pjsip: Fix deadlock with suspend taskprocessor on masquerade

If both channels which should be masqueraded
are in the same serializer:
1st channel will be locked waiting condition 'complete'
2nd channel will be locked waiting condition 'suspended'

On heavy load system a chance that both channels will be in
the same serializer 'pjsip/distibutor' is very high.

To reproduce compile res_pjsip/pjsip_distributor.c with
DISTRIBUTOR_POOL_SIZE=1

Steps to reproduce:
1. Party A calls Party B (bridged call 'AB')
2. Party B places Party A on hold
3. Party B calls Voicemail app (non-bridged call 'BV')
4. Party B attended transfers Party A to voicemail using REFER.
5. When asterisk masquerades calls 'AB' and 'BV',
   a deadlock is happened.

This patch adds a suspension indicator to the taskprocessor.
When a session suspends/unsuspends the serializer
it sets the indicator to the appropriate state.
The session checks the suspension indicator before
suspend the serializer.

ASTERISK-26145 #close

Change-Id: Iaaebee60013a58c942ba47b1b4930a63e686663b

1 files changed, 29 insertions, 0 deletions

diff --git a/main/taskprocessor.c b/main/taskprocessor.c
index 2f0124045..4a8497f11 100644
--- a/main/taskprocessor.c
+++ b/main/taskprocessor.c
@@ -91,6 +91,8 @@ struct ast_taskprocessor {
 	unsigned int high_water_warned:1;
 	/*! Indicates that a high water alert is active on this taskprocessor */
 	unsigned int high_water_alert:1;
+	/*! Indicates if the taskprocessor is currently suspended */
+	unsigned int suspended:1;
 };
 
 /*!
@@ -910,6 +912,33 @@ int ast_taskprocessor_push_local(struct ast_taskprocessor *tps, int (*task_exe)(
 	return taskprocessor_push(tps, tps_task_alloc_local(task_exe, datap));
 }
 
+int ast_taskprocessor_suspend(struct ast_taskprocessor *tps)
+{
+	if (tps) {
+		ao2_lock(tps);
+		tps->suspended = 1;
+		ao2_unlock(tps);
+		return 0;
+	}
+	return -1;
+}
+
+int ast_taskprocessor_unsuspend(struct ast_taskprocessor *tps)
+{
+	if (tps) {
+		ao2_lock(tps);
+		tps->suspended = 0;
+		ao2_unlock(tps);
+		return 0;
+	}
+	return -1;
+}
+
+int ast_taskprocessor_is_suspended(struct ast_taskprocessor *tps)
+{
+	return tps ? tps->suspended : -1;
+}
+
 int ast_taskprocessor_execute(struct ast_taskprocessor *tps)
 {
 	struct ast_taskprocessor_local local;