Merged revisions 77887 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.4

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r77887 | russell | 2007-08-01 17:16:17 -0500 (Wed, 01 Aug 2007) | 23 lines

Fix some race conditions which have been causing weird problems in chan_iax2.
The most notable problem is that people have been seeing storms of VNAK frames
being sent due to really old frames mysteriously being in the retransmission
queue and never getting removed.

It was possible that a dynamic thread got created, but did not acquire its lock
before the thread that created it signals it to perform an action.  When this
happens, the thread will sleep until it hits a timeout, and then get destroyed.
So, the action never gets performed and in some cases, means a frame doesn't
get transmitted and never gets freed since the scheduler never gets a chance
to reschedule transmission.

Another less severe race condition is in the handling of a timeout for a dynamic
thread.  It was possible for it to be acquired to perform at action at the same
time that it hit a timeout.  When this occurs, whatever action it was acquired
for would never get performed.

(patch contributed by Mihai and SteveK)
(closes issue #10289)
(closes issue #10248)
(closes issue #10232)
(possibly related to issue #10359)

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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@77889 65c4cc65-6c06-0410-ace0-fbb531ad65f3