linux-kernel - [patch] lock debugging: fix DEBUG_LOCKS_WARN_ON() & debug_locks

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Message-ID: <20061216080458.GC16116@elte.hu>
Date:	Sat, 16 Dec 2006 09:04:58 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Matthew Wilcox <matthew@....cx>
Cc:	linux-kernel@...r.kernel.org, Andrew Morton <akpm@...l.org>
Subject: [patch] lock debugging: fix DEBUG_LOCKS_WARN_ON() & debug_locks_silent


* Matthew Wilcox <matthew@....cx> wrote:

> Moreover, do we want to get stack dumps while running the locking 
> testsuite in the first place?  From various comments, it looks like 
> it's supposed to be turned off, but it looks like the sense of 
> debug_locks_silent is inverted in the definition of 
> DEBUG_LOCKS_WARN_ON:
> 
>         if (unlikely(c)) {                                              \
>                 if (debug_locks_silent || debug_locks_off())            \
>                         WARN_ON(1);                                     \
> 
> Surely that should be:
> 
> 		if (!debug_locks_silent && debug_locks_off())
> 			WARN_ON(1);

oops, indeed! Fix below.

	Ingo

------------->
Subject: [patch] lock debugging: fix DEBUG_LOCKS_WARN_ON() & debug_locks_silent
From: Ingo Molnar <mingo@...e.hu>

Matthew Wilcox noticed that the debug_locks_silent use should be
inverted in DEBUG_LOCKS_WARN_ON(). This bug was causing spurious
stacktraces and incorrect failures in the locking self-test on the
parisc kernel.

Bug-found-by: Matthew Wilcox <matthew@....cx>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 include/linux/debug_locks.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux/include/linux/debug_locks.h
===================================================================
--- linux.orig/include/linux/debug_locks.h
+++ linux/include/linux/debug_locks.h
@@ -24,7 +24,7 @@ extern int debug_locks_off(void);
 	int __ret = 0;							\
 									\
 	if (unlikely(c)) {						\
-		if (debug_locks_silent || debug_locks_off())		\
+		if (!debug_locks_silent && debug_locks_off())		\
 			WARN_ON(1);					\
 		__ret = 1;						\
 	}								\
-
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