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Make some deadlock related fixes. These bugs were discovered and reported

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internally at Digium by Steve Pitts.
 - Fix up chan_local to ensure that the channel lock is held before the local
   pvt lock.
 - Don't hold the channel lock when executing the timing function, as it can
   cause a deadlock when using chan_local.  This actually changes the code back
   to be how it was before the change for issue #10765.  But, I added some other
   locking that I think will prevent the problem reported there, as well.


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@100581 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Russell Bryant
2008-01-28 17:15:41 +00:00
parent 7060a6888d
commit ef78f25e8a
3 changed files with 35 additions and 22 deletions
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37
channels/chan_local.c
View File

@@ -154,8 +154,6 @@ static int local_queue_frame(struct local_pvt *p, int isoutbound, struct ast_fra
{
struct ast_channel *other = NULL;
retrylock:
/* Recalculate outbound channel */
other = isoutbound ? p->owner : p->chan;
@@ -173,27 +171,28 @@ retrylock:
ast_clear_flag(p, LOCAL_GLARE_DETECT);
return 0;
}
if (ast_mutex_trylock(&other->lock)) {
/* Failed to lock. Release main lock and try again */
ast_mutex_unlock(&p->lock);
if (us) {
if (ast_mutex_unlock(&us->lock)) {
ast_log(LOG_WARNING, "%s wasn't locked while sending %d/%d\n",
us->name, f->frametype, f->subclass);
us = NULL;
}
ast_mutex_unlock(&p->lock);
/* Ensure that we have both channels locked */
if (us) {
while (ast_channel_trylock(other)) {
ast_channel_unlock(us);
usleep(1);
ast_channel_lock(us);
}
/* Wait just a bit */
usleep(1);
/* Only we can destroy ourselves, so we can't disappear here */
if (us)
ast_mutex_lock(&us->lock);
ast_mutex_lock(&p->lock);
goto retrylock;
} else {
ast_channel_lock(other);
}
ast_queue_frame(other, f);
ast_mutex_unlock(&other->lock);
ast_channel_unlock(other);
ast_mutex_lock(&p->lock);
ast_clear_flag(p, LOCAL_GLARE_DETECT);
return 0;
}