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/rss_config.h>
  55 #include <net/vnet.h>
  56 #include <net/netisr.h>
  57
  58 #include <netinet/cc.h>
  59 #include <netinet/in.h>
  60 #include <netinet/in_pcb.h>
  61 #include <netinet/in_rss.h>
  62 #include <netinet/in_systm.h>
  63 #ifdef INET6
  64 #include <netinet6/in6_pcb.h>
  65 #endif
  66 #include <netinet/ip_var.h>
  67 #include <netinet/tcp_fsm.h>
  68 #include <netinet/tcp_timer.h>
  69 #include <netinet/tcp_var.h>
  70 #ifdef INET6
  71 #include <netinet6/tcp6_var.h>
  72 #endif
  73 #include <netinet/tcpip.h>
  74 #ifdef TCPDEBUG
  75 #include <netinet/tcp_debug.h>
  76 #endif
  77
  78 int     tcp_keepinit;
  79 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
  80     &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "time to establish connection");
  81
  82 int     tcp_keepidle;
  83 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
  84     &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "time before keepalive probes begin");
  85
  86 int     tcp_keepintvl;
  87 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
  88     &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "time between keepalive probes");
  89
  90 int     tcp_delacktime;
  91 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW,
  92     &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
  93     "Time before a delayed ACK is sent");
  94
  95 int     tcp_msl;
  96 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
  97     &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
  98
  99 int     tcp_rexmit_min;
 100 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
 101     &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
 102     "Minimum Retransmission Timeout");
 103
 104 int     tcp_rexmit_slop;
 105 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
 106     &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
 107     "Retransmission Timer Slop");
 108
 109 static int      always_keepalive = 1;
 110 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW,
 111     &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections");
 112
 113 int    tcp_fast_finwait2_recycle = 0;
 114 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
 115     &tcp_fast_finwait2_recycle, 0,
 116     "Recycle closed FIN_WAIT_2 connections faster");
 117
 118 int    tcp_finwait2_timeout;
 119 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW,
 120     &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout");
 121
 122 int     tcp_keepcnt = TCPTV_KEEPCNT;
 123 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
 124     "Number of keepalive probes to send");
 125
 126         /* max idle probes */
 127 int     tcp_maxpersistidle;
 128
 129 static int      tcp_rexmit_drop_options = 0;
 130 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
 131     &tcp_rexmit_drop_options, 0,
 132     "Drop TCP options from 3rd and later retransmitted SYN");
 133
 134 static VNET_DEFINE(int, tcp_pmtud_blackhole_detect);
 135 #define V_tcp_pmtud_blackhole_detect    VNET(tcp_pmtud_blackhole_detect)
 136 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection,
 137     CTLFLAG_RW|CTLFLAG_VNET,
 138     &VNET_NAME(tcp_pmtud_blackhole_detect), 0,
 139     "Path MTU Discovery Black Hole Detection Enabled");
 140
 141 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated);
 142 #define V_tcp_pmtud_blackhole_activated \
 143     VNET(tcp_pmtud_blackhole_activated)
 144 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated,
 145     CTLFLAG_RD|CTLFLAG_VNET,
 146     &VNET_NAME(tcp_pmtud_blackhole_activated), 0,
 147     "Path MTU Discovery Black Hole Detection, Activation Count");
 148
 149 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated_min_mss);
 150 #define V_tcp_pmtud_blackhole_activated_min_mss \
 151     VNET(tcp_pmtud_blackhole_activated_min_mss)
 152 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated_min_mss,
 153     CTLFLAG_RD|CTLFLAG_VNET,
 154     &VNET_NAME(tcp_pmtud_blackhole_activated_min_mss), 0,
 155     "Path MTU Discovery Black Hole Detection, Activation Count at min MSS");
 156
 157 static VNET_DEFINE(int, tcp_pmtud_blackhole_failed);
 158 #define V_tcp_pmtud_blackhole_failed    VNET(tcp_pmtud_blackhole_failed)
 159 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_failed,
 160     CTLFLAG_RD|CTLFLAG_VNET,
 161     &VNET_NAME(tcp_pmtud_blackhole_failed), 0,
 162     "Path MTU Discovery Black Hole Detection, Failure Count");
 163
 164 #ifdef INET
 165 static VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200;
 166 #define V_tcp_pmtud_blackhole_mss       VNET(tcp_pmtud_blackhole_mss)
 167 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss,
 168     CTLFLAG_RW|CTLFLAG_VNET,
 169     &VNET_NAME(tcp_pmtud_blackhole_mss), 0,
 170     "Path MTU Discovery Black Hole Detection lowered MSS");
 171 #endif
 172
 173 #ifdef INET6
 174 static VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220;
 175 #define V_tcp_v6pmtud_blackhole_mss     VNET(tcp_v6pmtud_blackhole_mss)
 176 SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss,
 177     CTLFLAG_RW|CTLFLAG_VNET,
 178     &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0,
 179     "Path MTU Discovery IPv6 Black Hole Detection lowered MSS");
 180 #endif
 181
 182 #ifdef  RSS
 183 static int      per_cpu_timers = 1;
 184 #else
 185 static int      per_cpu_timers = 0;
 186 #endif
 187 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
 188     &per_cpu_timers , 0, "run tcp timers on all cpus");
 189
 190 #if 0
 191 #define INP_CPU(inp)    (per_cpu_timers ? (!CPU_ABSENT(((inp)->inp_flowid % (mp_maxid+1))) ? \
 192                 ((inp)->inp_flowid % (mp_maxid+1)) : curcpu) : 0)
 193 #endif
 194
 195 /*
 196  * Map the given inp to a CPU id.
