[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/skbuff.c b/net/core/skbuff.c
index a48b086..ddcbc4d 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -87,8 +87,9 @@
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_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 @@
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 @@
/* 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 @@
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 @@
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 @@
} 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 @@
* 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 @@
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 @@
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 @@
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,
