sys/netinet/tcp_timer.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
   5  *      The Regents of the University of California.  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 University 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 REGENTS 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 REGENTS 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  *      @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95
  32  */
  33
  34 #include <sys/cdefs.h>
  35 __FBSDID("$FreeBSD$");
  36
  37 #include "opt_inet.h"
  38 #include "opt_inet6.h"
  39 #include "opt_tcpdebug.h"
  40 #include "opt_rss.h"
  41
  42 #include <sys/param.h>
  43 #include <sys/kernel.h>
  44 #include <sys/lock.h>
  45 #include <sys/mbuf.h>
  46 #include <sys/mutex.h>
  47 #include <sys/protosw.h>
  48 #include <sys/smp.h>
  49 #include <sys/socket.h>
  50 #include <sys/socketvar.h>
  51 #include <sys/sysctl.h>
  52 #include <sys/systm.h>
  53
  54 #include <net/if.h>
  55 #include <net/route.h>
  56 #include <net/rss_config.h>
  57 #include <net/vnet.h>
  58 #include <net/netisr.h>
  59
  60 #include <netinet/in.h>
  61 #include <netinet/in_kdtrace.h>
  62 #include <netinet/in_pcb.h>
  63 #include <netinet/in_rss.h>
  64 #include <netinet/in_systm.h>
  65 #ifdef INET6
  66 #include <netinet6/in6_pcb.h>
  67 #endif
  68 #include <netinet/ip_var.h>
  69 #include <netinet/tcp.h>
  70 #include <netinet/tcp_fsm.h>
  71 #include <netinet/tcp_log_buf.h>
  72 #include <netinet/tcp_timer.h>
  73 #include <netinet/tcp_var.h>
  74 #include <netinet/tcp_seq.h>
  75 #include <netinet/cc/cc.h>
  76 #ifdef INET6
  77 #include <netinet6/tcp6_var.h>
  78 #endif
  79 #include <netinet/tcpip.h>
  80 #ifdef TCPDEBUG
  81 #include <netinet/tcp_debug.h>
  82 #endif
  83
  84 int    tcp_persmin;
  85 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmin, CTLTYPE_INT|CTLFLAG_RW,
  86     &tcp_persmin, 0, sysctl_msec_to_ticks, "I", "minimum persistence interval");
  87
  88 int    tcp_persmax;
  89 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmax, CTLTYPE_INT|CTLFLAG_RW,
  90     &tcp_persmax, 0, sysctl_msec_to_ticks, "I", "maximum persistence interval");
  91
  92 int     tcp_keepinit;
  93 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
  94     &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "time to establish connection");
  95
  96 int     tcp_keepidle;
  97 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
  98     &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "time before keepalive probes begin");
  99
 100 int     tcp_keepintvl;
 101 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
 102     &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "time between keepalive probes");
 103
 104 int     tcp_delacktime;
 105 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW,
 106     &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
 107     "Time before a delayed ACK is sent");
 108
 109 int     tcp_msl;
 110 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
 111     &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
 112
 113 int     tcp_rexmit_initial;
 114 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_initial, CTLTYPE_INT|CTLFLAG_RW,
 115     &tcp_rexmit_initial, 0, sysctl_msec_to_ticks, "I",
 116     "Initial Retransmission Timeout");
 117
 118 int     tcp_rexmit_min;
 119 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
 120     &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
 121     "Minimum Retransmission Timeout");
 122
 123 int     tcp_rexmit_slop;
 124 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
 125     &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
 126     "Retransmission Timer Slop");
 127
 128 VNET_DEFINE(int, tcp_always_keepalive) = 1;
 129 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_VNET|CTLFLAG_RW,
 130     &VNET_NAME(tcp_always_keepalive) , 0,
 131     "Assume SO_KEEPALIVE on all TCP connections");
 132
 133 int    tcp_fast_finwait2_recycle = 0;
 134 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
 135     &tcp_fast_finwait2_recycle, 0,
 136     "Recycle closed FIN_WAIT_2 connections faster");
 137
 138 int    tcp_finwait2_timeout;
 139 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW,
 140     &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout");
 141
 142 int     tcp_keepcnt = TCPTV_KEEPCNT;
 143 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
 144     "Number of keepalive probes to send");
 145
 146         /* max idle probes */
 147 int     tcp_maxpersistidle;
 148
 149 int     tcp_rexmit_drop_options = 0;
 150 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
 151     &tcp_rexmit_drop_options, 0,
 152     "Drop TCP options from 3rd and later retransmitted SYN");
 153
 154 VNET_DEFINE(int, tcp_pmtud_blackhole_detect);
 155 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection,
 156     CTLFLAG_RW|CTLFLAG_VNET,
 157     &VNET_NAME(tcp_pmtud_blackhole_detect), 0,
 158     "Path MTU Discovery Black Hole Detection Enabled");
 159
 160 #ifdef INET
 161 VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200;
 162 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss,
 163     CTLFLAG_RW|CTLFLAG_VNET,
 164     &VNET_NAME(tcp_pmtud_blackhole_mss), 0,
 165     "Path MTU Discovery Black Hole Detection lowered MSS");
 166 #endif
 167
 168 #ifdef INET6
 169 VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220;
 170 SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss,
 171     CTLFLAG_RW|CTLFLAG_VNET,
 172     &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0,
 173     "Path MTU Discovery IPv6 Black Hole Detection lowered MSS");
 174 #endif
 175
 176 #ifdef  RSS
 177 static int      per_cpu_timers = 1;
 178 #else
 179 static int      per_cpu_timers = 0;
 180 #endif
 181 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
 182     &per_cpu_timers , 0, "run tcp timers on all cpus");
 183
 184 /*
 185  * Map the given inp to a CPU id.
