chan_sip.c: Fix waitid deadlock potential.
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. * Made always run check_pendings() under the scheduler thread so scheduler ids can be checked safely. ASTERISK-25023 Change-Id: Ia834d6edd5bdb47c163e4ecf884428a4a8b17d52
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@ -1512,6 +1512,7 @@ static int __sip_subscribe_mwi_do(struct sip_subscription_mwi *mwi);
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/* Scheduler id start/stop/reschedule functions. */
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static void stop_provisional_keepalive(struct sip_pvt *pvt);
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static void do_stop_session_timer(struct sip_pvt *pvt);
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static void stop_reinvite_retry(struct sip_pvt *pvt);
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/*! \brief Definition of this channel for PBX channel registration */
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struct ast_channel_tech sip_tech = {
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@ -7223,7 +7224,7 @@ static int sip_hangup(struct ast_channel *ast)
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but we can't send one while we have "INVITE" outstanding. */
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ast_set_flag(&p->flags[0], SIP_PENDINGBYE);
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ast_clear_flag(&p->flags[0], SIP_NEEDREINVITE);
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AST_SCHED_DEL_UNREF(sched, p->waitid, dialog_unref(p, "when you delete the waitid sched, you should dec the refcount for the stored dialog ptr"));
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stop_reinvite_retry(p);
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sip_cancel_destroy(p);
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/* If we have an ongoing reinvite, there is a chance that we have gotten a provisional
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@ -22948,10 +22949,13 @@ static void parse_moved_contact(struct sip_pvt *p, struct sip_request *req, char
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}
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}
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/*! \brief Check pending actions on SIP call
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/*!
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* \brief Check pending actions on SIP call
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*
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* \note both sip_pvt and sip_pvt's owner channel (if present)
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* must be locked for this function.
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*
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* \note Run by the sched thread.
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*/
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static void check_pendings(struct sip_pvt *p)
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{
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@ -22986,7 +22990,11 @@ static void check_pendings(struct sip_pvt *p)
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sip_scheddestroy(p, DEFAULT_TRANS_TIMEOUT);
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} else if (ast_test_flag(&p->flags[0], SIP_NEEDREINVITE)) {
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/* if we can't REINVITE, hold it for later */
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if (p->pendinginvite || p->invitestate == INV_CALLING || p->invitestate == INV_PROCEEDING || p->invitestate == INV_EARLY_MEDIA || p->waitid > -1) {
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if (p->pendinginvite
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|| p->invitestate == INV_CALLING
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|| p->invitestate == INV_PROCEEDING
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|| p->invitestate == INV_EARLY_MEDIA
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|| p->waitid > -1) {
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ast_debug(2, "NOT Sending pending reinvite (yet) on '%s'\n", p->callid);
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} else {
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ast_debug(2, "Sending pending reinvite on '%s'\n", p->callid);
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@ -22997,10 +23005,39 @@ static void check_pendings(struct sip_pvt *p)
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}
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}
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/*! \brief Reset the NEEDREINVITE flag after waiting when we get 491 on a Re-invite
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to avoid race conditions between asterisk servers.
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Called from the scheduler.
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*/
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/* Run by the sched thread. */
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static int __sched_check_pendings(const void *data)
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{
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struct sip_pvt *pvt = (void *) data;
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struct ast_channel *owner;
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owner = sip_pvt_lock_full(pvt);
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check_pendings(pvt);
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if (owner) {
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ast_channel_unlock(owner);
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ast_channel_unref(owner);
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}
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sip_pvt_unlock(pvt);
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dialog_unref(pvt, "Check pending actions action");
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return 0;
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}
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static void sched_check_pendings(struct sip_pvt *pvt)
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{
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dialog_ref(pvt, "Check pending actions action");
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if (ast_sched_add(sched, 0, __sched_check_pendings, pvt) < 0) {
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/* Uh Oh. Expect bad behavior. */
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dialog_unref(pvt, "Failed to schedule check pending actions action");
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}
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}
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/*!
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* \brief Reset the NEEDREINVITE flag after waiting when we get 491 on a Re-invite
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* to avoid race conditions between asterisk servers.
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*
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* \note Run by the sched thread.
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*/
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static int sip_reinvite_retry(const void *data)
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{
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struct sip_pvt *p = (struct sip_pvt *) data;
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@ -23019,10 +23056,30 @@ static int sip_reinvite_retry(const void *data)
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if (owner) {
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ast_channel_unlock(owner);
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}
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dialog_unref(p, "unref the dialog ptr from sip_reinvite_retry, because it held a dialog ptr");
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dialog_unref(p, "Schedule waitid complete");
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return 0;
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}
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/* Run by the sched thread. */
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static int __stop_reinvite_retry(const void *data)
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{
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struct sip_pvt *pvt = (void *) data;
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AST_SCHED_DEL_UNREF(sched, pvt->waitid,
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dialog_unref(pvt, "Stop scheduled waitid"));
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dialog_unref(pvt, "Stop reinvite retry action");
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return 0;
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}
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static void stop_reinvite_retry(struct sip_pvt *pvt)
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{
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dialog_ref(pvt, "Stop reinvite retry action");
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if (ast_sched_add(sched, 0, __stop_reinvite_retry, pvt) < 0) {
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/* Uh Oh. Expect bad behavior. */
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dialog_unref(pvt, "Failed to schedule stop reinvite retry action");
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}
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}
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/*!
