This introduces an optional export() callback for GEM objects, which is used to implement the drm_gem_object_funcs->export function.
Signed-off-by: Lyude Paul lyude@redhat.com --- drivers/gpu/drm/nova/gem.rs | 1 + rust/kernel/drm/gem/mod.rs | 72 +++++++++++++++++++++++++++++++++++- rust/kernel/drm/gem/shmem.rs | 6 ++- 3 files changed, 76 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/nova/gem.rs b/drivers/gpu/drm/nova/gem.rs index 015cb56061a56..bbce6b0f4e6a4 100644 --- a/drivers/gpu/drm/nova/gem.rs +++ b/drivers/gpu/drm/nova/gem.rs @@ -16,6 +16,7 @@ #[pin_data] pub(crate) struct NovaObject {}
+#[vtable] impl gem::DriverObject for NovaObject { type Driver = NovaDriver; type Object = gem::Object<Self>; diff --git a/rust/kernel/drm/gem/mod.rs b/rust/kernel/drm/gem/mod.rs index f9f9727f14e4a..1ac25fc6d527b 100644 --- a/rust/kernel/drm/gem/mod.rs +++ b/rust/kernel/drm/gem/mod.rs @@ -8,7 +8,7 @@
use crate::{ alloc::flags::*, - bindings, + bindings, dma_buf, drm::driver::{AllocImpl, AllocOps}, drm::{self, private::Sealed}, error::{to_result, Result}, @@ -45,6 +45,7 @@ fn as_ref(&self) -> &kernel::drm::gem::OpaqueObject<D> { pub(crate) use impl_as_opaque;
/// GEM object functions, which must be implemented by drivers. +#[vtable] pub trait DriverObject: Sync + Send + Sized { /// Parent `Driver` for this object. type Driver: drm::Driver; @@ -69,6 +70,11 @@ fn open(_obj: &Self::Object, _file: &DriverFile<Self>) -> Result {
/// Close a handle to an existing object, associated with a File. fn close(_obj: &Self::Object, _file: &DriverFile<Self>) {} + + /// Optional handle for exporting a gem object. + fn export(_obj: &Self::Object, _flags: u32) -> Result<DmaBufSelf::Object> { + unimplemented!() + } }
/// Trait that represents a GEM object subtype @@ -138,6 +144,21 @@ extern "C" fn close_callback<T: DriverObject>( T::close(obj, file); }
+extern "C" fn export_callback<T: DriverObject>( + raw_obj: *mut bindings::drm_gem_object, + flags: i32, +) -> *mut bindings::dma_buf { + // SAFETY: `export_callback` is specified in the AllocOps structure for `Object<T>`, ensuring + // that `raw_obj` is contained within a `Object<T>`. + let obj = unsafe { T::Object::from_raw(raw_obj) }; + + match T::export(obj, flags as u32) { + // DRM takes a hold of the reference + Ok(buf) => buf.into_raw(), + Err(e) => e.to_ptr(), + } +} + impl<T: DriverObject> IntoGEMObject for Object<T> { fn as_raw(&self) -> *mut bindings::drm_gem_object { self.obj.get() @@ -248,7 +269,11 @@ impl<T: DriverObject> Object<T> { open: Some(open_callback::<T>), close: Some(close_callback::<T>), print_info: None, - export: None, + export: if T::HAS_EXPORT { + Some(export_callback::<T>) + } else { + None + }, pin: None, unpin: None, get_sg_table: None, @@ -375,6 +400,49 @@ fn as_raw(&self) -> *mut bindings::drm_gem_object {
impl<D: drm::Driver> Sealed for OpaqueObject<D> {}
+/// A [`dma_buf::DmaBuf`] which has been exported from a GEM object. +/// +/// The [`dma_buf::DmaBuf`] will be released when this type is dropped. +/// +/// # Invariants +/// +/// - `self.0` points to a valid initialized [`dma_buf::DmaBuf`] for the lifetime of this object. +/// - The GEM object from which this [`dma_buf::DmaBuf`] was exported from is guaranteed to be of +/// type `T`. +pub struct DmaBuf<T: IntoGEMObject>(NonNull<dma_buf::DmaBuf>, PhantomData<T>); + +impl<T: IntoGEMObject> Deref for DmaBuf<T> { + type Target = dma_buf::DmaBuf; + + #[inline] + fn deref(&self) -> &Self::Target { + // SAFETY: This pointer is guaranteed to be valid by our type invariants. + unsafe { self.0.as_ref() } + } +} + +impl<T: IntoGEMObject> Drop for DmaBuf<T> { + #[inline] + fn drop(&mut self) { + // SAFETY: + // - `dma_buf::DmaBuf` is guaranteed to have an identical layout to `struct dma_buf` + // by its type invariants. + // - We hold the last reference to this `DmaBuf`, making it safe to destroy. + unsafe { bindings::drm_gem_dmabuf_release(self.0.cast().as_ptr()) } + } +} + +impl<T: IntoGEMObject> DmaBuf<T> { + /// Leak the reference for this [`DmaBuf`] and return a raw pointer to it. + #[inline] + pub(crate) fn into_raw(self) -> *mut bindings::dma_buf { + let dma_ptr = self.as_raw(); + + core::mem::forget(self); + dma_ptr + } +} + pub(super) const fn create_fops() -> bindings::file_operations { // SAFETY: As by the type invariant, it is safe to initialize `bindings::file_operations` // zeroed. diff --git a/rust/kernel/drm/gem/shmem.rs b/rust/kernel/drm/gem/shmem.rs index 1437cda27a22c..b3a70e6001842 100644 --- a/rust/kernel/drm/gem/shmem.rs +++ b/rust/kernel/drm/gem/shmem.rs @@ -66,7 +66,11 @@ impl<T: DriverObject> Object<T> { open: Some(super::open_callback::<T>), close: Some(super::close_callback::<T>), print_info: Some(bindings::drm_gem_shmem_object_print_info), - export: None, + export: if T::HAS_EXPORT { + Some(super::export_callback::<T>) + } else { + None + }, pin: Some(bindings::drm_gem_shmem_object_pin), unpin: Some(bindings::drm_gem_shmem_object_unpin), get_sg_table: Some(bindings::drm_gem_shmem_object_get_sg_table),