sys/netinet/tcp_timer.c

   1 /*-
   2  * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  *      @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95
  30  */
  31
  32 #include <sys/cdefs.h>
  33 __FBSDID("$FreeBSD$");
  34
  35 #include "opt_inet.h"
  36 #include "opt_inet6.h"
  37 #include "opt_tcpdebug.h"
  38 #include "opt_rss.h"
  39
  40 #include <sys/param.h>
  41 #include <sys/kernel.h>
  42 #include <sys/lock.h>
  43 #include <sys/mbuf.h>
  44 #include <sys/mutex.h>
  45 #include <sys/protosw.h>
  46 #include <sys/smp.h>
  47 #include <sys/socket.h>
  48 #include <sys/socketvar.h>
  49 #include <sys/sysctl.h>
  50 #include <sys/systm.h>
  51
  52 #include <net/if.h>
  53 #include <net/route.h>
  54 #include <net/vnet.h>
  55 #include <net/netisr.h>
  56
  57 #include <netinet/cc.h>
  58 #include <netinet/in.h>
  59 #include <netinet/in_pcb.h>
  60 #include <netinet/in_rss.h>
  61 #include <netinet/in_systm.h>
  62 #ifdef INET6
  63 #include <netinet6/in6_pcb.h>
  64 #endif
  65 #include <netinet/ip_var.h>
  66 #include <netinet/tcp_fsm.h>
  67 #include <netinet/tcp_timer.h>
  68 #include <netinet/tcp_var.h>
  69 #include <netinet/tcpip.h>
  70 #ifdef TCPDEBUG
  71 #include <netinet/tcp_debug.h>
  72 #endif
  73
  74 int     tcp_keepinit;
  75 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
  76     &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "time to establish connection");
  77
  78 int     tcp_keepidle;
  79 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
  80     &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "time before keepalive probes begin");
  81
  82 int     tcp_keepintvl;
  83 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
  84     &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "time between keepalive probes");
  85
  86 int     tcp_delacktime;
  87 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW,
  88     &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
  89     "Time before a delayed ACK is sent");
  90
  91 int     tcp_msl;
  92 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
  93     &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
  94
  95 int     tcp_rexmit_min;
  96 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
  97     &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
  98     "Minimum Retransmission Timeout");
  99
 100 int     tcp_rexmit_slop;
 101 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
 102     &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
 103     "Retransmission Timer Slop");
 104
 105 static int      always_keepalive = 1;
 106 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW,
 107     &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections");
 108
 109 int    tcp_fast_finwait2_recycle = 0;
 110 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
 111     &tcp_fast_finwait2_recycle, 0,
 112     "Recycle closed FIN_WAIT_2 connections faster");
 113
 114 int    tcp_finwait2_timeout;
 115 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW,
 116     &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout");
 117
 118 int     tcp_keepcnt = TCPTV_KEEPCNT;
 119 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
 120     "Number of keepalive probes to send");
 121
 122         /* max idle probes */
 123 int     tcp_maxpersistidle;
 124
 125 static int      tcp_rexmit_drop_options = 0;
 126 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
 127     &tcp_rexmit_drop_options, 0,
 128     "Drop TCP options from 3rd and later retransmitted SYN");
 129
 130 static int      per_cpu_timers = 0;
 131 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
 132     &per_cpu_timers , 0, "run tcp timers on all cpus");
 133
 134 #if 0
 135 #define INP_CPU(inp)    (per_cpu_timers ? (!CPU_ABSENT(((inp)->inp_flowid % (mp_maxid+1))) ? \
 136                 ((inp)->inp_flowid % (mp_maxid+1)) : curcpu) : 0)
 137 #endif
 138
 139 /*
 140  * Map the given inp to a CPU id.
 141  *
 142  * This queries RSS if it's compiled in, else it defaults to the current
 143  * CPU ID.