 186  *
 187  * This queries RSS if it's compiled in, else it defaults to the current
 188  * CPU ID.
 189  */
 190 inline int
 191 inp_to_cpuid(struct inpcb *inp)
 192 {
 193         u_int cpuid;
 194
 195 #ifdef  RSS
 196         if (per_cpu_timers) {
 197                 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
 198                 if (cpuid == NETISR_CPUID_NONE)
 199                         return (curcpu);        /* XXX */
 200                 else
 201                         return (cpuid);
 202         }
 203 #else
 204         /* Legacy, pre-RSS behaviour */
 205         if (per_cpu_timers) {
 206                 /*
 207                  * We don't have a flowid -> cpuid mapping, so cheat and
 208                  * just map unknown cpuids to curcpu.  Not the best, but
 209                  * apparently better than defaulting to swi 0.
 210                  */
 211                 cpuid = inp->inp_flowid % (mp_maxid + 1);
 212                 if (! CPU_ABSENT(cpuid))
 213                         return (cpuid);
 214                 return (curcpu);
 215         }
 216 #endif
 217         /* Default for RSS and non-RSS - cpuid 0 */
 218         else {
 219                 return (0);
 220         }
 221 }
 222
 223 /*
 224  * Tcp protocol timeout routine called every 500 ms.
 225  * Updates timestamps used for TCP
 226  * causes finite state machine actions if timers expire.
 227  */
 228 void
 229 tcp_slowtimo(void)
 230 {
 231         VNET_ITERATOR_DECL(vnet_iter);
 232
 233         VNET_LIST_RLOCK_NOSLEEP();
 234         VNET_FOREACH(vnet_iter) {
 235                 CURVNET_SET(vnet_iter);
 236                 (void) tcp_tw_2msl_scan(0);
 237                 CURVNET_RESTORE();
 238         }
 239         VNET_LIST_RUNLOCK_NOSLEEP();
 240 }
 241
 242 int     tcp_backoff[TCP_MAXRXTSHIFT + 1] =
 243     { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
 244
 245 int tcp_totbackoff = 2559;      /* sum of tcp_backoff[] */
 246
 247 /*
 248  * TCP timer processing.
 249  */
 250
 251 void
 252 tcp_timer_delack(void *xtp)
 253 {
 254         struct tcpcb *tp = xtp;
 255         struct inpcb *inp;
 256         CURVNET_SET(tp->t_vnet);
 257
 258         inp = tp->t_inpcb;
 259         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 260         INP_WLOCK(inp);
 261         if (callout_pending(&tp->t_timers->tt_delack) ||
 262             !callout_active(&tp->t_timers->tt_delack)) {
 263                 INP_WUNLOCK(inp);
 264                 CURVNET_RESTORE();
 265                 return;
 266         }
 267         callout_deactivate(&tp->t_timers->tt_delack);
 268         if ((inp->inp_flags & INP_DROPPED) != 0) {
 269                 INP_WUNLOCK(inp);
 270                 CURVNET_RESTORE();
 271                 return;
 272         }
 273         tp->t_flags |= TF_ACKNOW;
 274         TCPSTAT_INC(tcps_delack);
 275         (void) tp->t_fb->tfb_tcp_output(tp);
 276         INP_WUNLOCK(inp);
 277         CURVNET_RESTORE();
 278 }
 279
 280 void
 281 tcp_inpinfo_lock_del(struct inpcb *inp, struct tcpcb *tp)
 282 {
 283         if (inp && tp != NULL)
 284                 INP_WUNLOCK(inp);
 285 }
 286
 287 void
 288 tcp_timer_2msl(void *xtp)
 289 {
 290         struct tcpcb *tp = xtp;
 291         struct inpcb *inp;
 292         struct epoch_tracker et;
 293         CURVNET_SET(tp->t_vnet);
 294 #ifdef TCPDEBUG
 295         int ostate;
 296
 297         ostate = tp->t_state;
 298 #endif
 299         inp = tp->t_inpcb;
 300         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 301         INP_WLOCK(inp);
 302         tcp_free_sackholes(tp);
 303         if (callout_pending(&tp->t_timers->tt_2msl) ||
 304             !callout_active(&tp->t_timers->tt_2msl)) {
 305                 INP_WUNLOCK(tp->t_inpcb);
 306                 CURVNET_RESTORE();
 307                 return;
 308         }
 309         callout_deactivate(&tp->t_timers->tt_2msl);
 310         if ((inp->inp_flags & INP_DROPPED) != 0) {
 311                 INP_WUNLOCK(inp);
 312                 CURVNET_RESTORE();
 313                 return;
 314         }
 315         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 316                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 317         /*
 318          * 2 MSL timeout in shutdown went off.  If we're closed but
 319          * still waiting for peer to close and connection has been idle
 320          * too long delete connection control block.  Otherwise, check
 321          * again in a bit.
