linux-kernel - Re: [PATCH] slab: fix 'dubious: x & !y' warning from Sparse

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Message-ID: <20181116083942.GA14767@dhcp22.suse.cz>
Date:   Fri, 16 Nov 2018 09:39:42 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] slab: fix 'dubious: x & !y' warning from Sparse

On Fri 16-11-18 14:40:29, Masahiro Yamada wrote:
> Sparse reports:
> ./include/linux/slab.h:332:43: warning: dubious: x & !y

JFYI this has been discussed here http://lkml.kernel.org/r/20181105204000.129023-1-bvanassche@acm.org

> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> ---
> 
>  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 918f374..d395c73 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;
>  }
>  
>  /*
> -- 
> 2.7.4

-- 
Michal Hocko
SUSE Labs