mirror/freebsd
1
0
Fork 0
mirror of https://git.FreeBSD.org/src.git synced 2024-12-04 09:09:56 +00:00
Code Issues Releases Activity
22ae8ae1f4
freebsd/sys/netinet/tcp_timewait.c
Pedro F. Giffuni 51369649b0 sys: further adoption of SPDX licensing ID tags. 
Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.
2017-11-20 19:43:44 +00:00

764 lines
19 KiB
C
Raw Blame History

/*-
* 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_subr.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 <sys/param.h>
#include <sys/systm.h>
#include <sys/callout.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#ifndef INVARIANTS
#include <sys/syslog.h>
#endif
#include <sys/protosw.h>
#include <sys/random.h>
#include <vm/uma.h>
#include <net/route.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/vnet.h>
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netinet/ip_var.h>
#ifdef INET6
#include <netinet/ip6.h>
#include <netinet6/in6_pcb.h>
#include <netinet6/ip6_var.h>
#include <netinet6/scope6_var.h>
#include <netinet6/nd6.h>
#endif
#include <netinet/tcp.h>
#include <netinet/tcp_fsm.h>
#include <netinet/tcp_seq.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#ifdef INET6
#include <netinet6/tcp6_var.h>
#endif
#include <netinet/tcpip.h>
#ifdef TCPDEBUG
#include <netinet/tcp_debug.h>
#endif
#ifdef INET6
#include <netinet6/ip6protosw.h>
#endif
#include <machine/in_cksum.h>
#include <security/mac/mac_framework.h>
static VNET_DEFINE(uma_zone_t, tcptw_zone);
#define V_tcptw_zone VNET(tcptw_zone)
static int maxtcptw;
/*
* The timed wait queue contains references to each of the TCP sessions
* currently in the TIME_WAIT state. The queue pointers, including the
* queue pointers in each tcptw structure, are protected using the global
* timewait lock, which must be held over queue iteration and modification.
*
* Rules on tcptw usage:
* - a inpcb is always freed _after_ its tcptw
* - a tcptw relies on its inpcb reference counting for memory stability
* - a tcptw is dereferenceable only while its inpcb is locked
*/
static VNET_DEFINE(TAILQ_HEAD(, tcptw), twq_2msl);
#define V_twq_2msl VNET(twq_2msl)
/* Global timewait lock */
static VNET_DEFINE(struct rwlock, tw_lock);
#define V_tw_lock VNET(tw_lock)
#define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0)
#define TW_LOCK_DESTROY(tw) rw_destroy(&(tw))
#define TW_RLOCK(tw) rw_rlock(&(tw))
#define TW_WLOCK(tw) rw_wlock(&(tw))
#define TW_RUNLOCK(tw) rw_runlock(&(tw))
#define TW_WUNLOCK(tw) rw_wunlock(&(tw))
#define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED)
#define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED)
#define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED)
#define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED)
static void tcp_tw_2msl_reset(struct tcptw *, int);
static void tcp_tw_2msl_stop(struct tcptw *, int);
static int tcp_twrespond(struct tcptw *, int);
static int
tcptw_auto_size(void)
{
int halfrange;
/*
* Max out at half the ephemeral port range so that TIME_WAIT
* sockets don't tie up too many ephemeral ports.
