Re: [PATCH v2] rust: helpers: Add dma_alloc_attrs() and dma_free_attrs()

[FUJITA Tomonori]

On Fri, 11 Apr 2025 11:51:03 +0200
Danilo Krummrich <dakr@xxxxxxxxxx> wrote:

> On Fri, Apr 11, 2025 at 08:43:32AM +0900, FUJITA Tomonori wrote:
>> Add dma_alloc_attrs() and dma_free_attrs() helpers to fix a build
>> error when CONFIG_HAS_DMA is not enabled.
>> 
>> Note that when CONFIG_HAS_DMA is enabled, dma_alloc_attrs() and
>> dma_free_attrs() 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_alloc_attrs` in crate `bindings`
>>      --> rust/kernel/dma.rs:171:23
>>       |
>> 171   |               bindings::dma_alloc_attrs(
>>       |                         ^^^^^^^^^^^^^^^ help: a function with a similar name exists: `dma_alloc_pages`
>>       |
>>      ::: /home/fujita/build/um/rust/bindings/bindings_generated.rs:44568:5
>>       |
>> 44568 | /     pub fn dma_alloc_pages(
>> 44569 | |         dev: *mut device,
>> 44570 | |         size: usize,
>> 44571 | |         dma_handle: *mut dma_addr_t,
>> 44572 | |         dir: dma_data_direction,
>> 44573 | |         gfp: gfp_t,
>> 44574 | |     ) -> *mut page;
>>       | |___________________- similarly named function `dma_alloc_pages` defined here
>> 
>> error[E0425]: cannot find function `dma_free_attrs` in crate `bindings`
>>      --> rust/kernel/dma.rs:293:23
>>       |
>> 293   |               bindings::dma_free_attrs(
>>       |                         ^^^^^^^^^^^^^^ help: a function with a similar name exists: `dma_free_pages`
>>       |
>>      ::: /home/fujita/build/um/rust/bindings/bindings_generated.rs:44577:5
>>       |
>> 44577 | /     pub fn dma_free_pages(
>> 44578 | |         dev: *mut device,
>> 44579 | |         size: usize,
>> 44580 | |         page: *mut page,
>> 44581 | |         dma_handle: dma_addr_t,
>> 44582 | |         dir: dma_data_direction,
>> 44583 | |     );
>>       | |______- similarly named function `dma_free_pages` defined here
>> 
>> Fixes: ad2907b4e308 ("rust: add dma coherent allocator abstraction")
>> Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxx>
> 
> Please add the new file to the corresponding MAINTAINERS entry. Whith that,
> 
> 	Acked-by: Danilo Krummrich <dakr@xxxxxxxxxx>

I'll include the following changes in the next version.

diff --git a/MAINTAINERS b/MAINTAINERS
index 96b827049501..bec614ef35d9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7020,6 +7020,7 @@ L:	rust-for-linux@xxxxxxxxxxxxxxx
 S:	Supported
 W:	https://rust-for-linux.com
 T:	git https://github.com/Rust-for-Linux/linux.git alloc-next
+F:	rust/helpers/dma.c
 F:	rust/kernel/dma.rs
 F:	samples/rust/rust_dma.rs