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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
Download Patch File Download Diff File Expand all files Collapse all files

35
net/core/skbuff.c
View File

@@ -87,8 +87,9 @@ static struct kmem_cache *skbuff_fclone_cache __read_mostly;
void skb_over_panic(struct sk_buff *skb, int sz, void *here)
{
printk(KERN_EMERG "skb_over_panic: text:%p len:%d put:%d head:%p "
"data:%p tail:%p end:%p dev:%s\n",
here, skb->len, sz, skb->head, skb->data, skb->tail, skb->end,
"data:%p tail:%#lx end:%p dev:%s\n",
here, skb->len, sz, skb->head, skb->data,
(unsigned long)skb->tail, skb->end,
skb->dev ? skb->dev->name : "<NULL>");
BUG();
}
@@ -105,8 +106,9 @@ void skb_over_panic(struct sk_buff *skb, int sz, void *here)
void skb_under_panic(struct sk_buff *skb, int sz, void *here)
{
printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p "
"data:%p tail:%p end:%p dev:%s\n",
here, skb->len, sz, skb->head, skb->data, skb->tail, skb->end,
"data:%p tail:%#lx end:%p dev:%s\n",
here, skb->len, sz, skb->head, skb->data,
(unsigned long)skb->tail, skb->end,
skb->dev ? skb->dev->name : "<NULL>");
BUG();
}
@@ -167,7 +169,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
atomic_set(&skb->users, 1);
skb->head = data;
skb->data = data;
skb->tail = data;
skb_reset_tail_pointer(skb);
skb->end = data + size;
/* make sure we initialize shinfo sequentially */
shinfo = skb_shinfo(skb);
@@ -629,7 +631,12 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
/* Copy only real data... and, alas, header. This should be
* optimized for the cases when header is void. */
memcpy(data + nhead, skb->head, skb->tail - skb->head);
memcpy(data + nhead, skb->head,
skb->tail
#ifndef NET_SKBUFF_DATA_USES_OFFSET
- skb->head
#endif
);
memcpy(data + size, skb->end, sizeof(struct skb_shared_info));
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
@@ -645,9 +652,9 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
skb->head = data;
skb->end = data + size;
skb->data += off;
skb->tail += off;
#ifndef NET_SKBUFF_DATA_USES_OFFSET
/* {transport,network,mac}_header are relative to skb->head */
/* {transport,network,mac}_header and tail are relative to skb->head */
skb->tail += off;
skb->transport_header += off;
skb->network_header += off;
skb->mac_header += off;
@@ -762,7 +769,7 @@ int skb_pad(struct sk_buff *skb, int pad)
return 0;
}
ntail = skb->data_len + pad - (skb->end - skb->tail);
ntail = skb->data_len + pad - (skb->end - skb_tail_pointer(skb));
if (likely(skb_cloned(skb) || ntail > 0)) {
err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
if (unlikely(err))
@@ -863,7 +870,7 @@ done:
} else {
skb->len = len;
skb->data_len = 0;
skb->tail = skb->data + len;
skb_set_tail_pointer(skb, len);
}
return 0;
@@ -900,7 +907,7 @@ unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
* plus 128 bytes for future expansions. If we have enough
* room at tail, reallocate without expansion only if skb is cloned.
*/
int i, k, eat = (skb->tail + delta) - skb->end;
int i, k, eat = (skb_tail_pointer(skb) + delta) - skb->end;
if (eat > 0 || skb_cloned(skb)) {
if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
@@ -908,7 +915,7 @@ unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
return NULL;
}
if (skb_copy_bits(skb, skb_headlen(skb), skb->tail, delta))
if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta))
BUG();
/* Optimization: no fragments, no reasons to preestimate
@@ -1004,7 +1011,7 @@ pull_pages:
skb->tail += delta;
skb->data_len -= delta;
return skb->tail;
return skb_tail_pointer(skb);
}
/* Copy some data bits from skb to kernel buffer. */
@@ -1539,7 +1546,7 @@ static inline void skb_split_inside_header(struct sk_buff *skb,
skb1->len += skb1->data_len;
skb->data_len = 0;
skb->len = len;
skb->tail = skb->data + len;
skb_set_tail_pointer(skb, len);
}
static inline void skb_split_no_header(struct sk_buff *skb,