*/
if (V_ipport_lastauto > V_ipport_firstauto)
halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2;
else
halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2;
/* Protect against goofy port ranges smaller than 32. */
return (imin(imax(halfrange, 32), maxsockets / 5));
}
static int
sysctl_maxtcptw(SYSCTL_HANDLER_ARGS)
{
int error, new;
if (maxtcptw == 0)
new = tcptw_auto_size();
else
new = maxtcptw;
error = sysctl_handle_int(oidp, &new, 0, req);
if (error == 0 && req->newptr)
if (new >= 32) {
maxtcptw = new;
uma_zone_set_max(V_tcptw_zone, maxtcptw);
}
return (error);
}
SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, CTLTYPE_INT|CTLFLAG_RW,
&maxtcptw, 0, sysctl_maxtcptw, "IU",
"Maximum number of compressed TCP TIME_WAIT entries");
VNET_DEFINE(int, nolocaltimewait) = 0;
#define V_nolocaltimewait VNET(nolocaltimewait)
SYSCTL_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(nolocaltimewait), 0,
"Do not create compressed TCP TIME_WAIT entries for local connections");
void
tcp_tw_zone_change(void)
{
if (maxtcptw == 0)
uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
}
void
tcp_tw_init(void)
{
V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw),
NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw);
if (maxtcptw == 0)
uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
else
uma_zone_set_max(V_tcptw_zone, maxtcptw);
TAILQ_INIT(&V_twq_2msl);
TW_LOCK_INIT(V_tw_lock, "tcptw");
}
#ifdef VIMAGE
void
tcp_tw_destroy(void)
{
struct tcptw *tw;
INP_INFO_RLOCK(&V_tcbinfo);
while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL)
tcp_twclose(tw, 0);
INP_INFO_RUNLOCK(&V_tcbinfo);
TW_LOCK_DESTROY(V_tw_lock);
uma_zdestroy(V_tcptw_zone);
}
#endif
/*
* Move a TCP connection into TIME_WAIT state.
* tcbinfo is locked.
* inp is locked, and is unlocked before returning.
*/
void
tcp_twstart(struct tcpcb *tp)
{
struct tcptw *tw;
struct inpcb *inp = tp->t_inpcb;
int acknow;
struct socket *so;
#ifdef INET6
int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6;
#endif
INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
INP_WLOCK_ASSERT(inp);
/* A dropped inp should never transition to TIME_WAIT state. */
KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: "
"(inp->inp_flags & INP_DROPPED) != 0"));
if (V_nolocaltimewait) {
int error = 0;
#ifdef INET6
if (isipv6)
error = in6_localaddr(&inp->in6p_faddr);
#endif
#if defined(INET6) && defined(INET)
else
#endif
#ifdef INET
error = in_localip(inp->inp_faddr);
#endif
if (error) {
tp = tcp_close(tp);
if (tp != NULL)
INP_WUNLOCK(inp);
return;
}
}
/*
* For use only by DTrace. We do not reference the state
* after this point so modifying it in place is not a problem.
*/
tcp_state_change(tp, TCPS_TIME_WAIT);
tw = uma_zalloc(V_tcptw_zone, M_NOWAIT);
if (tw == NULL) {
/*
* Reached limit on total number of TIMEWAIT connections
* allowed. Remove a connection from TIMEWAIT queue in LRU
* fashion to make room for this connection.
*
* XXX: Check if it possible to always have enough room
* in advance based on guarantees provided by uma_zalloc().
*/
tw = tcp_tw_2msl_scan(1);
if (tw == NULL) {
tp = tcp_close(tp);
if (tp != NULL)
INP_WUNLOCK(inp);
return;
}
}
/*
* The tcptw will hold a reference on its inpcb until tcp_twclose
* is called
*/
tw->tw_inpcb = inp;
in_pcbref(inp); /* Reference from tw */
/*
* Recover last window size sent.
*/
if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt))
tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale;
else
tw->last_win = 0;
/*
* Set t_recent if timestamps are used on the connection.
*/
if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) ==
(TF_REQ_TSTMP|TF_RCVD_TSTMP)) {
tw->t_recent = tp->ts_recent;
tw->ts_offset = tp->ts_offset;
} else {
tw->t_recent = 0;
tw->ts_offset = 0;
}
tw->snd_nxt = tp->snd_nxt;
tw->rcv_nxt = tp->rcv_nxt;
tw->iss = tp->iss;
tw->irs = tp->irs;
tw->t_starttime = tp->t_starttime;
tw->tw_time = 0;
/* XXX
* If this code will
* be used for fin-wait-2 state also, then we may need
* a ts_recent from the last segment.
*/
acknow = tp->t_flags & TF_ACKNOW;
/*
* First, discard tcpcb state, which includes stopping its timers and
* freeing it. tcp_discardcb() used to also release the inpcb, but
* that work is now done in the caller.
