[PATCH v3] tcp: Use BPF timeout setting for SYN ACK RTO

@@ -70,6 +70,7 @@ struct request_sock {
 	struct saved_syn		*saved_syn;
 	u32				secid;
 	u32				peer_secid;
+	u32				timeout;
 };
 
 static inline struct request_sock *inet_reqsk(const struct sock *sk)

@@ -104,6 +105,7 @@ reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener,
 	sk_node_init(&req_to_sk(req)->sk_node);
 	sk_tx_queue_clear(req_to_sk(req));
 	req->saved_syn = NULL;
+	req->timeout = 0;
 	req->num_timeout = 0;
 	req->num_retrans = 0;
 	req->sk = NULL;

@@ -2323,7 +2323,7 @@ static inline u32 tcp_timeout_init(struct sock *sk)
 
 	if (timeout <= 0)
 		timeout = TCP_TIMEOUT_INIT;
-	return timeout;
+	return min_t(int, timeout, TCP_RTO_MAX);
 }
 
 static inline u32 tcp_rwnd_init_bpf(struct sock *sk)

@@ -870,7 +870,9 @@ static void reqsk_timer_handler(struct timer_list *t)
 
 		if (req->num_timeout++ == 0)
 			atomic_dec(&queue->young);
-		timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
+		timeo = min_t(unsigned long,
+			      (unsigned long)req->timeout << req->num_timeout,
+			      TCP_RTO_MAX);
 		mod_timer(&req->rsk_timer, jiffies + timeo);
 
 		if (!nreq)

@@ -6706,6 +6706,7 @@ struct request_sock *inet_reqsk_alloc(const struct request_sock_ops *ops,
 		ireq->ireq_state = TCP_NEW_SYN_RECV;
 		write_pnet(&ireq->ireq_net, sock_net(sk_listener));
 		ireq->ireq_family = sk_listener->sk_family;
+		req->timeout = TCP_TIMEOUT_INIT;
 	}
 
 	return req;

@@ -6922,9 +6923,10 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 		sock_put(fastopen_sk);
 	} else {
 		tcp_rsk(req)->tfo_listener = false;
-		if (!want_cookie)
-			inet_csk_reqsk_queue_hash_add(sk, req,
-				tcp_timeout_init((struct sock *)req));
+		if (!want_cookie) {
+			req->timeout = tcp_timeout_init((struct sock *)req);
+			inet_csk_reqsk_queue_hash_add(sk, req, req->timeout);
+		}
 		af_ops->send_synack(sk, dst, &fl, req, &foc,
 				    !want_cookie ? TCP_SYNACK_NORMAL :
 						   TCP_SYNACK_COOKIE,

@@ -583,6 +583,8 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 		tcp_parse_options(sock_net(sk), skb, &tmp_opt, 0, NULL);
 
 		if (tmp_opt.saw_tstamp) {
+			unsigned long timeo;
+
 			tmp_opt.ts_recent = req->ts_recent;
 			if (tmp_opt.rcv_tsecr)
 				tmp_opt.rcv_tsecr -= tcp_rsk(req)->ts_off;

@@ -590,7 +592,10 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 			 * it can be estimated (approximately)
 			 * from another data.
 			 */
-			tmp_opt.ts_recent_stamp = ktime_get_seconds() - ((TCP_TIMEOUT_INIT/HZ)<<req->num_timeout);
+			timeo = min_t(unsigned long,
+				      (unsigned long)req->timeout << req->num_timeout,
+				      TCP_RTO_MAX);
+			tmp_opt.ts_recent_stamp = ktime_get_seconds() - timeo / HZ;
 			paws_reject = tcp_paws_reject(&tmp_opt, th->rst);
 		}
 	}

@@ -629,8 +634,9 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 		    !inet_rtx_syn_ack(sk, req)) {
 			unsigned long expires = jiffies;
 
-			expires += min(TCP_TIMEOUT_INIT << req->num_timeout,
-				       TCP_RTO_MAX);
+			expires += min_t(unsigned long,
+					 (unsigned long)req->timeout << req->num_timeout,
+					 TCP_RTO_MAX);
 			if (!fastopen)
 				mod_timer_pending(&req->rsk_timer, expires);
 			else