 144  */
 145 static inline int
 146 inp_to_cpuid(struct inpcb *inp)
 147 {
 148         u_int cpuid;
 149
 150 #ifdef  RSS
 151         if (per_cpu_timers) {
 152                 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
 153                 if (cpuid == NETISR_CPUID_NONE)
 154                         return (curcpu);        /* XXX */
 155                 else
 156                         return (cpuid);
 157         }
 158 #else
 159         /* Legacy, pre-RSS behaviour */
 160         if (per_cpu_timers) {
 161                 /*
 162                  * We don't have a flowid -> cpuid mapping, so cheat and
 163                  * just map unknown cpuids to curcpu.  Not the best, but
 164                  * apparently better than defaulting to swi 0.
 165                  */
 166                 cpuid = inp->inp_flowid % (mp_maxid + 1);
 167                 if (! CPU_ABSENT(cpuid))
 168                         return (cpuid);
 169                 return (curcpu);
 170         }
 171 #endif
 172         /* Default for RSS and non-RSS - cpuid 0 */
 173         else {
 174                 return (0);
 175         }
 176 }
 177
 178 /*
 179  * Tcp protocol timeout routine called every 500 ms.
 180  * Updates timestamps used for TCP
 181  * causes finite state machine actions if timers expire.
 182  */
 183 void
 184 tcp_slowtimo(void)
 185 {
 186         VNET_ITERATOR_DECL(vnet_iter);
 187
 188         VNET_LIST_RLOCK_NOSLEEP();
 189         VNET_FOREACH(vnet_iter) {
 190                 CURVNET_SET(vnet_iter);
 191                 tcp_tw_2msl_scan();
 192                 CURVNET_RESTORE();
 193         }
 194         VNET_LIST_RUNLOCK_NOSLEEP();
 195 }
 196
 197 int     tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] =
 198     { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 };
 199
 200 int     tcp_backoff[TCP_MAXRXTSHIFT + 1] =
 201     { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
 202
 203 static int tcp_totbackoff = 2559;       /* sum of tcp_backoff[] */
 204
 205 static int tcp_timer_race;
 206 SYSCTL_INT(_net_inet_tcp, OID_AUTO, timer_race, CTLFLAG_RD, &tcp_timer_race,
 207     0, "Count of t_inpcb races on tcp_discardcb");
 208
 209 /*
 210  * TCP timer processing.
 211  */
 212
 213 void
 214 tcp_timer_delack(void *xtp)
 215 {
 216         struct tcpcb *tp = xtp;
 217         struct inpcb *inp;
 218         CURVNET_SET(tp->t_vnet);
 219
 220         inp = tp->t_inpcb;
 221         /*
 222          * XXXRW: While this assert is in fact correct, bugs in the tcpcb
 223          * tear-down mean we need it as a work-around for races between
 224          * timers and tcp_discardcb().
 225          *
 226          * KASSERT(inp != NULL, ("tcp_timer_delack: inp == NULL"));
 227          */
 228         if (inp == NULL) {
 229                 tcp_timer_race++;
 230                 CURVNET_RESTORE();
 231                 return;
 232         }
 233         INP_WLOCK(inp);
 234         if (callout_pending(&tp->t_timers->tt_delack) ||
 235             !callout_active(&tp->t_timers->tt_delack)) {
 236                 INP_WUNLOCK(inp);
 237                 CURVNET_RESTORE();
 238                 return;
 239         }
 240         callout_deactivate(&tp->t_timers->tt_delack);
 241         if ((inp->inp_flags & INP_DROPPED) != 0) {
 242                 INP_WUNLOCK(inp);
 243                 CURVNET_RESTORE();
 244                 return;
 245         }
 246
 247         tp->t_flags |= TF_ACKNOW;
 248         TCPSTAT_INC(tcps_delack);
 249         (void) tcp_output(tp);
 250         INP_WUNLOCK(inp);
 251         CURVNET_RESTORE();
 252 }
 253
 254 void
 255 tcp_timer_2msl(void *xtp)
 256 {
 257         struct tcpcb *tp = xtp;
 258         struct inpcb *inp;
 259         CURVNET_SET(tp->t_vnet);
 260 #ifdef TCPDEBUG
 261         int ostate;
 262
 263         ostate = tp->t_state;
 264 #endif
 265         /*
 266          * XXXRW: Does this actually happen?
 267          */
 268         INP_INFO_WLOCK(&V_tcbinfo);
 269         inp = tp->t_inpcb;
 270         /*
 271          * XXXRW: While this assert is in fact correct, bugs in the tcpcb
 272          * tear-down mean we need it as a work-around for races between
 273          * timers and tcp_discardcb().
