linux-kernel - Re: [PATCH v5 1/5] rust: implement `kernel::sync::Refcount`

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Message-Id: <DBXI970JGY3S.35LGOC2FO3EOE@nvidia.com>
Date: Sat, 09 Aug 2025 10:27:51 +0900
From: "Alexandre Courbot" <acourbot@...dia.com>
To: "Gary Guo" <gary@...nel.org>, "Miguel Ojeda" <ojeda@...nel.org>, "Alex
 Gaynor" <alex.gaynor@...il.com>, "Boqun Feng" <boqun.feng@...il.com>, "Gary
 Guo" <gary@...yguo.net>, Björn Roy Baron
 <bjorn3_gh@...tonmail.com>, "Benno Lossin" <lossin@...nel.org>, "Andreas
 Hindborg" <a.hindborg@...nel.org>, "Alice Ryhl" <aliceryhl@...gle.com>,
 "Trevor Gross" <tmgross@...ch.edu>, "Danilo Krummrich" <dakr@...nel.org>,
 "Will Deacon" <will@...nel.org>, "Peter Zijlstra" <peterz@...radead.org>,
 "Mark Rutland" <mark.rutland@....com>, "Tamir Duberstein"
 <tamird@...il.com>, "Ingo Molnar" <mingo@...nel.org>, "Mitchell Levy"
 <levymitchell0@...il.com>, "Lyude Paul" <lyude@...hat.com>, "Wedson Almeida
 Filho" <wedsonaf@...il.com>, "Viresh Kumar" <viresh.kumar@...aro.org>
Cc: <rust-for-linux@...r.kernel.org>, "Fiona Behrens" <me@...enk.dev>,
 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 1/5] rust: implement `kernel::sync::Refcount`

Hi Gary,

On Thu Jul 24, 2025 at 8:32 AM JST, Gary Guo wrote:
<snip>
> +pub struct Refcount(Opaque<bindings::refcount_t>);
> +
> +impl Refcount {
> +    /// Construct a new [`Refcount`] from an initial value.
> +    ///
> +    /// The initial value should be non-saturated.
> +    #[inline]
> +    pub fn new(value: i32) -> Self {
> +        build_assert!(value >= 0, "initial value saturated");

Given that `inc` will WARN if the refcount is `0`, do we want to accept
`0` here?