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freebsd-dev/sys/netinet/tcp_timer.c
Michael Tuexen 0999766ddf Add sysctl variable net.inet.tcp.rexmit_initial for setting RTO.Initial 
used by TCP.

Reviewed by:		rrs@, 0mp@
Sponsored by:		Netflix, Inc.
Differential Revision:	https://reviews.freebsd.org/D19355
2019-03-23 21:36:59 +00:00

1067 lines
30 KiB
C
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/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_inet.h"
#include "opt_inet6.h"
#include "opt_tcpdebug.h"
#include "opt_rss.h"
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
#include <sys/protosw.h>
#include <sys/smp.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <net/if.h>
#include <net/route.h>
#include <net/rss_config.h>
#include <net/vnet.h>
#include <net/netisr.h>
#include <netinet/in.h>
#include <netinet/in_kdtrace.h>
#include <netinet/in_pcb.h>
#include <netinet/in_rss.h>
#include <netinet/in_systm.h>
#ifdef INET6
#include <netinet6/in6_pcb.h>
#endif
#include <netinet/ip_var.h>
#include <netinet/tcp.h>
#include <netinet/tcp_fsm.h>
#include <netinet/tcp_log_buf.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <netinet/tcp_seq.h>
#include <netinet/cc/cc.h>
#ifdef INET6
#include <netinet6/tcp6_var.h>
#endif
#include <netinet/tcpip.h>
#ifdef TCPDEBUG
#include <netinet/tcp_debug.h>
#endif
int tcp_persmin;
SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmin, CTLTYPE_INT|CTLFLAG_RW,
&tcp_persmin, 0, sysctl_msec_to_ticks, "I", "minimum persistence interval");
int tcp_persmax;
SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmax, CTLTYPE_INT|CTLFLAG_RW,
&tcp_persmax, 0, sysctl_msec_to_ticks, "I", "maximum persistence interval");
int tcp_keepinit;
SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
&tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "time to establish connection");
int tcp_keepidle;
SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
&tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "time before keepalive probes begin");
int tcp_keepintvl;
SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
&tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "time between keepalive probes");
int tcp_delacktime;
SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW,
&tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
"Time before a delayed ACK is sent");
int tcp_msl;
SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
&tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
int tcp_rexmit_initial;
SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_initial, CTLTYPE_INT|CTLFLAG_RW,
&tcp_rexmit_initial, 0, sysctl_msec_to_ticks, "I",
"Initial Retransmission Timeout");
int tcp_rexmit_min;
SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
&tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
"Minimum Retransmission Timeout");
int tcp_rexmit_slop;
SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
&tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
"Retransmission Timer Slop");
int tcp_always_keepalive = 1;
SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW,
&tcp_always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections");
int tcp_fast_finwait2_recycle = 0;
SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
&tcp_fast_finwait2_recycle, 0,
"Recycle closed FIN_WAIT_2 connections faster");
int tcp_finwait2_timeout;
SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW,
&tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout");
int tcp_keepcnt = TCPTV_KEEPCNT;
SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
"Number of keepalive probes to send");
/* max idle probes */
int tcp_maxpersistidle;
int tcp_rexmit_drop_options = 0;
SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
&tcp_rexmit_drop_options, 0,
"Drop TCP options from 3rd and later retransmitted SYN");
VNET_DEFINE(int, tcp_pmtud_blackhole_detect);
SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection,
CTLFLAG_RW|CTLFLAG_VNET,
&VNET_NAME(tcp_pmtud_blackhole_detect), 0,
"Path MTU Discovery Black Hole Detection Enabled");
#ifdef INET
VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200;
SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss,
CTLFLAG_RW|CTLFLAG_VNET,
&VNET_NAME(tcp_pmtud_blackhole_mss), 0,
"Path MTU Discovery Black Hole Detection lowered MSS");
#endif
#ifdef INET6
VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220;
SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss,
CTLFLAG_RW|CTLFLAG_VNET,
&VNET_NAME(tcp_v6pmtud_blackhole_mss), 0,
"Path MTU Discovery IPv6 Black Hole Detection lowered MSS");
#endif
#ifdef RSS
static int per_cpu_timers = 1;
#else
static int per_cpu_timers = 0;
#endif
SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
&per_cpu_timers , 0, "run tcp timers on all cpus");
/*
* Map the given inp to a CPU id.
*
* This queries RSS if it's compiled in, else it defaults to the current
* CPU ID.
