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/in.h>
  59 #include <netinet/in_kdtrace.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.h>
  68 #include <netinet/tcp_fsm.h>
  69 #include <netinet/tcp_timer.h>
  70 #include <netinet/tcp_var.h>
  71 #include <netinet/cc/cc.h>
  72 #ifdef INET6
  73 #include <netinet6/tcp6_var.h>
  74 #endif
  75 #include <netinet/tcpip.h>
  76 #ifdef TCPDEBUG
  77 #include <netinet/tcp_debug.h>
  78 #endif
  79
  80 int    tcp_persmin;
  81 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmin, CTLTYPE_INT|CTLFLAG_RW,
  82     &tcp_persmin, 0, sysctl_msec_to_ticks, "I", "minimum persistence interval");
  83
  84 int    tcp_persmax;
  85 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmax, CTLTYPE_INT|CTLFLAG_RW,
  86     &tcp_persmax, 0, sysctl_msec_to_ticks, "I", "maximum persistence interval");
  87
  88 int     tcp_keepinit;
  89 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
  90     &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "time to establish connection");
  91
  92 int     tcp_keepidle;
  93 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
  94     &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "time before keepalive probes begin");
  95
  96 int     tcp_keepintvl;
  97 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
  98     &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "time between keepalive probes");
  99
 100 int     tcp_delacktime;
 101 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW,
 102     &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
 103     "Time before a delayed ACK is sent");
 104
 105 int     tcp_msl;
 106 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
 107     &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
 108
 109 int     tcp_rexmit_min;
 110 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
 111     &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
 112     "Minimum Retransmission Timeout");
 113
 114 int     tcp_rexmit_slop;
 115 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
 116     &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
 117     "Retransmission Timer Slop");
 118
 119 static int      always_keepalive = 1;
 120 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW,
 121     &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections");
 122
 123 int    tcp_fast_finwait2_recycle = 0;
 124 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
 125     &tcp_fast_finwait2_recycle, 0,
 126     "Recycle closed FIN_WAIT_2 connections faster");
 127
 128 int    tcp_finwait2_timeout;
 129 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW,
 130     &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout");
 131
 132 int     tcp_keepcnt = TCPTV_KEEPCNT;
 133 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
 134     "Number of keepalive probes to send");
 135
 136         /* max idle probes */
 137 int     tcp_maxpersistidle;
 138
 139 static int      tcp_rexmit_drop_options = 0;
 140 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
 141     &tcp_rexmit_drop_options, 0,
 142     "Drop TCP options from 3rd and later retransmitted SYN");
 143
 144 static VNET_DEFINE(int, tcp_pmtud_blackhole_detect);
 145 #define V_tcp_pmtud_blackhole_detect    VNET(tcp_pmtud_blackhole_detect)
 146 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection,
 147     CTLFLAG_RW|CTLFLAG_VNET,
 148     &VNET_NAME(tcp_pmtud_blackhole_detect), 0,
 149     "Path MTU Discovery Black Hole Detection Enabled");
 150
 151 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated);
 152 #define V_tcp_pmtud_blackhole_activated \
 153     VNET(tcp_pmtud_blackhole_activated)
 154 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated,
 155     CTLFLAG_RD|CTLFLAG_VNET,
 156     &VNET_NAME(tcp_pmtud_blackhole_activated), 0,
 157     "Path MTU Discovery Black Hole Detection, Activation Count");
 158
 159 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated_min_mss);
 160 #define V_tcp_pmtud_blackhole_activated_min_mss \
 161     VNET(tcp_pmtud_blackhole_activated_min_mss)
 162 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated_min_mss,
 163     CTLFLAG_RD|CTLFLAG_VNET,
 164     &VNET_NAME(tcp_pmtud_blackhole_activated_min_mss), 0,
 165     "Path MTU Discovery Black Hole Detection, Activation Count at min MSS");
 166
 167 static VNET_DEFINE(int, tcp_pmtud_blackhole_failed);
 168 #define V_tcp_pmtud_blackhole_failed    VNET(tcp_pmtud_blackhole_failed)
 169 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_failed,
 170     CTLFLAG_RD|CTLFLAG_VNET,
 171     &VNET_NAME(tcp_pmtud_blackhole_failed), 0,
 172     "Path MTU Discovery Black Hole Detection, Failure Count");
 173
 174 #ifdef INET
 175 static VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200;
 176 #define V_tcp_pmtud_blackhole_mss       VNET(tcp_pmtud_blackhole_mss)
 177 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss,
 178     CTLFLAG_RW|CTLFLAG_VNET,
 179     &VNET_NAME(tcp_pmtud_blackhole_mss), 0,
 180     "Path MTU Discovery Black Hole Detection lowered MSS");
 181 #endif
 182
 183 #ifdef INET6
 184 static VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220;
 185 #define V_tcp_v6pmtud_blackhole_mss     VNET(tcp_v6pmtud_blackhole_mss)
 186 SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss,
 187     CTLFLAG_RW|CTLFLAG_VNET,
 188     &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0,
 189     "Path MTU Discovery IPv6 Black Hole Detection lowered MSS");
 190 #endif
 191
 192 #ifdef  RSS
 193 static int      per_cpu_timers = 1;
 194 #else
 195 static int      per_cpu_timers = 0;
 196 #endif
 197 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
 198     &per_cpu_timers , 0, "run tcp timers on all cpus");
 199
 200 #if 0
 201 #define INP_CPU(inp)    (per_cpu_timers ? (!CPU_ABSENT(((inp)->inp_flowid % (mp_maxid+1))) ? \
 202                 ((inp)->inp_flowid % (mp_maxid+1)) : curcpu) : 0)
 203 #endif
 204
 205 /*
 206  * Map the given inp to a CPU id.
