netdev - Re: [PATCH net v2] mptcp: always include dack if possible.

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Date:   Wed, 4 Mar 2020 17:07:20 -0800 (PST)
From:   Mat Martineau <mathew.j.martineau@...ux.intel.com>
To:     Paolo Abeni <pabeni@...hat.com>
cc:     netdev@...r.kernel.org,
        Matthieu Baerts <matthieu.baerts@...sares.net>,
        "David S. Miller" <davem@...emloft.net>,
        Christoph Paasch <cpaasch@...le.com>
Subject: Re: [PATCH net v2] mptcp: always include dack if possible.


On Wed, 4 Mar 2020, Paolo Abeni wrote:

> Currently passive MPTCP socket can skip including the DACK
> option - if the peer sends data before accept() completes.
>
> The above happens because the msk 'can_ack' flag is set
> only after the accept() call.
>
> Such missing DACK option may cause - as per RFC spec -
> unwanted fallback to TCP.
>
> This change addresses the issue using the key material
> available in the current subflow, if any, to create a suitable
> dack option when msk ack seq is not yet available.
>
> v1 -> v2:
> - adavance the generated ack after the initial MPC packet
>
> Fixes: d22f4988ffec ("mptcp: process MP_CAPABLE data option")
> Signed-off-by: Paolo Abeni <pabeni@...hat.com>

Reviewed-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>

--
Mat Martineau
Intel