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,
  86     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
  87     &tcp_persmin, 0, sysctl_msec_to_ticks, "I",
  88     "minimum persistence interval");
  89
  90 int    tcp_persmax;
  91 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmax,
  92     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
  93     &tcp_persmax, 0, sysctl_msec_to_ticks, "I",
  94     "maximum persistence interval");
  95
  96 int     tcp_keepinit;
  97 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit,
  98     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
  99     &tcp_keepinit, 0, sysctl_msec_to_ticks, "I",
 100     "time to establish connection");
 101
 102 int     tcp_keepidle;
 103 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle,
 104     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 105     &tcp_keepidle, 0, sysctl_msec_to_ticks, "I",
 106     "time before keepalive probes begin");
 107
 108 int     tcp_keepintvl;
 109 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl,
 110     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 111     &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I",
 112     "time between keepalive probes");
 113
 114 int     tcp_delacktime;
 115 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime,
 116     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 117     &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
 118     "Time before a delayed ACK is sent");
 119
 120 VNET_DEFINE(int, tcp_msl);
 121 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl,
 122     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_VNET,
 123     &VNET_NAME(tcp_msl), 0, sysctl_msec_to_ticks, "I",
 124     "Maximum segment lifetime");
 125
 126 int     tcp_rexmit_initial;
 127 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_initial,
 128    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 129     &tcp_rexmit_initial, 0, sysctl_msec_to_ticks, "I",
 130     "Initial Retransmission Timeout");
 131
 132 int     tcp_rexmit_min;
 133 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min,
 134     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 135     &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
 136     "Minimum Retransmission Timeout");
 137
 138 int     tcp_rexmit_slop;
 139 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop,
 140     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 141     &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
 142     "Retransmission Timer Slop");
 143
 144 VNET_DEFINE(int, tcp_always_keepalive) = 1;
 145 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_VNET|CTLFLAG_RW,
 146     &VNET_NAME(tcp_always_keepalive) , 0,
 147     "Assume SO_KEEPALIVE on all TCP connections");
 148
 149 int    tcp_fast_finwait2_recycle = 0;
 150 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
 151     &tcp_fast_finwait2_recycle, 0,
 152     "Recycle closed FIN_WAIT_2 connections faster");
 153
 154 int    tcp_finwait2_timeout;
 155 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout,
 156     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 157     &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I",
 158     "FIN-WAIT2 timeout");
 159
 160 int     tcp_keepcnt = TCPTV_KEEPCNT;
 161 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
 162     "Number of keepalive probes to send");
 163
 164         /* max idle probes */
 165 int     tcp_maxpersistidle;
 166
 167 int     tcp_rexmit_drop_options = 0;
 168 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
 169     &tcp_rexmit_drop_options, 0,
 170     "Drop TCP options from 3rd and later retransmitted SYN");
 171
 172 VNET_DEFINE(int, tcp_pmtud_blackhole_detect);
 173 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection,
 174     CTLFLAG_RW|CTLFLAG_VNET,
 175     &VNET_NAME(tcp_pmtud_blackhole_detect), 0,
 176     "Path MTU Discovery Black Hole Detection Enabled");
 177
 178 #ifdef INET
 179 VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200;
 180 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss,
 181     CTLFLAG_RW|CTLFLAG_VNET,
 182     &VNET_NAME(tcp_pmtud_blackhole_mss), 0,
 183     "Path MTU Discovery Black Hole Detection lowered MSS");
 184 #endif
 185
 186 #ifdef INET6
 187 VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220;
 188 SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss,
 189     CTLFLAG_RW|CTLFLAG_VNET,
 190     &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0,
 191     "Path MTU Discovery IPv6 Black Hole Detection lowered MSS");
 192 #endif
 193
 194 #ifdef  RSS
 195 static int      per_cpu_timers = 1;
 196 #else
 197 static int      per_cpu_timers = 0;
 198 #endif
 199 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
 200     &per_cpu_timers , 0, "run tcp timers on all cpus");
 201
 202 /*
 203  * Map the given inp to a CPU id.
 204  *
 205  * This queries RSS if it's compiled in, else it defaults to the current
 206  * CPU ID.
 207  */
 208 inline int
 209 inp_to_cpuid(struct inpcb *inp)
 210 {
 211         u_int cpuid;
 212
 213         if (per_cpu_timers) {
 214 #ifdef  RSS
 215                 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
 216                 if (cpuid == NETISR_CPUID_NONE)
 217                         return (curcpu);        /* XXX */
 218                 else
 219                         return (cpuid);
 220 #endif
 221                 /*
 222                  * We don't have a flowid -> cpuid mapping, so cheat and
 223                  * just map unknown cpuids to curcpu.  Not the best, but
 224                  * apparently better than defaulting to swi 0.
