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

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Message-ID: <010001671cca4b8b-2333373d-6b28-44e1-bca3-24570b8e0d2b-000000@email.amazonses.com>
Date:   Fri, 16 Nov 2018 13:51:19 +0000
From:   Christopher Lameter <cl@...ux.com>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
cc:     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 Nov 2018, Masahiro Yamada wrote:

> 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;
>  }

Ok then lets revert the initial patch whose point was to avoid a branch.
&& causes a branch again.