Re: [PATCH v4 13/16] rust: drm: add AsRef<ParentDevice<Bound>> for Device<Registered>

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Missing `#[inline]` annotation on the small forwarding function `as_ref` in an abstraction crate.
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commit 61d54b007aa9572681d918fcd5c48802182d8282
Author: Danilo Krummrich <dakr@kernel.org>

rust: drm: add AsRef<ParentDevice<Bound>> for Device<Registered>

This commit implements AsRef<T::ParentDevice<Bound>> for Device<T, Registered>.
It provides safe access to the bound parent bus device for registered DRM
devices.

> diff --git a/rust/kernel/drm/device.rs b/rust/kernel/drm/device.rs
> index 45bacd7b227f0..8f63276c9b62f 100644
> --- a/rust/kernel/drm/device.rs
> +++ b/rust/kernel/drm/device.rs
> @@ -462,6 +462,19 @@ fn as_ref(&self) -> &T::ParentDevice<device::Normal> {
>      }
>  }
>  
> +impl<T: drm::Driver> AsRef<T::ParentDevice<device::Bound>> for Device<T, Registered> {
> +    fn as_ref(&self) -> &T::ParentDevice<device::Bound> {

[Severity: Low]
This isn't a bug, but should this small forwarding function in an abstraction
crate have an #[inline] annotation?

The Rust subsystem coding guidelines mention that functions in abstractions
that are small or simply forwarding calls should be annotated with #[inline].
Since as_ref() performs purely type-level conversions and pointer coercions,
adding the annotation might help the compiler reliably optimize these across
crate boundaries.

> +        let dev = (**self).as_ref().as_ref();
> +
> +        // SAFETY: A `Device<T, Registered>` guarantees that the parent device is bound.
> +        let dev = unsafe { dev.as_bound() };
> +
> +        // SAFETY: By the type invariant of `Device`, the parent device is embedded in
> +        // `T::ParentDevice`.
> +        unsafe { device::AsBusDevice::from_device(dev) }
> +    }
> +}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260620184924.2247517-1-dakr@kernel.org?part=13