 225                  */
 226                 cpuid = inp->inp_flowid % (mp_maxid + 1);
 227                 if (! CPU_ABSENT(cpuid))
 228                         return (cpuid);
 229                 return (curcpu);
 230         } else {
 231                 return (0);
 232         }
 233 }
 234
 235 /*
 236  * Tcp protocol timeout routine called every 500 ms.
 237  * Updates timestamps used for TCP
 238  * causes finite state machine actions if timers expire.
 239  */
 240 void
 241 tcp_slowtimo(void)
 242 {
 243         VNET_ITERATOR_DECL(vnet_iter);
 244
 245         VNET_LIST_RLOCK_NOSLEEP();
 246         VNET_FOREACH(vnet_iter) {
 247                 CURVNET_SET(vnet_iter);
 248                 (void) tcp_tw_2msl_scan(0);
 249                 CURVNET_RESTORE();
 250         }
 251         VNET_LIST_RUNLOCK_NOSLEEP();
 252 }
 253
 254 int     tcp_backoff[TCP_MAXRXTSHIFT + 1] =
 255     { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
 256
 257 int tcp_totbackoff = 2559;      /* sum of tcp_backoff[] */
 258
 259 /*
 260  * TCP timer processing.
 261  */
 262
 263 void
 264 tcp_timer_delack(void *xtp)
 265 {
 266         struct epoch_tracker et;
 267         struct tcpcb *tp = xtp;
 268         struct inpcb *inp;
 269         CURVNET_SET(tp->t_vnet);
 270
 271         inp = tp->t_inpcb;
 272         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 273         INP_WLOCK(inp);
 274         if (callout_pending(&tp->t_timers->tt_delack) ||
 275             !callout_active(&tp->t_timers->tt_delack)) {
 276                 INP_WUNLOCK(inp);
 277                 CURVNET_RESTORE();
 278                 return;
 279         }
 280         callout_deactivate(&tp->t_timers->tt_delack);
 281         if ((inp->inp_flags & INP_DROPPED) != 0) {
 282                 INP_WUNLOCK(inp);
 283                 CURVNET_RESTORE();
 284                 return;
 285         }
 286         tp->t_flags |= TF_ACKNOW;
 287         TCPSTAT_INC(tcps_delack);
 288         NET_EPOCH_ENTER(et);
 289         (void) tp->t_fb->tfb_tcp_output(tp);
 290         INP_WUNLOCK(inp);
 291         NET_EPOCH_EXIT(et);
 292         CURVNET_RESTORE();
 293 }
 294
 295 void
 296 tcp_inpinfo_lock_del(struct inpcb *inp, struct tcpcb *tp)
 297 {
 298         if (inp && tp != NULL)
 299                 INP_WUNLOCK(inp);
 300 }
 301
 302 void
 303 tcp_timer_2msl(void *xtp)
 304 {
 305         struct tcpcb *tp = xtp;
 306         struct inpcb *inp;
 307         struct epoch_tracker et;
 308         CURVNET_SET(tp->t_vnet);
 309 #ifdef TCPDEBUG
 310         int ostate;
 311
 312         ostate = tp->t_state;
 313 #endif
 314         inp = tp->t_inpcb;
 315         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 316         INP_WLOCK(inp);
 317         tcp_free_sackholes(tp);
 318         if (callout_pending(&tp->t_timers->tt_2msl) ||
 319             !callout_active(&tp->t_timers->tt_2msl)) {
 320                 INP_WUNLOCK(tp->t_inpcb);
 321                 CURVNET_RESTORE();
 322                 return;
 323         }
 324         callout_deactivate(&tp->t_timers->tt_2msl);
 325         if ((inp->inp_flags & INP_DROPPED) != 0) {
 326                 INP_WUNLOCK(inp);
 327                 CURVNET_RESTORE();
 328                 return;
 329         }
 330         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 331                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 332         /*
 333          * 2 MSL timeout in shutdown went off.  If we're closed but
 334          * still waiting for peer to close and connection has been idle
 335          * too long delete connection control block.  Otherwise, check
 336          * again in a bit.
 337          *
 338          * If in TIME_WAIT state just ignore as this timeout is handled in
 339          * tcp_tw_2msl_scan().
 340          *
 341          * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
 342          * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
 343          * Ignore fact that there were recent incoming segments.
