linux-kernel - Re: [PATCH net] i40e: Prevent unwanted interface name changes

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Message-ID: <aKZVm-0iiMsUfexu@mozart.vkv.me>
Date: Wed, 20 Aug 2025 16:09:15 -0700
From: Calvin Owens <calvin@...nvd.org>
To: Przemek Kitszel <przemyslaw.kitszel@...el.com>
Cc: Michal Schmidt <mschmidt@...hat.com>, netdev@...r.kernel.org,
	Tony Nguyen <anthony.l.nguyen@...el.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Jedrzej Jagielski <jedrzej.jagielski@...el.com>,
	Ivan Vecera <ivecera@...hat.com>, intel-wired-lan@...ts.osuosl.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] i40e: Prevent unwanted interface name changes

On Wednesday 08/20 at 09:11 -0700, Calvin Owens wrote:
> On Wednesday 08/20 at 11:41 +0200, Przemek Kitszel wrote:
> > On 8/20/25 08:42, Michal Schmidt wrote:
> > > On Wed, Aug 20, 2025 at 6:30 AM Calvin Owens <calvin@...nvd.org> wrote:
> > > > The same naming regression which was reported in ixgbe and fixed in
> > > > commit e67a0bc3ed4f ("ixgbe: prevent from unwanted interface name
> > > > changes") still exists in i40e.
> > > > 
> > > > Fix i40e by setting the same flag, added in commit c5ec7f49b480
> > > > ("devlink: let driver opt out of automatic phys_port_name generation").
> > > > 
> > > > Fixes: 9e479d64dc58 ("i40e: Add initial devlink support")
> > > 
> > > But this one's almost two years old. By now, there may be more users
> > > relying on the new name than on the old one.
> > > Michal
> > > 
> > 
> > And, more importantly, noone was complaining on the new name ;)
> 
> I'm just guessing with the Fixes tag, I didn't actually go back and try
> to figure out when it broke. Let me double check, it would certainly
> make more sense if it broke more recently.

I actually checked, it really goes back that far.

> But there are a lot of reasons I still think it should be fixed:
> 
> 	1) I have ixgbe and i40e cards in one machine, the mis-match
> 	   between the interface naming pattern is irritating. Can't we
> 	   at least be consistent within the same manufacturer?
> 
> 	2) The new names have zero real value: "enp2s0fX" vs
> 	   "enp2s0fXnpX", the "npX" prefix is entirely redundant for
> 	   this i40e card. Is there some case where it can have meaning?
> 	   I apologize if I'm glossing over something here, but it looks
> 	   entirely pointless. If it solved some real problem, I'd be a
> 	   lot more amenable to it.
> 
> 	3) It's a userspace ABI regression which causes previously
> 	   working servers to be unable to connect to the network after
> 	   a simple kernel upgrade.
> 
> And, at the end of the day, it *is* a userspace ABI regression. If it
> matters enough in ixgbe to warrant a *second* userspace ABI regression
> to fix it, I think it warrants that in i40e too.

I just want to be clear: I'm not here to whine at you all about having
to spend ten minutes fixing some configuration files. My goal is to save
a bunch other people the trouble of doing it over the next five years,
if it's not too late.

If it is true the majority of i40e users have converted, than yes, this
should stay the way it is. I'm *very* skeptical that would be true only
19 months after the release... but I don't have any real data to argue
either way.

> Thanks,
> Calvin