[tip:core/urgent] rtmutex: Avoid deadlock in rt_mutex_start_proxy_lock()
From: tip-bot for Darren Hart
Date: Wed Aug 05 2009 - 23:53:16 EST
Commit-ID: 1bbf20835c4e088667a090ce6523a0f70b62dc76
Gitweb: http://git.kernel.org/tip/1bbf20835c4e088667a090ce6523a0f70b62dc76
Author: Darren Hart <dvhltc@xxxxxxxxxx>
AuthorDate: Wed, 5 Aug 2009 12:05:21 -0700
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Thu, 6 Aug 2009 05:50:21 +0200
rtmutex: Avoid deadlock in rt_mutex_start_proxy_lock()
In the event of a lock steal or owner died,
rt_mutex_start_proxy_lock() will give the rt_mutex to the
waiting task, but it fails to release the wait_lock. This leads
to subsequent deadlocks when other tasks try to acquire the
rt_mutex.
I also removed a few extra blank lines that really spaced this
routine out. I must have been high on the \n when I wrote this
originally...
Signed-off-by: Darren Hart <dvhltc@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Dinakar Guniguntala <dino@xxxxxxxxxx>
Cc: John Stultz <johnstul@xxxxxxxxxxxxxxxxxx>
LKML-Reference: <4A79D7F1.4000405@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
kernel/rtmutex.c | 4 +---
1 files changed, 1 insertions(+), 3 deletions(-)
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
index fcd107a..29bd4ba 100644
--- a/kernel/rtmutex.c
+++ b/kernel/rtmutex.c
@@ -1039,16 +1039,14 @@ int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
if (!rt_mutex_owner(lock) || try_to_steal_lock(lock, task)) {
/* We got the lock for task. */
debug_rt_mutex_lock(lock);
-
rt_mutex_set_owner(lock, task, 0);
-
+ spin_unlock(&lock->wait_lock);
rt_mutex_deadlock_account_lock(lock, task);
return 1;
}
ret = task_blocks_on_rt_mutex(lock, waiter, task, detect_deadlock);
-
if (ret && !waiter->task) {
/*
* Reset the return value. We might have
--
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