sys/netinet/tcp_timer.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  *
  31  *      @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95
  32  */
  33
  34 #include <sys/cdefs.h>
  35 __FBSDID("$FreeBSD$");
  36
  37 #include "opt_inet.h"
  38 #include "opt_inet6.h"
  39 #include "opt_tcpdebug.h"
  40 #include "opt_rss.h"
  41
  42 #include <sys/param.h>
  43 #include <sys/kernel.h>
  44 #include <sys/lock.h>
  45 #include <sys/mbuf.h>
  46 #include <sys/mutex.h>
  47 #include <sys/protosw.h>
  48 #include <sys/smp.h>
  49 #include <sys/socket.h>
  50 #include <sys/socketvar.h>
  51 #include <sys/sysctl.h>
  52 #include <sys/systm.h>
  53
  54 #include <net/if.h>
  55 #include <net/route.h>
  56 #include <net/rss_config.h>
  57 #include <net/vnet.h>
  58 #include <net/netisr.h>
  59
  60 #include <netinet/in.h>
  61 #include <netinet/in_kdtrace.h>
  62 #include <netinet/in_pcb.h>
  63 #include <netinet/in_rss.h>
  64 #include <netinet/in_systm.h>
  65 #ifdef INET6
  66 #include <netinet6/in6_pcb.h>
  67 #endif
  68 #include <netinet/ip_var.h>
  69 #include <netinet/tcp.h>
  70 #include <netinet/tcp_fsm.h>
  71 #include <netinet/tcp_log_buf.h>
  72 #include <netinet/tcp_timer.h>
  73 #include <netinet/tcp_var.h>
  74 #include <netinet/tcp_seq.h>
  75 #include <netinet/cc/cc.h>
  76 #ifdef INET6
  77 #include <netinet6/tcp6_var.h>
  78 #endif
  79 #include <netinet/tcpip.h>
  80 #ifdef TCPDEBUG
  81 #include <netinet/tcp_debug.h>
  82 #endif
  83
  84 int    tcp_persmin;
  85 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmin,
  86     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
  87     &tcp_persmin, 0, sysctl_msec_to_ticks, "I",
  88     "minimum persistence interval");
  89
  90 int    tcp_persmax;
  91 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmax,
  92     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
  93     &tcp_persmax, 0, sysctl_msec_to_ticks, "I",
  94     "maximum persistence interval");
  95
  96 int     tcp_keepinit;
  97 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit,
  98     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
  99     &tcp_keepinit, 0, sysctl_msec_to_ticks, "I",
 100     "time to establish connection");
 101
 102 int     tcp_keepidle;
 103 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle,
 104     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 105     &tcp_keepidle, 0, sysctl_msec_to_ticks, "I",
 106     "time before keepalive probes begin");
 107
 108 int     tcp_keepintvl;
 109 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl,
 110     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 111     &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I",
 112     "time between keepalive probes");
 113
 114 int     tcp_delacktime;
 115 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime,
 116     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 117     &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
 118     "Time before a delayed ACK is sent");
 119
 120 VNET_DEFINE(int, tcp_msl);
 121 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl,
 122     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_VNET,
 123     &VNET_NAME(tcp_msl), 0, sysctl_msec_to_ticks, "I",
 124     "Maximum segment lifetime");
 125
 126 int     tcp_rexmit_initial;
 127 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_initial,
 128    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 129     &tcp_rexmit_initial, 0, sysctl_msec_to_ticks, "I",
 130     "Initial Retransmission Timeout");
 131
 132 int     tcp_rexmit_min;
 133 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min,
 134     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 135     &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
 136     "Minimum Retransmission Timeout");
 137
 138 int     tcp_rexmit_slop;
 139 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop,
 140     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 141     &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
 142     "Retransmission Timer Slop");
 143
 144 VNET_DEFINE(int, tcp_always_keepalive) = 1;
 145 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_VNET|CTLFLAG_RW,
 146     &VNET_NAME(tcp_always_keepalive) , 0,
 147     "Assume SO_KEEPALIVE on all TCP connections");
 148
 149 int    tcp_fast_finwait2_recycle = 0;
 150 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
 151     &tcp_fast_finwait2_recycle, 0,
 152     "Recycle closed FIN_WAIT_2 connections faster");
 153
 154 int    tcp_finwait2_timeout;
 155 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout,
 156     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
 157     &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I",
 158     "FIN-WAIT2 timeout");
 159
 160 int     tcp_keepcnt = TCPTV_KEEPCNT;
 161 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
 162     "Number of keepalive probes to send");
 163
 164         /* max idle probes */
 165 int     tcp_maxpersistidle;
 166
 167 int     tcp_rexmit_drop_options = 0;
 168 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
 169     &tcp_rexmit_drop_options, 0,
 170     "Drop TCP options from 3rd and later retransmitted SYN");
 171
 172 VNET_DEFINE(int, tcp_pmtud_blackhole_detect);
 173 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection,
 174     CTLFLAG_RW|CTLFLAG_VNET,
 175     &VNET_NAME(tcp_pmtud_blackhole_detect), 0,
 176     "Path MTU Discovery Black Hole Detection Enabled");
 177
 178 #ifdef INET
 179 VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200;
 180 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss,
 181     CTLFLAG_RW|CTLFLAG_VNET,
 182     &VNET_NAME(tcp_pmtud_blackhole_mss), 0,
 183     "Path MTU Discovery Black Hole Detection lowered MSS");
 184 #endif
 185
 186 #ifdef INET6
 187 VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220;
 188 SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss,
 189     CTLFLAG_RW|CTLFLAG_VNET,
 190     &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0,
 191     "Path MTU Discovery IPv6 Black Hole Detection lowered MSS");
 192 #endif
 193
 194 #ifdef  RSS
 195 static int      per_cpu_timers = 1;
 196 #else
 197 static int      per_cpu_timers = 0;
 198 #endif
 199 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
 200     &per_cpu_timers , 0, "run tcp timers on all cpus");
 201
 202 /*
 203  * Map the given inp to a CPU id.
