Re: [PATCH] rust: drm: gem: add missing handle_free to the object vtables

["Gary Guo" <gary@garyguo.net>]

On Wed Sep 9, 2026 at 10:47 AM BST, Mike Lothian wrote:
> Both OBJECT_FUNCS and the shmem VTABLE initialise every member of
> drm_gem_object_funcs explicitly, so adding a field to the C struct
> breaks the Rust build:
>
>   error[E0063]: missing field `handle_free` in initializer of
>   `drm_gem_object_funcs`
>
> The callback is optional and the Rust abstraction has no equivalent
> DriverObject method, so leave it unset.
>
> The shmem copy is only built with CONFIG_RUST_DRM_GEM_SHMEM_HELPER,
> which DRM_TYR selects.
>
> Fixes: b67d2d039f64 ("drm/gem: Add callback for when handle count goes to 0")
> Signed-off-by: Mike Lothian <mike@fireburn.co.uk>
> Assisted-by: Claude:Opus-5 [Claude Code]

There's
https://lore.kernel.org/dri-devel/20260908175427.47207-1-klarasmodin@gmail.com/.

Best,
Gary

> ---
>
> b67d2d039f64 is only in agd5f/drm-next, so this can be squashed into it
> instead if you would rather keep that branch bisectable.
>
> The shmem hunk is by inspection - CONFIG_RUST_DRM_GEM_SHMEM_HELPER is
> not set in my config, so only the mod.rs copy is compile-tested.
>
>  rust/kernel/drm/gem/mod.rs   | 1 +
>  rust/kernel/drm/gem/shmem.rs | 1 +
>  2 files changed, 2 insertions(+)
>
> diff --git a/rust/kernel/drm/gem/mod.rs b/rust/kernel/drm/gem/mod.rs
> index 80d8f524f9d5..ae61ca7e1246 100644
> --- a/rust/kernel/drm/gem/mod.rs
> +++ b/rust/kernel/drm/gem/mod.rs
> @@ -278,6 +278,7 @@ impl<T: DriverObject, Ctx: DeviceContext> Object<T, Ctx> {
>          vm_ops: core::ptr::null_mut(),
>          evict: None,
>          rss: None,
> +        handle_free: None,
>      };
>  
>      /// Returns the `Device` that owns this GEM object.
> diff --git a/rust/kernel/drm/gem/shmem.rs b/rust/kernel/drm/gem/shmem.rs
> index a687d46d170d..d08a03cb7a13 100644
> --- a/rust/kernel/drm/gem/shmem.rs
> +++ b/rust/kernel/drm/gem/shmem.rs
> @@ -145,6 +145,7 @@ impl<T: DriverObject> Object<T> {
>          // SAFETY: `drm_gem_shmem_vm_ops` is a valid, static const on the C side.
>          vm_ops: unsafe { &raw const bindings::drm_gem_shmem_vm_ops },
>          evict: None,
> +        handle_free: None,
>      };
>  
>      /// Return a raw pointer to the embedded drm_gem_shmem_object.