The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/tcp_timer.c

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    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: head/sys/netinet/tcp_timer.c 268027 2014-06-30 04:26:29Z adrian $");
   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 #ifdef  RSS
  131 static int      per_cpu_timers = 1;
  132 #else
  133 static int      per_cpu_timers = 0;
  134 #endif
  135 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
  136     &per_cpu_timers , 0, "run tcp timers on all cpus");
  137 
  138 #if 0
  139 #define INP_CPU(inp)    (per_cpu_timers ? (!CPU_ABSENT(((inp)->inp_flowid % (mp_maxid+1))) ? \
  140                 ((inp)->inp_flowid % (mp_maxid+1)) : curcpu) : 0)
  141 #endif
  142 
  143 /*
  144  * Map the given inp to a CPU id.
  145  *
  146  * This queries RSS if it's compiled in, else it defaults to the current
  147  * CPU ID.
  148  */
  149 static inline int
  150 inp_to_cpuid(struct inpcb *inp)
  151 {
  152         u_int cpuid;
  153 
  154 #ifdef  RSS
  155         if (per_cpu_timers) {
  156                 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
  157                 if (cpuid == NETISR_CPUID_NONE)
  158                         return (curcpu);        /* XXX */
  159                 else
  160                         return (cpuid);
  161         }
  162 #else
  163         /* Legacy, pre-RSS behaviour */
  164         if (per_cpu_timers) {
  165                 /*
  166                  * We don't have a flowid -> cpuid mapping, so cheat and
  167                  * just map unknown cpuids to curcpu.  Not the best, but
  168                  * apparently better than defaulting to swi 0.
  169                  */
  170                 cpuid = inp->inp_flowid % (mp_maxid + 1);
  171                 if (! CPU_ABSENT(cpuid))
  172                         return (cpuid);
  173                 return (curcpu);
  174         }
  175 #endif
  176         /* Default for RSS and non-RSS - cpuid 0 */
  177         else {
  178                 return (0);
  179         }
  180 }
  181 
  182 /*
  183  * Tcp protocol timeout routine called every 500 ms.
  184  * Updates timestamps used for TCP
  185  * causes finite state machine actions if timers expire.
  186  */
  187 void
  188 tcp_slowtimo(void)
  189 {
  190         VNET_ITERATOR_DECL(vnet_iter);
  191 
  192         VNET_LIST_RLOCK_NOSLEEP();
  193         VNET_FOREACH(vnet_iter) {
  194                 CURVNET_SET(vnet_iter);
  195                 tcp_tw_2msl_scan();
  196                 CURVNET_RESTORE();
  197         }
  198         VNET_LIST_RUNLOCK_NOSLEEP();
  199 }
  200 
  201 int     tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] =
  202     { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 };
  203 
  204 int     tcp_backoff[TCP_MAXRXTSHIFT + 1] =
  205     { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
  206 
  207 static int tcp_totbackoff = 2559;       /* sum of tcp_backoff[] */
  208 
  209 static int tcp_timer_race;
  210 SYSCTL_INT(_net_inet_tcp, OID_AUTO, timer_race, CTLFLAG_RD, &tcp_timer_race,
  211     0, "Count of t_inpcb races on tcp_discardcb");
  212 
  213 /*
  214  * TCP timer processing.
  215  */
  216 
  217 void
  218 tcp_timer_delack(void *xtp)
  219 {
  220         struct tcpcb *tp = xtp;
  221         struct inpcb *inp;
  222         CURVNET_SET(tp->t_vnet);
  223 
  224         inp = tp->t_inpcb;
  225         /*
  226          * XXXRW: While this assert is in fact correct, bugs in the tcpcb
  227          * tear-down mean we need it as a work-around for races between
  228          * timers and tcp_discardcb().
