udp: use indirect call wrappers for GRO socket lookup

This avoids another indirect call for UDP GRO. Again, the test
for the IPv6 variant is performed first.

v1 -> v2:
 - adapted to INDIRECT_CALL_ changes
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/udp_offload.c

@@ -392,6 +392,8 @@ static struct sk_buff *udp_gro_receive_segment(struct list_head *head,
 	return NULL;
 }
 
+INDIRECT_CALLABLE_DECLARE(struct sock *udp6_lib_lookup_skb(struct sk_buff *skb,
+						   __be16 sport, __be16 dport));
 struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
 				struct udphdr *uh, udp_lookup_t lookup)
 {
@@ -403,7 +405,8 @@ struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
 	struct sock *sk;
 
 	rcu_read_lock();
-	sk = (*lookup)(skb, uh->source, uh->dest);
+	sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb,
+				udp4_lib_lookup_skb, skb, uh->source, uh->dest);
 	if (!sk)
 		goto out_unlock;
 
@@ -503,7 +506,8 @@ int udp_gro_complete(struct sk_buff *skb, int nhoff,
 	uh->len = newlen;
 
 	rcu_read_lock();
-	sk = (*lookup)(skb, uh->source, uh->dest);
+	sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb,
+				udp4_lib_lookup_skb, skb, uh->source, uh->dest);
 	if (sk && udp_sk(sk)->gro_enabled) {
 		err = udp_gro_complete_segment(skb);
 	} else if (sk && udp_sk(sk)->gro_complete) {