vlan: Add ability to always enable TSO/UFO

Since the real device can segment packets by software, a vlan device
can set TSO/UFO even when the real device doesn't have those features.
Unlike GSO, this allows packets to be segmented after Qdisc.

Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/8021q/vlan_dev.c

@@ -579,11 +579,12 @@ static int vlan_dev_init(struct net_device *dev)
 		      (1<<__LINK_STATE_PRESENT);
 
 	dev->hw_features = NETIF_F_ALL_CSUM | NETIF_F_SG |
-			   NETIF_F_FRAGLIST | NETIF_F_ALL_TSO |
+			   NETIF_F_FRAGLIST | NETIF_F_GSO_SOFTWARE |
 			   NETIF_F_HIGHDMA | NETIF_F_SCTP_CSUM |
 			   NETIF_F_ALL_FCOE;
 
-	dev->features |= real_dev->vlan_features | NETIF_F_LLTX;
+	dev->features |= real_dev->vlan_features | NETIF_F_LLTX |
+			 NETIF_F_GSO_SOFTWARE;
 	dev->gso_max_size = real_dev->gso_max_size;
 	if (dev->features & NETIF_F_VLAN_FEATURES)
 		netdev_warn(real_dev, "VLAN features are set incorrectly.  Q-in-Q configurations may not work correctly.\n");
@@ -648,7 +649,7 @@ static netdev_features_t vlan_dev_fix_features(struct net_device *dev,
 	features |= NETIF_F_RXCSUM;
 	features = netdev_intersect_features(features, real_dev->features);
 
-	features |= old_features & NETIF_F_SOFT_FEATURES;
+	features |= old_features & (NETIF_F_SOFT_FEATURES | NETIF_F_GSO_SOFTWARE);
 	features |= NETIF_F_LLTX;
 
 	return features;