Allow AMI action callback to be reentrant.

Fix AMI module reload deadlock regression from ASTERISK-18479 when it
tried to fix the race between calling an AMI action callback and
unregistering that action.  Refixes ASTERISK-13784 broken by
ASTERISK-17785 change.

Locking the ao2 object guaranteed that there were no active callbacks that
mattered when ast_manager_unregister() was called.  Unfortunately, this
causes the deadlock situation.  The patch stops locking the ao2 object to
allow multiple threads to invoke the callback re-entrantly.  There is no
way to guarantee a module unload will not crash because of an active
callback.  The code attempts to minimize the chance with the registered
flag and the maximum 5 second delay before ast_manager_unregister()
returns.

The trunk version of the patch changes the API to fix the race condition
correctly to prevent the module code from unloading from memory while an
action callback is active.

* Don't hold the lock while calling the AMI action callback.

(closes issue ASTERISK-19487)
Reported by: Philippe Lindheimer

Review: https://reviewboard.asterisk.org/r/1818/
Review: https://reviewboard.asterisk.org/r/1820/
........

Merged revisions 359979 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 359980 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@359981 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Richard Mudgett
2012-03-20 17:31:28 +00:00
parent 3714e8b1e5
commit 334f13d8b8
6 changed files with 91 additions and 58 deletions

View File

@@ -8193,9 +8193,9 @@ int ast_features_init(void)
if (!res)
res = ast_register_application2(parkcall, park_call_exec, NULL, NULL, NULL);
if (!res) {
ast_manager_register_xml("ParkedCalls", 0, manager_parking_status);
ast_manager_register_xml("Park", EVENT_FLAG_CALL, manager_park);
ast_manager_register_xml("Bridge", EVENT_FLAG_CALL, action_bridge);
ast_manager_register_xml_core("ParkedCalls", 0, manager_parking_status);
ast_manager_register_xml_core("Park", EVENT_FLAG_CALL, manager_park);
ast_manager_register_xml_core("Bridge", EVENT_FLAG_CALL, action_bridge);
}
res |= ast_devstate_prov_add("Park", metermaidstate);