net: release dst entry while cache-hot for GSO case too

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: NKrishna Kumar <krkumar2@in.ibm.com>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/dev.c

@@ -1853,6 +1853,14 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
 
 		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)) {
 			if (rc & ~NETDEV_TX_MASK)