ipv6: sit: add GSO/TSO support

Now ipv6_gso_segment() is stackable, its relatively easy to
implement GSO/TSO support for SIT tunnels

Performance results, when segmentation is done after tunnel
device (as no NIC is yet enabled for TSO SIT support) :

Before patch :

lpq84:~# ./netperf -H 2002:af6:1153:: -Cc
MIGRATED TCP STREAM TEST from ::0 (::) port 0 AF_INET6 to 2002:af6:1153:: () port 0 AF_INET6
Recv   Send    Send                          Utilization       Service Demand
Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
Size   Size    Size     Time     Throughput  local    remote   local   remote
bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB

 87380  16384  16384    10.00      3168.31   4.81     4.64     2.988   2.877

After patch :

lpq84:~# ./netperf -H 2002:af6:1153:: -Cc
MIGRATED TCP STREAM TEST from ::0 (::) port 0 AF_INET6 to 2002:af6:1153:: () port 0 AF_INET6
Recv   Send    Send                          Utilization       Service Demand
Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
Size   Size    Size     Time     Throughput  local    remote   local   remote
bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB

 87380  16384  16384    10.00      5525.00   7.76     5.17     2.763   1.840

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 9 deletions

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 19269453a8ea..3a9038dd818d 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -933,10 +933,9 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
                 ttl = iph6->hop_limit;
         tos = INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
 
-        if (likely(!skb->encapsulation)) {
-                skb_reset_inner_headers(skb);
-                skb->encapsulation = 1;
-        }
+        skb = iptunnel_handle_offloads(skb, false, SKB_GSO_SIT);
+        if (IS_ERR(skb))
+                goto out;
 
         err = iptunnel_xmit(rt, skb, fl4.saddr, fl4.daddr, IPPROTO_IPV6, tos,
                             ttl, df, !net_eq(tunnel->net, dev_net(dev)));
@@ -946,8 +945,9 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 tx_error_icmp:
         dst_link_failure(skb);
 tx_error:
-        dev->stats.tx_errors++;
         dev_kfree_skb(skb);
+out:
+        dev->stats.tx_errors++;
         return NETDEV_TX_OK;
 }
 
@@ -956,13 +956,15 @@ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
         struct ip_tunnel *tunnel = netdev_priv(dev);
         const struct iphdr  *tiph = &tunnel->parms.iph;
 
-        if (likely(!skb->encapsulation)) {
-                skb_reset_inner_headers(skb);
-                skb->encapsulation = 1;
-        }
+        skb = iptunnel_handle_offloads(skb, false, SKB_GSO_IPIP);
+        if (IS_ERR(skb))
+                goto out;
 
         ip_tunnel_xmit(skb, dev, tiph, IPPROTO_IPIP);
         return NETDEV_TX_OK;
+out:
+        dev->stats.tx_errors++;
+        return NETDEV_TX_OK;
 }
 
 static netdev_tx_t sit_tunnel_xmit(struct sk_buff *skb,
@@ -1292,6 +1294,12 @@ static void ipip6_dev_free(struct net_device *dev)
         free_netdev(dev);
 }
 
+#define SIT_FEATURES (NETIF_F_SG           | \
+                      NETIF_F_FRAGLIST     | \
+                      NETIF_F_HIGHDMA      | \
+                      NETIF_F_GSO_SOFTWARE | \
+                      NETIF_F_HW_CSUM)
+
 static void ipip6_tunnel_setup(struct net_device *dev)
 {
         dev->netdev_ops         = &ipip6_netdev_ops;
@@ -1305,6 +1313,8 @@ static void ipip6_tunnel_setup(struct net_device *dev)
         dev->iflink             = 0;
         dev->addr_len           = 4;
         dev->features           |= NETIF_F_LLTX;
+        dev->features           |= SIT_FEATURES;
+        dev->hw_features        |= SIT_FEATURES;
 }
 
 static int ipip6_tunnel_init(struct net_device *dev)