  229          *
  230          * KASSERT(inp != NULL, ("tcp_timer_delack: inp == NULL"));
  231          */
  232         if (inp == NULL) {
  233                 tcp_timer_race++;
  234                 CURVNET_RESTORE();
  235                 return;
  236         }
  237         INP_WLOCK(inp);
  238         if (callout_pending(&tp->t_timers->tt_delack) ||
  239             !callout_active(&tp->t_timers->tt_delack)) {
  240                 INP_WUNLOCK(inp);
  241                 CURVNET_RESTORE();
  242                 return;
  243         }
  244         callout_deactivate(&tp->t_timers->tt_delack);
  245         if ((inp->inp_flags & INP_DROPPED) != 0) {
  246                 INP_WUNLOCK(inp);
  247                 CURVNET_RESTORE();
  248                 return;
  249         }
  250 
  251         tp->t_flags |= TF_ACKNOW;
  252         TCPSTAT_INC(tcps_delack);
  253         (void) tcp_output(tp);
  254         INP_WUNLOCK(inp);
  255         CURVNET_RESTORE();
  256 }
  257 
  258 void
  259 tcp_timer_2msl(void *xtp)
  260 {
  261         struct tcpcb *tp = xtp;
  262         struct inpcb *inp;
  263         CURVNET_SET(tp->t_vnet);
  264 #ifdef TCPDEBUG
  265         int ostate;
  266 
  267         ostate = tp->t_state;
  268 #endif
  269         /*
  270          * XXXRW: Does this actually happen?
  271          */
  272         INP_INFO_WLOCK(&V_tcbinfo);
  273         inp = tp->t_inpcb;
  274         /*
  275          * XXXRW: While this assert is in fact correct, bugs in the tcpcb
  276          * tear-down mean we need it as a work-around for races between
  277          * timers and tcp_discardcb().
  278          *
  279          * KASSERT(inp != NULL, ("tcp_timer_2msl: inp == NULL"));
  280          */
  281         if (inp == NULL) {
  282                 tcp_timer_race++;
  283                 INP_INFO_WUNLOCK(&V_tcbinfo);
  284                 CURVNET_RESTORE();
  285                 return;
  286         }
  287         INP_WLOCK(inp);
  288         tcp_free_sackholes(tp);
  289         if (callout_pending(&tp->t_timers->tt_2msl) ||
  290             !callout_active(&tp->t_timers->tt_2msl)) {
  291                 INP_WUNLOCK(tp->t_inpcb);
  292                 INP_INFO_WUNLOCK(&V_tcbinfo);
  293                 CURVNET_RESTORE();
  294                 return;
  295         }
  296         callout_deactivate(&tp->t_timers->tt_2msl);
  297         if ((inp->inp_flags & INP_DROPPED) != 0) {
  298                 INP_WUNLOCK(inp);
  299                 INP_INFO_WUNLOCK(&V_tcbinfo);
  300                 CURVNET_RESTORE();
  301                 return;
  302         }
  303         /*
  304          * 2 MSL timeout in shutdown went off.  If we're closed but
  305          * still waiting for peer to close and connection has been idle
  306          * too long, or if 2MSL time is up from TIME_WAIT, delete connection
  307          * control block.  Otherwise, check again in a bit.
  308          *
  309          * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed, 
  310          * there's no point in hanging onto FIN_WAIT_2 socket. Just close it. 
  311          * Ignore fact that there were recent incoming segments.
  312          */
  313         if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
  314             tp->t_inpcb && tp->t_inpcb->inp_socket && 
  315             (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
  316                 TCPSTAT_INC(tcps_finwait2_drops);
  317                 tp = tcp_close(tp);             
  318         } else {
  319                 if (tp->t_state != TCPS_TIME_WAIT &&
  320                    ticks - tp->t_rcvtime <= TP_MAXIDLE(tp))
  321                        callout_reset_on(&tp->t_timers->tt_2msl,
  322                            TP_KEEPINTVL(tp), tcp_timer_2msl, tp,
  323                            inp_to_cpuid(inp));
  324                else
  325                        tp = tcp_close(tp);
  326        }
  327 
  328 #ifdef TCPDEBUG
  329         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
  330                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
  331                           PRU_SLOWTIMO);
  332 #endif
  333         if (tp != NULL)
  334                 INP_WUNLOCK(inp);
  335         INP_INFO_WUNLOCK(&V_tcbinfo);
  336         CURVNET_RESTORE();
  337 }
  338 
  339 void
  340 tcp_timer_keep(void *xtp)
  341 {
  342         struct tcpcb *tp = xtp;
  343         struct tcptemp *t_template;
  344         struct inpcb *inp;
  345         CURVNET_SET(tp->t_vnet);
  346 #ifdef TCPDEBUG
  347         int ostate;
  348 
  349         ostate = tp->t_state;
  350 #endif
  351         INP_INFO_WLOCK(&V_tcbinfo);
  352         inp = tp->t_inpcb;
  353         /*
  354          * XXXRW: While this assert is in fact correct, bugs in the tcpcb
  355          * tear-down mean we need it as a work-around for races between
  356          * timers and tcp_discardcb().
