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Commit 66e92fcf authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

gro: Nasty optimisations for page frags in skb_gro_receive 



This patch reverses the direction of the frags array copy in
skb_gro_receive in order simplify the loop conditional.  It
also avoids touching the first element of the original frags
array.

Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent cb18978c

net/core/skbuff.c

+15 −10
Original line number Original line Diff line number Diff line
@@ -2676,21 +2676,26 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb) 
		goto merge;

		goto merge;

	else if (headlen <= offset) {

	else if (headlen <= offset) {

		skb_frag_t *frag;

		skb_frag_t *frag;

		int i;

		skb_frag_t *frag2;

		int i = skb_shinfo(skb)->nr_frags;

		int nr_frags = skb_shinfo(p)->nr_frags + i;



		offset -= headlen;





		if (skb_shinfo(p)->nr_frags + skb_shinfo(skb)->nr_frags >

		if (nr_frags > MAX_SKB_FRAGS)

		    MAX_SKB_FRAGS)

			return -E2BIG;

			return -E2BIG;





		skb_shinfo(skb)->frags[0].page_offset += offset - headlen;

		skb_shinfo(p)->nr_frags = nr_frags;

		skb_shinfo(skb)->frags[0].size -= offset - headlen;

		skb_shinfo(skb)->nr_frags = 0;





		frag = skb_shinfo(p)->frags + skb_shinfo(p)->nr_frags;

		frag = skb_shinfo(p)->frags + nr_frags;

		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)

		frag2 = skb_shinfo(skb)->frags + i;

			*frag++ = skb_shinfo(skb)->frags[i];

		do {

			*--frag = *--frag2;

		} while (--i);





		skb_shinfo(p)->nr_frags += skb_shinfo(skb)->nr_frags;

		frag->page_offset += offset;

		skb_shinfo(skb)->nr_frags = 0;

		frag->size -= offset;





		skb->truesize -= skb->data_len;

		skb->truesize -= skb->data_len;

		skb->len -= skb->data_len;

		skb->len -= skb->data_len;