 204  *
 205  * This queries RSS if it's compiled in, else it defaults to the current
 206  * CPU ID.
 207  */
 208 inline int
 209 inp_to_cpuid(struct inpcb *inp)
 210 {
 211         u_int cpuid;
 212
 213         if (per_cpu_timers) {
 214 #ifdef  RSS
 215                 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
 216                 if (cpuid == NETISR_CPUID_NONE)
 217                         return (curcpu);        /* XXX */
 218                 else
 219                         return (cpuid);
 220 #endif
 221                 /*
 222                  * We don't have a flowid -> cpuid mapping, so cheat and
 223                  * just map unknown cpuids to curcpu.  Not the best, but
 224                  * apparently better than defaulting to swi 0.
 225                  */
 226                 cpuid = inp->inp_flowid % (mp_maxid + 1);
 227                 if (! CPU_ABSENT(cpuid))
 228                         return (cpuid);
 229                 return (curcpu);
 230         } else {
 231                 return (0);
 232         }
 233 }
 234
 235 /*
 236  * Tcp protocol timeout routine called every 500 ms.
 237  * Updates timestamps used for TCP
 238  * causes finite state machine actions if timers expire.
 239  */
 240 void
 241 tcp_slowtimo(void)
 242 {
 243         VNET_ITERATOR_DECL(vnet_iter);
 244
 245         VNET_LIST_RLOCK_NOSLEEP();
 246         VNET_FOREACH(vnet_iter) {
 247                 CURVNET_SET(vnet_iter);
 248                 (void) tcp_tw_2msl_scan(0);
 249                 CURVNET_RESTORE();
 250         }
 251         VNET_LIST_RUNLOCK_NOSLEEP();
 252 }
 253
 254 int     tcp_backoff[TCP_MAXRXTSHIFT + 1] =
 255     { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
 256
 257 int tcp_totbackoff = 2559;      /* sum of tcp_backoff[] */
 258
 259 /*
 260  * TCP timer processing.
 261  */
 262
 263 void
 264 tcp_timer_delack(void *xtp)
 265 {
 266         struct epoch_tracker et;
 267         struct tcpcb *tp = xtp;
 268         struct inpcb *inp;
 269         CURVNET_SET(tp->t_vnet);
 270
 271         inp = tp->t_inpcb;
 272         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 273         INP_WLOCK(inp);
 274         if (callout_pending(&tp->t_timers->tt_delack) ||
 275             !callout_active(&tp->t_timers->tt_delack)) {
 276                 INP_WUNLOCK(inp);
 277                 CURVNET_RESTORE();
 278                 return;
 279         }
 280         callout_deactivate(&tp->t_timers->tt_delack);
 281         if ((inp->inp_flags & INP_DROPPED) != 0) {
 282                 INP_WUNLOCK(inp);
 283                 CURVNET_RESTORE();
 284                 return;
 285         }
 286         tp->t_flags |= TF_ACKNOW;
 287         TCPSTAT_INC(tcps_delack);
 288         NET_EPOCH_ENTER(et);
 289         (void) tcp_output_unlock(tp);
 290         NET_EPOCH_EXIT(et);
 291         CURVNET_RESTORE();
 292 }
 293
 294 void
 295 tcp_inpinfo_lock_del(struct inpcb *inp, struct tcpcb *tp)
 296 {
 297         if (inp && tp != NULL)
 298                 INP_WUNLOCK(inp);
 299 }
 300
 301 void
 302 tcp_timer_2msl(void *xtp)
 303 {
 304         struct tcpcb *tp = xtp;
 305         struct inpcb *inp;
 306         struct epoch_tracker et;
 307         CURVNET_SET(tp->t_vnet);
 308 #ifdef TCPDEBUG
 309         int ostate;
 310
 311         ostate = tp->t_state;
 312 #endif
 313         inp = tp->t_inpcb;
 314         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 315         INP_WLOCK(inp);
 316         tcp_free_sackholes(tp);
 317         if (callout_pending(&tp->t_timers->tt_2msl) ||
 318             !callout_active(&tp->t_timers->tt_2msl)) {
 319                 INP_WUNLOCK(tp->t_inpcb);
 320                 CURVNET_RESTORE();
 321                 return;
 322         }
 323         callout_deactivate(&tp->t_timers->tt_2msl);
 324         if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 325                 INP_WUNLOCK(inp);
 326                 CURVNET_RESTORE();
 327                 return;
 328         }
 329         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 330                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 331         /*
 332          * 2 MSL timeout in shutdown went off.  If we're closed but
 333          * still waiting for peer to close and connection has been idle
 334          * too long delete connection control block.  Otherwise, check
 335          * again in a bit.
