Re: [PATCH v6 3/9] rust: sync: atomic: Add ordering annotation types

Andreas Hindborg
2025-07-10T12:01:08Z

"Benno Lossin" <lossin@kernel.org> writes:

> On Thu Jul 10, 2025 at 8:00 AM CEST, Boqun Feng wrote:
>> Preparation for atomic primitives. Instead of a suffix like _acquire, a
>> method parameter along with the corresponding generic parameter will be
>> used to specify the ordering of an atomic operations. For example,
>> atomic load() can be defined as:
>>
>> impl<T: ...> Atomic<T> {
>> pub fn load<O: AcquireOrRelaxed>(&self, _o: O) -> T { ... }
>> }
>>
>> and acquire users would do:
>>
>> let r = x.load(Acquire);
>>
>> relaxed users:
>>
>> let r = x.load(Relaxed);
>>
>> doing the following:
>>
>> let r = x.load(Release);
>>
>> will cause a compiler error.
>>
>> Compared to suffixes, it's easier to tell what ordering variants an
>> operation has, and it also make it easier to unify the implementation of
>> all ordering variants in one method via generic. The `TYPE` associate
>> const is for generic function to pick up the particular implementation
>> specified by an ordering annotation.
>>
>> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
>> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
>
> One naming comment below, with that fixed:
>
> Reviewed-by: Benno Lossin <lossin@kernel.org>
>
>> ---
>> rust/kernel/sync/atomic.rs | 3 +
>> rust/kernel/sync/atomic/ordering.rs | 97 +++++++++++++++++++++++++++++
>> 2 files changed, 100 insertions(+)
>> create mode 100644 rust/kernel/sync/atomic/ordering.rs
>
>> +/// The trait bound for annotating operations that support any ordering.
>> +pub trait Any: internal::Sealed {
>
> I don't like the name `Any`, how about `AnyOrdering`? Otherwise we
> should require people to write `ordering::Any` because otherwise it's
> pretty confusing.

I agree with this observation.

Best regards,
Andreas Hindborg