 274          *
 275          * KASSERT(inp != NULL, ("tcp_timer_2msl: inp == NULL"));
 276          */
 277         if (inp == NULL) {
 278                 tcp_timer_race++;
 279                 INP_INFO_WUNLOCK(&V_tcbinfo);
 280                 CURVNET_RESTORE();
 281                 return;
 282         }
 283         INP_WLOCK(inp);
 284         tcp_free_sackholes(tp);
 285         if (callout_pending(&tp->t_timers->tt_2msl) ||
 286             !callout_active(&tp->t_timers->tt_2msl)) {
 287                 INP_WUNLOCK(tp->t_inpcb);
 288                 INP_INFO_WUNLOCK(&V_tcbinfo);
 289                 CURVNET_RESTORE();
 290                 return;
 291         }
 292         callout_deactivate(&tp->t_timers->tt_2msl);
 293         if ((inp->inp_flags & INP_DROPPED) != 0) {
 294                 INP_WUNLOCK(inp);
 295                 INP_INFO_WUNLOCK(&V_tcbinfo);
 296                 CURVNET_RESTORE();
 297                 return;
 298         }
 299         /*
 300          * 2 MSL timeout in shutdown went off.  If we're closed but
 301          * still waiting for peer to close and connection has been idle
 302          * too long, or if 2MSL time is up from TIME_WAIT, delete connection
 303          * control block.  Otherwise, check again in a bit.
 304          *
 305          * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
 306          * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
 307          * Ignore fact that there were recent incoming segments.
 308          */
 309         if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
 310             tp->t_inpcb && tp->t_inpcb->inp_socket &&
 311             (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
 312                 TCPSTAT_INC(tcps_finwait2_drops);
 313                 tp = tcp_close(tp);
 314         } else {
 315                 if (tp->t_state != TCPS_TIME_WAIT &&
 316                    ticks - tp->t_rcvtime <= TP_MAXIDLE(tp))
 317                        callout_reset_on(&tp->t_timers->tt_2msl,
 318                            TP_KEEPINTVL(tp), tcp_timer_2msl, tp,
 319                            inp_to_cpuid(inp));
 320                else
 321                        tp = tcp_close(tp);
 322        }
 323
 324 #ifdef TCPDEBUG
 325         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 326                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 327                           PRU_SLOWTIMO);
 328 #endif
 329         if (tp != NULL)
 330                 INP_WUNLOCK(inp);
 331         INP_INFO_WUNLOCK(&V_tcbinfo);
 332         CURVNET_RESTORE();
 333 }
 334
 335 void
 336 tcp_timer_keep(void *xtp)
 337 {
 338         struct tcpcb *tp = xtp;
 339         struct tcptemp *t_template;
 340         struct inpcb *inp;
 341         CURVNET_SET(tp->t_vnet);
 342 #ifdef TCPDEBUG
 343         int ostate;
 344
 345         ostate = tp->t_state;
 346 #endif
 347         INP_INFO_WLOCK(&V_tcbinfo);
 348         inp = tp->t_inpcb;
 349         /*
 350          * XXXRW: While this assert is in fact correct, bugs in the tcpcb
 351          * tear-down mean we need it as a work-around for races between
 352          * timers and tcp_discardcb().
 353          *
 354          * KASSERT(inp != NULL, ("tcp_timer_keep: inp == NULL"));
 355          */
 356         if (inp == NULL) {
 357                 tcp_timer_race++;
 358                 INP_INFO_WUNLOCK(&V_tcbinfo);
 359                 CURVNET_RESTORE();
 360                 return;
 361         }
 362         INP_WLOCK(inp);
 363         if (callout_pending(&tp->t_timers->tt_keep) ||
 364             !callout_active(&tp->t_timers->tt_keep)) {
 365                 INP_WUNLOCK(inp);
 366                 INP_INFO_WUNLOCK(&V_tcbinfo);
 367                 CURVNET_RESTORE();
 368                 return;
 369         }
 370         callout_deactivate(&tp->t_timers->tt_keep);
 371         if ((inp->inp_flags & INP_DROPPED) != 0) {
 372                 INP_WUNLOCK(inp);
 373                 INP_INFO_WUNLOCK(&V_tcbinfo);
 374                 CURVNET_RESTORE();
 375                 return;
 376         }
 377         /*
 378          * Keep-alive timer went off; send something
 379          * or drop connection if idle for too long.
