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chan_sip.c: Fix reinviteid deadlock potential.

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This patch is part of a series to resolve deadlocks in chan_sip.c.

Stopping a scheduled event can result in a deadlock if the scheduled event
is running when you try to stop the event.  If you hold a lock needed by
the scheduled event while trying to stop the scheduled event then a
deadlock can happen.  The general strategy for resolving the deadlock
potential is to push the actual starting and stopping of the scheduled
events off onto the scheduler/do_monitor() thread by scheduling an
immediate one shot scheduled event.  Some restructuring may be needed
because the code may assume that the start/stop of the scheduled events is
immediate.

ASTERISK-25023

Change-Id: I9c11b9d597468f63916c99e1dabff9f4a46f84c1
This commit is contained in:
Richard Mudgett
2016-03-09 16:34:53 -06:00
parent 38c1cdab2c
commit 43556b800b
1 changed files with 37 additions and 10 deletions
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47
channels/chan_sip.c
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@@ -7041,21 +7041,44 @@ const char *hangup_cause2sip(int cause)
return 0;
}
/* Run by the sched thread. */
static int reinvite_timeout(const void *data)
{
struct sip_pvt *dialog = (struct sip_pvt *) data;
struct ast_channel *owner = sip_pvt_lock_full(dialog);
struct ast_channel *owner;
owner = sip_pvt_lock_full(dialog);
dialog->reinviteid = -1;
check_pendings(dialog);
if (owner) {
ast_channel_unlock(owner);
ast_channel_unref(owner);
}
ao2_unlock(dialog);
dialog_unref(dialog, "unref for reinvite timeout");
sip_pvt_unlock(dialog);
dialog_unref(dialog, "reinviteid complete");
return 0;
}
/* Run by the sched thread. */
static int __stop_reinviteid(const void *data)
{
struct sip_pvt *pvt = (void *) data;
AST_SCHED_DEL_UNREF(sched, pvt->reinviteid,
dialog_unref(pvt, "Stop scheduled reinviteid"));
dialog_unref(pvt, "Stop reinviteid action");
return 0;
}
static void stop_reinviteid(struct sip_pvt *pvt)
{
dialog_ref(pvt, "Stop reinviteid action");
if (ast_sched_add(sched, 0, __stop_reinviteid, pvt) < 0) {
/* Uh Oh. Expect bad behavior. */
dialog_unref(pvt, "Failed to schedule stop reinviteid action");
}
}
/*! \brief sip_hangup: Hangup SIP call
* Part of PBX interface, called from ast_hangup */
static int sip_hangup(struct ast_channel *ast)
@@ -7247,7 +7270,12 @@ static int sip_hangup(struct ast_channel *ast)
* So, just in case, check for pending actions after a bit of time to trigger the pending
* bye that we are setting above */
if (p->ongoing_reinvite && p->reinviteid < 0) {
p->reinviteid = ast_sched_add(sched, 32 * p->timer_t1, reinvite_timeout, dialog_ref(p, "ref for reinvite_timeout"));
p->reinviteid = ast_sched_add(sched, 32 * p->timer_t1,
reinvite_timeout, dialog_ref(p, "Schedule reinviteid"));
if (p->reinviteid < 0) {
/* Uh Oh. Expect bad behavior. */
dialog_unref(p, "Failed to schedule reinviteid");
}
}
}
}
@@ -22935,13 +22963,14 @@ static void check_pendings(struct sip_pvt *p)
if (p->reinviteid > -1) {
/* Outstanding p->reinviteid timeout, so wait... */
return;
} else if (p->invitestate == INV_PROCEEDING || p->invitestate == INV_EARLY_MEDIA) {
}
if (p->invitestate == INV_PROCEEDING || p->invitestate == INV_EARLY_MEDIA) {
/* if we can't BYE, then this is really a pending CANCEL */
p->invitestate = INV_CANCELLED;
transmit_request(p, SIP_CANCEL, p->lastinvite, XMIT_RELIABLE, FALSE);
/* If the cancel occurred on an initial invite, cancel the pending BYE */
if (!ast_test_flag(&p->flags[1], SIP_PAGE2_DIALOG_ESTABLISHED)) {
ast_clear_flag(&p->flags[0], SIP_PENDINGBYE);
ast_clear_flag(&p->flags[0], SIP_PENDINGBYE | SIP_NEEDREINVITE);
}
/* Actually don't destroy us yet, wait for the 487 on our original
INVITE, but do set an autodestruct just in case we never get it. */
@@ -22957,7 +22986,7 @@ static void check_pendings(struct sip_pvt *p)
}
/* Perhaps there is an SD change INVITE outstanding */
transmit_request_with_auth(p, SIP_BYE, 0, XMIT_RELIABLE, TRUE);
ast_clear_flag(&p->flags[0], SIP_PENDINGBYE);
ast_clear_flag(&p->flags[0], SIP_PENDINGBYE | SIP_NEEDREINVITE);
}
sip_scheddestroy(p, DEFAULT_TRANS_TIMEOUT);
} else if (ast_test_flag(&p->flags[0], SIP_NEEDREINVITE)) {
@@ -23249,9 +23278,7 @@ static void handle_response_invite(struct sip_pvt *p, int resp, const char *rest
if ((resp >= 200 && reinvite)) {
p->ongoing_reinvite = 0;
if (p->reinviteid > -1) {
AST_SCHED_DEL_UNREF(sched, p->reinviteid, dialog_unref(p, "unref dialog for reinvite timeout because of a final response"));
}
stop_reinviteid(p);
}
/* Final response, clear out pending invite */