[35/49] net: release dst entry while cache-hot for GSO case too

[Greg KH <gregkh@suse.de>]

2.6.32-longterm review patch.  If anyone has any objections, please let us know.

------------------

From: Krishna Kumar <krkumar2@in.ibm.com>

commit 068a2de57ddf4f472e32e7af868613c574ad1d88 upstream.

Non-GSO code drops dst entry for performance reasons, but
the same is missing for GSO code. Drop dst while cache-hot
for GSO case too.

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 net/core/dev.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1747,6 +1747,14 @@ gso:
 
 		skb->next = nskb->next;
 		nskb->next = NULL;
+
+		/*
+		 * If device doesnt need nskb->dst, release it right now while
+		 * its hot in this cpu cache
+		 */
+		if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
+			skb_dst_drop(nskb);
+
 		rc = ops->ndo_start_xmit(nskb, dev);
 		if (unlikely(rc != NETDEV_TX_OK)) {
 			nskb->next = skb->next;