*
* Note: soisdisconnected() call used to be made in tcp_discardcb(),
* and might not be needed here any longer.
*/
tcp_discardcb(tp);
so = inp->inp_socket;
soisdisconnected(so);
tw->tw_cred = crhold(so->so_cred);
SOCK_LOCK(so);
tw->tw_so_options = so->so_options;
SOCK_UNLOCK(so);
if (acknow)
tcp_twrespond(tw, TH_ACK);
inp->inp_ppcb = tw;
inp->inp_flags |= INP_TIMEWAIT;
TCPSTATES_INC(TCPS_TIME_WAIT);
tcp_tw_2msl_reset(tw, 0);
/*
* If the inpcb owns the sole reference to the socket, then we can
* detach and free the socket as it is not needed in time wait.
*/
if (inp->inp_flags & INP_SOCKREF) {
KASSERT(so->so_state & SS_PROTOREF,
("tcp_twstart: !SS_PROTOREF"));
inp->inp_flags &= ~INP_SOCKREF;
INP_WUNLOCK(inp);
SOCK_LOCK(so);
so->so_state &= ~SS_PROTOREF;
sofree(so);
} else
INP_WUNLOCK(inp);
}
/*
* Returns 1 if the TIME_WAIT state was killed and we should start over,
* looking for a pcb in the listen state. Returns 0 otherwise.
*/
int
tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unused, struct tcphdr *th,
struct mbuf *m, int tlen)
{
struct tcptw *tw;
int thflags;
tcp_seq seq;
INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
INP_WLOCK_ASSERT(inp);
/*
* XXXRW: Time wait state for inpcb has been recycled, but inpcb is
* still present. This is undesirable, but temporarily necessary
* until we work out how to handle inpcb's who's timewait state has
* been removed.
*/
tw = intotw(inp);
if (tw == NULL)
goto drop;
thflags = th->th_flags;
/*
* NOTE: for FIN_WAIT_2 (to be added later),
* must validate sequence number before accepting RST
*/
/*
* If the segment contains RST:
* Drop the segment - see Stevens, vol. 2, p. 964 and
* RFC 1337.
*/
if (thflags & TH_RST)
goto drop;
#if 0
/* PAWS not needed at the moment */
/*
* RFC 1323 PAWS: If we have a timestamp reply on this segment
* and it's less than ts_recent, drop it.
*/
if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent &&
TSTMP_LT(to.to_tsval, tp->ts_recent)) {
if ((thflags & TH_ACK) == 0)
goto drop;
goto ack;
}
/*
* ts_recent is never updated because we never accept new segments.
*/
#endif
/*
* If a new connection request is received
* while in TIME_WAIT, drop the old connection
* and start over if the sequence numbers
* are above the previous ones.
*/
if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) {
tcp_twclose(tw, 0);
return (1);
}
/*
* Drop the segment if it does not contain an ACK.
*/
if ((thflags & TH_ACK) == 0)
goto drop;
/*
* Reset the 2MSL timer if this is a duplicate FIN.
*/
if (thflags & TH_FIN) {
seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0);
if (seq + 1 == tw->rcv_nxt)
tcp_tw_2msl_reset(tw, 1);
}
/*
* Acknowledge the segment if it has data or is not a duplicate ACK.
*/
if (thflags != TH_ACK || tlen != 0 ||
th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt)
tcp_twrespond(tw, TH_ACK);
drop:
INP_WUNLOCK(inp);
m_freem(m);
return (0);
}
void
tcp_twclose(struct tcptw *tw, int reuse)
{
struct socket *so;
struct inpcb *inp;
/*
* At this point, we are in one of two situations:
*
* (1) We have no socket, just an inpcb<->twtcp pair. We can free
* all state.
*
* (2) We have a socket -- if we own a reference, release it and
* notify the socket layer.
