Re: [PATCH] spi: bcm2835: do not unregister controller in shutdown handler

Jason Gunthorpe
2021-10-04T18:37:50Z

On Mon, Oct 04, 2021 at 08:30:52PM +0200, Lino Sanfilippo wrote:
> On 04.10.21 at 17:44, Jason Gunthorpe wrote:
>
> >
> > Well, that is up to the driver implementing this. It looks like device
> > shutdown is called before the userspace is all nuked so yes,
> > concurrency with userspace is a possible concern here.
> >
>
> So the TPM driver has to handle remove() after shutdown() anyway, right?
> Because even if not caused by the BCM2835 drivers controller unregistration
> something else could unload the module and the problem (NULL pointer access)
> would be the same.

Technically yes, remove shouldn't crash in this ordering - but it
should be difficult for remove to be called after shutdown in any
normal system.

Jason