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 /* 135 * XXXRW: Note that there is a minor race issue associated with rapid 136 * modification of the two components of tcp_maxidle. This could be 137 * corrected by introducing sysctl handlers for those two fields, 138 * sliding this update of tcp_maxidle under the tcbinfo lock, and 139 * acquiring that lock in the handlers. 140 */ 141 tcp_maxidle = tcp_keepcnt * tcp_keepintvl; 142 INP_INFO_WLOCK(&tcbinfo); 143 (void) tcp_timer_2msl_tw(0); 144 INP_INFO_WUNLOCK(&tcbinfo); 145 } 146 147 /* 148 * Cancel all timers for TCP tp. 149 * 150 * XXXRW: This appears to be unused. 151 */ 152 void 153 tcp_canceltimers(tp) 154 struct tcpcb *tp; 155 { 156 callout_stop(tp->tt_2msl); 157 callout_stop(tp->tt_persist); 158 callout_stop(tp->tt_keep); 159 callout_stop(tp->tt_rexmt); 160 } 161 162 int tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] = 163 { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 }; 164 165 int tcp_backoff[TCP_MAXRXTSHIFT + 1] = 166 { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 }; 167 168 static int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */ 169 170 /* 171 * TCP timer processing. 172 */ 173 174 void 175 tcp_timer_delack(xtp) 176 void *xtp; 177 { 178 struct tcpcb *tp = xtp; 179 struct inpcb *inp; 180 181 INP_INFO_RLOCK(&tcbinfo); 182 inp = tp->t_inpcb; 183 if (inp == NULL) { 184 INP_INFO_RUNLOCK(&tcbinfo); 185 return; 186 } 187 INP_LOCK(inp); 188 INP_INFO_RUNLOCK(&tcbinfo); 189 if (callout_pending(tp->tt_delack) || !callout_active(tp->tt_delack)) { 190 INP_UNLOCK(inp); 191 return; 192 } 193 callout_deactivate(tp->tt_delack); 194 195 tp->t_flags |= TF_ACKNOW; 196 tcpstat.tcps_delack++; 197 (void) tcp_output(tp); 198 INP_UNLOCK(inp); 199 } 200 201 void 202 tcp_timer_2msl(xtp) 203 void *xtp; 204 { 205 struct tcpcb *tp = xtp; 206 struct inpcb *inp; 207 #ifdef TCPDEBUG 208 int ostate; 209 210 ostate = tp->t_state; 211 #endif 212 INP_INFO_WLOCK(&tcbinfo); 213 inp = tp->t_inpcb; 214 if (inp == NULL) { 215 INP_INFO_WUNLOCK(&tcbinfo); 216 return; 217 } 218 INP_LOCK(inp); 219 tcp_free_sackholes(tp); 220 if (callout_pending(tp->tt_2msl) || !callout_active(tp->tt_2msl)) { 221 INP_UNLOCK(tp->t_inpcb); 222 INP_INFO_WUNLOCK(&tcbinfo); 223 return; 224 } 225 callout_deactivate(tp->tt_2msl); 226 /* 227 * 2 MSL timeout in shutdown went off. If we're closed but 228 * still waiting for peer to close and connection has been idle 229 * too long, or if 2MSL time is up from TIME_WAIT, delete connection 230 * control block. Otherwise, check again in a bit. 231 */ 232 if (tp->t_state != TCPS_TIME_WAIT && 233 (ticks - tp->t_rcvtime) <= tcp_maxidle) 234 callout_reset(tp->tt_2msl, tcp_keepintvl, 235 tcp_timer_2msl, tp); 236 else 237 tp = tcp_close(tp); 238 239 #ifdef TCPDEBUG 240 if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 241 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 242 PRU_SLOWTIMO); 243 #endif 244 if (tp) 245 INP_UNLOCK(inp); 246 INP_INFO_WUNLOCK(&tcbinfo); 247 } 248 249 /* 250 * The timed wait lists contain references to each of the TCP sessions 251 * currently TIME_WAIT state. The list pointers, including the list pointers 252 * in each tcptw structure, are protected using the global tcbinfo lock, 253 * which must be held over list iteration and modification. 