net: make dev_disable_lro use physical device if passed a vlan dev (v2)

If the device passed into dev_disable_lro is a vlan, then repoint the dev
poniter so that we actually modify the underlying physical device.
Signed-of-by: Neil Horman <nhorman@tuxdriver.com>
CC: davem@davemloft.net
CC: bhutchings@solarflare.com
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/dev.c

@@ -1308,6 +1308,13 @@ void dev_disable_lro(struct net_device *dev)
 {
 	u32 flags;
 
+	/*
+	 * If we're trying to disable lro on a vlan device
+	 * use the underlying physical device instead
+	 */
+	if (is_vlan_dev(dev))
+		dev = vlan_dev_real_dev(dev);
+
 	if (dev->ethtool_ops && dev->ethtool_ops->get_flags)
 		flags = dev->ethtool_ops->get_flags(dev);
 	else