From: Russell Bryant <russell@russellbryant.com>
Date: Fri, 5 Oct 2007 16:44:21 +0000 (+0000)
Subject: Do deadlock avoidance in a couple more places.  You can't lock two channels
X-Git-Tag: 1.4.13~21
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=21d9b7996ba79cf65a7be32348f8ac293d59e0a3;p=thirdparty%2Fasterisk.git

Do deadlock avoidance in a couple more places.  You can't lock two channels
at the same time without doing extra work to make sure it succeeds.
(closes issue #10895, patch by me)


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@84783 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---

diff --git a/channels/chan_zap.c b/channels/chan_zap.c
index f490c047ad..90dae43453 100644
--- a/channels/chan_zap.c
+++ b/channels/chan_zap.c
@@ -3167,7 +3167,11 @@ static enum ast_bridge_result zt_bridge(struct ast_channel *c0, struct ast_chann
 		return AST_BRIDGE_FAILED_NOWARN;
 
 	ast_mutex_lock(&c0->lock);
-	ast_mutex_lock(&c1->lock);
+	while (ast_mutex_trylock(&c1->lock)) {
+		ast_mutex_unlock(&c0->lock);
+		usleep(1);
+		ast_mutex_lock(&c0->lock);
+	}
 
 	p0 = c0->tech_pvt;
 	p1 = c1->tech_pvt;
@@ -3335,7 +3339,12 @@ static enum ast_bridge_result zt_bridge(struct ast_channel *c0, struct ast_chann
 		/* Here's our main loop...  Start by locking things, looking for private parts, 
 		   and then balking if anything is wrong */
 		ast_mutex_lock(&c0->lock);
-		ast_mutex_lock(&c1->lock);
+		while (ast_mutex_trylock(&c1->lock)) {
+			ast_mutex_unlock(&c0->lock);
+			usleep(1);
+			ast_mutex_lock(&c0->lock);
+		}
+
 		p0 = c0->tech_pvt;
 		p1 = c1->tech_pvt;