tunnels: Optimize tx path

We currently dirty a cache line to update tunnel device stats
(tx_packets/tx_bytes). We better use the txq->tx_bytes/tx_packets
counters that already are present in cpu cache, in the cache
line shared with txq->_xmit_lock

This patch extends IPTUNNEL_XMIT() macro to use txq pointer
provided by the caller.

Also &tunnel->dev->stats can be replaced by &dev->stats

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

1 files changed, 3 insertions, 2 deletions

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index dbd19a78ca73..99da272951dc 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -555,7 +555,8 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
                                      struct net_device *dev)
 {
         struct ip_tunnel *tunnel = netdev_priv(dev);
-        struct net_device_stats *stats = &tunnel->dev->stats;
+        struct net_device_stats *stats = &dev->stats;
+        struct netdev_queue *txq = netdev_get_tx_queue(dev, 0);
         struct iphdr  *tiph = &tunnel->parms.iph;
         struct ipv6hdr *iph6 = ipv6_hdr(skb);
         u8     tos = tunnel->parms.iph.tos;
@@ -688,7 +689,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
                 if (!new_skb) {
                         ip_rt_put(rt);
-                        stats->tx_dropped++;
+                        txq->tx_dropped++;
                         dev_kfree_skb(skb);
                         return NETDEV_TX_OK;
                 }