  357          *
  358          * KASSERT(inp != NULL, ("tcp_timer_keep: inp == NULL"));
  359          */
  360         if (inp == NULL) {
  361                 tcp_timer_race++;
  362                 INP_INFO_WUNLOCK(&V_tcbinfo);
  363                 CURVNET_RESTORE();
  364                 return;
  365         }
  366         INP_WLOCK(inp);
  367         if (callout_pending(&tp->t_timers->tt_keep) ||
  368             !callout_active(&tp->t_timers->tt_keep)) {
  369                 INP_WUNLOCK(inp);
  370                 INP_INFO_WUNLOCK(&V_tcbinfo);
  371                 CURVNET_RESTORE();
  372                 return;
  373         }
  374         callout_deactivate(&tp->t_timers->tt_keep);
  375         if ((inp->inp_flags & INP_DROPPED) != 0) {
  376                 INP_WUNLOCK(inp);
  377                 INP_INFO_WUNLOCK(&V_tcbinfo);
  378                 CURVNET_RESTORE();
  379                 return;
  380         }
  381         /*
  382          * Keep-alive timer went off; send something
  383          * or drop connection if idle for too long.
  384          */
  385         TCPSTAT_INC(tcps_keeptimeo);
  386         if (tp->t_state < TCPS_ESTABLISHED)
  387                 goto dropit;
  388         if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) &&
  389             tp->t_state <= TCPS_CLOSING) {
  390                 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
  391                         goto dropit;
  392                 /*
  393                  * Send a packet designed to force a response
  394                  * if the peer is up and reachable:
  395                  * either an ACK if the connection is still alive,
  396                  * or an RST if the peer has closed the connection
  397                  * due to timeout or reboot.
  398                  * Using sequence number tp->snd_una-1
  399                  * causes the transmitted zero-length segment
  400                  * to lie outside the receive window;
  401                  * by the protocol spec, this requires the
  402                  * correspondent TCP to respond.
  403                  */
  404                 TCPSTAT_INC(tcps_keepprobe);
  405                 t_template = tcpip_maketemplate(inp);
  406                 if (t_template) {
  407                         tcp_respond(tp, t_template->tt_ipgen,
  408                                     &t_template->tt_t, (struct mbuf *)NULL,
  409                                     tp->rcv_nxt, tp->snd_una - 1, 0);
  410                         free(t_template, M_TEMP);
  411                 }
  412                 callout_reset_on(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
  413                     tcp_timer_keep, tp, inp_to_cpuid(inp));
  414         } else
  415                 callout_reset_on(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
  416                     tcp_timer_keep, tp, inp_to_cpuid(inp));
  417 
  418 #ifdef TCPDEBUG
  419         if (inp->inp_socket->so_options & SO_DEBUG)
  420                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
  421                           PRU_SLOWTIMO);
  422 #endif
  423         INP_WUNLOCK(inp);
  424         INP_INFO_WUNLOCK(&V_tcbinfo);
  425         CURVNET_RESTORE();
  426         return;
  427 
  428 dropit:
  429         TCPSTAT_INC(tcps_keepdrops);
  430         tp = tcp_drop(tp, ETIMEDOUT);
  431 
  432 #ifdef TCPDEBUG
  433         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
  434                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
  435                           PRU_SLOWTIMO);
  436 #endif
  437         if (tp != NULL)
  438                 INP_WUNLOCK(tp->t_inpcb);
  439         INP_INFO_WUNLOCK(&V_tcbinfo);
  440         CURVNET_RESTORE();
  441 }
  442 
  443 void
  444 tcp_timer_persist(void *xtp)
  445 {
  446         struct tcpcb *tp = xtp;
  447         struct inpcb *inp;
  448         CURVNET_SET(tp->t_vnet);
  449 #ifdef TCPDEBUG
  450         int ostate;
  451 
  452         ostate = tp->t_state;
  453 #endif
  454         INP_INFO_WLOCK(&V_tcbinfo);
  455         inp = tp->t_inpcb;
  456         /*
  457          * XXXRW: While this assert is in fact correct, bugs in the tcpcb
  458          * tear-down mean we need it as a work-around for races between
  459          * timers and tcp_discardcb().
