* [PATCH net] tcp: avoid setting cwnd to invalid ssthresh after cwnd reduction states
@ 2017-08-01 20:22 Yuchung Cheng
2017-08-02 9:07 ` Eric Dumazet
2017-08-02 17:51 ` David Miller
0 siblings, 2 replies; 5+ messages in thread
From: Yuchung Cheng @ 2017-08-01 20:22 UTC (permalink / raw)
To: davem; +Cc: netdev, ncardwell, edumazet, Yuchung Cheng
If the sender switches the congestion control during ECN-triggered
cwnd-reduction state (CA_CWR), upon exiting recovery cwnd is set to
the ssthresh value calculated by the previous congestion control. If
the previous congestion control is BBR that always keep ssthresh
to TCP_INIFINITE_SSTHRESH, cwnd ends up being infinite. The safe
step is to avoid assigning invalid ssthresh value when recovery ends.
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
---
net/ipv4/tcp_input.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 2920e0cb09f8..dad026fcfd09 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2520,8 +2520,8 @@ static inline void tcp_end_cwnd_reduction(struct sock *sk)
return;
/* Reset cwnd to ssthresh in CWR or Recovery (unless it's undone) */
- if (inet_csk(sk)->icsk_ca_state == TCP_CA_CWR ||
- (tp->undo_marker && tp->snd_ssthresh < TCP_INFINITE_SSTHRESH)) {
+ if (tp->snd_ssthresh < TCP_INFINITE_SSTHRESH &&
+ (inet_csk(sk)->icsk_ca_state == TCP_CA_CWR || tp->undo_marker)) {
tp->snd_cwnd = tp->snd_ssthresh;
tp->snd_cwnd_stamp = tcp_jiffies32;
}
--
2.14.0.rc1.383.gd1ce394fe2-goog
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH net] tcp: avoid setting cwnd to invalid ssthresh after cwnd reduction states
2017-08-01 20:22 [PATCH net] tcp: avoid setting cwnd to invalid ssthresh after cwnd reduction states Yuchung Cheng
@ 2017-08-02 9:07 ` Eric Dumazet
2017-08-02 17:51 ` David Miller
1 sibling, 0 replies; 5+ messages in thread
From: Eric Dumazet @ 2017-08-02 9:07 UTC (permalink / raw)
To: Yuchung Cheng; +Cc: davem, netdev, ncardwell, edumazet
On Tue, 2017-08-01 at 13:22 -0700, Yuchung Cheng wrote:
> If the sender switches the congestion control during ECN-triggered
> cwnd-reduction state (CA_CWR), upon exiting recovery cwnd is set to
> the ssthresh value calculated by the previous congestion control. If
> the previous congestion control is BBR that always keep ssthresh
> to TCP_INIFINITE_SSTHRESH, cwnd ends up being infinite. The safe
> step is to avoid assigning invalid ssthresh value when recovery ends.
>
> Signed-off-by: Yuchung Cheng <ycheng@google.com>
> Signed-off-by: Neal Cardwell <ncardwell@google.com>
> ---
> net/ipv4/tcp_input.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
Acked-by: Eric Dumazet <edumazet@google.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH net] tcp: avoid setting cwnd to invalid ssthresh after cwnd reduction states
2017-08-01 20:22 [PATCH net] tcp: avoid setting cwnd to invalid ssthresh after cwnd reduction states Yuchung Cheng
2017-08-02 9:07 ` Eric Dumazet
@ 2017-08-02 17:51 ` David Miller
2017-08-02 17:58 ` Yuchung Cheng
1 sibling, 1 reply; 5+ messages in thread
From: David Miller @ 2017-08-02 17:51 UTC (permalink / raw)
To: ycheng; +Cc: netdev, ncardwell, edumazet
From: Yuchung Cheng <ycheng@google.com>
Date: Tue, 1 Aug 2017 13:22:32 -0700
> If the sender switches the congestion control during ECN-triggered
> cwnd-reduction state (CA_CWR), upon exiting recovery cwnd is set to
> the ssthresh value calculated by the previous congestion control. If
> the previous congestion control is BBR that always keep ssthresh
> to TCP_INIFINITE_SSTHRESH, cwnd ends up being infinite. The safe
> step is to avoid assigning invalid ssthresh value when recovery ends.
