[asterisk-bugs] [Asterisk 0017216]: [patch] Deadlock between ast_hangup and pri_dchannel

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
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https://issues.asterisk.org/view.php?id=17216 
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Reported By:                lmsteffan
Assigned To:                jpeeler
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Project:                    Asterisk
Issue ID:                   17216
Category:                   Channels/chan_dahdi
Reproducibility:            random
Severity:                   major
Priority:                   normal
Status:                     acknowledged
Target Version:             1.6.2.9
Asterisk Version:           SVN 
JIRA:                       SWP-1328 
Regression:                 No 
Reviewboard Link:            
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!): 236802 
Request Review:              
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Date Submitted:             2010-04-20 19:49 CDT
Last Modified:              2010-05-07 10:33 CDT
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Summary:                    [patch] Deadlock between ast_hangup and pri_dchannel
Description: 
I think what causes the deadlock is the following :

Ast_hangup performs a lock of the channel then, through dahdi_hangup,
tries to lock the private (Dahdi) part of the channel.

Meanwhile, pri_dchannel first seizes the private part of the channel,
then, in ast_softhangup_nolock, tries to lock the channel that owns this
private part.

A deadlock occurs as both threads attempt to seize both deadlocks in
reverse order.

I include a full trace and a snapshot of the locks.


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 (0121550) svnbot (reporter) - 2010-05-07 10:33
 https://issues.asterisk.org/view.php?id=17216#c121550 
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Repository: asterisk
Revision: 261866

U   trunk/channels/sig_pri.c

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r261866 | jpeeler | 2010-05-07 10:33:52 -0500 (Fri, 07 May 2010) | 14
lines

Fix deadlock in sig_pri when hanging up.

The pri_dchannel thread currently violates locking order by locking the
private
and then attempting to queue a frame, which needs to lock the channel.
Queueing
a frame is unneccesary though and is actually a regression since sig_pri.
All the places that currently use ast_softhangup_nolock now will just set
the
softhangup value directly as before.

(closes issue https://issues.asterisk.org/view.php?id=17216)
Reported by: lmsteffan
Patches: 
      bug17216.patch uploaded by jpeeler (license 325)


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http://svn.digium.com/view/asterisk?view=rev&revision=261866 

Issue History 
Date Modified    Username       Field                    Change               
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2010-05-07 10:33 svnbot         Note Added: 0121550                          
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