 344          */
 345         if ((inp->inp_flags & INP_TIMEWAIT) != 0) {
 346                 INP_WUNLOCK(inp);
 347                 CURVNET_RESTORE();
 348                 return;
 349         }
 350         if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
 351             tp->t_inpcb && tp->t_inpcb->inp_socket &&
 352             (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
 353                 TCPSTAT_INC(tcps_finwait2_drops);
 354                 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 355                         tcp_inpinfo_lock_del(inp, tp);
 356                         goto out;
 357                 }
 358                 NET_EPOCH_ENTER(et);
 359                 tp = tcp_close(tp);
 360                 NET_EPOCH_EXIT(et);
 361                 tcp_inpinfo_lock_del(inp, tp);
 362                 goto out;
 363         } else {
 364                 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) {
 365                         callout_reset(&tp->t_timers->tt_2msl,
 366                                       TP_KEEPINTVL(tp), tcp_timer_2msl, tp);
 367                 } else {
 368                         if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 369                                 tcp_inpinfo_lock_del(inp, tp);
 370                                 goto out;
 371                         }
 372                         NET_EPOCH_ENTER(et);
 373                         tp = tcp_close(tp);
 374                         NET_EPOCH_EXIT(et);
 375                         tcp_inpinfo_lock_del(inp, tp);
 376                         goto out;
 377                 }
 378         }
 379
 380 #ifdef TCPDEBUG
 381         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 382                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 383                           PRU_SLOWTIMO);
 384 #endif
 385         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 386
 387         if (tp != NULL)
 388                 INP_WUNLOCK(inp);
 389 out:
 390         CURVNET_RESTORE();
 391 }
 392
 393 void
 394 tcp_timer_keep(void *xtp)
 395 {
 396         struct tcpcb *tp = xtp;
 397         struct tcptemp *t_template;
 398         struct inpcb *inp;
 399         struct epoch_tracker et;
 400         CURVNET_SET(tp->t_vnet);
 401 #ifdef TCPDEBUG
 402         int ostate;
 403
 404         ostate = tp->t_state;
 405 #endif
 406         inp = tp->t_inpcb;
 407         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 408         INP_WLOCK(inp);
 409         if (callout_pending(&tp->t_timers->tt_keep) ||
 410             !callout_active(&tp->t_timers->tt_keep)) {
 411                 INP_WUNLOCK(inp);
 412                 CURVNET_RESTORE();
 413                 return;
 414         }
 415         callout_deactivate(&tp->t_timers->tt_keep);
 416         if ((inp->inp_flags & INP_DROPPED) != 0) {
 417                 INP_WUNLOCK(inp);
 418                 CURVNET_RESTORE();
 419                 return;
 420         }
 421         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 422                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 423
 424         /*
 425          * Because we don't regularly reset the keepalive callout in
 426          * the ESTABLISHED state, it may be that we don't actually need
 427          * to send a keepalive yet. If that occurs, schedule another
 428          * call for the next time the keepalive timer might expire.
 429          */
 430         if (TCPS_HAVEESTABLISHED(tp->t_state)) {
 431                 u_int idletime;
 432
 433                 idletime = ticks - tp->t_rcvtime;
 434                 if (idletime < TP_KEEPIDLE(tp)) {
 435                         callout_reset(&tp->t_timers->tt_keep,
 436                             TP_KEEPIDLE(tp) - idletime, tcp_timer_keep, tp);
 437                         INP_WUNLOCK(inp);
 438                         CURVNET_RESTORE();
 439                         return;
 440                 }
 441         }
 442
 443         /*
 444          * Keep-alive timer went off; send something
 445          * or drop connection if idle for too long.
 446          */
 447         TCPSTAT_INC(tcps_keeptimeo);
 448         if (tp->t_state < TCPS_ESTABLISHED)
 449                 goto dropit;
 450         if ((V_tcp_always_keepalive ||
 451             inp->inp_socket->so_options & SO_KEEPALIVE) &&
 452             tp->t_state <= TCPS_CLOSING) {
 453                 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
 454                         goto dropit;
 455                 /*
 456                  * Send a packet designed to force a response
 457                  * if the peer is up and reachable:
 458                  * either an ACK if the connection is still alive,
 459                  * or an RST if the peer has closed the connection
 460                  * due to timeout or reboot.
 461                  * Using sequence number tp->snd_una-1
 462                  * causes the transmitted zero-length segment
 463                  * to lie outside the receive window;
 464                  * by the protocol spec, this requires the
 465                  * correspondent TCP to respond.