 197  *
 198  * This queries RSS if it's compiled in, else it defaults to the current
 199  * CPU ID.
 200  */
 201 static inline int
 202 inp_to_cpuid(struct inpcb *inp)
 203 {
 204         u_int cpuid;
 205
 206 #ifdef  RSS
 207         if (per_cpu_timers) {
 208                 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
 209                 if (cpuid == NETISR_CPUID_NONE)
 210                         return (curcpu);        /* XXX */
 211                 else
 212                         return (cpuid);
 213         }
 214 #else
 215         /* Legacy, pre-RSS behaviour */
 216         if (per_cpu_timers) {
 217                 /*
 218                  * We don't have a flowid -> cpuid mapping, so cheat and
 219                  * just map unknown cpuids to curcpu.  Not the best, but
 220                  * apparently better than defaulting to swi 0.
 221                  */
 222                 cpuid = inp->inp_flowid % (mp_maxid + 1);
 223                 if (! CPU_ABSENT(cpuid))
 224                         return (cpuid);
 225                 return (curcpu);
 226         }
 227 #endif
 228         /* Default for RSS and non-RSS - cpuid 0 */
 229         else {
 230                 return (0);
 231         }
 232 }
 233
 234 /*
 235  * Tcp protocol timeout routine called every 500 ms.
 236  * Updates timestamps used for TCP
 237  * causes finite state machine actions if timers expire.
 238  */
 239 void
 240 tcp_slowtimo(void)
 241 {
 242         VNET_ITERATOR_DECL(vnet_iter);
 243
 244         VNET_LIST_RLOCK_NOSLEEP();
 245         VNET_FOREACH(vnet_iter) {
 246                 CURVNET_SET(vnet_iter);
 247                 (void) tcp_tw_2msl_scan(0);
 248                 CURVNET_RESTORE();
 249         }
 250         VNET_LIST_RUNLOCK_NOSLEEP();
 251 }
 252
 253 int     tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] =
 254     { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 };
 255
 256 int     tcp_backoff[TCP_MAXRXTSHIFT + 1] =
 257     { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
 258
 259 static int tcp_totbackoff = 2559;       /* sum of tcp_backoff[] */
 260
 261 static int tcp_timer_race;
 262 SYSCTL_INT(_net_inet_tcp, OID_AUTO, timer_race, CTLFLAG_RD, &tcp_timer_race,
 263     0, "Count of t_inpcb races on tcp_discardcb");
 264
 265 /*
 266  * TCP timer processing.
 267  */
 268
 269 void
 270 tcp_timer_delack(void *xtp)
 271 {
 272         struct tcpcb *tp = xtp;
 273         struct inpcb *inp;
 274         CURVNET_SET(tp->t_vnet);
 275
 276         inp = tp->t_inpcb;
 277         /*
 278          * XXXRW: While this assert is in fact correct, bugs in the tcpcb
 279          * tear-down mean we need it as a work-around for races between
 280          * timers and tcp_discardcb().