 336          *
 337          * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
 338          * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
 339          * Ignore fact that there were recent incoming segments.
 340          */
 341         if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
 342             tp->t_inpcb && tp->t_inpcb->inp_socket &&
 343             (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
 344                 TCPSTAT_INC(tcps_finwait2_drops);
 345                 NET_EPOCH_ENTER(et);
 346                 tp = tcp_close(tp);
 347                 NET_EPOCH_EXIT(et);
 348                 tcp_inpinfo_lock_del(inp, tp);
 349                 goto out;
 350         } else {
 351                 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) {
 352                         callout_reset(&tp->t_timers->tt_2msl,
 353                                       TP_KEEPINTVL(tp), tcp_timer_2msl, tp);
 354                 } else {
 355                         NET_EPOCH_ENTER(et);
 356                         tp = tcp_close(tp);
 357                         NET_EPOCH_EXIT(et);
 358                         tcp_inpinfo_lock_del(inp, tp);
 359                         goto out;
 360                 }
 361         }
 362
 363 #ifdef TCPDEBUG
 364         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 365                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 366                           PRU_SLOWTIMO);
 367 #endif
 368         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 369
 370         if (tp != NULL)
 371                 INP_WUNLOCK(inp);
 372 out:
 373         CURVNET_RESTORE();
 374 }
 375
 376 void
 377 tcp_timer_keep(void *xtp)
 378 {
 379         struct tcpcb *tp = xtp;
 380         struct tcptemp *t_template;
 381         struct inpcb *inp;
 382         struct epoch_tracker et;
 383         CURVNET_SET(tp->t_vnet);
 384 #ifdef TCPDEBUG
 385         int ostate;
 386
 387         ostate = tp->t_state;
 388 #endif
 389         inp = tp->t_inpcb;
 390         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 391         INP_WLOCK(inp);
 392         if (callout_pending(&tp->t_timers->tt_keep) ||
 393             !callout_active(&tp->t_timers->tt_keep)) {
 394                 INP_WUNLOCK(inp);
 395                 CURVNET_RESTORE();
 396                 return;
 397         }
 398         callout_deactivate(&tp->t_timers->tt_keep);
 399         if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 400                 INP_WUNLOCK(inp);
 401                 CURVNET_RESTORE();
 402                 return;
 403         }
 404         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 405                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 406
 407         /*
 408          * Because we don't regularly reset the keepalive callout in
 409          * the ESTABLISHED state, it may be that we don't actually need
 410          * to send a keepalive yet. If that occurs, schedule another
 411          * call for the next time the keepalive timer might expire.
 412          */
 413         if (TCPS_HAVEESTABLISHED(tp->t_state)) {
 414                 u_int idletime;
 415
 416                 idletime = ticks - tp->t_rcvtime;
 417                 if (idletime < TP_KEEPIDLE(tp)) {
 418                         callout_reset(&tp->t_timers->tt_keep,
 419                             TP_KEEPIDLE(tp) - idletime, tcp_timer_keep, tp);
 420                         INP_WUNLOCK(inp);
 421                         CURVNET_RESTORE();
 422                         return;
 423                 }
 424         }
 425
 426         /*
 427          * Keep-alive timer went off; send something
 428          * or drop connection if idle for too long.
 429          */
 430         TCPSTAT_INC(tcps_keeptimeo);
 431         if (tp->t_state < TCPS_ESTABLISHED)
 432                 goto dropit;
 433         if ((V_tcp_always_keepalive ||
 434             inp->inp_socket->so_options & SO_KEEPALIVE) &&
 435             tp->t_state <= TCPS_CLOSING) {
 436                 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
 437                         goto dropit;
 438                 /*
 439                  * Send a packet designed to force a response
 440                  * if the peer is up and reachable:
 441                  * either an ACK if the connection is still alive,
 442                  * or an RST if the peer has closed the connection
 443                  * due to timeout or reboot.
 444                  * Using sequence number tp->snd_una-1
 445                  * causes the transmitted zero-length segment
 446                  * to lie outside the receive window;
 447                  * by the protocol spec, this requires the
 448                  * correspondent TCP to respond.