*/
inp = tw->tw_inpcb;
KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait"));
KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw"));
INP_INFO_RLOCK_ASSERT(&V_tcbinfo); /* in_pcbfree() */
INP_WLOCK_ASSERT(inp);
tcp_tw_2msl_stop(tw, reuse);
inp->inp_ppcb = NULL;
in_pcbdrop(inp);
so = inp->inp_socket;
if (so != NULL) {
/*
* If there's a socket, handle two cases: first, we own a
* strong reference, which we will now release, or we don't
* in which case another reference exists (XXXRW: think
* about this more), and we don't need to take action.
*/
if (inp->inp_flags & INP_SOCKREF) {
inp->inp_flags &= ~INP_SOCKREF;
INP_WUNLOCK(inp);
SOCK_LOCK(so);
KASSERT(so->so_state & SS_PROTOREF,
("tcp_twclose: INP_SOCKREF && !SS_PROTOREF"));
so->so_state &= ~SS_PROTOREF;
sofree(so);
} else {
/*
* If we don't own the only reference, the socket and
* inpcb need to be left around to be handled by
* tcp_usr_detach() later.
*/
INP_WUNLOCK(inp);
}
} else {
/*
* The socket has been already cleaned-up for us, only free the
* inpcb.
*/
in_pcbfree(inp);
}
TCPSTAT_INC(tcps_closed);
}
static int
tcp_twrespond(struct tcptw *tw, int flags)
{
struct inpcb *inp = tw->tw_inpcb;
#if defined(INET6) || defined(INET)
struct tcphdr *th = NULL;
#endif
struct mbuf *m;
#ifdef INET
struct ip *ip = NULL;
#endif
u_int hdrlen, optlen;
int error = 0; /* Keep compiler happy */
struct tcpopt to;
#ifdef INET6
struct ip6_hdr *ip6 = NULL;
int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6;
#endif
hdrlen = 0; /* Keep compiler happy */
INP_WLOCK_ASSERT(inp);
m = m_gethdr(M_NOWAIT, MT_DATA);
if (m == NULL)
return (ENOBUFS);
m->m_data += max_linkhdr;
#ifdef MAC
mac_inpcb_create_mbuf(inp, m);
#endif
#ifdef INET6
if (isipv6) {
hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
ip6 = mtod(m, struct ip6_hdr *);
th = (struct tcphdr *)(ip6 + 1);
tcpip_fillheaders(inp, ip6, th);
}
#endif
#if defined(INET6) && defined(INET)
else
#endif
#ifdef INET
{
hdrlen = sizeof(struct tcpiphdr);
ip = mtod(m, struct ip *);
th = (struct tcphdr *)(ip + 1);
tcpip_fillheaders(inp, ip, th);
}
#endif
to.to_flags = 0;
/*
* Send a timestamp and echo-reply if both our side and our peer
* have sent timestamps in our SYN's and this is not a RST.
*/
if (tw->t_recent && flags == TH_ACK) {
to.to_flags |= TOF_TS;
to.to_tsval = tcp_ts_getticks() + tw->ts_offset;
to.to_tsecr = tw->t_recent;
}
optlen = tcp_addoptions(&to, (u_char *)(th + 1));
m->m_len = hdrlen + optlen;
m->m_pkthdr.len = m->m_len;
KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small"));
th->th_seq = htonl(tw->snd_nxt);
th->th_ack = htonl(tw->rcv_nxt);
th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
th->th_flags = flags;
th->th_win = htons(tw->last_win);
m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
#ifdef INET6
if (isipv6) {
m->m_pkthdr.csum_flags = CSUM_TCP_IPV6;
th->th_sum = in6_cksum_pseudo(ip6,
sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0);
ip6->ip6_hlim = in6_selecthlim(inp, NULL);
error = ip6_output(m, inp->in6p_outputopts, NULL,
(tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp);
}
#endif
#if defined(INET6) && defined(INET)
else
#endif
#ifdef INET
{
m->m_pkthdr.csum_flags = CSUM_TCP;
th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP));
