Avoid the socket lookup cost in udp_gro_receive if no socket has a
udp tunnel callback configured.
udp_sk(sk)->gro_receive requires a registration with
setup_udp_tunnel_sock, which enables the static key.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
 
 void udp_init(void);
 
+DECLARE_STATIC_KEY_FALSE(udp_encap_needed_key);
 void udp_encap_enable(void);
 #if IS_ENABLED(CONFIG_IPV6)
+DECLARE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
 void udpv6_encap_enable(void);
 #endif
 
 
        return 0;
 }
 
-static DEFINE_STATIC_KEY_FALSE(udp_encap_needed_key);
+DEFINE_STATIC_KEY_FALSE(udp_encap_needed_key);
 void udp_encap_enable(void)
 {
        static_branch_enable(&udp_encap_needed_key);
 
 {
        struct udphdr *uh = udp_gro_udphdr(skb);
 
-       if (unlikely(!uh))
+       if (unlikely(!uh) || !static_branch_unlikely(&udp_encap_needed_key))
                goto flush;
 
        /* Don't bother verifying checksum if we're going to flush anyway. */
 
        __udp6_lib_err(skb, opt, type, code, offset, info, &udp_table);
 }
 
-static DEFINE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
+DEFINE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
 void udpv6_encap_enable(void)
 {
        static_branch_enable(&udpv6_encap_needed_key);
 
 {
        struct udphdr *uh = udp_gro_udphdr(skb);
 
-       if (unlikely(!uh))
+       if (unlikely(!uh) || !static_branch_unlikely(&udpv6_encap_needed_key))
                goto flush;
 
        /* Don't bother verifying checksum if we're going to flush anyway. */