Subject: Re: [PATCH] veth: replace iflink by a dedicated symlink in sysfs

From: Vincent Bernat <[email-masked]>
Date: Sat, 22 Aug 2015 22:51:01 +0200

❦ 20 août 2015 14:07 -0700, David Miller <[email-masked]> :

>>>> I also don't know what is the best way to handle this. veth advertises
>>>> its peer via IFLA_LINK since 4.1, so it's too late to change it for
>>>> this
>>>> release.
>>>
>>> Apparently we need to pick our poison. Either way, we break something.
>> Sure. I would prefer to have the same mechanism in all version, but I
>> can live with the other solution.
>> 
>> David, any thoughts about this?
>
> You can't break the 4.1 semantics, it's in a released kernel and people
> _ARE_ using it.

I had a look at what other kind of daemons may exploit the pre-4.1
semantics (of not having an infinite loop when following iflink) and
failed to find any other users than "lldpd". Other LLDP daemons (lldpad,
ladvd, openlldpd) have other ways to find the lower interface. I would
also have thought that NetSNMP would use it to implement ifStackTable
but it doesn't in fact implement this table.
-- 
It were not best that we should all think alike; it is difference of opinion
that makes horse-races.
		-- Mark Twain, "Pudd'nhead Wilson's Calendar"