*/
inline int
inp_to_cpuid(struct inpcb *inp)
{
u_int cpuid;
#ifdef RSS
if (per_cpu_timers) {
cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
if (cpuid == NETISR_CPUID_NONE)
return (curcpu); /* XXX */
else
return (cpuid);
}
#else
/* Legacy, pre-RSS behaviour */
if (per_cpu_timers) {
/*
* We don't have a flowid -> cpuid mapping, so cheat and
* just map unknown cpuids to curcpu. Not the best, but
* apparently better than defaulting to swi 0.
*/
cpuid = inp->inp_flowid % (mp_maxid + 1);
if (! CPU_ABSENT(cpuid))
return (cpuid);
return (curcpu);
}
#endif
/* Default for RSS and non-RSS - cpuid 0 */
else {
return (0);
}
}
/*
* Tcp protocol timeout routine called every 500 ms.
* Updates timestamps used for TCP
* causes finite state machine actions if timers expire.
*/
void
tcp_slowtimo(void)
{
VNET_ITERATOR_DECL(vnet_iter);
VNET_LIST_RLOCK_NOSLEEP();
VNET_FOREACH(vnet_iter) {
CURVNET_SET(vnet_iter);
(void) tcp_tw_2msl_scan(0);
CURVNET_RESTORE();
}
VNET_LIST_RUNLOCK_NOSLEEP();
}
int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
{ 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */
/*
* TCP timer processing.
*/
void
tcp_timer_delack(void *xtp)
{
struct tcpcb *tp = xtp;
struct inpcb *inp;
CURVNET_SET(tp->t_vnet);
inp = tp->t_inpcb;
KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
INP_WLOCK(inp);
if (callout_pending(&tp->t_timers->tt_delack) ||
!callout_active(&tp->t_timers->tt_delack)) {
INP_WUNLOCK(inp);
CURVNET_RESTORE();
return;
}
callout_deactivate(&tp->t_timers->tt_delack);
if ((inp->inp_flags & INP_DROPPED) != 0) {
INP_WUNLOCK(inp);
CURVNET_RESTORE();
return;
}
tp->t_flags |= TF_ACKNOW;
TCPSTAT_INC(tcps_delack);
(void) tp->t_fb->tfb_tcp_output(tp);
INP_WUNLOCK(inp);
CURVNET_RESTORE();
}
void
tcp_inpinfo_lock_del(struct inpcb *inp, struct tcpcb *tp)
{
if (inp && tp != NULL)
INP_WUNLOCK(inp);
}
void
tcp_timer_2msl(void *xtp)
{
struct tcpcb *tp = xtp;
struct inpcb *inp;
struct epoch_tracker et;
CURVNET_SET(tp->t_vnet);
#ifdef TCPDEBUG
int ostate;
ostate = tp->t_state;
#endif
inp = tp->t_inpcb;
KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
INP_WLOCK(inp);
tcp_free_sackholes(tp);
if (callout_pending(&tp->t_timers->tt_2msl) ||
!callout_active(&tp->t_timers->tt_2msl)) {
INP_WUNLOCK(tp->t_inpcb);
CURVNET_RESTORE();
return;
}
callout_deactivate(&tp->t_timers->tt_2msl);
if ((inp->inp_flags & INP_DROPPED) != 0) {
INP_WUNLOCK(inp);
CURVNET_RESTORE();
return;
}
KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
("%s: tp %p tcpcb can't be stopped here", __func__, tp));
/*
* 2 MSL timeout in shutdown went off. If we're closed but
* still waiting for peer to close and connection has been idle
* too long delete connection control block. Otherwise, check
* again in a bit.
*
* If in TIME_WAIT state just ignore as this timeout is handled in
* tcp_tw_2msl_scan().
*
* If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
* there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
* Ignore fact that there were recent incoming segments.
