From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755127AbcGHM01 (ORCPT ); Fri, 8 Jul 2016 08:26:27 -0400 Received: from prv-mh.provo.novell.com ([137.65.248.74]:57562 "EHLO prv-mh.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754848AbcGHM0W (ORCPT ); Fri, 8 Jul 2016 08:26:22 -0400 Message-Id: <577FB80E02000078000FCA1B@prv-mh.provo.novell.com> X-Mailer: Novell GroupWise Internet Agent 14.2.0 Date: Fri, 08 Jul 2016 06:26:22 -0600 From: "Jan Beulich" To: "Roger Pau Monne" , "Konrad Rzeszutek Wilk" Cc: , , , "Juergen Gross" , Subject: [PATCH v2 2/4] xen-blkback: prefer xenbus_scanf() over xenbus_gather() References: <577FB70002000078000FC9FA@prv-mh.provo.novell.com> In-Reply-To: <577FB70002000078000FC9FA@prv-mh.provo.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For single items being collected this should be preferred as being more typesafe (as the compiler can check format string and to-be-written-to variable match) and more efficient (requiring one less parameter to be passed). Signed-off-by: Jan Beulich Acked-by: Roger Pau Monné --- v2: Avoid commit message to continue from subject. --- drivers/block/xen-blkback/xenbus.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) --- 4.7-rc6-prefer-xenbus_scanf.orig/drivers/block/xen-blkback/xenbus.c +++ 4.7-rc6-prefer-xenbus_scanf/drivers/block/xen-blkback/xenbus.c @@ -1022,9 +1022,9 @@ static int connect_ring(struct backend_i pr_debug("%s %s\n", __func__, dev->otherend); be->blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT; - err = xenbus_gather(XBT_NIL, dev->otherend, "protocol", - "%63s", protocol, NULL); - if (err) + err = xenbus_scanf(XBT_NIL, dev->otherend, "protocol", + "%63s", protocol); + if (err <= 0) strcpy(protocol, "unspecified, assuming default"); else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE)) be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE; @@ -1036,10 +1036,9 @@ static int connect_ring(struct backend_i xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol); return -ENOSYS; } - err = xenbus_gather(XBT_NIL, dev->otherend, - "feature-persistent", "%u", - &pers_grants, NULL); - if (err) + err = xenbus_scanf(XBT_NIL, dev->otherend, + "feature-persistent", "%u", &pers_grants); + if (err <= 0) pers_grants = 0; be->blkif->vbd.feature_gnt_persistent = pers_grants;