linux-kernel - [PATCH] rust: cpumask: Mark CpumaskVar as transparent

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Message-ID: <20250812144215.64809-1-baptiste.lepers@gmail.com>
Date: Tue, 12 Aug 2025 16:42:11 +0200
From: Baptiste Lepers <baptiste.lepers@...il.com>
To: 
Cc: Baptiste Lepers <baptiste.lepers@...il.com>,
	stable@...r.kernel.org,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Yury Norov <yury.norov@...il.com>,
	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>,
	rust-for-linux@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] rust: cpumask: Mark CpumaskVar as transparent

Unsafe code in CpumaskVar's methods assumes that the type has the same
layout as `bindings::cpumask_var_t`. This is not guaranteed by
the default struct representation in Rust, but requires specifying the
`transparent` representation.

Fixes: 8961b8cb3099a ("rust: cpumask: Add initial abstractions")
Cc: stable@...r.kernel.org
Signed-off-by: Baptiste Lepers <baptiste.lepers@...il.com>
---
 rust/kernel/cpumask.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rust/kernel/cpumask.rs b/rust/kernel/cpumask.rs
index 3fcbff438670..05e1c882404e 100644
--- a/rust/kernel/cpumask.rs
+++ b/rust/kernel/cpumask.rs
@@ -212,6 +212,7 @@ pub fn copy(&self, dstp: &mut Self) {
 /// }
 /// assert_eq!(mask2.weight(), count);
 /// ```
+#[repr(transparent)]
 pub struct CpumaskVar {
     #[cfg(CONFIG_CPUMASK_OFFSTACK)]
     ptr: NonNull<Cpumask>,
-- 
2.43.0