 449                  */
 450                 TCPSTAT_INC(tcps_keepprobe);
 451                 t_template = tcpip_maketemplate(inp);
 452                 if (t_template) {
 453                         NET_EPOCH_ENTER(et);
 454                         tcp_respond(tp, t_template->tt_ipgen,
 455                                     &t_template->tt_t, (struct mbuf *)NULL,
 456                                     tp->rcv_nxt, tp->snd_una - 1, 0);
 457                         NET_EPOCH_EXIT(et);
 458                         free(t_template, M_TEMP);
 459                 }
 460                 callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
 461                               tcp_timer_keep, tp);
 462         } else
 463                 callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
 464                               tcp_timer_keep, tp);
 465
 466 #ifdef TCPDEBUG
 467         if (inp->inp_socket->so_options & SO_DEBUG)
 468                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 469                           PRU_SLOWTIMO);
 470 #endif
 471         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 472         INP_WUNLOCK(inp);
 473         CURVNET_RESTORE();
 474         return;
 475
 476 dropit:
 477         TCPSTAT_INC(tcps_keepdrops);
 478         NET_EPOCH_ENTER(et);
 479         tp = tcp_drop(tp, ETIMEDOUT);
 480
 481 #ifdef TCPDEBUG
 482         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 483                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 484                           PRU_SLOWTIMO);
 485 #endif
 486         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 487         NET_EPOCH_EXIT(et);
 488         tcp_inpinfo_lock_del(inp, tp);
 489         CURVNET_RESTORE();
 490 }
 491
 492 void
 493 tcp_timer_persist(void *xtp)
 494 {
 495         struct tcpcb *tp = xtp;
 496         struct inpcb *inp;
 497         struct epoch_tracker et;
 498         int outrv;
 499         CURVNET_SET(tp->t_vnet);
 500 #ifdef TCPDEBUG
 501         int ostate;
 502
 503         ostate = tp->t_state;
 504 #endif
 505         inp = tp->t_inpcb;
 506         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 507         INP_WLOCK(inp);
 508         if (callout_pending(&tp->t_timers->tt_persist) ||
 509             !callout_active(&tp->t_timers->tt_persist)) {
 510                 INP_WUNLOCK(inp);
 511                 CURVNET_RESTORE();
 512                 return;
 513         }
 514         callout_deactivate(&tp->t_timers->tt_persist);
 515         if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 516                 INP_WUNLOCK(inp);
 517                 CURVNET_RESTORE();
 518                 return;
 519         }
 520         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 521                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 522         /*
 523          * Persistence timer into zero window.
 524          * Force a byte to be output, if possible.
 525          */
 526         TCPSTAT_INC(tcps_persisttimeo);
 527         /*
 528          * Hack: if the peer is dead/unreachable, we do not
 529          * time out if the window is closed.  After a full
 530          * backoff, drop the connection if the idle time
 531          * (no responses to probes) reaches the maximum
 532          * backoff that we would use if retransmitting.
 533          */
 534         if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
 535             (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
 536              ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
 537                 TCPSTAT_INC(tcps_persistdrop);
 538                 NET_EPOCH_ENTER(et);
 539                 tp = tcp_drop(tp, ETIMEDOUT);
 540                 NET_EPOCH_EXIT(et);
 541                 tcp_inpinfo_lock_del(inp, tp);
 542                 goto out;
 543         }
 544         /*
 545          * If the user has closed the socket then drop a persisting
 546          * connection after a much reduced timeout.
 547          */
 548         if (tp->t_state > TCPS_CLOSE_WAIT &&
 549             (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
 550                 TCPSTAT_INC(tcps_persistdrop);
 551                 NET_EPOCH_ENTER(et);
 552                 tp = tcp_drop(tp, ETIMEDOUT);
 553                 NET_EPOCH_EXIT(et);
 554                 tcp_inpinfo_lock_del(inp, tp);
 555                 goto out;
 556         }
 557         tcp_setpersist(tp);
 558         tp->t_flags |= TF_FORCEDATA;
 559         NET_EPOCH_ENTER(et);
 560         outrv = tcp_output_nodrop(tp);
 561         tp->t_flags &= ~TF_FORCEDATA;
 562
 563 #ifdef TCPDEBUG
 564         if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
 565                 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
 566 #endif
 567         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 568         (void) tcp_unlock_or_drop(tp, outrv);
 569         NET_EPOCH_EXIT(et);
 570 out:
 571         CURVNET_RESTORE();
 572 }
 573
 574 void
 575 tcp_timer_rexmt(void * xtp)
 576 {
 577         struct tcpcb *tp = xtp;
 578         CURVNET_SET(tp->t_vnet);
 579         int rexmt, outrv;
 580         struct inpcb *inp;
 581         struct epoch_tracker et;
 582         bool isipv6;
 583 #ifdef TCPDEBUG
 584         int ostate;
 585
 586         ostate = tp->t_state;
 587 #endif
 588         inp = tp->t_inpcb;
 589         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 590         INP_WLOCK(inp);
 591         if (callout_pending(&tp->t_timers->tt_rexmt) ||
 592             !callout_active(&tp->t_timers->tt_rexmt)) {
 593                 INP_WUNLOCK(inp);
 594                 CURVNET_RESTORE();
 595                 return;
 596         }
 597         callout_deactivate(&tp->t_timers->tt_rexmt);
 598         if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 599                 INP_WUNLOCK(inp);
 600                 CURVNET_RESTORE();
 601                 return;
 602         }
 603         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 604                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 605         tcp_free_sackholes(tp);
 606         TCP_LOG_EVENT(tp, NULL, NULL, NULL, TCP_LOG_RTO, 0, 0, NULL, false);
 607         if (tp->t_fb->tfb_tcp_rexmit_tmr) {
 608                 /* The stack has a timer action too. */
 609                 (*tp->t_fb->tfb_tcp_rexmit_tmr)(tp);
 610         }
 611         /*
 612          * Retransmission timer went off.  Message has not
 613          * been acked within retransmit interval.  Back off
 614          * to a longer retransmit interval and retransmit one segment.
