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 #ifdef  RSS
 214         if (per_cpu_timers) {
 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         }
 221 #else
 222         /* Legacy, pre-RSS behaviour */
 223         if (per_cpu_timers) {
 224                 /*
 225                  * We don't have a flowid -> cpuid mapping, so cheat and
 226                  * just map unknown cpuids to curcpu.  Not the best, but
 227                  * apparently better than defaulting to swi 0.
 228                  */
 229                 cpuid = inp->inp_flowid % (mp_maxid + 1);
 230                 if (! CPU_ABSENT(cpuid))
 231                         return (cpuid);
 232                 return (curcpu);
 233         }
 234 #endif
 235         /* Default for RSS and non-RSS - cpuid 0 */
 236         else {
 237                 return (0);
 238         }
 239 }
 240
 241 /*
 242  * Tcp protocol timeout routine called every 500 ms.
 243  * Updates timestamps used for TCP
 244  * causes finite state machine actions if timers expire.
 245  */
 246 void
 247 tcp_slowtimo(void)
 248 {
 249         VNET_ITERATOR_DECL(vnet_iter);
 250
 251         VNET_LIST_RLOCK_NOSLEEP();
 252         VNET_FOREACH(vnet_iter) {
 253                 CURVNET_SET(vnet_iter);
 254                 (void) tcp_tw_2msl_scan(0);
 255                 CURVNET_RESTORE();
 256         }
 257         VNET_LIST_RUNLOCK_NOSLEEP();
 258 }
 259
 260 int     tcp_backoff[TCP_MAXRXTSHIFT + 1] =
 261     { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
 262
 263 int tcp_totbackoff = 2559;      /* sum of tcp_backoff[] */
 264
 265 /*
 266  * TCP timer processing.
 267  */
 268
 269 void
 270 tcp_timer_delack(void *xtp)
 271 {
 272         struct epoch_tracker et;
 273         struct tcpcb *tp = xtp;
 274         struct inpcb *inp;
 275         CURVNET_SET(tp->t_vnet);
 276
 277         inp = tp->t_inpcb;
 278         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 279         INP_WLOCK(inp);
 280         if (callout_pending(&tp->t_timers->tt_delack) ||
 281             !callout_active(&tp->t_timers->tt_delack)) {
 282                 INP_WUNLOCK(inp);
 283                 CURVNET_RESTORE();
 284                 return;
 285         }
 286         callout_deactivate(&tp->t_timers->tt_delack);
 287         if ((inp->inp_flags & INP_DROPPED) != 0) {
 288                 INP_WUNLOCK(inp);
 289                 CURVNET_RESTORE();
 290                 return;
 291         }
 292         tp->t_flags |= TF_ACKNOW;
 293         TCPSTAT_INC(tcps_delack);
 294         NET_EPOCH_ENTER(et);
 295         (void) tcp_output_unlock(tp);
 296         NET_EPOCH_EXIT(et);
 297         CURVNET_RESTORE();
 298 }
 299
 300 void
 301 tcp_inpinfo_lock_del(struct inpcb *inp, struct tcpcb *tp)
 302 {
 303         if (inp && tp != NULL)
 304                 INP_WUNLOCK(inp);
 305 }
 306
 307 void
 308 tcp_timer_2msl(void *xtp)
 309 {
 310         struct tcpcb *tp = xtp;
 311         struct inpcb *inp;
 312         struct epoch_tracker et;
 313         CURVNET_SET(tp->t_vnet);
 314 #ifdef TCPDEBUG
 315         int ostate;
 316
 317         ostate = tp->t_state;
 318 #endif
 319         inp = tp->t_inpcb;
 320         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 321         INP_WLOCK(inp);
 322         tcp_free_sackholes(tp);
 323         if (callout_pending(&tp->t_timers->tt_2msl) ||
 324             !callout_active(&tp->t_timers->tt_2msl)) {
 325                 INP_WUNLOCK(tp->t_inpcb);
 326                 CURVNET_RESTORE();
 327                 return;
 328         }
 329         callout_deactivate(&tp->t_timers->tt_2msl);
 330         if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 331                 INP_WUNLOCK(inp);
 332                 CURVNET_RESTORE();
 333                 return;
 334         }
 335         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 336                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 337         /*
 338          * 2 MSL timeout in shutdown went off.  If we're closed but
 339          * still waiting for peer to close and connection has been idle
 340          * too long delete connection control block.  Otherwise, check
 341          * again in a bit.
