netdev - Re: [PATCH net] tcp: do not rearm RTO when future data are sacked

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1382644694.7572.61.camel@edumazet-glaptop.roam.corp.google.com>
Date:	Thu, 24 Oct 2013 12:58:14 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Yuchung Cheng <ycheng@...gle.com>
Cc:	davem@...emloft.net, ncardwell@...gle.com, edumazet@...gle.com,
	brakmo@...gle.com, netdev@...r.kernel.org
Subject: Re: [PATCH net] tcp: do not rearm RTO when future data are sacked

On Thu, 2013-10-24 at 08:59 -0700, Yuchung Cheng wrote:
> Patch ed08495c3 "tcp: use RTT from SACK for RTO" always re-arms RTO upon
> obtaining a RTT sample from newly sacked data.
> 
> But technically RTO should only be re-armed when the data sent before
> the last (re)transmission of write queue head are (s)acked. Otherwise
> the RTO may continue to extend during loss recovery on data sent
> in the future.
> 
> Note that RTTs from ACK or timestamps do not have this problem, as the RTT
> source must be from data sent before.
> 
> The new RTO re-arm policy is
> 1) Always re-arm RTO if SND.UNA is advanced
> 2) Re-arm RTO if sack RTT is available, provided the sacked data was
>    sent before the last time write_queue_head was sent.
> 
> Signed-off-by: Larry Brakmo <brakmo@...gle.com>
> Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
> ---
>  net/ipv4/tcp_input.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)

Acked-by: Eric Dumazet <edumazet@...gle.com>


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html