Re: [PATCH iproute2] ip link: add sub-command to view and change DSA master

From: Florian Fainelli <f.fainelli@gmail.com>
To: Vladimir Oltean <vladimir.oltean@nxp.com>,
	Stephen Hemminger <stephen@networkplumber.org>
Cc: David Ahern <dsahern@kernel.org>, Andrew Lunn <andrew@lunn.ch>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Vivien Didelot <vivien.didelot@gmail.com>
Subject: Re: [PATCH iproute2] ip link: add sub-command to view and change DSA master
Date: Thu, 8 Sep 2022 09:35:03 -0700	[thread overview]
Message-ID: <857e2dd4-cbc6-613c-c8e1-b3ff5d13dc47@gmail.com> (raw)
In-Reply-To: <20220908161104.rcgl3k465ork5vwv@skbuf>

On 9/8/2022 9:11 AM, Vladimir Oltean wrote:
> On Thu, Sep 08, 2022 at 07:25:19AM -0700, Stephen Hemminger wrote:
>> On Thu, 8 Sep 2022 08:08:23 -0600 David Ahern <dsahern@kernel.org> wrote:
>>>> Proposing any alternative naming raises the question how far you want to
>>>> go with the alternative name. No user of DSA knows the "conduit interface"
>>>> or "management port" or whatnot by any other name except "DSA master".
>>>> What do we do about the user-visible Documentation/networking/dsa/configuration.rst,
>>>> which clearly and consistently uses the 'master' name everywhere?
>>>> Do we replace 'master' with something else and act as if it was never
>>>> named 'master' in the first place? Do we introduce IFLA_DSA_MGMT_PORT as
>>>> UAPI and explain in the documentation "oh yeah, that's how you change
>>>> the DSA master"? "Ahh ok, why didn't you just call it IFLA_DSA_MASTER
>>>> then?" "Well...."
>>>>
>>>> Also, what about the code in net/dsa/*.c and drivers/net/dsa/, do we
>>>> also change that to reflect the new terminology, or do we just have
>>>> documentation stating one thing and the code another?
>>>>
>>>> At this stage, I'm much more likely to circumvent all of this, and avoid
>>>> triggering anyone by making a writable IFLA_LINK be the mechanism through
>>>> which we change the DSA master.
>>>
>>> IMHO, 'master' should be an allowed option giving the precedence of
>>> existing code and existing terminology. An alternative keyword can be
>>> used for those that want to avoid use of 'master' in scripts. vrf is an
>>> example of this -- you can specify 'vrf <device>' as a keyword instead
>>> of 'master <vrf>'
>>
>> Agreed, just wanted to start discussion of alternative wording.
> 
> So are we or are we not in the clear with IFLA_DSA_MASTER and
> "ip link set ... type dsa master ..."? What does being in the clear even
> mean technically, and where can I find more details about the policy
> which you just mentioned? Like is it optional or mandatory, was there
> any public debate surrounding the motivation for flagging some words,
> how is it enforced, are there official exceptions, etc?

The "bonding" driver topic has some good context:

https://lkml.iu.edu/hypermail/linux/kernel/2010.0/02186.html
-- 
Florian