 207  *
 208  * This queries RSS if it's compiled in, else it defaults to the current
 209  * CPU ID.
 210  */
 211 static inline int
 212 inp_to_cpuid(struct inpcb *inp)
 213 {
 214         u_int cpuid;
 215
 216 #ifdef  RSS
 217         if (per_cpu_timers) {
 218                 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
 219                 if (cpuid == NETISR_CPUID_NONE)
 220                         return (curcpu);        /* XXX */
 221                 else
 222                         return (cpuid);
 223         }
 224 #else
 225         /* Legacy, pre-RSS behaviour */
 226         if (per_cpu_timers) {
 227                 /*
 228                  * We don't have a flowid -> cpuid mapping, so cheat and
 229                  * just map unknown cpuids to curcpu.  Not the best, but
 230                  * apparently better than defaulting to swi 0.
 231                  */
 232                 cpuid = inp->inp_flowid % (mp_maxid + 1);
 233                 if (! CPU_ABSENT(cpuid))
 234                         return (cpuid);
 235                 return (curcpu);
 236         }
 237 #endif
 238         /* Default for RSS and non-RSS - cpuid 0 */
 239         else {
 240                 return (0);
 241         }
 242 }
 243
 244 /*
 245  * Tcp protocol timeout routine called every 500 ms.
 246  * Updates timestamps used for TCP
 247  * causes finite state machine actions if timers expire.
 248  */
 249 void
 250 tcp_slowtimo(void)
 251 {
 252         VNET_ITERATOR_DECL(vnet_iter);
 253
 254         VNET_LIST_RLOCK_NOSLEEP();
 255         VNET_FOREACH(vnet_iter) {
 256                 CURVNET_SET(vnet_iter);
 257                 (void) tcp_tw_2msl_scan(0);
 258                 CURVNET_RESTORE();
 259         }
 260         VNET_LIST_RUNLOCK_NOSLEEP();
 261 }
 262
 263 int     tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] =
 264     { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 };
 265
 266 int     tcp_backoff[TCP_MAXRXTSHIFT + 1] =
 267     { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
 268
 269 static int tcp_totbackoff = 2559;       /* sum of tcp_backoff[] */
 270
 271 /*
 272  * TCP timer processing.
 273  */
 274
 275 void
 276 tcp_timer_delack(void *xtp)
 277 {
 278         struct tcpcb *tp = xtp;
 279         struct inpcb *inp;
 280         CURVNET_SET(tp->t_vnet);
 281
 282         inp = tp->t_inpcb;
 283         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 284         INP_WLOCK(inp);
 285         if (callout_pending(&tp->t_timers->tt_delack) ||
 286             !callout_active(&tp->t_timers->tt_delack)) {
 287                 INP_WUNLOCK(inp);
 288                 CURVNET_RESTORE();
 289                 return;
 290         }
 291         callout_deactivate(&tp->t_timers->tt_delack);
 292         if ((inp->inp_flags & INP_DROPPED) != 0) {
 293                 INP_WUNLOCK(inp);
 294                 CURVNET_RESTORE();
 295                 return;
 296         }
 297         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 298                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 299         KASSERT((tp->t_timers->tt_flags & TT_DELACK) != 0,
 300                 ("%s: tp %p delack callout should be running", __func__, tp));
 301
 302         tp->t_flags |= TF_ACKNOW;
 303         TCPSTAT_INC(tcps_delack);
 304         (void) tp->t_fb->tfb_tcp_output(tp);
 305         INP_WUNLOCK(inp);
 306         CURVNET_RESTORE();
 307 }
 308
 309 void
 310 tcp_timer_2msl(void *xtp)
 311 {
 312         struct tcpcb *tp = xtp;
 313         struct inpcb *inp;
 314         CURVNET_SET(tp->t_vnet);
 315 #ifdef TCPDEBUG
 316         int ostate;
 317
 318         ostate = tp->t_state;
 319 #endif
 320         INP_INFO_RLOCK(&V_tcbinfo);
 321         inp = tp->t_inpcb;
 322         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 323         INP_WLOCK(inp);
 324         tcp_free_sackholes(tp);
 325         if (callout_pending(&tp->t_timers->tt_2msl) ||
 326             !callout_active(&tp->t_timers->tt_2msl)) {
 327                 INP_WUNLOCK(tp->t_inpcb);
 328                 INP_INFO_RUNLOCK(&V_tcbinfo);
 329                 CURVNET_RESTORE();
 330                 return;
 331         }
 332         callout_deactivate(&tp->t_timers->tt_2msl);
 333         if ((inp->inp_flags & INP_DROPPED) != 0) {
 334                 INP_WUNLOCK(inp);
 335                 INP_INFO_RUNLOCK(&V_tcbinfo);
 336                 CURVNET_RESTORE();
 337                 return;
 338         }
 339         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 340                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 341         KASSERT((tp->t_timers->tt_flags & TT_2MSL) != 0,
 342                 ("%s: tp %p 2msl callout should be running", __func__, tp));
 343         /*
 344          * 2 MSL timeout in shutdown went off.  If we're closed but
 345          * still waiting for peer to close and connection has been idle
 346          * too long delete connection control block.  Otherwise, check
 347          * again in a bit.
 348          *
 349          * If in TIME_WAIT state just ignore as this timeout is handled in
 350          * tcp_tw_2msl_scan().
 351          *
 352          * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
 353          * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
 354          * Ignore fact that there were recent incoming segments.
 355          */
 356         if ((inp->inp_flags & INP_TIMEWAIT) != 0) {
 357                 INP_WUNLOCK(inp);
 358                 INP_INFO_RUNLOCK(&V_tcbinfo);
 359                 CURVNET_RESTORE();
 360                 return;
 361         }
 362         if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
 363             tp->t_inpcb && tp->t_inpcb->inp_socket &&
 364             (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
 365                 TCPSTAT_INC(tcps_finwait2_drops);
 366                 tp = tcp_close(tp);
 367         } else {
 368                 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) {
 369                         if (!callout_reset(&tp->t_timers->tt_2msl,
 370                            TP_KEEPINTVL(tp), tcp_timer_2msl, tp)) {
 371                                 tp->t_timers->tt_flags &= ~TT_2MSL_RST;
 372                         }
 373                 } else
 374                        tp = tcp_close(tp);
 375        }
 376
 377 #ifdef TCPDEBUG
 378         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 379                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 380                           PRU_SLOWTIMO);
 381 #endif
 382         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 383
 384         if (tp != NULL)
 385                 INP_WUNLOCK(inp);
 386         INP_INFO_RUNLOCK(&V_tcbinfo);
 387         CURVNET_RESTORE();
 388 }
 389
 390 void
 391 tcp_timer_keep(void *xtp)
 392 {
 393         struct tcpcb *tp = xtp;
 394         struct tcptemp *t_template;
 395         struct inpcb *inp;
 396         CURVNET_SET(tp->t_vnet);
 397 #ifdef TCPDEBUG
 398         int ostate;
 399
 400         ostate = tp->t_state;
 401 #endif
 402         INP_INFO_RLOCK(&V_tcbinfo);
 403         inp = tp->t_inpcb;
 404         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 405         INP_WLOCK(inp);
 406         if (callout_pending(&tp->t_timers->tt_keep) ||
 407             !callout_active(&tp->t_timers->tt_keep)) {
 408                 INP_WUNLOCK(inp);
 409                 INP_INFO_RUNLOCK(&V_tcbinfo);
 410                 CURVNET_RESTORE();
 411                 return;
 412         }
 413         callout_deactivate(&tp->t_timers->tt_keep);
 414         if ((inp->inp_flags & INP_DROPPED) != 0) {
 415                 INP_WUNLOCK(inp);
 416                 INP_INFO_RUNLOCK(&V_tcbinfo);
 417                 CURVNET_RESTORE();
 418                 return;
 419         }
 420         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 421                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 422         KASSERT((tp->t_timers->tt_flags & TT_KEEP) != 0,
 423                 ("%s: tp %p keep callout should be running", __func__, tp));
 424         /*
 425          * Keep-alive timer went off; send something
 426          * or drop connection if idle for too long.
