[Asterisk-code-review] chan sip.c: Fix packet retransid deadlock potential. (asterisk[13])

[Richard Mudgett]

Hello Mark Michelson, Joshua Colp,

I'd like you to reexamine a change.  Please visit

    https://gerrit.asterisk.org/2397

to look at the new patch set (#3).

Change subject: chan_sip.c: Fix packet retransid deadlock potential.
......................................................................

chan_sip.c: Fix packet retransid 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.

* Fix retrans_pkt() to call check_pendings() with both the owner channel
and the private objects locked as required.

* Refactor dialog retransmission packet list to safely remove packet
nodes.  The list nodes are now ao2 objects.  The list has a ref and the
scheduled entry has a ref.

ASTERISK-25023

Change-Id: I50926d81be53f4cd3d572a3292cd25f563f59641
---
M channels/chan_sip.c
1 file changed, 96 insertions(+), 79 deletions(-)


  git pull ssh://gerrit.asterisk.org:29418/asterisk refs/changes/97/2397/3
-- 
To view, visit https://gerrit.asterisk.org/2397
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I50926d81be53f4cd3d572a3292cd25f563f59641
Gerrit-PatchSet: 3
Gerrit-Project: asterisk
Gerrit-Branch: 13
Gerrit-Owner: Richard Mudgett <rmudgett at digium.com>
Gerrit-Reviewer: Anonymous Coward #1000019
Gerrit-Reviewer: Joshua Colp <jcolp at digium.com>
Gerrit-Reviewer: Mark Michelson <mmichelson at digium.com>