2 files changed, 25 insertions, 4 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 54f212ce8aaf..e5319495f15e 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1252,6 +1252,24 @@ static inline struct sk_buff *tcp_write_queue_prev(struct sock *sk, struct sk_bu
 #define tcp_for_write_queue_from_safe(skb, tmp, sk)			\
 	skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
 
+static inline bool retransmits_timed_out(const struct sock *sk,
+					 unsigned int boundary)
+{
+	int limit, K;
+	if (!inet_csk(sk)->icsk_retransmits)
+		return false;
+
+	K = ilog2(TCP_RTO_MAX/TCP_RTO_MIN);
+
+	if (boundary <= K)
+		limit = ((2 << boundary) - 1) * TCP_RTO_MIN;
+	else
+		limit = ((2 << K) - 1) * TCP_RTO_MIN +
+			(boundary - K) * TCP_RTO_MAX;
+
+	return (tcp_time_stamp - tcp_sk(sk)->retrans_stamp) >= limit;
+}
+
 static inline struct sk_buff *tcp_send_head(struct sock *sk)
 {
 	return sk->sk_send_head;
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 408fa4b7b9ba..cdb2ca7684d4 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -137,13 +137,14 @@ static int tcp_write_timeout(struct sock *sk)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	int retry_until;
+	bool do_reset;
 
 	if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
 		if (icsk->icsk_retransmits)
 			dst_negative_advice(&sk->sk_dst_cache);
 		retry_until = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
 	} else {
-		if (icsk->icsk_retransmits >= sysctl_tcp_retries1) {
+		if (retransmits_timed_out(sk, sysctl_tcp_retries1)) {
 			/* Black hole detection */
 			tcp_mtu_probing(icsk, sk);
 
@@ -155,13 +156,15 @@ static int tcp_write_timeout(struct sock *sk)
 			const int alive = (icsk->icsk_rto < TCP_RTO_MAX);
 
 			retry_until = tcp_orphan_retries(sk, alive);
+			do_reset = alive ||
+				   !retransmits_timed_out(sk, retry_until);
 
-			if (tcp_out_of_resources(sk, alive || icsk->icsk_retransmits < retry_until))
+			if (tcp_out_of_resources(sk, do_reset))
 				return 1;
 		}
 	}
 
-	if (icsk->icsk_retransmits >= retry_until) {
+	if (retransmits_timed_out(sk, retry_until)) {
 		/* Has it gone just too far? */
 		tcp_write_err(sk);
 		return 1;
@@ -385,7 +388,7 @@ void tcp_retransmit_timer(struct sock *sk)
 out_reset_timer:
 	icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX);
 	inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, TCP_RTO_MAX);
-	if (icsk->icsk_retransmits > sysctl_tcp_retries1)
+	if (retransmits_timed_out(sk, sysctl_tcp_retries1 + 1))
 		__sk_dst_reset(sk);
 
 out:;