linux-kernel - [tip: locking/core] rust: helpers: Add i8/i16 atomic_read_acquire/atomic_set

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Message-ID: <176830140877.510.15255115321235116733.tip-bot2@tip-bot2>
Date: Tue, 13 Jan 2026 10:50:08 -0000
From: "tip-bot2 for FUJITA Tomonori" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: FUJITA Tomonori <fujita.tomonori@...il.com>, Gary Guo <gary@...yguo.net>,
 Joel Fernandes <joelagnelf@...dia.com>, Boqun Feng <boqun.feng@...il.com>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: locking/core] rust: helpers: Add i8/i16
 atomic_read_acquire/atomic_set_release helpers

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     2cc3d5d6adbee058858f2e66de701a203b032746
Gitweb:        https://git.kernel.org/tip/2cc3d5d6adbee058858f2e66de701a203b032746
Author:        FUJITA Tomonori <fujita.tomonori@...il.com>
AuthorDate:    Thu, 11 Dec 2025 20:38:23 +09:00
Committer:     Boqun Feng <boqun.feng@...il.com>
CommitterDate: Fri, 09 Jan 2026 19:01:40 +08:00

rust: helpers: Add i8/i16 atomic_read_acquire/atomic_set_release helpers

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 0000000..1fb6241
--- /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 79c7276..15d7557 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"