linux-kernel - [PATCH 11/36] rust: helpers: Add i8/i16 atomic try

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Message-ID: <20260111120209.6133-9-boqun.feng@gmail.com>
Date: Sun, 11 Jan 2026 20:01:44 +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>,
	Boqun Feng <boqun.feng@...il.com>
Subject: [PATCH 11/36] rust: helpers: Add i8/i16 atomic try_cmpxchg helpers

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

Add i8/i16 atomic try_cmpxchg helpers that call try_cmpxchg() macro
implementing atomic try_cmpxchg using architecture-specific
instructions.

[boqun: Add comments explaining CONFIG_ARCH_SUPPORTS_ATOMIC_RMW and use
try_cmpxchg() instead of raw_try_cmpxchg()]

Signed-off-by: FUJITA Tomonori <fujita.tomonori@...il.com>
Signed-off-by: Boqun Feng <boqun.feng@...il.com>
Link: https://patch.msgid.link/20251227115951.1424458-2-fujita.tomonori@gmail.com
---
 rust/helpers/atomic_ext.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/rust/helpers/atomic_ext.c b/rust/helpers/atomic_ext.c
index 76e392c39c7b..5ee127f1cc80 100644
--- a/rust/helpers/atomic_ext.c
+++ b/rust/helpers/atomic_ext.c
@@ -90,3 +90,20 @@ __rust_helper s16 rust_helper_atomic_i16_xchg_relaxed(s16 *ptr, s16 new)
 {
 	return xchg_relaxed(ptr, new);
 }
+
+/*
+ * try_cmpxchg helpers depend on ARCH_SUPPORTS_ATOMIC_RMW and on the
+ * architecture provding try_cmpxchg() support for i8 and i16.
+ *
+ * The architectures that currently support Rust (x86_64, armv7,
+ * arm64, riscv, and loongarch) satisfy these requirements.
+ */
+__rust_helper bool rust_helper_atomic_i8_try_cmpxchg(s8 *ptr, s8 *old, s8 new)
+{
+	return try_cmpxchg(ptr, old, new);
+}
+
+__rust_helper bool rust_helper_atomic_i16_try_cmpxchg(s16 *ptr, s16 *old, s16 new)
+{
+	return try_cmpxchg(ptr, old, new);
+}
-- 
2.51.0