Re: [PATCH] rust: block: mq: align init_request numa_node arg with C signature

[mateusz.nowicki@posteo.net]

Hello Andreas,

how can I catch it earlier in the future? I verified patch correctness 
with compiling 'allyesconfig' but
I didn't catch rust issue.

Regards,
Mateusz

On 27.05.2026 11:18, Andreas Hindborg wrote:
> Commit b040a1a4523d ("block: switch numa_node to int in
> blk_mq_hw_ctx and init_request") changed the type of the
> `numa_node` argument of `blk_mq_ops::init_request` from
> `unsigned int` to `int`. Update the Rust callback signature to
> match, so that the function item can be coerced to the C fn
> pointer type stored in `blk_mq_ops`.
> 
> Without this change the Rust block layer fails to build:
> 
>   error[E0308]: mismatched types
>      --> rust/kernel/block/mq/operations.rs:274:28
>       |
>   274 |         init_request: Some(Self::init_request_callback),
>       |                       ---- ^^^^^^^^^^^^^^^^^^^^^^^^^^^
>       |                       expected fn pointer, found fn item
>       |
>       = note: expected fn pointer
>                 `unsafe extern "C" fn(_, _, _, i32) -> _`
>                     found fn item
>                 `unsafe extern "C" fn(_, _, _, u32) -> _ {...}`
> 
> The argument is unused on the Rust side, so this is a pure
> type-signature change with no functional impact.
> 
> Fixes: b040a1a4523d ("block: switch numa_node to int in blk_mq_hw_ctx
> and init_request")
> Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
> ---
>  rust/kernel/block/mq/operations.rs | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/rust/kernel/block/mq/operations.rs
> b/rust/kernel/block/mq/operations.rs
> index 8ad46129a52c..861903e18fbf 100644
> --- a/rust/kernel/block/mq/operations.rs
> +++ b/rust/kernel/block/mq/operations.rs
> @@ -218,7 +218,7 @@ impl<T: Operations> OperationsVTable<T> {
>          _set: *mut bindings::blk_mq_tag_set,
>          rq: *mut bindings::request,
>          _hctx_idx: crate::ffi::c_uint,
> -        _numa_node: crate::ffi::c_uint,
> +        _numa_node: crate::ffi::c_int,
>      ) -> crate::ffi::c_int {
>          from_result(|| {
>              // SAFETY: By the safety requirements of this function, 
> `rq` points
> 
> ---
> base-commit: 27236c051c01c1c1025e0e0d12a107082557e8f1
> change-id: 20260527-block-for-next-2026-05-26-2200-failure-64907085fc49
> 
> Best regards,