 380          */
 381         TCPSTAT_INC(tcps_keeptimeo);
 382         if (tp->t_state < TCPS_ESTABLISHED)
 383                 goto dropit;
 384         if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) &&
 385             tp->t_state <= TCPS_CLOSING) {
 386                 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
 387                         goto dropit;
 388                 /*
 389                  * Send a packet designed to force a response
 390                  * if the peer is up and reachable:
 391                  * either an ACK if the connection is still alive,
 392                  * or an RST if the peer has closed the connection
 393                  * due to timeout or reboot.
 394                  * Using sequence number tp->snd_una-1
 395                  * causes the transmitted zero-length segment
 396                  * to lie outside the receive window;
 397                  * by the protocol spec, this requires the
 398                  * correspondent TCP to respond.
 399                  */
 400                 TCPSTAT_INC(tcps_keepprobe);
 401                 t_template = tcpip_maketemplate(inp);
 402                 if (t_template) {
 403                         tcp_respond(tp, t_template->tt_ipgen,
 404                                     &t_template->tt_t, (struct mbuf *)NULL,
 405                                     tp->rcv_nxt, tp->snd_una - 1, 0);
 406                         free(t_template, M_TEMP);
 407                 }
 408                 callout_reset_on(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
 409                     tcp_timer_keep, tp, inp_to_cpuid(inp));
 410         } else
 411                 callout_reset_on(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
 412                     tcp_timer_keep, tp, inp_to_cpuid(inp));
 413
 414 #ifdef TCPDEBUG
 415         if (inp->inp_socket->so_options & SO_DEBUG)
 416                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 417                           PRU_SLOWTIMO);
 418 #endif
 419         INP_WUNLOCK(inp);
 420         INP_INFO_WUNLOCK(&V_tcbinfo);
 421         CURVNET_RESTORE();
 422         return;
 423
 424 dropit:
 425         TCPSTAT_INC(tcps_keepdrops);
 426         tp = tcp_drop(tp, ETIMEDOUT);
 427
 428 #ifdef TCPDEBUG
 429         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 430                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 431                           PRU_SLOWTIMO);
 432 #endif
 433         if (tp != NULL)
 434                 INP_WUNLOCK(tp->t_inpcb);
 435         INP_INFO_WUNLOCK(&V_tcbinfo);
 436         CURVNET_RESTORE();
 437 }
 438
 439 void
 440 tcp_timer_persist(void *xtp)
 441 {
 442         struct tcpcb *tp = xtp;
 443         struct inpcb *inp;
 444         CURVNET_SET(tp->t_vnet);
 445 #ifdef TCPDEBUG
 446         int ostate;
 447
 448         ostate = tp->t_state;
 449 #endif
 450         INP_INFO_WLOCK(&V_tcbinfo);
 451         inp = tp->t_inpcb;
 452         /*
 453          * XXXRW: While this assert is in fact correct, bugs in the tcpcb
 454          * tear-down mean we need it as a work-around for races between
 455          * timers and tcp_discardcb().
 456          *
 457          * KASSERT(inp != NULL, ("tcp_timer_persist: inp == NULL"));
 458          */
 459         if (inp == NULL) {
 460                 tcp_timer_race++;
 461                 INP_INFO_WUNLOCK(&V_tcbinfo);
 462                 CURVNET_RESTORE();
 463                 return;
 464         }
 465         INP_WLOCK(inp);
 466         if (callout_pending(&tp->t_timers->tt_persist) ||
 467             !callout_active(&tp->t_timers->tt_persist)) {
 468                 INP_WUNLOCK(inp);
 469                 INP_INFO_WUNLOCK(&V_tcbinfo);
 470                 CURVNET_RESTORE();
 471                 return;
 472         }
 473         callout_deactivate(&tp->t_timers->tt_persist);
 474         if ((inp->inp_flags & INP_DROPPED) != 0) {
 475                 INP_WUNLOCK(inp);
 476                 INP_INFO_WUNLOCK(&V_tcbinfo);
 477                 CURVNET_RESTORE();
 478                 return;
 479         }
 480         /*
 481          * Persistance timer into zero window.
