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Subject: Re: [PATCH] lockdep: lockdep_depth vs. debug_locks Re: [2.6.20]
	BUG: workqueue leaked lock
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Jarek Poplawski <jarkao2@o2.pl>
Cc: Oleg Nesterov <oleg@tv-sign.ru>, Neil Brown <neilb@suse.de>,
       Andrew Morton <akpm@linux-foundation.org>,
       Folkert van Heusden <folkert@vanheusden.com>,
       linux-kernel@vger.kernel.org, "J. Bruce Fields" <bfields@fieldses.org>,
       Ingo Molnar <mingo@elte.hu>
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Date: Thu, 22 Mar 2007 08:22:37 +0100
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On Thu, 2007-03-22 at 07:11 +0100, Jarek Poplawski wrote:
> Here is some joke:
> 
> [PATCH] lockdep: lockdep_depth vs. debug_locks
> 
> lockdep really shouldn't be used when debug_locks == 0!

This happens then lockdep reports a fatal error, at which point
it will stop tracking locks and leave whatever state was there.

> Reported-by: Folkert van Heusden <folkert@vanheusden.com>
> Inspired-by: Oleg Nesterov <oleg@tv-sign.ru>
> Signed-off-by: Jarek Poplawski <jarkao2@o2.pl>

This looks sane, thanks for figuring this out.

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

> ---
> 
> diff -Nurp 2.6.21-rc4-git4-/include/linux/lockdep.h 2.6.21-rc4-git4/include/linux/lockdep.h
> --- 2.6.21-rc4-git4-/include/linux/lockdep.h	2007-03-20 20:24:17.000000000 +0100
> +++ 2.6.21-rc4-git4/include/linux/lockdep.h	2007-03-21 22:32:41.000000000 +0100
> @@ -245,7 +245,7 @@ extern void lock_release(struct lockdep_
>  
>  # define INIT_LOCKDEP				.lockdep_recursion = 0,
>  
> -#define lockdep_depth(tsk)	((tsk)->lockdep_depth)
> +#define lockdep_depth(tsk)	(debug_locks ? (tsk)->lockdep_depth : 0)
>  
>  #else /* !LOCKDEP */
>