 615          */
 616         if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
 617                 tp->t_rxtshift = TCP_MAXRXTSHIFT;
 618                 TCPSTAT_INC(tcps_timeoutdrop);
 619                 NET_EPOCH_ENTER(et);
 620                 tp = tcp_drop(tp, ETIMEDOUT);
 621                 NET_EPOCH_EXIT(et);
 622                 tcp_inpinfo_lock_del(inp, tp);
 623                 goto out;
 624         }
 625         if (tp->t_state == TCPS_SYN_SENT) {
 626                 /*
 627                  * If the SYN was retransmitted, indicate CWND to be
 628                  * limited to 1 segment in cc_conn_init().
 629                  */
 630                 tp->snd_cwnd = 1;
 631         } else if (tp->t_rxtshift == 1) {
 632                 /*
 633                  * first retransmit; record ssthresh and cwnd so they can
 634                  * be recovered if this turns out to be a "bad" retransmit.
 635                  * A retransmit is considered "bad" if an ACK for this
 636                  * segment is received within RTT/2 interval; the assumption
 637                  * here is that the ACK was already in flight.  See
 638                  * "On Estimating End-to-End Network Path Properties" by
 639                  * Allman and Paxson for more details.
 640                  */
 641                 tp->snd_cwnd_prev = tp->snd_cwnd;
 642                 tp->snd_ssthresh_prev = tp->snd_ssthresh;
 643                 tp->snd_recover_prev = tp->snd_recover;
 644                 if (IN_FASTRECOVERY(tp->t_flags))
 645                         tp->t_flags |= TF_WASFRECOVERY;
 646                 else
 647                         tp->t_flags &= ~TF_WASFRECOVERY;
 648                 if (IN_CONGRECOVERY(tp->t_flags))
 649                         tp->t_flags |= TF_WASCRECOVERY;
 650                 else
 651                         tp->t_flags &= ~TF_WASCRECOVERY;
 652                 if ((tp->t_flags & TF_RCVD_TSTMP) == 0)
 653                         tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
 654                 /* In the event that we've negotiated timestamps
 655                  * badrxtwin will be set to the value that we set
 656                  * the retransmitted packet's to_tsval to by tcp_output
 657                  */
 658                 tp->t_flags |= TF_PREVVALID;
 659         } else
 660                 tp->t_flags &= ~TF_PREVVALID;
 661         TCPSTAT_INC(tcps_rexmttimeo);
 662         if ((tp->t_state == TCPS_SYN_SENT) ||
 663             (tp->t_state == TCPS_SYN_RECEIVED))
 664                 rexmt = tcp_rexmit_initial * tcp_backoff[tp->t_rxtshift];
 665         else
 666                 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
 667         TCPT_RANGESET(tp->t_rxtcur, rexmt,
 668                       tp->t_rttmin, TCPTV_REXMTMAX);
 669
 670         /*
 671          * We enter the path for PLMTUD if connection is established or, if
 672          * connection is FIN_WAIT_1 status, reason for the last is that if
 673          * amount of data we send is very small, we could send it in couple of
 674          * packets and process straight to FIN. In that case we won't catch
 675          * ESTABLISHED state.
 676          */
 677 #ifdef INET6
 678         isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? true : false;
 679 #else
 680         isipv6 = false;
 681 #endif
 682         if (((V_tcp_pmtud_blackhole_detect == 1) ||
 683             (V_tcp_pmtud_blackhole_detect == 2 && !isipv6) ||
 684             (V_tcp_pmtud_blackhole_detect == 3 && isipv6)) &&
 685             ((tp->t_state == TCPS_ESTABLISHED) ||
 686             (tp->t_state == TCPS_FIN_WAIT_1))) {
 687                 if (tp->t_rxtshift == 1) {
 688                         /*
 689                          * We enter blackhole detection after the first
 690                          * unsuccessful timer based retransmission.
 691                          * Then we reduce up to two times the MSS, each
 692                          * candidate giving two tries of retransmissions.
 693                          * But we give a candidate only two tries, if it
 694                          * actually reduces the MSS.