ip->ip_len = htons(m->m_pkthdr.len);
if (V_path_mtu_discovery)
ip->ip_off |= htons(IP_DF);
error = ip_output(m, inp->inp_options, NULL,
((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0),
NULL, inp);
}
#endif
if (flags & TH_ACK)
TCPSTAT_INC(tcps_sndacks);
else
TCPSTAT_INC(tcps_sndctrl);
TCPSTAT_INC(tcps_sndtotal);
return (error);
}
static void
tcp_tw_2msl_reset(struct tcptw *tw, int rearm)
{
INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
INP_WLOCK_ASSERT(tw->tw_inpcb);
TW_WLOCK(V_tw_lock);
if (rearm)
TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
tw->tw_time = ticks + 2 * tcp_msl;
TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl);
TW_WUNLOCK(V_tw_lock);
}
static void
tcp_tw_2msl_stop(struct tcptw *tw, int reuse)
{
struct ucred *cred;
struct inpcb *inp;
int released;
INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
TW_WLOCK(V_tw_lock);
inp = tw->tw_inpcb;
tw->tw_inpcb = NULL;
TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
cred = tw->tw_cred;
tw->tw_cred = NULL;
TW_WUNLOCK(V_tw_lock);
if (cred != NULL)
crfree(cred);
released = in_pcbrele_wlocked(inp);
KASSERT(!released, ("%s: inp should not be released here", __func__));
if (!reuse)
uma_zfree(V_tcptw_zone, tw);
TCPSTATES_DEC(TCPS_TIME_WAIT);
}
struct tcptw *
tcp_tw_2msl_scan(int reuse)
{
struct tcptw *tw;
struct inpcb *inp;
#ifdef INVARIANTS
if (reuse) {
/*
* Exclusive pcbinfo lock is not required in reuse case even if
* two inpcb locks can be acquired simultaneously:
* - the inpcb transitioning to TIME_WAIT state in
* tcp_tw_start(),
* - the inpcb closed by tcp_twclose().
*
* It is because only inpcbs in FIN_WAIT2 or CLOSING states can
* transition in TIME_WAIT state. Then a pcbcb cannot be in
* TIME_WAIT list and transitioning to TIME_WAIT state at same
* time.
*/
INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
}
#endif
for (;;) {
TW_RLOCK(V_tw_lock);
tw = TAILQ_FIRST(&V_twq_2msl);
if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) {
TW_RUNLOCK(V_tw_lock);
break;
}
KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL",
__func__));
inp = tw->tw_inpcb;
in_pcbref(inp);
TW_RUNLOCK(V_tw_lock);
if (INP_INFO_TRY_RLOCK(&V_tcbinfo)) {
INP_WLOCK(inp);
tw = intotw(inp);
if (in_pcbrele_wlocked(inp)) {
if (__predict_true(tw == NULL)) {
INP_INFO_RUNLOCK(&V_tcbinfo);
continue;
} else {
/* This should not happen as in TIMEWAIT
* state the inp should not be destroyed
* before its tcptw. If INVARIANTS is
* defined panic.
*/
#ifdef INVARIANTS
panic("%s: Panic before an infinite "
"loop: INP_TIMEWAIT && (INP_FREED "
"|| inp last reference) && tw != "
"NULL", __func__);
#else
log(LOG_ERR, "%s: Avoid an infinite "
"loop: INP_TIMEWAIT && (INP_FREED "
"|| inp last reference) && tw != "
"NULL", __func__);
#endif
INP_INFO_RUNLOCK(&V_tcbinfo);
break;
}
}
if (tw == NULL) {
/* tcp_twclose() has already been called */
INP_WUNLOCK(inp);
INP_INFO_RUNLOCK(&V_tcbinfo);
continue;
}
tcp_twclose(tw, reuse);
INP_INFO_RUNLOCK(&V_tcbinfo);
if (reuse)
return tw;
} else {
/* INP_INFO lock is busy, continue later. */
INP_WLOCK(inp);
if (!in_pcbrele_wlocked(inp))
INP_WUNLOCK(inp);
break;
}
}
return NULL;
}
Reference in New Issue View Git Blame Copy Permalink