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net: Add skb_gro_receive

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This patch adds the helper skb_gro_receive to merge packets for
GRO.  The current method is to allocate a new header skb and then
chain the original packets to its frag_list.  This is done to
make it easier to integrate into the existing GSO framework.

In future as GSO is moved into the drivers, we can undo this and
simply chain the original packets together.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2008-12-15 23:42:33 -08:00 committed by David S. Miller
parent 73cc19f155
commit 71d93b39e5
2 changed files with 61 additions and 0 deletions
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2
include/linux/skbuff.h
View file

@ -1687,6 +1687,8 @@ extern int skb_shift(struct sk_buff *tgt, struct sk_buff *skb,
int shiftlen);
extern struct sk_buff *skb_segment(struct sk_buff *skb, int features);
extern int skb_gro_receive(struct sk_buff **head,
struct sk_buff *skb);
static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
int len, void *buffer)

59
net/core/skbuff.c
View file

@ -2582,6 +2582,65 @@ err:
EXPORT_SYMBOL_GPL(skb_segment);
int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
{
struct sk_buff *p = *head;
struct sk_buff *nskb;
unsigned int headroom;
unsigned int hlen = p->data - skb_mac_header(p);
if (hlen + p->len + skb->len >= 65536)
return -E2BIG;
if (skb_shinfo(p)->frag_list)
goto merge;
headroom = skb_headroom(p);
nskb = netdev_alloc_skb(p->dev, headroom);
if (unlikely(!nskb))
return -ENOMEM;
__copy_skb_header(nskb, p);
nskb->mac_len = p->mac_len;
skb_reserve(nskb, headroom);
skb_set_mac_header(nskb, -hlen);
skb_set_network_header(nskb, skb_network_offset(p));
skb_set_transport_header(nskb, skb_transport_offset(p));
memcpy(skb_mac_header(nskb), skb_mac_header(p), hlen);
*NAPI_GRO_CB(nskb) = *NAPI_GRO_CB(p);
skb_shinfo(nskb)->frag_list = p;
skb_header_release(p);
nskb->prev = p;
nskb->data_len += p->len;
nskb->truesize += p->len;
nskb->len += p->len;
*head = nskb;
nskb->next = p->next;
p->next = NULL;
p = nskb;
merge:
NAPI_GRO_CB(p)->count++;
p->prev->next = skb;
p->prev = skb;
skb_header_release(skb);
p->data_len += skb->len;
p->truesize += skb->len;
p->len += skb->len;
NAPI_GRO_CB(skb)->same_flow = 1;
return 0;
}
EXPORT_SYMBOL_GPL(skb_gro_receive);
void __init skb_init(void)
{
skbuff_head_cache = kmem_cache_create("skbuff_head_cache",