hv_netvsc: improve VF device matching

The code to associate netvsc and VF devices can be made less error prone
by using a better matching algorithms.

On registration, use the permanent address which avoids any possible
issues caused by device MAC address being changed. For all other callbacks,
search by the netdevice pointer value to ensure getting the correct
network device.
Signed-off-by: NStephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/hyperv/netvsc_drv.c

@@ -1215,22 +1215,44 @@ static void netvsc_free_netdev(struct net_device *netdev)
 	free_netdev(netdev);
 }
 
-static struct net_device *get_netvsc_net_device(char *mac)
+static struct net_device *get_netvsc_bymac(const u8 *mac)
 {
-	struct net_device *dev, *found = NULL;
+	struct net_device *dev;
 
 	ASSERT_RTNL();
 
 	for_each_netdev(&init_net, dev) {
-		if (memcmp(dev->dev_addr, mac, ETH_ALEN) == 0) {
-			if (dev->netdev_ops != &device_ops)
-				continue;
-			found = dev;
-			break;
-		}
+		if (dev->netdev_ops != &device_ops)
+			continue;	/* not a netvsc device */
+
+		if (ether_addr_equal(mac, dev->perm_addr))
+			return dev;
+	}
+
+	return NULL;
+}
+
+static struct net_device *get_netvsc_byref(const struct net_device *vf_netdev)
+{
+	struct net_device *dev;
+
+	ASSERT_RTNL();
+
+	for_each_netdev(&init_net, dev) {
+		struct net_device_context *net_device_ctx;
+
+		if (dev->netdev_ops != &device_ops)
+			continue;	/* not a netvsc device */
+
+		net_device_ctx = netdev_priv(dev);
+		if (net_device_ctx->nvdev == NULL)
+			continue;	/* device is removed */
+
+		if (net_device_ctx->vf_netdev == vf_netdev)
+			return dev;	/* a match */
 	}
 
-	return found;
+	return NULL;
 }
 
 static int netvsc_register_vf(struct net_device *vf_netdev)
@@ -1239,12 +1261,15 @@ static int netvsc_register_vf(struct net_device *vf_netdev)
 	struct net_device_context *net_device_ctx;
 	struct netvsc_device *netvsc_dev;
 
+	if (vf_netdev->addr_len != ETH_ALEN)
+		return NOTIFY_DONE;
+
 	/*
 	 * We will use the MAC address to locate the synthetic interface to
 	 * associate with the VF interface. If we don't find a matching
 	 * synthetic interface, move on.
 	 */
-	ndev = get_netvsc_net_device(vf_netdev->dev_addr);
+	ndev = get_netvsc_bymac(vf_netdev->perm_addr);
 	if (!ndev)
 		return NOTIFY_DONE;
 
@@ -1284,16 +1309,13 @@ static int netvsc_vf_up(struct net_device *vf_netdev)
 	struct netvsc_device *netvsc_dev;
 	struct net_device_context *net_device_ctx;
 
-	ndev = get_netvsc_net_device(vf_netdev->dev_addr);
+	ndev = get_netvsc_byref(vf_netdev);
 	if (!ndev)
 		return NOTIFY_DONE;
 
 	net_device_ctx = netdev_priv(ndev);
 	netvsc_dev = net_device_ctx->nvdev;
 
-	if (!netvsc_dev || !net_device_ctx->vf_netdev)
-		return NOTIFY_DONE;
-
 	netdev_info(ndev, "VF up: %s\n", vf_netdev->name);
 	netvsc_inject_enable(net_device_ctx);
 
@@ -1322,16 +1344,13 @@ static int netvsc_vf_down(struct net_device *vf_netdev)
 	struct netvsc_device *netvsc_dev;
 	struct net_device_context *net_device_ctx;
 
-	ndev = get_netvsc_net_device(vf_netdev->dev_addr);
+	ndev = get_netvsc_byref(vf_netdev);
 	if (!ndev)
 		return NOTIFY_DONE;
 
 	net_device_ctx = netdev_priv(ndev);
 	netvsc_dev = net_device_ctx->nvdev;
 
-	if (!netvsc_dev || !net_device_ctx->vf_netdev)
-		return NOTIFY_DONE;
-
 	netdev_info(ndev, "VF down: %s\n", vf_netdev->name);
 	netvsc_inject_disable(net_device_ctx);
 	netvsc_switch_datapath(ndev, false);
@@ -1351,14 +1370,13 @@ static int netvsc_unregister_vf(struct net_device *vf_netdev)
 	struct netvsc_device *netvsc_dev;
 	struct net_device_context *net_device_ctx;
 
-	ndev = get_netvsc_net_device(vf_netdev->dev_addr);
+	ndev = get_netvsc_byref(vf_netdev);
 	if (!ndev)
 		return NOTIFY_DONE;
 
 	net_device_ctx = netdev_priv(ndev);
 	netvsc_dev = net_device_ctx->nvdev;
-	if (!netvsc_dev || !net_device_ctx->vf_netdev)
-		return NOTIFY_DONE;
+
 	netdev_info(ndev, "VF unregistering: %s\n", vf_netdev->name);
 	netvsc_inject_disable(net_device_ctx);
 	net_device_ctx->vf_netdev = NULL;