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 #include <netinet/tcp_debug.h>
  81
  82 int    tcp_persmin;
  83 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmin,
  84     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
  85     &tcp_persmin, 0, sysctl_msec_to_ticks, "I",
  86     "minimum persistence interval");
  87
  88 int    tcp_persmax;
  89 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmax,
  90     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
  91     &tcp_persmax, 0, sysctl_msec_to_ticks, "I",
  92     "maximum persistence interval");
  93
  94 int     tcp_keepinit;
  95 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit,
  96     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
  97     &tcp_keepinit, 0, sysctl_msec_to_ticks, "I",
  98     "time to establish connection");
  99
 100 int     tcp_keepidle;
 101 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle,
 102     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 103     &tcp_keepidle, 0, sysctl_msec_to_ticks, "I",
 104     "time before keepalive probes begin");
 105
 106 int     tcp_keepintvl;
 107 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl,
 108     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 109     &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I",
 110     "time between keepalive probes");
 111
 112 int     tcp_delacktime;
 113 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime,
 114     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 115     &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
 116     "Time before a delayed ACK is sent");
 117
 118 VNET_DEFINE(int, tcp_msl);
 119 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl,
 120     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_VNET,
 121     &VNET_NAME(tcp_msl), 0, sysctl_msec_to_ticks, "I",
 122     "Maximum segment lifetime");
 123
 124 int     tcp_rexmit_initial;
 125 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_initial,
 126    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 127     &tcp_rexmit_initial, 0, sysctl_msec_to_ticks, "I",
 128     "Initial Retransmission Timeout");
 129
 130 int     tcp_rexmit_min;
 131 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min,
 132     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 133     &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
 134     "Minimum Retransmission Timeout");
 135
 136 int     tcp_rexmit_slop;
 137 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop,
 138     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 139     &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
 140     "Retransmission Timer Slop");
 141
 142 VNET_DEFINE(int, tcp_always_keepalive) = 1;
 143 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_VNET|CTLFLAG_RW,
 144     &VNET_NAME(tcp_always_keepalive) , 0,
 145     "Assume SO_KEEPALIVE on all TCP connections");
 146
 147 int    tcp_fast_finwait2_recycle = 0;
 148 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
 149     &tcp_fast_finwait2_recycle, 0,
 150     "Recycle closed FIN_WAIT_2 connections faster");
 151
 152 int    tcp_finwait2_timeout;
 153 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout,
 154     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 155     &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I",
 156     "FIN-WAIT2 timeout");
 157
 158 int     tcp_keepcnt = TCPTV_KEEPCNT;
 159 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
 160     "Number of keepalive probes to send");
 161
 162         /* max idle probes */
 163 int     tcp_maxpersistidle;
 164
 165 int     tcp_rexmit_drop_options = 0;
 166 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
 167     &tcp_rexmit_drop_options, 0,
 168     "Drop TCP options from 3rd and later retransmitted SYN");
 169
 170 int     tcp_maxunacktime = TCPTV_MAXUNACKTIME;
 171 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxunacktime,
 172     CTLTYPE_INT|CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 173     &tcp_maxunacktime, 0, sysctl_msec_to_ticks, "I",
 174     "Maximum time (in ms) that a session can linger without making progress");
 175
 176 VNET_DEFINE(int, tcp_pmtud_blackhole_detect);
 177 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection,
 178     CTLFLAG_RW|CTLFLAG_VNET,
 179     &VNET_NAME(tcp_pmtud_blackhole_detect), 0,
 180     "Path MTU Discovery Black Hole Detection Enabled");
 181
 182 #ifdef INET
 183 VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200;
 184 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss,
 185     CTLFLAG_RW|CTLFLAG_VNET,
 186     &VNET_NAME(tcp_pmtud_blackhole_mss), 0,
 187     "Path MTU Discovery Black Hole Detection lowered MSS");
 188 #endif
 189
 190 #ifdef INET6
 191 VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220;
 192 SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss,
 193     CTLFLAG_RW|CTLFLAG_VNET,
 194     &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0,
 195     "Path MTU Discovery IPv6 Black Hole Detection lowered MSS");
 196 #endif
 197
 198 #ifdef  RSS
 199 static int      per_cpu_timers = 1;
 200 #else
 201 static int      per_cpu_timers = 0;
 202 #endif
 203 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
 204     &per_cpu_timers , 0, "run tcp timers on all cpus");
 205
 206 /*
 207  * Map the given inp to a CPU id.
 208  *
 209  * This queries RSS if it's compiled in, else it defaults to the current
 210  * CPU ID.
 211  */
 212 inline int
 213 inp_to_cpuid(struct inpcb *inp)
 214 {
 215         u_int cpuid;
 216
 217         if (per_cpu_timers) {
 218 #ifdef  RSS
 219                 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
 220                 if (cpuid == NETISR_CPUID_NONE)
 221                         return (curcpu);        /* XXX */
 222                 else
 223                         return (cpuid);
 224 #endif
 225                 /*
 226                  * We don't have a flowid -> cpuid mapping, so cheat and
 227                  * just map unknown cpuids to curcpu.  Not the best, but
 228                  * apparently better than defaulting to swi 0.
