gro: Open-code frags copy in skb_gro_receive

gcc does a poor job at generating code for the memcpy of the frags
array in skb_gro_receive, which is the primary purpose of that
function when merging frags.  In particular, it can't utilise the
alignment information of the source and destination.  This patch
open-codes the copy so we process words instead of bytes.

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 d429c41..c88426b 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2673,6 +2673,9 @@ 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_frag_t *frag;
+               int i;
+
                if (skb_shinfo(p)->nr_frags + skb_shinfo(skb)->nr_frags >
                    MAX_SKB_FRAGS)
                        return -E2BIG;
@@ -2682,9 +2685,9 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
                skb_shinfo(skb)->frags[0].size -=
                        skb_gro_offset(skb) - skb_headlen(skb);
 
-               memcpy(skb_shinfo(p)->frags + skb_shinfo(p)->nr_frags,
-                      skb_shinfo(skb)->frags,
-                      skb_shinfo(skb)->nr_frags * sizeof(skb_frag_t));
+               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];
 
                skb_shinfo(p)->nr_frags += skb_shinfo(skb)->nr_frags;
                skb_shinfo(skb)->nr_frags = 0;