Re: [PATCH] driver core: reject devices with unregistered buses

[Johan Hovold <johan@kernel.org>]

On Wed, Apr 29, 2026 at 05:29:02PM +0200, Danilo Krummrich wrote:
> On Wed Apr 29, 2026 at 5:08 PM CEST, Johan Hovold wrote:
> > No, I'm saying that it's a bug in driver core to silently treat a device
> > that is registered before its bus as a bus-less device.
> 
> This is an argument that I can buy into, but in the previous discussion (and in
> the commit message) the whole motivation evolved around "reject devices with
> unregistered buses to catch any callers that get the ordering wrong", i.e. catch
> other people's bugs.
>
> What you are raising now is "the driver core is conflating no bus with
> unregistered bus handling". However, the commit message does not reflect that at
> all.

The commit message already explains the issue:

	Trying to register a device on a bus which has not yet been
	registered used to trigger a NULL-pointer dereference, but since
	the const bus structure rework registration instead succeeds
	without the device being added to the bus.

namely that

	 registration [...] succeeds [but] without the device being
	 added to the bus.

> Can you please adjust the commit message accordingly?

Perhaps I can add "(i.e. as if it were a bus-less device)" to stress it
more but I'm not sure it's needed.

Johan