linux-kernel - [PATCH 05/36] rust: helpers: Add i8/i16 atomic_read_acquire/atomic_set

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Message-ID: <20260111120209.6133-3-boqun.feng@gmail.com>
Date: Sun, 11 Jan 2026 20:01:38 +0800
From: Boqun Feng <boqun.feng@...il.com>
To: "Peter Zijlstra" <peterz@...radead.org>,
	"Ingo Molnar" <mingo@...nel.org>
Cc: rust-for-linux@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Will Deacon" <will@...nel.org>,
	"Mark Rutland" <mark.rutland@....com>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	"Miguel Ojeda" <ojeda@...nel.org>,
	"Gary Guo" <gary@...yguo.net>,
	"Alice Ryhl" <aliceryhl@...gle.com>,
	"Andreas Hindborg" <a.hindborg@...nel.org>,
	"Benno Lossin" <lossin@...nel.org>,
	"Danilo Krummrich" <dakr@...nel.org>,
	FUJITA Tomonori <fujita.tomonori@...il.com>,
	Joel Fernandes <joelagnelf@...dia.com>,
	Boqun Feng <boqun.feng@...il.com>
Subject: [PATCH 05/36] rust: helpers: Add i8/i16 atomic_read_acquire/atomic_set_release helpers

From: FUJITA Tomonori <fujita.tomonori@...il.com>

Add helper functions to expose smp_load_acquire() and
smp_store_release() for i8 and i16 types.

The smp_load_acquire() and smp_store_release() macros require type
information (sizeof) to generate appropriate architecture-specific
memory ordering instructions. Therefore, separate helper functions are
needed for each type size.

These helpers expose different symbol names than their C counterparts
so they are split into atomic_ext.c instead of atomic.c. The symbol
names; atomic_[i8|i16]_read_acquire and atomic_[i8|i16]_set_release
makes the interface Rust/C clear, consistent with i32/i64.

These helpers will be used by the upcoming Atomic<i8> and Atomic<i16>
implementation to provide proper Acquire/Release semantics across all
architectures.

[boqun: Rename the functions from {load,store} to {read,set} to avoid
future adjustment]

Signed-off-by: FUJITA Tomonori <fujita.tomonori@...il.com>
Reviewed-by: Gary Guo <gary@...yguo.net>
Reviewed-by: Joel Fernandes <joelagnelf@...dia.com>
Signed-off-by: Boqun Feng <boqun.feng@...il.com>
Link: https://patch.msgid.link/20251211113826.1299077-2-fujita.tomonori@gmail.com
---
 rust/helpers/atomic_ext.c | 23 +++++++++++++++++++++++
 rust/helpers/helpers.c    |  1 +
 2 files changed, 24 insertions(+)
 create mode 100644 rust/helpers/atomic_ext.c

diff --git a/rust/helpers/atomic_ext.c b/rust/helpers/atomic_ext.c
new file mode 100644
index 000000000000..1fb624147aa4
--- /dev/null
+++ b/rust/helpers/atomic_ext.c
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <asm/barrier.h>
+
+__rust_helper s8 rust_helper_atomic_i8_read_acquire(s8 *ptr)
+{
+	return smp_load_acquire(ptr);
+}
+
+__rust_helper s16 rust_helper_atomic_i16_read_acquire(s16 *ptr)
+{
+	return smp_load_acquire(ptr);
+}
+
+__rust_helper void rust_helper_atomic_i8_set_release(s8 *ptr, s8 val)
+{
+	smp_store_release(ptr, val);
+}
+
+__rust_helper void rust_helper_atomic_i16_set_release(s16 *ptr, s16 val)
+{
+	smp_store_release(ptr, val);
+}
diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
index 79c72762ad9c..15d75578f459 100644
--- a/rust/helpers/helpers.c
+++ b/rust/helpers/helpers.c
@@ -8,6 +8,7 @@
  */
 
 #include "atomic.c"
+#include "atomic_ext.c"
 #include "auxiliary.c"
 #include "barrier.c"
 #include "binder.c"
-- 
2.51.0