[asterisk-bugs] [Asterisk 0016840]: Deadlock in chan_local when obtaining locks on local_pvt->lock

[Asterisk Bug Tracker]

The following issue has been SUBMITTED. 
====================================================================== 
https://issues.asterisk.org/view.php?id=16840 
====================================================================== 
Reported By:                bzing2
Assigned To:                
====================================================================== 
Project:                    Asterisk
Issue ID:                   16840
Category:                   Channels/chan_local
Reproducibility:            random
Severity:                   block
Priority:                   normal
Status:                     new
Asterisk Version:           1.6.2.2 
JIRA:                        
Regression:                 No 
Reviewboard Link:            
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!):  
Request Review:              
====================================================================== 
Date Submitted:             2010-02-16 11:40 CST
Last Modified:              2010-02-16 11:40 CST
====================================================================== 
Summary:                    Deadlock in chan_local when obtaining locks on
local_pvt->lock
Description: 
Deadlock condition in chan_local when two brideged threads attempt to
obtain
locks to eachothers local_pvt structures in the opposite order.  All
processing of SIP traffic halts when an attempt is made to hangup the
call.

Thread A obtains a lock to its local_pvt->lock when in local_write.  When
in check_bridge a call is made to ast_bridged_channel, this in turn calls
local_bridgedchannel which attempts to obtain a lock on the bridged
channels
local_pvt->lock.

Thread B follows a similar path.  It holds its own lock, and during a call
to
ast_channel_masquerade again local_bridgedchannel is called.  This
attempts to
obtain a lock to the bridged channel.

At this point either side has deadlocked.  Then a user attempts to hangup
the
call and again local_bridgedchannel is called, and blocks while attempting
to
get the lock.  Unfortunalty sip netlock is held and everything grinds to
a
halt.

====================================================================== 

Issue History 
Date Modified    Username       Field                    Change               
====================================================================== 
2010-02-16 11:40 bzing2         New Issue                                    
2010-02-16 11:40 bzing2         Asterisk Version          => 1.6.2.2         
2010-02-16 11:40 bzing2         Regression                => No              
2010-02-16 11:40 bzing2         SVN Branch (only for SVN checkouts, not tarball
releases) => N/A             
======================================================================