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Wed, 31 Dec 2025 04:22:42 -0800 (PST) Date: Wed, 31 Dec 2025 12:22:29 +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=1210; i=aliceryhl@google.com; h=from:subject:message-id; bh=x48g//vEaovaCGc/+3V+kdS96OVZQrdlR7cVmTcJM3Y=; b=owEBbQKS/ZANAwAKAQRYvu5YxjlGAcsmYgBpVRWLpYz+qsgfDBCA957maLrU5abZ/AV0KNPf2 x2dVJo4CRyJAjMEAAEKAB0WIQSDkqKUTWQHCvFIvbIEWL7uWMY5RgUCaVUViwAKCRAEWL7uWMY5 RpbRD/0SaSpBYAhj01HuT6p1Sh0F3HjDBRU4CbZou0WZNZ4WriLhGAdf+MIIjlEt+5DLcmae+YX 27BXKetHb+p7wJar0/d6qrTf/TQHUwmCyaL950x8UvyGKZjIVa/TCNx64b/oJobA7VmOtuNtFHr krbCJy/HsPCYdyTfYX7LhHPaeMGMOZDlhS5MWUgWYmbEo0Jx4LgSaNXEzhQpnmDg88F1vPMjjhW no8A0idLJ5umHWtXn0h1OKB0XvRpQTVwo+JZsNk8M/8cFdcvbJQxHrbwuTEGFaIkb01dRY1Ntdf 01rcHfSx1yu4iyuNDwnwXWxKy6Gk0DisKWSz0r+uqQjJIH5yLwLiZ+oKtGUU50CoT+p7D3XX7ee NQYmTAfFErPyMycWpb0rdPLebSye3a2RtXxOO0cCLsGAzKsadQYt9Qyiz/SRaSuGAxprP+2SaA1 tYW2y41LKbfKByd3v4AXtcjuXykAoAaaZnFcRcSSFxaaLuuAzS1kB42Gdu92hVpMPWBZ16h/RLM lf/wjXI1jEitSsib4IBK188r4m5IDfIk6q5hlJM5cvNgfzDpsOBNpz0qvCLfTiIP01+JvimWH6n S+0cvXpMJQIc85ahkyeZd7IPV6qu+FHl1qL2ZnTHNJ0ktF6I2ONB+Fvhbz5Z7ky5OYO5MmZfBJO 4eEFKw4YUaLnpqg== X-Mailer: b4 0.14.2 Message-ID: <20251231-rwonce-v1-5-702a10b85278@google.com> Subject: [PATCH 5/5] rust: fs: 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_042245_163784_978115F1 X-CRM114-Status: GOOD ( 12.15 ) 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 `f_flags` field. Signed-off-by: Alice Ryhl --- rust/kernel/fs/file.rs | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/rust/kernel/fs/file.rs b/rust/kernel/fs/file.rs index 23ee689bd2400565223181645157d832a836589f..6b07f08e7012f512e53743266096ce0076d29e1c 100644 --- a/rust/kernel/fs/file.rs +++ b/rust/kernel/fs/file.rs @@ -335,12 +335,8 @@ pub fn cred(&self) -> &Credential { /// The flags are a combination of the constants in [`flags`]. #[inline] pub fn flags(&self) -> u32 { - // This `read_volatile` is intended to correspond to a READ_ONCE call. - // - // SAFETY: The file is valid because the shared reference guarantees a nonzero refcount. - // - // FIXME(read_once): Replace with `read_once` when available on the Rust side. - unsafe { core::ptr::addr_of!((*self.as_ptr()).f_flags).read_volatile() } + // SAFETY: The `f_flags` field of `struct file` is readable with `READ_ONCE`. + unsafe { kernel::sync::READ_ONCE(&raw const (*self.as_ptr()).f_flags) } } } -- 2.52.0.351.gbe84eed79e-goog