From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Durrant Subject: RE: [PATCH v3] xen-netback: prefer xenbus_scanf() over xenbus_gather() Date: Tue, 8 Nov 2016 09:37:34 +0000 Message-ID: References: <582190C1020000780011CF5C@prv-mh.provo.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Cc: xen-devel , "netdev@vger.kernel.org" To: Jan Beulich , Wei Liu Return-path: Received: from smtp.eu.citrix.com ([185.25.65.24]:19206 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933076AbcKHJhg (ORCPT ); Tue, 8 Nov 2016 04:37:36 -0500 In-Reply-To: <582190C1020000780011CF5C@prv-mh.provo.novell.com> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: > -----Original Message----- > From: Jan Beulich [mailto:JBeulich@suse.com] > Sent: 08 November 2016 07:46 > To: Paul Durrant ; Wei Liu > Cc: xen-devel ; netdev@vger.kernel.org > Subject: [PATCH v3] xen-netback: prefer xenbus_scanf() over > xenbus_gather() > > 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 LGTM Reviewed-by: Paul Durrant > --- > v3: For consistency with other code don't consider zero an error > (utilizing that xenbus_scanf() at present won't return zero). > v2: Avoid commit message to continue from subject. > --- > drivers/net/xen-netback/xenbus.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > --- 4.9-rc4/drivers/net/xen-netback/xenbus.c > +++ 4.9-rc4-xen-netback-prefer-xenbus_scanf/drivers/net/xen- > netback/xenbus.c > @@ -889,16 +889,16 @@ 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); > >