[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/net/core/dev.c b/net/core/dev.c
index 6562e57..86dc9f6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1069,7 +1069,7 @@
skb_reset_mac_header(skb2);
if (skb_network_header(skb2) < skb2->data ||
- skb_network_header(skb2) > skb2->tail) {
+ skb2->network_header > skb2->tail) {
if (net_ratelimit())
printk(KERN_CRIT "protocol %04x is "
"buggy, dev %s\n",
@@ -1175,7 +1175,7 @@
BUG_ON(offset > (int)skb->len);
csum = skb_checksum(skb, offset, skb->len-offset, 0);
- offset = skb->tail - skb_transport_header(skb);
+ offset = skb->tail - skb->transport_header;
BUG_ON(offset <= 0);
BUG_ON(skb->csum_offset + 2 > offset);