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charset=UTF-8 Date: Tue, 24 Feb 2026 11:08:19 +0900 Message-Id: To: "Joel Fernandes" , "Eliot Courtney" , , "Miguel Ojeda" , "Boqun Feng" , "Gary Guo" , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , "Benno Lossin" , "Andreas Hindborg" , "Alice Ryhl" , "Trevor Gross" , "Danilo Krummrich" , "Alexandre Courbot" Cc: "Dave Airlie" , "Daniel Almeida" , "Koen Koning" , , , , "Nikola Djukic" , "dri-devel" Subject: Re: [PATCH v10 5/8] rust: clist: Add support to interface with C linked lists From: "Eliot Courtney" X-Mailer: aerc 0.21.0-0-g5549850facc2 References: <20260218205507.689429-1-joelagnelf@nvidia.com> <20260218205507.689429-6-joelagnelf@nvidia.com> In-Reply-To: X-ClientProxiedBy: TY4P286CA0046.JPNP286.PROD.OUTLOOK.COM (2603:1096:405:36e::13) To SN1PR12MB2368.namprd12.prod.outlook.com (2603:10b6:802:32::23) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL0PR12MB2353:EE_|MN6PR12MB8490:EE_ X-MS-Office365-Filtering-Correlation-Id: 539544c7-7309-4fc5-fe1e-08de73499657 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|10070799003|1800799024|366016|376014|7416014|921020; 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>>> + >>> + // Calculate offset and create `CList`. >>> + const OFFSET: usize =3D ::core::mem::offset_of!($c_type, $($fi= eld).+); >>> + $crate::ffi::clist::CList::<$rust_type, OFFSET>::from_raw($hea= d) >>> + }}; >>> +} >>=20 >> This uses offset_of! in a way that requires the offset_of_nested >> feature, so it doesn't build in rust 1.78.0. The feature is already >> added to rust_allowed_features, so I think it's ok to add >> #![feature(offset_of_nested)]. > > Maybe I am missing something, but why should the feature be gated behind > that if all compiler versions (>=3D 1.78) support it either in a stable w= ay > or via an unstable feature flag? I think that's why it's in rust_allowed_features. IIUC that's where we put unstable features that are stable enough in all supported compiler versions to be used. But, rust_allowed_features doesn't apply to the code here, so you'd have to add an allow to rust/kernel/lib.rs.