[asterisk-bugs] [JIRA] Commented: (ASTERISK-20437) Deadlock with ast_context_remove_extension_callerid and handle_request_do

[Michael L. Young (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-20437?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=197241#comment-197241 ] 

Michael L. Young commented on ASTERISK-20437:
---------------------------------------------

Can you reproduce this on version 1.8.16?  1.8.9.3 is really behind and there have been a lot of deadlock fixes since then based on a quick look at the changelog.

Also, I think the output of core show locks might be helpful in trying to troubleshoot this.

Debugging deadlocks: Please select DEBUG_THREADS and DONT_OPTIMIZE in the Compiler Flags section of menuselect. Recompile and install Asterisk (i.e. make install).  This will then give you the console command "core show locks." When the symptoms of the deadlock present themselves again, please provide output of the deadlock via:

# asterisk -rx "core show locks" | tee /tmp/core-show-locks.txt
# gdb -se "asterisk" <pid of asterisk> | tee /tmp/backtrace.txt 
gdb> bt
gdb> bt full
gdb> thread apply all bt

Then attach the core-show-locks.txt and backtrace.txt files to this issue. Thanks!

> Deadlock with ast_context_remove_extension_callerid and handle_request_do
> -------------------------------------------------------------------------
>
>                 Key: ASTERISK-20437
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-20437
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Channels/chan_sip/Subscriptions
>    Affects Versions: 1.8.9.3
>            Reporter: Jeff Hutchins
>         Attachments: backtrace.full.txt, backtrace.txt
>
>
> As can be seen in the attached backtrace files thread 25 obtains a sip_pvt lock (0x2aaabc46b658) at chan_sip.c:25270 (#9 in thread 25) with a call to sip_pvt_lock_full and then later in the stack trace (#5 in thread 25) tries to acquire a context lock at pbx.c:4302 with a call to ast_rdlock_context. At the same time thread 2 obtains a context lock at pbx.c:5580 (#12 in thread 2) with a call to find_context_locked(context) which in turn calls ast_rdlock_context and then later in it's stack trace thread 2 attempts to obtain a sip_pvt lock (0x2aaabc46b658) at chan_sip.c:14485 (#5 in thread 2) with a call to sip_pvt_lock_full. This naturally causes a deadlock as each thread holds the resource the other is trying to acquire. 

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