 427          */
 428         TCPSTAT_INC(tcps_keeptimeo);
 429         if (tp->t_state < TCPS_ESTABLISHED)
 430                 goto dropit;
 431         if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) &&
 432             tp->t_state <= TCPS_CLOSING) {
 433                 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
 434                         goto dropit;
 435                 /*
 436                  * Send a packet designed to force a response
 437                  * if the peer is up and reachable:
 438                  * either an ACK if the connection is still alive,
 439                  * or an RST if the peer has closed the connection
 440                  * due to timeout or reboot.
 441                  * Using sequence number tp->snd_una-1
 442                  * causes the transmitted zero-length segment
 443                  * to lie outside the receive window;
 444                  * by the protocol spec, this requires the
 445                  * correspondent TCP to respond.
 446                  */
 447                 TCPSTAT_INC(tcps_keepprobe);
 448                 t_template = tcpip_maketemplate(inp);
 449                 if (t_template) {
 450                         tcp_respond(tp, t_template->tt_ipgen,
 451                                     &t_template->tt_t, (struct mbuf *)NULL,
 452                                     tp->rcv_nxt, tp->snd_una - 1, 0);
 453                         free(t_template, M_TEMP);
 454                 }
 455                 if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
 456                     tcp_timer_keep, tp)) {
 457                         tp->t_timers->tt_flags &= ~TT_KEEP_RST;
 458                 }
 459         } else if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
 460                     tcp_timer_keep, tp)) {
 461                         tp->t_timers->tt_flags &= ~TT_KEEP_RST;
 462                 }
 463
 464 #ifdef TCPDEBUG
 465         if (inp->inp_socket->so_options & SO_DEBUG)
 466                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 467                           PRU_SLOWTIMO);
 468 #endif
 469         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 470         INP_WUNLOCK(inp);
 471         INP_INFO_RUNLOCK(&V_tcbinfo);
 472         CURVNET_RESTORE();
 473         return;
 474
 475 dropit:
 476         TCPSTAT_INC(tcps_keepdrops);
 477         tp = tcp_drop(tp, ETIMEDOUT);
 478
 479 #ifdef TCPDEBUG
 480         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 481                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 482                           PRU_SLOWTIMO);
 483 #endif
 484         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 485         if (tp != NULL)
 486                 INP_WUNLOCK(tp->t_inpcb);
 487         INP_INFO_RUNLOCK(&V_tcbinfo);
 488         CURVNET_RESTORE();
 489 }
 490
 491 void
 492 tcp_timer_persist(void *xtp)
 493 {
 494         struct tcpcb *tp = xtp;
 495         struct inpcb *inp;
 496         CURVNET_SET(tp->t_vnet);
 497 #ifdef TCPDEBUG
 498         int ostate;
 499
 500         ostate = tp->t_state;
 501 #endif
 502         INP_INFO_RLOCK(&V_tcbinfo);
 503         inp = tp->t_inpcb;
 504         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 505         INP_WLOCK(inp);
 506         if (callout_pending(&tp->t_timers->tt_persist) ||
 507             !callout_active(&tp->t_timers->tt_persist)) {
 508                 INP_WUNLOCK(inp);
 509                 INP_INFO_RUNLOCK(&V_tcbinfo);
 510                 CURVNET_RESTORE();
 511                 return;
 512         }
 513         callout_deactivate(&tp->t_timers->tt_persist);
 514         if ((inp->inp_flags & INP_DROPPED) != 0) {
 515                 INP_WUNLOCK(inp);
 516                 INP_INFO_RUNLOCK(&V_tcbinfo);
 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         KASSERT((tp->t_timers->tt_flags & TT_PERSIST) != 0,
 523                 ("%s: tp %p persist callout should be running", __func__, tp));
 524         /*
 525          * Persistence timer into zero window.
 526          * Force a byte to be output, if possible.
 527          */
 528         TCPSTAT_INC(tcps_persisttimeo);
 529         /*
 530          * Hack: if the peer is dead/unreachable, we do not
 531          * time out if the window is closed.  After a full
 532          * backoff, drop the connection if the idle time
 533          * (no responses to probes) reaches the maximum
 534          * backoff that we would use if retransmitting.
