[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>
diff --git a/drivers/net/macb.c b/drivers/net/macb.c
index 0c3649b..98bf51a 100644
--- a/drivers/net/macb.c
+++ b/drivers/net/macb.c
@@ -575,7 +575,8 @@
int i;
dev_dbg(&bp->pdev->dev,
"start_xmit: len %u head %p data %p tail %p end %p\n",
- skb->len, skb->head, skb->data, skb->tail, skb->end);
+ skb->len, skb->head, skb->data,
+ skb_tail_pointer(skb), skb->end);
dev_dbg(&bp->pdev->dev,
"data:");
for (i = 0; i < 16; i++)