  460          *
  461          * KASSERT(inp != NULL, ("tcp_timer_persist: inp == NULL"));
  462          */
  463         if (inp == NULL) {
  464                 tcp_timer_race++;
  465                 INP_INFO_WUNLOCK(&V_tcbinfo);
  466                 CURVNET_RESTORE();
  467                 return;
  468         }
  469         INP_WLOCK(inp);
  470         if (callout_pending(&tp->t_timers->tt_persist) ||
  471             !callout_active(&tp->t_timers->tt_persist)) {
  472                 INP_WUNLOCK(inp);
  473                 INP_INFO_WUNLOCK(&V_tcbinfo);
  474                 CURVNET_RESTORE();
  475                 return;
  476         }
  477         callout_deactivate(&tp->t_timers->tt_persist);
  478         if ((inp->inp_flags & INP_DROPPED) != 0) {
  479                 INP_WUNLOCK(inp);
  480                 INP_INFO_WUNLOCK(&V_tcbinfo);
  481                 CURVNET_RESTORE();
  482                 return;
  483         }
  484         /*
  485          * Persistance timer into zero window.
  486          * Force a byte to be output, if possible.
  487          */
  488         TCPSTAT_INC(tcps_persisttimeo);
  489         /*
  490          * Hack: if the peer is dead/unreachable, we do not
  491          * time out if the window is closed.  After a full
  492          * backoff, drop the connection if the idle time
  493          * (no responses to probes) reaches the maximum
  494          * backoff that we would use if retransmitting.
  495          */
  496         if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
  497             (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
  498              ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
  499                 TCPSTAT_INC(tcps_persistdrop);
  500                 tp = tcp_drop(tp, ETIMEDOUT);
  501                 goto out;
  502         }
  503         /*
  504          * If the user has closed the socket then drop a persisting
  505          * connection after a much reduced timeout.
  506          */
  507         if (tp->t_state > TCPS_CLOSE_WAIT &&
  508             (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
  509                 TCPSTAT_INC(tcps_persistdrop);
  510                 tp = tcp_drop(tp, ETIMEDOUT);
  511                 goto out;
  512         }
  513         tcp_setpersist(tp);
  514         tp->t_flags |= TF_FORCEDATA;
  515         (void) tcp_output(tp);
  516         tp->t_flags &= ~TF_FORCEDATA;
  517 
  518 out:
  519 #ifdef TCPDEBUG
  520         if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
  521                 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
  522 #endif
  523         if (tp != NULL)
  524                 INP_WUNLOCK(inp);
  525         INP_INFO_WUNLOCK(&V_tcbinfo);
  526         CURVNET_RESTORE();
  527 }
  528 
  529 void
  530 tcp_timer_rexmt(void * xtp)
  531 {
  532         struct tcpcb *tp = xtp;
  533         CURVNET_SET(tp->t_vnet);
  534         int rexmt;
  535         int headlocked;
  536         struct inpcb *inp;
  537 #ifdef TCPDEBUG
  538         int ostate;
  539 
  540         ostate = tp->t_state;
  541 #endif
  542         INP_INFO_RLOCK(&V_tcbinfo);
  543         inp = tp->t_inpcb;
  544         /*
  545          * XXXRW: While this assert is in fact correct, bugs in the tcpcb
  546          * tear-down mean we need it as a work-around for races between
  547          * timers and tcp_discardcb().
  548          *
  549          * KASSERT(inp != NULL, ("tcp_timer_rexmt: inp == NULL"));
  550          */
  551         if (inp == NULL) {
  552                 tcp_timer_race++;
  553                 INP_INFO_RUNLOCK(&V_tcbinfo);
  554                 CURVNET_RESTORE();
  555                 return;
  556         }
  557         INP_WLOCK(inp);
  558         if (callout_pending(&tp->t_timers->tt_rexmt) ||
  559             !callout_active(&tp->t_timers->tt_rexmt)) {
  560                 INP_WUNLOCK(inp);
  561                 INP_INFO_RUNLOCK(&V_tcbinfo);
  562                 CURVNET_RESTORE();
  563                 return;
  564         }
  565         callout_deactivate(&tp->t_timers->tt_rexmt);
  566         if ((inp->inp_flags & INP_DROPPED) != 0) {
  567                 INP_WUNLOCK(inp);
  568                 INP_INFO_RUNLOCK(&V_tcbinfo);
  569                 CURVNET_RESTORE();
  570                 return;
  571         }
  572         tcp_free_sackholes(tp);
  573         /*
  574          * Retransmission timer went off.  Message has not
  575          * been acked within retransmit interval.  Back off
  576          * to a longer retransmit interval and retransmit one segment.