 229                  */
 230                 cpuid = inp->inp_flowid % (mp_maxid + 1);
 231                 if (! CPU_ABSENT(cpuid))
 232                         return (cpuid);
 233                 return (curcpu);
 234         } else {
 235                 return (0);
 236         }
 237 }
 238
 239 int     tcp_backoff[TCP_MAXRXTSHIFT + 1] =
 240     { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
 241
 242 int tcp_totbackoff = 2559;      /* sum of tcp_backoff[] */
 243
 244 /*
 245  * TCP timer processing.
 246  */
 247
 248 void
 249 tcp_timer_delack(void *xtp)
 250 {
 251         struct epoch_tracker et;
 252         struct tcpcb *tp = xtp;
 253         struct inpcb *inp = tptoinpcb(tp);
 254
 255         INP_WLOCK(inp);
 256         CURVNET_SET(inp->inp_vnet);
 257
 258         if (callout_pending(&tp->t_timers->tt_delack) ||
 259             !callout_active(&tp->t_timers->tt_delack)) {
 260                 INP_WUNLOCK(inp);
 261                 CURVNET_RESTORE();
 262                 return;
 263         }
 264         callout_deactivate(&tp->t_timers->tt_delack);
 265         if ((inp->inp_flags & INP_DROPPED) != 0) {
 266                 INP_WUNLOCK(inp);
 267                 CURVNET_RESTORE();
 268                 return;
 269         }
 270         tp->t_flags |= TF_ACKNOW;
 271         TCPSTAT_INC(tcps_delack);
 272         NET_EPOCH_ENTER(et);
 273         (void) tcp_output_unlock(tp);
 274         NET_EPOCH_EXIT(et);
 275         CURVNET_RESTORE();
 276 }
 277
 278 /*
 279  * Call tcp_close() from a callout context.
 280  */
 281 static void
 282 tcp_timer_close(struct tcpcb *tp)
 283 {
 284         struct epoch_tracker et;
 285         struct inpcb *inp = tptoinpcb(tp);
 286
 287         INP_WLOCK_ASSERT(inp);
 288
 289         NET_EPOCH_ENTER(et);
 290         tp = tcp_close(tp);
 291         NET_EPOCH_EXIT(et);
 292         if (tp != NULL)
 293                 INP_WUNLOCK(inp);
 294 }
 295
 296 /*
 297  * Call tcp_drop() from a callout context.
 298  */
 299 static void
 300 tcp_timer_drop(struct tcpcb *tp)
 301 {
 302         struct epoch_tracker et;
 303         struct inpcb *inp = tptoinpcb(tp);
 304
 305         INP_WLOCK_ASSERT(inp);
 306
 307         NET_EPOCH_ENTER(et);
 308         tp = tcp_drop(tp, ETIMEDOUT);
 309         NET_EPOCH_EXIT(et);
 310         if (tp != NULL)
 311                 INP_WUNLOCK(inp);
 312 }
 313
 314 void
 315 tcp_timer_2msl(void *xtp)
 316 {
 317         struct tcpcb *tp = xtp;
 318         struct inpcb *inp = tptoinpcb(tp);
 319 #ifdef TCPDEBUG
 320         int ostate;
 321
 322         ostate = tp->t_state;
 323 #endif
 324
 325         INP_WLOCK(inp);
 326         CURVNET_SET(inp->inp_vnet);
 327
 328         tcp_log_end_status(tp, TCP_EI_STATUS_2MSL);
 329         tcp_free_sackholes(tp);
 330         if (callout_pending(&tp->t_timers->tt_2msl) ||
 331             !callout_active(&tp->t_timers->tt_2msl)) {
 332                 INP_WUNLOCK(inp);
 333                 CURVNET_RESTORE();
 334                 return;
 335         }
 336         callout_deactivate(&tp->t_timers->tt_2msl);
 337         if (inp->inp_flags & INP_DROPPED) {
 338                 INP_WUNLOCK(inp);
 339                 CURVNET_RESTORE();
 340                 return;
 341         }
 342         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 343                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 344         /*
 345          * 2 MSL timeout in shutdown went off.  If we're closed but
 346          * still waiting for peer to close and connection has been idle
 347          * too long delete connection control block.  Otherwise, check
 348          * again in a bit.
 349          *
 350          * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
 351          * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
 352          * Ignore fact that there were recent incoming segments.
 353          *
 354          * XXXGL: check if inp_socket shall always be !NULL here?