254 */ 255 struct twlist { 256 LIST_HEAD(, tcptw) tw_list; 257 struct tcptw tw_tail; 258 }; 259 #define TWLIST_NLISTS 2 260 static struct twlist twl_2msl[TWLIST_NLISTS]; 261 static struct twlist *tw_2msl_list[] = { &twl_2msl[0], &twl_2msl[1], NULL }; 262 263 void 264 tcp_timer_init(void) 265 { 266 int i; 267 struct twlist *twl; 268 269 for (i = 0; i < TWLIST_NLISTS; i++) { 270 twl = &twl_2msl[i]; 271 LIST_INIT(&twl->tw_list); 272 LIST_INSERT_HEAD(&twl->tw_list, &twl->tw_tail, tw_2msl); 273 } 274 } 275 276 void 277 tcp_timer_2msl_reset(struct tcptw *tw, int timeo) 278 { 279 int i; 280 struct tcptw *tw_tail; 281 282 INP_INFO_WLOCK_ASSERT(&tcbinfo); 283 if (tw->tw_time != 0) 284 LIST_REMOVE(tw, tw_2msl); 285 tw->tw_time = timeo + ticks; 286 i = timeo > tcp_msl ? 1 : 0; 287 tw_tail = &twl_2msl[i].tw_tail; 288 LIST_INSERT_BEFORE(tw_tail, tw, tw_2msl); 289 } 290 291 void 292 tcp_timer_2msl_stop(struct tcptw *tw) 293 { 294 295 INP_INFO_WLOCK_ASSERT(&tcbinfo); 296 if (tw->tw_time != 0) 297 LIST_REMOVE(tw, tw_2msl); 298 } 299 300 struct tcptw * 301 tcp_timer_2msl_tw(int reuse) 302 { 303 struct tcptw *tw, *tw_tail; 304 struct twlist *twl; 305 int i; 306 307 INP_INFO_WLOCK_ASSERT(&tcbinfo); 308 for (i = 0; i < 2; i++) { 309 twl = tw_2msl_list[i]; 310 tw_tail = &twl->tw_tail; 311 for (;;) { 312 tw = LIST_FIRST(&twl->tw_list); 313 if (tw == tw_tail || (!reuse && tw->tw_time > ticks)) 314 break; 315 INP_LOCK(tw->tw_inpcb); 316 if (tcp_twclose(tw, reuse) != NULL) 317 return (tw); 318 } 319 } 320 return (NULL); 321 } 322 323 void 324 tcp_timer_keep(xtp) 325 void *xtp; 326 { 327 struct tcpcb *tp = xtp; 328 struct tcptemp *t_template; 329 int s; 330 struct inpcb *inp; 331 #ifdef TCPDEBUG 332 int ostate; 333 334 ostate = tp->t_state; 335 #endif 336 s = splnet(); 337 INP_INFO_WLOCK(&tcbinfo); 338 inp = tp->t_inpcb; 339 if (!inp) { 340 INP_INFO_WUNLOCK(&tcbinfo); 341 splx(s); 342 return; 343 } 344 INP_LOCK(inp); 345 if (callout_pending(tp->tt_keep) || !callout_active(tp->tt_keep)) { 346 INP_UNLOCK(inp); 347 INP_INFO_WUNLOCK(&tcbinfo); 348 splx(s); 349 return; 350 } 351 callout_deactivate(tp->tt_keep); 352 /* 353 * Keep-alive timer went off; send something 354 * or drop connection if idle for too long. 355 */ 356 tcpstat.tcps_keeptimeo++; 357 if (tp->t_state < TCPS_ESTABLISHED) 358 goto dropit; 359 if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) && 360 tp->t_state <= TCPS_CLOSING) { 361 if ((ticks - tp->t_rcvtime) >= tcp_keepidle + tcp_maxidle) 362 goto dropit; 363 /* 364 * Send a packet designed to force a response 365 * if the peer is up and reachable: 366 * either an ACK if the connection is still alive, 367 * or an RST if the peer has closed the connection 368 * due to timeout or reboot. 369 * Using sequence number tp->snd_una-1 370 * causes the transmitted zero-length segment 371 * to lie outside the receive window; 372 * by the protocol spec, this requires the 373 * correspondent TCP to respond. 374 */ 375 tcpstat.tcps_keepprobe++; 376 t_template = tcpip_maketemplate(inp); 377 if (t_template) { 378 tcp_respond(tp, t_template->tt_ipgen, 379 &t_template->tt_t, (struct mbuf *)NULL, 380 tp->rcv_nxt, tp->snd_una - 1, 0); 381 (void) m_free(dtom(t_template)); 382 } 383 callout_reset(tp->tt_keep, tcp_keepintvl, tcp_timer_keep, tp); 384 } else 385 callout_reset(tp->tt_keep, tcp_keepidle, tcp_timer_keep, tp); 386 387 #ifdef TCPDEBUG 388 if (inp->inp_socket->so_options & SO_DEBUG) 389 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 390 PRU_SLOWTIMO); 391 #endif 392 INP_UNLOCK(inp); 393 INP_INFO_WUNLOCK(&tcbinfo); 394 splx(s); 395 return; 