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 at redhat.com>
---
drivers/gpu/drm/nova/gem.rs | 1 +
rust/kernel/drm/gem/mod.rs | 73 +++++++++++++++++++++++++++++++++++-
rust/kernel/drm/gem/shmem.rs | 6 ++-
3 files changed, 77 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/nova/gem.rs b/drivers/gpu/drm/nova/gem.rs
index f2f23320110dd..6cc7a65a50fae 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::BaseDriverObject 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 6d87e75690d2f..ef697f323e52c 100644
--- a/rust/kernel/drm/gem/mod.rs
+++ b/rust/kernel/drm/gem/mod.rs
@@ -10,7 +10,8 @@
alloc::flags::*,
bindings, drm::{self, private::Sealed},
drm::driver::{AllocImpl, AllocOps},
- error::{to_result, Result},
+ dma_buf,
+ error::{to_result, from_err_ptr, Result},
prelude::*,
types::{ARef, AlwaysRefCounted, Opaque},
};
@@ -44,6 +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 BaseDriverObject: Sync + Send + Sized {
/// Parent `Driver` for this object.
type Driver: drm::Driver;
@@ -68,6 +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<DmaBuf<Self::Object>> {
+ unimplemented!()
+ }
}
/// Trait that represents a GEM object subtype
@@ -137,6 +144,21 @@ extern "C" fn close_callback<T:
BaseDriverObject>(
T::close(obj, file);
}
+extern "C" fn export_callback<T: BaseDriverObject>(
+ 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::as_ref(raw_obj) };
+
+ match T::export(obj, flags as _) {
+ // DRM takes a hold of the reference
+ Ok(buf) => buf.into_raw(),
+ Err(e) => e.to_ptr(),
+ }
+}
+
impl<T: BaseDriverObject> IntoGEMObject for Object<T> {
fn as_raw(&self) -> *mut bindings::drm_gem_object {
self.obj.get()
@@ -247,7 +269,11 @@ impl<T: BaseDriverObject> 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,
@@ -376,6 +402,49 @@ 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 bff038df93334..799f15c38cc36 100644
--- a/rust/kernel/drm/gem/shmem.rs
+++ b/rust/kernel/drm/gem/shmem.rs
@@ -77,7 +77,11 @@ impl<T: BaseDriverObject> 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),
--
2.49.0