 322          *
 323          * If in TIME_WAIT state just ignore as this timeout is handled in
 324          * tcp_tw_2msl_scan().
 325          *
 326          * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
 327          * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
 328          * Ignore fact that there were recent incoming segments.
 329          */
 330         if ((inp->inp_flags & INP_TIMEWAIT) != 0) {
 331                 INP_WUNLOCK(inp);
 332                 CURVNET_RESTORE();
 333                 return;
 334         }
 335         if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
 336             tp->t_inpcb && tp->t_inpcb->inp_socket &&
 337             (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
 338                 TCPSTAT_INC(tcps_finwait2_drops);
 339                 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 340                         tcp_inpinfo_lock_del(inp, tp);
 341                         goto out;
 342                 }
 343                 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
 344                 tp = tcp_close(tp);
 345                 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
 346                 tcp_inpinfo_lock_del(inp, tp);
 347                 goto out;
 348         } else {
 349                 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) {
 350                         callout_reset(&tp->t_timers->tt_2msl,
 351                                       TP_KEEPINTVL(tp), tcp_timer_2msl, tp);
 352                 } else {
 353                         if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 354                                 tcp_inpinfo_lock_del(inp, tp);
 355                                 goto out;
 356                         }
 357                         INP_INFO_RLOCK_ET(&V_tcbinfo, et);
 358                         tp = tcp_close(tp);
 359                         INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
 360                         tcp_inpinfo_lock_del(inp, tp);
 361                         goto out;
 362                 }
 363         }
 364
 365 #ifdef TCPDEBUG
 366         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 367                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 368                           PRU_SLOWTIMO);
 369 #endif
 370         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 371
 372         if (tp != NULL)
 373                 INP_WUNLOCK(inp);
 374 out:
 375         CURVNET_RESTORE();
 376 }
 377
 378 void
 379 tcp_timer_keep(void *xtp)
 380 {
 381         struct tcpcb *tp = xtp;
 382         struct tcptemp *t_template;
 383         struct inpcb *inp;
 384         struct epoch_tracker et;
 385         CURVNET_SET(tp->t_vnet);
 386 #ifdef TCPDEBUG
 387         int ostate;
 388
 389         ostate = tp->t_state;
 390 #endif
 391         inp = tp->t_inpcb;
 392         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 393         INP_WLOCK(inp);
 394         if (callout_pending(&tp->t_timers->tt_keep) ||
 395             !callout_active(&tp->t_timers->tt_keep)) {
 396                 INP_WUNLOCK(inp);
 397                 CURVNET_RESTORE();
 398                 return;
 399         }
 400         callout_deactivate(&tp->t_timers->tt_keep);
 401         if ((inp->inp_flags & INP_DROPPED) != 0) {
 402                 INP_WUNLOCK(inp);
 403                 CURVNET_RESTORE();
 404                 return;
 405         }
 406         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 407                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 408
 409         /*
 410          * Because we don't regularly reset the keepalive callout in
 411          * the ESTABLISHED state, it may be that we don't actually need
 412          * to send a keepalive yet. If that occurs, schedule another
 413          * call for the next time the keepalive timer might expire.
 414          */
 415         if (TCPS_HAVEESTABLISHED(tp->t_state)) {
 416                 u_int idletime;
 417
 418                 idletime = ticks - tp->t_rcvtime;
 419                 if (idletime < TP_KEEPIDLE(tp)) {
 420                         callout_reset(&tp->t_timers->tt_keep,
 421                             TP_KEEPIDLE(tp) - idletime, tcp_timer_keep, tp);
 422                         INP_WUNLOCK(inp);
 423                         CURVNET_RESTORE();
 424                         return;
 425                 }
 426         }
 427
 428         /*
 429          * Keep-alive timer went off; send something
 430          * or drop connection if idle for too long.
 431          */
 432         TCPSTAT_INC(tcps_keeptimeo);
 433         if (tp->t_state < TCPS_ESTABLISHED)
 434                 goto dropit;
 435         if ((V_tcp_always_keepalive ||
 436             inp->inp_socket->so_options & SO_KEEPALIVE) &&
 437             tp->t_state <= TCPS_CLOSING) {
 438                 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
 439                         goto dropit;
 440                 /*
 441                  * Send a packet designed to force a response
 442                  * if the peer is up and reachable:
 443                  * either an ACK if the connection is still alive,
 444                  * or an RST if the peer has closed the connection
 445                  * due to timeout or reboot.
 446                  * Using sequence number tp->snd_una-1
 447                  * causes the transmitted zero-length segment
 448                  * to lie outside the receive window;
 449                  * by the protocol spec, this requires the
 450                  * correspondent TCP to respond.