 695                          */
 696                         tp->t_blackhole_enter = 2;
 697                         tp->t_blackhole_exit = tp->t_blackhole_enter;
 698                         if (isipv6) {
 699 #ifdef INET6
 700                                 if (tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss)
 701                                         tp->t_blackhole_exit += 2;
 702                                 if (tp->t_maxseg > V_tcp_v6mssdflt &&
 703                                     V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt)
 704                                         tp->t_blackhole_exit += 2;
 705 #endif
 706                         } else {
 707 #ifdef INET
 708                                 if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss)
 709                                         tp->t_blackhole_exit += 2;
 710                                 if (tp->t_maxseg > V_tcp_mssdflt &&
 711                                     V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt)
 712                                         tp->t_blackhole_exit += 2;
 713 #endif
 714                         }
 715                 }
 716                 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
 717                     (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
 718                     (tp->t_rxtshift >= tp->t_blackhole_enter &&
 719                     tp->t_rxtshift < tp->t_blackhole_exit &&
 720                     (tp->t_rxtshift - tp->t_blackhole_enter) % 2 == 0)) {
 721                         /*
 722                          * Enter Path MTU Black-hole Detection mechanism:
 723                          * - Disable Path MTU Discovery (IP "DF" bit).
 724                          * - Reduce MTU to lower value than what we
 725                          *   negotiated with peer.
 726                          */
 727                         if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) == 0) {
 728                                 /* Record that we may have found a black hole. */
 729                                 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
 730                                 /* Keep track of previous MSS. */
 731                                 tp->t_pmtud_saved_maxseg = tp->t_maxseg;
 732                         }
 733
 734                         /*
 735                          * Reduce the MSS to blackhole value or to the default
 736                          * in an attempt to retransmit.
 737                          */
 738 #ifdef INET6
 739                         if (isipv6 &&
 740                             tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss &&
 741                             V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt) {
 742                                 /* Use the sysctl tuneable blackhole MSS. */
 743                                 tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss;
 744                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
 745                         } else if (isipv6) {
 746                                 /* Use the default MSS. */
 747                                 tp->t_maxseg = V_tcp_v6mssdflt;
 748                                 /*
 749                                  * Disable Path MTU Discovery when we switch to
 750                                  * minmss.
 751                                  */
 752                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 753                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
 754                         }
 755 #endif
 756 #if defined(INET6) && defined(INET)
 757                         else
 758 #endif
 759 #ifdef INET
 760                         if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss &&
 761                             V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt) {
 762                                 /* Use the sysctl tuneable blackhole MSS. */
 763                                 tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
 764                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
 765                         } else {
 766                                 /* Use the default MSS. */
 767                                 tp->t_maxseg = V_tcp_mssdflt;
 768                                 /*
 769                                  * Disable Path MTU Discovery when we switch to
 770                                  * minmss.
 771                                  */
 772                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 773                                 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
 774                         }
 775 #endif
 776                         /*
 777                          * Reset the slow-start flight size
 778                          * as it may depend on the new MSS.
 779                          */
 780                         if (CC_ALGO(tp)->conn_init != NULL)
 781                                 CC_ALGO(tp)->conn_init(tp->ccv);
 782                 } else {
 783                         /*
 784                          * If further retransmissions are still unsuccessful
 785                          * with a lowered MTU, maybe this isn't a blackhole and
 786                          * we restore the previous MSS and blackhole detection
 787                          * flags.
 788                          */
 789                         if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
 790                             (tp->t_rxtshift >= tp->t_blackhole_exit)) {
 791                                 tp->t_flags2 |= TF2_PLPMTU_PMTUD;
 792                                 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
 793                                 tp->t_maxseg = tp->t_pmtud_saved_maxseg;
 794                                 TCPSTAT_INC(tcps_pmtud_blackhole_failed);
 795                                 /*
 796                                  * Reset the slow-start flight size as it
 797                                  * may depend on the new MSS.
 798                                  */
 799                                 if (CC_ALGO(tp)->conn_init != NULL)
 800                                         CC_ALGO(tp)->conn_init(tp->ccv);
 801                         }
 802                 }
 803         }
 804
 805         /*
 806          * Disable RFC1323 and SACK if we haven't got any response to
 807          * our third SYN to work-around some broken terminal servers
 808          * (most of which have hopefully been retired) that have bad VJ
 809          * header compression code which trashes TCP segments containing
 810          * unknown-to-them TCP options.
 811          */
 812         if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
 813             (tp->t_rxtshift == 3))
 814                 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
 815         /*
 816          * If we backed off this far, notify the L3 protocol that we're having
 817          * connection problems.
 818          */
 819         if (tp->t_rxtshift > TCP_RTT_INVALIDATE) {
 820 #ifdef INET6
 821                 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
 822                         in6_losing(tp->t_inpcb);
 823                 else
 824 #endif
 825                         in_losing(tp->t_inpcb);
 826         }
 827         tp->snd_nxt = tp->snd_una;
 828         tp->snd_recover = tp->snd_max;
 829         /*
 830          * Force a segment to be sent.
 831          */
 832         tp->t_flags |= TF_ACKNOW;
 833         /*
 834          * If timing a segment in this window, stop the timer.
