[NET]: Merge TSO/UFO fields in sk_buff

Having separate fields in sk_buff for TSO/UFO (tso_size/ufo_size) is not
going to scale if we add any more segmentation methods (e.g., DCCP).  So
let's merge them.

They were used to tell the protocol of a packet.  This function has been
subsumed by the new gso_type field.  This is essentially a set of netdev
feature bits (shifted by 16 bits) that are required to process a specific
skb.  As such it's easy to tell whether a given device can process a GSO
skb: you just have to and the gso_type field and the netdev's features
field.

I've made gso_type a conjunction.  The idea is that you have a base type
(e.g., SKB_GSO_TCPV4) that can be modified further to support new features.
For example, if we add a hardware TSO type that supports ECN, they would
declare NETIF_F_TSO | NETIF_F_TSO_ECN.  All TSO packets with CWR set would
have a gso_type of SKB_GSO_TCPV4 | SKB_GSO_TCPV4_ECN while all other TSO
packets would be SKB_GSO_TCPV4.  This means that only the CWR packets need
to be emulated in software.

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

1 files changed, 9 insertions, 7 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 8538aac3d148..7624fd1d8f9f 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -210,8 +210,7 @@ static inline int ip_finish_output(struct sk_buff *skb)
                 return dst_output(skb);
         }
 #endif
-        if (skb->len > dst_mtu(skb->dst) &&
-            !(skb_shinfo(skb)->ufo_size || skb_shinfo(skb)->tso_size))
+        if (skb->len > dst_mtu(skb->dst) && !skb_shinfo(skb)->gso_size)
                 return ip_fragment(skb, ip_finish_output2);
         else
                 return ip_finish_output2(skb);
@@ -362,7 +361,7 @@ packet_routed:
         }
 
         ip_select_ident_more(iph, &rt->u.dst, sk,
-                             (skb_shinfo(skb)->tso_segs ?: 1) - 1);
+                             (skb_shinfo(skb)->gso_segs ?: 1) - 1);
 
         /* Add an IP checksum. */
         ip_send_check(iph);
@@ -744,7 +743,8 @@ static inline int ip_ufo_append_data(struct sock *sk,
                                (length - transhdrlen));
         if (!err) {
                 /* specify the length of each IP datagram fragment*/
-                skb_shinfo(skb)->ufo_size = (mtu - fragheaderlen);
+                skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
+                skb_shinfo(skb)->gso_type = SKB_GSO_UDPV4;
                 __skb_queue_tail(&sk->sk_write_queue, skb);
 
                 return 0;
@@ -1087,14 +1087,16 @@ ssize_t	ip_append_page(struct sock *sk, struct page *page,
 
         inet->cork.length += size;
         if ((sk->sk_protocol == IPPROTO_UDP) &&
-            (rt->u.dst.dev->features & NETIF_F_UFO))
-                skb_shinfo(skb)->ufo_size = (mtu - fragheaderlen);
+            (rt->u.dst.dev->features & NETIF_F_UFO)) {
+                skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
+                skb_shinfo(skb)->gso_type = SKB_GSO_UDPV4;
+        }
 
 
         while (size > 0) {
                 int i;
 
-                if (skb_shinfo(skb)->ufo_size)
+                if (skb_shinfo(skb)->gso_size)
                         len = size;
                 else {