Re: [PATCH] lock assertion macros for 2.5.30

From: Rik van Riel (riel@conectiva.com.br)
Date: Wed Aug 07 2002 - 16:02:19 EST

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On Wed, 7 Aug 2002, Jesse Barnes wrote:

> +++ linux-2.5.30-lockassert/drivers/scsi/scsi.c Wed Aug 7 11:35:32 2002
> @@ -262,7 +262,7 @@

> + MUST_NOT_HOLD(q->queue_lock);

...

> +#if defined(CONFIG_DEBUG_SPINLOCK) && defined(CONFIG_SMP)
> +#define MUST_HOLD(lock) BUG_ON(!spin_is_locked(lock))
> +#define MUST_NOT_HOLD(lock) BUG_ON(spin_is_locked(lock))

Please tell me the MUST_NOT_HOLD thing is a joke.

What is to prevent another CPU in another code path
from holding this spinlock when the code you've
inserted the MUST_NOT_HOLD in is on its merry way
not holding the lock ?

regards,

Rik

-- Bravely reimplemented by the knights who say "NIH".

http://www.surriel.com/ http://distro.conectiva.com/

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