 835          */
 836         tp->t_rtttime = 0;
 837
 838         cc_cong_signal(tp, NULL, CC_RTO);
 839         NET_EPOCH_ENTER(et);
 840         outrv = tcp_output_nodrop(tp);
 841 #ifdef TCPDEBUG
 842         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 843                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 844                           PRU_SLOWTIMO);
 845 #endif
 846         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 847         (void) tcp_unlock_or_drop(tp, outrv);
 848         NET_EPOCH_EXIT(et);
 849 out:
 850         CURVNET_RESTORE();
 851 }
 852
 853 void
 854 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
 855 {
 856         struct callout *t_callout;
 857         callout_func_t *f_callout;
 858         struct inpcb *inp = tp->t_inpcb;
 859         int cpu = inp_to_cpuid(inp);
 860
 861 #ifdef TCP_OFFLOAD
 862         if (tp->t_flags & TF_TOE)
 863                 return;
 864 #endif
 865
 866         if (tp->t_timers->tt_flags & TT_STOPPED)
 867                 return;
 868
 869         switch (timer_type) {
 870                 case TT_DELACK:
 871                         t_callout = &tp->t_timers->tt_delack;
 872                         f_callout = tcp_timer_delack;
 873                         break;
 874                 case TT_REXMT:
 875                         t_callout = &tp->t_timers->tt_rexmt;
 876                         f_callout = tcp_timer_rexmt;
 877                         break;
 878                 case TT_PERSIST:
 879                         t_callout = &tp->t_timers->tt_persist;
 880                         f_callout = tcp_timer_persist;
 881                         break;
 882                 case TT_KEEP:
 883                         t_callout = &tp->t_timers->tt_keep;
 884                         f_callout = tcp_timer_keep;
 885                         break;
 886                 case TT_2MSL:
 887                         t_callout = &tp->t_timers->tt_2msl;
 888                         f_callout = tcp_timer_2msl;
 889                         break;
 890                 default:
 891                         if (tp->t_fb->tfb_tcp_timer_activate) {
 892                                 tp->t_fb->tfb_tcp_timer_activate(tp, timer_type, delta);
 893                                 return;
 894                         }
 895                         panic("tp %p bad timer_type %#x", tp, timer_type);
 896                 }
 897         if (delta == 0) {
 898                 callout_stop(t_callout);
 899         } else {
 900                 callout_reset_on(t_callout, delta, f_callout, tp, cpu);
 901         }
 902 }
 903
 904 int
 905 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type)
 906 {
 907         struct callout *t_callout;
 908
 909         switch (timer_type) {
 910                 case TT_DELACK:
 911                         t_callout = &tp->t_timers->tt_delack;
 912                         break;
 913                 case TT_REXMT:
 914                         t_callout = &tp->t_timers->tt_rexmt;
 915                         break;
 916                 case TT_PERSIST:
 917                         t_callout = &tp->t_timers->tt_persist;
 918                         break;
 919                 case TT_KEEP:
 920                         t_callout = &tp->t_timers->tt_keep;
 921                         break;
 922                 case TT_2MSL:
 923                         t_callout = &tp->t_timers->tt_2msl;
 924                         break;
 925                 default:
 926                         if (tp->t_fb->tfb_tcp_timer_active) {
 927                                 return(tp->t_fb->tfb_tcp_timer_active(tp, timer_type));
 928                         }
 929                         panic("tp %p bad timer_type %#x", tp, timer_type);
 930                 }
 931         return callout_active(t_callout);
 932 }
 933
 934 /*
 935  * Stop the timer from running, and apply a flag
 936  * against the timer_flags that will force the
 937  * timer never to run. The flag is needed to assure
 938  * a race does not leave it running and cause
 939  * the timer to possibly restart itself (keep and persist
 940  * especially do this).
 941  */
 942 int
 943 tcp_timer_suspend(struct tcpcb *tp, uint32_t timer_type)
 944 {
 945         struct callout *t_callout;
 946         uint32_t t_flags;
 947
 948         switch (timer_type) {
 949                 case TT_DELACK:
 950                         t_flags = TT_DELACK_SUS;
 951                         t_callout = &tp->t_timers->tt_delack;
 952                         break;
 953                 case TT_REXMT:
 954                         t_flags = TT_REXMT_SUS;
 955                         t_callout = &tp->t_timers->tt_rexmt;
 956                         break;
 957                 case TT_PERSIST:
 958                         t_flags = TT_PERSIST_SUS;
 959                         t_callout = &tp->t_timers->tt_persist;
 960                         break;
 961                 case TT_KEEP:
 962                         t_flags = TT_KEEP_SUS;
 963                         t_callout = &tp->t_timers->tt_keep;
 964                         break;
 965                 case TT_2MSL:
 966                         t_flags = TT_2MSL_SUS;
 967                         t_callout = &tp->t_timers->tt_2msl;
 968                         break;
 969                 default:
 970                         panic("tp:%p bad timer_type 0x%x", tp, timer_type);
 971         }
 972         tp->t_timers->tt_flags |= t_flags;
 973         return (callout_stop(t_callout));
 974 }
 975
 976 void
 977 tcp_timers_unsuspend(struct tcpcb *tp, uint32_t timer_type)
 978 {
 979         switch (timer_type) {
 980                 case TT_DELACK:
 981                         if (tp->t_timers->tt_flags & TT_DELACK_SUS) {
 982                                 tp->t_timers->tt_flags &= ~TT_DELACK_SUS;
 983                                 if (tp->t_flags & TF_DELACK) {
