From patchwork Fri Jul 8 12:28:58 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Beulich X-Patchwork-Id: 9220789 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id C2E5460467 for ; Fri, 8 Jul 2016 12:31:11 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B35CE2875E for ; Fri, 8 Jul 2016 12:31:11 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A788828760; Fri, 8 Jul 2016 12:31:11 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 94DC82875E for ; Fri, 8 Jul 2016 12:31:10 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bLUtz-0006dA-DE; Fri, 08 Jul 2016 12:29:03 +0000 Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bLUtx-0006cz-Sk for xen-devel@lists.xenproject.org; Fri, 08 Jul 2016 12:29:01 +0000 Received: from [193.109.254.147] by server-3.bemta-14.messagelabs.com id A5/FE-17627-D8C9F775; Fri, 08 Jul 2016 12:29:01 +0000 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrKIsWRWlGSWpSXmKPExsXS6fjDS7dnTn2 4Qe8qOYvvWyYzOTB6HP5whSWAMYo1My8pvyKBNWPTTt2CPu6KYw9eMzYwzufsYuTkEBLIk2i/ 2csOYvMK2En8O3+NFcSWEDCU2Dd/FRuIzSKgKjF72SwWEJtNQF2i7dl2sBoRAWWJu99nAMW5O JgFZjNKNH1ZyQiSEBYIkNixbT4jxAI7iXOHN4Mt4BSwlzjy8BdTFyMH0DJBib87hEHCzAJaEg 9/3WKBsLUlli18zQxSwiwgLbH8H8cERr5ZCA2zkDTMQtIwC6FhASPLKkaN4tSistQiXSMLvaS izPSMktzEzBxdQ0MTvdzU4uLE9NScxKRiveT83E2MwOCrZ2Bg3MG47rjfIUZJDiYlUV7DgPpw Ib6k/JTKjMTijPii0pzU4kOMMhwcShK8b2cD5QSLUtNTK9Iyc4BxAJOW4OBREuHtBUnzFhck5 hZnpkOkTjEqSonzLgVJCIAkMkrz4NpgsXeJUVZKmJeRgYFBiKcgtSg3swRV/hWjOAejkjDvFJ ApPJl5JXDTXwEtZgJabBAAtrgkESEl1cBYfv0H+2XHTRXO0zyWTDt/U8GH07O67X+k6+aNy5+ JNgpO42P9bRaTP2MNUxLHHr8505WMP7XH160VVf2hstvb1a2CebrZ4XNlleUPNvQzJIRXnX5h vsHhoKB2//p9/J+aXLv2TNoXMvn5L6fNAgZGU987pF566Vtyre6i2eL9jl5Zm/4sLWxSYinOS DTUYi4qTgQA/LQL+rgCAAA= X-Env-Sender: JBeulich@suse.com X-Msg-Ref: server-3.tower-27.messagelabs.com!1467980937!52346067!1 X-Originating-IP: [137.65.248.74] X-SpamReason: No, hits=0.0 required=7.0 tests= X-StarScan-Received: X-StarScan-Version: 8.77; banners=-,-,- X-VirusChecked: Checked Received: (qmail 63035 invoked from network); 8 Jul 2016 12:28:59 -0000 Received: from prv-mh.provo.novell.com (HELO prv-mh.provo.novell.com) (137.65.248.74) by server-3.tower-27.messagelabs.com with DHE-RSA-AES256-GCM-SHA384 encrypted SMTP; 8 Jul 2016 12:28:59 -0000 Received: from INET-PRV-MTA by prv-mh.provo.novell.com with Novell_GroupWise; Fri, 08 Jul 2016 06:28:57 -0600 Message-Id: <577FB8AA02000078000FCA21@prv-mh.provo.novell.com> X-Mailer: Novell GroupWise Internet Agent 14.2.0 Date: Fri, 08 Jul 2016 06:28:58 -0600 From: "Jan Beulich" To: "Wei Liu" References: <577FB70002000078000FC9FA@prv-mh.provo.novell.com> In-Reply-To: <577FB70002000078000FC9FA@prv-mh.provo.novell.com> Mime-Version: 1.0 Content-Disposition: inline Cc: Juergen Gross , xen-devel@lists.xenproject.org, boris.ostrovsky@oracle.com, david.vrabel@citrix.com, netdev@vger.kernel.org Subject: [Xen-devel] [PATCH v2 4/4] xen-netback: prefer xenbus_scanf() over xenbus_gather() X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP 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: Wei Liu --- v2: Avoid commit message to continue from subject. --- drivers/net/xen-netback/xenbus.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) --- 4.7-rc6-prefer-xenbus_scanf.orig/drivers/net/xen-netback/xenbus.c +++ 4.7-rc6-prefer-xenbus_scanf/drivers/net/xen-netback/xenbus.c @@ -842,16 +842,16 @@ static int connect_ctrl_ring(struct back unsigned int evtchn; int err; - err = xenbus_gather(XBT_NIL, dev->otherend, - "ctrl-ring-ref", "%u", &val, NULL); - if (err) + err = xenbus_scanf(XBT_NIL, dev->otherend, + "ctrl-ring-ref", "%u", &val); + if (err <= 0) goto done; /* The frontend does not have a control ring */ ring_ref = val; - err = xenbus_gather(XBT_NIL, dev->otherend, - "event-channel-ctrl", "%u", &val, NULL); - if (err) { + err = xenbus_scanf(XBT_NIL, dev->otherend, + "event-channel-ctrl", "%u", &val); + if (err <= 0) { xenbus_dev_fatal(dev, err, "reading %s/event-channel-ctrl", dev->otherend); @@ -872,7 +872,7 @@ done: return 0; fail: - return err; + return err ?: -ENODATA; } static void connect(struct backend_info *be)