[RFC 2/2] rust: sync: Add atomic support

[Kent Overstreet]

On Sun, Jun 16, 2024 at 10:30:03AM -0700, Boqun Feng wrote:
> I think the disagreement here is not non-generic atomic vs generic
> atomic, it's pure generic atomic vs. AtomicI{32,64} etc + generic
> atomic. I said multiple times that I'm OK with generic atomics if there
> are real users, just I'm not sure it's something we want to do right now
> (or we have enough information to go fully on that direction). And I
> think it's fine to have non-generic atomic and generic atomic coexist.

Well, having the generic interface from the start does matter, that's
what we (myself included) want to code to.

No need to overcomplicate it, just
Atomic<u8>
Atomic<u16>

etc...

As long as that's available, the internal implementation shouldn't have
to change.