransmission Timer Slop"); 94 95 static int always_keepalive = 1; 96 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW, 97 &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections"); 98 99 static int tcp_keepcnt = TCPTV_KEEPCNT; 100 /* max idle probes */ 101 int tcp_maxpersistidle; 102 /* max idle time in persist */ 103 int tcp_maxidle; 104 105 /* 106 * Tcp protocol timeout routine called every 500 ms. 107 * Updates timestamps used for TCP 108 * causes finite state machine actions if timers expire. 109 */ 110 void 111 tcp_slowtimo() 112 { 113 114 tcp_maxidle = tcp_keepcnt * tcp_keepintvl; 115 INP_INFO_WLOCK(&tcbinfo); 116 (void) tcp_timer_2msl_tw(0); 117 INP_INFO_WUNLOCK(&tcbinfo); 118 } 119 120 int tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] = 121 { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 }; 122 123 int tcp_backoff[TCP_MAXRXTSHIFT + 1] = 124 { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 }; 125 126 static int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */ 127 128 static int tcp_timer_race; 129 SYSCTL_INT(_net_inet_tcp, OID_AUTO, timer_race, CTLFLAG_RD, &tcp_timer_race, 130 0, "Count of t_inpcb races on tcp_discardcb"); 131 132 /* 133 * TCP timer processing. 134 */ 135 136 void 137 tcp_timer_delack(xtp) 138 void *xtp; 139 { 140 struct tcpcb *tp = xtp; 141 struct inpcb *inp; 142 143 INP_INFO_RLOCK(&tcbinfo); 144 inp = tp->t_inpcb; 145 /* 146 * XXXRW: While this assert is in fact correct, bugs in the tcpcb 147 * tear-down mean we need it as a work-around for races between 148 * timers and tcp_discardcb(). 149 * 150 * KASSERT(inp != NULL, ("tcp_timer_delack: inp == NULL")); 151 */ 152 if (inp == NULL) { 153 tcp_timer_race++; 154 INP_INFO_RUNLOCK(&tcbinfo); 155 return; 156 } 157 INP_LOCK(inp); 158 INP_INFO_RUNLOCK(&tcbinfo); 159 if ((inp->inp_vflag & INP_DROPPED) || callout_pending(tp->tt_delack) 160 || !callout_active(tp->tt_delack)) { 161 INP_UNLOCK(inp); 162 return; 163 } 164 callout_deactivate(tp->tt_delack); 165 166 tp->t_flags |= TF_ACKNOW; 167 tcpstat.tcps_delack++; 168 (void) tcp_output(tp); 169 INP_UNLOCK(inp); 170 } 171 172 void 173 tcp_timer_2msl(xtp) 174 void *xtp; 175 { 176 struct tcpcb *tp = xtp; 177 struct inpcb *inp; 178 #ifdef TCPDEBUG 179 int ostate; 180 181 ostate = tp->t_state; 182 #endif 183 /* 184 * XXXRW: Does this actually happen? 185 */ 186 INP_INFO_WLOCK(&tcbinfo); 187 inp = tp->t_inpcb; 188 /* 189 * XXXRW: While this assert is in fact correct, bugs in the tcpcb 190 * tear-down mean we need it as a work-around for races between 191 * timers and tcp_discardcb(). 192 * 193 * KASSERT(inp != NULL, ("tcp_timer_2msl: inp == NULL")); 194 */ 195 if (inp == NULL) { 196 tcp_timer_race++; 197 INP_INFO_WUNLOCK(&tcbinfo); 198 return; 199 } 200 INP_LOCK(inp); 201 tcp_free_sackholes(tp); 202 if ((inp->inp_vflag & INP_DROPPED) || callout_pending(tp->tt_2msl) || 203 !callout_active(tp->tt_2msl)) { 204 INP_UNLOCK(tp->t_inpcb); 205 INP_INFO_WUNLOCK(&tcbinfo); 206 return; 207 } 208 callout_deactivate(tp->tt_2msl); 209 /* 210 * 2 MSL timeout in shutdown went off. If we're closed but 211 * still waiting for peer to close and connection has been idle 212 * too long, or if 2MSL time is up from TIME_WAIT, delete connection 213 * control block. Otherwise, check again in a bit. 214 */ 215 if (tp->t_state != TCPS_TIME_WAIT && 216 (ticks - tp->t_rcvtime) <= tcp_maxidle) 217 callout_reset(tp->tt_2msl, tcp_keepintvl, 218 tcp_timer_2msl, tp); 219 else 220 tp = tcp_close(tp); 221 222 #ifdef TCPDEBUG 223 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 224 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 225 PRU_SLOWTIMO); 226 #endif 227 if (tp != NULL) 228 INP_UNLOCK(inp); 229 INP_INFO_WUNLOCK(&tcbinfo); 230 } 231 232 /* 233 * The timed wait queue contains references to each of the TCP sessions 234 * currently in the TIME_WAIT state. The queue pointers, including the 235 * queue pointers in each tcptw structure, are protected using the global 236 * tcbinfo lock, which must be held over queue iteration and modification. 