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> - let dev =3D faux::Registration::new(c"Kunit", None)?; > - let drm =3D UnregisteredDevice::new(dev.as_ref(), data)?; > + let reg =3D faux::Registration::new(c"Kunit", None)?; > + let fdev =3D reg.as_ref(); > + let dev =3D fdev.as_ref(); > + let drm =3D UnregisteredDevice::new(dev, data)?; > =20 > - Ok((dev, drm)) > + Ok((reg, drm)) > } > =20 > #[test] > @@ -755,7 +757,8 @@ fn vmap_io() -> Result { > #[test] > fn fail_sg_table_on_wrong_dev() -> Result { > let (_dev, drm) =3D create_drm_dev()?; > - let wrong_dev =3D faux::Registration::new(c"EvilKunit", None)?; > + let reg =3D faux::Registration::new(c"EvilKunit", None)?; > + let wrong_dev =3D reg.as_ref(); > =20 > let obj =3D Object::::new(&drm, PAGE_SIZE, Objec= tConfig::default(), ())?; > =20 > diff --git a/rust/kernel/faux.rs b/rust/kernel/faux.rs > index 36c92ae2943c..cd0724af446b 100644 > --- a/rust/kernel/faux.rs > +++ b/rust/kernel/faux.rs > @@ -9,15 +9,63 @@ > use crate::{ > bindings, > device, > - prelude::*, // > + prelude::*, > + types::Opaque, // > }; > -use core::ptr::{ > - addr_of_mut, > - null, > - null_mut, > - NonNull, // > +use core::{ > + marker::PhantomData, > + ptr::{ > + null, > + null_mut, > + NonNull, // > + }, > }; > =20 > +/// A faux device. > +/// > +/// A faux device is a virtual device backed by the faux bus, primarily = used for scenarios where a > +/// real hardware device is not available or for testing. > +/// > +/// # Invariants > +/// > +/// The underlying `struct faux_device` is valid and the embedded `struc= t device` is initialized. > +#[repr(transparent)] > +pub struct Device( > + Opaque, > + PhantomData, > +); > + > +impl Device { > + #[inline] > + fn as_raw(&self) -> *mut bindings::faux_device { > + self.0.get() > + } > + > + /// # Safety > + /// > + /// `ptr` must be a valid pointer to a `struct faux_device`. The invariant for `Device` also says: "... and the embedded `struct device` is valid". IIUC this requirement should also be mentioned here, unless we consider that a valid `struct faux_device` also implies that its embedded `struct device` is initialized, in which case that bit can be removed from the invariant section of `Device`.