| Message ID | 582190C1020000780011CF5C@prv-mh.provo.novell.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> -----Original Message----- > From: Jan Beulich [mailto:JBeulich@suse.com] > Sent: 08 November 2016 07:46 > To: Paul Durrant <Paul.Durrant@citrix.com>; Wei Liu <wei.liu2@citrix.com> > Cc: xen-devel <xen-devel@lists.xenproject.org>; 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 <jbeulich@suse.com> LGTM Reviewed-by: Paul Durrant <paul.durrant@citrix.com> > --- > 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); > >
From: "Jan Beulich" <JBeulich@suse.com> Date: Tue, 08 Nov 2016 00:45:53 -0700 > 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 <jbeulich@suse.com> > --- > 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. Applied to net-next, thanks.
--- 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);
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 <jbeulich@suse.com> --- 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(-)