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Date: Mon, 16 Feb 2026 00:28:02 +0100
Message-Id: <DGFXBHXTR8YS.3NUDRE3ZKV7Y6@kernel.org>
Cc: <rust-for-linux@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] rust: sync: add lazy initialization methods to SetOnce
From: "Benno Lossin" <lossin@kernel.org>
To: "Andreas Hindborg" <a.hindborg@kernel.org>, "Miguel Ojeda"
 <ojeda@kernel.org>, "Boqun Feng" <boqun.feng@gmail.com>, "Gary Guo"
 <gary@garyguo.net>, =?utf-8?q?Bj=C3=B6rn_Roy_Baron?=
 <bjorn3_gh@protonmail.com>, "Alice Ryhl" <aliceryhl@google.com>, "Trevor
 Gross" <tmgross@umich.edu>, "Danilo Krummrich" <dakr@kernel.org>
X-Mailer: aerc 0.21.0
References: <20260215-set-once-lazy-v1-1-6f5bd2efda11@kernel.org>
In-Reply-To: <20260215-set-once-lazy-v1-1-6f5bd2efda11@kernel.org>

On Sun Feb 15, 2026 at 9:27 PM CET, Andreas Hindborg wrote:
> @@ -76,10 +79,46 @@ pub fn as_ref(&self) -> Option<&T> {
>          }
>      }
> =20
> +    /// Get a reference to the contained object, or populate the [`SetOn=
ce`]
> +    /// with the value returned by `callable` and return a reference to =
that
> +    /// object.
> +    pub fn as_ref_or_populate_with(&self, callable: impl FnOnce() -> Res=
ult<T>) -> Result<&T> {

I would name the argument `create`, but not `callable`. Same below.

Cheers,
Benno

> +        if !self.populate_with(callable)? {
> +            while self.init.load(Acquire) !=3D 2 {
> +                core::hint::spin_loop();
> +            }
> +        }