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: https://origsvn.digium.com/svn/asterisk/branches/1.4@113065 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/main/channel.c b/main/channel.c
index bef5602436f1891244f16482c00fc96e0e1514e7..bdad4413c9dd42ad1363d2fc8ed0e50b07712cec 100644 (file)
--- 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)