Index: channels/chan_zap.c
===================================================================
--- channels/chan_zap.c	(revision 121854)
+++ channels/chan_zap.c	(working copy)
@@ -4631,9 +4631,10 @@
 	void *readbuf;
 	struct ast_frame *f;
 	
+	while (ast_mutex_trylock(&p->lock)) {
+		DEADLOCK_AVOIDANCE(&ast->lock);
+	}
 
-	ast_mutex_lock(&p->lock);
-	
 	index = zt_get_index(ast, p, 0);
 	
 	/* Hang up if we don't really exist */