Just a temporary holdover to make locking/unlocking the dma_resv lock much easier.
Signed-off-by: Lyude Paul lyude@redhat.com Co-authored-by: Alexandre Courbot acourbot@nvidia.com --- 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 116ed0a13eac2..1b24cb1129a8b 100644 --- a/rust/kernel/drm/gem/shmem.rs +++ b/rust/kernel/drm/gem/shmem.rs @@ -27,7 +27,10 @@ Deref, DerefMut, // }, - ptr::NonNull, + ptr::{ + self, + NonNull, // + }, }; use gem::{ BaseObjectPrivate, @@ -233,3 +236,29 @@ impl<T: DriverObject> driver::AllocImpl for Object<T> { 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>(&'a Object<T>); + +impl<'a, T: DriverObject> DmaResvGuard<'a, T> { + #[inline(always)] + #[expect(unused)] + fn new(obj: &'a Object<T>) -> Self { + // SAFETY: This lock is initialized throughout the lifetime of `object`. + unsafe { bindings::dma_resv_lock(obj.raw_dma_resv(), ptr::null_mut()) }; + + Self(obj) + } +} + +impl<'a, T: DriverObject> Drop for DmaResvGuard<'a, T> { + #[inline(always)] + fn drop(&mut self) { + // SAFETY: We are releasing the lock grabbed during the creation of this object. + unsafe { bindings::dma_resv_unlock(self.0.raw_dma_resv()) }; + } +}