[asterisk-dev] [Code Review] Add ability to set Max-Forwards header from dialplan, general and device configuration

[Matthew Nicholson]

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I reopened this review as I found a deadlock caused by this code.


/trunk/channels/chan_sip.c
<https://reviewboard.asterisk.org/r/778/#comment5605>

    Deadlock avoidance is needed here.  It is possible for add_header_max_forwards() to be called with the pvt locked but not the channel; pbx_builtin_getvar_helper() then attempts to lock the channel lock, which may already be held by something else waiting for the pvt lock (ast_indicate, ast_hangup, etc).  This causes a deadlock. I have seen this in the blind-transfer-accountcode test on my test box.


- Matthew


On 2010-07-13 11:29:08, Olle E Johansson wrote:
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> https://reviewboard.asterisk.org/r/778/
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> (Updated 2010-07-13 11:29:08)
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> Review request for Asterisk Developers.
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> Summary
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> This change adds the ability to set the value of the Max-Forwards header from the Asterisk dialplan and from sip.conf - the general section and per device. 
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> Diffs
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>   /trunk/channels/chan_sip.c 275912 
>   /trunk/channels/sip/include/sip.h 275912 
>   /trunk/configs/sip.conf.sample 275912 
>   /trunk/doc/tex/channelvariables.tex 275912 
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> Diff: https://reviewboard.asterisk.org/r/778/diff
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> Testing
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> The 1.4 version has been in use with the dialplan support for a few weeks. The device config is new.
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> Thanks,
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> Olle E
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