 466                  */
 467                 TCPSTAT_INC(tcps_keepprobe);
 468                 t_template = tcpip_maketemplate(inp);
 469                 if (t_template) {
 470                         NET_EPOCH_ENTER(et);
 471                         tcp_respond(tp, t_template->tt_ipgen,
 472                                     &t_template->tt_t, (struct mbuf *)NULL,
 473                                     tp->rcv_nxt, tp->snd_una - 1, 0);
 474                         NET_EPOCH_EXIT(et);
 475                         free(t_template, M_TEMP);
 476                 }
 477                 callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
 478                               tcp_timer_keep, tp);
 479         } else
 480                 callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
 481                               tcp_timer_keep, tp);
 482
 483 #ifdef TCPDEBUG
 484         if (inp->inp_socket->so_options & SO_DEBUG)
 485                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 486                           PRU_SLOWTIMO);
 487 #endif
 488         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 489         INP_WUNLOCK(inp);
 490         CURVNET_RESTORE();
 491         return;
 492
 493 dropit:
 494         TCPSTAT_INC(tcps_keepdrops);
 495         if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 496                 tcp_inpinfo_lock_del(inp, tp);
 497                 goto out;
 498         }
 499         NET_EPOCH_ENTER(et);
 500         tp = tcp_drop(tp, ETIMEDOUT);
 501
 502 #ifdef TCPDEBUG
 503         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 504                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 505                           PRU_SLOWTIMO);
 506 #endif
 507         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 508         NET_EPOCH_EXIT(et);
 509         tcp_inpinfo_lock_del(inp, tp);
 510  out:
 511         CURVNET_RESTORE();
 512 }
 513
 514 void
 515 tcp_timer_persist(void *xtp)
 516 {
 517         struct tcpcb *tp = xtp;
 518         struct inpcb *inp;
 519         struct epoch_tracker et;
 520         CURVNET_SET(tp->t_vnet);
 521 #ifdef TCPDEBUG
 522         int ostate;
 523
 524         ostate = tp->t_state;
 525 #endif
 526         inp = tp->t_inpcb;
 527         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 528         INP_WLOCK(inp);
 529         if (callout_pending(&tp->t_timers->tt_persist) ||
 530             !callout_active(&tp->t_timers->tt_persist)) {
 531                 INP_WUNLOCK(inp);
 532                 CURVNET_RESTORE();
 533                 return;
 534         }
 535         callout_deactivate(&tp->t_timers->tt_persist);
 536         if ((inp->inp_flags & INP_DROPPED) != 0) {
 537                 INP_WUNLOCK(inp);
 538                 CURVNET_RESTORE();
 539                 return;
 540         }
 541         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 542                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 543         /*
 544          * Persistence timer into zero window.
 545          * Force a byte to be output, if possible.
 546          */
 547         TCPSTAT_INC(tcps_persisttimeo);
 548         /*
 549          * Hack: if the peer is dead/unreachable, we do not
 550          * time out if the window is closed.  After a full
 551          * backoff, drop the connection if the idle time
 552          * (no responses to probes) reaches the maximum
 553          * backoff that we would use if retransmitting.
 554          */
 555         if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
 556             (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
 557              ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
 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                 NET_EPOCH_ENTER(et);
 564                 tp = tcp_drop(tp, ETIMEDOUT);
 565                 NET_EPOCH_EXIT(et);
 566                 tcp_inpinfo_lock_del(inp, tp);
 567                 goto out;
 568         }
 569         /*
 570          * If the user has closed the socket then drop a persisting
 571          * connection after a much reduced timeout.
 572          */
 573         if (tp->t_state > TCPS_CLOSE_WAIT &&
 574             (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
 575                 TCPSTAT_INC(tcps_persistdrop);
 576                 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 577                         tcp_inpinfo_lock_del(inp, tp);
 578                         goto out;
 579                 }
 580                 NET_EPOCH_ENTER(et);
 581                 tp = tcp_drop(tp, ETIMEDOUT);
 582                 NET_EPOCH_EXIT(et);
 583                 tcp_inpinfo_lock_del(inp, tp);
 584                 goto out;
 585         }
 586         tcp_setpersist(tp);
 587         tp->t_flags |= TF_FORCEDATA;
 588         NET_EPOCH_ENTER(et);
 589         (void) tp->t_fb->tfb_tcp_output(tp);
 590         NET_EPOCH_EXIT(et);
 591         tp->t_flags &= ~TF_FORCEDATA;
 592
 593 #ifdef TCPDEBUG
 594         if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
 595                 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
 596 #endif
 597         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 598         INP_WUNLOCK(inp);
 599 out:
 600         CURVNET_RESTORE();
 601 }
 602
 603 void
 604 tcp_timer_rexmt(void * xtp)
 605 {
 606         struct tcpcb *tp = xtp;
 607         CURVNET_SET(tp->t_vnet);
 608         int rexmt;
 609         struct inpcb *inp;
 610         struct epoch_tracker et;
 611         bool isipv6;
 612 #ifdef TCPDEBUG
 613         int ostate;
 614
 615         ostate = tp->t_state;
 616 #endif
 617         inp = tp->t_inpcb;
 618         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 619         INP_WLOCK(inp);
 620         if (callout_pending(&tp->t_timers->tt_rexmt) ||
 621             !callout_active(&tp->t_timers->tt_rexmt)) {
 622                 INP_WUNLOCK(inp);
 623                 CURVNET_RESTORE();
 624                 return;
 625         }
 626         callout_deactivate(&tp->t_timers->tt_rexmt);
 627         if ((inp->inp_flags & INP_DROPPED) != 0) {
 628                 INP_WUNLOCK(inp);
 629                 CURVNET_RESTORE();
 630                 return;
 631         }
 632         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 633                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 634         tcp_free_sackholes(tp);
 635         TCP_LOG_EVENT(tp, NULL, NULL, NULL, TCP_LOG_RTO, 0, 0, NULL, false);
 636         if (tp->t_fb->tfb_tcp_rexmit_tmr) {
 637                 /* The stack has a timer action too. */
 638                 (*tp->t_fb->tfb_tcp_rexmit_tmr)(tp);
 639         }
 640         /*
 641          * Retransmission timer went off.  Message has not
 642          * been acked within retransmit interval.  Back off
 643          * to a longer retransmit interval and retransmit one segment.