 482          * Force a byte to be output, if possible.
 483          */
 484         TCPSTAT_INC(tcps_persisttimeo);
 485         /*
 486          * Hack: if the peer is dead/unreachable, we do not
 487          * time out if the window is closed.  After a full
 488          * backoff, drop the connection if the idle time
 489          * (no responses to probes) reaches the maximum
 490          * backoff that we would use if retransmitting.
 491          */
 492         if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
 493             (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
 494              ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
 495                 TCPSTAT_INC(tcps_persistdrop);
 496                 tp = tcp_drop(tp, ETIMEDOUT);
 497                 goto out;
 498         }
 499         /*
 500          * If the user has closed the socket then drop a persisting
 501          * connection after a much reduced timeout.
 502          */
 503         if (tp->t_state > TCPS_CLOSE_WAIT &&
 504             (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
 505                 TCPSTAT_INC(tcps_persistdrop);
 506                 tp = tcp_drop(tp, ETIMEDOUT);
 507                 goto out;
 508         }
 509         tcp_setpersist(tp);
 510         tp->t_flags |= TF_FORCEDATA;
 511         (void) tcp_output(tp);
 512         tp->t_flags &= ~TF_FORCEDATA;
 513
 514 out:
 515 #ifdef TCPDEBUG
 516         if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
 517                 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
 518 #endif
 519         if (tp != NULL)
 520                 INP_WUNLOCK(inp);
 521         INP_INFO_WUNLOCK(&V_tcbinfo);
 522         CURVNET_RESTORE();
 523 }
 524
 525 void
 526 tcp_timer_rexmt(void * xtp)
 527 {
 528         struct tcpcb *tp = xtp;
 529         CURVNET_SET(tp->t_vnet);
 530         int rexmt;
 531         int headlocked;
 532         struct inpcb *inp;
 533 #ifdef TCPDEBUG
 534         int ostate;
 535
 536         ostate = tp->t_state;
 537 #endif
 538         INP_INFO_RLOCK(&V_tcbinfo);
 539         inp = tp->t_inpcb;
 540         /*
 541          * XXXRW: While this assert is in fact correct, bugs in the tcpcb
 542          * tear-down mean we need it as a work-around for races between
 543          * timers and tcp_discardcb().
 544          *
 545          * KASSERT(inp != NULL, ("tcp_timer_rexmt: inp == NULL"));
 546          */
 547         if (inp == NULL) {
 548                 tcp_timer_race++;
 549                 INP_INFO_RUNLOCK(&V_tcbinfo);
 550                 CURVNET_RESTORE();
 551                 return;
 552         }
 553         INP_WLOCK(inp);
 554         if (callout_pending(&tp->t_timers->tt_rexmt) ||
 555             !callout_active(&tp->t_timers->tt_rexmt)) {
 556                 INP_WUNLOCK(inp);
 557                 INP_INFO_RUNLOCK(&V_tcbinfo);
 558                 CURVNET_RESTORE();
 559                 return;
 560         }
 561         callout_deactivate(&tp->t_timers->tt_rexmt);
 562         if ((inp->inp_flags & INP_DROPPED) != 0) {
 563                 INP_WUNLOCK(inp);
 564                 INP_INFO_RUNLOCK(&V_tcbinfo);
 565                 CURVNET_RESTORE();
 566                 return;
 567         }
 568         tcp_free_sackholes(tp);
 569         /*
 570          * Retransmission timer went off.  Message has not
 571          * been acked within retransmit interval.  Back off
 572          * to a longer retransmit interval and retransmit one segment.
