linux-kernel - Re: [RFC net-next v4 0/9] net: bridge: mrp: Add support for Media Redundancy Protocol(MRP)

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Message-ID: <15dcc261-bcbb-ec67-2d8d-4208dda45b86@cumulusnetworks.com>
Date:   Mon, 30 Mar 2020 19:21:41 +0300
From:   Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:     Horatiu Vultur <horatiu.vultur@...rochip.com>, davem@...emloft.net,
        jiri@...nulli.us, ivecera@...hat.com, kuba@...nel.org,
        roopa@...ulusnetworks.com, olteanv@...il.com, andrew@...n.ch,
        UNGLinuxDriver@...rochip.com, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, bridge@...ts.linux-foundation.org
Subject: Re: [RFC net-next v4 0/9] net: bridge: mrp: Add support for Media
 Redundancy Protocol(MRP)

On 27/03/2020 11:21, Horatiu Vultur wrote:
> Media Redundancy Protocol is a data network protocol standardized by
> International Electrotechnical Commission as IEC 62439-2. It allows rings of
> Ethernet switches to overcome any single failure with recovery time faster than
> STP. It is primarily used in Industrial Ethernet applications.
> 
> Based on the previous RFC[1][2][3], the MRP state machine and all the timers
> were moved to userspace, except for the timers used to generate MRP Test frames.
> In this way the userspace doesn't know and should not know if the HW or the
> kernel will generate the MRP Test frames. The following changes were added to
> the bridge to support the MRP:
> - the existing netlink interface was extended with MRP support,
> - allow to detect when a MRP frame was received on a MRP ring port
> - allow MRP instance to forward/terminate MRP frames
> - generate MRP Test frames in case the HW doesn't have support for this
> 
> To be able to offload MRP support to HW, the switchdev API  was extend.
> 
> With these changes the userspace doesn't do the following because already the
> kernel/HW will do:
> - doesn't need to forward/terminate MRP frames
> - doesn't need to generate MRP Test frames
> - doesn't need to detect when the ring is open/closed.
> 
> The userspace application that is using the new netlink can be found here[4].
> 

Hi Horatiu,
One issue in general - some functions are used before they're defined (the switchdev
API integration ones) patch 4 vs 7 which doesn't make sense. Also I see that the BRIDGE_MRP is used
(ifdef) before it's added to the Kconfig which doesn't make much sense either.
I think you should rearrange the patches and maybe combine some of them.

Thanks,
 Nik