[asterisk-dev] [Code Review] app_directed_pickup Implement the ability to remove a channel group on bridged channel

[Alec Davis]

> On 2011-05-26 12:00:55, rmudgett wrote:
> > /trunk/main/channel.c, lines 6445-6450
> > <https://reviewboard.asterisk.org/r/1118/diff/7/?file=16740#file16740line6445>
> >
> >     The defined locking order is the channels container then the channel.  This is not the correct way to fix the deadlock.
> 
> rmudgett wrote:
>     Is the original deadlock still possible?
> 
> irroot wrote:
>     i will put a log message on if you want and try catch it ...
>     
>     i have seen this regualarly under the following circumstances 
>     ring all group 5+ phones not attended in evenings simultaneous pickups triggered ...
>     
>      ast_channel_masquerade is called with channel locked it should not be ... 
>     
>     /*!
>      * \brief Masquerade a channel
>      *
>      * \note Assumes _NO_ channels and _NO_ channel pvt's are locked.  If a channel is locked while calling
>      *       this function, it invalidates our channel container locking order.  All channels
>      *       must be unlocked before it is permissible to lock the channels' ao2 container.
>      */
>     
>     now with ao2_callback_find locking and unlocking channels and channels this deadlock is possible AFAIK
>     
>     the recent changes did not sort out this possible problem due to it been locked going in...

The actual ast_do_masquerade has the requirements that nothing is locked.

But ast_channel_masquerade(), that prepares for the masquerade doesn't.


- Alec


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On 2011-05-26 13:32:29, irroot wrote:
> 
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> 
> (Updated 2011-05-26 13:32:29)
> 
> 
> Review request for Asterisk Developers.
> 
> 
> Summary
> -------
> 
> as a companion to 0018825 to aid with the move from call-limits to channel group variables. the problem with pickup and queue is that they manage channels outside the dialplan and need "helpers" to deal with channel groups.
> 
> in the case of pickup when a call is placed to a extension with say a "<EXTEN>@called" channel group when it is picked up this needs to be cleared to allow further calls when call waiting is disabled.
> 
> exten => s,n,GotoIf($[$[${ GROUP_COUNT(${ARG1}@called)} >= 1] | $[${GROUP_COUNT(${ARG1}@caller)} >= 1] | $[${GROUP_COUNT(${ARG1}@pickup)} >= 1] | $[${GROUP_COUNT(${ARG1}@qagent)} >= 1]]?s-BUSY,1)
> 
> where
> caller is set when a call is placed.
> called is set when a call is received
> pickup is set when before calling pickup in the dialplan
> qagent is set with patch to queue
> 
> Hope this is found to be useful and finds a home in trunk. 
> 
> not sure what time to put in the "wait for bridge" perhaps there is a better method ?? 
> 
> 
> This addresses bug 18830.
>     https://issues.asterisk.org/view.php?id=18830
> 
> 
> Diffs
> -----
> 
>   /trunk/main/channel.c 320937 
> 
> Diff: https://reviewboard.asterisk.org/r/1118/diff
> 
> 
> Testing
> -------
> 
> 
> Thanks,
> 
> irroot
> 
>

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