 355          */
 356         if (tp->t_state == TCPS_TIME_WAIT) {
 357                 tcp_timer_close(tp);
 358                 CURVNET_RESTORE();
 359                 return;
 360         } else if (tp->t_state == TCPS_FIN_WAIT_2 &&
 361             tcp_fast_finwait2_recycle && inp->inp_socket &&
 362             (inp->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
 363                 TCPSTAT_INC(tcps_finwait2_drops);
 364                 tcp_timer_close(tp);
 365                 CURVNET_RESTORE();
 366                 return;
 367         } else {
 368                 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) {
 369                         callout_reset(&tp->t_timers->tt_2msl,
 370                                       TP_KEEPINTVL(tp), tcp_timer_2msl, tp);
 371                 } else {
 372                         tcp_timer_close(tp);
 373                         CURVNET_RESTORE();
 374                         return;
 375                 }
 376         }
 377
 378 #ifdef TCPDEBUG
 379         if (tptosocket(tp)->so_options & SO_DEBUG)
 380                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 381                           PRU_SLOWTIMO);
 382 #endif
 383         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 384
 385         INP_WUNLOCK(inp);
 386         CURVNET_RESTORE();
 387 }
 388
 389 void
 390 tcp_timer_keep(void *xtp)
 391 {
 392         struct epoch_tracker et;
 393         struct tcpcb *tp = xtp;
 394         struct inpcb *inp = tptoinpcb(tp);
 395         struct tcptemp *t_template;
 396 #ifdef TCPDEBUG
 397         int ostate;
 398
 399         ostate = tp->t_state;
 400 #endif
 401
 402         INP_WLOCK(inp);
 403         CURVNET_SET(inp->inp_vnet);
 404
 405         if (callout_pending(&tp->t_timers->tt_keep) ||
 406             !callout_active(&tp->t_timers->tt_keep)) {
 407                 INP_WUNLOCK(inp);
 408                 CURVNET_RESTORE();
 409                 return;
 410         }
 411         callout_deactivate(&tp->t_timers->tt_keep);
 412         if (inp->inp_flags & INP_DROPPED) {
 413                 INP_WUNLOCK(inp);
 414                 CURVNET_RESTORE();
 415                 return;
 416         }
 417         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 418                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 419
 420         /*
 421          * Because we don't regularly reset the keepalive callout in
 422          * the ESTABLISHED state, it may be that we don't actually need
 423          * to send a keepalive yet. If that occurs, schedule another
 424          * call for the next time the keepalive timer might expire.
 425          */
 426         if (TCPS_HAVEESTABLISHED(tp->t_state)) {
 427                 u_int idletime;
 428
 429                 idletime = ticks - tp->t_rcvtime;
 430                 if (idletime < TP_KEEPIDLE(tp)) {
 431                         callout_reset(&tp->t_timers->tt_keep,
 432                             TP_KEEPIDLE(tp) - idletime, tcp_timer_keep, tp);
 433                         INP_WUNLOCK(inp);
 434                         CURVNET_RESTORE();
 435                         return;
 436                 }
 437         }
 438
 439         /*
 440          * Keep-alive timer went off; send something
 441          * or drop connection if idle for too long.
 442          */
 443         TCPSTAT_INC(tcps_keeptimeo);
 444         if (tp->t_state < TCPS_ESTABLISHED)
 445                 goto dropit;
 446         if ((V_tcp_always_keepalive ||
 447             inp->inp_socket->so_options & SO_KEEPALIVE) &&
 448             tp->t_state <= TCPS_CLOSING) {
 449                 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
 450                         goto dropit;
 451                 /*
 452                  * Send a packet designed to force a response
 453                  * if the peer is up and reachable:
 454                  * either an ACK if the connection is still alive,
 455                  * or an RST if the peer has closed the connection
 456                  * due to timeout or reboot.
 457                  * Using sequence number tp->snd_una-1
 458                  * causes the transmitted zero-length segment
 459                  * to lie outside the receive window;
 460                  * by the protocol spec, this requires the
 461                  * correspondent TCP to respond.
 462                  */
 463                 TCPSTAT_INC(tcps_keepprobe);
 464                 t_template = tcpip_maketemplate(inp);
 465                 if (t_template) {
 466                         NET_EPOCH_ENTER(et);
 467                         tcp_respond(tp, t_template->tt_ipgen,
 468                                     &t_template->tt_t, (struct mbuf *)NULL,
 469                                     tp->rcv_nxt, tp->snd_una - 1, 0);
 470                         NET_EPOCH_EXIT(et);
 471                         free(t_template, M_TEMP);
 472                 }
 473                 callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
 474                               tcp_timer_keep, tp);
 475         } else
 476                 callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
 477                               tcp_timer_keep, tp);
 478
 479 #ifdef TCPDEBUG
 480         if (inp->inp_socket->so_options & SO_DEBUG)
 481                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 482                           PRU_SLOWTIMO);
 483 #endif
 484         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 485         INP_WUNLOCK(inp);
 486         CURVNET_RESTORE();
 487         return;
 488
 489 dropit:
 490         TCPSTAT_INC(tcps_keepdrops);
 491         NET_EPOCH_ENTER(et);
 492         tcp_log_end_status(tp, TCP_EI_STATUS_KEEP_MAX);
 493         tp = tcp_drop(tp, ETIMEDOUT);
 494
 495 #ifdef TCPDEBUG
 496         if (tp != NULL && (tptosocket(tp)->so_options & SO_DEBUG))
 497                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 498                           PRU_SLOWTIMO);
 499 #endif
 500         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 501         NET_EPOCH_EXIT(et);
 502         if (tp != NULL)
 503                 INP_WUNLOCK(inp);
 504         CURVNET_RESTORE();
 505 }
 506
 507 /*
 508  * Has this session exceeded the maximum time without seeing a substantive
 509  * acknowledgement? If so, return true; otherwise false.
