[asterisk-bugs] [JIRA] (ASTERISK-21207) [patch] - Deadlock on fax extension calling ast_async_goto() with locked channel

[Matt Jordan (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-21207?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=204142#comment-204142 ] 

Matt Jordan commented on ASTERISK-21207:
----------------------------------------

Well, there's a first time for everything :-)

So long as you reference bump the channel prior to unlocking it, you should be relatively okay. Relative, at least, in the sense that the state of the channel may change during the indication - but that's expected, since you're about to perform an async goto on the channel (which will mangle it via the masquerade anyway). If you ref bump the channel, you guarantee that at the very least, it won't be reclaimed prior to entering the async_goto.
                
> [patch] - Deadlock on fax extension calling ast_async_goto() with locked channel
> --------------------------------------------------------------------------------
>
>                 Key: ASTERISK-21207
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-21207
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Channels/chan_dahdi, Channels/chan_sip/General
>    Affects Versions: 10.7.1, 11.2.1
>         Environment: CentOS 6.3 x86_64
>            Reporter: Ashley Winters
>            Severity: Critical
>         Attachments: fax-deadlock.patch, gdb-fax-deadlock.txt
>
>
> On an asterisk system with heavy use of AGI and inbound CNG-detected faxing, occasionally all channel activity will freeze. Running 'core show channels' returns nothing, but the logs continue running with anything except channel activity. Running with 'sip set debug on' shows that chan_sip.c doesn't even claim to be reading packets anymore.
> This deadlock was triggered several times daily across our array of asterisk servers, which process hundreds of faxes and tens of thousands of calls daily.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.asterisk.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira