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Wed, 31 Dec 2025 04:22:41 -0800 (PST) Date: Wed, 31 Dec 2025 12:22:28 +0000 In-Reply-To: <20251231-rwonce-v1-0-702a10b85278@google.com> Mime-Version: 1.0 References: <20251231-rwonce-v1-0-702a10b85278@google.com> X-Developer-Key: i=aliceryhl@google.com; a=openpgp; fpr=49F6C1FAA74960F43A5B86A1EE7A392FDE96209F X-Developer-Signature: v=1; a=openpgp-sha256; l=1228; i=aliceryhl@google.com; h=from:subject:message-id; bh=dWGhxjFk0H0ccZ8Z0LvyX4T5xP2vhqe9w9Pjy9Iy9EA=; b=owEBbQKS/ZANAwAKAQRYvu5YxjlGAcsmYgBpVRWLGkM6ekaGvNs/GppoXyA8q6kxlkpqLewuW 7WNKhbTKjqJAjMEAAEKAB0WIQSDkqKUTWQHCvFIvbIEWL7uWMY5RgUCaVUViwAKCRAEWL7uWMY5 RtLUEACKkaSaNK/TcJXYBxaQi+3v3CPDHRjWTgRzkBlZ2cipngBrd+Bwm5aNQr6HLLA2wljr5zB sd8yJUc9TZdLiWbispUZaLCxJC+XAMVad9CXiS98PYq5H0Hv98uxbgcFI4T3nuHqM/xrG4OBMqR d9jwZii4XhRij0gUrPqQYAqX3+sb174Ah2h6tS1WLllr/7oegCZFedCpoObQ7JF9OwSXtT5VevH R2ZDKva3GoKaG0vo428LZXH/UDDFPKUn6o0Y1whhaRXdzIG5we6N/H53PjF2Q+OC2kHDHtqgKea xjKnfDl8tJ5TAjd69k/mBPk3xHvVo/vIbXfL35oFTix2yk1n8kcuv1Zx0+Qbv6gF1FSr5sn9Yot z3DlseF+Q4w5zWKbGVngm4+kn9Lo6gew72+hoQ8C2n7b9mGKUkCIqmNHamdglZznxgfrHGI8imv Lkz8hP73DNqX6vhQblP3+Fxt/SN84uREUef+vAAyVKFAIp7SprtvVzputk+BQAw+YVR+0f8QLLn eErdIcXGjyGhtXHOc3Gp79iwy56k9avNJ3qKMHDpuuC1LPYW4FH+9lKwRwkh6qmqJXW5Wd6RnE0 rUhuFmIzHmZwLTF8u3QbBC9TYTfct5eLCQac3dju/Lnq2VWuei0fDBQanQibHCkKnD/nVST47AS Hq8sRXqSOcbvtBQ== X-Mailer: b4 0.14.2 Message-ID: <20251231-rwonce-v1-4-702a10b85278@google.com> Subject: [PATCH 4/5] rust: hrtimer: use READ_ONCE instead of read_volatile From: Alice Ryhl To: Boqun Feng , Will Deacon , Peter Zijlstra Cc: Richard Henderson , Matt Turner , Magnus Lindholm , Catalin Marinas , Miguel Ojeda , Gary Guo , "=?utf-8?q?Bj=C3=B6rn_Roy_Baron?=" , Benno Lossin , Andreas Hindborg , Trevor Gross , Danilo Krummrich , Mark Rutland , FUJITA Tomonori , Frederic Weisbecker , Lyude Paul , Thomas Gleixner , Anna-Maria Behnsen , John Stultz , Stephen Boyd , Alexander Viro , Christian Brauner , Jan Kara , linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, rust-for-linux@vger.kernel.org, linux-fsdevel@vger.kernel.org, Alice Ryhl Content-Type: text/plain; charset="utf-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251231_042243_797235_991F5178 X-CRM114-Status: GOOD ( 11.73 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Using `READ_ONCE` is the correct way to read the `node.expires` field. Signed-off-by: Alice Ryhl --- rust/kernel/time/hrtimer.rs | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs index 856d2d929a00892dc8eaec63cebdf547817953d3..e2b7a26f8aade972356c3eb5f6489bcda3e2e849 100644 --- a/rust/kernel/time/hrtimer.rs +++ b/rust/kernel/time/hrtimer.rs @@ -239,11 +239,9 @@ pub fn expires(&self) -> HrTimerInstant // - Timers cannot have negative ktime_t values as their expiration time. // - There's no actual locking here, a racy read is fine and expected unsafe { - Instant::from_ktime( - // This `read_volatile` is intended to correspond to a READ_ONCE call. - // FIXME(read_once): Replace with `read_once` when available on the Rust side. - core::ptr::read_volatile(&raw const ((*c_timer_ptr).node.expires)), - ) + Instant::from_ktime(kernel::sync::READ_ONCE( + &raw const (*c_timer_ptr).node.expires, + )) } } } -- 2.52.0.351.gbe84eed79e-goog