From 66e92fcf1ded5dd0da30d016ed47882eb183ec71 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Tue, 26 May 2009 18:50:32 +0000 Subject: [PATCH] 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: Herbert Xu Signed-off-by: David S. Miller --- net/core/skbuff.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 168e949..19afb18 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -2676,21 +2676,26 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb) goto merge; else if (headlen <= offset) { 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 > - MAX_SKB_FRAGS) + if (nr_frags > MAX_SKB_FRAGS) return -E2BIG; - skb_shinfo(skb)->frags[0].page_offset += offset - headlen; - skb_shinfo(skb)->frags[0].size -= offset - headlen; + skb_shinfo(p)->nr_frags = nr_frags; + skb_shinfo(skb)->nr_frags = 0; - frag = skb_shinfo(p)->frags + skb_shinfo(p)->nr_frags; - for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) - *frag++ = skb_shinfo(skb)->frags[i]; + frag = skb_shinfo(p)->frags + nr_frags; + frag2 = skb_shinfo(skb)->frags + i; + do { + *--frag = *--frag2; + } while (--i); - skb_shinfo(p)->nr_frags += skb_shinfo(skb)->nr_frags; - skb_shinfo(skb)->nr_frags = 0; + frag->page_offset += offset; + frag->size -= offset; skb->truesize -= skb->data_len; skb->len -= skb->data_len; -- 2.7.4