 342          *
 343          * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
 344          * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
 345          * Ignore fact that there were recent incoming segments.
 346          */
 347         if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
 348             tp->t_inpcb && tp->t_inpcb->inp_socket &&
 349             (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
 350                 TCPSTAT_INC(tcps_finwait2_drops);
 351                 NET_EPOCH_ENTER(et);
 352                 tp = tcp_close(tp);
 353                 NET_EPOCH_EXIT(et);
 354                 tcp_inpinfo_lock_del(inp, tp);
 355                 goto out;
 356         } else {
 357                 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) {
 358                         callout_reset(&tp->t_timers->tt_2msl,
 359                                       TP_KEEPINTVL(tp), tcp_timer_2msl, tp);
 360                 } else {
 361                         NET_EPOCH_ENTER(et);
 362                         tp = tcp_close(tp);
 363                         NET_EPOCH_EXIT(et);
 364                         tcp_inpinfo_lock_del(inp, tp);
 365                         goto out;
 366                 }
 367         }
 368
 369 #ifdef TCPDEBUG
 370         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 371                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 372                           PRU_SLOWTIMO);
 373 #endif
 374         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 375
 376         if (tp != NULL)
 377                 INP_WUNLOCK(inp);
 378 out:
 379         CURVNET_RESTORE();
 380 }
 381
 382 void
 383 tcp_timer_keep(void *xtp)
 384 {
 385         struct tcpcb *tp = xtp;
 386         struct tcptemp *t_template;
 387         struct inpcb *inp;
 388         struct epoch_tracker et;
 389         CURVNET_SET(tp->t_vnet);
 390 #ifdef TCPDEBUG
 391         int ostate;
 392
 393         ostate = tp->t_state;
 394 #endif
 395         inp = tp->t_inpcb;
 396         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 397         INP_WLOCK(inp);
 398         if (callout_pending(&tp->t_timers->tt_keep) ||
 399             !callout_active(&tp->t_timers->tt_keep)) {
 400                 INP_WUNLOCK(inp);
 401                 CURVNET_RESTORE();
 402                 return;
 403         }
 404         callout_deactivate(&tp->t_timers->tt_keep);
 405         if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 406                 INP_WUNLOCK(inp);
 407                 CURVNET_RESTORE();
 408                 return;
 409         }
 410         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 411                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 412
 413         /*
 414          * Because we don't regularly reset the keepalive callout in
 415          * the ESTABLISHED state, it may be that we don't actually need
 416          * to send a keepalive yet. If that occurs, schedule another
 417          * call for the next time the keepalive timer might expire.
 418          */
 419         if (TCPS_HAVEESTABLISHED(tp->t_state)) {
 420                 u_int idletime;
 421
 422                 idletime = ticks - tp->t_rcvtime;
 423                 if (idletime < TP_KEEPIDLE(tp)) {
 424                         callout_reset(&tp->t_timers->tt_keep,
 425                             TP_KEEPIDLE(tp) - idletime, tcp_timer_keep, tp);
 426                         INP_WUNLOCK(inp);
 427                         CURVNET_RESTORE();
 428                         return;
 429                 }
 430         }
 431
 432         /*
 433          * Keep-alive timer went off; send something
 434          * or drop connection if idle for too long.
 435          */
 436         TCPSTAT_INC(tcps_keeptimeo);
 437         if (tp->t_state < TCPS_ESTABLISHED)
 438                 goto dropit;
 439         if ((V_tcp_always_keepalive ||
 440             inp->inp_socket->so_options & SO_KEEPALIVE) &&
 441             tp->t_state <= TCPS_CLOSING) {
 442                 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
 443                         goto dropit;
 444                 /*
 445                  * Send a packet designed to force a response
 446                  * if the peer is up and reachable:
 447                  * either an ACK if the connection is still alive,
 448                  * or an RST if the peer has closed the connection
 449                  * due to timeout or reboot.
 450                  * Using sequence number tp->snd_una-1
 451                  * causes the transmitted zero-length segment
 452                  * to lie outside the receive window;
 453                  * by the protocol spec, this requires the
 454                  * correspondent TCP to respond.
