Re: [PATCH] slab.h: Avoid using & for logical and of booleans

From: Vlastimil Babka <vbabka@suse.cz>
To: Bart Van Assche <bvanassche@acm.org>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org,
	Mel Gorman <mgorman@techsingularity.net>,
	Christoph Lameter <cl@linux.com>, Roman Gushchin <guro@fb.com>
Subject: Re: [PATCH] slab.h: Avoid using & for logical and of booleans
Date: Tue, 6 Nov 2018 09:40:09 +0100	[thread overview]
Message-ID: <b9738f05-2d9d-1489-8398-790e815294cc@suse.cz> (raw)
In-Reply-To: <20181105204000.129023-1-bvanassche@acm.org>

On 11/5/18 9:40 PM, Bart Van Assche wrote:
> This patch suppresses the following sparse warning:
> 
> ./include/linux/slab.h:332:43: warning: dubious: x & !y
> 
> Fixes: 1291523f2c1d ("mm, slab/slub: introduce kmalloc-reclaimable caches")
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Mel Gorman <mgorman@techsingularity.net>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Roman Gushchin <guro@fb.com>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>

Thanks.

Acked-by: Vlastimil Babka <vbabka@suse.cz>

> ---
>  include/linux/slab.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 918f374e7156..97d0599ddb7b 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -329,7 +329,7 @@ static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags)
>  	 * If an allocation is both __GFP_DMA and __GFP_RECLAIMABLE, return
>  	 * KMALLOC_DMA and effectively ignore __GFP_RECLAIMABLE
>  	 */
> -	return type_dma + (is_reclaimable & !is_dma) * KMALLOC_RECLAIM;
> +	return type_dma + is_reclaimable * !is_dma * KMALLOC_RECLAIM;
>  }
>  
>  /*
> 