[PATCH] lockdep: show more details about self-test failures

Make the locking self-test failures (of 'FAILURE' type) easier to debug by
printing more information.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/debug_locks.h

@@ -24,7 +24,7 @@ extern int debug_locks_off(void);
 	int __ret = 0;							\
 									\
 	if (unlikely(c)) {						\
-		if (debug_locks_off())					\
+		if (debug_locks_silent || debug_locks_off())		\
 			WARN_ON(1);					\
 		__ret = 1;						\
 	}								\

kernel/mutex-debug.c

@@ -77,6 +77,9 @@ void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
 
 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->wait_list.prev && !lock->wait_list.next);

lib/locking-selftest.c

@@ -963,7 +963,9 @@ static void dotest(void (*testcase_fn)(void), int expected, int lockclass_mask)
 			printk("failed|");
 		} else {
 			unexpected_testcase_failures++;
+
 			printk("FAILED|");
+			dump_stack();
 		}
 	} else {
 		testcase_successes++;