[Xen-devel] [PATCH v2 RESEND] xen-netback: prefer xenbus_scanf() over xenbus_gather()

["Jan Beulich" <JBeulich@xxxxxxxx>]

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@xxxxxxxx>
---
v2: Avoid commit message to continue from subject.
---
 drivers/net/xen-netback/xenbus.c |   14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

--- 4.9-rc2/drivers/net/xen-netback/xenbus.c
+++ 4.9-rc2-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);
@@ -919,7 +919,7 @@ done:
        return 0;
 
 fail:
-       return err;
+       return err ?: -ENODATA;
 }
 
 static void connect(struct backend_info *be)



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