tcp: don't extend RTO on failed loss probe attempts

If TLP was unable to send a probe, it extended the RTO to
now + icsk_rto. But extending the RTO makes little sense
if no TLP probe went out. With this commit, instead of
extending the RTO we re-arm it relative to the transmit time
of the write queue head.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 7d1efa7..78fc89c 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2275,13 +2275,12 @@ void tcp_send_loss_probe(struct sock *sk)
                tp->tlp_high_seq = tp->snd_nxt;
 
 rearm_timer:
-       inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
-                                 inet_csk(sk)->icsk_rto,
-                                 TCP_RTO_MAX);
-
-       if (likely(!err))
-               NET_INC_STATS_BH(sock_net(sk),
-                                LINUX_MIB_TCPLOSSPROBES);
+       if (likely(!err)) {
+               NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSSPROBES);
+               /* Reset s.t. tcp_rearm_rto will restart timer from now */
+               inet_csk(sk)->icsk_pending = 0;
+       }
+       tcp_rearm_rto(sk);
 }
 
 /* Push out any pending frames which were held back due to