[asterisk-dev] [Code Review] AMI module reload causes deadlock. (trunk)

[Mark Michelson]

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Ship it!


This is a lot happier "ship it!" this time. Excellent job!

- Mark


On March 19, 2012, 4:07 p.m., rmudgett wrote:
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> (Updated March 19, 2012, 4:07 p.m.)
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> 
> Review request for Asterisk Developers and Mark Michelson.
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> Summary
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> This is the trunk version of the https://reviewboard.asterisk.org/r/1818/ patch.  It fixes the concern Mark Michelson brought up about non-determinism.  Since it requires an API change to fix it, it can only be done on trunk.
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> Steps to invoke the deadlock:
> 1) Invoke an AMI Command action such as "dialplan reload" or "originate".
> 2) The command then causes an external script to request another AMI Command action.
> 3) Deadlock because the current code only allows each registered AMI action to have one active instance at a time.
> 
> This patch avoids the deadlock and tries to keep a module unload from potentially causing a crash by an active AMI action using that module.
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> This addresses bug ASTERISK-19487.
>     https://issues.asterisk.org/jira/browse/ASTERISK-19487
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> Diffs
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>   /trunk/include/asterisk/manager.h 359942 
>   /trunk/main/data.c 359942 
>   /trunk/main/db.c 359942 
>   /trunk/main/features.c 359942 
>   /trunk/main/manager.c 359942 
>   /trunk/main/pbx.c 359942 
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> Diff: https://reviewboard.asterisk.org/r/1820/diff
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> Testing
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> Code inspection says it should work and the compiler agrees. :)
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> I also loaded Asterisk to make sure it can still load because ast_manager_register_xml() can only be used on modules that are loadable.  You must use ast_manager_register_xml_core() on non-loadable modules that are part of Asterisk's core.  If you use ast_manager_register_xml() when you should use ast_manager_register_core(), you will crash on load.  If you mix them up the other way, you run the risk of crashing on unload that the additional changes on trunk are to avoid.
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> Thanks,
> 
> rmudgett
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>

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