gro: Do not merge paged packets into frag_list

gro: Do not merge paged packets into frag_list

Bigger is not always better :)

It was easy to continue to merged packets into frag_list after the
page array is full.  However, this turns out to be worse than LRO
because frag_list is a much less efficient form of storage than the
page array.  So we're better off stopping the merge and starting
a new entry with an empty page array.

In future we can optimise this further by doing frag_list merging
but making sure that we continue to fill in the page array.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f9f4065..d386f10 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2591,9 +2591,11 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
 
        if (skb_shinfo(p)->frag_list)
                goto merge;
-       else if (skb_headlen(skb) <= skb_gro_offset(skb) &&
-                skb_shinfo(p)->nr_frags + skb_shinfo(skb)->nr_frags <=
-                MAX_SKB_FRAGS) {
+       else if (skb_headlen(skb) <= skb_gro_offset(skb)) {
+               if (skb_shinfo(p)->nr_frags + skb_shinfo(skb)->nr_frags >
+                   MAX_SKB_FRAGS)
+                       return -E2BIG;
+
                skb_shinfo(skb)->frags[0].page_offset +=
                        skb_gro_offset(skb) - skb_headlen(skb);
                skb_shinfo(skb)->frags[0].size -=