 281          *
 282          * KASSERT(inp != NULL, ("tcp_timer_delack: inp == NULL"));
 283          */
 284         if (inp == NULL) {
 285                 tcp_timer_race++;
 286                 CURVNET_RESTORE();
 287                 return;
 288         }
 289         INP_WLOCK(inp);
 290         if (callout_pending(&tp->t_timers->tt_delack) ||
 291             !callout_active(&tp->t_timers->tt_delack)) {
 292                 INP_WUNLOCK(inp);
 293                 CURVNET_RESTORE();
 294                 return;
 295         }
 296         callout_deactivate(&tp->t_timers->tt_delack);
 297         if ((inp->inp_flags & INP_DROPPED) != 0) {
 298                 INP_WUNLOCK(inp);
 299                 CURVNET_RESTORE();
 300                 return;
 301         }
 302
 303         tp->t_flags |= TF_ACKNOW;
 304         TCPSTAT_INC(tcps_delack);
 305         (void) tcp_output(tp);
 306         INP_WUNLOCK(inp);
 307         CURVNET_RESTORE();
 308 }
 309
 310 void
 311 tcp_timer_2msl(void *xtp)
 312 {
 313         struct tcpcb *tp = xtp;
 314         struct inpcb *inp;
 315         CURVNET_SET(tp->t_vnet);
 316 #ifdef TCPDEBUG
 317         int ostate;
 318
 319         ostate = tp->t_state;
 320 #endif
 321         /*
 322          * XXXRW: Does this actually happen?
 323          */
 324         INP_INFO_WLOCK(&V_tcbinfo);
 325         inp = tp->t_inpcb;
 326         /*
 327          * XXXRW: While this assert is in fact correct, bugs in the tcpcb
 328          * tear-down mean we need it as a work-around for races between
 329          * timers and tcp_discardcb().
 330          *
 331          * KASSERT(inp != NULL, ("tcp_timer_2msl: inp == NULL"));
 332          */
 333         if (inp == NULL) {
 334                 tcp_timer_race++;
 335                 INP_INFO_WUNLOCK(&V_tcbinfo);
 336                 CURVNET_RESTORE();
 337                 return;
 338         }
 339         INP_WLOCK(inp);
 340         tcp_free_sackholes(tp);
 341         if (callout_pending(&tp->t_timers->tt_2msl) ||
 342             !callout_active(&tp->t_timers->tt_2msl)) {
 343                 INP_WUNLOCK(tp->t_inpcb);
 344                 INP_INFO_WUNLOCK(&V_tcbinfo);
 345                 CURVNET_RESTORE();
 346                 return;
 347         }
 348         callout_deactivate(&tp->t_timers->tt_2msl);
 349         if ((inp->inp_flags & INP_DROPPED) != 0) {
 350                 INP_WUNLOCK(inp);
 351                 INP_INFO_WUNLOCK(&V_tcbinfo);
 352                 CURVNET_RESTORE();
 353                 return;
 354         }
 355         /*
 356          * 2 MSL timeout in shutdown went off.  If we're closed but
 357          * still waiting for peer to close and connection has been idle
 358          * too long, or if 2MSL time is up from TIME_WAIT, delete connection
 359          * control block.  Otherwise, check again in a bit.
 360          *
 361          * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
 362          * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
 363          * Ignore fact that there were recent incoming segments.
 364          */
 365         if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
 366             tp->t_inpcb && tp->t_inpcb->inp_socket &&
 367             (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
 368                 TCPSTAT_INC(tcps_finwait2_drops);
 369                 tp = tcp_close(tp);
 370         } else {
 371                 if (tp->t_state != TCPS_TIME_WAIT &&
 372                    ticks - tp->t_rcvtime <= TP_MAXIDLE(tp))
 373                        callout_reset_on(&tp->t_timers->tt_2msl,
 374                            TP_KEEPINTVL(tp), tcp_timer_2msl, tp,
 375                            inp_to_cpuid(inp));
 376                else
 377                        tp = tcp_close(tp);
 378        }
 379
 380 #ifdef TCPDEBUG
 381         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 382                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 383                           PRU_SLOWTIMO);
 384 #endif
 385         if (tp != NULL)
 386                 INP_WUNLOCK(inp);
 387         INP_INFO_WUNLOCK(&V_tcbinfo);
 388         CURVNET_RESTORE();
 389 }
 390
 391 void
 392 tcp_timer_keep(void *xtp)
 393 {
 394         struct tcpcb *tp = xtp;
 395         struct tcptemp *t_template;
 396         struct inpcb *inp;
 397         CURVNET_SET(tp->t_vnet);
 398 #ifdef TCPDEBUG
 399         int ostate;
 400
 401         ostate = tp->t_state;
 402 #endif
 403         INP_INFO_WLOCK(&V_tcbinfo);
 404         inp = tp->t_inpcb;
 405         /*
 406          * XXXRW: While this assert is in fact correct, bugs in the tcpcb
 407          * tear-down mean we need it as a work-around for races between
 408          * timers and tcp_discardcb().
