[IPV6]: Added GSO support for TCPv6

This patch adds GSO support for IPv6 and TCPv6.  This is based on a patch
by Ananda Raju <Ananda.Raju@neterion.com>.  His original description is:

	This patch enables TSO over IPv6. Currently Linux network stacks
	restricts TSO over IPv6 by clearing of the NETIF_F_TSO bit from
	"dev->features". This patch will remove this restriction.

	This patch will introduce a new flag NETIF_F_TSO6 which will be used
	to check whether device supports TSO over IPv6. If device support TSO
	over IPv6 then we don't clear of NETIF_F_TSO and which will make the
	TCP layer to create TSO packets. Any device supporting TSO over IPv6
	will set NETIF_F_TSO6 flag in "dev->features" along with NETIF_F_TSO.

	In case when user disables TSO using ethtool, NETIF_F_TSO will get
	cleared from "dev->features". So even if we have NETIF_F_TSO6 we don't
	get TSO packets created by TCP layer.

	SKB_GSO_TCPV4 renamed to SKB_GSO_TCP to make it generic GSO packet.
	SKB_GSO_UDPV4 renamed to SKB_GSO_UDP as UFO is not a IPv4 feature.
	UFO is supported over IPv6 also

	The following table shows there is significant improvement in
	throughput with normal frames and CPU usage for both normal and jumbo.

	--------------------------------------------------
	|          |     1500        |      9600         |
	|          ------------------|-------------------|
	|          | thru     CPU    |  thru     CPU     |
	--------------------------------------------------
	| TSO OFF  | 2.00   5.5% id  |  5.66   20.0% id  |
	--------------------------------------------------
	| TSO ON   | 2.63   78.0 id  |  5.67   39.0% id  |
	--------------------------------------------------

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

1 files changed, 4 insertions, 2 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 59918be91d0a..57d7d4965f9a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -171,13 +171,15 @@ enum {
 
 enum {
         SKB_GSO_TCPV4 = 1 << 0,
-        SKB_GSO_UDPV4 = 1 << 1,
+        SKB_GSO_UDP = 1 << 1,
 
         /* This indicates the skb is from an untrusted source. */
         SKB_GSO_DODGY = 1 << 2,
 
         /* This indicates the tcp segment has CWR set. */
-        SKB_GSO_TCPV4_ECN = 1 << 3,
+        SKB_GSO_TCP_ECN = 1 << 3,
+
+        SKB_GSO_TCPV6 = 1 << 4,
 };
 
 /**