 451                  */
 452                 TCPSTAT_INC(tcps_keepprobe);
 453                 t_template = tcpip_maketemplate(inp);
 454                 if (t_template) {
 455                         tcp_respond(tp, t_template->tt_ipgen,
 456                                     &t_template->tt_t, (struct mbuf *)NULL,
 457                                     tp->rcv_nxt, tp->snd_una - 1, 0);
 458                         free(t_template, M_TEMP);
 459                 }
 460                 callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
 461                               tcp_timer_keep, tp);
 462         } else
 463                 callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
 464                               tcp_timer_keep, tp);
 465
 466 #ifdef TCPDEBUG
 467         if (inp->inp_socket->so_options & SO_DEBUG)
 468                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 469                           PRU_SLOWTIMO);
 470 #endif
 471         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 472         INP_WUNLOCK(inp);
 473         CURVNET_RESTORE();
 474         return;
 475
 476 dropit:
 477         TCPSTAT_INC(tcps_keepdrops);
 478         if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 479                 tcp_inpinfo_lock_del(inp, tp);
 480                 goto out;
 481         }
 482         INP_INFO_RLOCK_ET(&V_tcbinfo, et);
 483         tp = tcp_drop(tp, ETIMEDOUT);
 484
 485 #ifdef TCPDEBUG
 486         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 487                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 488                           PRU_SLOWTIMO);
 489 #endif
 490         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 491         INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
 492         tcp_inpinfo_lock_del(inp, tp);
 493  out:
 494         CURVNET_RESTORE();
 495 }
 496
 497 void
 498 tcp_timer_persist(void *xtp)
 499 {
 500         struct tcpcb *tp = xtp;
 501         struct inpcb *inp;
 502         struct epoch_tracker et;
 503         CURVNET_SET(tp->t_vnet);
 504 #ifdef TCPDEBUG
 505         int ostate;
 506
 507         ostate = tp->t_state;
 508 #endif
 509         inp = tp->t_inpcb;
 510         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 511         INP_WLOCK(inp);
 512         if (callout_pending(&tp->t_timers->tt_persist) ||
 513             !callout_active(&tp->t_timers->tt_persist)) {
 514                 INP_WUNLOCK(inp);
 515                 CURVNET_RESTORE();
 516                 return;
 517         }
 518         callout_deactivate(&tp->t_timers->tt_persist);
 519         if ((inp->inp_flags & INP_DROPPED) != 0) {
 520                 INP_WUNLOCK(inp);
 521                 CURVNET_RESTORE();
 522                 return;
 523         }
 524         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 525                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 526         /*
 527          * Persistence timer into zero window.
 528          * Force a byte to be output, if possible.
 529          */
 530         TCPSTAT_INC(tcps_persisttimeo);
 531         /*
 532          * Hack: if the peer is dead/unreachable, we do not
 533          * time out if the window is closed.  After a full
 534          * backoff, drop the connection if the idle time
 535          * (no responses to probes) reaches the maximum
 536          * backoff that we would use if retransmitting.
 537          */
 538         if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
 539             (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
 540              ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
 541                 TCPSTAT_INC(tcps_persistdrop);
 542                 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 543                         tcp_inpinfo_lock_del(inp, tp);
 544                         goto out;
 545                 }
 546                 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
 547                 tp = tcp_drop(tp, ETIMEDOUT);
 548                 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
 549                 tcp_inpinfo_lock_del(inp, tp);
 550                 goto out;
 551         }
 552         /*
 553          * If the user has closed the socket then drop a persisting
 554          * connection after a much reduced timeout.
 555          */
 556         if (tp->t_state > TCPS_CLOSE_WAIT &&
 557             (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
 558                 TCPSTAT_INC(tcps_persistdrop);
 559                 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 560                         tcp_inpinfo_lock_del(inp, tp);
 561                         goto out;
 562                 }
 563                 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
 564                 tp = tcp_drop(tp, ETIMEDOUT);
 565                 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
 566                 tcp_inpinfo_lock_del(inp, tp);
 567                 goto out;
 568         }
 569         tcp_setpersist(tp);
 570         tp->t_flags |= TF_FORCEDATA;
 571         (void) tp->t_fb->tfb_tcp_output(tp);
 572         tp->t_flags &= ~TF_FORCEDATA;
 573
 574 #ifdef TCPDEBUG
 575         if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
 576                 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
 577 #endif
 578         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 579         INP_WUNLOCK(inp);
 580 out:
 581         CURVNET_RESTORE();
 582 }
 583
 584 void
 585 tcp_timer_rexmt(void * xtp)
 586 {
 587         struct tcpcb *tp = xtp;
 588         CURVNET_SET(tp->t_vnet);
 589         int rexmt;
 590         struct inpcb *inp;
 591         struct epoch_tracker et;
 592         bool isipv6;
 593 #ifdef TCPDEBUG
 594         int ostate;
 595
 596         ostate = tp->t_state;
 597 #endif
 598         inp = tp->t_inpcb;
 599         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 600         INP_WLOCK(inp);
 601         if (callout_pending(&tp->t_timers->tt_rexmt) ||
 602             !callout_active(&tp->t_timers->tt_rexmt)) {
 603                 INP_WUNLOCK(inp);
 604                 CURVNET_RESTORE();
 605                 return;
 606         }
 607         callout_deactivate(&tp->t_timers->tt_rexmt);
 608         if ((inp->inp_flags & INP_DROPPED) != 0) {
 609                 INP_WUNLOCK(inp);
 610                 CURVNET_RESTORE();
 611                 return;
 612         }
 613         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 614                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 615         tcp_free_sackholes(tp);
 616         TCP_LOG_EVENT(tp, NULL, NULL, NULL, TCP_LOG_RTO, 0, 0, NULL, false);
 617         if (tp->t_fb->tfb_tcp_rexmit_tmr) {
 618                 /* The stack has a timer action too. */
 619                 (*tp->t_fb->tfb_tcp_rexmit_tmr)(tp);
 620         }
 621         /*
 622          * Retransmission timer went off.  Message has not
 623          * been acked within retransmit interval.  Back off
 624          * to a longer retransmit interval and retransmit one segment.