237 */ 238 static TAILQ_HEAD(, tcptw) twq_2msl; 239 240 void 241 tcp_timer_init(void) 242 { 243 244 TAILQ_INIT(&twq_2msl); 245 } 246 247 void 248 tcp_timer_2msl_reset(struct tcptw *tw, int rearm) 249 { 250 251 INP_INFO_WLOCK_ASSERT(&tcbinfo); 252 INP_LOCK_ASSERT(tw->tw_inpcb); 253 if (rearm) 254 TAILQ_REMOVE(&twq_2msl, tw, tw_2msl); 255 tw->tw_time = ticks + 2 * tcp_msl; 256 TAILQ_INSERT_TAIL(&twq_2msl, tw, tw_2msl); 257 } 258 259 void 260 tcp_timer_2msl_stop(struct tcptw *tw) 261 { 262 263 INP_INFO_WLOCK_ASSERT(&tcbinfo); 264 TAILQ_REMOVE(&twq_2msl, tw, tw_2msl); 265 } 266 267 struct tcptw * 268 tcp_timer_2msl_tw(int reuse) 269 { 270 struct tcptw *tw; 271 272 INP_INFO_WLOCK_ASSERT(&tcbinfo); 273 for (;;) { 274 tw = TAILQ_FIRST(&twq_2msl); 275 if (tw == NULL || (!reuse && tw->tw_time > ticks)) 276 break; 277 INP_LOCK(tw->tw_inpcb); 278 tcp_twclose(tw, reuse); 279 if (reuse) 280 return (tw); 281 } 282 return (NULL); 283 } 284 285 void 286 tcp_timer_keep(xtp) 287 void *xtp; 288 { 289 struct tcpcb *tp = xtp; 290 struct tcptemp *t_template; 291 struct inpcb *inp; 292 #ifdef TCPDEBUG 293 int ostate; 294 295 ostate = tp->t_state; 296 #endif 297 INP_INFO_WLOCK(&tcbinfo); 298 inp = tp->t_inpcb; 299 /* 300 * XXXRW: While this assert is in fact correct, bugs in the tcpcb 301 * tear-down mean we need it as a work-around for races between 302 * timers and tcp_discardcb(). 303 * 304 * KASSERT(inp != NULL, ("tcp_timer_keep: inp == NULL")); 305 */ 306 if (inp == NULL) { 307 tcp_timer_race++; 308 INP_INFO_WUNLOCK(&tcbinfo); 309 return; 310 } 311 INP_LOCK(inp); 312 if ((inp->inp_vflag & INP_DROPPED) || callout_pending(tp->tt_keep) 313 || !callout_active(tp->tt_keep)) { 314 INP_UNLOCK(inp); 315 INP_INFO_WUNLOCK(&tcbinfo); 316 return; 317 } 318 callout_deactivate(tp->tt_keep); 319 /* 320 * Keep-alive timer went off; send something 321 * or drop connection if idle for too long. 322 */ 323 tcpstat.tcps_keeptimeo++; 324 if (tp->t_state < TCPS_ESTABLISHED) 325 goto dropit; 326 if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) && 327 tp->t_state <= TCPS_CLOSING) { 328 if ((ticks - tp->t_rcvtime) >= tcp_keepidle + tcp_maxidle) 329 goto dropit; 330 /* 331 * Send a packet designed to force a response 332 * if the peer is up and reachable: 333 * either an ACK if the connection is still alive, 334 * or an RST if the peer has closed the connection 335 * due to timeout or reboot. 336 * Using sequence number tp->snd_una-1 337 * causes the transmitted zero-length segment 338 * to lie outside the receive window; 339 * by the protocol spec, this requires the 340 * correspondent TCP to respond. 341 */ 342 tcpstat.tcps_keepprobe++; 343 t_template = tcpip_maketemplate(inp); 344 if (t_template) { 345 tcp_respond(tp, t_template->tt_ipgen, 346 &t_template->tt_t, (struct mbuf *)NULL, 347 tp->rcv_nxt, tp->snd_una - 1, 0); 348 (void) m_free(dtom(t_template)); 349 } 350 callout_reset(tp->tt_keep, tcp_keepintvl, tcp_timer_keep, tp); 351 } else 352 callout_reset(tp->tt_keep, tcp_keepidle, tcp_timer_keep, tp); 353 354 #ifdef TCPDEBUG 355 if (inp->inp_socket->so_options & SO_DEBUG) 356 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 357 PRU_SLOWTIMO); 358 #endif 359 INP_UNLOCK(inp); 360 INP_INFO_WUNLOCK(&tcbinfo); 361 return; 362 363 dropit: 364 tcpstat.tcps_keepdrops++; 365 tp = tcp_drop(tp, ETIMEDOUT); 366 367 #ifdef TCPDEBUG 368 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 369 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 370 PRU_SLOWTIMO); 371 #endif 372 if (tp != NULL) 373 INP_UNLOCK(tp->t_inpcb); 374 INP_INFO_WUNLOCK(&tcbinfo); 375 } 376 377 void 378 tcp_timer_persist(xtp) 379 void *xtp; 380 { 381 struct tcpcb *tp = xtp; 382 struct inpcb *inp; 383 #ifdef TCPDEBUG 384 int ostate; 385 386 ostate = tp->t_state; 387 #endif 388 INP_INFO_WLOCK(&tcbinfo); 389 inp = tp->t_inpcb; 390 /* 391 * XXXRW: While this assert is in fact correct, bugs in the tcpcb 392 * tear-down mean we need it as a work-around for races between 393 * timers and tcp_discardcb(). 394 * 395 * KASSERT(inp != NULL, ("tcp_timer_persist: inp == NULL")); 396 */ 397 if (inp == NULL) { 398 tcp_timer_race++; 399 INP_INFO_WUNLOCK(&tcbinfo); 400 return; 401 } 402 INP_LOCK(inp); 403 if ((inp->inp_vflag & INP_DROPPED) || callout_pending(tp->tt_persist) 404 || !callout_active(tp->tt_persist)) { 405 INP_UNLOCK(inp); 406 INP_INFO_WUNLOCK(&tcbinfo); 407 return; 408 } 409 callout_deactivate(tp->tt_persist); 410 /* 411 * Persistance timer into zero window. 412 * Force a byte to be output, if possible. 413 */ 414 tcpstat.tcps_persisttimeo++; 415 /* 416 * Hack: if the peer is dead/unreachable, we do not 417 * time out if the window is closed. After a full 418 * backoff, drop the connection if the idle time 419 * (no responses to probes) reaches the maximum 420 * backoff that we would use if retransmitting. 421 */ 422 if (tp->t_rxtshift == TCP_MAXRXTSHIFT && 423 ((ticks - tp->t_rcvtime) >= tcp_maxpersistidle || 424 (ticks - tp->t_rcvtime) >= TCP_REXMTVAL(tp) * tcp_totbackoff)) { 425 tcpstat.tcps_persistdrop++; 426 tp = tcp_drop(tp, ETIMEDOUT); 427 goto out; 428 } 429 tcp_setpersist(tp); 430 tp->t_flags |= TF_FORCEDATA; 431 (void) tcp_output(tp); 432 tp->t_flags &= ~TF_FORCEDATA; 433 434 out: 435 #ifdef TCPDEBUG 436 if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG) 437 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO); 438 #endif 439 if (tp != NULL) 440 INP_UNLOCK(inp); 441 INP_INFO_WUNLOCK(&tcbinfo); 442 } 443 444 void 445 tcp_timer_rexmt(xtp) 446 void *xtp; 447 { 448 struct tcpcb *tp = xtp; 449 int rexmt; 450 int headlocked; 451 struct inpcb *inp; 452 #ifdef TCPDEBUG 453 int ostate; 454 455 ostate = tp->t_state; 456 #endif 457 INP_INFO_WLOCK(&tcbinfo); 458 headlocked = 1; 459 inp = tp->t_inpcb; 460 /* 461 * XXXRW: While this assert is in fact correct, bugs in the tcpcb 462 * tear-down mean we need it as a work-around for races between 463 * timers and tcp_discardcb(). 464 * 465 * KASSERT(inp != NULL, ("tcp_timer_rexmt: inp == NULL")); 466 */ 467 if (inp == NULL) { 468 tcp_timer_race++; 469 INP_INFO_WUNLOCK(&tcbinfo); 470 return; 471 } 472 INP_LOCK(inp); 473 if ((inp->inp_vflag & INP_DROPPED) || callout_pending(tp->tt_rexmt) 474 || !callout_active(tp->tt_rexmt)) { 475 INP_UNLOCK(inp); 476 INP_INFO_WUNLOCK(&tcbinfo); 477 return; 478 } 479 callout_deactivate(tp->tt_rexmt); 480 tcp_free_sackholes(tp); 481 /* 482 * Retransmission timer went off. Message has not 483 * been acked within retransmit interval. Back off 484 * to a longer retransmit interval and retransmit one segment. 485 */ 486 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { 487 tp->t_rxtshift = TCP_MAXRXTSHIFT; 488 tcpstat.tcps_timeoutdrop++; 489 tp = tcp_drop(tp, tp->t_softerror ? 490 tp->t_softerror : ETIMEDOUT); 491 goto out; 492 } 493 INP_INFO_WUNLOCK(&tcbinfo); 494 headlocked = 0; 495 if (tp->t_rxtshift == 1) { 496 /* 497 * first retransmit; record ssthresh and cwnd so they can 498 * be recovered if this turns out to be a "bad" retransmit. 