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

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: netdev@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: David Vrabel <david.vrabel@citrix.com>

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index e17879dd5d5a18e3efcfe0d64a4fb992d2967b96..95d664e3d09cc64b1ae016d5e0b5b7031e8721db 100644 (file)
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -1169,43 +1169,23 @@ static netdev_features_t xennet_fix_features(struct net_device *dev,
        netdev_features_t features)
 {
        struct netfront_info *np = netdev_priv(dev);
-       int val;
 
-       if (features & NETIF_F_SG) {
-               if (xenbus_scanf(XBT_NIL, np->xbdev->otherend, "feature-sg",
-                                "%d", &val) < 0)
-                       val = 0;
+       if (features & NETIF_F_SG &&
+           !xenbus_read_unsigned(np->xbdev->otherend, "feature-sg", 0))
+               features &= ~NETIF_F_SG;
 
-               if (!val)
-                       features &= ~NETIF_F_SG;
-       }
-
-       if (features & NETIF_F_IPV6_CSUM) {
-               if (xenbus_scanf(XBT_NIL, np->xbdev->otherend,
-                                "feature-ipv6-csum-offload", "%d", &val) < 0)
-                       val = 0;
-
-               if (!val)
-                       features &= ~NETIF_F_IPV6_CSUM;
-       }
-
-       if (features & NETIF_F_TSO) {
-               if (xenbus_scanf(XBT_NIL, np->xbdev->otherend,
-                                "feature-gso-tcpv4", "%d", &val) < 0)
-                       val = 0;
+       if (features & NETIF_F_IPV6_CSUM &&
+           !xenbus_read_unsigned(np->xbdev->otherend,
+                                 "feature-ipv6-csum-offload", 0))
+               features &= ~NETIF_F_IPV6_CSUM;
 
-               if (!val)
-                       features &= ~NETIF_F_TSO;
-       }
+       if (features & NETIF_F_TSO &&
+           !xenbus_read_unsigned(np->xbdev->otherend, "feature-gso-tcpv4", 0))
+               features &= ~NETIF_F_TSO;
 
-       if (features & NETIF_F_TSO6) {
-               if (xenbus_scanf(XBT_NIL, np->xbdev->otherend,
-                                "feature-gso-tcpv6", "%d", &val) < 0)
-                       val = 0;
-
-               if (!val)
-                       features &= ~NETIF_F_TSO6;
-       }
+       if (features & NETIF_F_TSO6 &&
+           !xenbus_read_unsigned(np->xbdev->otherend, "feature-gso-tcpv6", 0))
+               features &= ~NETIF_F_TSO6;
 
        return features;
 }
@@ -1821,18 +1801,13 @@ static int talk_to_netback(struct xenbus_device *dev,
        info->netdev->irq = 0;
 
        /* Check if backend supports multiple queues */
-       err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-                          "multi-queue-max-queues", "%u", &max_queues);
-       if (err < 0)
-               max_queues = 1;
+       max_queues = xenbus_read_unsigned(info->xbdev->otherend,
+                                         "multi-queue-max-queues", 1);
        num_queues = min(max_queues, xennet_max_queues);
 
        /* Check feature-split-event-channels */
-       err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-                          "feature-split-event-channels", "%u",
-                          &feature_split_evtchn);
-       if (err < 0)
-               feature_split_evtchn = 0;
+       feature_split_evtchn = xenbus_read_unsigned(info->xbdev->otherend,
+                                       "feature-split-event-channels", 0);
 
        /* Read mac addr. */
        err = xen_net_read_mac(dev, info->netdev->dev_addr);
@@ -1966,16 +1941,10 @@ static int xennet_connect(struct net_device *dev)
        struct netfront_info *np = netdev_priv(dev);
        unsigned int num_queues = 0;
        int err;
-       unsigned int feature_rx_copy;
        unsigned int j = 0;
        struct netfront_queue *queue = NULL;
 
-       err = xenbus_scanf(XBT_NIL, np->xbdev->otherend,
-                          "feature-rx-copy", "%u", &feature_rx_copy);
-       if (err != 1)
-               feature_rx_copy = 0;
-
-       if (!feature_rx_copy) {
+       if (!xenbus_read_unsigned(np->xbdev->otherend, "feature-rx-copy", 0)) {
                dev_info(&dev->dev,
                         "backend does not support copying receive path\n");
                return -ENODEV;