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[SK_BUFF]: Convert skb->tail to sk_buff_data_t

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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>
This commit is contained in:
Arnaldo Carvalho de Melo
2007-04-19 20:29:13 -07:00
committed by David S. Miller
parent be8bd86321
commit 27a884dc3c
110 changed files with 396 additions and 329 deletions
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8
net/ipv4/esp4.c
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@@ -21,6 +21,7 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
struct blkcipher_desc desc;
struct esp_data *esp;
struct sk_buff *trailer;
u8 *tail;
int blksize;
int clen;
int alen;
@@ -49,12 +50,13 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
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 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
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) {