bridge: Add support for TX vlan offload.

If some of the underlying devices support it, enable vlan offload on
transmit for bridge devices.  This allows senders to take advantage of the
hardware support, similar to other forms of acceleration.
Signed-off-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_device.c

@@ -212,6 +212,11 @@ static int br_set_tx_csum(struct net_device *dev, u32 data)
 	return 0;
 }
 
+static int br_set_flags(struct net_device *netdev, u32 data)
+{
+	return ethtool_op_set_flags(netdev, data, ETH_FLAG_TXVLAN);
+}
+
 #ifdef CONFIG_NET_POLL_CONTROLLER
 static void br_poll_controller(struct net_device *br_dev)
 {
@@ -304,6 +309,7 @@ static const struct ethtool_ops br_ethtool_ops = {
 	.get_ufo	= ethtool_op_get_ufo,
 	.set_ufo	= ethtool_op_set_ufo,
 	.get_flags	= ethtool_op_get_flags,
+	.set_flags	= br_set_flags,
 };
 
 static const struct net_device_ops br_netdev_ops = {
@@ -343,5 +349,5 @@ void br_dev_setup(struct net_device *dev)
 
 	dev->features = NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_HIGHDMA |
 			NETIF_F_GSO_MASK | NETIF_F_NO_CSUM | NETIF_F_LLTX |
-			NETIF_F_NETNS_LOCAL | NETIF_F_GSO;
+			NETIF_F_NETNS_LOCAL | NETIF_F_GSO | NETIF_F_HW_VLAN_TX;
 }