[SK_BUFF]: Convert skb->tail to sk_buff_data_t

So that it is also an offset from skb->head, reduces its size from 8 to 4 bytes
on 64bit architectures, allowing us to combine the 4 bytes hole left by the
layer headers conversion, reducing struct sk_buff size to 256 bytes, i.e. 4
64byte cachelines, and since the sk_buff slab cache is SLAB_HWCACHE_ALIGN...
:-)

Many calculations that previously required that skb->{transport,network,
mac}_header be first converted to a pointer now can be done directly, being
meaningful as offsets or pointers.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 9da8357addcd..f9469ea530cc 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -2357,7 +2357,7 @@ static struct sk_buff *fill_packet_ipv4(struct net_device *odev,
                 *vlan_encapsulated_proto = htons(ETH_P_IP);
         }
 
-        skb_set_network_header(skb, skb->tail - skb->data);
+        skb->network_header = skb->tail;
         skb->transport_header = skb->network_header + sizeof(struct iphdr);
         skb_put(skb, sizeof(struct iphdr) + sizeof(struct udphdr));
 
@@ -2696,7 +2696,7 @@ static struct sk_buff *fill_packet_ipv6(struct net_device *odev,
                 *vlan_encapsulated_proto = htons(ETH_P_IPV6);
         }
 
-        skb_set_network_header(skb, skb->tail - skb->data);
+        skb->network_header = skb->tail;
         skb->transport_header = skb->network_header + sizeof(struct ipv6hdr);
         skb_put(skb, sizeof(struct ipv6hdr) + sizeof(struct udphdr));