netdev - Re: [RFC] r8152: pass through needs to be singular

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Message-ID: <34f7cb15-91e8-e92c-7dcd-f5b28724df92@suse.com>
Date:   Tue, 2 Aug 2022 12:52:05 +0200
From:   Oliver Neukum <oneukum@...e.com>
To:     Andrew Lunn <andrew@...n.ch>, Oliver Neukum <oneukum@...e.com>
Cc:     hayeswang@...ltek.com, netdev@...r.kernel.org
Subject: Re: [RFC] r8152: pass through needs to be singular



On 29.07.22 00:11, Andrew Lunn wrote:
> On Thu, Jul 28, 2022 at 09:18:51PM +0200, Oliver Neukum wrote:
>> If multiple devices are connected only one of them
>> is allowed to get the pass through MAC
> 
> Is that true? Ethernet switches often use the same MAC address on
> multiple ports. It is not inherently broken to have the same MAC
> address on multiple interfaces.

Well, yes, but for a host to assigning the same MAC by default
is a bug. The whole point of MACs is kind of that they be unique.
For the same reason I fixed usbnet to not hand out the same
random address. In theory I have broken setups which relied on
people reconnecting a device getting the same MAC.

> We know this implementation of pass through it very broken, but
> unfortunately, it is there, and we have to follow the normal
> regression rules, even if we really would like to throw it all out.

True. Nevertheless, do we really want to say that we dislike a design
so much that we are not fixing bugs?

> What exactly is your problem which you are trying to fix? 
Adressing the comment Hayes made when reset_resume() was fixed
from a deadlock, that it still assigns wrong MACs. I feel that
before I fix keeping the correct address I better make sure the
MAC is sane in the first place.

	Regards
		Oliver