Re: [PATCH] cpufreq: rust: Use C FFI types in bios_limit_callback

["Benno Lossin" <lossin@kernel.org>]

On Thu Jun 12, 2025 at 8:09 AM CEST, Abhinav Ananthu wrote:
> Update the bios_limit_callback function to use C FFI-compatible types
> (kernel::ffi::c_int and kernel::ffi::c_uint) for its parameters and return
> value. This ensures ABI compatibility with the corresponding C callback
> signature.
>
> Reported-by: Miguel Ojeda <ojeda@kernel.org>
> Closes: https://lore.kernel.org/rust-for-linux/CANiq72=WpuGELzLbH-fxdOeJy9fiDFwatz6ynERDh=HP2z2MBw@mail.gmail.com/.
> Signed-off-by: Abhinav Ananthu <abhinav.ogl@gmail.com>
> ---
>  rust/kernel/cpufreq.rs | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
> index b0a9c6182aec..7ef2f64d8f34 100644
> --- a/rust/kernel/cpufreq.rs
> +++ b/rust/kernel/cpufreq.rs
> @@ -1277,7 +1277,7 @@ extern "C" fn update_limits_callback(ptr: *mut bindings::cpufreq_policy) {
>      /// Driver's `bios_limit` callback.
>      ///
>      /// SAFETY: Called from C. Inputs must be valid pointers.
> -    extern "C" fn bios_limit_callback(cpu: i32, limit: *mut u32) -> kernel::ffi::c_int {
> +    extern "C" fn bios_limit_callback(cpu: kernel::ffi::c_int, limit: *mut kernel::ffi::c_uint) -> kernel::ffi::c_int {

This file imports the kernel's prelude, so you should be able to just
use `c_int` and `c_uint` instead of their qualified names.

---
Cheers,
Benno

>          from_result(|| {
>              let mut policy = PolicyCpu::from_cpu(cpu as u32)?;
>