*/
if ((inp->inp_flags & INP_TIMEWAIT) != 0) {
INP_WUNLOCK(inp);
CURVNET_RESTORE();
return;
}
if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
tp->t_inpcb && tp->t_inpcb->inp_socket &&
(tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
TCPSTAT_INC(tcps_finwait2_drops);
if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
tcp_inpinfo_lock_del(inp, tp);
goto out;
}
INP_INFO_RLOCK_ET(&V_tcbinfo, et);
tp = tcp_close(tp);
INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
tcp_inpinfo_lock_del(inp, tp);
goto out;
} else {
if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) {
callout_reset(&tp->t_timers->tt_2msl,
TP_KEEPINTVL(tp), tcp_timer_2msl, tp);
} else {
if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
tcp_inpinfo_lock_del(inp, tp);
goto out;
}
INP_INFO_RLOCK_ET(&V_tcbinfo, et);
tp = tcp_close(tp);
INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
tcp_inpinfo_lock_del(inp, tp);
goto out;
}
}
#ifdef TCPDEBUG
if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
PRU_SLOWTIMO);
#endif
TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
if (tp != NULL)
INP_WUNLOCK(inp);
out:
CURVNET_RESTORE();
}
void
tcp_timer_keep(void *xtp)
{
struct tcpcb *tp = xtp;
struct tcptemp *t_template;
struct inpcb *inp;
struct epoch_tracker et;
CURVNET_SET(tp->t_vnet);
#ifdef TCPDEBUG
int ostate;
ostate = tp->t_state;
#endif
inp = tp->t_inpcb;
KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
INP_WLOCK(inp);
if (callout_pending(&tp->t_timers->tt_keep) ||
!callout_active(&tp->t_timers->tt_keep)) {
INP_WUNLOCK(inp);
CURVNET_RESTORE();
return;
}
callout_deactivate(&tp->t_timers->tt_keep);
if ((inp->inp_flags & INP_DROPPED) != 0) {
INP_WUNLOCK(inp);
CURVNET_RESTORE();
return;
}
KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
("%s: tp %p tcpcb can't be stopped here", __func__, tp));
/*
* Because we don't regularly reset the keepalive callout in
* the ESTABLISHED state, it may be that we don't actually need
* to send a keepalive yet. If that occurs, schedule another
* call for the next time the keepalive timer might expire.
*/
if (TCPS_HAVEESTABLISHED(tp->t_state)) {
u_int idletime;
idletime = ticks - tp->t_rcvtime;
if (idletime < TP_KEEPIDLE(tp)) {
callout_reset(&tp->t_timers->tt_keep,
TP_KEEPIDLE(tp) - idletime, tcp_timer_keep, tp);
INP_WUNLOCK(inp);
CURVNET_RESTORE();
return;
}
}
/*
* Keep-alive timer went off; send something
* or drop connection if idle for too long.
*/
TCPSTAT_INC(tcps_keeptimeo);
if (tp->t_state < TCPS_ESTABLISHED)
goto dropit;
if ((tcp_always_keepalive ||
inp->inp_socket->so_options & SO_KEEPALIVE) &&
tp->t_state <= TCPS_CLOSING) {
if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
goto dropit;
/*
* Send a packet designed to force a response
* if the peer is up and reachable:
* either an ACK if the connection is still alive,
* or an RST if the peer has closed the connection
* due to timeout or reboot.
* Using sequence number tp->snd_una-1
* causes the transmitted zero-length segment
* to lie outside the receive window;
* by the protocol spec, this requires the
* correspondent TCP to respond.
*/
TCPSTAT_INC(tcps_keepprobe);
t_template = tcpip_maketemplate(inp);
if (t_template) {
tcp_respond(tp, t_template->tt_ipgen,
&t_template->tt_t, (struct mbuf *)NULL,
tp->rcv_nxt, tp->snd_una - 1, 0);
free(t_template, M_TEMP);
}
callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
tcp_timer_keep, tp);
} else
callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
tcp_timer_keep, tp);
#ifdef TCPDEBUG
if (inp->inp_socket->so_options & SO_DEBUG)
tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
PRU_SLOWTIMO);
#endif
TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
INP_WUNLOCK(inp);
CURVNET_RESTORE();
return;
dropit:
TCPSTAT_INC(tcps_keepdrops);
if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
tcp_inpinfo_lock_del(inp, tp);
goto out;
}
INP_INFO_RLOCK_ET(&V_tcbinfo, et);
tp = tcp_drop(tp, ETIMEDOUT);
#ifdef TCPDEBUG
if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
PRU_SLOWTIMO);
#endif
TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
tcp_inpinfo_lock_del(inp, tp);
out:
CURVNET_RESTORE();
}
void
tcp_timer_persist(void *xtp)
{
struct tcpcb *tp = xtp;
struct inpcb *inp;
struct epoch_tracker et;
CURVNET_SET(tp->t_vnet);
#ifdef TCPDEBUG
int ostate;
ostate = tp->t_state;
#endif
inp = tp->t_inpcb;
KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
INP_WLOCK(inp);
if (callout_pending(&tp->t_timers->tt_persist) ||
!callout_active(&tp->t_timers->tt_persist)) {
INP_WUNLOCK(inp);
CURVNET_RESTORE();
return;
}
callout_deactivate(&tp->t_timers->tt_persist);
if ((inp->inp_flags & INP_DROPPED) != 0) {
INP_WUNLOCK(inp);
CURVNET_RESTORE();
return;
}
KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
("%s: tp %p tcpcb can't be stopped here", __func__, tp));
/*
* Persistence timer into zero window.
