VXLAN: Support outer IPv4 Tx checksums by default

This change makes it so that if UDP CSUM is not specified we will default
to enabling it.  The main motivation behind this is the fact that with the
use of outer checksum we can greatly improve the performance for VXLAN
tunnels on devices that don't know how to parse tunnel headers.
Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Acked-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vxlan.c

@@ -1957,13 +1957,6 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 			goto drop;
 		sk = vxlan->vn4_sock->sock->sk;
 
-		if (info) {
-			if (info->key.tun_flags & TUNNEL_DONT_FRAGMENT)
-				df = htons(IP_DF);
-		} else {
-			udp_sum = !!(flags & VXLAN_F_UDP_CSUM);
-		}
-
 		rt = vxlan_get_route(vxlan, skb,
 				     rdst ? rdst->remote_ifindex : 0, tos,
 				     dst->sin.sin_addr.s_addr, &saddr,
@@ -1997,6 +1990,11 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 			return;
 		}
 
+		if (!info)
+			udp_sum = !(flags & VXLAN_F_UDP_ZERO_CSUM_TX);
+		else if (info->key.tun_flags & TUNNEL_DONT_FRAGMENT)
+			df = htons(IP_DF);
+
 		tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
 		ttl = ttl ? : ip4_dst_hoplimit(&rt->dst);
 		err = vxlan_build_skb(skb, &rt->dst, sizeof(struct iphdr),
@@ -2898,8 +2896,9 @@ static int vxlan_newlink(struct net *src_net, struct net_device *dev,
 	if (data[IFLA_VXLAN_PORT])
 		conf.dst_port = nla_get_be16(data[IFLA_VXLAN_PORT]);
 
-	if (data[IFLA_VXLAN_UDP_CSUM] && nla_get_u8(data[IFLA_VXLAN_UDP_CSUM]))
-		conf.flags |= VXLAN_F_UDP_CSUM;
+	if (data[IFLA_VXLAN_UDP_CSUM] &&
+	    !nla_get_u8(data[IFLA_VXLAN_UDP_CSUM]))
+		conf.flags |= VXLAN_F_UDP_ZERO_CSUM_TX;
 
 	if (data[IFLA_VXLAN_UDP_ZERO_CSUM6_TX] &&
 	    nla_get_u8(data[IFLA_VXLAN_UDP_ZERO_CSUM6_TX]))
@@ -3043,7 +3042,7 @@ static int vxlan_fill_info(struct sk_buff *skb, const struct net_device *dev)
 	    nla_put_u32(skb, IFLA_VXLAN_LIMIT, vxlan->cfg.addrmax) ||
 	    nla_put_be16(skb, IFLA_VXLAN_PORT, vxlan->cfg.dst_port) ||
 	    nla_put_u8(skb, IFLA_VXLAN_UDP_CSUM,
-			!!(vxlan->flags & VXLAN_F_UDP_CSUM)) ||
+			!(vxlan->flags & VXLAN_F_UDP_ZERO_CSUM_TX)) ||
 	    nla_put_u8(skb, IFLA_VXLAN_UDP_ZERO_CSUM6_TX,
 			!!(vxlan->flags & VXLAN_F_UDP_ZERO_CSUM6_TX)) ||
 	    nla_put_u8(skb, IFLA_VXLAN_UDP_ZERO_CSUM6_RX,

include/net/vxlan.h

@@ -197,7 +197,7 @@ struct vxlan_dev {
 #define VXLAN_F_L2MISS			0x08
 #define VXLAN_F_L3MISS			0x10
 #define VXLAN_F_IPV6			0x20
-#define VXLAN_F_UDP_CSUM		0x40
+#define VXLAN_F_UDP_ZERO_CSUM_TX	0x40
 #define VXLAN_F_UDP_ZERO_CSUM6_TX	0x80
 #define VXLAN_F_UDP_ZERO_CSUM6_RX	0x100
 #define VXLAN_F_REMCSUM_TX		0x200