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 static int 67 sysctl_msec_to_ticks(SYSCTL_HANDLER_ARGS) 68 { 69 int error, s, tt; 70 71 tt = *(int *)oidp->oid_arg1; 72 s = (int)((int64_t)tt * 1000 / hz); 73 74 error = sysctl_handle_int(oidp, &s, 0, req); 75 if (error || !req->newptr) 76 return (error); 77 78 tt = (int)((int64_t)s * hz / 1000); 79 if (tt < 1) 80 return (EINVAL); 81 82 *(int *)oidp->oid_arg1 = tt; 83 return (0); 84 } 85 86 int tcp_keepinit; 87 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW, 88 &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", ""); 89 90 int tcp_keepidle; 91 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW, 92 &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", ""); 93 94 int tcp_keepintvl; 95 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW, 96 &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", ""); 97 98 int tcp_delacktime; 99 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, 100 CTLTYPE_INT|CTLFLAG_RW, &tcp_delacktime, 0, sysctl_msec_to_ticks, "I", 101 "Time before a delayed ACK is sent"); 102 103 int tcp_msl; 104 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW, 105 &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime"); 106 107 int tcp_rexmit_min; 108 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW, 109 &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I", "Minimum Retransmission Timeout"); 110 111 int tcp_rexmit_slop; 112 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW, 113 &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I", "Retransmission Timer Slop"); 114 115 static int always_keepalive = 1; 116 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW, 117 &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections"); 118 119 static int tcp_keepcnt = TCPTV_KEEPCNT; 120 /* max idle probes */ 121 int tcp_maxpersistidle; 122 /* max idle time in persist */ 123 int tcp_maxidle; 124 125 /* 126 * Tcp protocol timeout routine called every 500 ms. 127 * Updates timestamps used for TCP 128 * causes finite state machine actions if timers expire. 129 */ 130 void 131 tcp_slowtimo() 132 { 133 134 tcp_maxidle = tcp_keepcnt * tcp_keepintvl; 135 INP_INFO_WLOCK(&tcbinfo); 136 (void) tcp_timer_2msl_tw(0); 137 INP_INFO_WUNLOCK(&tcbinfo); 138 } 139 140 /* 141 * Cancel all timers for TCP tp. 142 * 143 * XXXRW: This appears to be unused. 144 */ 145 void 146 tcp_canceltimers(tp) 147 struct tcpcb *tp; 148 { 149 callout_stop(tp->tt_2msl); 150 callout_stop(tp->tt_persist); 151 callout_stop(tp->tt_keep); 152 callout_stop(tp->tt_rexmt); 153 } 154 155 int tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] = 156 { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 }; 157 158 int tcp_backoff[TCP_MAXRXTSHIFT + 1] = 159 { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 }; 160 161 static int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */ 162 163 /* 164 * TCP timer processing. 165 */ 166 167 void 168 tcp_timer_delack(xtp) 169 void *xtp; 170 { 171 struct tcpcb *tp = xtp; 172 struct inpcb *inp; 173 174 INP_INFO_RLOCK(&tcbinfo); 175 inp = tp->t_inpcb; 176 if (inp == NULL) { 177 INP_INFO_RUNLOCK(&tcbinfo); 178 return; 179 } 180 INP_LOCK(inp); 181 INP_INFO_RUNLOCK(&tcbinfo); 182 if (callout_pending(tp->tt_delack) || !callout_active(tp->tt_delack)) { 183 INP_UNLOCK(inp); 184 return; 185 } 186 callout_deactivate(tp->tt_delack); 187 188 tp->t_flags |= TF_ACKNOW; 189 tcpstat.tcps_delack++; 190 (void) tcp_output(tp); 191 INP_UNLOCK(inp); 192 } 193 194 void 195 tcp_timer_2msl(xtp) 196 void *xtp; 197 { 198 struct tcpcb *tp = xtp; 199 struct inpcb *inp; 200 #ifdef TCPDEBUG 201 int ostate; 202 203 ostate = tp->t_state; 204 #endif 205 INP_INFO_WLOCK(&tcbinfo); 206 inp = tp->t_inpcb; 207 if (inp == NULL) { 208 INP_INFO_WUNLOCK(&tcbinfo); 209 return; 210 } 211 INP_LOCK(inp); 212 tcp_free_sackholes(tp); 213 if (callout_pending(tp->tt_2msl) || !callout_active(tp->tt_2msl)) { 214 INP_UNLOCK(tp->t_inpcb); 215 INP_INFO_WUNLOCK(&tcbinfo); 216 return; 217 } 218 callout_deactivate(tp->tt_2msl); 219 /* 220 * 2 MSL timeout in shutdown went off. If we're closed but 221 * still waiting for peer to close and connection has been idle 222 * too long, or if 2MSL time is up from TIME_WAIT, delete connection 223 * control block. Otherwise, check again in a bit. 224 */ 225 if (tp->t_state != TCPS_TIME_WAIT && 226 (ticks - tp->t_rcvtime) <= tcp_maxidle) 227 callout_reset(tp->tt_2msl, tcp_keepintvl, 228 tcp_timer_2msl, tp); 229 else 230 tp = tcp_close(tp); 231 232 #ifdef TCPDEBUG 233 if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 234 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 235 PRU_SLOWTIMO); 236 #endif 237 if (tp) 238 INP_UNLOCK(inp); 239 INP_INFO_WUNLOCK(&tcbinfo); 240 } 241 242 /* 243 * The timed wait lists contain references to each of the TCP sessions 244 * currently TIME_WAIT state. The list pointers, including the list pointers 245 * in each tcptw structure, are protected using the global tcbinfo lock, 246 * which must be held over list iteration and modification. 247 */ 248 struct twlist { 249 LIST_HEAD(, tcptw) tw_list; 250 struct tcptw tw_tail; 251 }; 252 #define TWLIST_NLISTS 2 253 static struct twlist twl_2msl[TWLIST_NLISTS]; 254 static struct twlist *tw_2msl_list[] = { &twl_2msl[0], &twl_2msl[1], NULL }; 255 256 void 257 tcp_timer_init(void) 258 { 259 int i; 260 struct twlist *twl; 261 262 for (i = 0; i < TWLIST_NLISTS; i++) { 263 twl = &twl_2msl[i]; 264 LIST_INIT(&twl->tw_list); 265 LIST_INSERT_HEAD(&twl->tw_list, &twl->tw_tail, tw_2msl); 266 } 267 } 268 269 void 270 tcp_timer_2msl_reset(struct tcptw *tw, int timeo) 271 { 272 int i; 273 struct tcptw *tw_tail; 274 275 INP_INFO_WLOCK_ASSERT(&tcbinfo); 276 INP_LOCK_ASSERT(tw->tw_inpcb); 277 if (tw->tw_time != 0) 278 LIST_REMOVE(tw, tw_2msl); 279 tw->tw_time = timeo + ticks; 280 i = timeo > tcp_msl ? 1 : 0; 281 tw_tail = &twl_2msl[i].tw_tail; 282 LIST_INSERT_BEFORE(tw_tail, tw, tw_2msl); 283 } 284 285 void 286 tcp_timer_2msl_stop(struct tcptw *tw) 287 { 288 289 INP_INFO_WLOCK_ASSERT(&tcbinfo); 290 if (tw->tw_time != 0) 291 LIST_REMOVE(tw, tw_2msl); 292 } 293 294 struct tcptw * 295 tcp_timer_2msl_tw(int reuse) 296 { 297 struct tcptw *tw, *tw_tail; 298 struct twlist *twl; 299 int i; 300 301 INP_INFO_WLOCK_ASSERT(&tcbinfo); 302 for (i = 0; i < 2; i++) { 303 twl = tw_2msl_list[i]; 304 tw_tail = &twl->tw_tail; 305 for (;;) { 306 tw = LIST_FIRST(&twl->tw_list); 307 if (tw == tw_tail || (!reuse && tw->tw_time > ticks)) 308 break; 309 INP_LOCK(tw->tw_inpcb); 310 if (tcp_twclose(tw, reuse) != NULL) 311 return (tw); 312 } 313 } 314 return (NULL); 315 } 316 317 void 318 tcp_timer_keep(xtp) 319 void *xtp; 320 { 321 struct tcpcb *tp = xtp; 322 struct tcptemp *t_template; 323 int s; 324 struct inpcb *inp; 325 #ifdef TCPDEBUG 326 int ostate; 327 328 ostate = tp->t_state; 329 #endif 330 s = splnet(); 331 INP_INFO_WLOCK(&tcbinfo); 332 inp = tp->t_inpcb; 333 if (!inp) { 334 INP_INFO_WUNLOCK(&tcbinfo); 335 splx(s); 336 return; 337 } 338 INP_LOCK(inp); 339 if (callout_pending(tp->tt_keep) || !callout_active(tp->tt_keep)) { 340 INP_UNLOCK(inp); 341 INP_INFO_WUNLOCK(&tcbinfo); 342 splx(s); 343 return; 344 } 345 callout_deactivate(tp->tt_keep); 346 /* 347 * Keep-alive timer went off; send something 348 * or drop connection if idle for too long. 349 */ 350 tcpstat.tcps_keeptimeo++; 351 if (tp->t_state < TCPS_ESTABLISHED) 352 goto dropit; 353 if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) && 354 tp->t_state <= TCPS_CLOSING) { 355 if ((ticks - tp->t_rcvtime) >= tcp_keepidle + tcp_maxidle) 356 goto dropit; 357 /* 358 * Send a packet designed to force a response 359 * if the peer is up and reachable: 360 * either an ACK if the connection is still alive, 361 * or an RST if the peer has closed the connection 362 * due to timeout or reboot. 