* Force a byte to be output, if possible.
*/
TCPSTAT_INC(tcps_persisttimeo);
/*
* Hack: if the peer is dead/unreachable, we do not
* time out if the window is closed. After a full
* backoff, drop the connection if the idle time
* (no responses to probes) reaches the maximum
* backoff that we would use if retransmitting.
*/
if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
(ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
TCPSTAT_INC(tcps_persistdrop);
if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
tcp_inpinfo_lock_del(inp, tp);
goto out;
}
INP_INFO_RLOCK_ET(&V_tcbinfo, et);
tp = tcp_drop(tp, ETIMEDOUT);
INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
tcp_inpinfo_lock_del(inp, tp);
goto out;
}
/*
* If the user has closed the socket then drop a persisting
* connection after a much reduced timeout.
*/
if (tp->t_state > TCPS_CLOSE_WAIT &&
(ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
TCPSTAT_INC(tcps_persistdrop);
if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
tcp_inpinfo_lock_del(inp, tp);
goto out;
}
INP_INFO_RLOCK_ET(&V_tcbinfo, et);
tp = tcp_drop(tp, ETIMEDOUT);
INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
tcp_inpinfo_lock_del(inp, tp);
goto out;
}
tcp_setpersist(tp);
tp->t_flags |= TF_FORCEDATA;
(void) tp->t_fb->tfb_tcp_output(tp);
tp->t_flags &= ~TF_FORCEDATA;
#ifdef TCPDEBUG
if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
#endif
TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
INP_WUNLOCK(inp);
out:
CURVNET_RESTORE();
}
void
tcp_timer_rexmt(void * xtp)
{
struct tcpcb *tp = xtp;
CURVNET_SET(tp->t_vnet);
int rexmt;
struct inpcb *inp;
struct epoch_tracker et;
#ifdef TCPDEBUG
int ostate;
ostate = tp->t_state;
#endif
inp = tp->t_inpcb;
KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
INP_WLOCK(inp);
if (callout_pending(&tp->t_timers->tt_rexmt) ||
!callout_active(&tp->t_timers->tt_rexmt)) {
INP_WUNLOCK(inp);
CURVNET_RESTORE();
return;
}
callout_deactivate(&tp->t_timers->tt_rexmt);
if ((inp->inp_flags & INP_DROPPED) != 0) {
INP_WUNLOCK(inp);
CURVNET_RESTORE();
return;
}
KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
("%s: tp %p tcpcb can't be stopped here", __func__, tp));
tcp_free_sackholes(tp);
TCP_LOG_EVENT(tp, NULL, NULL, NULL, TCP_LOG_RTO, 0, 0, NULL, false);
if (tp->t_fb->tfb_tcp_rexmit_tmr) {
/* The stack has a timer action too. */
(*tp->t_fb->tfb_tcp_rexmit_tmr)(tp);
}
/*
* Retransmission timer went off. Message has not
* been acked within retransmit interval. Back off
* to a longer retransmit interval and retransmit one segment.
*/
if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
tp->t_rxtshift = TCP_MAXRXTSHIFT;
TCPSTAT_INC(tcps_timeoutdrop);
if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
tcp_inpinfo_lock_del(inp, tp);
goto out;
}
INP_INFO_RLOCK_ET(&V_tcbinfo, et);
tp = tcp_drop(tp, ETIMEDOUT);
INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
tcp_inpinfo_lock_del(inp, tp);
goto out;
}
if (tp->t_state == TCPS_SYN_SENT) {
/*
* If the SYN was retransmitted, indicate CWND to be
* limited to 1 segment in cc_conn_init().
*/
tp->snd_cwnd = 1;
} else if (tp->t_rxtshift == 1) {
/*
* first retransmit; record ssthresh and cwnd so they can
* be recovered if this turns out to be a "bad" retransmit.
