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net: makes skb_splice_bits() aware of skb->head_frag

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__skb_splice_bits() can check if skb to be spliced has its skb->head
mapped to a page fragment, instead of a kmalloc() area.

If so we can avoid a copy of the skb head and get a reference on
underlying page.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Cc: Matt Carlson <mcarlson@broadcom.com>
Cc: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2012-04-27 02:10:03 +00:00 committed by David S. Miller
parent 329033f645
commit 1d0c0b328a
1 changed files with 7 additions and 3 deletions
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10
net/core/skbuff.c
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@ -1699,14 +1699,18 @@ static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
struct splice_pipe_desc *spd, struct sock *sk) struct splice_pipe_desc *spd, struct sock *sk)
{ {
int seg; int seg;
bool head_is_linear = !skb->head_frag;
/* /* map the linear part :
* map the linear part * If skb->head_frag is set, this 'linear' part is backed
* by a fragment, and we can avoid a copy.
*/ */
if (__splice_segment(virt_to_page(skb->data), if (__splice_segment(virt_to_page(skb->data),
(unsigned long) skb->data & (PAGE_SIZE - 1), (unsigned long) skb->data & (PAGE_SIZE - 1),
skb_headlen(skb), skb_headlen(skb),
offset, len, skb, spd, true, sk, pipe)) offset, len, skb, spd,
head_is_linear,
sk, pipe))
return true; return true;
/* /*