Re: [PATCH 6.12.y] rust: block: `allow(deprecated)` for `fetch_update` for Rust >= 1.99.0

Re: [PATCH 6.12.y] rust: block: `allow(deprecated)` for `fetch_update` for Rust >= 1.99.0

[Miguel Ojeda]

On Sat, Jul 18, 2026 at 8:23 PM Miguel Ojeda <ojeda@kernel.org> wrote:
>
> Starting with Rust 1.99.0 (expected 2026-10-01), the
> `Atomic*::fetch_update` method is deprecated, with the compiler suggesting
> the `try_update` alias instead:
>
>     error: use of deprecated method `core::sync::atomic::Atomic::<u64>::fetch_update`: renamed to `try_update` for consistency
>        --> rust/kernel/block/mq/request.rs:206:22
>         |
>     206 |     let old = target.fetch_update(Ordering::Relaxed, Ordering::Relaxed, |x| Some(op(x)));
>         |                      ^^^^^^^^^^^^
>         |
>         = note: `-D deprecated` implied by `-D warnings`
>         = help: to override `-D warnings` add `#[allow(deprecated)]`
>     help: replace the use of the deprecated method
>         |
>     206 -     let old = target.fetch_update(Ordering::Relaxed, Ordering::Relaxed, |x| Some(op(x)));
>     206 +     let old = target.try_update(Ordering::Relaxed, Ordering::Relaxed, |x| Some(op(x)));
>         |
>
> The deprecation was added in Rust 1.95.0 [1], but only triggers starting
> with Rust 1.99.0.
>
> However, we cannot use the alias since our minimum in 6.12.y is Rust
> 1.78.0 -- `try_update` was added in Rust 1.86.0 [2].
>
> Thus just allow the lint.
>
> Cc: Andreas Hindborg <a.hindborg@kernel.org>
> Cc: Boqun Feng <boqun@kernel.org>
> Cc: Jens Axboe <axboe@kernel.dk>
> Link: https://github.com/rust-lang/rust/pull/148590 [1]
> Link: https://github.com/rust-lang/rust/pull/133829 [2]
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
> ---
> Warning: this is a 6.12.y-only patch -- I assume you prefer something
> local like this instead of backporting the commit that made this go away
> later with the move to `Refcount`.

Cc'ing stable here in the reply.

Cheers,
Miguel

Re: [PATCH 6.12.y] rust: block: `allow(deprecated)` for `fetch_update` for Rust >= 1.99.0

[Sasha Levin]

>> Warning: this is a 6.12.y-only patch -- I assume you prefer something
>> local like this instead of backporting the commit that made this go away
>> later with the move to `Refcount`.
>
> Cc'ing stable here in the reply.

Queued for 6.12, thanks.

-- 
Thanks,
Sasha