Re: [PATCH 2/2] rust: sync: atomic: Add atomic operation helpers over raw pointers

[Boqun Feng]

On Wed, Jan 21, 2026 at 01:36:04PM +0100, Marco Elver wrote:
[..]
> >
> > > However this will mean that Rust code will have one more ordering than the C
> > > API, so I am keen on knowing how Boqun, Paul, Peter and others think about this.
> >
> > On that point, my suggestion would be to use the standard LKMM naming
> > such as rcu_dereference() or READ_ONCE().

I don't think we should confuse Rust users that `READ_ONCE()` has
dependency orderings but `atomc_load()` doesn't. They are the same on
the aspect. One of the reasons that I don't want to introduce
rcu_dereference() and READ_ONCE() on Rust side is exactly this, they are
the same at LKMM level, so should not be treated differently.

> >
> > I'm told that READ_ONCE() apparently has stronger guarantees than an
> > atomic consume load, but I'm not clear on what they are.
> 
> It's also meant to enforce ordering through control-dependencies, such as:
> 
>    if (READ_ONCE(x)) WRITE_ONCE(y, 1);

Note that it also applies to atomic_read() and atomic_set() as well.

Regards,
Boqun