 984                                         /* Delayed ack timer should be up activate a timer */
 985                                         tp->t_flags &= ~TF_DELACK;
 986                                         tcp_timer_activate(tp, TT_DELACK,
 987                                             tcp_delacktime);
 988                                 }
 989                         }
 990                         break;
 991                 case TT_REXMT:
 992                         if (tp->t_timers->tt_flags & TT_REXMT_SUS) {
 993                                 tp->t_timers->tt_flags &= ~TT_REXMT_SUS;
 994                                 if (SEQ_GT(tp->snd_max, tp->snd_una) &&
 995                                     (tcp_timer_active((tp), TT_PERSIST) == 0) &&
 996                                     tp->snd_wnd) {
 997                                         /* We have outstanding data activate a timer */
 998                                         tcp_timer_activate(tp, TT_REXMT,
 999                                             tp->t_rxtcur);
1000                                 }
1001                         }
1002                         break;
1003                 case TT_PERSIST:
1004                         if (tp->t_timers->tt_flags & TT_PERSIST_SUS) {
1005                                 tp->t_timers->tt_flags &= ~TT_PERSIST_SUS;
1006                                 if (tp->snd_wnd == 0) {
1007                                         /* Activate the persists timer */
1008                                         tp->t_rxtshift = 0;
1009                                         tcp_setpersist(tp);
1010                                 }
1011                         }
1012                         break;
1013                 case TT_KEEP:
1014                         if (tp->t_timers->tt_flags & TT_KEEP_SUS) {
1015                                 tp->t_timers->tt_flags &= ~TT_KEEP_SUS;
1016                                 tcp_timer_activate(tp, TT_KEEP,
1017                                             TCPS_HAVEESTABLISHED(tp->t_state) ?
1018                                             TP_KEEPIDLE(tp) : TP_KEEPINIT(tp));
1019                         }
1020                         break;
1021                 case TT_2MSL:
1022                         if (tp->t_timers->tt_flags &= TT_2MSL_SUS) {
1023                                 tp->t_timers->tt_flags &= ~TT_2MSL_SUS;
1024                                 if ((tp->t_state == TCPS_FIN_WAIT_2) &&
1025                                     ((tp->t_inpcb->inp_socket == NULL) ||
1026                                      (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE))) {
1027                                         /* Star the 2MSL timer */
1028                                         tcp_timer_activate(tp, TT_2MSL,
1029                                             (tcp_fast_finwait2_recycle) ?
1030                                             tcp_finwait2_timeout : TP_MAXIDLE(tp));
1031                                 }
1032                         }
1033                         break;
1034                 default:
1035                         panic("tp:%p bad timer_type 0x%x", tp, timer_type);
1036         }
1037 }
1038
1039 static void
1040 tcp_timer_discard(void *ptp)
1041 {
1042         struct inpcb *inp;
1043         struct tcpcb *tp;
1044         struct epoch_tracker et;
1045
1046         tp = (struct tcpcb *)ptp;
1047         CURVNET_SET(tp->t_vnet);
1048         NET_EPOCH_ENTER(et);
1049         inp = tp->t_inpcb;
1050         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL",
1051                 __func__, tp));
1052         INP_WLOCK(inp);
1053         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) != 0,
1054                 ("%s: tcpcb has to be stopped here", __func__));
1055         if (--tp->t_timers->tt_draincnt > 0 ||
1056             tcp_freecb(tp) == false)
1057                 INP_WUNLOCK(inp);
1058         NET_EPOCH_EXIT(et);
1059         CURVNET_RESTORE();
1060 }
1061
1062 void
1063 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
1064 {
1065         struct callout *t_callout;
1066
1067         tp->t_timers->tt_flags |= TT_STOPPED;
1068         switch (timer_type) {
1069                 case TT_DELACK:
1070                         t_callout = &tp->t_timers->tt_delack;
1071                         break;
1072                 case TT_REXMT:
1073                         t_callout = &tp->t_timers->tt_rexmt;
1074                         break;
1075                 case TT_PERSIST:
1076                         t_callout = &tp->t_timers->tt_persist;
1077                         break;
1078                 case TT_KEEP:
1079                         t_callout = &tp->t_timers->tt_keep;
1080                         break;
1081                 case TT_2MSL:
1082                         t_callout = &tp->t_timers->tt_2msl;
1083                         break;
1084                 default:
1085                         if (tp->t_fb->tfb_tcp_timer_stop) {
1086                                 /*
1087                                  * XXXrrs we need to look at this with the
1088                                  * stop case below (flags).
1089                                  */
1090                                 tp->t_fb->tfb_tcp_timer_stop(tp, timer_type);
1091                                 return;
1092                         }
1093                         panic("tp %p bad timer_type %#x", tp, timer_type);
1094                 }
1095
1096         if (callout_async_drain(t_callout, tcp_timer_discard) == 0) {
1097                 /*
1098                  * Can't stop the callout, defer tcpcb actual deletion
1099                  * to the last one. We do this using the async drain
1100                  * function and incrementing the count in
1101                  */
1102                 tp->t_timers->tt_draincnt++;
1103         }
1104 }