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* \brief Handle authentication challenge for SIP UPDATE
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*
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@ -23247,7 +23304,7 @@ static void handle_response_invite(struct sip_pvt *p, int resp, const char *rest
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if (!req->ignore && p->invitestate != INV_CANCELLED) {
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sip_cancel_destroy(p);
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}
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check_pendings(p);
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sched_check_pendings(p);
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break;
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case 180: /* 180 Ringing */
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@ -23305,7 +23362,7 @@ static void handle_response_invite(struct sip_pvt *p, int resp, const char *rest
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}
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ast_rtp_instance_activate(p->rtp);
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}
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check_pendings(p);
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sched_check_pendings(p);
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break;
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case 181: /* Call Is Being Forwarded */
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@ -23338,7 +23395,7 @@ static void handle_response_invite(struct sip_pvt *p, int resp, const char *rest
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ast_party_redirecting_free(&redirecting);
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sip_handle_cc(p, req, AST_CC_CCNR);
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}
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check_pendings(p);
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sched_check_pendings(p);
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break;
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case 183: /* Session progress */
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@ -23399,7 +23456,7 @@ static void handle_response_invite(struct sip_pvt *p, int resp, const char *rest
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ast_queue_control(p->owner, AST_CONTROL_RINGING);
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}
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}
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check_pendings(p);
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sched_check_pendings(p);
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break;
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case 200: /* 200 OK on invite - someone's answering our call */
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@ -23550,7 +23607,7 @@ static void handle_response_invite(struct sip_pvt *p, int resp, const char *rest
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p->invitestate = INV_TERMINATED;
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ast_set_flag(&p->flags[1], SIP_PAGE2_DIALOG_ESTABLISHED);
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xmitres = transmit_request(p, SIP_ACK, seqno, XMIT_UNRELIABLE, TRUE);
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check_pendings(p);
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sched_check_pendings(p);
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break;
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case 407: /* Proxy authentication */
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@ -23662,7 +23719,7 @@ static void handle_response_invite(struct sip_pvt *p, int resp, const char *rest
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update_call_counter(p, DEC_CALL_LIMIT);
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append_history(p, "Hangup", "Got 487 on CANCEL request from us on call without owner. Killing this dialog.");
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}
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check_pendings(p);
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sched_check_pendings(p);
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sip_scheddestroy(p, DEFAULT_TRANS_TIMEOUT);
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break;
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case 415: /* Unsupported media type */
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@ -23694,6 +23751,7 @@ static void handle_response_invite(struct sip_pvt *p, int resp, const char *rest
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/* Reset the flag after a while
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*/
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int wait;
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/* RFC 3261, if owner of call, wait between 2.1 to 4 seconds,
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* if not owner of call, wait 0 to 2 seconds */
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if (p->outgoing_call) {
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@ -23701,7 +23759,12 @@ static void handle_response_invite(struct sip_pvt *p, int resp, const char *rest
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} else {
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wait = ast_random() % 2000;
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}
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p->waitid = ast_sched_add(sched, wait, sip_reinvite_retry, dialog_ref(p, "passing dialog ptr into sched structure based on waitid for sip_reinvite_retry."));
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dialog_ref(p, "Schedule waitid for sip_reinvite_retry.");
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p->waitid = ast_sched_add(sched, wait, sip_reinvite_retry, p);
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if (p->waitid < 0) {
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/* Uh Oh. Expect bad behavior. */
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dialog_ref(p, "Failed to schedule waitid");
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}
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ast_debug(2, "Reinvite race. Scheduled sip_reinvite_retry in %d secs in handle_response_invite (waitid %d, dialog '%s')\n",
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wait, p->waitid, p->callid);
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}
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@ -26914,7 +26977,7 @@ static int handle_request_bye(struct sip_pvt *p, struct sip_request *req)
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/* Destroy any pending invites so we won't try to do another
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* scheduled reINVITE. */
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AST_SCHED_DEL_UNREF(sched, p->waitid, dialog_unref(p, "decrement refcount from sip_destroy because waitid won't be scheduled"));
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stop_reinvite_retry(p);
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return 1;
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}
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@ -28446,7 +28509,7 @@ static int handle_incoming(struct sip_pvt *p, struct sip_request *req, struct as
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ast_queue_control(p->owner, AST_CONTROL_SRCCHANGE);
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}
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}
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check_pendings(p);
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sched_check_pendings(p);
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} else if (p->glareinvite == seqno) {
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/* handle ack for the 491 pending sent for glareinvite */
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p->glareinvite = 0;
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