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

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Message-ID: <aKXzzxgsIQWYFQ9l@mozart.vkv.me>
Date: Wed, 20 Aug 2025 09:11:59 -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 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.

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.

Thanks,
Calvin