Re: [PATCH v3 0/5] rust: miscdevice: Provide sample driver using the new MiscDevice bindings

Greg KH
2024-12-06T08:11:34Z

On Fri, Dec 06, 2024 at 07:44:43AM +0000, Lee Jones wrote:
> On Fri, 06 Dec 2024, Greg KH wrote:
>
> > On Thu, Dec 05, 2024 at 04:25:17PM +0000, Lee Jones wrote:
> > > It has been suggested that the driver should use dev_info() instead of
> > > pr_info() however there is currently no scaffolding to successfully pull
> > > a 'struct device' out from driver data post register(). This is being
> > > worked on and we will convert this over in due course.
> >
> > But the miscdevice.rs change provides this to you, right? Or if not,
> > why not?
>
> This does allow us to pull the 'struct device *` out from `struct
> miscdevice`; however, since this resides in MiscDeviceRegistration,
> which we lose access to after .init, we have no means to call it.
>
> Alice is going to work on a way to use ThisModule to get the
> MiscDeviceRegistration reference back from anywhere in the module. Until
> that piece lands, we can't call MiscDeviceRegistration::device() outside
> of RustMiscDeviceModule.

That seems crazy, as ThisModule shouldn't be dealing with a static misc
device, what happens for dynamically created ones like all
normal/sane/non-example drivers do? This should "just" be a dynamic
object that is NOT tied to the module object, or worst case, a "static"
structure that is tied to the module I guess?

Anyway, I'll let you all work it out, good luck!

greg k-h