 455                  */
 456                 TCPSTAT_INC(tcps_keepprobe);
 457                 t_template = tcpip_maketemplate(inp);
 458                 if (t_template) {
 459                         NET_EPOCH_ENTER(et);
 460                         tcp_respond(tp, t_template->tt_ipgen,
 461                                     &t_template->tt_t, (struct mbuf *)NULL,
 462                                     tp->rcv_nxt, tp->snd_una - 1, 0);
 463                         NET_EPOCH_EXIT(et);
 464                         free(t_template, M_TEMP);
 465                 }
 466                 callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
 467                               tcp_timer_keep, tp);
 468         } else
 469                 callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
 470                               tcp_timer_keep, tp);
 471
 472 #ifdef TCPDEBUG
 473         if (inp->inp_socket->so_options & SO_DEBUG)
 474                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 475                           PRU_SLOWTIMO);
 476 #endif
 477         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 478         INP_WUNLOCK(inp);
 479         CURVNET_RESTORE();
 480         return;
 481
 482 dropit:
 483         TCPSTAT_INC(tcps_keepdrops);
 484         NET_EPOCH_ENTER(et);
 485         tp = tcp_drop(tp, ETIMEDOUT);
 486
 487 #ifdef TCPDEBUG
 488         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 489                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 490                           PRU_SLOWTIMO);
 491 #endif
 492         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 493         NET_EPOCH_EXIT(et);
 494         tcp_inpinfo_lock_del(inp, tp);
 495         CURVNET_RESTORE();
 496 }
 497
 498 void
 499 tcp_timer_persist(void *xtp)
 500 {
 501         struct tcpcb *tp = xtp;
 502         struct inpcb *inp;
 503         struct epoch_tracker et;
 504         int outrv;
 505         CURVNET_SET(tp->t_vnet);
 506 #ifdef TCPDEBUG
 507         int ostate;
 508
 509         ostate = tp->t_state;
 510 #endif
 511         inp = tp->t_inpcb;
 512         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 513         INP_WLOCK(inp);
 514         if (callout_pending(&tp->t_timers->tt_persist) ||
 515             !callout_active(&tp->t_timers->tt_persist)) {
 516                 INP_WUNLOCK(inp);
 517                 CURVNET_RESTORE();
 518                 return;
 519         }
 520         callout_deactivate(&tp->t_timers->tt_persist);
 521         if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 522                 INP_WUNLOCK(inp);
 523                 CURVNET_RESTORE();
 524                 return;
 525         }
 526         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 527                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 528         /*
 529          * Persistence timer into zero window.
 530          * Force a byte to be output, if possible.
 531          */
 532         TCPSTAT_INC(tcps_persisttimeo);
 533         /*
 534          * Hack: if the peer is dead/unreachable, we do not
 535          * time out if the window is closed.  After a full
 536          * backoff, drop the connection if the idle time
 537          * (no responses to probes) reaches the maximum
 538          * backoff that we would use if retransmitting.
 539          */
 540         if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
 541             (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
 542              ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
 543                 TCPSTAT_INC(tcps_persistdrop);
 544                 NET_EPOCH_ENTER(et);
 545                 tp = tcp_drop(tp, ETIMEDOUT);
 546                 NET_EPOCH_EXIT(et);
 547                 tcp_inpinfo_lock_del(inp, tp);
 548                 goto out;
 549         }
 550         /*
 551          * If the user has closed the socket then drop a persisting
 552          * connection after a much reduced timeout.
