Re: [PATCH] - GRU Driver V3 fixes to resolve code review comments

[Nick Piggin]

On Tuesday 29 July 2008 06:05, Jack Steiner wrote:

> Index: linux/drivers/misc/sgi-gru/grutlbpurge.c
> ===================================================================
> --- linux.orig/drivers/misc/sgi-gru/grutlbpurge.c	2008-07-28
> 14:52:26.000000000 -0500 +++
> linux/drivers/misc/sgi-gru/grutlbpurge.c	2008-07-28 14:52:54.000000000
> -0500 @@ -242,7 +242,9 @@ static void gru_invalidate_range_end(str
>  	struct gru_mm_struct *gms = container_of(mn, struct gru_mm_struct,
>  						 ms_notifier);
>
> -	atomic_dec(&gms->ms_range_active);
> +	/* ..._and_test() provides needed barrier */
> +	(void)atomic_dec_and_test(&gms->ms_range_active);
> +
>  	wake_up_all(&gms->ms_wait_queue);

What about

if (atomic_dec_and_test())
    wake_up_all()
?

Also, I would prefer either a comment to say why the increment of
ms_range_active is safe, or an smp_mb__after_atomic_inc() for it too.
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