[asterisk-bugs] [Asterisk 0015349]: Deadlock in do_monitor() of chan_sip

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
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https://issues.asterisk.org/view.php?id=15349 
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Reported By:                samy
Assigned To:                mmichelson
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Project:                    Asterisk
Issue ID:                   15349
Category:                   Channels/chan_sip/General
Reproducibility:            have not tried
Severity:                   major
Priority:                   normal
Status:                     assigned
Asterisk Version:           1.6.0.10 
Regression:                 No 
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!):  
Request Review:              
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Date Submitted:             2009-06-17 22:08 CDT
Last Modified:              2009-06-24 13:17 CDT
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Summary:                    Deadlock in do_monitor() of chan_sip
Description: 
Unfortunately I have no steps to reproduce this. Had about 30 calls going
through, all calls are SIP, and randomly ran into a SIP deadlock (`sip show
channels` would cause console to hang, no new SIP calls would begin).

It sort of looks like `dialoglist` is an infinite loop (every member
points to at least one other member, there is never a ->next that points to
null), but I don't see how that could happen in the code so I'm not sure.

I did get `core show locks` output a few times, and I have a modified
version that provides the time of the last time each lock was
locked/unlocked. This is interesting because we can see lock
https://issues.asterisk.org/view.php?id=0 never
changes and is held for multiple minutes before I restart, but lock
https://issues.asterisk.org/view.php?id=1
changes constantly.

The fact that lock https://issues.asterisk.org/view.php?id=1 (lock on
dialog->sip_pvt) is constantly changing in
do_monitor makes me think `dialoglist` is an infinite loop.
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 (0106918) mmichelson (administrator) - 2009-06-24 13:17
 https://issues.asterisk.org/view.php?id=15349#c106918 
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After a second look through the code, I still cannot see how the dialoglist
could become looped. Still, an infinite loop is the only explanation that
makes any sense given the lock output you have provided. What patches have
you applied to chan_sip.c? At this point, the only thing I can think of
that might be causing this is a patch added on. 

Issue History 
Date Modified    Username       Field                    Change               
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2009-06-24 13:17 mmichelson     Note Added: 0106918                          
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