linux-kernel - Re: [PATCH net-next] bridge: mrp: Implement LC mode for MRP

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Message-ID: <13cef7c2-cacc-2c24-c0d5-e462b0e3b4df@nvidia.com>
Date:   Mon, 23 Nov 2020 16:25:53 +0200
From:   Nikolay Aleksandrov <nikolay@...dia.com>
To:     Horatiu Vultur <horatiu.vultur@...rochip.com>
CC:     <roopa@...dia.com>, <davem@...emloft.net>, <kuba@...nel.org>,
        <linux-kernel@...r.kernel.org>,
        <bridge@...ts.linux-foundation.org>, <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] bridge: mrp: Implement LC mode for MRP

On 23/11/2020 14:31, Horatiu Vultur wrote:
> The 11/23/2020 14:13, Nikolay Aleksandrov wrote:
>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>
>> On 23/11/2020 13:14, Horatiu Vultur wrote:
>>> Extend MRP to support LC mode(link check) for the interconnect port.
>>> This applies only to the interconnect ring.
>>>
>>> Opposite to RC mode(ring check) the LC mode is using CFM frames to
>>> detect when the link goes up or down and based on that the userspace
>>> will need to react.
>>> One advantage of the LC mode over RC mode is that there will be fewer
>>> frames in the normal rings. Because RC mode generates InTest on all
>>> ports while LC mode sends CFM frame only on the interconnect port.
>>>
>>> All 4 nodes part of the interconnect ring needs to have the same mode.
>>> And it is not possible to have running LC and RC mode at the same time
>>> on a node.
>>>
>>> Whenever the MIM starts it needs to detect the status of the other 3
>>> nodes in the interconnect ring so it would send a frame called
>>> InLinkStatus, on which the clients needs to reply with their link
>>> status.
>>>
>>> This patch adds the frame header for the frame InLinkStatus and
>>> extends existing rules on how to forward this frame.
>>>
>>> Signed-off-by: Horatiu Vultur <horatiu.vultur@...rochip.com>
>>> ---
>>>  include/uapi/linux/mrp_bridge.h |  7 +++++++
>>>  net/bridge/br_mrp.c             | 18 +++++++++++++++---
>>>  2 files changed, 22 insertions(+), 3 deletions(-)
>>>
>>
>> Hi Horatiu,
>> The patch looks good overall, just one question below.
> 
> Hi Nik,
> 
> Thanks for taking time to review the patch.
> 
>>
>>> diff --git a/include/uapi/linux/mrp_bridge.h b/include/uapi/linux/mrp_bridge.h
>>> index 6aeb13ef0b1e..450f6941a5a1 100644
>>> --- a/include/uapi/linux/mrp_bridge.h
>>> +++ b/include/uapi/linux/mrp_bridge.h
>>> @@ -61,6 +61,7 @@ enum br_mrp_tlv_header_type {
>>>       BR_MRP_TLV_HEADER_IN_TOPO = 0x7,
>>>       BR_MRP_TLV_HEADER_IN_LINK_DOWN = 0x8,
>>>       BR_MRP_TLV_HEADER_IN_LINK_UP = 0x9,
>>> +     BR_MRP_TLV_HEADER_IN_LINK_STATUS = 0xa,
>>>       BR_MRP_TLV_HEADER_OPTION = 0x7f,
>>>  };
>>>
>>> @@ -156,4 +157,10 @@ struct br_mrp_in_link_hdr {
>>>       __be16 interval;
>>>  };
>>>
>>> +struct br_mrp_in_link_status_hdr {
>>> +     __u8 sa[ETH_ALEN];
>>> +     __be16 port_role;
>>> +     __be16 id;
>>> +};
>>> +
>>
>> I didn't see this struct used anywhere, am I missing anything?
> 
> Yes, you are right, the struct is not used any. But I put it there as I
> put the other frame types for MRP.
> 

I see, we don't usually add unused code. The patch is fine as-is and since
this is already the case for other MRP parts I'm not strictly against it, so:

Acked-by: Nikolay Aleksandrov <nikolay@...dia.com>

If Jakub decides to adhere to that rule you can keep my acked-by and just remove
the struct for v2.

Thanks,
 Nik