[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/ipv4/esp4.c b/net/ipv4/esp4.c
index de019f9..5e56139 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -21,6 +21,7 @@
struct blkcipher_desc desc;
struct esp_data *esp;
struct sk_buff *trailer;
+ u8 *tail;
int blksize;
int clen;
int alen;
@@ -49,12 +50,13 @@
goto error;
/* Fill padding... */
+ tail = skb_tail_pointer(trailer);
do {
int i;
for (i=0; i<clen-skb->len - 2; i++)
- *(u8*)(trailer->tail + i) = i+1;
+ tail[i] = i + 1;
} while (0);
- *(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2;
+ tail[clen - skb->len - 2] = (clen - skb->len) - 2;
pskb_put(skb, trailer, clen - skb->len);
__skb_push(skb, skb->data - skb_network_header(skb));
@@ -62,7 +64,7 @@
esph = (struct ip_esp_hdr *)(skb_network_header(skb) +
top_iph->ihl * 4);
top_iph->tot_len = htons(skb->len + alen);
- *(u8*)(trailer->tail - 1) = top_iph->protocol;
+ *(skb_tail_pointer(skb) - 1) = top_iph->protocol;
/* this is non-NULL only with UDP Encapsulation */
if (x->encap) {
