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Date: Mon, 22 Dec 2003 14:14:31 -0800
From: Andrew Morton <akpm@osdl.org>
To: Rob Love <rml@ximian.com>
Cc: joe.korty@ccur.com, wli@holomorphy.com, albert@users.sourceforge.net,
       linux-kernel@vger.kernel.org
Subject: Re: atomic copy_from_user?
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Rob Love <rml@ximian.com> wrote:
>
> Actually, dec_preempt_count() ought to call preempt_check_resched()
> itself.  In the case of !CONFIG_PREEMPT, that call would simply optimize
> away.
> 
> Attached patch is against 2.6.0.
> 
> 	Rob Love
> 
> 
>  linux/preempt.h |    1 +
>  1 files changed, 1 insertion(+)
> 
> diff -urN include/linux/preempt.h.orig include/linux/preempt.h
> --- include/linux/preempt.h.orig	2003-12-22 15:53:11.329113296 -0500
> +++ include/linux/preempt.h	2003-12-22 15:53:51.314034664 -0500
> @@ -18,6 +18,7 @@
>  #define dec_preempt_count() \
>  do { \
>  	preempt_count()--; \
> +	preempt_check_resched(); \
>  } while (0)

But preempt_enable_no_resched() calls dec_preempt_count().