net/tcp: Use static_branch_tcp_{md5,ao} to drop ifdefs

It's possible to clean-up some ifdefs by hiding that
tcp_{md5,ao}_needed static branch is defined and compiled only
under related configs, since commit 4c8530dc ("net/tcp: Only produce
AO/MD5 logs if there are any keys").
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/tcp.h

@@ -2386,21 +2386,15 @@ static inline void tcp_get_current_key(const struct sock *sk,
 
 static inline bool tcp_key_is_md5(const struct tcp_key *key)
 {
-#ifdef CONFIG_TCP_MD5SIG
-	if (static_branch_unlikely(&tcp_md5_needed.key) &&
-	    key->type == TCP_KEY_MD5)
-		return true;
-#endif
+	if (static_branch_tcp_md5())
+		return key->type == TCP_KEY_MD5;
 	return false;
 }
 
 static inline bool tcp_key_is_ao(const struct tcp_key *key)
 {
-#ifdef CONFIG_TCP_AO
-	if (static_branch_unlikely(&tcp_ao_needed.key) &&
-	    key->type == TCP_KEY_AO)
-		return true;
-#endif
+	if (static_branch_tcp_ao())
+		return key->type == TCP_KEY_AO;
 	return false;
 }
 

net/ipv4/tcp_ipv4.c

@@ -1054,12 +1054,10 @@ static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
 #else
 	if (0) {
 #endif
-#ifdef CONFIG_TCP_MD5SIG
-	} else if (static_branch_unlikely(&tcp_md5_needed.key)) {
+	} else if (static_branch_tcp_md5()) {
 		key.md5_key = tcp_twsk_md5_key(tcptw);
 		if (key.md5_key)
 			key.type = TCP_KEY_MD5;
-#endif
 	}
 
 	tcp_v4_send_ack(sk, skb,
@@ -1128,8 +1126,7 @@ static void tcp_v4_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
 #else
 	if (0) {
 #endif
-#ifdef CONFIG_TCP_MD5SIG
-	} else if (static_branch_unlikely(&tcp_md5_needed.key)) {
+	} else if (static_branch_tcp_md5()) {
 		const union tcp_md5_addr *addr;
 		int l3index;
 
@@ -1138,7 +1135,6 @@ static void tcp_v4_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
 		key.md5_key = tcp_md5_do_lookup(sk, l3index, addr, AF_INET);
 		if (key.md5_key)
 			key.type = TCP_KEY_MD5;
-#endif
 	}
 
 	tcp_v4_send_ack(sk, skb, seq,