 644          */
 645         if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
 646                 tp->t_rxtshift = TCP_MAXRXTSHIFT;
 647                 TCPSTAT_INC(tcps_timeoutdrop);
 648                 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 649                         tcp_inpinfo_lock_del(inp, tp);
 650                         goto out;
 651                 }
 652                 NET_EPOCH_ENTER(et);
 653                 tp = tcp_drop(tp, ETIMEDOUT);
 654                 NET_EPOCH_EXIT(et);
 655                 tcp_inpinfo_lock_del(inp, tp);
 656                 goto out;
 657         }
 658         if (tp->t_state == TCPS_SYN_SENT) {
 659                 /*
 660                  * If the SYN was retransmitted, indicate CWND to be
 661                  * limited to 1 segment in cc_conn_init().
 662                  */
 663                 tp->snd_cwnd = 1;
 664         } else if (tp->t_rxtshift == 1) {
 665                 /*
 666                  * first retransmit; record ssthresh and cwnd so they can
 667                  * be recovered if this turns out to be a "bad" retransmit.
 668                  * A retransmit is considered "bad" if an ACK for this
 669                  * segment is received within RTT/2 interval; the assumption
 670                  * here is that the ACK was already in flight.  See
 671                  * "On Estimating End-to-End Network Path Properties" by
 672                  * Allman and Paxson for more details.
 673                  */
 674                 tp->snd_cwnd_prev = tp->snd_cwnd;
 675                 tp->snd_ssthresh_prev = tp->snd_ssthresh;
 676                 tp->snd_recover_prev = tp->snd_recover;
 677                 if (IN_FASTRECOVERY(tp->t_flags))
 678                         tp->t_flags |= TF_WASFRECOVERY;
 679                 else
 680                         tp->t_flags &= ~TF_WASFRECOVERY;
 681                 if (IN_CONGRECOVERY(tp->t_flags))
 682                         tp->t_flags |= TF_WASCRECOVERY;
 683                 else
 684                         tp->t_flags &= ~TF_WASCRECOVERY;
 685                 if ((tp->t_flags & TF_RCVD_TSTMP) == 0)
 686                         tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
 687                 /* In the event that we've negotiated timestamps
 688                  * badrxtwin will be set to the value that we set
 689                  * the retransmitted packet's to_tsval to by tcp_output
 690                  */
 691                 tp->t_flags |= TF_PREVVALID;
 692         } else
 693                 tp->t_flags &= ~TF_PREVVALID;
 694         TCPSTAT_INC(tcps_rexmttimeo);
 695         if ((tp->t_state == TCPS_SYN_SENT) ||
 696             (tp->t_state == TCPS_SYN_RECEIVED))
 697                 rexmt = tcp_rexmit_initial * tcp_backoff[tp->t_rxtshift];
 698         else
 699                 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
 700         TCPT_RANGESET(tp->t_rxtcur, rexmt,
 701                       tp->t_rttmin, TCPTV_REXMTMAX);
 702
 703         /*
 704          * We enter the path for PLMTUD if connection is established or, if
 705          * connection is FIN_WAIT_1 status, reason for the last is that if
 706          * amount of data we send is very small, we could send it in couple of
 707          * packets and process straight to FIN. In that case we won't catch
 708          * ESTABLISHED state.
 709          */
 710 #ifdef INET6
 711         isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? true : false;
 712 #else
 713         isipv6 = false;
 714 #endif
 715         if (((V_tcp_pmtud_blackhole_detect == 1) ||
 716             (V_tcp_pmtud_blackhole_detect == 2 && !isipv6) ||
 717             (V_tcp_pmtud_blackhole_detect == 3 && isipv6)) &&
 718             ((tp->t_state == TCPS_ESTABLISHED) ||
 719             (tp->t_state == TCPS_FIN_WAIT_1))) {
 720                 if (tp->t_rxtshift == 1) {
 721                         /*
 722                          * We enter blackhole detection after the first
 723                          * unsuccessful timer based retransmission.
 724                          * Then we reduce up to two times the MSS, each
 725                          * candidate giving two tries of retransmissions.
 726                          * But we give a candidate only two tries, if it
 727                          * actually reduces the MSS.
