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

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
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https://issues.asterisk.org/view.php?id=16840 
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Reported By:                bzing2
Assigned To:                russell
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Project:                    Asterisk
Issue ID:                   16840
Category:                   Channels/chan_local
Reproducibility:            random
Severity:                   major
Priority:                   normal
Status:                     closed
Asterisk Version:           1.6.2.2 
JIRA:                       SWP-925 
Regression:                 No 
Reviewboard Link:            
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!):  
Request Review:              
Resolution:                 fixed
Fixed in Version:           
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Date Submitted:             2010-02-16 11:40 CST
Last Modified:              2010-04-02 18:46 CDT
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Summary:                    [patch] 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.

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---------------------------------------------------------------------- 
 (0120105) svnbot (reporter) - 2010-04-02 18:46
 https://issues.asterisk.org/view.php?id=16840#c120105 
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Repository: asterisk
Revision: 256015

_U  trunk/
U   trunk/channels/chan_local.c

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r256015 | russell | 2010-04-02 18:46:46 -0500 (Fri, 02 Apr 2010) | 16
lines

Merged revisions 256014 via svnmerge from 
https://origsvn.digium.com/svn/asterisk/branches/1.4

........
  r256014 | russell | 2010-04-02 18:45:56 -0500 (Fri, 02 Apr 2010) | 9
lines
  
  Resolve a deadlock that occurs due to a pointless call to
ast_bridged_channel()
  
  (closes issue https://issues.asterisk.org/view.php?id=16840)
  Reported by: bzing2
  Patches:
        patch.txt uploaded by bzing2 (license 902)
        issue_16840.rev1.diff uploaded by russell (license 2)
  Tested by: bzing2, russell
........

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http://svn.digium.com/view/asterisk?view=rev&revision=256015 

Issue History 
Date Modified    Username       Field                    Change               
====================================================================== 
2010-04-02 18:46 svnbot         Checkin                                      
2010-04-02 18:46 svnbot         Note Added: 0120105                          
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