 573          */
 574         if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
 575                 tp->t_rxtshift = TCP_MAXRXTSHIFT;
 576                 TCPSTAT_INC(tcps_timeoutdrop);
 577                 in_pcbref(inp);
 578                 INP_INFO_RUNLOCK(&V_tcbinfo);
 579                 INP_WUNLOCK(inp);
 580                 INP_INFO_WLOCK(&V_tcbinfo);
 581                 INP_WLOCK(inp);
 582                 if (in_pcbrele_wlocked(inp)) {
 583                         INP_INFO_WUNLOCK(&V_tcbinfo);
 584                         CURVNET_RESTORE();
 585                         return;
 586                 }
 587                 if (inp->inp_flags & INP_DROPPED) {
 588                         INP_WUNLOCK(inp);
 589                         INP_INFO_WUNLOCK(&V_tcbinfo);
 590                         CURVNET_RESTORE();
 591                         return;
 592                 }
 593
 594                 tp = tcp_drop(tp, tp->t_softerror ?
 595                               tp->t_softerror : ETIMEDOUT);
 596                 headlocked = 1;
 597                 goto out;
 598         }
 599         INP_INFO_RUNLOCK(&V_tcbinfo);
 600         headlocked = 0;
 601         if (tp->t_state == TCPS_SYN_SENT) {
 602                 /*
 603                  * If the SYN was retransmitted, indicate CWND to be
 604                  * limited to 1 segment in cc_conn_init().
 605                  */
 606                 tp->snd_cwnd = 1;
 607         } else if (tp->t_rxtshift == 1) {
 608                 /*
 609                  * first retransmit; record ssthresh and cwnd so they can
 610                  * be recovered if this turns out to be a "bad" retransmit.
 611                  * A retransmit is considered "bad" if an ACK for this
 612                  * segment is received within RTT/2 interval; the assumption
 613                  * here is that the ACK was already in flight.  See
 614                  * "On Estimating End-to-End Network Path Properties" by
 615                  * Allman and Paxson for more details.
 616                  */
 617                 tp->snd_cwnd_prev = tp->snd_cwnd;
 618                 tp->snd_ssthresh_prev = tp->snd_ssthresh;
 619                 tp->snd_recover_prev = tp->snd_recover;
 620                 if (IN_FASTRECOVERY(tp->t_flags))
 621                         tp->t_flags |= TF_WASFRECOVERY;
 622                 else
 623                         tp->t_flags &= ~TF_WASFRECOVERY;
 624                 if (IN_CONGRECOVERY(tp->t_flags))
 625                         tp->t_flags |= TF_WASCRECOVERY;
 626                 else
 627                         tp->t_flags &= ~TF_WASCRECOVERY;
 628                 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
 629                 tp->t_flags |= TF_PREVVALID;
 630         } else
 631                 tp->t_flags &= ~TF_PREVVALID;
 632         TCPSTAT_INC(tcps_rexmttimeo);
 633         if (tp->t_state == TCPS_SYN_SENT)
 634                 rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift];
 635         else
 636                 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
 637         TCPT_RANGESET(tp->t_rxtcur, rexmt,
 638                       tp->t_rttmin, TCPTV_REXMTMAX);
 639         /*
 640          * Disable RFC1323 and SACK if we haven't got any response to
 641          * our third SYN to work-around some broken terminal servers
 642          * (most of which have hopefully been retired) that have bad VJ
 643          * header compression code which trashes TCP segments containing
 644          * unknown-to-them TCP options.
 645          */
 646         if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
 647             (tp->t_rxtshift == 3))
 648                 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
 649         /*
 650          * If we backed off this far, our srtt estimate is probably bogus.
 651          * Clobber it so we'll take the next rtt measurement as our srtt;
 652          * move the current srtt into rttvar to keep the current
 653          * retransmit times until then.
 654          */
 655         if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
 656 #ifdef INET6
 657                 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
 658                         in6_losing(tp->t_inpcb);
 659 #endif
 660                 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
 661                 tp->t_srtt = 0;
 662         }
 663         tp->snd_nxt = tp->snd_una;
 664         tp->snd_recover = tp->snd_max;
 665         /*
 666          * Force a segment to be sent.
 667          */
 668         tp->t_flags |= TF_ACKNOW;
 669         /*
 670          * If timing a segment in this window, stop the timer.
