[asterisk-dev] [Code Review] Fix potential deadlock between masquerade and chan_local.

[Mark Michelson]

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Ship it!


Go for it!


/branches/1.8/main/channel.c
<https://reviewboard.asterisk.org/r/1915/#comment11918>

    Hm, the comment says "original original's" but then the clonechan is hung up. Even if the wording on the comment was intentional, ast_do_masquerade() is the last place where confusing comments are needed.


- Mark


On May 11, 2012, 12:05 p.m., rmudgett wrote:
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> (Updated May 11, 2012, 12:05 p.m.)
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> 
> Review request for Asterisk Developers.
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> Summary
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> ast_do_masquerade() calls ast_indicate() with the channel lock held.  This is a deadlock waiting to happen if the channel involved is a local channel.
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> * Restructure ast_do_masquerade() to not hold channel locks while it calls ast_indicate().
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> * Simplify many calls to ast_do_masquerade() since it will never return a failure now.  If it does fail internally because a channel driver callback operation failed, the only thing ast_do_masquerade() can do is generate a warning message about strange things may happen and press on.
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> * Fixed the call to ast_bridged_channel() in ast_do_masquerade().  This change fixes half of the deadlock reported in ASTERISK-19801 between masquerades and chan_iax.
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> This addresses bugs ASTERISK-19537 and ASTERISK-19801.
>     https://issues.asterisk.org/jira/browse/ASTERISK-19537
>     https://issues.asterisk.org/jira/browse/ASTERISK-19801
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> 
> Diffs
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>   /branches/1.8/main/channel.c 366290 
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> Diff: https://reviewboard.asterisk.org/r/1915/diff
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> Testing
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> A manual version of the yet to be written external test in ASTERISK-19807 passes.  I tested this patch with a call having a chain of 300 local channel pairs that optimize themselves out of the call.  It takes a minute for the local channels to get optimized out but once they are gone the call passes audio.
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> Thanks,
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> rmudgett
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>

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