 625          */
 626         if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
 627                 tp->t_rxtshift = TCP_MAXRXTSHIFT;
 628                 TCPSTAT_INC(tcps_timeoutdrop);
 629                 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 630                         tcp_inpinfo_lock_del(inp, tp);
 631                         goto out;
 632                 }
 633                 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
 634                 tp = tcp_drop(tp, ETIMEDOUT);
 635                 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
 636                 tcp_inpinfo_lock_del(inp, tp);
 637                 goto out;
 638         }
 639         if (tp->t_state == TCPS_SYN_SENT) {
 640                 /*
 641                  * If the SYN was retransmitted, indicate CWND to be
 642                  * limited to 1 segment in cc_conn_init().
 643                  */
 644                 tp->snd_cwnd = 1;
 645         } else if (tp->t_rxtshift == 1) {
 646                 /*
 647                  * first retransmit; record ssthresh and cwnd so they can
 648                  * be recovered if this turns out to be a "bad" retransmit.
 649                  * A retransmit is considered "bad" if an ACK for this
 650                  * segment is received within RTT/2 interval; the assumption
 651                  * here is that the ACK was already in flight.  See
 652                  * "On Estimating End-to-End Network Path Properties" by
 653                  * Allman and Paxson for more details.
 654                  */
 655                 tp->snd_cwnd_prev = tp->snd_cwnd;
 656                 tp->snd_ssthresh_prev = tp->snd_ssthresh;
 657                 tp->snd_recover_prev = tp->snd_recover;
 658                 if (IN_FASTRECOVERY(tp->t_flags))
 659                         tp->t_flags |= TF_WASFRECOVERY;
 660                 else
 661                         tp->t_flags &= ~TF_WASFRECOVERY;
 662                 if (IN_CONGRECOVERY(tp->t_flags))
 663                         tp->t_flags |= TF_WASCRECOVERY;
 664                 else
 665                         tp->t_flags &= ~TF_WASCRECOVERY;
 666                 if ((tp->t_flags & TF_RCVD_TSTMP) == 0)
 667                         tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
 668                 /* In the event that we've negotiated timestamps
 669                  * badrxtwin will be set to the value that we set
 670                  * the retransmitted packet's to_tsval to by tcp_output
 671                  */
 672                 tp->t_flags |= TF_PREVVALID;
 673         } else
 674                 tp->t_flags &= ~TF_PREVVALID;
 675         TCPSTAT_INC(tcps_rexmttimeo);
 676         if ((tp->t_state == TCPS_SYN_SENT) ||
 677             (tp->t_state == TCPS_SYN_RECEIVED))
 678                 rexmt = tcp_rexmit_initial * tcp_backoff[tp->t_rxtshift];
 679         else
 680                 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
 681         TCPT_RANGESET(tp->t_rxtcur, rexmt,
 682                       tp->t_rttmin, TCPTV_REXMTMAX);
 683
 684         /*
 685          * We enter the path for PLMTUD if connection is established or, if
 686          * connection is FIN_WAIT_1 status, reason for the last is that if
 687          * amount of data we send is very small, we could send it in couple of
 688          * packets and process straight to FIN. In that case we won't catch
 689          * ESTABLISHED state.
 690          */
 691 #ifdef INET6
 692         isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? true : false;
 693 #else
 694         isipv6 = false;
 695 #endif
 696         if (((V_tcp_pmtud_blackhole_detect == 1) ||
 697             (V_tcp_pmtud_blackhole_detect == 2 && !isipv6) ||
 698             (V_tcp_pmtud_blackhole_detect == 3 && isipv6)) &&
 699             ((tp->t_state == TCPS_ESTABLISHED) ||
 700             (tp->t_state == TCPS_FIN_WAIT_1))) {
 701                 if (tp->t_rxtshift == 1) {
 702                         /*
 703                          * We enter blackhole detection after the first
 704                          * unsuccessful timer based retransmission.
