1 files changed, 13 insertions, 4 deletions

diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index c9c716a483e4..a4730a28b220 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -24,9 +24,6 @@
 
 int sysctl_tcp_syn_retries __read_mostly = TCP_SYN_RETRIES;
 int sysctl_tcp_synack_retries __read_mostly = TCP_SYNACK_RETRIES;
-int sysctl_tcp_keepalive_time __read_mostly = TCP_KEEPALIVE_TIME;
-int sysctl_tcp_keepalive_probes __read_mostly = TCP_KEEPALIVE_PROBES;
-int sysctl_tcp_keepalive_intvl __read_mostly = TCP_KEEPALIVE_INTVL;
 int sysctl_tcp_retries1 __read_mostly = TCP_RETR1;
 int sysctl_tcp_retries2 __read_mostly = TCP_RETR2;
 int sysctl_tcp_orphan_retries __read_mostly;
@@ -168,7 +165,7 @@ static int tcp_write_timeout(struct sock *sk)
                         dst_negative_advice(sk);
                         if (tp->syn_fastopen || tp->syn_data)
                                 tcp_fastopen_cache_set(sk, 0, NULL, true, 0);
-                        if (tp->syn_data)
+                        if (tp->syn_data && icsk->icsk_retransmits == 1)
                                 NET_INC_STATS_BH(sock_net(sk),
                                                  LINUX_MIB_TCPFASTOPENACTIVEFAIL);
                 }
@@ -176,6 +173,18 @@ static int tcp_write_timeout(struct sock *sk)
                 syn_set = true;
         } else {
                 if (retransmits_timed_out(sk, sysctl_tcp_retries1, 0, 0)) {
+                        /* Some middle-boxes may black-hole Fast Open _after_
+                         * the handshake. Therefore we conservatively disable
+                         * Fast Open on this path on recurring timeouts with
+                         * few or zero bytes acked after Fast Open.
+                         */
+                        if (tp->syn_data_acked &&
+                            tp->bytes_acked <= tp->rx_opt.mss_clamp) {
+                                tcp_fastopen_cache_set(sk, 0, NULL, true, 0);
+                                if (icsk->icsk_retransmits == sysctl_tcp_retries1)
+                                        NET_INC_STATS_BH(sock_net(sk),
+                                                         LINUX_MIB_TCPFASTOPENACTIVEFAIL);
+                        }
                         /* Black hole detection */
                         tcp_mtu_probing(icsk, sk);