netdev - Re: [PATCH net] tcp: change txhash on SYN-data timeout

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Message-Id: <20190110.135633.11196592386864849.davem@davemloft.net>
Date:   Thu, 10 Jan 2019 13:56:33 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     ycheng@...gle.com
Cc:     edumazet@...gle.com, netdev@...r.kernel.org, ncardwell@...gle.com
Subject: Re: [PATCH net] tcp: change txhash on SYN-data timeout

From: Yuchung Cheng <ycheng@...gle.com>
Date: Tue,  8 Jan 2019 18:14:28 -0800

> Previously upon SYN timeouts the sender recomputes the txhash to
> try a different path. However this does not apply on the initial
> timeout of SYN-data (active Fast Open). Therefore an active IPv6
> Fast Open connection may incur one second RTO penalty to take on
> a new path after the second SYN retransmission uses a new flow label.
> 
> This patch removes this undesirable behavior so Fast Open changes
> the flow label just like the regular connections. This also helps
> avoid falsely disabling Fast Open on the sender which triggers
> after two consecutive SYN timeouts on Fast Open.
> 
> Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
> Reviewed-by: Neal Cardwell <ncardwell@...gle.com>

Applied and queued up for -stable, thanks!