 535          */
 536         if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
 537             (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
 538              ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
 539                 TCPSTAT_INC(tcps_persistdrop);
 540                 tp = tcp_drop(tp, ETIMEDOUT);
 541                 goto out;
 542         }
 543         /*
 544          * If the user has closed the socket then drop a persisting
 545          * connection after a much reduced timeout.
 546          */
 547         if (tp->t_state > TCPS_CLOSE_WAIT &&
 548             (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
 549                 TCPSTAT_INC(tcps_persistdrop);
 550                 tp = tcp_drop(tp, ETIMEDOUT);
 551                 goto out;
 552         }
 553         tcp_setpersist(tp);
 554         tp->t_flags |= TF_FORCEDATA;
 555         (void) tp->t_fb->tfb_tcp_output(tp);
 556         tp->t_flags &= ~TF_FORCEDATA;
 557
 558 out:
 559 #ifdef TCPDEBUG
 560         if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
 561                 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
 562 #endif
 563         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 564         if (tp != NULL)
 565                 INP_WUNLOCK(inp);
 566         INP_INFO_RUNLOCK(&V_tcbinfo);
 567         CURVNET_RESTORE();
 568 }
 569
 570 void
 571 tcp_timer_rexmt(void * xtp)
 572 {
 573         struct tcpcb *tp = xtp;
 574         CURVNET_SET(tp->t_vnet);
 575         int rexmt;
 576         int headlocked;
 577         struct inpcb *inp;
 578 #ifdef TCPDEBUG
 579         int ostate;
 580
 581         ostate = tp->t_state;
 582 #endif
 583
 584         INP_INFO_RLOCK(&V_tcbinfo);
 585         inp = tp->t_inpcb;
 586         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 587         INP_WLOCK(inp);
 588         if (callout_pending(&tp->t_timers->tt_rexmt) ||
 589             !callout_active(&tp->t_timers->tt_rexmt)) {
 590                 INP_WUNLOCK(inp);
 591                 INP_INFO_RUNLOCK(&V_tcbinfo);
 592                 CURVNET_RESTORE();
 593                 return;
 594         }
 595         callout_deactivate(&tp->t_timers->tt_rexmt);
 596         if ((inp->inp_flags & INP_DROPPED) != 0) {
 597                 INP_WUNLOCK(inp);
 598                 INP_INFO_RUNLOCK(&V_tcbinfo);
 599                 CURVNET_RESTORE();
 600                 return;
 601         }
 602         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 603                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 604         KASSERT((tp->t_timers->tt_flags & TT_REXMT) != 0,
 605                 ("%s: tp %p rexmt callout should be running", __func__, tp));
 606         tcp_free_sackholes(tp);
 607         /*
 608          * Retransmission timer went off.  Message has not
 609          * been acked within retransmit interval.  Back off
 610          * to a longer retransmit interval and retransmit one segment.
 611          */
 612         if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
 613                 tp->t_rxtshift = TCP_MAXRXTSHIFT;
 614                 TCPSTAT_INC(tcps_timeoutdrop);
 615
 616                 tp = tcp_drop(tp, tp->t_softerror ?
 617                               tp->t_softerror : ETIMEDOUT);
 618                 headlocked = 1;
 619                 goto out;
 620         }
 621         INP_INFO_RUNLOCK(&V_tcbinfo);
 622         headlocked = 0;
 623         if (tp->t_state == TCPS_SYN_SENT) {
 624                 /*
 625                  * If the SYN was retransmitted, indicate CWND to be
 626                  * limited to 1 segment in cc_conn_init().
 627                  */
 628                 tp->snd_cwnd = 1;
 629         } else if (tp->t_rxtshift == 1) {
 630                 /*
 631                  * first retransmit; record ssthresh and cwnd so they can
 632                  * be recovered if this turns out to be a "bad" retransmit.
 633                  * A retransmit is considered "bad" if an ACK for this
 634                  * segment is received within RTT/2 interval; the assumption
 635                  * here is that the ACK was already in flight.  See
 636                  * "On Estimating End-to-End Network Path Properties" by
 637                  * Allman and Paxson for more details.
