Subject: Re: linux-next: build failure after merge of the usb tree

From: Matthias Kaehlcke <[email-masked]>
Date: Mon, 2 May 2022 10:09:25 -0700

On Mon, May 02, 2022 at 01:40:45PM +0200, Greg KH wrote:
> On Mon, May 02, 2022 at 09:07:28PM +1000, Stephen Rothwell wrote:
> > Hi all,
> > 
> > After merging the usb tree, today's linux-next build (x86_64
> > modules_install) failed like this:
> > 
> > depmod: ERROR: Cycle detected: usbcore -> onboard_usb_hub -> usbcore
> > depmod: ERROR: Found 2 modules in dependency cycles!
> > 
> > Caused by commit
> > 
> >   c40b62216c1a ("usb: core: hcd: Create platform devices for onboard hubs in probe()")
> > 
> > I have reverted that commit for today.
> 
> argh, I thought the build issues were fixed :(

Sorry about that :(

The *build* issues were actually fixed, however I did not try
modules_install ...

> I'll go revert that series from my tree later today, thanks for the
> report.

I think the dependency situation can only be resolved by linking
onboard_hub_create/destroy_pdevs() into the USB core module. My initial
idea was to build them into the kernel binary, however that doesn't
work because onboard_hub_create_pdevs() calls usb_of_get_device_node(),
which is part of the core module when CONFIG_USB=m. The two function
are relatively lightweight and don't depend on internals of the
onboard_usb_hub driver (besides the device id table) so linking them
into the core module doesn't seem too ugly.