Re: [PATCH v1] rust: Add some DMA helpers for architectures without CONFIG_HAS_DMA

["Danilo Krummrich" <dakr@kernel.org>]

(Cc: stable@vger.kernel.org)

On Thu Dec 4, 2025 at 5:06 PM CET, FUJITA Tomonori wrote:
> Add dma_set_mask(), dma_set_coherent_mask(), dma_map_sgtable(), and
> dma_max_mapping_size() helpers to fix a build error when
> CONFIG_HAS_DMA is not enabled.
>
> Note that when CONFIG_HAS_DMA is enabled, they are included in both
> bindings_generated.rs and bindings_helpers_generated.rs. The former
> takes precedence so behavior remains unchanged in that case.
>
> This fixes the following build error on UML:
>
> error[E0425]: cannot find function `dma_set_mask` in crate `bindings`
>      --> /linux/rust/kernel/dma.rs:46:38
>       |
>    46 |         to_result(unsafe { bindings::dma_set_mask(self.as_ref().as_raw(), mask.value()) })
>       |                                      ^^^^^^^^^^^^ help: a function with a similar name exists: `xa_set_mark`
>       |
>      ::: /build/um/rust/bindings/bindings_generated.rs:24690:5
>       |
> 24690 |     pub fn xa_set_mark(arg1: *mut xarray, index: ffi::c_ulong, arg2: xa_mark_t);
>       |     ---------------------------------------------------------------------------- similarly named function `xa_set_mark` defined here
>
> error[E0425]: cannot find function `dma_set_coherent_mask` in crate `bindings`
>      --> /linux/rust/kernel/dma.rs:63:38
>       |
>    63 |         to_result(unsafe { bindings::dma_set_coherent_mask(self.as_ref().as_raw(), mask.value()) })
>       |                                      ^^^^^^^^^^^^^^^^^^^^^ help: a function with a similar name exists: `dma_coherent_ok`
>       |
>      ::: /build/um/rust/bindings/bindings_generated.rs:52745:5
>       |
> 52745 |     pub fn dma_coherent_ok(dev: *mut device, phys: phys_addr_t, size: usize) -> bool_;
>       |     ---------------------------------------------------------------------------------- similarly named function `dma_coherent_ok` defined here
>
> error[E0425]: cannot find function `dma_map_sgtable` in crate `bindings`
>     --> /linux/rust/kernel/scatterlist.rs:212:23
>      |
>  212 |               bindings::dma_map_sgtable(dev.as_raw(), sgt.as_ptr(), dir.into(), 0)
>      |                         ^^^^^^^^^^^^^^^ help: a function with a similar name exists: `dma_unmap_sgtable`
>      |
>     ::: /build/um/rust/bindings/bindings_helpers_generated.rs:1351:5
>      |
> 1351 | /     pub fn dma_unmap_sgtable(
> 1352 | |         dev: *mut device,
> 1353 | |         sgt: *mut sg_table,
> 1354 | |         dir: dma_data_direction,
> 1355 | |         attrs: ffi::c_ulong,
> 1356 | |     );
>      | |______- similarly named function `dma_unmap_sgtable` defined here
>
> error[E0425]: cannot find function `dma_max_mapping_size` in crate `bindings`
>    --> /linux/rust/kernel/scatterlist.rs:356:52
>     |
> 356 |         let max_segment = match unsafe { bindings::dma_max_mapping_size(dev.as_raw()) } {
>     |                                                    ^^^^^^^^^^^^^^^^^^^^ not found in `bindings`
>
> error: aborting due to 4 previous errors
>
> Fixes: 101d66828a4ee ("rust: dma: add DMA addressing capabilities")
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>

Applied to driver-core-linus, thanks!

    [ Use relative paths in the error splat; add 'dma' prefix. - Danilo ]