From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S933145AbcGGJkx (ORCPT <rfc822;w@1wt.eu>);
	Thu, 7 Jul 2016 05:40:53 -0400
Received: from smtp02.citrix.com ([66.165.176.63]:9947 "EHLO SMTP02.CITRIX.COM"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1756809AbcGGJkv (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Thu, 7 Jul 2016 05:40:51 -0400
X-IronPort-AV: E=Sophos;i="5.28,324,1464652800"; 
   d="scan'208";a="371739450"
Date: Thu, 7 Jul 2016 11:40:39 +0200
From: Roger Pau Monne <roger.pau@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        <xen-devel@lists.xenproject.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] xen-blkfront: prefer xenbus_scanf() over xenbus_gather()
Message-ID: <20160707094038.c3d5ebbvyj4vm73n@mac>
References: <577E297A02000078000FBF20@prv-mh.provo.novell.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="iso-8859-1"
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <577E297A02000078000FBF20@prv-mh.provo.novell.com>
User-Agent: Mutt/1.6.0-neo (2016-04-07)
X-DLP: MIA1
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, Jul 07, 2016 at 02:05:46AM -0600, Jan Beulich wrote:
> ... for single items being collected: It is more typesafe (as the
> compiler can check format string and to-be-written-to variable match)
> and requires one less parameter to be passed.
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Acked-by: Roger Pau Monné <roger.pau@citrix.com>

> ---
>  drivers/block/xen-blkfront.c |   43 +++++++++++++++++++------------------------
>  1 file changed, 19 insertions(+), 24 deletions(-)
> 
> --- 4.7-rc6-prefer-xenbus_scanf.orig/drivers/block/xen-blkfront.c
> +++ 4.7-rc6-prefer-xenbus_scanf/drivers/block/xen-blkfront.c
> @@ -2208,10 +2208,9 @@ static void blkfront_setup_discard(struc
>  		info->discard_granularity = discard_granularity;
>  		info->discard_alignment = discard_alignment;
>  	}
> -	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
> -		    "discard-secure", "%d", &discard_secure,
> -		    NULL);
> -	if (!err)
> +	err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
> +			   "discard-secure", "%u", &discard_secure);
> +	if (err > 0)

I would prefer an explicit err == 1 check (here and elsewhere), but I'm not 
going to block this patch because of that.

Roger.