 728                          */
 729                         tp->t_blackhole_enter = 2;
 730                         tp->t_blackhole_exit = tp->t_blackhole_enter;
 731                         if (isipv6) {
 732 #ifdef INET6
 733                                 if (tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss)
 734                                         tp->t_blackhole_exit += 2;
 735                                 if (tp->t_maxseg > V_tcp_v6mssdflt &&
 736                                     V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt)
 737                                         tp->t_blackhole_exit += 2;
 738 #endif
 739                         } else {
 740 #ifdef INET
 741                                 if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss)
 742                                         tp->t_blackhole_exit += 2;
 743                                 if (tp->t_maxseg > V_tcp_mssdflt &&
 744                                     V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt)
 745                                         tp->t_blackhole_exit += 2;
 746 #endif
 747                         }
 748                 }
 749                 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
 750                     (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
 751                     (tp->t_rxtshift >= tp->t_blackhole_enter &&
 752                     tp->t_rxtshift < tp->t_blackhole_exit &&
 753                     (tp->t_rxtshift - tp->t_blackhole_enter) % 2 == 0)) {
 754                         /*
 755                          * Enter Path MTU Black-hole Detection mechanism:
 756                          * - Disable Path MTU Discovery (IP "DF" bit).
 757                          * - Reduce MTU to lower value than what we
 758                          *   negotiated with peer.
 759                          */
 760                         if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) == 0) {
 761                                 /* Record that we may have found a black hole. */
 762                                 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
 763                                 /* Keep track of previous MSS. */
 764                                 tp->t_pmtud_saved_maxseg = tp->t_maxseg;
 765                         }
 766
 767                         /*
 768                          * Reduce the MSS to blackhole value or to the default
 769                          * in an attempt to retransmit.
 770                          */
 771 #ifdef INET6
 772                         if (isipv6 &&
 773                             tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss &&
 774                             V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt) {
 775                                 /* Use the sysctl tuneable blackhole MSS. */
 776                                 tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss;
 777                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
 778                         } else if (isipv6) {
 779                                 /* Use the default MSS. */
 780                                 tp->t_maxseg = V_tcp_v6mssdflt;
 781                                 /*
 782                                  * Disable Path MTU Discovery when we switch to
 783                                  * minmss.
 784                                  */
 785                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 786                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
 787                         }
 788 #endif
 789 #if defined(INET6) && defined(INET)
 790                         else
 791 #endif
 792 #ifdef INET
 793                         if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss &&
 794                             V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt) {
 795                                 /* Use the sysctl tuneable blackhole MSS. */
 796                                 tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
 797                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
 798                         } else {
 799                                 /* Use the default MSS. */
 800                                 tp->t_maxseg = V_tcp_mssdflt;
 801                                 /*
 802                                  * Disable Path MTU Discovery when we switch to
 803                                  * minmss.
 804                                  */
 805                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 806                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
 807                         }
 808 #endif
 809                         /*
 810                          * Reset the slow-start flight size
 811                          * as it may depend on the new MSS.
 812                          */
 813                         if (CC_ALGO(tp)->conn_init != NULL)
 814                                 CC_ALGO(tp)->conn_init(tp->ccv);
 815                 } else {
 816                         /*
 817                          * If further retransmissions are still unsuccessful
 818                          * with a lowered MTU, maybe this isn't a blackhole and
 819                          * we restore the previous MSS and blackhole detection
 820                          * flags.
 821                          */
 822                         if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
 823                             (tp->t_rxtshift >= tp->t_blackhole_exit)) {
 824                                 tp->t_flags2 |= TF2_PLPMTU_PMTUD;
 825                                 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
 826                                 tp->t_maxseg = tp->t_pmtud_saved_maxseg;
 827                                 TCPSTAT_INC(tcps_pmtud_blackhole_failed);
 828                                 /*
 829                                  * Reset the slow-start flight size as it
 830                                  * may depend on the new MSS.
 831                                  */
 832                                 if (CC_ALGO(tp)->conn_init != NULL)
 833                                         CC_ALGO(tp)->conn_init(tp->ccv);
 834                         }
 835                 }
 836         }
 837
 838         /*
 839          * Disable RFC1323 and SACK if we haven't got any response to
 840          * our third SYN to work-around some broken terminal servers
 841          * (most of which have hopefully been retired) that have bad VJ
 842          * header compression code which trashes TCP segments containing
 843          * unknown-to-them TCP options.
 844          */
 845         if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
 846             (tp->t_rxtshift == 3))
 847                 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
 848         /*
 849          * If we backed off this far, notify the L3 protocol that we're having
 850          * connection problems.
 851          */
 852         if (tp->t_rxtshift > TCP_RTT_INVALIDATE) {
 853 #ifdef INET6
 854                 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
 855                         in6_losing(tp->t_inpcb);
 856                 else
 857 #endif
 858                         in_losing(tp->t_inpcb);
 859         }
 860         tp->snd_nxt = tp->snd_una;
 861         tp->snd_recover = tp->snd_max;
 862         /*
 863          * Force a segment to be sent.
 864          */
 865         tp->t_flags |= TF_ACKNOW;
 866         /*
 867          * If timing a segment in this window, stop the timer.
