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authorNeal Cardwell <ncardwell@google.com>2017-08-16 17:53:36 -0400
committerDavid S. Miller <davem@davemloft.net>2017-08-18 16:07:43 -0700
commitcdbeb633ca71a02b7b63bfeb94994bf4e1a0b894 (patch)
tree96d187e3d5f38c8fcb9045fb1ff323ad8164b021 /net/ipv4
parentbc3aae2bbac46dd894c89db5d5e98f7f0ef9e205 (diff)
downloadlinux-cdbeb633ca71a02b7b63bfeb94994bf4e1a0b894.tar.bz2
tcp: when rearming RTO, if RTO time is in past then fire RTO ASAP
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. Fixes: 6ba8a3b19e76 ("tcp: Tail loss probe (TLP)") Suggested-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/tcp_input.c3
1 files changed, 1 insertions, 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);