net: pskb_expand_head() optimization

Move frags[] at the end of struct skb_shared_info, and make
pskb_expand_head() copy only the used part of it instead of whole array.

This should avoid kmemcheck warnings and speedup pskb_expand_head() as
well, avoiding a lot of cache misses.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index f5aa87e1e0c8..d89876b806a0 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -202,10 +202,11 @@ struct skb_shared_info {
          */
         atomic_t        dataref;
 
-        skb_frag_t      frags[MAX_SKB_FRAGS];
         /* Intermediate layers must ensure that destructor_arg
          * remains valid until skb destructor */
         void *          destructor_arg;
+        /* must be last field, see pskb_expand_head() */
+        skb_frag_t      frags[MAX_SKB_FRAGS];
 };
 
 /* We divide dataref into two halves.  The higher 16 bits hold references