Re: [PATCH 4/5] rust: sync: atomic: Add Atomic<*mut T> support

[Benno Lossin]

On Sun Jan 18, 2026 at 4:05 PM CET, Boqun Feng wrote:
> On Sun, Jan 18, 2026 at 10:57:37PM +0800, Boqun Feng wrote:
>> On Sun, Jan 18, 2026 at 09:38:36AM +0100, Dirk Behme wrote:
>> [...]
>> > >  
>> > > +// The current helpers of load/store uses `{WRITE,READ}_ONCE()` hence the atomicity is only
>> > 
>> > uses -> use ?
>> > 
>> 
>> Will fix, thank you!
>> 
>> > > +// guaranteed against read-modify-write operations if the architecture supports native atomic RmW.
>> > > +#[cfg(CONFIG_ARCH_SUPPORTS_ATOMIC_RMW)]
>> > > +impl AtomicImpl for *const c_void {
>> > > +    type Delta = isize;
>> > > +}
>> > 
>> > Are all users of this guarded with CONFIG_ARCH_SUPPORTS_ATOMIC_RMW as
>> > well? Or do we want (need?) to cover the
>> 
>> No, the users don't need to guard with CONFIG_ARCH_SUPPORTS_ATOMIC_RMW,
>> the purpose of this #[cfg] is to avoid surprise that when
>> CONFIG_ARCH_SUPPORTS_ATOMIC_RMW=n arch supports Rust, when that happens,
>> we need to add the support to the helpers of i8/i16/ptr.
>> 
>
> Hmm... I guess at this moment, I probably should do
>
> #[cfg(not(CONFIG_ARCH_SUPPORTS_ATOMIC_RMW))]
> static_assert!(false,
>                "Support of architectures that don't have native atomic needs to implement helpers in atomic_ext.c");
>
> I can add a patch in the next version if it looks good to everyone.

I think this is a great idea!

By the way, did you know about `cfg!` [1]?:

    static_assert!(
        cfg!(CONFIG_ARCH_SUPPORTS_ATOMIC_RMW),
        "Support of architectures that don't have native atomic needs to implement helpers in atomic_ext.c",
    );


[1]: https://doc.rust-lang.org/core/macro.cfg.html

Cheers,
Benno