This fix prevents a deadlock that was experienced in chan_local. There was

deadlock prevention in place in chan_local, but it would not work in a specific
case because the channel was recursively locked. By unlocking the channel prior
to calling the generator's generate callback in ast_read_generator_actions(), we
prevent the recursive locking, and therefore the deadlock.

(closes issue #12307)
Reported by: callguy
Patches:
      12307.patch uploaded by putnopvut (license 60)
Tested by: callguy



git-svn-id: http://svn.digium.com/svn/asterisk/branches/1.4@113065 f38db490-d61c-443f-a65b-d21fe96a405b

1 files changed, 10 insertions, 0 deletions

diff --git a/main/channel.c b/main/channel.c
index bef560243..bdad4413c 100644
--- a/main/channel.c
+++ b/main/channel.c
@@ -1896,7 +1896,17 @@ static void ast_read_generator_actions(struct ast_channel *chan, struct ast_fram
 		}
 
 		chan->generatordata = NULL;     /* reset, to let writes go through */
+		/* This unlock is here based on two assumptions that hold true at this point in the
+		 * code. 1) this function is only called from within __ast_read() and 2) all generators
+		 * call ast_write() in their generate callback.
+		 *
+		 * The reason this is added is so that when ast_write is called, the lock that occurs 
+		 * there will not recursively lock the channel. Doing this will cause intended deadlock 
+		 * avoidance not to work in deeper functions
+		 */
+		ast_channel_unlock(chan);
 		res = chan->generator->generate(chan, tmp, f->datalen, f->samples);
+		ast_channel_lock(chan);
 		chan->generatordata = tmp;
 		if (res) {
 			if (option_debug > 1)