 510  */
 511 static bool
 512 tcp_maxunacktime_check(struct tcpcb *tp)
 513 {
 514
 515         /* Are we tracking this timer for this session? */
 516         if (TP_MAXUNACKTIME(tp) == 0)
 517                 return false;
 518
 519         /* Do we have a current measurement. */
 520         if (tp->t_acktime == 0)
 521                 return false;
 522
 523         /* Are we within the acceptable range? */
 524         if (TSTMP_GT(TP_MAXUNACKTIME(tp) + tp->t_acktime, (u_int)ticks))
 525                 return false;
 526
 527         /* We exceeded the timer. */
 528         TCPSTAT_INC(tcps_progdrops);
 529         return true;
 530 }
 531
 532 void
 533 tcp_timer_persist(void *xtp)
 534 {
 535         struct epoch_tracker et;
 536         struct tcpcb *tp = xtp;
 537         struct inpcb *inp = tptoinpcb(tp);
 538         bool progdrop;
 539         int outrv;
 540 #ifdef TCPDEBUG
 541         int ostate;
 542
 543         ostate = tp->t_state;
 544 #endif
 545
 546         INP_WLOCK(inp);
 547         CURVNET_SET(inp->inp_vnet);
 548
 549         if (callout_pending(&tp->t_timers->tt_persist) ||
 550             !callout_active(&tp->t_timers->tt_persist)) {
 551                 INP_WUNLOCK(inp);
 552                 CURVNET_RESTORE();
 553                 return;
 554         }
 555         callout_deactivate(&tp->t_timers->tt_persist);
 556         if (inp->inp_flags & INP_DROPPED) {
 557                 INP_WUNLOCK(inp);
 558                 CURVNET_RESTORE();
 559                 return;
 560         }
 561         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 562                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 563         /*
 564          * Persistence timer into zero window.
 565          * Force a byte to be output, if possible.
 566          */
 567         TCPSTAT_INC(tcps_persisttimeo);
 568         /*
 569          * Hack: if the peer is dead/unreachable, we do not
 570          * time out if the window is closed.  After a full
 571          * backoff, drop the connection if the idle time
 572          * (no responses to probes) reaches the maximum
 573          * backoff that we would use if retransmitting.
 574          * Also, drop the connection if we haven't been making
 575          * progress.
 576          */
 577         progdrop = tcp_maxunacktime_check(tp);
 578         if (progdrop || (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
 579             (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
 580              ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff))) {
 581                 if (!progdrop)
 582                         TCPSTAT_INC(tcps_persistdrop);
 583                 tcp_log_end_status(tp, TCP_EI_STATUS_PERSIST_MAX);
 584                 tcp_timer_drop(tp);
 585                 CURVNET_RESTORE();
 586                 return;
 587         }
 588         /*
 589          * If the user has closed the socket then drop a persisting
 590          * connection after a much reduced timeout.
 591          */
 592         if (tp->t_state > TCPS_CLOSE_WAIT &&
 593             (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
 594                 TCPSTAT_INC(tcps_persistdrop);
 595                 tcp_log_end_status(tp, TCP_EI_STATUS_PERSIST_MAX);
 596                 tcp_timer_drop(tp);
 597                 CURVNET_RESTORE();
 598                 return;
 599         }
 600         tcp_setpersist(tp);
 601         tp->t_flags |= TF_FORCEDATA;
 602         NET_EPOCH_ENTER(et);
 603         outrv = tcp_output_nodrop(tp);
 604         tp->t_flags &= ~TF_FORCEDATA;
 605
 606 #ifdef TCPDEBUG
 607         if (tp != NULL && tptosocket(tp)->so_options & SO_DEBUG)
 608                 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
 609 #endif
 610         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 611         (void) tcp_unlock_or_drop(tp, outrv);
 612         NET_EPOCH_EXIT(et);
 613         CURVNET_RESTORE();
 614 }
 615
 616 void
 617 tcp_timer_rexmt(void * xtp)
 618 {
 619         struct epoch_tracker et;
 620         struct tcpcb *tp = xtp;
 621         struct inpcb *inp = tptoinpcb(tp);
 622         int rexmt, outrv;
 623         bool isipv6;
 624 #ifdef TCPDEBUG
 625         int ostate;
 626
 627         ostate = tp->t_state;
 628 #endif
 629
 630         INP_WLOCK(inp);
 631         CURVNET_SET(inp->inp_vnet);
 632
 633         if (callout_pending(&tp->t_timers->tt_rexmt) ||
 634             !callout_active(&tp->t_timers->tt_rexmt)) {
 635                 INP_WUNLOCK(inp);
 636                 CURVNET_RESTORE();
 637                 return;
 638         }
 639         callout_deactivate(&tp->t_timers->tt_rexmt);
 640         if (inp->inp_flags & INP_DROPPED) {
 641                 INP_WUNLOCK(inp);
 642                 CURVNET_RESTORE();
 643                 return;
 644         }
 645         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 646                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 647         tcp_free_sackholes(tp);
 648         TCP_LOG_EVENT(tp, NULL, NULL, NULL, TCP_LOG_RTO, 0, 0, NULL, false);
 649         if (tp->t_fb->tfb_tcp_rexmit_tmr) {
 650                 /* The stack has a timer action too. */
 651                 (*tp->t_fb->tfb_tcp_rexmit_tmr)(tp);
 652         }
 653         /*
 654          * Retransmission timer went off.  Message has not
 655          * been acked within retransmit interval.  Back off
 656          * to a longer retransmit interval and retransmit one segment.
