From: Jeremy Kerr <jk@ozlabs.org>
Date: Wed, 14 May 2008 23:22:58 +0000 (-0700)
Subject: mutex-debug: check mutex magic before owner
X-Git-Tag: v2.6.27-rc1~1100^2~8
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=493d35863dbb692c38c1415fd83d88dfb902ae37;p=linux-2.6

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@ozlabs.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

diff --git a/kernel/mutex-debug.c b/kernel/mutex-debug.c
index 3aaa06c561..1d94160eb5 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());
 }