  577          */
  578         if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
  579                 tp->t_rxtshift = TCP_MAXRXTSHIFT;
  580                 TCPSTAT_INC(tcps_timeoutdrop);
  581                 in_pcbref(inp);
  582                 INP_INFO_RUNLOCK(&V_tcbinfo);
  583                 INP_WUNLOCK(inp);
  584                 INP_INFO_WLOCK(&V_tcbinfo);
  585                 INP_WLOCK(inp);
  586                 if (in_pcbrele_wlocked(inp)) {
  587                         INP_INFO_WUNLOCK(&V_tcbinfo);
  588                         CURVNET_RESTORE();
  589                         return;
  590                 }
  591                 if (inp->inp_flags & INP_DROPPED) {
  592                         INP_WUNLOCK(inp);
  593                         INP_INFO_WUNLOCK(&V_tcbinfo);
  594                         CURVNET_RESTORE();
  595                         return;
  596                 }
  597 
  598                 tp = tcp_drop(tp, tp->t_softerror ?
  599                               tp->t_softerror : ETIMEDOUT);
  600                 headlocked = 1;
  601                 goto out;
  602         }
  603         INP_INFO_RUNLOCK(&V_tcbinfo);
  604         headlocked = 0;
  605         if (tp->t_state == TCPS_SYN_SENT) {
  606                 /*
  607                  * If the SYN was retransmitted, indicate CWND to be
  608                  * limited to 1 segment in cc_conn_init().
  609                  */
  610                 tp->snd_cwnd = 1;
  611         } else if (tp->t_rxtshift == 1) {
  612                 /*
  613                  * first retransmit; record ssthresh and cwnd so they can
  614                  * be recovered if this turns out to be a "bad" retransmit.
  615                  * A retransmit is considered "bad" if an ACK for this
  616                  * segment is received within RTT/2 interval; the assumption
  617                  * here is that the ACK was already in flight.  See
  618                  * "On Estimating End-to-End Network Path Properties" by
  619                  * Allman and Paxson for more details.
  620                  */
  621                 tp->snd_cwnd_prev = tp->snd_cwnd;
  622                 tp->snd_ssthresh_prev = tp->snd_ssthresh;
  623                 tp->snd_recover_prev = tp->snd_recover;
  624                 if (IN_FASTRECOVERY(tp->t_flags))
  625                         tp->t_flags |= TF_WASFRECOVERY;
  626                 else
  627                         tp->t_flags &= ~TF_WASFRECOVERY;
  628                 if (IN_CONGRECOVERY(tp->t_flags))
  629                         tp->t_flags |= TF_WASCRECOVERY;
  630                 else
  631                         tp->t_flags &= ~TF_WASCRECOVERY;
  632                 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
  633                 tp->t_flags |= TF_PREVVALID;
  634         } else
  635                 tp->t_flags &= ~TF_PREVVALID;
  636         TCPSTAT_INC(tcps_rexmttimeo);
  637         if (tp->t_state == TCPS_SYN_SENT)
  638                 rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift];
  639         else
  640                 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
  641         TCPT_RANGESET(tp->t_rxtcur, rexmt,
  642                       tp->t_rttmin, TCPTV_REXMTMAX);
  643         /*
  644          * Disable RFC1323 and SACK if we haven't got any response to
  645          * our third SYN to work-around some broken terminal servers
  646          * (most of which have hopefully been retired) that have bad VJ
  647          * header compression code which trashes TCP segments containing
  648          * unknown-to-them TCP options.
  649          */
  650         if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
  651             (tp->t_rxtshift == 3))
  652                 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
  653         /*
  654          * If we backed off this far, our srtt estimate is probably bogus.
  655          * Clobber it so we'll take the next rtt measurement as our srtt;
  656          * move the current srtt into rttvar to keep the current
  657          * retransmit times until then.
  658          */
  659         if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
  660 #ifdef INET6
  661                 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
  662                         in6_losing(tp->t_inpcb);
  663 #endif
  664                 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
  665                 tp->t_srtt = 0;
  666         }
  667         tp->snd_nxt = tp->snd_una;
  668         tp->snd_recover = tp->snd_max;
  669         /*
  670          * Force a segment to be sent.
  671          */
  672         tp->t_flags |= TF_ACKNOW;
  673         /*
  674          * If timing a segment in this window, stop the timer.