 705                          * Then we reduce up to two times the MSS, each
 706                          * candidate giving two tries of retransmissions.
 707                          * But we give a candidate only two tries, if it
 708                          * actually reduces the MSS.
 709                          */
 710                         tp->t_blackhole_enter = 2;
 711                         tp->t_blackhole_exit = tp->t_blackhole_enter;
 712                         if (isipv6) {
 713 #ifdef INET6
 714                                 if (tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss)
 715                                         tp->t_blackhole_exit += 2;
 716                                 if (tp->t_maxseg > V_tcp_v6mssdflt &&
 717                                     V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt)
 718                                         tp->t_blackhole_exit += 2;
 719 #endif
 720                         } else {
 721 #ifdef INET
 722                                 if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss)
 723                                         tp->t_blackhole_exit += 2;
 724                                 if (tp->t_maxseg > V_tcp_mssdflt &&
 725                                     V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt)
 726                                         tp->t_blackhole_exit += 2;
 727 #endif
 728                         }
 729                 }
 730                 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
 731                     (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
 732                     (tp->t_rxtshift >= tp->t_blackhole_enter &&
 733                     tp->t_rxtshift < tp->t_blackhole_exit &&
 734                     (tp->t_rxtshift - tp->t_blackhole_enter) % 2 == 0)) {
 735                         /*
 736                          * Enter Path MTU Black-hole Detection mechanism:
 737                          * - Disable Path MTU Discovery (IP "DF" bit).
 738                          * - Reduce MTU to lower value than what we
 739                          *   negotiated with peer.
 740                          */
 741                         if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) == 0) {
 742                                 /* Record that we may have found a black hole. */
 743                                 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
 744                                 /* Keep track of previous MSS. */
 745                                 tp->t_pmtud_saved_maxseg = tp->t_maxseg;
 746                         }
 747
 748                         /*
 749                          * Reduce the MSS to blackhole value or to the default
 750                          * in an attempt to retransmit.
 751                          */
 752 #ifdef INET6
 753                         if (isipv6 &&
 754                             tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss &&
 755                             V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt) {
 756                                 /* Use the sysctl tuneable blackhole MSS. */
 757                                 tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss;
 758                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
 759                         } else if (isipv6) {
 760                                 /* Use the default MSS. */
 761                                 tp->t_maxseg = V_tcp_v6mssdflt;
 762                                 /*
 763                                  * Disable Path MTU Discovery when we switch to
 764                                  * minmss.
 765                                  */
 766                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 767                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
 768                         }
 769 #endif
 770 #if defined(INET6) && defined(INET)
 771                         else
 772 #endif
 773 #ifdef INET
 774                         if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss &&
 775                             V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt) {
 776                                 /* Use the sysctl tuneable blackhole MSS. */
 777                                 tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
 778                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
 779                         } else {
 780                                 /* Use the default MSS. */
 781                                 tp->t_maxseg = V_tcp_mssdflt;
 782                                 /*
 783                                  * Disable Path MTU Discovery when we switch to
 784                                  * minmss.
 785                                  */
 786                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 787                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
 788                         }
 789 #endif
 790                         /*
 791                          * Reset the slow-start flight size
 792                          * as it may depend on the new MSS.
 793                          */
 794                         if (CC_ALGO(tp)->conn_init != NULL)
 795                                 CC_ALGO(tp)->conn_init(tp->ccv);
 796                 } else {
 797                         /*
 798                          * If further retransmissions are still unsuccessful
 799                          * with a lowered MTU, maybe this isn't a blackhole and
 800                          * we restore the previous MSS and blackhole detection
 801                          * flags.
 802                          */
 803                         if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
 804                             (tp->t_rxtshift >= tp->t_blackhole_exit)) {
 805                                 tp->t_flags2 |= TF2_PLPMTU_PMTUD;
 806                                 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
 807                                 tp->t_maxseg = tp->t_pmtud_saved_maxseg;
 808                                 TCPSTAT_INC(tcps_pmtud_blackhole_failed);
 809                                 /*
 810                                  * Reset the slow-start flight size as it
 811                                  * may depend on the new MSS.
 812                                  */
 813                                 if (CC_ALGO(tp)->conn_init != NULL)
 814                                         CC_ALGO(tp)->conn_init(tp->ccv);
 815                         }
 816                 }
 817         }
 818
 819         /*
 820          * Disable RFC1323 and SACK if we haven't got any response to
 821          * our third SYN to work-around some broken terminal servers
 822          * (most of which have hopefully been retired) that have bad VJ
 823          * header compression code which trashes TCP segments containing
 824          * unknown-to-them TCP options.
 825          */
 826         if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
 827             (tp->t_rxtshift == 3))
 828                 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
 829         /*
 830          * If we backed off this far, notify the L3 protocol that we're having
 831          * connection problems.
