[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/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index cfbee39..b6585ca 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -338,7 +338,7 @@
nfqnl_build_packet_message(struct nfqnl_instance *queue,
struct nfqnl_queue_entry *entry, int *errp)
{
- unsigned char *old_tail;
+ sk_buff_data_t old_tail;
size_t size;
size_t data_len = 0;
struct sk_buff *skb;
@@ -404,7 +404,7 @@
if (!skb)
goto nlmsg_failure;
- old_tail= skb->tail;
+ old_tail = skb->tail;
nlh = NLMSG_PUT(skb, 0, 0,
NFNL_SUBSYS_QUEUE << 8 | NFQNL_MSG_PACKET,
sizeof(struct nfgenmsg));