* A retransmit is considered "bad" if an ACK for this
* segment is received within RTT/2 interval; the assumption
* here is that the ACK was already in flight. See
* "On Estimating End-to-End Network Path Properties" by
* Allman and Paxson for more details.
*/
tp->snd_cwnd_prev = tp->snd_cwnd;
tp->snd_ssthresh_prev = tp->snd_ssthresh;
tp->snd_recover_prev = tp->snd_recover;
if (IN_FASTRECOVERY(tp->t_flags))
tp->t_flags |= TF_WASFRECOVERY;
else
tp->t_flags &= ~TF_WASFRECOVERY;
if (IN_CONGRECOVERY(tp->t_flags))
tp->t_flags |= TF_WASCRECOVERY;
else
tp->t_flags &= ~TF_WASCRECOVERY;
if ((tp->t_flags & TF_RCVD_TSTMP) == 0)
tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
/* In the event that we've negotiated timestamps
* badrxtwin will be set to the value that we set
* the retransmitted packet's to_tsval to by tcp_output
*/
tp->t_flags |= TF_PREVVALID;
} else
tp->t_flags &= ~TF_PREVVALID;
TCPSTAT_INC(tcps_rexmttimeo);
if ((tp->t_state == TCPS_SYN_SENT) ||
(tp->t_state == TCPS_SYN_RECEIVED))
rexmt = tcp_rexmit_initial * tcp_backoff[tp->t_rxtshift];
else
rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
TCPT_RANGESET(tp->t_rxtcur, rexmt,
tp->t_rttmin, TCPTV_REXMTMAX);
/*
* We enter the path for PLMTUD if connection is established or, if
* connection is FIN_WAIT_1 status, reason for the last is that if
* amount of data we send is very small, we could send it in couple of
* packets and process straight to FIN. In that case we won't catch
* ESTABLISHED state.
*/
if (V_tcp_pmtud_blackhole_detect && (((tp->t_state == TCPS_ESTABLISHED))
|| (tp->t_state == TCPS_FIN_WAIT_1))) {
#ifdef INET6
int isipv6;
#endif
/*
* Idea here is that at each stage of mtu probe (usually, 1448
* -> 1188 -> 524) should be given 2 chances to recover before
* further clamping down. 'tp->t_rxtshift % 2 == 0' should
* take care of that.
*/
if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
(TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
(tp->t_rxtshift >= 2 && tp->t_rxtshift < 6 &&
tp->t_rxtshift % 2 == 0)) {
/*
* Enter Path MTU Black-hole Detection mechanism:
* - Disable Path MTU Discovery (IP "DF" bit).
* - Reduce MTU to lower value than what we
* negotiated with peer.
*/
if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) == 0) {
/* Record that we may have found a black hole. */
tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
/* Keep track of previous MSS. */
tp->t_pmtud_saved_maxseg = tp->t_maxseg;
}
/*
* Reduce the MSS to blackhole value or to the default
* in an attempt to retransmit.
*/
#ifdef INET6
isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? 1 : 0;
if (isipv6 &&
tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss) {
/* Use the sysctl tuneable blackhole MSS. */
tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss;
TCPSTAT_INC(tcps_pmtud_blackhole_activated);
} else if (isipv6) {
/* Use the default MSS. */
tp->t_maxseg = V_tcp_v6mssdflt;
/*
* Disable Path MTU Discovery when we switch to
* minmss.
*/
tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
}
#endif
#if defined(INET6) && defined(INET)
else
#endif
#ifdef INET
if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss) {
/* Use the sysctl tuneable blackhole MSS. */
tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
TCPSTAT_INC(tcps_pmtud_blackhole_activated);
} else {
/* Use the default MSS. */
tp->t_maxseg = V_tcp_mssdflt;
/*
* Disable Path MTU Discovery when we switch to
* minmss.
*/
tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
}
#endif
/*
* Reset the slow-start flight size
* as it may depend on the new MSS.
*/
if (CC_ALGO(tp)->conn_init != NULL)
CC_ALGO(tp)->conn_init(tp->ccv);
} else {
/*
* If further retransmissions are still unsuccessful
* with a lowered MTU, maybe this isn't a blackhole and
* we restore the previous MSS and blackhole detection
* flags.
* The limit '6' is determined by giving each probe
* stage (1448, 1188, 524) 2 chances to recover.