 409          *
 410          * KASSERT(inp != NULL, ("tcp_timer_keep: inp == NULL"));
 411          */
 412         if (inp == NULL) {
 413                 tcp_timer_race++;
 414                 INP_INFO_WUNLOCK(&V_tcbinfo);
 415                 CURVNET_RESTORE();
 416                 return;
 417         }
 418         INP_WLOCK(inp);
 419         if (callout_pending(&tp->t_timers->tt_keep) ||
 420             !callout_active(&tp->t_timers->tt_keep)) {
 421                 INP_WUNLOCK(inp);
 422                 INP_INFO_WUNLOCK(&V_tcbinfo);
 423                 CURVNET_RESTORE();
 424                 return;
 425         }
 426         callout_deactivate(&tp->t_timers->tt_keep);
 427         if ((inp->inp_flags & INP_DROPPED) != 0) {
 428                 INP_WUNLOCK(inp);
 429                 INP_INFO_WUNLOCK(&V_tcbinfo);
 430                 CURVNET_RESTORE();
 431                 return;
 432         }
 433         /*
 434          * Keep-alive timer went off; send something
 435          * or drop connection if idle for too long.
 436          */
 437         TCPSTAT_INC(tcps_keeptimeo);
 438         if (tp->t_state < TCPS_ESTABLISHED)
 439                 goto dropit;
 440         if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) &&
 441             tp->t_state <= TCPS_CLOSING) {
 442                 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
 443                         goto dropit;
 444                 /*
 445                  * Send a packet designed to force a response
 446                  * if the peer is up and reachable:
 447                  * either an ACK if the connection is still alive,
 448                  * or an RST if the peer has closed the connection
 449                  * due to timeout or reboot.
 450                  * Using sequence number tp->snd_una-1
 451                  * causes the transmitted zero-length segment
 452                  * to lie outside the receive window;
 453                  * by the protocol spec, this requires the
 454                  * correspondent TCP to respond.
 455                  */
 456                 TCPSTAT_INC(tcps_keepprobe);
 457                 t_template = tcpip_maketemplate(inp);
 458                 if (t_template) {
 459                         tcp_respond(tp, t_template->tt_ipgen,
 460                                     &t_template->tt_t, (struct mbuf *)NULL,
 461                                     tp->rcv_nxt, tp->snd_una - 1, 0);
 462                         free(t_template, M_TEMP);
 463                 }
 464                 callout_reset_on(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
 465                     tcp_timer_keep, tp, inp_to_cpuid(inp));
 466         } else
 467                 callout_reset_on(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
 468                     tcp_timer_keep, tp, inp_to_cpuid(inp));
 469
 470 #ifdef TCPDEBUG
 471         if (inp->inp_socket->so_options & SO_DEBUG)
 472                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 473                           PRU_SLOWTIMO);
 474 #endif
 475         INP_WUNLOCK(inp);
 476         INP_INFO_WUNLOCK(&V_tcbinfo);
 477         CURVNET_RESTORE();
 478         return;
 479
 480 dropit:
 481         TCPSTAT_INC(tcps_keepdrops);
 482         tp = tcp_drop(tp, ETIMEDOUT);
 483
 484 #ifdef TCPDEBUG
 485         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 486                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 487                           PRU_SLOWTIMO);
 488 #endif
 489         if (tp != NULL)
 490                 INP_WUNLOCK(tp->t_inpcb);
 491         INP_INFO_WUNLOCK(&V_tcbinfo);
 492         CURVNET_RESTORE();
 493 }
 494
 495 void
 496 tcp_timer_persist(void *xtp)
 497 {
 498         struct tcpcb *tp = xtp;
 499         struct inpcb *inp;
 500         CURVNET_SET(tp->t_vnet);
 501 #ifdef TCPDEBUG
 502         int ostate;
 503
 504         ostate = tp->t_state;
 505 #endif
 506         INP_INFO_WLOCK(&V_tcbinfo);
 507         inp = tp->t_inpcb;
 508         /*
 509          * XXXRW: While this assert is in fact correct, bugs in the tcpcb
 510          * tear-down mean we need it as a work-around for races between
 511          * timers and tcp_discardcb().
