[asterisk-dev] Interlocking of individual channels and the channels list in chan_sip.

[David Vossel]

----- Original Message -----
> From: "Kirill Katsnelson" <kkm at adaptiveai.com>
> To: "Asterisk Developers Mailing List" <asterisk-dev at lists.digium.com>
> Sent: Thursday, June 16, 2011 2:52:23 AM
> Subject: Re: [asterisk-dev] Interlocking of individual channels and the channels list in chan_sip.
> On 110616 0041, Kirill Katsnelson wrote:
> >the rule should be to never cause an attempted
> > locking of the channels list while holding a lock on any channel.
> > Correct?
> 
> Looks like it is not even specific to chan_sip: ast_channel_lock is
> there ins ast_async_goto(). It seems that it is inherently
> deadlock-prone: call ast_async_goto() on one thread with a
> non-pbx-serviced channel, find_channel_...() on another, and there is
> a
> chance to lock. All necessary locking happens in these function.
> 
> -kkm
> 
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Ah, yes. you have identified a complex issue.  This can be resolved now that we have ref counted channels though.  We just need to make sure no channels are locked when async goto is called I believe.

-- 
David Vossel
Digium, Inc. | Software Developer, Open Source Software
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at: www.digium.com & www.asterisk.org
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