 553          */
 554         if (tp->t_state > TCPS_CLOSE_WAIT &&
 555             (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
 556                 TCPSTAT_INC(tcps_persistdrop);
 557                 NET_EPOCH_ENTER(et);
 558                 tp = tcp_drop(tp, ETIMEDOUT);
 559                 NET_EPOCH_EXIT(et);
 560                 tcp_inpinfo_lock_del(inp, tp);
 561                 goto out;
 562         }
 563         tcp_setpersist(tp);
 564         tp->t_flags |= TF_FORCEDATA;
 565         NET_EPOCH_ENTER(et);
 566         outrv = tcp_output_nodrop(tp);
 567         tp->t_flags &= ~TF_FORCEDATA;
 568
 569 #ifdef TCPDEBUG
 570         if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
 571                 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
 572 #endif
 573         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 574         (void) tcp_unlock_or_drop(tp, outrv);
 575         NET_EPOCH_EXIT(et);
 576 out:
 577         CURVNET_RESTORE();
 578 }
 579
 580 void
 581 tcp_timer_rexmt(void * xtp)
 582 {
 583         struct tcpcb *tp = xtp;
 584         CURVNET_SET(tp->t_vnet);
 585         int rexmt, outrv;
 586         struct inpcb *inp;
 587         struct epoch_tracker et;
 588         bool isipv6;
 589 #ifdef TCPDEBUG
 590         int ostate;
 591
 592         ostate = tp->t_state;
 593 #endif
 594         inp = tp->t_inpcb;
 595         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 596         INP_WLOCK(inp);
 597         if (callout_pending(&tp->t_timers->tt_rexmt) ||
 598             !callout_active(&tp->t_timers->tt_rexmt)) {
 599                 INP_WUNLOCK(inp);
 600                 CURVNET_RESTORE();
 601                 return;
 602         }
 603         callout_deactivate(&tp->t_timers->tt_rexmt);
 604         if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 605                 INP_WUNLOCK(inp);
 606                 CURVNET_RESTORE();
 607                 return;
 608         }
 609         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 610                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 611         tcp_free_sackholes(tp);
 612         TCP_LOG_EVENT(tp, NULL, NULL, NULL, TCP_LOG_RTO, 0, 0, NULL, false);
 613         if (tp->t_fb->tfb_tcp_rexmit_tmr) {
 614                 /* The stack has a timer action too. */
 615                 (*tp->t_fb->tfb_tcp_rexmit_tmr)(tp);
 616         }
 617         /*
 618          * Retransmission timer went off.  Message has not
 619          * been acked within retransmit interval.  Back off
 620          * to a longer retransmit interval and retransmit one segment.
 621          */
 622         if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
 623                 tp->t_rxtshift = TCP_MAXRXTSHIFT;
 624                 TCPSTAT_INC(tcps_timeoutdrop);
 625                 NET_EPOCH_ENTER(et);
 626                 tp = tcp_drop(tp, ETIMEDOUT);
 627                 NET_EPOCH_EXIT(et);
 628                 tcp_inpinfo_lock_del(inp, tp);
 629                 goto out;
 630         }
 631         if (tp->t_state == TCPS_SYN_SENT) {
 632                 /*
 633                  * If the SYN was retransmitted, indicate CWND to be
 634                  * limited to 1 segment in cc_conn_init().
 635                  */
 636                 tp->snd_cwnd = 1;
 637         } else if (tp->t_rxtshift == 1) {
 638                 /*
 639                  * first retransmit; record ssthresh and cwnd so they can
 640                  * be recovered if this turns out to be a "bad" retransmit.
 641                  * A retransmit is considered "bad" if an ACK for this
 642                  * segment is received within RTT/2 interval; the assumption
 643                  * here is that the ACK was already in flight.  See
 644                  * "On Estimating End-to-End Network Path Properties" by
 645                  * Allman and Paxson for more details.
 646                  */
 647                 tp->snd_cwnd_prev = tp->snd_cwnd;
 648                 tp->snd_ssthresh_prev = tp->snd_ssthresh;
 649                 tp->snd_recover_prev = tp->snd_recover;
 650                 if (IN_FASTRECOVERY(tp->t_flags))
 651                         tp->t_flags |= TF_WASFRECOVERY;
 652                 else
 653                         tp->t_flags &= ~TF_WASFRECOVERY;
 654                 if (IN_CONGRECOVERY(tp->t_flags))
 655                         tp->t_flags |= TF_WASCRECOVERY;
 656                 else
 657                         tp->t_flags &= ~TF_WASCRECOVERY;
 658                 if ((tp->t_flags & TF_RCVD_TSTMP) == 0)
 659                         tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
 660                 /* In the event that we've negotiated timestamps
 661                  * badrxtwin will be set to the value that we set
 662                  * the retransmitted packet's to_tsval to by tcp_output
 663                  */
 664                 tp->t_flags |= TF_PREVVALID;
 665         } else
 666                 tp->t_flags &= ~TF_PREVVALID;
 667         TCPSTAT_INC(tcps_rexmttimeo);
 668         if ((tp->t_state == TCPS_SYN_SENT) ||
 669             (tp->t_state == TCPS_SYN_RECEIVED))
 670                 rexmt = tcp_rexmit_initial * tcp_backoff[tp->t_rxtshift];
 671         else
 672                 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
 673         TCPT_RANGESET(tp->t_rxtcur, rexmt,
 674                       tp->t_rttmin, TCPTV_REXMTMAX);
 675
 676         /*
 677          * We enter the path for PLMTUD if connection is established or, if
 678          * connection is FIN_WAIT_1 status, reason for the last is that if
 679          * amount of data we send is very small, we could send it in couple of
 680          * packets and process straight to FIN. In that case we won't catch
 681          * ESTABLISHED state.