*/
if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
(tp->t_rxtshift >= 6)) {
tp->t_flags2 |= TF2_PLPMTU_PMTUD;
tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
tp->t_maxseg = tp->t_pmtud_saved_maxseg;
TCPSTAT_INC(tcps_pmtud_blackhole_failed);
/*
* Reset the slow-start flight size as it
* may depend on the new MSS.
*/
if (CC_ALGO(tp)->conn_init != NULL)
CC_ALGO(tp)->conn_init(tp->ccv);
}
}
}
/*
* Disable RFC1323 and SACK if we haven't got any response to
* our third SYN to work-around some broken terminal servers
* (most of which have hopefully been retired) that have bad VJ
* header compression code which trashes TCP segments containing
* unknown-to-them TCP options.
*/
if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
(tp->t_rxtshift == 3))
tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
/*
* If we backed off this far, notify the L3 protocol that we're having
* connection problems.
*/
if (tp->t_rxtshift > TCP_RTT_INVALIDATE) {
#ifdef INET6
if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
in6_losing(tp->t_inpcb);
else
#endif
in_losing(tp->t_inpcb);
}
tp->snd_nxt = tp->snd_una;
tp->snd_recover = tp->snd_max;
/*
* Force a segment to be sent.
*/
tp->t_flags |= TF_ACKNOW;
/*
* If timing a segment in this window, stop the timer.
*/
tp->t_rtttime = 0;
cc_cong_signal(tp, NULL, CC_RTO);
(void) tp->t_fb->tfb_tcp_output(tp);
#ifdef TCPDEBUG
if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
PRU_SLOWTIMO);
#endif
TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
INP_WUNLOCK(inp);
out:
CURVNET_RESTORE();
}
void
tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
{
struct callout *t_callout;
timeout_t *f_callout;
struct inpcb *inp = tp->t_inpcb;
int cpu = inp_to_cpuid(inp);
#ifdef TCP_OFFLOAD
if (tp->t_flags & TF_TOE)
return;
#endif
if (tp->t_timers->tt_flags & TT_STOPPED)
return;
switch (timer_type) {
case TT_DELACK:
t_callout = &tp->t_timers->tt_delack;
f_callout = tcp_timer_delack;
break;
case TT_REXMT:
t_callout = &tp->t_timers->tt_rexmt;
f_callout = tcp_timer_rexmt;
break;
case TT_PERSIST:
t_callout = &tp->t_timers->tt_persist;
f_callout = tcp_timer_persist;
break;
case TT_KEEP:
t_callout = &tp->t_timers->tt_keep;
f_callout = tcp_timer_keep;
break;
case TT_2MSL:
t_callout = &tp->t_timers->tt_2msl;
f_callout = tcp_timer_2msl;
break;
default:
if (tp->t_fb->tfb_tcp_timer_activate) {
tp->t_fb->tfb_tcp_timer_activate(tp, timer_type, delta);
return;
}
panic("tp %p bad timer_type %#x", tp, timer_type);
}
if (delta == 0) {
callout_stop(t_callout);
} else {
callout_reset_on(t_callout, delta, f_callout, tp, cpu);
}
}
int
tcp_timer_active(struct tcpcb *tp, uint32_t timer_type)
{
struct callout *t_callout;
switch (timer_type) {
case TT_DELACK:
t_callout = &tp->t_timers->tt_delack;
break;
case TT_REXMT:
t_callout = &tp->t_timers->tt_rexmt;
break;
case TT_PERSIST:
t_callout = &tp->t_timers->tt_persist;
break;
case TT_KEEP:
t_callout = &tp->t_timers->tt_keep;
break;
case TT_2MSL:
t_callout = &tp->t_timers->tt_2msl;
break;
default:
if (tp->t_fb->tfb_tcp_timer_active) {
return(tp->t_fb->tfb_tcp_timer_active(tp, timer_type));
}
panic("tp %p bad timer_type %#x", tp, timer_type);
}
return callout_active(t_callout);
}
/*
* Stop the timer from running, and apply a flag
* against the timer_flags that will force the
* timer never to run. The flag is needed to assure
* a race does not leave it running and cause
* the timer to possibly restart itself (keep and persist
* especially do this).
