///
/// # Invariants
///
-/// The pointer stored in `Self` is non-null and valid for the lifetime of the `ARef` instance. In
-/// particular, the `ARef` instance owns an increment on the underlying object’s reference count.
+/// A `Device` instance represents a valid `struct device` created by the C portion of the kernel.
+///
+/// Instances of this type are always reference-counted, that is, a call to `get_device` ensures
+/// that the allocation remains valid at least until the matching call to `put_device`.
///
/// `bindings::device::release` is valid to be called from any thread, hence `ARef<Device>` can be
/// dropped from any thread.
// CAST: `Self` is a `repr(transparent)` wrapper around `bindings::device`.
let ptr = ptr.cast::<Self>();
- // SAFETY: By the safety requirements, ptr is valid.
+ // SAFETY: `ptr` is valid by the safety requirements of this function. By the above call to
+ // `bindings::get_device` we also own a reference to the underlying `struct device`.
unsafe { ARef::from_raw(ptr::NonNull::new_unchecked(ptr)) }
}