 832          */
 833         if (tp->t_rxtshift > TCP_RTT_INVALIDATE) {
 834 #ifdef INET6
 835                 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
 836                         in6_losing(tp->t_inpcb);
 837                 else
 838 #endif
 839                         in_losing(tp->t_inpcb);
 840         }
 841         tp->snd_nxt = tp->snd_una;
 842         tp->snd_recover = tp->snd_max;
 843         /*
 844          * Force a segment to be sent.
 845          */
 846         tp->t_flags |= TF_ACKNOW;
 847         /*
 848          * If timing a segment in this window, stop the timer.
 849          */
 850         tp->t_rtttime = 0;
 851
 852         cc_cong_signal(tp, NULL, CC_RTO);
 853
 854         (void) tp->t_fb->tfb_tcp_output(tp);
 855
 856 #ifdef TCPDEBUG
 857         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 858                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 859                           PRU_SLOWTIMO);
 860 #endif
 861         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 862         INP_WUNLOCK(inp);
 863 out:
 864         CURVNET_RESTORE();
 865 }
 866
 867 void
 868 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
 869 {
 870         struct callout *t_callout;
 871         timeout_t *f_callout;
 872         struct inpcb *inp = tp->t_inpcb;
 873         int cpu = inp_to_cpuid(inp);
 874
 875 #ifdef TCP_OFFLOAD
 876         if (tp->t_flags & TF_TOE)
 877                 return;
 878 #endif
 879
 880         if (tp->t_timers->tt_flags & TT_STOPPED)
 881                 return;
 882
 883         switch (timer_type) {
 884                 case TT_DELACK:
 885                         t_callout = &tp->t_timers->tt_delack;
 886                         f_callout = tcp_timer_delack;
 887                         break;
 888                 case TT_REXMT:
 889                         t_callout = &tp->t_timers->tt_rexmt;
 890                         f_callout = tcp_timer_rexmt;
 891                         break;
 892                 case TT_PERSIST:
 893                         t_callout = &tp->t_timers->tt_persist;
 894                         f_callout = tcp_timer_persist;
 895                         break;
 896                 case TT_KEEP:
 897                         t_callout = &tp->t_timers->tt_keep;
 898                         f_callout = tcp_timer_keep;
 899                         break;
 900                 case TT_2MSL:
 901                         t_callout = &tp->t_timers->tt_2msl;
 902                         f_callout = tcp_timer_2msl;
 903                         break;
 904                 default:
 905                         if (tp->t_fb->tfb_tcp_timer_activate) {
 906                                 tp->t_fb->tfb_tcp_timer_activate(tp, timer_type, delta);
 907                                 return;
 908                         }
 909                         panic("tp %p bad timer_type %#x", tp, timer_type);
 910                 }
 911         if (delta == 0) {
 912                 callout_stop(t_callout);
 913         } else {
 914                 callout_reset_on(t_callout, delta, f_callout, tp, cpu);
 915         }
 916 }
 917
 918 int
 919 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type)
 920 {
 921         struct callout *t_callout;
 922
 923         switch (timer_type) {
 924                 case TT_DELACK:
 925                         t_callout = &tp->t_timers->tt_delack;
 926                         break;
 927                 case TT_REXMT:
 928                         t_callout = &tp->t_timers->tt_rexmt;
 929                         break;
 930                 case TT_PERSIST:
 931                         t_callout = &tp->t_timers->tt_persist;
 932                         break;
 933                 case TT_KEEP:
 934                         t_callout = &tp->t_timers->tt_keep;
 935                         break;
 936                 case TT_2MSL:
 937                         t_callout = &tp->t_timers->tt_2msl;
 938                         break;
 939                 default:
 940                         if (tp->t_fb->tfb_tcp_timer_active) {
 941                                 return(tp->t_fb->tfb_tcp_timer_active(tp, timer_type));
 942                         }
 943                         panic("tp %p bad timer_type %#x", tp, timer_type);
 944                 }
 945         return callout_active(t_callout);
 946 }
 947
 948 /*
 949  * Stop the timer from running, and apply a flag
 950  * against the timer_flags that will force the
 951  * timer never to run. The flag is needed to assure
 952  * a race does not leave it running and cause
 953  * the timer to possibly restart itself (keep and persist
 954  * especially do this).