 512          *
 513          * KASSERT(inp != NULL, ("tcp_timer_persist: inp == NULL"));
 514          */
 515         if (inp == NULL) {
 516                 tcp_timer_race++;
 517                 INP_INFO_WUNLOCK(&V_tcbinfo);
 518                 CURVNET_RESTORE();
 519                 return;
 520         }
 521         INP_WLOCK(inp);
 522         if (callout_pending(&tp->t_timers->tt_persist) ||
 523             !callout_active(&tp->t_timers->tt_persist)) {
 524                 INP_WUNLOCK(inp);
 525                 INP_INFO_WUNLOCK(&V_tcbinfo);
 526                 CURVNET_RESTORE();
 527                 return;
 528         }
 529         callout_deactivate(&tp->t_timers->tt_persist);
 530         if ((inp->inp_flags & INP_DROPPED) != 0) {
 531                 INP_WUNLOCK(inp);
 532                 INP_INFO_WUNLOCK(&V_tcbinfo);
 533                 CURVNET_RESTORE();
 534                 return;
 535         }
 536         /*
 537          * Persistance timer into zero window.
 538          * Force a byte to be output, if possible.
 539          */
 540         TCPSTAT_INC(tcps_persisttimeo);
 541         /*
 542          * Hack: if the peer is dead/unreachable, we do not
 543          * time out if the window is closed.  After a full
 544          * backoff, drop the connection if the idle time
 545          * (no responses to probes) reaches the maximum
 546          * backoff that we would use if retransmitting.
 547          */
 548         if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
 549             (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
 550              ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
 551                 TCPSTAT_INC(tcps_persistdrop);
 552                 tp = tcp_drop(tp, ETIMEDOUT);
 553                 goto out;
 554         }
 555         /*
 556          * If the user has closed the socket then drop a persisting
 557          * connection after a much reduced timeout.
 558          */
 559         if (tp->t_state > TCPS_CLOSE_WAIT &&
 560             (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
 561                 TCPSTAT_INC(tcps_persistdrop);
 562                 tp = tcp_drop(tp, ETIMEDOUT);
 563                 goto out;
 564         }
 565         tcp_setpersist(tp);
 566         tp->t_flags |= TF_FORCEDATA;
 567         (void) tcp_output(tp);
 568         tp->t_flags &= ~TF_FORCEDATA;
 569
 570 out:
 571 #ifdef TCPDEBUG
 572         if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
 573                 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
 574 #endif
 575         if (tp != NULL)
 576                 INP_WUNLOCK(inp);
 577         INP_INFO_WUNLOCK(&V_tcbinfo);
 578         CURVNET_RESTORE();
 579 }
 580
 581 void
 582 tcp_timer_rexmt(void * xtp)
 583 {
 584         struct tcpcb *tp = xtp;
 585         CURVNET_SET(tp->t_vnet);
 586         int rexmt;
 587         int headlocked;
 588         struct inpcb *inp;
 589 #ifdef TCPDEBUG
 590         int ostate;
 591
 592         ostate = tp->t_state;
 593 #endif
 594
 595         INP_INFO_RLOCK(&V_tcbinfo);
 596         inp = tp->t_inpcb;
 597         /*
 598          * XXXRW: While this assert is in fact correct, bugs in the tcpcb
 599          * tear-down mean we need it as a work-around for races between
 600          * timers and tcp_discardcb().
 601          *
 602          * KASSERT(inp != NULL, ("tcp_timer_rexmt: inp == NULL"));
 603          */
 604         if (inp == NULL) {
 605                 tcp_timer_race++;
 606                 INP_INFO_RUNLOCK(&V_tcbinfo);
 607                 CURVNET_RESTORE();
 608                 return;
 609         }
 610         INP_WLOCK(inp);
 611         if (callout_pending(&tp->t_timers->tt_rexmt) ||
 612             !callout_active(&tp->t_timers->tt_rexmt)) {
 613                 INP_WUNLOCK(inp);
 614                 INP_INFO_RUNLOCK(&V_tcbinfo);
 615                 CURVNET_RESTORE();
 616                 return;
 617         }
 618         callout_deactivate(&tp->t_timers->tt_rexmt);
 619         if ((inp->inp_flags & INP_DROPPED) != 0) {
 620                 INP_WUNLOCK(inp);
 621                 INP_INFO_RUNLOCK(&V_tcbinfo);
 622                 CURVNET_RESTORE();
 623                 return;
 624         }
 625         tcp_free_sackholes(tp);
 626         /*
 627          * Retransmission timer went off.  Message has not
 628          * been acked within retransmit interval.  Back off
 629          * to a longer retransmit interval and retransmit one segment.
