netdev - Re: [PATCH net] tcp: enable per-socket rate limiting of all 'challenge acks'

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Date:	Fri, 15 Jul 2016 09:39:43 -0400
From:	Neal Cardwell <ncardwell@...gle.com>
To:	Jason Baron <jbaron@...mai.com>
Cc:	Eric Dumazet <edumazet@...gle.com>,
	David Miller <davem@...emloft.net>,
	Netdev <netdev@...r.kernel.org>,
	Yuchung Cheng <ycheng@...gle.com>, Yue Cao <ycao009@....edu>
Subject: Re: [PATCH net] tcp: enable per-socket rate limiting of all
 'challenge acks'

On Thu, Jul 14, 2016 at 11:38 AM, Jason Baron <jbaron@...mai.com> wrote:
>
> From: Jason Baron <jbaron@...mai.com>
>
> The per-socket rate limit for 'challenge acks' was introduced in the
> context of limiting ack loops:
>
> commit f2b2c582e824 ("tcp: mitigate ACK loops for connections as tcp_sock")
>
> And I think it can be extended to rate limit all 'challenge acks' on a
> per-socket basis.
>
> Since we have the global tcp_challenge_ack_limit, this patch allows for
> tcp_challenge_ack_limit to be set to a large value and effectively rely on
> the per-socket limit, or set tcp_challenge_ack_limit to a lower value and
> still prevents a single connections from consuming the entire challenge ack
> quota.
>
> It further moves in the direction of eliminating the global limit at some
> point, as Eric Dumazet has suggested. This a follow-up to:
> Subject: tcp: make challenge acks less predictable
>
> Cc: Eric Dumazet <edumazet@...gle.com>
> Cc: David S. Miller <davem@...emloft.net>
> Cc: Neal Cardwell <ncardwell@...gle.com>
> Cc: Yuchung Cheng <ycheng@...gle.com>
> Cc: Yue Cao <ycao009@....edu>
> Signed-off-by: Jason Baron <jbaron@...mai.com>
> ---
>  net/ipv4/tcp_input.c | 39 ++++++++++++++++++++++-----------------
>  1 file changed, 22 insertions(+), 17 deletions(-)

Sounds good to me.

 Acked-by: Neal Cardwell <ncardwell@...gle.com>

thanks,
neal