In some situations tcp_send_loss_probe() can realize that it's unable
to send a loss probe (TLP), and falls back to calling tcp_rearm_rto()
to schedule an RTO timer. In such cases, sometimes tcp_rearm_rto()
realizes that the RTO was eligible to fire immediately or at some
point in the past (delta_us <= 0). Previously in such cases
tcp_rearm_rto() was scheduling such "overdue" RTOs to happen at now +
icsk_rto, which caused needless delays of hundreds of milliseconds
(and non-linear behavior that made reproducible testing
difficult). This commit changes the logic to schedule "overdue" RTOs
ASAP, rather than at now + icsk_rto.
Suggested-by: Yuchung Cheng <ych...@google.com>
Signed-off-by: Neal Cardwell <ncardw...@google.com>
Signed-off-by: Yuchung Cheng <ych...@google.com>
Signed-off-by: Eric Dumazet <eduma...@google.com>
---
net/ipv4/tcp_input.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 53de1424c13c..bab7f0493098 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3009,8 +3009,7 @@ void tcp_rearm_rto(struct sock *sk)
/* delta_us may not be positive if the socket is locked
* when the retrans timer fires and is rescheduled.
*/
- if (delta_us > 0)
- rto = usecs_to_jiffies(delta_us);
+ rto = usecs_to_jiffies(max_t(int, delta_us, 1));
}
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, rto,
TCP_RTO_MAX);
--
2.14.1.480.gb18f417b89-goog
