Re: [PATCH v2 04/22] vfio/pci: Register a file handler with Live Update Orchestrator

[David Matlack]

On 2026-02-25 02:33 PM, Alex Williamson wrote:
> On Thu, 29 Jan 2026 21:24:51 +0000
> David Matlack <dmatlack@xxxxxxxxxx> wrote:

> > +int __init vfio_pci_liveupdate_init(void)
> > +{
> > +	if (!liveupdate_enabled())
> > +		return 0;
> > +
> > +	return liveupdate_register_file_handler(&vfio_pci_liveupdate_fh);
> > +}
> 
> liveupdate_register_file_handler() "pins" vfio-pci with a
> try_module_get().  Since this is done in our module_init function and
> unregister occurs in our module_exit function, rather than relative
> to any actual device binding or usage, this means vfio-pci CANNOT be
> unloaded.  That seems bad.  Thanks,

Good point. So a better approach that would allow vfio-pci to be
unloaded would be to register the file handler when the number of
devices bound to vfio-pci goes from 0->1 and then unregister on 1->0.