[asterisk-dev] [Code Review] chan_sip, kill deadlock avoidance in do_monitor.

[David Vossel]

> On 2011-04-14 13:50:57, astmiv wrote:
> > Looks good will give it a try.
> > There are I think 2 or 3 other places in chan_sip where a loop to avoid deadlocks can be replaced by this.
> > Will test is tomorrow on my test system.

I know of the other areas you are talking about, and they are more complex since they involve two channels and a single sip pvt.  This function is not a direct replacement for those areas.  I am interested in fixing them as well though.  Perhaps I'll find time to work on that tomorrow.  Thanks for your interest in this, your patch inspired me to start looking at this again.


- David


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On 2011-04-14 11:58:51, David Vossel wrote:
> 
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> 
> (Updated 2011-04-14 11:58:51)
> 
> 
> Review request for Asterisk Developers.
> 
> 
> Summary
> -------
> 
> Deadlock avoidance between the sip pvt and the pvt->owner is very difficult.  Now that channel's are ao2 objects, this complication is no longer necessary.  It turns out the pvt's msg queue only exists because of deadlock avoidance (when deadlock avoidance fails msgs were added to a queue to be processed later), so this goes away as well.
> 
> The technique used in the new sip_lock_pvt_full() function should be used as a template for replacing all locations where deadlock avoidance occurs between a channel tech_pvt and the pvt's owner.  My hope is that this will begin a reversal of the invalid channel driver locking architecture we have been using for so long. 
> 
> 
> Diffs
> -----
> 
>   /branches/1.8/channels/chan_sip.c 313741 
> 
> Diff: https://reviewboard.asterisk.org/r/1182/diff
> 
> 
> Testing
> -------
> 
> I have tested this briefly.  It will be proven under load before being introduced into any branch.
> 
> 
> Thanks,
> 
> David
> 
>

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