 630          */
 631         if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
 632                 tp->t_rxtshift = TCP_MAXRXTSHIFT;
 633                 TCPSTAT_INC(tcps_timeoutdrop);
 634                 in_pcbref(inp);
 635                 INP_INFO_RUNLOCK(&V_tcbinfo);
 636                 INP_WUNLOCK(inp);
 637                 INP_INFO_WLOCK(&V_tcbinfo);
 638                 INP_WLOCK(inp);
 639                 if (in_pcbrele_wlocked(inp)) {
 640                         INP_INFO_WUNLOCK(&V_tcbinfo);
 641                         CURVNET_RESTORE();
 642                         return;
 643                 }
 644                 if (inp->inp_flags & INP_DROPPED) {
 645                         INP_WUNLOCK(inp);
 646                         INP_INFO_WUNLOCK(&V_tcbinfo);
 647                         CURVNET_RESTORE();
 648                         return;
 649                 }
 650
 651                 tp = tcp_drop(tp, tp->t_softerror ?
 652                               tp->t_softerror : ETIMEDOUT);
 653                 headlocked = 1;
 654                 goto out;
 655         }
 656         INP_INFO_RUNLOCK(&V_tcbinfo);
 657         headlocked = 0;
 658         if (tp->t_state == TCPS_SYN_SENT) {
 659                 /*
 660                  * If the SYN was retransmitted, indicate CWND to be
 661                  * limited to 1 segment in cc_conn_init().
 662                  */
 663                 tp->snd_cwnd = 1;
 664         } else if (tp->t_rxtshift == 1) {
 665                 /*
 666                  * first retransmit; record ssthresh and cwnd so they can
 667                  * be recovered if this turns out to be a "bad" retransmit.
 668                  * A retransmit is considered "bad" if an ACK for this
 669                  * segment is received within RTT/2 interval; the assumption
 670                  * here is that the ACK was already in flight.  See
 671                  * "On Estimating End-to-End Network Path Properties" by
 672                  * Allman and Paxson for more details.
 673                  */
 674                 tp->snd_cwnd_prev = tp->snd_cwnd;
 675                 tp->snd_ssthresh_prev = tp->snd_ssthresh;
 676                 tp->snd_recover_prev = tp->snd_recover;
 677                 if (IN_FASTRECOVERY(tp->t_flags))
 678                         tp->t_flags |= TF_WASFRECOVERY;
 679                 else
 680                         tp->t_flags &= ~TF_WASFRECOVERY;
 681                 if (IN_CONGRECOVERY(tp->t_flags))
 682                         tp->t_flags |= TF_WASCRECOVERY;
 683                 else
 684                         tp->t_flags &= ~TF_WASCRECOVERY;
 685                 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
 686                 tp->t_flags |= TF_PREVVALID;
 687         } else
 688                 tp->t_flags &= ~TF_PREVVALID;
 689         TCPSTAT_INC(tcps_rexmttimeo);
 690         if (tp->t_state == TCPS_SYN_SENT)
 691                 rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift];
 692         else
 693                 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
 694         TCPT_RANGESET(tp->t_rxtcur, rexmt,
 695                       tp->t_rttmin, TCPTV_REXMTMAX);
 696
 697         /*
 698          * We enter the path for PLMTUD if connection is established or, if
 699          * connection is FIN_WAIT_1 status, reason for the last is that if
 700          * amount of data we send is very small, we could send it in couple of
 701          * packets and process straight to FIN. In that case we won't catch
 702          * ESTABLISHED state.
 703          */
 704         if (V_tcp_pmtud_blackhole_detect && (((tp->t_state == TCPS_ESTABLISHED))
 705             || (tp->t_state == TCPS_FIN_WAIT_1))) {
 706                 int optlen;
 707 #ifdef INET6
 708                 int isipv6;
 709 #endif
 710
 711                 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
 712                     (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
 713                     (tp->t_rxtshift <= 2)) {
 714                         /*
 715                          * Enter Path MTU Black-hole Detection mechanism:
 716                          * - Disable Path MTU Discovery (IP "DF" bit).
 717                          * - Reduce MTU to lower value than what we
 718                          *   negotiated with peer.