  675          */
  676         tp->t_rtttime = 0;
  677 
  678         cc_cong_signal(tp, NULL, CC_RTO);
  679 
  680         (void) tcp_output(tp);
  681 
  682 out:
  683 #ifdef TCPDEBUG
  684         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
  685                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
  686                           PRU_SLOWTIMO);
  687 #endif
  688         if (tp != NULL)
  689                 INP_WUNLOCK(inp);
  690         if (headlocked)
  691                 INP_INFO_WUNLOCK(&V_tcbinfo);
  692         CURVNET_RESTORE();
  693 }
  694 
  695 void
  696 tcp_timer_activate(struct tcpcb *tp, int timer_type, u_int delta)
  697 {
  698         struct callout *t_callout;
  699         void *f_callout;
  700         struct inpcb *inp = tp->t_inpcb;
  701         int cpu = inp_to_cpuid(inp);
  702 
  703 #ifdef TCP_OFFLOAD
  704         if (tp->t_flags & TF_TOE)
  705                 return;
  706 #endif
  707 
  708         switch (timer_type) {
  709                 case TT_DELACK:
  710                         t_callout = &tp->t_timers->tt_delack;
  711                         f_callout = tcp_timer_delack;
  712                         break;
  713                 case TT_REXMT:
  714                         t_callout = &tp->t_timers->tt_rexmt;
  715                         f_callout = tcp_timer_rexmt;
  716                         break;
  717                 case TT_PERSIST:
  718                         t_callout = &tp->t_timers->tt_persist;
  719                         f_callout = tcp_timer_persist;
  720                         break;
  721                 case TT_KEEP:
  722                         t_callout = &tp->t_timers->tt_keep;
  723                         f_callout = tcp_timer_keep;
  724                         break;
  725                 case TT_2MSL:
  726                         t_callout = &tp->t_timers->tt_2msl;
  727                         f_callout = tcp_timer_2msl;
  728                         break;
  729                 default:
  730                         panic("bad timer_type");
  731                 }
  732         if (delta == 0) {
  733                 callout_stop(t_callout);
  734         } else {
  735                 callout_reset_on(t_callout, delta, f_callout, tp, cpu);
  736         }
  737 }
  738 
  739 int
  740 tcp_timer_active(struct tcpcb *tp, int timer_type)
  741 {
  742         struct callout *t_callout;
  743 
  744         switch (timer_type) {
  745                 case TT_DELACK:
  746                         t_callout = &tp->t_timers->tt_delack;
  747                         break;
  748                 case TT_REXMT:
  749                         t_callout = &tp->t_timers->tt_rexmt;
  750                         break;
  751                 case TT_PERSIST:
  752                         t_callout = &tp->t_timers->tt_persist;
  753                         break;
  754                 case TT_KEEP:
  755                         t_callout = &tp->t_timers->tt_keep;
  756                         break;
  757                 case TT_2MSL:
  758                         t_callout = &tp->t_timers->tt_2msl;
  759                         break;
  760                 default:
  761                         panic("bad timer_type");
  762                 }
  763         return callout_active(t_callout);
  764 }
  765 
  766 #define ticks_to_msecs(t)       (1000*(t) / hz)
  767 
  768 void
  769 tcp_timer_to_xtimer(struct tcpcb *tp, struct tcp_timer *timer,
  770     struct xtcp_timer *xtimer)
  771 {
  772         sbintime_t now;
  773 
  774         bzero(xtimer, sizeof(*xtimer));
  775         if (timer == NULL)
  776                 return;
  777         now = getsbinuptime();
  778         if (callout_active(&timer->tt_delack))
  779                 xtimer->tt_delack = (timer->tt_delack.c_time - now) / SBT_1MS;
  780         if (callout_active(&timer->tt_rexmt))
  781                 xtimer->tt_rexmt = (timer->tt_rexmt.c_time - now) / SBT_1MS;
  782         if (callout_active(&timer->tt_persist))
  783                 xtimer->tt_persist = (timer->tt_persist.c_time - now) / SBT_1MS;
  784         if (callout_active(&timer->tt_keep))
  785                 xtimer->tt_keep = (timer->tt_keep.c_time - now) / SBT_1MS;
  786         if (callout_active(&timer->tt_2msl))
  787                 xtimer->tt_2msl = (timer->tt_2msl.c_time - now) / SBT_1MS;
  788         xtimer->t_rcvtime = ticks_to_msecs(ticks - tp->t_rcvtime);
  789 }

Cache object: e4d014ddac5215416e54c3e00c1e37b9


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