net/mlx5e: TC, Stub out ipv6 tun create header function

Improve mlx5e_route_lookup_ipv6 function structure by avoiding #ifdef then
return -EOPNOTSUPP in the middle of the function code.

To do so, we stub out mlx5e_tc_tun_create_header_ipv6 which is the only
caller of this helper function to avoid calling it altogether
when ipv6 is compiled out, which should also cleanup some compiler
warnings of unused variables.
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Reviewed-by: Eli Cohen <eli@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/en/tc_tun.c

@@ -141,7 +141,6 @@ static int mlx5e_route_lookup_ipv6(struct mlx5e_priv *priv,
 	struct dst_entry *dst;
 	struct neighbour *n;
 
-#if IS_ENABLED(CONFIG_INET) && IS_ENABLED(CONFIG_IPV6)
 	int ret;
 
 	ret = ipv6_stub->ipv6_dst_lookup(dev_net(mirred_dev), NULL, &dst,
@@ -157,9 +156,6 @@ static int mlx5e_route_lookup_ipv6(struct mlx5e_priv *priv,
 		dst_release(dst);
 		return ret;
 	}
-#else
-	return -EOPNOTSUPP;
-#endif
 
 	n = dst_neigh_lookup(dst, &fl6->daddr);
 	dst_release(dst);

drivers/net/ethernet/mellanox/mlx5/core/en/tc_tun.h

@@ -58,9 +58,16 @@ int mlx5e_tc_tun_create_header_ipv4(struct mlx5e_priv *priv,
 				    struct net_device *mirred_dev,
 				    struct mlx5e_encap_entry *e);
 
+#if IS_ENABLED(CONFIG_INET) && IS_ENABLED(CONFIG_IPV6)
 int mlx5e_tc_tun_create_header_ipv6(struct mlx5e_priv *priv,
 				    struct net_device *mirred_dev,
 				    struct mlx5e_encap_entry *e);
+#else
+static inline int
+mlx5e_tc_tun_create_header_ipv6(struct mlx5e_priv *priv,
+				struct net_device *mirred_dev,
+				struct mlx5e_encap_entry *e) { return -EOPNOTSUPP; }
+#endif
 
 bool mlx5e_tc_tun_device_to_offload(struct mlx5e_priv *priv,
 				    struct net_device *netdev);