396 397 dropit: 398 tcpstat.tcps_keepdrops++; 399 tp = tcp_drop(tp, ETIMEDOUT); 400 401 #ifdef TCPDEBUG 402 if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 403 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 404 PRU_SLOWTIMO); 405 #endif 406 if (tp) 407 INP_UNLOCK(tp->t_inpcb); 408 INP_INFO_WUNLOCK(&tcbinfo); 409 splx(s); 410 } 411 412 void 413 tcp_timer_persist(xtp) 414 void *xtp; 415 { 416 struct tcpcb *tp = xtp; 417 int s; 418 struct inpcb *inp; 419 #ifdef TCPDEBUG 420 int ostate; 421 422 ostate = tp->t_state; 423 #endif 424 s = splnet(); 425 INP_INFO_WLOCK(&tcbinfo); 426 inp = tp->t_inpcb; 427 if (!inp) { 428 INP_INFO_WUNLOCK(&tcbinfo); 429 splx(s); 430 return; 431 } 432 INP_LOCK(inp); 433 if (callout_pending(tp->tt_persist) || !callout_active(tp->tt_persist)){ 434 INP_UNLOCK(inp); 435 INP_INFO_WUNLOCK(&tcbinfo); 436 splx(s); 437 return; 438 } 439 callout_deactivate(tp->tt_persist); 440 /* 441 * Persistance timer into zero window. 442 * Force a byte to be output, if possible. 443 */ 444 tcpstat.tcps_persisttimeo++; 445 /* 446 * Hack: if the peer is dead/unreachable, we do not 447 * time out if the window is closed. After a full 448 * backoff, drop the connection if the idle time 449 * (no responses to probes) reaches the maximum 450 * backoff that we would use if retransmitting. 451 */ 452 if (tp->t_rxtshift == TCP_MAXRXTSHIFT && 453 ((ticks - tp->t_rcvtime) >= tcp_maxpersistidle || 454 (ticks - tp->t_rcvtime) >= TCP_REXMTVAL(tp) * tcp_totbackoff)) { 455 tcpstat.tcps_persistdrop++; 456 tp = tcp_drop(tp, ETIMEDOUT); 457 goto out; 458 } 459 tcp_setpersist(tp); 460 tp->t_force = 1; 461 (void) tcp_output(tp); 462 tp->t_force = 0; 463 464 out: 465 #ifdef TCPDEBUG 466 if (tp && tp->t_inpcb->inp_socket->so_options & SO_DEBUG) 467 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 468 PRU_SLOWTIMO); 469 #endif 470 if (tp) 471 INP_UNLOCK(inp); 472 INP_INFO_WUNLOCK(&tcbinfo); 473 splx(s); 474 } 475 476 void 477 tcp_timer_rexmt(xtp) 478 void *xtp; 479 { 480 struct tcpcb *tp = xtp; 481 int s; 482 int rexmt; 483 int headlocked; 484 struct inpcb *inp; 485 #ifdef TCPDEBUG 486 int ostate; 487 488 ostate = tp->t_state; 489 #endif 490 s = splnet(); 491 INP_INFO_WLOCK(&tcbinfo); 492 headlocked = 1; 493 inp = tp->t_inpcb; 494 if (!inp) { 495 INP_INFO_WUNLOCK(&tcbinfo); 496 splx(s); 497 return; 498 } 499 INP_LOCK(inp); 500 if (callout_pending(tp->tt_rexmt) || !callout_active(tp->tt_rexmt)) { 501 INP_UNLOCK(inp); 502 INP_INFO_WUNLOCK(&tcbinfo); 503 splx(s); 504 return; 505 } 506 callout_deactivate(tp->tt_rexmt); 507 tcp_free_sackholes(tp); 508 /* 509 * Retransmission timer went off. Message has not 510 * been acked within retransmit interval. Back off 511 * to a longer retransmit interval and retransmit one segment. 512 */ 513 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { 514 tp->t_rxtshift = TCP_MAXRXTSHIFT; 515 tcpstat.tcps_timeoutdrop++; 516 tp = tcp_drop(tp, tp->t_softerror ? 517 tp->t_softerror : ETIMEDOUT); 518 goto out; 519 } 520 INP_INFO_WUNLOCK(&tcbinfo); 521 headlocked = 0; 522 if (tp->t_rxtshift == 1) { 523 /* 524 * first retransmit; record ssthresh and cwnd so they can 525 * be recovered if this turns out to be a "bad" retransmit. 526 * A retransmit is considered "bad" if an ACK for this 527 * segment is received within RTT/2 interval; the assumption 528 * here is that the ACK was already in flight. See 529 * "On Estimating End-to-End Network Path Properties" by 530 * Allman and Paxson for more details. 