@@ -2585,6 +2585,9 @@ static inline bool tcp_ao_required(struct sock *sk, const void *saddr,
 	struct tcp_ao_info *ao_info;
 	struct tcp_ao_key *ao_key;
 
+	if (!static_branch_unlikely(&tcp_ao_needed.key))
+		return false;
+
 	ao_info = rcu_dereference_check(tcp_sk(sk)->ao_info,
 					lockdep_sock_is_held(sk));
 	if (!ao_info)

@@ -138,6 +138,8 @@ do {									\
 
 #ifdef CONFIG_TCP_AO
 /* TCP-AO structures and functions */
+#include <linux/jump_label.h>
+extern struct static_key_false_deferred tcp_ao_needed;
 
 struct tcp4_ao_context {
 	__be32		saddr;

@@ -17,6 +17,9 @@
 #include <net/ipv6.h>
 #include <net/icmp.h>
 
+DEFINE_STATIC_KEY_DEFERRED_FALSE(tcp_ao_needed, HZ);
+EXPORT_SYMBOL_GPL(tcp_ao_needed);
+
 int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,
 			    unsigned int len)
 {

@@ -58,6 +61,9 @@ bool tcp_ao_ignore_icmp(struct sock *sk, int type, int code)
 	struct tcp_ao_info *ao;
 	bool ignore_icmp = false;
 
+	if (!static_branch_unlikely(&tcp_ao_needed.key))
+		return false;
+
 	/* RFC5925, 7.8:
 	 * >> A TCP-AO implementation MUST default to ignore incoming ICMPv4
 	 * messages of Type 3 (destination unreachable), Codes 2-4 (protocol

@@ -198,6 +204,9 @@ static struct tcp_ao_key *__tcp_ao_do_lookup(const struct sock *sk,
 	struct tcp_ao_key *key;
 	struct tcp_ao_info *ao;
 
+	if (!static_branch_unlikely(&tcp_ao_needed.key))
+		return NULL;
+
 	ao = rcu_dereference_check(tcp_sk(sk)->ao_info,
 				   lockdep_sock_is_held(sk));
 	if (!ao)

@@ -292,6 +301,7 @@ void tcp_ao_destroy_sock(struct sock *sk, bool twsk)
 	}
 
 	kfree_rcu(ao, rcu);
+	static_branch_slow_dec_deferred(&tcp_ao_needed);
 }
 
 void tcp_ao_time_wait(struct tcp_timewait_sock *tcptw, struct tcp_sock *tp)

@@ -1107,6 +1117,11 @@ int tcp_ao_copy_all_matching(const struct sock *sk, struct sock *newsk,
 		goto free_and_exit;
 	}
 
+	if (!static_key_fast_inc_not_disabled(&tcp_ao_needed.key.key)) {
+		ret = -EUSERS;
+		goto free_and_exit;
+	}
+
 	key_head = rcu_dereference(hlist_first_rcu(&new_ao->head));
 	first_key = hlist_entry_safe(key_head, struct tcp_ao_key, node);
 

@@ -1523,6 +1538,10 @@ static int tcp_ao_add_cmd(struct sock *sk, unsigned short int family,
 
 	tcp_ao_link_mkt(ao_info, key);
 	if (first) {
+		if (!static_branch_inc(&tcp_ao_needed.key)) {
+			ret = -EUSERS;
+			goto err_free_sock;
+		}
 		sk_gso_disable(sk);
 		rcu_assign_pointer(tcp_sk(sk)->ao_info, ao_info);
 	}

@@ -1788,6 +1807,10 @@ static int tcp_ao_info_cmd(struct sock *sk, unsigned short int family,
 	if (new_rnext)
 		WRITE_ONCE(ao_info->rnext_key, new_rnext);
 	if (first) {
+		if (!static_branch_inc(&tcp_ao_needed.key)) {
+			err = -EUSERS;
+			goto out;
+		}
 		sk_gso_disable(sk);
 		rcu_assign_pointer(tcp_sk(sk)->ao_info, ao_info);
 	}

@@ -3524,17 +3524,14 @@ static inline bool tcp_may_update_window(const struct tcp_sock *tp,
 		(ack_seq == tp->snd_wl1 && nwin > tp->snd_wnd);
 }
 
-/* If we update tp->snd_una, also update tp->bytes_acked */
-static void tcp_snd_una_update(struct tcp_sock *tp, u32 ack)
+static void tcp_snd_sne_update(struct tcp_sock *tp, u32 ack)
 {
-	u32 delta = ack - tp->snd_una;
 #ifdef CONFIG_TCP_AO
 	struct tcp_ao_info *ao;
-#endif
 
-	sock_owned_by_me((struct sock *)tp);
-	tp->bytes_acked += delta;
-#ifdef CONFIG_TCP_AO
+	if (!static_branch_unlikely(&tcp_ao_needed.key))
+		return;
+
 	ao = rcu_dereference_protected(tp->ao_info,
 				       lockdep_sock_is_held((struct sock *)tp));
 	if (ao) {

@@ -3543,20 +3540,27 @@ static void tcp_snd_una_update(struct tcp_sock *tp, u32 ack)
 		ao->snd_sne_seq = ack;
 	}
 #endif
+}
+
+/* If we update tp->snd_una, also update tp->bytes_acked */
+static void tcp_snd_una_update(struct tcp_sock *tp, u32 ack)
+{
+	u32 delta = ack - tp->snd_una;
+
+	sock_owned_by_me((struct sock *)tp);
+	tp->bytes_acked += delta;
+	tcp_snd_sne_update(tp, ack);
 	tp->snd_una = ack;
 }
 
-/* If we update tp->rcv_nxt, also update tp->bytes_received */
-static void tcp_rcv_nxt_update(struct tcp_sock *tp, u32 seq)
+static void tcp_rcv_sne_update(struct tcp_sock *tp, u32 seq)
 {
-	u32 delta = seq - tp->rcv_nxt;
 #ifdef CONFIG_TCP_AO
 	struct tcp_ao_info *ao;
-#endif
 
-	sock_owned_by_me((struct sock *)tp);
-	tp->bytes_received += delta;
-#ifdef CONFIG_TCP_AO
+	if (!static_branch_unlikely(&tcp_ao_needed.key))
+		return;
+
 	ao = rcu_dereference_protected(tp->ao_info,
 				       lockdep_sock_is_held((struct sock *)tp));
 	if (ao) {

@@ -3565,6 +3569,16 @@ static void tcp_rcv_nxt_update(struct tcp_sock *tp, u32 seq)
 		ao->rcv_sne_seq = seq;
 	}
 #endif
+}
+
+/* If we update tp->rcv_nxt, also update tp->bytes_received */
+static void tcp_rcv_nxt_update(struct tcp_sock *tp, u32 seq)
+{
+	u32 delta = seq - tp->rcv_nxt;
+
+	sock_owned_by_me((struct sock *)tp);
+	tp->bytes_received += delta;
+	tcp_rcv_sne_update(tp, seq);
 	WRITE_ONCE(tp->rcv_nxt, seq);
 }