[NET]: Convert hh_lock to seqlock.

The hard header cache is in the main output path, so using
seqlock instead of reader/writer lock should reduce overhead.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 11 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index a35209d517ad..f071f84808fa 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -164,7 +164,6 @@ EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
 static inline int ip_finish_output2(struct sk_buff *skb)
 {
         struct dst_entry *dst = skb->dst;
-        struct hh_cache *hh = dst->hh;
         struct net_device *dev = dst->dev;
         int hh_len = LL_RESERVED_SPACE(dev);
 
@@ -183,16 +182,9 @@ static inline int ip_finish_output2(struct sk_buff *skb)
                 skb = skb2;
         }
 
-        if (hh) {
-                int hh_alen;
-
-                read_lock_bh(&hh->hh_lock);
-                hh_alen = HH_DATA_ALIGN(hh->hh_len);
-                memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
-                read_unlock_bh(&hh->hh_lock);
-                skb_push(skb, hh->hh_len);
-                return hh->hh_output(skb);
-        } else if (dst->neighbour)
+        if (dst->hh)
+                return neigh_hh_output(dst->hh, skb);
+        else if (dst->neighbour)
                 return dst->neighbour->output(skb);
 
         if (net_ratelimit())