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05aa6fb1c2
Add a safe Rust abstraction for the kernel's scatter-gather list facilities (`struct scatterlist` and `struct sg_table`). This commit introduces `SGTable<T>`, a wrapper that uses a generic parameter to provide compile-time guarantees about ownership and lifetime. The abstraction provides two primary states: - `SGTable<Owned<P>>`: Represents a table whose resources are fully managed by Rust. It takes ownership of a page provider `P`, allocates the underlying `struct sg_table`, maps it for DMA, and handles all cleanup automatically upon drop. The DMA mapping's lifetime is tied to the associated device using `Devres`, ensuring it is correctly unmapped before the device is unbound. - `SGTable<Borrowed>` (or just `SGTable`): A zero-cost representation of an externally managed `struct sg_table`. It is created from a raw pointer using `SGTable::from_raw()` and provides a lifetime-bound reference (`&'a SGTable`) for operations like iteration. The API exposes a safe iterator that yields `&SGEntry` references, allowing drivers to easily access the DMA address and length of each segment in the list. Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com> Tested-by: Alexandre Courbot <acourbot@nvidia.com> Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com> Reviewed-by: Lyude Paul <lyude@redhat.com> Co-developed-by: Abdiel Janulgue <abdiel.janulgue@gmail.com> Signed-off-by: Abdiel Janulgue <abdiel.janulgue@gmail.com> Link: https://lore.kernel.org/r/20250828133323.53311-4-dakr@kernel.org Signed-off-by: Danilo Krummrich <dakr@kernel.org>
24 lines
532 B
C
24 lines
532 B
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/dma-direction.h>
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dma_addr_t rust_helper_sg_dma_address(struct scatterlist *sg)
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{
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return sg_dma_address(sg);
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}
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unsigned int rust_helper_sg_dma_len(struct scatterlist *sg)
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{
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return sg_dma_len(sg);
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}
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struct scatterlist *rust_helper_sg_next(struct scatterlist *sg)
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{
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return sg_next(sg);
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}
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void rust_helper_dma_unmap_sgtable(struct device *dev, struct sg_table *sgt,
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enum dma_data_direction dir, unsigned long attrs)
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{
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return dma_unmap_sgtable(dev, sgt, dir, attrs);
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}
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