[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, 2 insertions, 2 deletions

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index abb94de33768..11007c75ae02 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -230,7 +230,7 @@ int ip6_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
         skb->priority = sk->sk_priority;
 
         mtu = dst_mtu(dst);
-        if ((skb->len <= mtu) || ipfragok) {
+        if ((skb->len <= mtu) || ipfragok || skb_shinfo(skb)->gso_size) {
                 IP6_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
                 return NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, skb, NULL, dst->dev,
                                 dst_output);
@@ -835,7 +835,7 @@ static inline int ip6_ufo_append_data(struct sock *sk,
                 /* specify the length of each IP datagram fragment*/
                 skb_shinfo(skb)->gso_size = mtu - fragheaderlen - 
                                             sizeof(struct frag_hdr);
-                skb_shinfo(skb)->gso_type = SKB_GSO_UDPV4;
+                skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
                 ipv6_select_ident(skb, &fhdr);
                 skb_shinfo(skb)->ip6_frag_id = fhdr.identification;
                 __skb_queue_tail(&sk->sk_write_queue, skb);