linux-kernel - [PATCH v4 07/10] rust: sync: atomic: Add Atomic<u{32,64}>

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Message-Id: <20250609224615.27061-8-boqun.feng@gmail.com>
Date: Mon,  9 Jun 2025 15:46:12 -0700
From: Boqun Feng <boqun.feng@...il.com>
To: linux-kernel@...r.kernel.org,
	rust-for-linux@...r.kernel.org,
	lkmm@...ts.linux.dev,
	linux-arch@...r.kernel.org
Cc: 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>,
	Wedson Almeida Filho <wedsonaf@...il.com>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Lyude Paul <lyude@...hat.com>,
	Ingo Molnar <mingo@...nel.org>,
	Mitchell Levy <levymitchell0@...il.com>,
	"Paul E. McKenney" <paulmck@...nel.org>,
	"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Thomas Gleixner" <tglx@...utronix.de>
Subject: [PATCH v4 07/10] rust: sync: atomic: Add Atomic<u{32,64}>

Add generic atomic support for basic unsigned types that have an
`AtomicImpl` with the same size and alignment.

Unit tests are added including Atomic<i32> and Atomic<i64>.

Signed-off-by: Boqun Feng <boqun.feng@...il.com>
---
 rust/kernel/sync/atomic.rs | 83 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)

diff --git a/rust/kernel/sync/atomic.rs b/rust/kernel/sync/atomic.rs
index a01e44eec380..9039591b4d46 100644
--- a/rust/kernel/sync/atomic.rs
+++ b/rust/kernel/sync/atomic.rs
@@ -22,3 +22,86 @@
 
 pub use generic::Atomic;
 pub use ordering::{Acquire, Full, Relaxed, Release};
+
+// SAFETY: `u64` and `i64` has the same size and alignment.
+unsafe impl generic::AllowAtomic for u64 {
+    type Repr = i64;
+
+    fn into_repr(self) -> Self::Repr {
+        self as _
+    }
+
+    fn from_repr(repr: Self::Repr) -> Self {
+        repr as _
+    }
+}
+
+impl generic::AllowAtomicArithmetic for u64 {
+    type Delta = u64;
+
+    fn delta_into_repr(d: Self::Delta) -> Self::Repr {
+        d as _
+    }
+}
+
+// SAFETY: `u32` and `i32` has the same size and alignment.
+unsafe impl generic::AllowAtomic for u32 {
+    type Repr = i32;
+
+    fn into_repr(self) -> Self::Repr {
+        self as _
+    }
+
+    fn from_repr(repr: Self::Repr) -> Self {
+        repr as _
+    }
+}
+
+impl generic::AllowAtomicArithmetic for u32 {
+    type Delta = u32;
+
+    fn delta_into_repr(d: Self::Delta) -> Self::Repr {
+        d as _
+    }
+}
+
+use crate::macros::kunit_tests;
+
+#[kunit_tests(rust_atomics)]
+mod tests {
+    use super::*;
+
+    // Call $fn($val) with each $type of $val.
+    macro_rules! for_each_type {
+        ($val:literal in [$($type:ty),*] $fn:expr) => {
+            $({
+                let v: $type = $val;
+
+                $fn(v);
+            })*
+        }
+    }
+
+    #[test]
+    fn atomic_basic_tests() {
+        for_each_type!(42 in [i32, i64, u32, u64] |v| {
+            let x = Atomic::new(v);
+
+            assert_eq!(v, x.load(Relaxed));
+        });
+    }
+
+    #[test]
+    fn atomic_arithmetic_tests() {
+        for_each_type!(42 in [i32, i64, u32, u64] |v| {
+            let x = Atomic::new(v);
+
+            assert_eq!(v, x.fetch_add(12, Full));
+            assert_eq!(v + 12, x.load(Relaxed));
+
+            x.add(13, Relaxed);
+
+            assert_eq!(v + 25, x.load(Relaxed));
+        });
+    }
+}
-- 
2.39.5 (Apple Git-154)