 657          *
 658          * If we've either exceeded the maximum number of retransmissions,
 659          * or we've gone long enough without making progress, then drop
 660          * the session.
 661          */
 662         if (++tp->t_rxtshift > TCP_MAXRXTSHIFT || tcp_maxunacktime_check(tp)) {
 663                 if (tp->t_rxtshift > TCP_MAXRXTSHIFT)
 664                         TCPSTAT_INC(tcps_timeoutdrop);
 665                 tp->t_rxtshift = TCP_MAXRXTSHIFT;
 666                 tcp_log_end_status(tp, TCP_EI_STATUS_RETRAN);
 667                 tcp_timer_drop(tp);
 668                 CURVNET_RESTORE();
 669                 return;
 670         }
 671         if (tp->t_state == TCPS_SYN_SENT) {
 672                 /*
 673                  * If the SYN was retransmitted, indicate CWND to be
 674                  * limited to 1 segment in cc_conn_init().
 675                  */
 676                 tp->snd_cwnd = 1;
 677         } else if (tp->t_rxtshift == 1) {
 678                 /*
 679                  * first retransmit; record ssthresh and cwnd so they can
 680                  * be recovered if this turns out to be a "bad" retransmit.
 681                  * A retransmit is considered "bad" if an ACK for this
 682                  * segment is received within RTT/2 interval; the assumption
 683                  * here is that the ACK was already in flight.  See
 684                  * "On Estimating End-to-End Network Path Properties" by
 685                  * Allman and Paxson for more details.
 686                  */
 687                 tp->snd_cwnd_prev = tp->snd_cwnd;
 688                 tp->snd_ssthresh_prev = tp->snd_ssthresh;
 689                 tp->snd_recover_prev = tp->snd_recover;
 690                 if (IN_FASTRECOVERY(tp->t_flags))
 691                         tp->t_flags |= TF_WASFRECOVERY;
 692                 else
 693                         tp->t_flags &= ~TF_WASFRECOVERY;
 694                 if (IN_CONGRECOVERY(tp->t_flags))
 695                         tp->t_flags |= TF_WASCRECOVERY;
 696                 else
 697                         tp->t_flags &= ~TF_WASCRECOVERY;
 698                 if ((tp->t_flags & TF_RCVD_TSTMP) == 0)
 699                         tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
 700                 /* In the event that we've negotiated timestamps
 701                  * badrxtwin will be set to the value that we set
 702                  * the retransmitted packet's to_tsval to by tcp_output
 703                  */
 704                 tp->t_flags |= TF_PREVVALID;
 705         } else
 706                 tp->t_flags &= ~TF_PREVVALID;
 707         TCPSTAT_INC(tcps_rexmttimeo);
 708         if ((tp->t_state == TCPS_SYN_SENT) ||
 709             (tp->t_state == TCPS_SYN_RECEIVED))
 710                 rexmt = tcp_rexmit_initial * tcp_backoff[tp->t_rxtshift];
 711         else
 712                 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
 713         TCPT_RANGESET(tp->t_rxtcur, rexmt,
 714                       tp->t_rttmin, TCPTV_REXMTMAX);
 715
 716         /*
 717          * We enter the path for PLMTUD if connection is established or, if
 718          * connection is FIN_WAIT_1 status, reason for the last is that if
 719          * amount of data we send is very small, we could send it in couple of
 720          * packets and process straight to FIN. In that case we won't catch
 721          * ESTABLISHED state.
 722          */
 723 #ifdef INET6
 724         isipv6 = (inp->inp_vflag & INP_IPV6) ? true : false;
 725 #else
 726         isipv6 = false;
 727 #endif
 728         if (((V_tcp_pmtud_blackhole_detect == 1) ||
 729             (V_tcp_pmtud_blackhole_detect == 2 && !isipv6) ||
 730             (V_tcp_pmtud_blackhole_detect == 3 && isipv6)) &&
 731             ((tp->t_state == TCPS_ESTABLISHED) ||
 732             (tp->t_state == TCPS_FIN_WAIT_1))) {
 733                 if (tp->t_rxtshift == 1) {
 734                         /*
 735                          * We enter blackhole detection after the first
 736                          * unsuccessful timer based retransmission.
 737                          * Then we reduce up to two times the MSS, each
 738                          * candidate giving two tries of retransmissions.
 739                          * But we give a candidate only two tries, if it
 740                          * actually reduces the MSS.
