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rust: sync: atomic: Add atomic bool support via i8 representation

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Add `bool` support, `Atomic<bool>` 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 <fujita.tomonori@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20260101034922.2020334-2-fujita.tomonori@gmail.com
This commit is contained in:
FUJITA Tomonori 2026-01-01 12:49:21 +09:00 committed by Boqun Feng
parent 584f286f82
commit 06bd0e52bf
1 changed files with 11 additions and 0 deletions
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11
rust/kernel/sync/atomic/predefine.rs
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@ -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::<bool>() == size_of::<i8>());
static_assert!(align_of::<bool>() == align_of::<i8>());
// 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 {