 719                          */
 720                         /* Record that we may have found a black hole. */
 721                         tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
 722
 723                         /* Keep track of previous MSS. */
 724                         optlen = tp->t_maxopd - tp->t_maxseg;
 725                         tp->t_pmtud_saved_maxopd = tp->t_maxopd;
 726
 727                         /*
 728                          * Reduce the MSS to blackhole value or to the default
 729                          * in an attempt to retransmit.
 730                          */
 731 #ifdef INET6
 732                         isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? 1 : 0;
 733                         if (isipv6 &&
 734                             tp->t_maxopd > V_tcp_v6pmtud_blackhole_mss) {
 735                                 /* Use the sysctl tuneable blackhole MSS. */
 736                                 tp->t_maxopd = V_tcp_v6pmtud_blackhole_mss;
 737                                 V_tcp_pmtud_blackhole_activated++;
 738                         } else if (isipv6) {
 739                                 /* Use the default MSS. */
 740                                 tp->t_maxopd = V_tcp_v6mssdflt;
 741                                 /*
 742                                  * Disable Path MTU Discovery when we switch to
 743                                  * minmss.
 744                                  */
 745                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 746                                 V_tcp_pmtud_blackhole_activated_min_mss++;
 747                         }
 748 #endif
 749 #if defined(INET6) && defined(INET)
 750                         else
 751 #endif
 752 #ifdef INET
 753                         if (tp->t_maxopd > V_tcp_pmtud_blackhole_mss) {
 754                                 /* Use the sysctl tuneable blackhole MSS. */
 755                                 tp->t_maxopd = V_tcp_pmtud_blackhole_mss;
 756                                 V_tcp_pmtud_blackhole_activated++;
 757                         } else {
 758                                 /* Use the default MSS. */
 759                                 tp->t_maxopd = V_tcp_mssdflt;
 760                                 /*
 761                                  * Disable Path MTU Discovery when we switch to
 762                                  * minmss.
 763                                  */
 764                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 765                                 V_tcp_pmtud_blackhole_activated_min_mss++;
 766                         }
 767 #endif
 768                         tp->t_maxseg = tp->t_maxopd - optlen;
 769                         /*
 770                          * Reset the slow-start flight size
 771                          * as it may depend on the new MSS.
 772                          */
 773                         if (CC_ALGO(tp)->conn_init != NULL)
 774                                 CC_ALGO(tp)->conn_init(tp->ccv);
 775                 } else {
 776                         /*
 777                          * If further retransmissions are still unsuccessful
 778                          * with a lowered MTU, maybe this isn't a blackhole and
 779                          * we restore the previous MSS and blackhole detection
 780                          * flags.
 781                          */
 782                         if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
 783                             (tp->t_rxtshift > 4)) {
 784                                 tp->t_flags2 |= TF2_PLPMTU_PMTUD;
 785                                 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
 786                                 optlen = tp->t_maxopd - tp->t_maxseg;
 787                                 tp->t_maxopd = tp->t_pmtud_saved_maxopd;
 788                                 tp->t_maxseg = tp->t_maxopd - optlen;
 789                                 V_tcp_pmtud_blackhole_failed++;
 790                                 /*
 791                                  * Reset the slow-start flight size as it
 792                                  * may depend on the new MSS.
 793                                  */
 794                                 if (CC_ALGO(tp)->conn_init != NULL)
 795                                         CC_ALGO(tp)->conn_init(tp->ccv);
 796                         }
 797                 }
 798         }
 799
 800         /*
 801          * Disable RFC1323 and SACK if we haven't got any response to
 802          * our third SYN to work-around some broken terminal servers
 803          * (most of which have hopefully been retired) that have bad VJ
 804          * header compression code which trashes TCP segments containing
 805          * unknown-to-them TCP options.
 806          */
 807         if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
 808             (tp->t_rxtshift == 3))
 809                 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
 810         /*
 811          * If we backed off this far, our srtt estimate is probably bogus.
 812          * Clobber it so we'll take the next rtt measurement as our srtt;
 813          * move the current srtt into rttvar to keep the current
 814          * retransmit times until then.
 815          */
 816         if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
 817 #ifdef INET6
 818                 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
 819                         in6_losing(tp->t_inpcb);
 820 #endif
 821                 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
 822                 tp->t_srtt = 0;
 823         }
 824         tp->snd_nxt = tp->snd_una;
 825         tp->snd_recover = tp->snd_max;
 826         /*
 827          * Force a segment to be sent.
 828          */
 829         tp->t_flags |= TF_ACKNOW;
 830         /*
 831          * If timing a segment in this window, stop the timer.
