From: Gary Guo Date: Fri, 20 Mar 2026 19:45:38 +0000 (+0100) Subject: rust: dma: add zeroed constructor to `Coherent` X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f84ecffa3f745572164c1269f20eec2589d432c9;p=thirdparty%2Fkernel%2Flinux.git rust: dma: add zeroed constructor to `Coherent` These constructors create a coherent container of a single object instead of slice. They are named `zeroed` and `zeroed_with_attrs` to emphasis that they are created initialized zeroed. It is intended that there'll be new constructors that take `PinInit` instead of zeroing. Signed-off-by: Gary Guo Reviewed-by: Alice Ryhl Reviewed-by: Alexandre Courbot Link: https://patch.msgid.link/20260320194626.36263-4-dakr@kernel.org [ Use kernel import style. - Danilo ] Signed-off-by: Danilo Krummrich --- diff --git a/rust/kernel/dma.rs b/rust/kernel/dma.rs index ff3e147f1a23b..59477c865dd39 100644 --- a/rust/kernel/dma.rs +++ b/rust/kernel/dma.rs @@ -47,7 +47,7 @@ pub trait Device: AsRef> { /// # Safety /// /// This method must not be called concurrently with any DMA allocation or mapping primitives, - /// such as [`CoherentAllocation::alloc_attrs`]. + /// such as [`Coherent::zeroed`]. unsafe fn dma_set_mask(&self, mask: DmaMask) -> Result { // SAFETY: // - By the type invariant of `device::Device`, `self.as_ref().as_raw()` is valid. @@ -64,7 +64,7 @@ pub trait Device: AsRef> { /// # Safety /// /// This method must not be called concurrently with any DMA allocation or mapping primitives, - /// such as [`CoherentAllocation::alloc_attrs`]. + /// such as [`Coherent::zeroed`]. unsafe fn dma_set_coherent_mask(&self, mask: DmaMask) -> Result { // SAFETY: // - By the type invariant of `device::Device`, `self.as_ref().as_raw()` is valid. @@ -83,7 +83,7 @@ pub trait Device: AsRef> { /// # Safety /// /// This method must not be called concurrently with any DMA allocation or mapping primitives, - /// such as [`CoherentAllocation::alloc_attrs`]. + /// such as [`Coherent::zeroed`]. unsafe fn dma_set_mask_and_coherent(&self, mask: DmaMask) -> Result { // SAFETY: // - By the type invariant of `device::Device`, `self.as_ref().as_raw()` is valid. @@ -102,7 +102,7 @@ pub trait Device: AsRef> { /// # Safety /// /// This method must not be called concurrently with any DMA allocation or mapping primitives, - /// such as [`CoherentAllocation::alloc_attrs`]. + /// such as [`Coherent::zeroed`]. unsafe fn dma_set_max_seg_size(&self, size: u32) { // SAFETY: // - By the type invariant of `device::Device`, `self.as_ref().as_raw()` is valid. @@ -202,12 +202,12 @@ impl DmaMask { /// /// ``` /// # use kernel::device::{Bound, Device}; -/// use kernel::dma::{attrs::*, CoherentAllocation}; +/// use kernel::dma::{attrs::*, Coherent}; /// /// # fn test(dev: &Device) -> Result { /// let attribs = DMA_ATTR_FORCE_CONTIGUOUS | DMA_ATTR_NO_WARN; -/// let c: CoherentAllocation = -/// CoherentAllocation::alloc_attrs(dev, 4, GFP_KERNEL, attribs)?; +/// let c: Coherent<[u64]> = +/// Coherent::zeroed_slice_with_attrs(dev, 4, GFP_KERNEL, attribs)?; /// # Ok::<(), Error>(()) } /// ``` #[derive(Clone, Copy, PartialEq)] @@ -492,7 +492,6 @@ impl Coherent { impl Coherent { /// Allocates a region of `T` of coherent memory. - #[expect(unused)] fn alloc_with_attrs( dev: &device::Device, gfp_flags: kernel::alloc::Flags, @@ -529,6 +528,41 @@ impl Coherent { }) } + /// Allocates a region of type `T` of coherent memory. + /// + /// # Examples + /// + /// ``` + /// # use kernel::device::{ + /// # Bound, + /// # Device, + /// # }; + /// use kernel::dma::{ + /// attrs::*, + /// Coherent, + /// }; + /// + /// # fn test(dev: &Device) -> Result { + /// let c: Coherent<[u64; 4]> = + /// Coherent::zeroed_with_attrs(dev, GFP_KERNEL, DMA_ATTR_NO_WARN)?; + /// # Ok::<(), Error>(()) } + /// ``` + #[inline] + pub fn zeroed_with_attrs( + dev: &device::Device, + gfp_flags: kernel::alloc::Flags, + dma_attrs: Attrs, + ) -> Result { + Self::alloc_with_attrs(dev, gfp_flags | __GFP_ZERO, dma_attrs) + } + + /// Performs the same functionality as [`Coherent::zeroed_with_attrs`], except the + /// `dma_attrs` is 0 by default. + #[inline] + pub fn zeroed(dev: &device::Device, gfp_flags: kernel::alloc::Flags) -> Result { + Self::zeroed_with_attrs(dev, gfp_flags, Attrs(0)) + } + /// Allocates a region of `[T; len]` of coherent memory. fn alloc_slice_with_attrs( dev: &device::Device, @@ -572,6 +606,49 @@ impl Coherent { dma_attrs, }) } + + /// Allocates a zeroed region of type `T` of coherent memory. + /// + /// Unlike `Coherent::<[T; N]>::zeroed_with_attrs`, `Coherent::::zeroed_slices` support + /// a runtime length. + /// + /// # Examples + /// + /// ``` + /// # use kernel::device::{ + /// # Bound, + /// # Device, + /// # }; + /// use kernel::dma::{ + /// attrs::*, + /// Coherent, + /// }; + /// + /// # fn test(dev: &Device) -> Result { + /// let c: Coherent<[u64]> = + /// Coherent::zeroed_slice_with_attrs(dev, 4, GFP_KERNEL, DMA_ATTR_NO_WARN)?; + /// # Ok::<(), Error>(()) } + /// ``` + #[inline] + pub fn zeroed_slice_with_attrs( + dev: &device::Device, + len: usize, + gfp_flags: kernel::alloc::Flags, + dma_attrs: Attrs, + ) -> Result> { + Coherent::alloc_slice_with_attrs(dev, len, gfp_flags | __GFP_ZERO, dma_attrs) + } + + /// Performs the same functionality as [`Coherent::zeroed_slice_with_attrs`], except the + /// `dma_attrs` is 0 by default. + #[inline] + pub fn zeroed_slice( + dev: &device::Device, + len: usize, + gfp_flags: kernel::alloc::Flags, + ) -> Result> { + Self::zeroed_slice_with_attrs(dev, len, gfp_flags, Attrs(0)) + } } impl Coherent<[T]> { diff --git a/samples/rust/rust_dma.rs b/samples/rust/rust_dma.rs index ce39b55450978..129bb4b39c044 100644 --- a/samples/rust/rust_dma.rs +++ b/samples/rust/rust_dma.rs @@ -6,7 +6,12 @@ use kernel::{ device::Core, - dma::{CoherentAllocation, DataDirection, Device, DmaMask}, + dma::{ + Coherent, + DataDirection, + Device, + DmaMask, // + }, page, pci, prelude::*, scatterlist::{Owned, SGTable}, @@ -16,7 +21,7 @@ use kernel::{ #[pin_data(PinnedDrop)] struct DmaSampleDriver { pdev: ARef, - ca: CoherentAllocation, + ca: Coherent<[MyStruct]>, #[pin] sgt: SGTable>>, } @@ -64,8 +69,8 @@ impl pci::Driver for DmaSampleDriver { // SAFETY: There are no concurrent calls to DMA allocation and mapping primitives. unsafe { pdev.dma_set_mask_and_coherent(mask)? }; - let ca: CoherentAllocation = - CoherentAllocation::alloc_coherent(pdev.as_ref(), TEST_VALUES.len(), GFP_KERNEL)?; + let ca: Coherent<[MyStruct]> = + Coherent::zeroed_slice(pdev.as_ref(), TEST_VALUES.len(), GFP_KERNEL)?; for (i, value) in TEST_VALUES.into_iter().enumerate() { kernel::dma_write!(ca, [i]?, MyStruct::new(value.0, value.1));