>
> Signed-off-by: Yuchung Cheng <ycheng@google.com>
> Signed-off-by: Neal Cardwell <ncardwell@google.com>
Applied, thanks.
Is this a -stable candidate?
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH net] tcp: avoid setting cwnd to invalid ssthresh after cwnd reduction states
2017-08-02 17:51 ` David Miller
@ 2017-08-02 17:58 ` Yuchung Cheng
2017-08-03 16:30 ` David Miller
0 siblings, 1 reply; 5+ messages in thread
From: Yuchung Cheng @ 2017-08-02 17:58 UTC (permalink / raw)
To: David Miller; +Cc: netdev, Neal Cardwell, Eric Dumazet
On Wed, Aug 2, 2017 at 10:51 AM, David Miller <davem@davemloft.net> wrote:
>
> From: Yuchung Cheng <ycheng@google.com>
> Date: Tue, 1 Aug 2017 13:22:32 -0700
>
> > If the sender switches the congestion control during ECN-triggered
> > cwnd-reduction state (CA_CWR), upon exiting recovery cwnd is set to
> > the ssthresh value calculated by the previous congestion control. If
> > the previous congestion control is BBR that always keep ssthresh
> > to TCP_INIFINITE_SSTHRESH, cwnd ends up being infinite. The safe
> > step is to avoid assigning invalid ssthresh value when recovery ends.
> >
> > Signed-off-by: Yuchung Cheng <ycheng@google.com>
> > Signed-off-by: Neal Cardwell <ncardwell@google.com>
>
> Applied, thanks.
>
> Is this a -stable candidate?
Yes it is. Thanks!
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH net] tcp: avoid setting cwnd to invalid ssthresh after cwnd reduction states
2017-08-02 17:58 ` Yuchung Cheng
@ 2017-08-03 16:30 ` David Miller
0 siblings, 0 replies; 5+ messages in thread
From: David Miller @ 2017-08-03 16:30 UTC (permalink / raw)
To: ycheng; +Cc: netdev, ncardwell, edumazet
From: Yuchung Cheng <ycheng@google.com>
Date: Wed, 2 Aug 2017 10:58:54 -0700
> On Wed, Aug 2, 2017 at 10:51 AM, David Miller <davem@davemloft.net> wrote:
>>
>> From: Yuchung Cheng <ycheng@google.com>
>> Date: Tue, 1 Aug 2017 13:22:32 -0700
>>
>> > If the sender switches the congestion control during ECN-triggered
>> > cwnd-reduction state (CA_CWR), upon exiting recovery cwnd is set to
>> > the ssthresh value calculated by the previous congestion control. If
>> > the previous congestion control is BBR that always keep ssthresh
>> > to TCP_INIFINITE_SSTHRESH, cwnd ends up being infinite. The safe
>> > step is to avoid assigning invalid ssthresh value when recovery ends.
>> >
>> > Signed-off-by: Yuchung Cheng <ycheng@google.com>
>> > Signed-off-by: Neal Cardwell <ncardwell@google.com>
>>
>> Applied, thanks.
>>
>> Is this a -stable candidate?
>
> Yes it is. Thanks!
Great, queued up.
^ permalink raw reply [flat|nested] 5+ messages in thread
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2017-08-01 20:22 [PATCH net] tcp: avoid setting cwnd to invalid ssthresh after cwnd reduction states Yuchung Cheng
2017-08-02 9:07 ` Eric Dumazet
2017-08-02 17:51 ` David Miller
2017-08-02 17:58 ` Yuchung Cheng
2017-08-03 16:30 ` David Miller
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