 832          */
 833         tp->t_rtttime = 0;
 834
 835         cc_cong_signal(tp, NULL, CC_RTO);
 836
 837         (void) tcp_output(tp);
 838
 839 out:
 840 #ifdef TCPDEBUG
 841         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 842                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 843                           PRU_SLOWTIMO);
 844 #endif
 845         if (tp != NULL)
 846                 INP_WUNLOCK(inp);
 847         if (headlocked)
 848                 INP_INFO_WUNLOCK(&V_tcbinfo);
 849         CURVNET_RESTORE();
 850 }
 851
 852 void
 853 tcp_timer_activate(struct tcpcb *tp, int timer_type, u_int delta)
 854 {
 855         struct callout *t_callout;
 856         void *f_callout;
 857         struct inpcb *inp = tp->t_inpcb;
 858         int cpu = inp_to_cpuid(inp);
 859
 860 #ifdef TCP_OFFLOAD
 861         if (tp->t_flags & TF_TOE)
 862                 return;
 863 #endif
 864
 865         switch (timer_type) {
 866                 case TT_DELACK:
 867                         t_callout = &tp->t_timers->tt_delack;
 868                         f_callout = tcp_timer_delack;
 869                         break;
 870                 case TT_REXMT:
 871                         t_callout = &tp->t_timers->tt_rexmt;
 872                         f_callout = tcp_timer_rexmt;
 873                         break;
 874                 case TT_PERSIST:
 875                         t_callout = &tp->t_timers->tt_persist;
 876                         f_callout = tcp_timer_persist;
 877                         break;
 878                 case TT_KEEP:
 879                         t_callout = &tp->t_timers->tt_keep;
 880                         f_callout = tcp_timer_keep;
 881                         break;
 882                 case TT_2MSL:
 883                         t_callout = &tp->t_timers->tt_2msl;
 884                         f_callout = tcp_timer_2msl;
 885                         break;
 886                 default:
 887                         panic("bad timer_type");
 888                 }
 889         if (delta == 0) {
 890                 callout_stop(t_callout);
 891         } else {
 892                 callout_reset_on(t_callout, delta, f_callout, tp, cpu);
 893         }
 894 }
 895
 896 int
 897 tcp_timer_active(struct tcpcb *tp, int timer_type)
 898 {
 899         struct callout *t_callout;
 900
 901         switch (timer_type) {
 902                 case TT_DELACK:
 903                         t_callout = &tp->t_timers->tt_delack;
 904                         break;
 905                 case TT_REXMT:
 906                         t_callout = &tp->t_timers->tt_rexmt;
 907                         break;
 908                 case TT_PERSIST:
 909                         t_callout = &tp->t_timers->tt_persist;
 910                         break;
 911                 case TT_KEEP:
 912                         t_callout = &tp->t_timers->tt_keep;
 913                         break;
 914                 case TT_2MSL:
 915                         t_callout = &tp->t_timers->tt_2msl;
 916                         break;
 917                 default:
 918                         panic("bad timer_type");
 919                 }
 920         return callout_active(t_callout);
 921 }
 922
 923 #define ticks_to_msecs(t)       (1000*(t) / hz)
 924
 925 void
 926 tcp_timer_to_xtimer(struct tcpcb *tp, struct tcp_timer *timer,
 927     struct xtcp_timer *xtimer)
 928 {
 929         sbintime_t now;
 930
 931         bzero(xtimer, sizeof(*xtimer));
 932         if (timer == NULL)
 933                 return;
 934         now = getsbinuptime();
 935         if (callout_active(&timer->tt_delack))
 936                 xtimer->tt_delack = (timer->tt_delack.c_time - now) / SBT_1MS;
 937         if (callout_active(&timer->tt_rexmt))
 938                 xtimer->tt_rexmt = (timer->tt_rexmt.c_time - now) / SBT_1MS;
 939         if (callout_active(&timer->tt_persist))
 940                 xtimer->tt_persist = (timer->tt_persist.c_time - now) / SBT_1MS;
 941         if (callout_active(&timer->tt_keep))
 942                 xtimer->tt_keep = (timer->tt_keep.c_time - now) / SBT_1MS;
 943         if (callout_active(&timer->tt_2msl))
 944                 xtimer->tt_2msl = (timer->tt_2msl.c_time - now) / SBT_1MS;
 945         xtimer->t_rcvtime = ticks_to_msecs(ticks - tp->t_rcvtime);
 946 }