[NET]: Added GSO toggle

This patch adds a generic segmentation offload toggle that can be turned
on/off for each net device.  For now it only supports in TCPv4.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_if.c

@@ -376,15 +376,20 @@ void br_features_recompute(struct net_bridge *br)
 	features = br->feature_mask & ~NETIF_F_ALL_CSUM;
 
 	list_for_each_entry(p, &br->port_list, list) {
-		if (checksum & NETIF_F_NO_CSUM &&
-		    !(p->dev->features & NETIF_F_NO_CSUM))
+		unsigned long feature = p->dev->features;
+
+		if (checksum & NETIF_F_NO_CSUM && !(feature & NETIF_F_NO_CSUM))
 			checksum ^= NETIF_F_NO_CSUM | NETIF_F_HW_CSUM;
-		if (checksum & NETIF_F_HW_CSUM &&
-		    !(p->dev->features & NETIF_F_HW_CSUM))
+		if (checksum & NETIF_F_HW_CSUM && !(feature & NETIF_F_HW_CSUM))
 			checksum ^= NETIF_F_HW_CSUM | NETIF_F_IP_CSUM;
-		if (!(p->dev->features & NETIF_F_IP_CSUM))
+		if (!(feature & NETIF_F_IP_CSUM))
 			checksum = 0;
-		features &= p->dev->features;
+
+		if (feature & NETIF_F_GSO)
+			feature |= NETIF_F_TSO;
+		feature |= NETIF_F_GSO;
+
+		features &= feature;
 	}
 
 	br->dev->features = features | checksum | NETIF_F_LLTX;