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pjsip: Fix deadlock with suspend taskprocessor on masquerade

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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
This commit is contained in:
Alexei Gradinari
2016-08-06 11:57:08 -04:00
parent d78fe8fed0
commit 820879415f
3 changed files with 70 additions and 0 deletions
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29
main/taskprocessor.c
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@@ -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;