From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f73.google.com (mail-wr1-f73.google.com [209.85.221.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E5635315D36 for ; Wed, 31 Dec 2025 12:22:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767183767; cv=none; b=t8P54gZh7PLGxDX++jP/IBKuB/1ii9kPr1BbWK2xRAWRGtRsV1rXw/Z31GqWY9WHUw/hoAcI42JG/nlAWQKm9+M4lW/YEfWOh6GqQwqwOY+K0fW4QP8k0lwI2nmABf8E9ESbjja6slc26YlKWhob1nAM3FZB77viFPJusdZnog4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767183767; c=relaxed/simple; bh=x48g//vEaovaCGc/+3V+kdS96OVZQrdlR7cVmTcJM3Y=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=g/O67RZRuvHWYWQgExXMuZBK6elFPYXPY9G2loMkXp76ZxNiF4kB2txUcR+OZbC5lF28GZOQ8rS5UoELAkUqkpkPlditDD6/8xY2w6qUlJrpzgvn8gs2OsgdczDNccdHCMA9BnHdHOJyATXcegJdyj7rFrcc4r+UyYTLpvl+29o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--aliceryhl.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=rXg+fj/D; arc=none smtp.client-ip=209.85.221.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--aliceryhl.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="rXg+fj/D" Received: by mail-wr1-f73.google.com with SMTP id ffacd0b85a97d-430f8866932so8713405f8f.1 for ; Wed, 31 Dec 2025 04:22:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1767183763; x=1767788563; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=EnX+YiWBwSFj03NZe+M6b1I0lykasXzPK5veF6o26Xk=; b=rXg+fj/DzoTvLQUq1C+NqmI1l/Dv9/E+2MpEhMt9Bn2phj0jP+SEVHcy6DFdj25ZWT cUZnz/qO1Qjs6y8pbxud7nGfmNScImOxjXZtq0ysNMkYcUmVxJTMi9HqajRH89WZDJPp D4n08kz2zhlNVxK5fLBL2MbnBu36uVh8B50QgJUpIjy2Ln2ixFUb9wkTubZUR2z5s0tU l6+mFPAmw4nGWooXRhLE3pmb7yHtaNG5Ilo6WykD0NpSojQ5s/1wggb/ZB/NfVTawK/x 5DG/FXxuiw4SnZ0HBZkOh4NSj4bScSQfDWK4NLUnyqqdHvOXZ0FrIU8hGYtakERRt/Gv 0l1g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1767183763; x=1767788563; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=EnX+YiWBwSFj03NZe+M6b1I0lykasXzPK5veF6o26Xk=; b=Nw7ESNF1o3zcR2CGjGv//dFOEVVzRkKxbLam/wkY71yQm06z9jgd7GDDoRMfWmXwLK w6BaaviYc/KB57AX2UOJ5P5tqGKMGkQeENREECp+0GMLVrlzpYrn/72/zZhjFopQloaE z9bTudH181TBLaUl00EGkU2lvEb9NjvvpODBfifW9F2I8uqSKNxQSXFVAnk6FjpIfg5C 71nMKQJ07vMVfbhF2yBgE/FLGP4im9ttC1RPwa9Z+2dms7D+2tNiEcF+oqjp+qvyuIAZ 2fH18KRWv8IPd0W2o4ITPtZGB4y8g059+e21vxPLb10bvC/Q6GbHrQSqPrC/XPk8uDj6 +JmA== X-Forwarded-Encrypted: i=1; AJvYcCXguSFgL3dFmVKJzZ8M65vuNx9GYeyjePpOzDV2icyFjgSvTi7fxZmcCd3yUdHt/L+TG2iF7YHoN6zlo9Cb4A==@vger.kernel.org X-Gm-Message-State: AOJu0YyVeZUGjtY1uRfGijQuFqjqzvnx8Yven2EPT6koTiLohbhupNjt 7/8V9oD75uhZhAkXdyzzsx08usqIdzDztCFd1QN2sZuYj2J1MOMebD39MadDey0vASZGZS+bEsH mThft3C579U1ShHNpEQ== X-Google-Smtp-Source: AGHT+IEVvKcXr6CgV/sO/SopdsqbSp5OU9ou7XeJWfmPxsy3aUaKE2cdpBZhPeJYGAC28ivLbvgGuv+puag4k9w= X-Received: from wro8.prod.google.com ([2002:a05:6000:41c8:b0:432:5cc6:c7ec]) (user=aliceryhl job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6000:40db:b0:42c:b8fd:21b3 with SMTP id ffacd0b85a97d-4324e70b2c0mr47793415f8f.57.1767183762838; 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> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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" 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