In order to implement the gem export callback, we need a type to represent struct dma_buf. So - this commit introduces a set of stub bindings for dma_buf. These bindings provide a ref-counted DmaBuf object, but don't currently implement any functionality for using the DmaBuf.
Signed-off-by: Lyude Paul lyude@redhat.com Reviewed-by: Daniel Almeida daniel.almeida@collabora.com
--- V3: * Rename as_ref() to from_raw() V4: * Add missing period to rustdoc at top of file
rust/kernel/dma_buf.rs | 40 ++++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + 2 files changed, 41 insertions(+) create mode 100644 rust/kernel/dma_buf.rs
diff --git a/rust/kernel/dma_buf.rs b/rust/kernel/dma_buf.rs new file mode 100644 index 0000000000000..50be3e4dd4098 --- /dev/null +++ b/rust/kernel/dma_buf.rs @@ -0,0 +1,40 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! DMA buffer API. +//! +//! C header: [`include/linux/dma-buf.h`](srctree/include/linux/dma-buf.h) + +use bindings; +use kernel::types::*; + +/// A DMA buffer object. +/// +/// # Invariants +/// +/// The data layout of this type is equivalent to that of `struct dma_buf`. +#[repr(transparent)] +pub struct DmaBuf(Opaquebindings::dma_buf); + +// SAFETY: `struct dma_buf` is thread-safe +unsafe impl Send for DmaBuf {} +// SAFETY: `struct dma_buf` is thread-safe +unsafe impl Sync for DmaBuf {} + +#[expect(unused)] +impl DmaBuf { + /// Convert from a `*mut bindings::dma_buf` to a [`DmaBuf`]. + /// + /// # Safety + /// + /// The caller guarantees that `self_ptr` points to a valid initialized `struct dma_buf` for the + /// duration of the lifetime of `'a`, and promises to not violate rust's data aliasing rules + /// using the reference provided by this function. + pub(crate) unsafe fn from_raw<'a>(self_ptr: *mut bindings::dma_buf) -> &'a Self { + // SAFETY: Our data layout is equivalent to `dma_buf` . + unsafe { &*self_ptr.cast() } + } + + pub(crate) fn as_raw(&self) -> *mut bindings::dma_buf { + self.0.get() + } +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index fcffc3988a903..59242d83efe21 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -81,6 +81,7 @@ pub mod device_id; pub mod devres; pub mod dma; +pub mod dma_buf; pub mod driver; #[cfg(CONFIG_DRM = "y")] pub mod drm;