 741                          */
 742                         tp->t_blackhole_enter = 2;
 743                         tp->t_blackhole_exit = tp->t_blackhole_enter;
 744                         if (isipv6) {
 745 #ifdef INET6
 746                                 if (tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss)
 747                                         tp->t_blackhole_exit += 2;
 748                                 if (tp->t_maxseg > V_tcp_v6mssdflt &&
 749                                     V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt)
 750                                         tp->t_blackhole_exit += 2;
 751 #endif
 752                         } else {
 753 #ifdef INET
 754                                 if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss)
 755                                         tp->t_blackhole_exit += 2;
 756                                 if (tp->t_maxseg > V_tcp_mssdflt &&
 757                                     V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt)
 758                                         tp->t_blackhole_exit += 2;
 759 #endif
 760                         }
 761                 }
 762                 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
 763                     (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
 764                     (tp->t_rxtshift >= tp->t_blackhole_enter &&
 765                     tp->t_rxtshift < tp->t_blackhole_exit &&
 766                     (tp->t_rxtshift - tp->t_blackhole_enter) % 2 == 0)) {
 767                         /*
 768                          * Enter Path MTU Black-hole Detection mechanism:
 769                          * - Disable Path MTU Discovery (IP "DF" bit).
 770                          * - Reduce MTU to lower value than what we
 771                          *   negotiated with peer.
 772                          */
 773                         if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) == 0) {
 774                                 /* Record that we may have found a black hole. */
 775                                 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
 776                                 /* Keep track of previous MSS. */
 777                                 tp->t_pmtud_saved_maxseg = tp->t_maxseg;
 778                         }
 779
 780                         /*
 781                          * Reduce the MSS to blackhole value or to the default
 782                          * in an attempt to retransmit.
 783                          */
 784 #ifdef INET6
 785                         if (isipv6 &&
 786                             tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss &&
 787                             V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt) {
 788                                 /* Use the sysctl tuneable blackhole MSS. */
 789                                 tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss;
 790                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
 791                         } else if (isipv6) {
 792                                 /* Use the default MSS. */
 793                                 tp->t_maxseg = V_tcp_v6mssdflt;
 794                                 /*
 795                                  * Disable Path MTU Discovery when we switch to
 796                                  * minmss.
 797                                  */
 798                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 799                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
 800                         }
 801 #endif
 802 #if defined(INET6) && defined(INET)
 803                         else
 804 #endif
 805 #ifdef INET
 806                         if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss &&
 807                             V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt) {
 808                                 /* Use the sysctl tuneable blackhole MSS. */
 809                                 tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
 810                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
 811                         } else {
 812                                 /* Use the default MSS. */
 813                                 tp->t_maxseg = V_tcp_mssdflt;
 814                                 /*
 815                                  * Disable Path MTU Discovery when we switch to
 816                                  * minmss.
 817                                  */
 818                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 819                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
 820                         }
 821 #endif
 822                         /*
 823                          * Reset the slow-start flight size
 824                          * as it may depend on the new MSS.
 825                          */
 826                         if (CC_ALGO(tp)->conn_init != NULL)
 827                                 CC_ALGO(tp)->conn_init(tp->ccv);
 828                 } else {
 829                         /*
 830                          * If further retransmissions are still unsuccessful
 831                          * with a lowered MTU, maybe this isn't a blackhole and
 832                          * we restore the previous MSS and blackhole detection
 833                          * flags.
 834                          */
 835                         if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
 836                             (tp->t_rxtshift >= tp->t_blackhole_exit)) {
 837                                 tp->t_flags2 |= TF2_PLPMTU_PMTUD;
 838                                 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
 839                                 tp->t_maxseg = tp->t_pmtud_saved_maxseg;
 840                                 TCPSTAT_INC(tcps_pmtud_blackhole_failed);
 841                                 /*
 842                                  * Reset the slow-start flight size as it
 843                                  * may depend on the new MSS.
 844                                  */
 845                                 if (CC_ALGO(tp)->conn_init != NULL)
 846                                         CC_ALGO(tp)->conn_init(tp->ccv);
 847                         }
 848                 }
 849         }
 850
 851         /*
 852          * Disable RFC1323 and SACK if we haven't got any response to
 853          * our third SYN to work-around some broken terminal servers
 854          * (most of which have hopefully been retired) that have bad VJ
 855          * header compression code which trashes TCP segments containing
 856          * unknown-to-them TCP options.
 857          */
 858         if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
 859             (tp->t_rxtshift == 3))
 860                 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
 861         /*
 862          * If we backed off this far, notify the L3 protocol that we're having
 863          * connection problems.
 864          */
 865         if (tp->t_rxtshift > TCP_RTT_INVALIDATE) {
 866 #ifdef INET6
 867                 if ((inp->inp_vflag & INP_IPV6) != 0)
 868                         in6_losing(inp);
 869                 else
 870 #endif
 871                         in_losing(inp);
 872         }
 873         tp->snd_nxt = tp->snd_una;
 874         tp->snd_recover = tp->snd_max;
 875         /*
 876          * Force a segment to be sent.
 877          */
 878         tp->t_flags |= TF_ACKNOW;
 879         /*
 880          * If timing a segment in this window, stop the timer.