 682          */
 683 #ifdef INET6
 684         isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? true : false;
 685 #else
 686         isipv6 = false;
 687 #endif
 688         if (((V_tcp_pmtud_blackhole_detect == 1) ||
 689             (V_tcp_pmtud_blackhole_detect == 2 && !isipv6) ||
 690             (V_tcp_pmtud_blackhole_detect == 3 && isipv6)) &&
 691             ((tp->t_state == TCPS_ESTABLISHED) ||
 692             (tp->t_state == TCPS_FIN_WAIT_1))) {
 693                 if (tp->t_rxtshift == 1) {
 694                         /*
 695                          * We enter blackhole detection after the first
 696                          * unsuccessful timer based retransmission.
 697                          * Then we reduce up to two times the MSS, each
 698                          * candidate giving two tries of retransmissions.
 699                          * But we give a candidate only two tries, if it
 700                          * actually reduces the MSS.
 701                          */
 702                         tp->t_blackhole_enter = 2;
 703                         tp->t_blackhole_exit = tp->t_blackhole_enter;
 704                         if (isipv6) {
 705 #ifdef INET6
 706                                 if (tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss)
 707                                         tp->t_blackhole_exit += 2;
 708                                 if (tp->t_maxseg > V_tcp_v6mssdflt &&
 709                                     V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt)
 710                                         tp->t_blackhole_exit += 2;
 711 #endif
 712                         } else {
 713 #ifdef INET
 714                                 if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss)
 715                                         tp->t_blackhole_exit += 2;
 716                                 if (tp->t_maxseg > V_tcp_mssdflt &&
 717                                     V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt)
 718                                         tp->t_blackhole_exit += 2;
 719 #endif
 720                         }
 721                 }
 722                 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
 723                     (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
 724                     (tp->t_rxtshift >= tp->t_blackhole_enter &&
 725                     tp->t_rxtshift < tp->t_blackhole_exit &&
 726                     (tp->t_rxtshift - tp->t_blackhole_enter) % 2 == 0)) {
 727                         /*
 728                          * Enter Path MTU Black-hole Detection mechanism:
 729                          * - Disable Path MTU Discovery (IP "DF" bit).
 730                          * - Reduce MTU to lower value than what we
 731                          *   negotiated with peer.
 732                          */
 733                         if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) == 0) {
 734                                 /* Record that we may have found a black hole. */
 735                                 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
 736                                 /* Keep track of previous MSS. */
 737                                 tp->t_pmtud_saved_maxseg = tp->t_maxseg;
 738                         }
 739
 740                         /*
 741                          * Reduce the MSS to blackhole value or to the default
 742                          * in an attempt to retransmit.
 743                          */
 744 #ifdef INET6
 745                         if (isipv6 &&
 746                             tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss &&
 747                             V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt) {
 748                                 /* Use the sysctl tuneable blackhole MSS. */
 749                                 tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss;
 750                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
 751                         } else if (isipv6) {
 752                                 /* Use the default MSS. */
 753                                 tp->t_maxseg = V_tcp_v6mssdflt;
 754                                 /*
 755                                  * Disable Path MTU Discovery when we switch to
 756                                  * minmss.
 757                                  */
 758                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 759                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
 760                         }
 761 #endif
 762 #if defined(INET6) && defined(INET)
 763                         else
 764 #endif
 765 #ifdef INET
 766                         if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss &&
 767                             V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt) {
 768                                 /* Use the sysctl tuneable blackhole MSS. */
 769                                 tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
 770                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
 771                         } else {
 772                                 /* Use the default MSS. */
 773                                 tp->t_maxseg = V_tcp_mssdflt;
 774                                 /*
 775                                  * Disable Path MTU Discovery when we switch to
 776                                  * minmss.
