locking/mutex: Fix debug_mutexes

debug_mutex_unlock() would bail when !debug_locks and forgets to
actually unlock.

Reported-by: "Michael L. Semon" <[email protected]>
Reported-by: "Kirill A. Shutemov" <[email protected]>
Reported-by: Valdis Kletnieks <[email protected]>
Fixes: 6f008e72cd11 ("locking/mutex: Fix debug checks")
Tested-by: Dave Jones <[email protected]>
Cc: Jason Low <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/kernel/locking/mutex-debug.c b/kernel/locking/mutex-debug.c
index e1191c996c59cbe3b3d2aecb7b54fd570cef17b6..5cf6731b98e9ecf1ffffa754371701613cc64bcb 100644 (file)
--- a/kernel/locking/mutex-debug.c
+++ b/kernel/locking/mutex-debug.c
@@ -71,18 +71,17 @@ void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
 
 void debug_mutex_unlock(struct mutex *lock)
 {
-       if (unlikely(!debug_locks))
-               return;
+       if (likely(debug_locks)) {
+               DEBUG_LOCKS_WARN_ON(lock->magic != lock);
 
-       DEBUG_LOCKS_WARN_ON(lock->magic != lock);
+               if (!lock->owner)
+                       DEBUG_LOCKS_WARN_ON(!lock->owner);
+               else
+                       DEBUG_LOCKS_WARN_ON(lock->owner != current);
 
-       if (!lock->owner)
-               DEBUG_LOCKS_WARN_ON(!lock->owner);
-       else
-               DEBUG_LOCKS_WARN_ON(lock->owner != current);
-
-       DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
-       mutex_clear_owner(lock);
+               DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
+               mutex_clear_owner(lock);
+       }
 
        /*
         * __mutex_slowpath_needs_to_unlock() is explicitly 0 for debug