 638                  */
 639                 tp->snd_cwnd_prev = tp->snd_cwnd;
 640                 tp->snd_ssthresh_prev = tp->snd_ssthresh;
 641                 tp->snd_recover_prev = tp->snd_recover;
 642                 if (IN_FASTRECOVERY(tp->t_flags))
 643                         tp->t_flags |= TF_WASFRECOVERY;
 644                 else
 645                         tp->t_flags &= ~TF_WASFRECOVERY;
 646                 if (IN_CONGRECOVERY(tp->t_flags))
 647                         tp->t_flags |= TF_WASCRECOVERY;
 648                 else
 649                         tp->t_flags &= ~TF_WASCRECOVERY;
 650                 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
 651                 tp->t_flags |= TF_PREVVALID;
 652         } else
 653                 tp->t_flags &= ~TF_PREVVALID;
 654         TCPSTAT_INC(tcps_rexmttimeo);
 655         if ((tp->t_state == TCPS_SYN_SENT) ||
 656             (tp->t_state == TCPS_SYN_RECEIVED))
 657                 rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift];
 658         else
 659                 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
 660         TCPT_RANGESET(tp->t_rxtcur, rexmt,
 661                       tp->t_rttmin, TCPTV_REXMTMAX);
 662
 663         /*
 664          * We enter the path for PLMTUD if connection is established or, if
 665          * connection is FIN_WAIT_1 status, reason for the last is that if
 666          * amount of data we send is very small, we could send it in couple of
 667          * packets and process straight to FIN. In that case we won't catch
 668          * ESTABLISHED state.
 669          */
 670         if (V_tcp_pmtud_blackhole_detect && (((tp->t_state == TCPS_ESTABLISHED))
 671             || (tp->t_state == TCPS_FIN_WAIT_1))) {
 672 #ifdef INET6
 673                 int isipv6;
 674 #endif
 675
 676                 /*
 677                  * Idea here is that at each stage of mtu probe (usually, 1448
 678                  * -> 1188 -> 524) should be given 2 chances to recover before
 679                  *  further clamping down. 'tp->t_rxtshift % 2 == 0' should
 680                  *  take care of that.
 681                  */
 682                 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
 683                     (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
 684                     (tp->t_rxtshift >= 2 && tp->t_rxtshift % 2 == 0)) {
 685                         /*
 686                          * Enter Path MTU Black-hole Detection mechanism:
 687                          * - Disable Path MTU Discovery (IP "DF" bit).
 688                          * - Reduce MTU to lower value than what we
 689                          *   negotiated with peer.
 690                          */
 691                         /* Record that we may have found a black hole. */
 692                         tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
 693
 694                         /* Keep track of previous MSS. */
 695                         tp->t_pmtud_saved_maxseg = tp->t_maxseg;
 696
 697                         /*
 698                          * Reduce the MSS to blackhole value or to the default
 699                          * in an attempt to retransmit.
 700                          */
 701 #ifdef INET6
 702                         isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? 1 : 0;
 703                         if (isipv6 &&
 704                             tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss) {
 705                                 /* Use the sysctl tuneable blackhole MSS. */
 706                                 tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss;
 707                                 V_tcp_pmtud_blackhole_activated++;
 708                         } else if (isipv6) {
 709                                 /* Use the default MSS. */
 710                                 tp->t_maxseg = V_tcp_v6mssdflt;
 711                                 /*
 712                                  * Disable Path MTU Discovery when we switch to
 713                                  * minmss.
 714                                  */
 715                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 716                                 V_tcp_pmtud_blackhole_activated_min_mss++;
 717                         }
 718 #endif
 719 #if defined(INET6) && defined(INET)
 720                         else
 721 #endif
 722 #ifdef INET
 723                         if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss) {
 724                                 /* Use the sysctl tuneable blackhole MSS. */
 725                                 tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
 726                                 V_tcp_pmtud_blackhole_activated++;
 727                         } else {
 728                                 /* Use the default MSS. */
 729                                 tp->t_maxseg = V_tcp_mssdflt;
 730                                 /*
 731                                  * Disable Path MTU Discovery when we switch to
 732                                  * minmss.
 733                                  */
 734                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 735                                 V_tcp_pmtud_blackhole_activated_min_mss++;
 736                         }
 737 #endif
 738                         /*
 739                          * Reset the slow-start flight size
 740                          * as it may depend on the new MSS.
 741                          */
 742                         if (CC_ALGO(tp)->conn_init != NULL)
 743                                 CC_ALGO(tp)->conn_init(tp->ccv);
 744                 } else {
 745                         /*
 746                          * If further retransmissions are still unsuccessful
 747                          * with a lowered MTU, maybe this isn't a blackhole and
 748                          * we restore the previous MSS and blackhole detection
 749                          * flags.
 750                          * The limit '6' is determined by giving each probe
 751                          * stage (1448, 1188, 524) 2 chances to recover.