 777                                  */
 778                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 779                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
 780                         }
 781 #endif
 782                         /*
 783                          * Reset the slow-start flight size
 784                          * as it may depend on the new MSS.
 785                          */
 786                         if (CC_ALGO(tp)->conn_init != NULL)
 787                                 CC_ALGO(tp)->conn_init(tp->ccv);
 788                 } else {
 789                         /*
 790                          * If further retransmissions are still unsuccessful
 791                          * with a lowered MTU, maybe this isn't a blackhole and
 792                          * we restore the previous MSS and blackhole detection
 793                          * flags.
 794                          */
 795                         if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
 796                             (tp->t_rxtshift >= tp->t_blackhole_exit)) {
 797                                 tp->t_flags2 |= TF2_PLPMTU_PMTUD;
 798                                 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
 799                                 tp->t_maxseg = tp->t_pmtud_saved_maxseg;
 800                                 TCPSTAT_INC(tcps_pmtud_blackhole_failed);
 801                                 /*
 802                                  * Reset the slow-start flight size as it
 803                                  * may depend on the new MSS.
 804                                  */
 805                                 if (CC_ALGO(tp)->conn_init != NULL)
 806                                         CC_ALGO(tp)->conn_init(tp->ccv);
 807                         }
 808                 }
 809         }
 810
 811         /*
 812          * Disable RFC1323 and SACK if we haven't got any response to
 813          * our third SYN to work-around some broken terminal servers
 814          * (most of which have hopefully been retired) that have bad VJ
 815          * header compression code which trashes TCP segments containing
 816          * unknown-to-them TCP options.
 817          */
 818         if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
 819             (tp->t_rxtshift == 3))
 820                 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
 821         /*
 822          * If we backed off this far, notify the L3 protocol that we're having
 823          * connection problems.
 824          */
 825         if (tp->t_rxtshift > TCP_RTT_INVALIDATE) {
 826 #ifdef INET6
 827                 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
 828                         in6_losing(tp->t_inpcb);
 829                 else
 830 #endif
 831                         in_losing(tp->t_inpcb);
 832         }
 833         tp->snd_nxt = tp->snd_una;
 834         tp->snd_recover = tp->snd_max;
 835         /*
 836          * Force a segment to be sent.
 837          */
 838         tp->t_flags |= TF_ACKNOW;
 839         /*
 840          * If timing a segment in this window, stop the timer.
 841          */
 842         tp->t_rtttime = 0;
 843
 844         cc_cong_signal(tp, NULL, CC_RTO);
 845         NET_EPOCH_ENTER(et);
 846         outrv = tcp_output_nodrop(tp);
 847 #ifdef TCPDEBUG
 848         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 849                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 850                           PRU_SLOWTIMO);
 851 #endif
 852         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 853         (void) tcp_unlock_or_drop(tp, outrv);
 854         NET_EPOCH_EXIT(et);
 855 out:
 856         CURVNET_RESTORE();
 857 }
 858
 859 void
 860 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
 861 {
 862         struct callout *t_callout;
 863         callout_func_t *f_callout;
 864         struct inpcb *inp = tp->t_inpcb;
 865         int cpu = inp_to_cpuid(inp);
 866
 867 #ifdef TCP_OFFLOAD
 868         if (tp->t_flags & TF_TOE)
 869                 return;
 870 #endif
 871
 872         if (tp->t_timers->tt_flags & TT_STOPPED)
 873                 return;
 874
 875         switch (timer_type) {
 876                 case TT_DELACK:
 877                         t_callout = &tp->t_timers->tt_delack;
 878                         f_callout = tcp_timer_delack;
 879                         break;
 880                 case TT_REXMT:
 881                         t_callout = &tp->t_timers->tt_rexmt;
 882                         f_callout = tcp_timer_rexmt;
 883                         break;
 884                 case TT_PERSIST:
 885                         t_callout = &tp->t_timers->tt_persist;
 886                         f_callout = tcp_timer_persist;
 887                         break;
 888                 case TT_KEEP:
 889                         t_callout = &tp->t_timers->tt_keep;
 890                         f_callout = tcp_timer_keep;
 891                         break;
 892                 case TT_2MSL:
 893                         t_callout = &tp->t_timers->tt_2msl;
 894                         f_callout = tcp_timer_2msl;
 895                         break;
 896                 default:
 897                         if (tp->t_fb->tfb_tcp_timer_activate) {
 898                                 tp->t_fb->tfb_tcp_timer_activate(tp, timer_type, delta);
 899                                 return;
 900                         }
