bridge: Unlock channel during Local peer check.

It's not safe to keep the channel locked while locking
the peer Local channel, as it can result in a deadlock.

This change unlocks it during this time but keeps the
bridge locked to ensure nothing changes about the bridge.

ASTERISK-29821

Change-Id: Ib68eb7037e5a479bcc2aceee77337cdde1fbdde6

main/bridge_channel.c

@@ -2861,11 +2861,13 @@ int bridge_channel_internal_join(struct ast_bridge_channel *bridge_channel)
 	ast_bridge_lock(bridge_channel->bridge);
 
 	ast_channel_lock(bridge_channel->chan);
-
 	peer = ast_local_get_peer(bridge_channel->chan);
+
 	if (peer) {
 		struct ast_bridge *peer_bridge;
 
+		ast_channel_unlock(bridge_channel->chan);
+
 		ast_channel_lock(peer);
 		peer_bridge = ast_channel_internal_bridge(peer);
 		ast_channel_unlock(peer);
@@ -2875,14 +2877,15 @@ int bridge_channel_internal_join(struct ast_bridge_channel *bridge_channel)
 		 * to be reference counted or locked.
 		 */
 		if (peer_bridge == bridge_channel->bridge) {
-			ast_channel_unlock(bridge_channel->chan);
 			ast_bridge_unlock(bridge_channel->bridge);
 			ast_debug(1, "Bridge %s: %p(%s) denying Bridge join to prevent Local channel loop\n",
 				bridge_channel->bridge->uniqueid,
 				bridge_channel,
 				ast_channel_name(bridge_channel->chan));
 			return -1;
 		}
+
+		ast_channel_lock(bridge_channel->chan);
 	}
 
 	bridge_channel->read_format = ao2_bump(ast_channel_readformat(bridge_channel->chan));