 752                          */
 753                         if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
 754                             (tp->t_rxtshift > 6)) {
 755                                 tp->t_flags2 |= TF2_PLPMTU_PMTUD;
 756                                 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
 757                                 tp->t_maxseg = tp->t_pmtud_saved_maxseg;
 758                                 V_tcp_pmtud_blackhole_failed++;
 759                                 /*
 760                                  * Reset the slow-start flight size as it
 761                                  * may depend on the new MSS.
 762                                  */
 763                                 if (CC_ALGO(tp)->conn_init != NULL)
 764                                         CC_ALGO(tp)->conn_init(tp->ccv);
 765                         }
 766                 }
 767         }
 768
 769         /*
 770          * Disable RFC1323 and SACK if we haven't got any response to
 771          * our third SYN to work-around some broken terminal servers
 772          * (most of which have hopefully been retired) that have bad VJ
 773          * header compression code which trashes TCP segments containing
 774          * unknown-to-them TCP options.
 775          */
 776         if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
 777             (tp->t_rxtshift == 3))
 778                 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
 779         /*
 780          * If we backed off this far, our srtt estimate is probably bogus.
 781          * Clobber it so we'll take the next rtt measurement as our srtt;
 782          * move the current srtt into rttvar to keep the current
 783          * retransmit times until then.
 784          */
 785         if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
 786 #ifdef INET6
 787                 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
 788                         in6_losing(tp->t_inpcb);
 789                 else
 790 #endif
 791                         in_losing(tp->t_inpcb);
 792                 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
 793                 tp->t_srtt = 0;
 794         }
 795         tp->snd_nxt = tp->snd_una;
 796         tp->snd_recover = tp->snd_max;
 797         /*
 798          * Force a segment to be sent.
 799          */
 800         tp->t_flags |= TF_ACKNOW;
 801         /*
 802          * If timing a segment in this window, stop the timer.
 803          */
 804         tp->t_rtttime = 0;
 805
 806         cc_cong_signal(tp, NULL, CC_RTO);
 807
 808         (void) tp->t_fb->tfb_tcp_output(tp);
 809
 810 out:
 811 #ifdef TCPDEBUG
 812         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 813                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 814                           PRU_SLOWTIMO);
 815 #endif
 816         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 817         if (tp != NULL)
 818                 INP_WUNLOCK(inp);
 819         if (headlocked)
 820                 INP_INFO_RUNLOCK(&V_tcbinfo);
 821         CURVNET_RESTORE();
 822 }
 823
 824 void
 825 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
 826 {
 827         struct callout *t_callout;
 828         timeout_t *f_callout;
 829         struct inpcb *inp = tp->t_inpcb;
 830         int cpu = inp_to_cpuid(inp);
 831         uint32_t f_reset;
 832
 833 #ifdef TCP_OFFLOAD
 834         if (tp->t_flags & TF_TOE)
 835                 return;
 836 #endif
 837
 838         if (tp->t_timers->tt_flags & TT_STOPPED)
 839                 return;
 840
 841         switch (timer_type) {
 842                 case TT_DELACK:
 843                         t_callout = &tp->t_timers->tt_delack;
 844                         f_callout = tcp_timer_delack;
 845                         f_reset = TT_DELACK_RST;
 846                         break;
 847                 case TT_REXMT:
 848                         t_callout = &tp->t_timers->tt_rexmt;
 849                         f_callout = tcp_timer_rexmt;
 850                         f_reset = TT_REXMT_RST;
 851                         break;
 852                 case TT_PERSIST:
 853                         t_callout = &tp->t_timers->tt_persist;
 854                         f_callout = tcp_timer_persist;
 855                         f_reset = TT_PERSIST_RST;
 856                         break;
 857                 case TT_KEEP:
 858                         t_callout = &tp->t_timers->tt_keep;
 859                         f_callout = tcp_timer_keep;
 860                         f_reset = TT_KEEP_RST;
 861                         break;
 862                 case TT_2MSL:
 863                         t_callout = &tp->t_timers->tt_2msl;
 864                         f_callout = tcp_timer_2msl;
 865                         f_reset = TT_2MSL_RST;
 866                         break;
 867                 default:
 868                         if (tp->t_fb->tfb_tcp_timer_activate) {
 869                                 tp->t_fb->tfb_tcp_timer_activate(tp, timer_type, delta);
 870                                 return;