 901                         panic("tp %p bad timer_type %#x", tp, timer_type);
 902                 }
 903         if (delta == 0) {
 904                 callout_stop(t_callout);
 905         } else {
 906                 callout_reset_on(t_callout, delta, f_callout, tp, cpu);
 907         }
 908 }
 909
 910 int
 911 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type)
 912 {
 913         struct callout *t_callout;
 914
 915         switch (timer_type) {
 916                 case TT_DELACK:
 917                         t_callout = &tp->t_timers->tt_delack;
 918                         break;
 919                 case TT_REXMT:
 920                         t_callout = &tp->t_timers->tt_rexmt;
 921                         break;
 922                 case TT_PERSIST:
 923                         t_callout = &tp->t_timers->tt_persist;
 924                         break;
 925                 case TT_KEEP:
 926                         t_callout = &tp->t_timers->tt_keep;
 927                         break;
 928                 case TT_2MSL:
 929                         t_callout = &tp->t_timers->tt_2msl;
 930                         break;
 931                 default:
 932                         if (tp->t_fb->tfb_tcp_timer_active) {
 933                                 return(tp->t_fb->tfb_tcp_timer_active(tp, timer_type));
 934                         }
 935                         panic("tp %p bad timer_type %#x", tp, timer_type);
 936                 }
 937         return callout_active(t_callout);
 938 }
 939
 940 /*
 941  * Stop the timer from running, and apply a flag
 942  * against the timer_flags that will force the
 943  * timer never to run. The flag is needed to assure
 944  * a race does not leave it running and cause
 945  * the timer to possibly restart itself (keep and persist
 946  * especially do this).
 947  */
 948 int
 949 tcp_timer_suspend(struct tcpcb *tp, uint32_t timer_type)
 950 {
 951         struct callout *t_callout;
 952         uint32_t t_flags;
 953
 954         switch (timer_type) {
 955                 case TT_DELACK:
 956                         t_flags = TT_DELACK_SUS;
 957                         t_callout = &tp->t_timers->tt_delack;
 958                         break;
 959                 case TT_REXMT:
 960                         t_flags = TT_REXMT_SUS;
 961                         t_callout = &tp->t_timers->tt_rexmt;
 962                         break;
 963                 case TT_PERSIST:
 964                         t_flags = TT_PERSIST_SUS;
 965                         t_callout = &tp->t_timers->tt_persist;
 966                         break;
 967                 case TT_KEEP:
 968                         t_flags = TT_KEEP_SUS;
 969                         t_callout = &tp->t_timers->tt_keep;
 970                         break;
 971                 case TT_2MSL:
 972                         t_flags = TT_2MSL_SUS;
 973                         t_callout = &tp->t_timers->tt_2msl;
 974                         break;
 975                 default:
 976                         panic("tp:%p bad timer_type 0x%x", tp, timer_type);
 977         }
 978         tp->t_timers->tt_flags |= t_flags;
 979         return (callout_stop(t_callout));
 980 }
 981
 982 void
 983 tcp_timers_unsuspend(struct tcpcb *tp, uint32_t timer_type)
 984 {
 985         switch (timer_type) {
 986                 case TT_DELACK:
 987                         if (tp->t_timers->tt_flags & TT_DELACK_SUS) {
 988                                 tp->t_timers->tt_flags &= ~TT_DELACK_SUS;
 989                                 if (tp->t_flags & TF_DELACK) {
 990                                         /* Delayed ack timer should be up activate a timer */
 991                                         tp->t_flags &= ~TF_DELACK;
 992                                         tcp_timer_activate(tp, TT_DELACK,
 993                                             tcp_delacktime);
 994                                 }
 995                         }
 996                         break;
 997                 case TT_REXMT:
 998                         if (tp->t_timers->tt_flags & TT_REXMT_SUS) {
 999                                 tp->t_timers->tt_flags &= ~TT_REXMT_SUS;
1000                                 if (SEQ_GT(tp->snd_max, tp->snd_una) &&
1001                                     (tcp_timer_active((tp), TT_PERSIST) == 0) &&
1002                                     tp->snd_wnd) {
1003                                         /* We have outstanding data activate a timer */
1004                                         tcp_timer_activate(tp, TT_REXMT,
1005                                             tp->t_rxtcur);
1006                                 }
1007                         }
1008                         break;
1009                 case TT_PERSIST:
1010                         if (tp->t_timers->tt_flags & TT_PERSIST_SUS) {
1011                                 tp->t_timers->tt_flags &= ~TT_PERSIST_SUS;
1012                                 if (tp->snd_wnd == 0) {
1013                                         /* Activate the persists timer */
1014                                         tp->t_rxtshift = 0;
1015                                         tcp_setpersist(tp);
1016                                 }
1017                         }
1018                         break;
1019                 case TT_KEEP:
1020                         if (tp->t_timers->tt_flags & TT_KEEP_SUS) {
1021                                 tp->t_timers->tt_flags &= ~TT_KEEP_SUS;
