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>

1 files changed, 6 insertions, 3 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index d429c41e0dc4..c88426b51140 100644
--- 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;