 871                         }
 872                         panic("tp %p bad timer_type %#x", tp, timer_type);
 873                 }
 874         if (delta == 0) {
 875                 if ((tp->t_timers->tt_flags & timer_type) &&
 876                     (callout_stop(t_callout) > 0) &&
 877                     (tp->t_timers->tt_flags & f_reset)) {
 878                         tp->t_timers->tt_flags &= ~(timer_type | f_reset);
 879                 }
 880         } else {
 881                 if ((tp->t_timers->tt_flags & timer_type) == 0) {
 882                         tp->t_timers->tt_flags |= (timer_type | f_reset);
 883                         callout_reset_on(t_callout, delta, f_callout, tp, cpu);
 884                 } else {
 885                         /* Reset already running callout on the same CPU. */
 886                         if (!callout_reset(t_callout, delta, f_callout, tp)) {
 887                                 /*
 888                                  * Callout not cancelled, consider it as not
 889                                  * properly restarted. */
 890                                 tp->t_timers->tt_flags &= ~f_reset;
 891                         }
 892                 }
 893         }
 894 }
 895
 896 int
 897 tcp_timer_active(struct tcpcb *tp, uint32_t 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                         if (tp->t_fb->tfb_tcp_timer_active) {
 919                                 return(tp->t_fb->tfb_tcp_timer_active(tp, timer_type));
 920                         }
 921                         panic("tp %p bad timer_type %#x", tp, timer_type);
 922                 }
 923         return callout_active(t_callout);
 924 }
 925
 926 void
 927 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
 928 {
 929         struct callout *t_callout;
 930         uint32_t f_reset;
 931
 932         tp->t_timers->tt_flags |= TT_STOPPED;
 933
 934         switch (timer_type) {
 935                 case TT_DELACK:
 936                         t_callout = &tp->t_timers->tt_delack;
 937                         f_reset = TT_DELACK_RST;
 938                         break;
 939                 case TT_REXMT:
 940                         t_callout = &tp->t_timers->tt_rexmt;
 941                         f_reset = TT_REXMT_RST;
 942                         break;
 943                 case TT_PERSIST:
 944                         t_callout = &tp->t_timers->tt_persist;
 945                         f_reset = TT_PERSIST_RST;
 946                         break;
 947                 case TT_KEEP:
 948                         t_callout = &tp->t_timers->tt_keep;
 949                         f_reset = TT_KEEP_RST;
 950                         break;
 951                 case TT_2MSL:
 952                         t_callout = &tp->t_timers->tt_2msl;
 953                         f_reset = TT_2MSL_RST;
 954                         break;
 955                 default:
 956                         if (tp->t_fb->tfb_tcp_timer_stop) {
 957                                 /*
 958                                  * XXXrrs we need to look at this with the
 959                                  * stop case below (flags).
 960                                  */
 961                                 tp->t_fb->tfb_tcp_timer_stop(tp, timer_type);
 962                                 return;
 963                         }
 964                         panic("tp %p bad timer_type %#x", tp, timer_type);
 965                 }
 966
 967         if (tp->t_timers->tt_flags & timer_type) {
 968                 if (callout_async_drain(t_callout, tcp_timer_discard) == 0) {
 969                         /*
 970                          * Can't stop the callout, defer tcpcb actual deletion
 971                          * to the last one. We do this using the async drain
 972                          * function and incrementing the count in
 973                          */
 974                         tp->t_timers->tt_draincnt++;
 975                 }
 976         }
 977 }
 978
 979 #define ticks_to_msecs(t)       (1000*(t) / hz)
 980
 981 void
 982 tcp_timer_to_xtimer(struct tcpcb *tp, struct tcp_timer *timer,
 983     struct xtcp_timer *xtimer)
 984 {
 985         sbintime_t now;
 986
 987         bzero(xtimer, sizeof(*xtimer));
 988         if (timer == NULL)
 989                 return;
 990         now = getsbinuptime();
 991         if (callout_active(&timer->tt_delack))
 992                 xtimer->tt_delack = (timer->tt_delack.c_time - now) / SBT_1MS;
 993         if (callout_active(&timer->tt_rexmt))
 994                 xtimer->tt_rexmt = (timer->tt_rexmt.c_time - now) / SBT_1MS;
 995         if (callout_active(&timer->tt_persist))
 996                 xtimer->tt_persist = (timer->tt_persist.c_time - now) / SBT_1MS;
 997         if (callout_active(&timer->tt_keep))
 998                 xtimer->tt_keep = (timer->tt_keep.c_time - now) / SBT_1MS;
 999         if (callout_active(&timer->tt_2msl))
1000                 xtimer->tt_2msl = (timer->tt_2msl.c_time - now) / SBT_1MS;
1001         xtimer->t_rcvtime = ticks_to_msecs(ticks - tp->t_rcvtime);
1002 }