From 06bd0e52bfd78eae1c7dd5db163ce64161b495e7 Mon Sep 17 00:00:00 2001 From: FUJITA Tomonori Date: Thu, 1 Jan 2026 12:49:21 +0900 Subject: [PATCH] rust: sync: atomic: Add atomic bool support via i8 representation Add `bool` support, `Atomic` by using `i8` as its underlying representation. Rust specifies that `bool` has size 1 and alignment 1 [1], so it matches `i8` on layout; keep `static_assert!()` checks to enforce this assumption at build time. [boqun: Remove the unnecessary impl AtomicImpl for bool] Link: https://doc.rust-lang.org/reference/types/boolean.html [1] Signed-off-by: FUJITA Tomonori Reviewed-by: Gary Guo Signed-off-by: Boqun Feng Link: https://patch.msgid.link/20260101034922.2020334-2-fujita.tomonori@gmail.com --- rust/kernel/sync/atomic/predefine.rs | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/rust/kernel/sync/atomic/predefine.rs b/rust/kernel/sync/atomic/predefine.rs index 248d26555ccf6..3fc99174b0869 100644 --- a/rust/kernel/sync/atomic/predefine.rs +++ b/rust/kernel/sync/atomic/predefine.rs @@ -5,6 +5,17 @@ use crate::static_assert; use core::mem::{align_of, size_of}; +// Ensure size and alignment requirements are checked. +static_assert!(size_of::() == size_of::()); +static_assert!(align_of::() == align_of::()); + +// SAFETY: `bool` has the same size and alignment as `i8`, and Rust guarantees that `bool` has +// only two valid bit patterns: 0 (false) and 1 (true). Those are valid `i8` values, so `bool` is +// round-trip transmutable to `i8`. +unsafe impl super::AtomicType for bool { + type Repr = i8; +} + // SAFETY: `i8` has the same size and alignment with itself, and is round-trip transmutable to // itself. unsafe impl super::AtomicType for i8 { -- 2.47.3