 868          */
 869         tp->t_rtttime = 0;
 870
 871         cc_cong_signal(tp, NULL, CC_RTO);
 872         NET_EPOCH_ENTER(et);
 873         (void) tp->t_fb->tfb_tcp_output(tp);
 874         NET_EPOCH_EXIT(et);
 875 #ifdef TCPDEBUG
 876         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 877                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 878                           PRU_SLOWTIMO);
 879 #endif
 880         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 881         INP_WUNLOCK(inp);
 882 out:
 883         CURVNET_RESTORE();
 884 }
 885
 886 void
 887 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
 888 {
 889         struct callout *t_callout;
 890         callout_func_t *f_callout;
 891         struct inpcb *inp = tp->t_inpcb;
 892         int cpu = inp_to_cpuid(inp);
 893
 894 #ifdef TCP_OFFLOAD
 895         if (tp->t_flags & TF_TOE)
 896                 return;
 897 #endif
 898
 899         if (tp->t_timers->tt_flags & TT_STOPPED)
 900                 return;
 901
 902         switch (timer_type) {
 903                 case TT_DELACK:
 904                         t_callout = &tp->t_timers->tt_delack;
 905                         f_callout = tcp_timer_delack;
 906                         break;
 907                 case TT_REXMT:
 908                         t_callout = &tp->t_timers->tt_rexmt;
 909                         f_callout = tcp_timer_rexmt;
 910                         break;
 911                 case TT_PERSIST:
 912                         t_callout = &tp->t_timers->tt_persist;
 913                         f_callout = tcp_timer_persist;
 914                         break;
 915                 case TT_KEEP:
 916                         t_callout = &tp->t_timers->tt_keep;
 917                         f_callout = tcp_timer_keep;
 918                         break;
 919                 case TT_2MSL:
 920                         t_callout = &tp->t_timers->tt_2msl;
 921                         f_callout = tcp_timer_2msl;
 922                         break;
 923                 default:
 924                         if (tp->t_fb->tfb_tcp_timer_activate) {
 925                                 tp->t_fb->tfb_tcp_timer_activate(tp, timer_type, delta);
 926                                 return;
 927                         }
 928                         panic("tp %p bad timer_type %#x", tp, timer_type);
 929                 }
 930         if (delta == 0) {
 931                 callout_stop(t_callout);
 932         } else {
 933                 callout_reset_on(t_callout, delta, f_callout, tp, cpu);
 934         }
 935 }
 936
 937 int
 938 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type)
 939 {
 940         struct callout *t_callout;
 941
 942         switch (timer_type) {
 943                 case TT_DELACK:
 944                         t_callout = &tp->t_timers->tt_delack;
 945                         break;
 946                 case TT_REXMT:
 947                         t_callout = &tp->t_timers->tt_rexmt;
 948                         break;
 949                 case TT_PERSIST:
 950                         t_callout = &tp->t_timers->tt_persist;
 951                         break;
 952                 case TT_KEEP:
 953                         t_callout = &tp->t_timers->tt_keep;
 954                         break;
 955                 case TT_2MSL:
 956                         t_callout = &tp->t_timers->tt_2msl;
 957                         break;
 958                 default:
 959                         if (tp->t_fb->tfb_tcp_timer_active) {
 960                                 return(tp->t_fb->tfb_tcp_timer_active(tp, timer_type));
 961                         }
 962                         panic("tp %p bad timer_type %#x", tp, timer_type);
 963                 }
 964         return callout_active(t_callout);
 965 }
 966
 967 /*
 968  * Stop the timer from running, and apply a flag
 969  * against the timer_flags that will force the
 970  * timer never to run. The flag is needed to assure
 971  * a race does not leave it running and cause
 972  * the timer to possibly restart itself (keep and persist
 973  * especially do this).
