[Xen-devel] [PATCH v2 2/4] xen-blkback: 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>
Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
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;



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