 881          */
 882         tp->t_rtttime = 0;
 883
 884         cc_cong_signal(tp, NULL, CC_RTO);
 885         NET_EPOCH_ENTER(et);
 886         outrv = tcp_output_nodrop(tp);
 887 #ifdef TCPDEBUG
 888         if (tp != NULL && (tptosocket(tp)->so_options & SO_DEBUG))
 889                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 890                           PRU_SLOWTIMO);
 891 #endif
 892         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 893         (void) tcp_unlock_or_drop(tp, outrv);
 894         NET_EPOCH_EXIT(et);
 895         CURVNET_RESTORE();
 896 }
 897
 898 void
 899 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
 900 {
 901         struct callout *t_callout;
 902         callout_func_t *f_callout;
 903         struct inpcb *inp = tptoinpcb(tp);
 904         int cpu = inp_to_cpuid(inp);
 905
 906 #ifdef TCP_OFFLOAD
 907         if (tp->t_flags & TF_TOE)
 908                 return;
 909 #endif
 910
 911         if (tp->t_timers->tt_flags & TT_STOPPED)
 912                 return;
 913
 914         switch (timer_type) {
 915                 case TT_DELACK:
 916                         t_callout = &tp->t_timers->tt_delack;
 917                         f_callout = tcp_timer_delack;
 918                         break;
 919                 case TT_REXMT:
 920                         t_callout = &tp->t_timers->tt_rexmt;
 921                         f_callout = tcp_timer_rexmt;
 922                         break;
 923                 case TT_PERSIST:
 924                         t_callout = &tp->t_timers->tt_persist;
 925                         f_callout = tcp_timer_persist;
 926                         break;
 927                 case TT_KEEP:
 928                         t_callout = &tp->t_timers->tt_keep;
 929                         f_callout = tcp_timer_keep;
 930                         break;
 931                 case TT_2MSL:
 932                         t_callout = &tp->t_timers->tt_2msl;
 933                         f_callout = tcp_timer_2msl;
 934                         break;
 935                 default:
 936                         if (tp->t_fb->tfb_tcp_timer_activate) {
 937                                 tp->t_fb->tfb_tcp_timer_activate(tp, timer_type, delta);
 938                                 return;
 939                         }
 940                         panic("tp %p bad timer_type %#x", tp, timer_type);
 941                 }
 942         if (delta == 0) {
 943                 callout_stop(t_callout);
 944         } else {
 945                 callout_reset_on(t_callout, delta, f_callout, tp, cpu);
 946         }
 947 }
 948
 949 int
 950 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type)
 951 {
 952         struct callout *t_callout;
 953
 954         switch (timer_type) {
 955                 case TT_DELACK:
 956                         t_callout = &tp->t_timers->tt_delack;
 957                         break;
 958                 case TT_REXMT:
 959                         t_callout = &tp->t_timers->tt_rexmt;
 960                         break;
 961                 case TT_PERSIST:
 962                         t_callout = &tp->t_timers->tt_persist;
 963                         break;
 964                 case TT_KEEP:
 965                         t_callout = &tp->t_timers->tt_keep;
 966                         break;
 967                 case TT_2MSL:
 968                         t_callout = &tp->t_timers->tt_2msl;
 969                         break;
 970                 default:
 971                         if (tp->t_fb->tfb_tcp_timer_active) {
 972                                 return(tp->t_fb->tfb_tcp_timer_active(tp, timer_type));
 973                         }
 974                         panic("tp %p bad timer_type %#x", tp, timer_type);
 975                 }
 976         return callout_active(t_callout);
 977 }
 978
 979 /*
 980  * Stop the timer from running, and apply a flag
 981  * against the timer_flags that will force the
 982  * timer never to run. The flag is needed to assure
 983  * a race does not leave it running and cause
 984  * the timer to possibly restart itself (keep and persist
 985  * especially do this).
 986  */
 987 int
 988 tcp_timer_suspend(struct tcpcb *tp, uint32_t timer_type)
 989 {
 990         struct callout *t_callout;
 991         uint32_t t_flags;
 992
 993         switch (timer_type) {
 994                 case TT_DELACK:
 995                         t_flags = TT_DELACK_SUS;
 996                         t_callout = &tp->t_timers->tt_delack;
 997                         break;
 998                 case TT_REXMT:
 999                         t_flags = TT_REXMT_SUS;
1000                         t_callout = &tp->t_timers->tt_rexmt;
1001                         break;
1002                 case TT_PERSIST:
1003                         t_flags = TT_PERSIST_SUS;
1004                         t_callout = &tp->t_timers->tt_persist;
1005                         break;
1006                 case TT_KEEP:
1007                         t_flags = TT_KEEP_SUS;
1008                         t_callout = &tp->t_timers->tt_keep;
1009                         break;
1010                 case TT_2MSL:
1011                         t_flags = TT_2MSL_SUS;
1012                         t_callout = &tp->t_timers->tt_2msl;
1013                         break;
1014                 default:
1015                         panic("tp:%p bad timer_type 0x%x", tp, timer_type);
1016         }
1017         tp->t_timers->tt_flags |= t_flags;
1018         return (callout_stop(t_callout));
1019 }
1020
1021 void
1022 tcp_timers_unsuspend(struct tcpcb *tp, uint32_t timer_type)
1023 {
1024         switch (timer_type) {
1025                 case TT_DELACK:
1026                         if (tp->t_timers->tt_flags & TT_DELACK_SUS) {
1027                                 tp->t_timers->tt_flags &= ~TT_DELACK_SUS;