363 * Using sequence number tp->snd_una-1 364 * causes the transmitted zero-length segment 365 * to lie outside the receive window; 366 * by the protocol spec, this requires the 367 * correspondent TCP to respond. 368 */ 369 tcpstat.tcps_keepprobe++; 370 t_template = tcpip_maketemplate(inp); 371 if (t_template) { 372 tcp_respond(tp, t_template->tt_ipgen, 373 &t_template->tt_t, (struct mbuf *)NULL, 374 tp->rcv_nxt, tp->snd_una - 1, 0); 375 (void) m_free(dtom(t_template)); 376 } 377 callout_reset(tp->tt_keep, tcp_keepintvl, tcp_timer_keep, tp); 378 } else 379 callout_reset(tp->tt_keep, tcp_keepidle, tcp_timer_keep, tp); 380 381 #ifdef TCPDEBUG 382 if (inp->inp_socket->so_options & SO_DEBUG) 383 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 384 PRU_SLOWTIMO); 385 #endif 386 INP_UNLOCK(inp); 387 INP_INFO_WUNLOCK(&tcbinfo); 388 splx(s); 389 return; 390 391 dropit: 392 tcpstat.tcps_keepdrops++; 393 tp = tcp_drop(tp, ETIMEDOUT); 394 395 #ifdef TCPDEBUG 396 if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 397 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 398 PRU_SLOWTIMO); 399 #endif 400 if (tp) 401 INP_UNLOCK(tp->t_inpcb); 402 INP_INFO_WUNLOCK(&tcbinfo); 403 splx(s); 404 } 405 406 void 407 tcp_timer_persist(xtp) 408 void *xtp; 409 { 410 struct tcpcb *tp = xtp; 411 int s; 412 struct inpcb *inp; 413 #ifdef TCPDEBUG 414 int ostate; 415 416 ostate = tp->t_state; 417 #endif 418 s = splnet(); 419 INP_INFO_WLOCK(&tcbinfo); 420 inp = tp->t_inpcb; 421 if (!inp) { 422 INP_INFO_WUNLOCK(&tcbinfo); 423 splx(s); 424 return; 425 } 426 INP_LOCK(inp); 427 if (callout_pending(tp->tt_persist) || !callout_active(tp->tt_persist)){ 428 INP_UNLOCK(inp); 429 INP_INFO_WUNLOCK(&tcbinfo); 430 splx(s); 431 return; 432 } 433 callout_deactivate(tp->tt_persist); 434 /* 435 * Persistance timer into zero window. 436 * Force a byte to be output, if possible. 437 */ 438 tcpstat.tcps_persisttimeo++; 439 /* 440 * Hack: if the peer is dead/unreachable, we do not 441 * time out if the window is closed. After a full 442 * backoff, drop the connection if the idle time 443 * (no responses to probes) reaches the maximum 444 * backoff that we would use if retransmitting. 445 */ 446 if (tp->t_rxtshift == TCP_MAXRXTSHIFT && 447 ((ticks - tp->t_rcvtime) >= tcp_maxpersistidle || 448 (ticks - tp->t_rcvtime) >= TCP_REXMTVAL(tp) * tcp_totbackoff)) { 449 tcpstat.tcps_persistdrop++; 450 tp = tcp_drop(tp, ETIMEDOUT); 451 goto out; 452 } 453 tcp_setpersist(tp); 454 tp->t_force = 1; 455 (void) tcp_output(tp); 456 tp->t_force = 0; 457 458 out: 459 #ifdef TCPDEBUG 460 if (tp && tp->t_inpcb->inp_socket->so_options & SO_DEBUG) 461 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 462 PRU_SLOWTIMO); 463 #endif 464 if (tp) 465 INP_UNLOCK(inp); 466 INP_INFO_WUNLOCK(&tcbinfo); 467 splx(s); 468 } 469 470 void 471 tcp_timer_rexmt(xtp) 472 void *xtp; 473 { 474 struct tcpcb *tp = xtp; 475 int s; 476 int rexmt; 477 int headlocked; 478 struct inpcb *inp; 479 #ifdef TCPDEBUG 480 int ostate; 481 482 ostate = tp->t_state; 483 #endif 484 s = splnet(); 485 INP_INFO_WLOCK(&tcbinfo); 486 headlocked = 1; 487 inp = tp->t_inpcb; 488 if (!inp) { 489 INP_INFO_WUNLOCK(&tcbinfo); 490 splx(s); 491 return; 492 } 493 INP_LOCK(inp); 494 if (callout_pending(tp->tt_rexmt) || !callout_active(tp->tt_rexmt)) { 495 INP_UNLOCK(inp); 496 INP_INFO_WUNLOCK(&tcbinfo); 497 splx(s); 498 return; 499 } 500 callout_deactivate(tp->tt_rexmt); 501 tcp_free_sackholes(tp); 502 /* 503 * Retransmission timer went off. Message has not 504 * been acked within retransmit interval. Back off 505 * to a longer retransmit interval and retransmit one segment. 506 */ 507 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { 508 tp->t_rxtshift = TCP_MAXRXTSHIFT; 509 tcpstat.tcps_timeoutdrop++; 510 tp = tcp_drop(tp, tp->t_softerror ? 