linux-kernel - Re: [PATCH v3 9/9] zram: use crypto decompress

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Date:	Mon, 21 Sep 2015 16:56:00 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	Joonsoo Kim <js1304@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Minchan Kim <minchan@...nel.org>,
	Nitin Gupta <ngupta@...are.org>,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
	linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>,
	Stephan Mueller <smueller@...onox.de>,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v3 9/9] zram: use crypto decompress_noctx API

On (09/18/15 14:19), Joonsoo Kim wrote:
[..]
> +	/*
> +	 * Prepare to use crypto decompress_noctx API. One tfm is required
> +	 * to initialize crypto algorithm properly and fetch corresponding
> +	 * function pointer. But, it is sharable for multiple concurrent
> +	 * decompress users.
> +	 */

if comp algorithm require zstrm for both compression and decompression,
then there seems to be no need in allocating sharable ->tfm_noctx, we
will never use it.

	-ss

> +	tfm = crypto_alloc_comp_noctx(compress, 0, 0);
> +	if (!IS_ERR(tfm))
> +		comp->tfm_noctx = tfm;
> +
>  	return comp;
>  }
> diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h
> index 4f9df8e..c76d8e4 100644
> --- a/drivers/block/zram/zcomp.h
> +++ b/drivers/block/zram/zcomp.h
> @@ -26,6 +26,7 @@ struct zcomp_strm {
>  /* dynamic per-device compression frontend */
>  struct zcomp {
>  	void *stream;
> +	struct crypto_comp *tfm_noctx;
>  	const char *backend;
>  
>  	struct zcomp_strm *(*strm_find)(struct zcomp *comp);
--
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