Commit 1d0c0b32 authored Apr 27, 2012 by Eric Dumazet Committed by David S. Miller Apr 30, 2012

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



__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>

parent 329033f6

net/core/skbuff.c

+7 −3

Original line number	Diff line number	Diff line
		@@ -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)
		{
		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),
		(unsigned long) skb->data & (PAGE_SIZE - 1),
		skb_headlen(skb),
		offset, len, skb, spd, true, sk, pipe))
		offset, len, skb, spd,
		head_is_linear,
		sk, pipe))
		return true;

		/*