From 30910d48bc2f839105e08acf04463e53929ed38a Mon Sep 17 00:00:00 2001
From: Mark Spencer <markster@digium.com>
Date: Tue, 29 Jun 2004 10:51:00 +0000
Subject: [PATCH] Avoid potential deadlocks in channel_walk_locked, and detect
serious failures
git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@3340 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---
channel.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
diff --git a/channel.c b/channel.c
index 8738777057..510e0c0d12 100755
--- a/channel.c
+++ b/channel.c
@@ -452,6 +452,8 @@ struct ast_channel *ast_channel_walk_locked(struct ast_channel *prev)
{
/* Returns next channel (locked) */
struct ast_channel *l, *ret=NULL;
+ int retries = 0;
+retry:
ast_mutex_lock(&chlock);
l = channels;
if (!prev) {
@@ -465,8 +467,21 @@ struct ast_channel *ast_channel_walk_locked(struct ast_channel *prev)
ret = l->next;
l = l->next;
}
- if (ret)
- ast_mutex_lock(&ret->lock);
+ if (ret) {
+ if (ast_mutex_trylock(&ret->lock)) {
+ if (retries < 10)
+ ast_log(LOG_DEBUG, "Avoiding deadlock for '%s'\n", ret->name);
+ else
+ ast_log(LOG_WARNING, "Avoided deadlock for '%s', %d retries!\n", ret->name, retries);
+ ast_mutex_unlock(&chlock);
+ if (retries < 10) {
+ usleep(1);
+ retries++;
+ goto retry;
+ } else
+ return NULL;
+ }
+ }
ast_mutex_unlock(&chlock);
return ret;
--
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