1028                                 if (tp->t_flags & TF_DELACK) {
1029                                         /* Delayed ack timer should be up activate a timer */
1030                                         tp->t_flags &= ~TF_DELACK;
1031                                         tcp_timer_activate(tp, TT_DELACK,
1032                                             tcp_delacktime);
1033                                 }
1034                         }
1035                         break;
1036                 case TT_REXMT:
1037                         if (tp->t_timers->tt_flags & TT_REXMT_SUS) {
1038                                 tp->t_timers->tt_flags &= ~TT_REXMT_SUS;
1039                                 if (SEQ_GT(tp->snd_max, tp->snd_una) &&
1040                                     (tcp_timer_active((tp), TT_PERSIST) == 0) &&
1041                                     tp->snd_wnd) {
1042                                         /* We have outstanding data activate a timer */
1043                                         tcp_timer_activate(tp, TT_REXMT,
1044                                             tp->t_rxtcur);
1045                                 }
1046                         }
1047                         break;
1048                 case TT_PERSIST:
1049                         if (tp->t_timers->tt_flags & TT_PERSIST_SUS) {
1050                                 tp->t_timers->tt_flags &= ~TT_PERSIST_SUS;
1051                                 if (tp->snd_wnd == 0) {
1052                                         /* Activate the persists timer */
1053                                         tp->t_rxtshift = 0;
1054                                         tcp_setpersist(tp);
1055                                 }
1056                         }
1057                         break;
1058                 case TT_KEEP:
1059                         if (tp->t_timers->tt_flags & TT_KEEP_SUS) {
1060                                 tp->t_timers->tt_flags &= ~TT_KEEP_SUS;
1061                                 tcp_timer_activate(tp, TT_KEEP,
1062                                             TCPS_HAVEESTABLISHED(tp->t_state) ?
1063                                             TP_KEEPIDLE(tp) : TP_KEEPINIT(tp));
1064                         }
1065                         break;
1066                 case TT_2MSL:
1067                         if (tp->t_timers->tt_flags &= TT_2MSL_SUS) {
1068                                 struct socket *so = tptosocket(tp);
1069
1070                                 tp->t_timers->tt_flags &= ~TT_2MSL_SUS;
1071                                 if ((tp->t_state == TCPS_FIN_WAIT_2) &&
1072                                     (so == NULL ||      /* XXXGL: needed? */
1073                                     (so->so_rcv.sb_state & SBS_CANTRCVMORE))) {
1074                                         /* Star the 2MSL timer */
1075                                         tcp_timer_activate(tp, TT_2MSL,
1076                                             (tcp_fast_finwait2_recycle) ?
1077                                             tcp_finwait2_timeout : TP_MAXIDLE(tp));
1078                                 }
1079                         }
1080                         break;
1081                 default:
1082                         panic("tp:%p bad timer_type 0x%x", tp, timer_type);
1083         }
1084 }
1085
1086 static void
1087 tcp_timer_discard(void *ptp)
1088 {
1089         struct epoch_tracker et;
1090         struct tcpcb *tp = (struct tcpcb *)ptp;
1091         struct inpcb *inp = tptoinpcb(tp);
1092
1093         INP_WLOCK(inp);
1094         CURVNET_SET(inp->inp_vnet);
1095         NET_EPOCH_ENTER(et);
1096
1097         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) != 0,
1098                 ("%s: tcpcb has to be stopped here", __func__));
1099         if (--tp->t_timers->tt_draincnt > 0 ||
1100             tcp_freecb(tp) == false)
1101                 INP_WUNLOCK(inp);
1102         NET_EPOCH_EXIT(et);
1103         CURVNET_RESTORE();
1104 }
1105
1106 void
1107 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
1108 {
1109         struct callout *t_callout;
1110
1111         tp->t_timers->tt_flags |= TT_STOPPED;
1112         switch (timer_type) {
1113                 case TT_DELACK:
1114                         t_callout = &tp->t_timers->tt_delack;
1115                         break;
1116                 case TT_REXMT:
1117                         t_callout = &tp->t_timers->tt_rexmt;
1118                         break;
1119                 case TT_PERSIST:
1120                         t_callout = &tp->t_timers->tt_persist;
1121                         break;
1122                 case TT_KEEP:
1123                         t_callout = &tp->t_timers->tt_keep;
1124                         break;
1125                 case TT_2MSL:
1126                         t_callout = &tp->t_timers->tt_2msl;
1127                         break;
1128                 default:
1129                         if (tp->t_fb->tfb_tcp_timer_stop) {
1130                                 /*
1131                                  * XXXrrs we need to look at this with the
1132                                  * stop case below (flags).
1133                                  */
1134                                 tp->t_fb->tfb_tcp_timer_stop(tp, timer_type);
1135                                 return;
1136                         }
1137                         panic("tp %p bad timer_type %#x", tp, timer_type);
1138                 }
1139
1140         if (callout_async_drain(t_callout, tcp_timer_discard) == 0) {
1141                 /*
1142                  * Can't stop the callout, defer tcpcb actual deletion
1143                  * to the last one. We do this using the async drain
1144                  * function and incrementing the count in
1145                  */
1146                 tp->t_timers->tt_draincnt++;
1147         }
1148 }