 974  */
 975 int
 976 tcp_timer_suspend(struct tcpcb *tp, uint32_t timer_type)
 977 {
 978         struct callout *t_callout;
 979         uint32_t t_flags;
 980
 981         switch (timer_type) {
 982                 case TT_DELACK:
 983                         t_flags = TT_DELACK_SUS;
 984                         t_callout = &tp->t_timers->tt_delack;
 985                         break;
 986                 case TT_REXMT:
 987                         t_flags = TT_REXMT_SUS;
 988                         t_callout = &tp->t_timers->tt_rexmt;
 989                         break;
 990                 case TT_PERSIST:
 991                         t_flags = TT_PERSIST_SUS;
 992                         t_callout = &tp->t_timers->tt_persist;
 993                         break;
 994                 case TT_KEEP:
 995                         t_flags = TT_KEEP_SUS;
 996                         t_callout = &tp->t_timers->tt_keep;
 997                         break;
 998                 case TT_2MSL:
 999                         t_flags = TT_2MSL_SUS;
1000                         t_callout = &tp->t_timers->tt_2msl;
1001                         break;
1002                 default:
1003                         panic("tp:%p bad timer_type 0x%x", tp, timer_type);
1004         }
1005         tp->t_timers->tt_flags |= t_flags;
1006         return (callout_stop(t_callout));
1007 }
1008
1009 void
1010 tcp_timers_unsuspend(struct tcpcb *tp, uint32_t timer_type)
1011 {
1012         switch (timer_type) {
1013                 case TT_DELACK:
1014                         if (tp->t_timers->tt_flags & TT_DELACK_SUS) {
1015                                 tp->t_timers->tt_flags &= ~TT_DELACK_SUS;
1016                                 if (tp->t_flags & TF_DELACK) {
1017                                         /* Delayed ack timer should be up activate a timer */
1018                                         tp->t_flags &= ~TF_DELACK;
1019                                         tcp_timer_activate(tp, TT_DELACK,
1020                                             tcp_delacktime);
1021                                 }
1022                         }
1023                         break;
1024                 case TT_REXMT:
1025                         if (tp->t_timers->tt_flags & TT_REXMT_SUS) {
1026                                 tp->t_timers->tt_flags &= ~TT_REXMT_SUS;
1027                                 if (SEQ_GT(tp->snd_max, tp->snd_una) &&
1028                                     (tcp_timer_active((tp), TT_PERSIST) == 0) &&
1029                                     tp->snd_wnd) {
1030                                         /* We have outstanding data activate a timer */
1031                                         tcp_timer_activate(tp, TT_REXMT,
1032                                             tp->t_rxtcur);
1033                                 }
1034                         }
1035                         break;
1036                 case TT_PERSIST:
1037                         if (tp->t_timers->tt_flags & TT_PERSIST_SUS) {
1038                                 tp->t_timers->tt_flags &= ~TT_PERSIST_SUS;
1039                                 if (tp->snd_wnd == 0) {
1040                                         /* Activate the persists timer */
1041                                         tp->t_rxtshift = 0;
1042                                         tcp_setpersist(tp);
1043                                 }
1044                         }
1045                         break;
1046                 case TT_KEEP:
1047                         if (tp->t_timers->tt_flags & TT_KEEP_SUS) {
1048                                 tp->t_timers->tt_flags &= ~TT_KEEP_SUS;
1049                                 tcp_timer_activate(tp, TT_KEEP,
1050                                             TCPS_HAVEESTABLISHED(tp->t_state) ?
1051                                             TP_KEEPIDLE(tp) : TP_KEEPINIT(tp));
1052                         }
1053                         break;
1054                 case TT_2MSL:
1055                         if (tp->t_timers->tt_flags &= TT_2MSL_SUS) {
1056                                 tp->t_timers->tt_flags &= ~TT_2MSL_SUS;
1057                                 if ((tp->t_state == TCPS_FIN_WAIT_2) &&
1058                                     ((tp->t_inpcb->inp_socket == NULL) ||
1059                                      (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE))) {
1060                                         /* Star the 2MSL timer */
1061                                         tcp_timer_activate(tp, TT_2MSL,
1062                                             (tcp_fast_finwait2_recycle) ?
1063                                             tcp_finwait2_timeout : TP_MAXIDLE(tp));
1064                                 }
1065                         }
1066                         break;
1067                 default:
1068                         panic("tp:%p bad timer_type 0x%x", tp, timer_type);
1069         }
1070 }
1071
1072 void
1073 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
1074 {
1075         struct callout *t_callout;
1076
1077         tp->t_timers->tt_flags |= TT_STOPPED;
1078         switch (timer_type) {
1079                 case TT_DELACK:
1080                         t_callout = &tp->t_timers->tt_delack;
1081                         break;
1082                 case TT_REXMT:
1083                         t_callout = &tp->t_timers->tt_rexmt;
1084                         break;
1085                 case TT_PERSIST:
1086                         t_callout = &tp->t_timers->tt_persist;
1087                         break;
1088                 case TT_KEEP:
1089                         t_callout = &tp->t_timers->tt_keep;
1090                         break;
1091                 case TT_2MSL:
1092                         t_callout = &tp->t_timers->tt_2msl;
1093                         break;
1094                 default:
1095                         if (tp->t_fb->tfb_tcp_timer_stop) {
1096                                 /*
1097                                  * XXXrrs we need to look at this with the
1098                                  * stop case below (flags).
1099                                  */
1100                                 tp->t_fb->tfb_tcp_timer_stop(tp, timer_type);
1101                                 return;
1102                         }
1103                         panic("tp %p bad timer_type %#x", tp, timer_type);
1104                 }
1105
1106         if (callout_async_drain(t_callout, tcp_timer_discard) == 0) {
1107                 /*
1108                  * Can't stop the callout, defer tcpcb actual deletion
1109                  * to the last one. We do this using the async drain
1110                  * function and incrementing the count in
1111                  */
1112                 tp->t_timers->tt_draincnt++;
1113         }
1114 }