netdev - Re: [PATCH V1 net-next 5/8] net: ena: add support for traffic mirroring

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Message-ID: <20200709132200.60db5881@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Thu, 9 Jul 2020 13:22:00 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     <akiyano@...zon.com>
Cc:     <davem@...emloft.net>, <netdev@...r.kernel.org>, <dwmw@...zon.com>,
        <zorik@...zon.com>, <matua@...zon.com>, <saeedb@...zon.com>,
        <msw@...zon.com>, <aliguori@...zon.com>, <nafea@...zon.com>,
        <gtzalik@...zon.com>, <netanel@...zon.com>, <alisaidi@...zon.com>,
        <benh@...zon.com>, <ndagan@...zon.com>, <shayagr@...zon.com>,
        <sameehj@...zon.com>
Subject: Re: [PATCH V1 net-next 5/8] net: ena: add support for traffic
 mirroring

On Thu, 9 Jul 2020 22:05:00 +0300 akiyano@...zon.com wrote:
> From: Arthur Kiyanovski <akiyano@...zon.com>
> 
> Add support for traffic mirroring, where the hardware reads the
> buffer from the instance memory directly.
> 
> Traffic Mirroring needs access to the rx buffers in the instance.
> To have this access, this patch:
> 1. Changes the code to map and unmap the rx buffers bidirectionally.
> 2. Enables the relevant bit in driver_supported_features to indicate
>    to the FW that this driver supports traffic mirroring.
> 
> Signed-off-by: Arthur Kiyanovski <akiyano@...zon.com>

Any more information? You map rx buffers bidirectionally, doesn't mean
the instance doesn't modify the buffer causing the mirror to see a
modified frame..  Does the instance wait somehow for the mirror to be
done, or is the RX completion not generated until mirror operation is
done?