Re: [PATCH v3 1/5] rust: miscdevice: Provide accessor to pull out miscdevice::this_device

Fiona Behrens
2024-12-05T20:23:09Z

On 5 Dec 2024, at 17:25, Lee Jones wrote:

> There are situations where a pointer to a `struct device` will become
> necessary (e.g. for calling into dev_*() functions). This accessor
> allows callers to pull this out from the `struct miscdevice`.
>
> Signed-off-by: Lee Jones <lee@kernel.org>
> ---
> rust/kernel/miscdevice.rs | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs
> index 7e2a79b3ae26..55340f316006 100644
> --- a/rust/kernel/miscdevice.rs
> +++ b/rust/kernel/miscdevice.rs
> @@ -10,11 +10,13 @@
>
> use crate::{
> bindings,
> + device::Device,
> error::{to_result, Error, Result, VTABLE_DEFAULT_ERROR},
> prelude::*,
> str::CStr,
> types::{ForeignOwnable, Opaque},
> };
> +
> use core::{
> ffi::{c_int, c_long, c_uint, c_ulong},
> marker::PhantomData,
> @@ -84,6 +86,13 @@ pub fn register(opts: MiscDeviceOptions) -> impl PinInit<Self, Error> {
> pub fn as_raw(&self) -> *mut bindings::miscdevice {
> self.inner.get()
> }
> +
> + /// Returns a pointer to the current Device

I would not call this pointer but rather reference? Pointer is usually associated with *mut or *const, and this is a reference to the Device abstraction

Thanks,
- Fiona

> + pub fn device(&self) -> &Device {
> + // SAFETY: This is only accessible after a successful register() which always
> + // initialises this_device with a valid device.
> + unsafe { Device::as_ref((*self.as_raw()).this_device) }
> + }
> }
>
> #[pinned_drop]
> --
> 2.47.0.338.g60cca15819-goog