531 */ 532 tp->snd_cwnd_prev = tp->snd_cwnd; 533 tp->snd_ssthresh_prev = tp->snd_ssthresh; 534 tp->snd_recover_prev = tp->snd_recover; 535 if (IN_FASTRECOVERY(tp)) 536 tp->t_flags |= TF_WASFRECOVERY; 537 else 538 tp->t_flags &= ~TF_WASFRECOVERY; 539 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1)); 540 } 541 tcpstat.tcps_rexmttimeo++; 542 if (tp->t_state == TCPS_SYN_SENT) 543 rexmt = TCP_REXMTVAL(tp) * tcp_syn_backoff[tp->t_rxtshift]; 544 else 545 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; 546 TCPT_RANGESET(tp->t_rxtcur, rexmt, 547 tp->t_rttmin, TCPTV_REXMTMAX); 548 /* 549 * Disable rfc1323 if we havn't got any response to 550 * our third SYN to work-around some broken terminal servers 551 * (most of which have hopefully been retired) that have bad VJ 552 * header compression code which trashes TCP segments containing 553 * unknown-to-them TCP options. 554 */ 555 if ((tp->t_state == TCPS_SYN_SENT) && (tp->t_rxtshift == 3)) 556 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP); 557 /* 558 * If we backed off this far, our srtt estimate is probably bogus. 559 * Clobber it so we'll take the next rtt measurement as our srtt; 560 * move the current srtt into rttvar to keep the current 561 * retransmit times until then. 562 */ 563 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { 564 #ifdef INET6 565 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) 566 in6_losing(tp->t_inpcb); 567 else 568 #endif 569 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); 570 tp->t_srtt = 0; 571 } 572 tp->snd_nxt = tp->snd_una; 573 tp->snd_recover = tp->snd_max; 574 /* 575 * Force a segment to be sent. 576 */ 577 tp->t_flags |= TF_ACKNOW; 578 /* 579 * If timing a segment in this window, stop the timer. 580 */ 581 tp->t_rtttime = 0; 582 /* 583 * Close the congestion window down to one segment 584 * (we'll open it by one segment for each ack we get). 585 * Since we probably have a window's worth of unacked 586 * data accumulated, this "slow start" keeps us from 587 * dumping all that data as back-to-back packets (which 588 * might overwhelm an intermediate gateway). 589 * 590 * There are two phases to the opening: Initially we 591 * open by one mss on each ack. This makes the window 592 * size increase exponentially with time. If the 593 * window is larger than the path can handle, this 594 * exponential growth results in dropped packet(s) 595 * almost immediately. To get more time between 596 * drops but still "push" the network to take advantage 597 * of improving conditions, we switch from exponential 598 * to linear window opening at some threshhold size. 599 * For a threshhold, we use half the current window 600 * size, truncated to a multiple of the mss. 601 * 602 * (the minimum cwnd that will give us exponential 603 * growth is 2 mss. We don't allow the threshhold 604 * to go below this.) 605 */ 606 { 607 u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg; 608 if (win < 2) 609 win = 2; 610 tp->snd_cwnd = tp->t_maxseg; 611 tp->snd_ssthresh = win * tp->t_maxseg; 612 tp->t_dupacks = 0; 613 } 614 EXIT_FASTRECOVERY(tp); 615 (void) tcp_output(tp); 616 617 out: 618 #ifdef TCPDEBUG 619 if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 620 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 621 PRU_SLOWTIMO); 622 #endif 623 if (tp) 624 INP_UNLOCK(inp); 625 if (headlocked) 626 INP_INFO_WUNLOCK(&tcbinfo); 627 splx(s); 628 } 629