511 tp->t_softerror : ETIMEDOUT); 512 goto out; 513 } 514 INP_INFO_WUNLOCK(&tcbinfo); 515 headlocked = 0; 516 if (tp->t_rxtshift == 1) { 517 /* 518 * first retransmit; record ssthresh and cwnd so they can 519 * be recovered if this turns out to be a "bad" retransmit. 520 * A retransmit is considered "bad" if an ACK for this 521 * segment is received within RTT/2 interval; the assumption 522 * here is that the ACK was already in flight. See 523 * "On Estimating End-to-End Network Path Properties" by 524 * Allman and Paxson for more details. 525 */ 526 tp->snd_cwnd_prev = tp->snd_cwnd; 527 tp->snd_ssthresh_prev = tp->snd_ssthresh; 528 tp->snd_recover_prev = tp->snd_recover; 529 if (IN_FASTRECOVERY(tp)) 530 tp->t_flags |= TF_WASFRECOVERY; 531 else 532 tp->t_flags &= ~TF_WASFRECOVERY; 533 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1)); 534 } 535 tcpstat.tcps_rexmttimeo++; 536 if (tp->t_state == TCPS_SYN_SENT) 537 rexmt = TCP_REXMTVAL(tp) * tcp_syn_backoff[tp->t_rxtshift]; 538 else 539 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; 540 TCPT_RANGESET(tp->t_rxtcur, rexmt, 541 tp->t_rttmin, TCPTV_REXMTMAX); 542 /* 543 * Disable rfc1323 if we havn't got any response to 544 * our third SYN to work-around some broken terminal servers 545 * (most of which have hopefully been retired) that have bad VJ 546 * header compression code which trashes TCP segments containing 547 * unknown-to-them TCP options. 548 */ 549 if ((tp->t_state == TCPS_SYN_SENT) && (tp->t_rxtshift == 3)) 550 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP); 551 /* 552 * If we backed off this far, our srtt estimate is probably bogus. 553 * Clobber it so we'll take the next rtt measurement as our srtt; 554 * move the current srtt into rttvar to keep the current 555 * retransmit times until then. 556 */ 557 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { 558 #ifdef INET6 559 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) 560 in6_losing(tp->t_inpcb); 561 else 562 #endif 563 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); 564 tp->t_srtt = 0; 565 } 566 tp->snd_nxt = tp->snd_una; 567 tp->snd_recover = tp->snd_max; 568 /* 569 * Force a segment to be sent. 570 */ 571 tp->t_flags |= TF_ACKNOW; 572 /* 573 * If timing a segment in this window, stop the timer. 574 */ 575 tp->t_rtttime = 0; 576 /* 577 * Close the congestion window down to one segment 578 * (we'll open it by one segment for each ack we get). 579 * Since we probably have a window's worth of unacked 580 * data accumulated, this "slow start" keeps us from 581 * dumping all that data as back-to-back packets (which 582 * might overwhelm an intermediate gateway). 583 * 584 * There are two phases to the opening: Initially we 585 * open by one mss on each ack. This makes the window 586 * size increase exponentially with time. If the 587 * window is larger than the path can handle, this 588 * exponential growth results in dropped packet(s) 589 * almost immediately. To get more time between 590 * drops but still "push" the network to take advantage 591 * of improving conditions, we switch from exponential 592 * to linear window opening at some threshhold size. 593 * For a threshhold, we use half the current window 594 * size, truncated to a multiple of the mss. 595 * 596 * (the minimum cwnd that will give us exponential 597 * growth is 2 mss. We don't allow the threshhold 598 * to go below this.) 599 */ 600 { 601 u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg; 602 if (win < 2) 603 win = 2; 604 tp->snd_cwnd = tp->t_maxseg; 605 tp->snd_ssthresh = win * tp->t_maxseg; 606 tp->t_dupacks = 0; 607 } 608 EXIT_FASTRECOVERY(tp); 609 (void) tcp_output(tp); 610 611 out: 612 #ifdef TCPDEBUG 613 if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 614 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 615 PRU_SLOWTIMO); 616 #endif 617 if (tp) 618 INP_UNLOCK(inp); 619 if (headlocked) 620 INP_INFO_WUNLOCK(&tcbinfo); 621 splx(s); 622 } 623