 671          */
 672         tp->t_rtttime = 0;
 673
 674         cc_cong_signal(tp, NULL, CC_RTO);
 675
 676         (void) tcp_output(tp);
 677
 678 out:
 679 #ifdef TCPDEBUG
 680         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 681                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 682                           PRU_SLOWTIMO);
 683 #endif
 684         if (tp != NULL)
 685                 INP_WUNLOCK(inp);
 686         if (headlocked)
 687                 INP_INFO_WUNLOCK(&V_tcbinfo);
 688         CURVNET_RESTORE();
 689 }
 690
 691 void
 692 tcp_timer_activate(struct tcpcb *tp, int timer_type, u_int delta)
 693 {
 694         struct callout *t_callout;
 695         void *f_callout;
 696         struct inpcb *inp = tp->t_inpcb;
 697         int cpu = inp_to_cpuid(inp);
 698
 699 #ifdef TCP_OFFLOAD
 700         if (tp->t_flags & TF_TOE)
 701                 return;
 702 #endif
 703
 704         switch (timer_type) {
 705                 case TT_DELACK:
 706                         t_callout = &tp->t_timers->tt_delack;
 707                         f_callout = tcp_timer_delack;
 708                         break;
 709                 case TT_REXMT:
 710                         t_callout = &tp->t_timers->tt_rexmt;
 711                         f_callout = tcp_timer_rexmt;
 712                         break;
 713                 case TT_PERSIST:
 714                         t_callout = &tp->t_timers->tt_persist;
 715                         f_callout = tcp_timer_persist;
 716                         break;
 717                 case TT_KEEP:
 718                         t_callout = &tp->t_timers->tt_keep;
 719                         f_callout = tcp_timer_keep;
 720                         break;
 721                 case TT_2MSL:
 722                         t_callout = &tp->t_timers->tt_2msl;
 723                         f_callout = tcp_timer_2msl;
 724                         break;
 725                 default:
 726                         panic("bad timer_type");
 727                 }
 728         if (delta == 0) {
 729                 callout_stop(t_callout);
 730         } else {
 731                 callout_reset_on(t_callout, delta, f_callout, tp, cpu);
 732         }
 733 }
 734
 735 int
 736 tcp_timer_active(struct tcpcb *tp, int timer_type)
 737 {
 738         struct callout *t_callout;
 739
 740         switch (timer_type) {
 741                 case TT_DELACK:
 742                         t_callout = &tp->t_timers->tt_delack;
 743                         break;
 744                 case TT_REXMT:
 745                         t_callout = &tp->t_timers->tt_rexmt;
 746                         break;
 747                 case TT_PERSIST:
 748                         t_callout = &tp->t_timers->tt_persist;
 749                         break;
 750                 case TT_KEEP:
 751                         t_callout = &tp->t_timers->tt_keep;
 752                         break;
 753                 case TT_2MSL:
 754                         t_callout = &tp->t_timers->tt_2msl;
 755                         break;
 756                 default:
 757                         panic("bad timer_type");
 758                 }
 759         return callout_active(t_callout);
 760 }
 761
 762 #define ticks_to_msecs(t)       (1000*(t) / hz)
 763
 764 void
 765 tcp_timer_to_xtimer(struct tcpcb *tp, struct tcp_timer *timer,
 766     struct xtcp_timer *xtimer)
 767 {
 768         sbintime_t now;
 769
 770         bzero(xtimer, sizeof(*xtimer));
 771         if (timer == NULL)
 772                 return;
 773         now = getsbinuptime();
 774         if (callout_active(&timer->tt_delack))
 775                 xtimer->tt_delack = (timer->tt_delack.c_time - now) / SBT_1MS;
 776         if (callout_active(&timer->tt_rexmt))
 777                 xtimer->tt_rexmt = (timer->tt_rexmt.c_time - now) / SBT_1MS;
 778         if (callout_active(&timer->tt_persist))
 779                 xtimer->tt_persist = (timer->tt_persist.c_time - now) / SBT_1MS;
 780         if (callout_active(&timer->tt_keep))
 781                 xtimer->tt_keep = (timer->tt_keep.c_time - now) / SBT_1MS;
 782         if (callout_active(&timer->tt_2msl))
 783                 xtimer->tt_2msl = (timer->tt_2msl.c_time - now) / SBT_1MS;
 784         xtimer->t_rcvtime = ticks_to_msecs(ticks - tp->t_rcvtime);
 785 }