vxlan: Have the NIC drivers do less work for offloads

This patch removes the burden from the NIC drivers to check if the
vxlan driver is enabled in the kernel and also makes available
the vxlan headrooms to them.

Signed-off-by: Joseph Gasparakis <joseph.gasparakis@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/vxlan.c

@@ -60,10 +60,6 @@
 
 #define VXLAN_N_VID	(1u << 24)
 #define VXLAN_VID_MASK	(VXLAN_N_VID - 1)
-/* IP header + UDP + VXLAN + Ethernet header */
-#define VXLAN_HEADROOM (20 + 8 + 8 + 14)
-/* IPv6 header + UDP + VXLAN + Ethernet header */
-#define VXLAN6_HEADROOM (40 + 8 + 8 + 14)
 #define VXLAN_HLEN (sizeof(struct udphdr) + sizeof(struct vxlanhdr))
 
 #define VXLAN_FLAGS 0x08000000	/* struct vxlanhdr.vx_flags required value. */

include/net/vxlan.h

@@ -36,5 +36,16 @@ int vxlan_xmit_skb(struct vxlan_sock *vs,
 
 __be16 vxlan_src_port(__u16 port_min, __u16 port_max, struct sk_buff *skb);
 
+/* IP header + UDP + VXLAN + Ethernet header */
+#define VXLAN_HEADROOM (20 + 8 + 8 + 14)
+/* IPv6 header + UDP + VXLAN + Ethernet header */
+#define VXLAN6_HEADROOM (40 + 8 + 8 + 14)
+
+#if IS_ENABLED(CONFIG_VXLAN)
 void vxlan_get_rx_port(struct net_device *netdev);
+#else
+static inline void vxlan_get_rx_port(struct net_device *netdev)
+{
+}
+#endif
 #endif