*/
int
tcp_timer_suspend(struct tcpcb *tp, uint32_t timer_type)
{
struct callout *t_callout;
uint32_t t_flags;
switch (timer_type) {
case TT_DELACK:
t_flags = TT_DELACK_SUS;
t_callout = &tp->t_timers->tt_delack;
break;
case TT_REXMT:
t_flags = TT_REXMT_SUS;
t_callout = &tp->t_timers->tt_rexmt;
break;
case TT_PERSIST:
t_flags = TT_PERSIST_SUS;
t_callout = &tp->t_timers->tt_persist;
break;
case TT_KEEP:
t_flags = TT_KEEP_SUS;
t_callout = &tp->t_timers->tt_keep;
break;
case TT_2MSL:
t_flags = TT_2MSL_SUS;
t_callout = &tp->t_timers->tt_2msl;
break;
default:
panic("tp:%p bad timer_type 0x%x", tp, timer_type);
}
tp->t_timers->tt_flags |= t_flags;
return (callout_stop(t_callout));
}
void
tcp_timers_unsuspend(struct tcpcb *tp, uint32_t timer_type)
{
switch (timer_type) {
case TT_DELACK:
if (tp->t_timers->tt_flags & TT_DELACK_SUS) {
tp->t_timers->tt_flags &= ~TT_DELACK_SUS;
if (tp->t_flags & TF_DELACK) {
/* Delayed ack timer should be up activate a timer */
tp->t_flags &= ~TF_DELACK;
tcp_timer_activate(tp, TT_DELACK,
tcp_delacktime);
}
}
break;
case TT_REXMT:
if (tp->t_timers->tt_flags & TT_REXMT_SUS) {
tp->t_timers->tt_flags &= ~TT_REXMT_SUS;
if (SEQ_GT(tp->snd_max, tp->snd_una) &&
(tcp_timer_active((tp), TT_PERSIST) == 0) &&
tp->snd_wnd) {
/* We have outstanding data activate a timer */
tcp_timer_activate(tp, TT_REXMT,
tp->t_rxtcur);
}
}
break;
case TT_PERSIST:
if (tp->t_timers->tt_flags & TT_PERSIST_SUS) {
tp->t_timers->tt_flags &= ~TT_PERSIST_SUS;
if (tp->snd_wnd == 0) {
/* Activate the persists timer */
tp->t_rxtshift = 0;
tcp_setpersist(tp);
}
}
break;
case TT_KEEP:
if (tp->t_timers->tt_flags & TT_KEEP_SUS) {
tp->t_timers->tt_flags &= ~TT_KEEP_SUS;
tcp_timer_activate(tp, TT_KEEP,
TCPS_HAVEESTABLISHED(tp->t_state) ?
TP_KEEPIDLE(tp) : TP_KEEPINIT(tp));
}
break;
case TT_2MSL:
if (tp->t_timers->tt_flags &= TT_2MSL_SUS) {
tp->t_timers->tt_flags &= ~TT_2MSL_SUS;
if ((tp->t_state == TCPS_FIN_WAIT_2) &&
((tp->t_inpcb->inp_socket == NULL) ||
(tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE))) {
/* Star the 2MSL timer */
tcp_timer_activate(tp, TT_2MSL,
(tcp_fast_finwait2_recycle) ?
tcp_finwait2_timeout : TP_MAXIDLE(tp));
}
}
break;
default:
panic("tp:%p bad timer_type 0x%x", tp, timer_type);
}
}
void
tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
{
struct callout *t_callout;
tp->t_timers->tt_flags |= TT_STOPPED;
switch (timer_type) {
case TT_DELACK:
t_callout = &tp->t_timers->tt_delack;
break;
case TT_REXMT:
t_callout = &tp->t_timers->tt_rexmt;
break;
case TT_PERSIST:
t_callout = &tp->t_timers->tt_persist;
break;
case TT_KEEP:
t_callout = &tp->t_timers->tt_keep;
break;
case TT_2MSL:
t_callout = &tp->t_timers->tt_2msl;
break;
default:
if (tp->t_fb->tfb_tcp_timer_stop) {
/*
* XXXrrs we need to look at this with the
* stop case below (flags).
*/
tp->t_fb->tfb_tcp_timer_stop(tp, timer_type);
return;
}
panic("tp %p bad timer_type %#x", tp, timer_type);
}
if (callout_async_drain(t_callout, tcp_timer_discard) == 0) {
/*
* Can't stop the callout, defer tcpcb actual deletion
* to the last one. We do this using the async drain
* function and incrementing the count in
*/
tp->t_timers->tt_draincnt++;
}
}
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