Re: [PATCH v1 1/3] rust: sync: Add smp_store_release/smp_load_acquire helpers

[Boqun Feng <boqun.feng@gmail.com>]

Hi Tomo,

Thanks for taking a look at this.

On Sat, Nov 15, 2025 at 02:03:03PM +0900, FUJITA Tomonori wrote:
> Add smp_store_release/smp_load_acquire helpers to support
> store_release/load_acquire for i8/i16.
> 
> Both are implemented as a C macro and type information is necessary so
> the size argument is necessary unlike the C version.
> 
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
> ---
>  rust/helpers/barrier.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/rust/helpers/barrier.c b/rust/helpers/barrier.c

Could you just define helpers:

atomic_{i8,i16}_store{,_release}(), atomic_{i8,i16}_load{,_acquire}()

in a separate helper file? (e.g. rust/helpers/atomic_ext.c).

In this way, you could just use C to implement these and that'll make
the interface Rust/C more clear.

Eventually I will the macro declare_and_impl_atomic_methods!() support
customized list of types, but right now a dedicated macro to generate
all impls for AtomicBasicOps of i8/i16 is fine.

Regards,
Boqun

> index cdf28ce8e511..b66ef792c7be 100644
> --- a/rust/helpers/barrier.c
> +++ b/rust/helpers/barrier.c
> @@ -16,3 +16,27 @@ void rust_helper_smp_rmb(void)
>  {
>  	smp_rmb();
>  }
> +
> +void rust_helper_smp_store_release(void *ptr, u64 val, size_t size)
> +{
> +	switch (size) {
> +	case 1:
> +		smp_store_release((u8 *)ptr, (u8)val);
> +		break;
> +	case 2:
> +		smp_store_release((u16 *)ptr, (u16)val);
> +		break;
> +	}
> +}
> +
> +void rust_helper_smp_load_acquire(void *ptr, void *val, size_t size)
> +{
> +	switch (size) {
> +	case 1:
> +		*(u8 *)val = smp_load_acquire((u8 *)ptr);
> +		break;
> +	case 2:
> +		*(u16 *)val = smp_load_acquire((u16 *)ptr);
> +		break;
> +	}
> +}
> -- 
> 2.43.0
>