1 files changed, 4 insertions, 2 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index b5fa3c19afee..0faacf9c419d 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1035,8 +1035,10 @@ static inline int tcp_nagle_test(struct tcp_sock *tp, struct sk_buff *skb,
         if (nonagle & TCP_NAGLE_PUSH)
                 return 1;
 
-        /* Don't use the nagle rule for urgent data (or for the final FIN).  */
-        if (tp->urg_mode ||
+        /* Don't use the nagle rule for urgent data (or for the final FIN).
+         * Nagle can be ignored during F-RTO too (see RFC4138).
+         */
+        if (tp->urg_mode || (tp->frto_counter == 2) ||
             (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN))
                 return 1;