 955  */
 956 int
 957 tcp_timer_suspend(struct tcpcb *tp, uint32_t timer_type)
 958 {
 959         struct callout *t_callout;
 960         uint32_t t_flags;
 961
 962         switch (timer_type) {
 963                 case TT_DELACK:
 964                         t_flags = TT_DELACK_SUS;
 965                         t_callout = &tp->t_timers->tt_delack;
 966                         break;
 967                 case TT_REXMT:
 968                         t_flags = TT_REXMT_SUS;
 969                         t_callout = &tp->t_timers->tt_rexmt;
 970                         break;
 971                 case TT_PERSIST:
 972                         t_flags = TT_PERSIST_SUS;
 973                         t_callout = &tp->t_timers->tt_persist;
 974                         break;
 975                 case TT_KEEP:
 976                         t_flags = TT_KEEP_SUS;
 977                         t_callout = &tp->t_timers->tt_keep;
 978                         break;
 979                 case TT_2MSL:
 980                         t_flags = TT_2MSL_SUS;
 981                         t_callout = &tp->t_timers->tt_2msl;
 982                         break;
 983                 default:
 984                         panic("tp:%p bad timer_type 0x%x", tp, timer_type);
 985         }
 986         tp->t_timers->tt_flags |= t_flags;
 987         return (callout_stop(t_callout));
 988 }
 989
 990 void
 991 tcp_timers_unsuspend(struct tcpcb *tp, uint32_t timer_type)
 992 {
 993         switch (timer_type) {
 994                 case TT_DELACK:
 995                         if (tp->t_timers->tt_flags & TT_DELACK_SUS) {
 996                                 tp->t_timers->tt_flags &= ~TT_DELACK_SUS;
 997                                 if (tp->t_flags & TF_DELACK) {
 998                                         /* Delayed ack timer should be up activate a timer */
 999                                         tp->t_flags &= ~TF_DELACK;
1000                                         tcp_timer_activate(tp, TT_DELACK,
1001                                             tcp_delacktime);
1002                                 }
1003                         }
1004                         break;
1005                 case TT_REXMT:
1006                         if (tp->t_timers->tt_flags & TT_REXMT_SUS) {
1007                                 tp->t_timers->tt_flags &= ~TT_REXMT_SUS;
1008                                 if (SEQ_GT(tp->snd_max, tp->snd_una) &&
1009                                     (tcp_timer_active((tp), TT_PERSIST) == 0) &&
1010                                     tp->snd_wnd) {
1011                                         /* We have outstanding data activate a timer */
1012                                         tcp_timer_activate(tp, TT_REXMT,
1013                                             tp->t_rxtcur);
1014                                 }
1015                         }
1016                         break;
1017                 case TT_PERSIST:
1018                         if (tp->t_timers->tt_flags & TT_PERSIST_SUS) {
1019                                 tp->t_timers->tt_flags &= ~TT_PERSIST_SUS;
1020                                 if (tp->snd_wnd == 0) {
1021                                         /* Activate the persists timer */
1022                                         tp->t_rxtshift = 0;
1023                                         tcp_setpersist(tp);
1024                                 }
1025                         }
1026                         break;
1027                 case TT_KEEP:
1028                         if (tp->t_timers->tt_flags & TT_KEEP_SUS) {
1029                                 tp->t_timers->tt_flags &= ~TT_KEEP_SUS;
1030                                 tcp_timer_activate(tp, TT_KEEP,
1031                                             TCPS_HAVEESTABLISHED(tp->t_state) ?
1032                                             TP_KEEPIDLE(tp) : TP_KEEPINIT(tp));
1033                         }
1034                         break;
1035                 case TT_2MSL:
1036                         if (tp->t_timers->tt_flags &= TT_2MSL_SUS) {
1037                                 tp->t_timers->tt_flags &= ~TT_2MSL_SUS;
1038                                 if ((tp->t_state == TCPS_FIN_WAIT_2) &&
1039                                     ((tp->t_inpcb->inp_socket == NULL) ||
1040                                      (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE))) {
1041                                         /* Star the 2MSL timer */
1042                                         tcp_timer_activate(tp, TT_2MSL,
1043                                             (tcp_fast_finwait2_recycle) ?
1044                                             tcp_finwait2_timeout : TP_MAXIDLE(tp));
1045                                 }
1046                         }
1047                         break;
1048                 default:
1049                         panic("tp:%p bad timer_type 0x%x", tp, timer_type);
1050         }
1051 }
1052
1053 void
1054 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
1055 {
1056         struct callout *t_callout;
1057
1058         tp->t_timers->tt_flags |= TT_STOPPED;
1059         switch (timer_type) {
1060                 case TT_DELACK:
1061                         t_callout = &tp->t_timers->tt_delack;
1062                         break;
1063                 case TT_REXMT:
1064                         t_callout = &tp->t_timers->tt_rexmt;
1065                         break;
1066                 case TT_PERSIST:
1067                         t_callout = &tp->t_timers->tt_persist;
1068                         break;
1069                 case TT_KEEP:
1070                         t_callout = &tp->t_timers->tt_keep;
1071                         break;
1072                 case TT_2MSL:
1073                         t_callout = &tp->t_timers->tt_2msl;
1074                         break;
1075                 default:
1076                         if (tp->t_fb->tfb_tcp_timer_stop) {
1077                                 /*
1078                                  * XXXrrs we need to look at this with the
1079                                  * stop case below (flags).
1080                                  */
1081                                 tp->t_fb->tfb_tcp_timer_stop(tp, timer_type);
1082                                 return;
1083                         }
1084                         panic("tp %p bad timer_type %#x", tp, timer_type);
1085                 }
1086
1087         if (callout_async_drain(t_callout, tcp_timer_discard) == 0) {
1088                 /*
1089                  * Can't stop the callout, defer tcpcb actual deletion
1090                  * to the last one. We do this using the async drain
1091                  * function and incrementing the count in
1092                  */
1093                 tp->t_timers->tt_draincnt++;
1094         }
1095 }