1022                                 tcp_timer_activate(tp, TT_KEEP,
1023                                             TCPS_HAVEESTABLISHED(tp->t_state) ?
1024                                             TP_KEEPIDLE(tp) : TP_KEEPINIT(tp));
1025                         }
1026                         break;
1027                 case TT_2MSL:
1028                         if (tp->t_timers->tt_flags &= TT_2MSL_SUS) {
1029                                 tp->t_timers->tt_flags &= ~TT_2MSL_SUS;
1030                                 if ((tp->t_state == TCPS_FIN_WAIT_2) &&
1031                                     ((tp->t_inpcb->inp_socket == NULL) ||
1032                                      (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE))) {
1033                                         /* Star the 2MSL timer */
1034                                         tcp_timer_activate(tp, TT_2MSL,
1035                                             (tcp_fast_finwait2_recycle) ?
1036                                             tcp_finwait2_timeout : TP_MAXIDLE(tp));
1037                                 }
1038                         }
1039                         break;
1040                 default:
1041                         panic("tp:%p bad timer_type 0x%x", tp, timer_type);
1042         }
1043 }
1044
1045 static void
1046 tcp_timer_discard(void *ptp)
1047 {
1048         struct inpcb *inp;
1049         struct tcpcb *tp;
1050         struct epoch_tracker et;
1051
1052         tp = (struct tcpcb *)ptp;
1053         CURVNET_SET(tp->t_vnet);
1054         NET_EPOCH_ENTER(et);
1055         inp = tp->t_inpcb;
1056         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL",
1057                 __func__, tp));
1058         INP_WLOCK(inp);
1059         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) != 0,
1060                 ("%s: tcpcb has to be stopped here", __func__));
1061         if (--tp->t_timers->tt_draincnt > 0 ||
1062             tcp_freecb(tp) == false)
1063                 INP_WUNLOCK(inp);
1064         NET_EPOCH_EXIT(et);
1065         CURVNET_RESTORE();
1066 }
1067
1068 void
1069 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
1070 {
1071         struct callout *t_callout;
1072
1073         tp->t_timers->tt_flags |= TT_STOPPED;
1074         switch (timer_type) {
1075                 case TT_DELACK:
1076                         t_callout = &tp->t_timers->tt_delack;
1077                         break;
1078                 case TT_REXMT:
1079                         t_callout = &tp->t_timers->tt_rexmt;
1080                         break;
1081                 case TT_PERSIST:
1082                         t_callout = &tp->t_timers->tt_persist;
1083                         break;
1084                 case TT_KEEP:
1085                         t_callout = &tp->t_timers->tt_keep;
1086                         break;
1087                 case TT_2MSL:
1088                         t_callout = &tp->t_timers->tt_2msl;
1089                         break;
1090                 default:
1091                         if (tp->t_fb->tfb_tcp_timer_stop) {
1092                                 /*
1093                                  * XXXrrs we need to look at this with the
1094                                  * stop case below (flags).
1095                                  */
1096                                 tp->t_fb->tfb_tcp_timer_stop(tp, timer_type);
1097                                 return;
1098                         }
1099                         panic("tp %p bad timer_type %#x", tp, timer_type);
1100                 }
1101
1102         if (callout_async_drain(t_callout, tcp_timer_discard) == 0) {
1103                 /*
1104                  * Can't stop the callout, defer tcpcb actual deletion
1105                  * to the last one. We do this using the async drain
1106                  * function and incrementing the count in
1107                  */
1108                 tp->t_timers->tt_draincnt++;
1109         }
1110 }