Re: [PATCH v3 02/14] rust: drm: gem: Add DriverFile type alias

[Daniel Almeida <daniel.almeida@collabora.com>]

> On 29 Aug 2025, at 19:35, Lyude Paul <lyude@redhat.com> wrote:
> 
> Just to reduce the clutter with the File<…> types in gem.rs.
> 
> Signed-off-by: Lyude Paul <lyude@redhat.com>
> 
> ---
> V3:
> * Rename ObjectFile to DriverFile
> 
> Signed-off-by: Lyude Paul <lyude@redhat.com>
> ---
> rust/kernel/drm/gem/mod.rs | 23 ++++++++++++-----------
> 1 file changed, 12 insertions(+), 11 deletions(-)
> 
> diff --git a/rust/kernel/drm/gem/mod.rs b/rust/kernel/drm/gem/mod.rs
> index 31c5799d995c5..80940ed11368d 100644
> --- a/rust/kernel/drm/gem/mod.rs
> +++ b/rust/kernel/drm/gem/mod.rs
> @@ -14,6 +14,13 @@
> };
> use core::{mem, ops::Deref, ptr::NonNull};
> 
> +/// A type alias for retrieving a [`Driver`]s [`DriverFile`] implementation from its
> +/// [`DriverObject`] implementation.
> +///
> +/// [`Driver`]: drm::Driver
> +/// [`DriverFile`]: drm::file::DriverFile
> +pub type DriverFile<T> = drm::File<<<T as DriverObject>::Driver as drm::Driver>::File>;
> +
> /// GEM object functions, which must be implemented by drivers.
> pub trait DriverObject: Sync + Send + Sized {
>     /// Parent `Driver` for this object.
> @@ -23,19 +30,12 @@ pub trait DriverObject: Sync + Send + Sized {
>     fn new(dev: &drm::Device<Self::Driver>, size: usize) -> impl PinInit<Self, Error>;
> 
>     /// Open a new handle to an existing object, associated with a File.
> -    fn open(
> -        _obj: &<Self::Driver as drm::Driver>::Object,
> -        _file: &drm::File<<Self::Driver as drm::Driver>::File>,
> -    ) -> Result {
> +    fn open(_obj: &<Self::Driver as drm::Driver>::Object, _file: &DriverFile<Self>) -> Result {
>         Ok(())
>     }
> 
>     /// Close a handle to an existing object, associated with a File.
> -    fn close(
> -        _obj: &<Self::Driver as drm::Driver>::Object,
> -        _file: &drm::File<<Self::Driver as drm::Driver>::File>,
> -    ) {
> -    }
> +    fn close(_obj: &<Self::Driver as drm::Driver>::Object, _file: &DriverFile<Self>) {}
> }
> 
> /// Trait that represents a GEM object subtype
> @@ -79,7 +79,8 @@ extern "C" fn open_callback<T: DriverObject>(
>     raw_file: *mut bindings::drm_file,
> ) -> core::ffi::c_int {
>     // SAFETY: `open_callback` is only ever called with a valid pointer to a `struct drm_file`.
> -    let file = unsafe { drm::File::<<T::Driver as drm::Driver>::File>::from_raw(raw_file) };
> +    let file = unsafe { DriverFile::<T>::from_raw(raw_file) };
> +
>     // SAFETY: `open_callback` is specified in the AllocOps structure for `DriverObject<T>`,
>     // ensuring that `raw_obj` is contained within a `DriverObject<T>`
>     let obj = unsafe { <<T::Driver as drm::Driver>::Object as IntoGEMObject>::from_raw(raw_obj) };
> @@ -95,7 +96,7 @@ extern "C" fn close_callback<T: DriverObject>(
>     raw_file: *mut bindings::drm_file,
> ) {
>     // SAFETY: `open_callback` is only ever called with a valid pointer to a `struct drm_file`.
> -    let file = unsafe { drm::File::<<T::Driver as drm::Driver>::File>::from_raw(raw_file) };
> +    let file = unsafe { DriverFile::<T>::from_raw(raw_file) };
> 
>     // SAFETY: `close_callback` is specified in the AllocOps structure for `Object<T>`, ensuring
>     // that `raw_obj` is indeed contained within a `Object<T>`.
> -- 
> 2.50.0
> 
> 

Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>