499 * A retransmit is considered "bad" if an ACK for this 500 * segment is received within RTT/2 interval; the assumption 501 * here is that the ACK was already in flight. See 502 * "On Estimating End-to-End Network Path Properties" by 503 * Allman and Paxson for more details. 504 */ 505 tp->snd_cwnd_prev = tp->snd_cwnd; 506 tp->snd_ssthresh_prev = tp->snd_ssthresh; 507 tp->snd_recover_prev = tp->snd_recover; 508 if (IN_FASTRECOVERY(tp)) 509 tp->t_flags |= TF_WASFRECOVERY; 510 else 511 tp->t_flags &= ~TF_WASFRECOVERY; 512 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1)); 513 } 514 tcpstat.tcps_rexmttimeo++; 515 if (tp->t_state == TCPS_SYN_SENT) 516 rexmt = TCP_REXMTVAL(tp) * tcp_syn_backoff[tp->t_rxtshift]; 517 else 518 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; 519 TCPT_RANGESET(tp->t_rxtcur, rexmt, 520 tp->t_rttmin, TCPTV_REXMTMAX); 521 /* 522 * Disable rfc1323 if we havn't got any response to 523 * our third SYN to work-around some broken terminal servers 524 * (most of which have hopefully been retired) that have bad VJ 525 * header compression code which trashes TCP segments containing 526 * unknown-to-them TCP options. 527 */ 528 if ((tp->t_state == TCPS_SYN_SENT) && (tp->t_rxtshift == 3)) 529 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP); 530 /* 531 * If we backed off this far, our srtt estimate is probably bogus. 532 * Clobber it so we'll take the next rtt measurement as our srtt; 533 * move the current srtt into rttvar to keep the current 534 * retransmit times until then. 535 */ 536 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { 537 #ifdef INET6 538 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) 539 in6_losing(tp->t_inpcb); 540 else 541 #endif 542 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); 543 tp->t_srtt = 0; 544 } 545 tp->snd_nxt = tp->snd_una; 546 tp->snd_recover = tp->snd_max; 547 /* 548 * Force a segment to be sent. 549 */ 550 tp->t_flags |= TF_ACKNOW; 551 /* 552 * If timing a segment in this window, stop the timer. 553 */ 554 tp->t_rtttime = 0; 555 /* 556 * Close the congestion window down to one segment 557 * (we'll open it by one segment for each ack we get). 558 * Since we probably have a window's worth of unacked 559 * data accumulated, this "slow start" keeps us from 560 * dumping all that data as back-to-back packets (which 561 * might overwhelm an intermediate gateway). 562 * 563 * There are two phases to the opening: Initially we 564 * open by one mss on each ack. This makes the window 565 * size increase exponentially with time. If the 566 * window is larger than the path can handle, this 567 * exponential growth results in dropped packet(s) 568 * almost immediately. To get more time between 569 * drops but still "push" the network to take advantage 570 * of improving conditions, we switch from exponential 571 * to linear window opening at some threshhold size. 572 * For a threshhold, we use half the current window 573 * size, truncated to a multiple of the mss. 574 * 575 * (the minimum cwnd that will give us exponential 576 * growth is 2 mss. We don't allow the threshhold 577 * to go below this.) 578 */ 579 { 580 u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg; 581 if (win < 2) 582 win = 2; 583 tp->snd_cwnd = tp->t_maxseg; 584 tp->snd_ssthresh = win * tp->t_maxseg; 585 tp->t_dupacks = 0; 586 } 587 EXIT_FASTRECOVERY(tp); 588 (void) tcp_output(tp); 589 590 out: 591 #ifdef TCPDEBUG 592 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 593 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 594 PRU_SLOWTIMO); 595 #endif 596 if (tp != NULL) 597 INP_UNLOCK(inp); 598 if (headlocked) 599 INP_INFO_WUNLOCK(&tcbinfo); 600 } 601