Re: [PATCH v18 1/4] rust: drm: gem: shmem: Add DmaResvGuard helper

[Alexandre Courbot]

On Fri Jun 5, 2026 at 4:24 AM JST, Lyude Paul wrote:
> Just a temporary holdover to make locking/unlocking the dma_resv lock much
> easier.
>
> Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
> Co-authored-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
> Signed-off-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
>
> ---
> V17:
> * Fix format of commit message title
>
>  rust/kernel/drm/gem/shmem.rs | 31 ++++++++++++++++++++++++++++++-
>  1 file changed, 30 insertions(+), 1 deletion(-)
>
> diff --git a/rust/kernel/drm/gem/shmem.rs b/rust/kernel/drm/gem/shmem.rs
> index 084b798ce795b..650c34dd8b7a4 100644
> --- a/rust/kernel/drm/gem/shmem.rs
> +++ b/rust/kernel/drm/gem/shmem.rs
> @@ -30,7 +30,10 @@
>          Deref,
>          DerefMut, //
>      },
> -    ptr::NonNull, //
> +    ptr::{
> +        self,
> +        NonNull, //
> +    },
>  };
>  use gem::{
>      BaseObjectPrivate,
> @@ -244,3 +247,29 @@ impl<T: DriverObject, C: DeviceContext> driver::AllocImpl for Object<T, C> {
>          dumb_map_offset: None,
>      };
>  }
> +
> +/// Private helper-type for holding the `dma_resv` object for a GEM shmem object.
> +///
> +/// When this is dropped, the `dma_resv` lock is dropped as well.
> +///
> +// TODO: This should be replace with a WwMutex equivalent once we have such bindings in the kernel.
> +struct DmaResvGuard<'a, T: DriverObject, C: DeviceContext = Registered>(&'a Object<T, C>);

Should this be made `NotThreadSafe` as suggested by Alice? [1]

[1] https://lore.kernel.org/all/ahbglxo5yePyjE81@xxxxxxxxxx/