linux-kernel - [PATCH] mutex-debug: Check mutex magic before owner

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Date:	Wed, 23 Apr 2008 15:38:12 +1000
From:	Jeremy Kerr <jk@...abs.org>
To:	<linux-kernel@...r.kernel.org>
Cc:	<mingo@...hat.com>
Subject: [PATCH] mutex-debug: Check mutex magic before owner

Currently, the mutex debug code checks the lock->owner before
lock->magic, so a corrupt mutex will most likely result in
failing the owner check, rather than the magic check.

This change to debug_mutex_unlock does the magic check first, so
we have a better idea of what breaks.

Signed-off-by: Jeremy Kerr <jk@...abs.org>

---
 kernel/mutex-debug.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/mutex-debug.c b/kernel/mutex-debug.c
index 3aaa06c..1d94160 100644
--- a/kernel/mutex-debug.c
+++ b/kernel/mutex-debug.c
@@ -79,8 +79,8 @@ void debug_mutex_unlock(struct mutex *lock)
 	if (unlikely(!debug_locks))
 		return;
 
-	DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
 	DEBUG_LOCKS_WARN_ON(lock->magic != lock);
+	DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
 	DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
 	DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
 }
--
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