xen: make use of xenbus_read_unsigned() in xen-netback

Use xenbus_read_unsigned() instead of xenbus_scanf() when possible.
This requires to change the type of some reads from int to unsigned,
but these cases have been wrong before: negative values are not allowed
for the modified cases.

Cc: wei.liu2@citrix.com
Cc: paul.durrant@citrix.com
Cc: netdev@vger.kernel.org

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: David Vrabel <david.vrabel@citrix.com>

1 files changed, 14 insertions, 36 deletions

diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 8674e188b697..7356e00fac54 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -785,12 +785,9 @@ static void xen_mcast_ctrl_changed(struct xenbus_watch *watch,
         struct xenvif *vif = container_of(watch, struct xenvif,
                                           mcast_ctrl_watch);
         struct xenbus_device *dev = xenvif_to_xenbus_device(vif);
-        int val;
 
-        if (xenbus_scanf(XBT_NIL, dev->otherend,
-                         "request-multicast-control", "%d", &val) < 0)
-                val = 0;
-        vif->multicast_control = !!val;
+        vif->multicast_control = !!xenbus_read_unsigned(dev->otherend,
+                                        "request-multicast-control", 0);
 }
 
 static int xen_register_mcast_ctrl_watch(struct xenbus_device *dev,
@@ -934,12 +931,9 @@ static void connect(struct backend_info *be)
         /* Check whether the frontend requested multiple queues
          * and read the number requested.
          */
-        err = xenbus_scanf(XBT_NIL, dev->otherend,
-                           "multi-queue-num-queues",
-                           "%u", &requested_num_queues);
-        if (err < 0) {
-                requested_num_queues = 1; /* Fall back to single queue */
-        } else if (requested_num_queues > xenvif_max_queues) {
+        requested_num_queues = xenbus_read_unsigned(dev->otherend,
+                                        "multi-queue-num-queues", 1);
+        if (requested_num_queues > xenvif_max_queues) {
                 /* buggy or malicious guest */
                 xenbus_dev_fatal(dev, err,
                                  "guest requested %u queues, exceeding the maximum of %u.",
@@ -1134,7 +1128,7 @@ static int read_xenbus_vif_flags(struct backend_info *be)
         struct xenvif *vif = be->vif;
         struct xenbus_device *dev = be->dev;
         unsigned int rx_copy;
-        int err, val;
+        int err;
 
         err = xenbus_scanf(XBT_NIL, dev->otherend, "request-rx-copy", "%u",
                            &rx_copy);
@@ -1150,10 +1144,7 @@ static int read_xenbus_vif_flags(struct backend_info *be)
         if (!rx_copy)
                 return -EOPNOTSUPP;
 
-        if (xenbus_scanf(XBT_NIL, dev->otherend,
-                         "feature-rx-notify", "%d", &val) < 0)
-                val = 0;
-        if (!val) {
+        if (!xenbus_read_unsigned(dev->otherend, "feature-rx-notify", 0)) {
                 /* - Reduce drain timeout to poll more frequently for
                  *   Rx requests.
                  * - Disable Rx stall detection.
@@ -1162,34 +1153,21 @@ static int read_xenbus_vif_flags(struct backend_info *be)
                 be->vif->stall_timeout = 0;
         }
 
-        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg",
-                         "%d", &val) < 0)
-                val = 0;
-        vif->can_sg = !!val;
+        vif->can_sg = !!xenbus_read_unsigned(dev->otherend, "feature-sg", 0);
 
         vif->gso_mask = 0;
 
-        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4",
-                         "%d", &val) < 0)
-                val = 0;
-        if (val)
+        if (xenbus_read_unsigned(dev->otherend, "feature-gso-tcpv4", 0))
                 vif->gso_mask |= GSO_BIT(TCPV4);
 
-        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6",
-                         "%d", &val) < 0)
-                val = 0;
-        if (val)
+        if (xenbus_read_unsigned(dev->otherend, "feature-gso-tcpv6", 0))
                 vif->gso_mask |= GSO_BIT(TCPV6);
 
-        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
-                         "%d", &val) < 0)
-                val = 0;
-        vif->ip_csum = !val;
+        vif->ip_csum = !xenbus_read_unsigned(dev->otherend,
+                                             "feature-no-csum-offload", 0);
 
-        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-ipv6-csum-offload",
-                         "%d", &val) < 0)
-                val = 0;
-        vif->ipv6_csum = !!val;
+        vif->ipv6_csum = !!xenbus_read_unsigned(dev->otherend,
+                                                "feature-ipv6-csum-offload", 0);
 
         return 0;
 }