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Fri, 29 May 2026 14:56:02 -0700 Date: Fri, 29 May 2026 14:56:01 -0700 From: Nicolin Chen To: Pranjal Shrivastava CC: , , , , "Joerg Roedel" , Will Deacon , Bjorn Helgaas , David Woodhouse , Lu Baolu , Robin Murphy , "Suravee Suthikulpanit" , Jason Gunthorpe , David Matlack , Samiullah Khawaja , Daniel Mentz , Pasha Tatashin , Mostafa Saleh Subject: Re: [PATCH v6 3/6] PCI/ATS: Mandate checking pci_ats_supported() before pci_prepare_ats() Message-ID: References: <20260529111208.387412-1-praan@google.com> <20260529111208.387412-4-praan@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20260529111208.387412-4-praan@google.com> X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ5PEPF00000205:EE_|SJ2PR12MB8782:EE_ X-MS-Office365-Filtering-Correlation-Id: 64dfbdc1-590f-4fd6-c38c-08debdcd1e0c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|7416014|82310400026|36860700016|56012099006|11063799006|4143699003|6133799003|22082099003|18002099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: FSfUpskq3rncaLWA/ngOCS/C4XAXyBkfzMBPFddhU6jrPiTpC97IDqkMtIR5rJ58zD1+b+XinCNYpdKPF/iSaSez106psNBaL9Yhg/pGPk4HRJY+gUs2cUJ4QfNM6eab8mUizfSoALoL/bj6GK47WdfZip2ZNeeiMuf6P1IWH0+9s68PjTyAxfY+6+i/kuAh01MVV0jSiy6CJDIZNb7H8PcaDBeYPYpHx63lo3rRe5bGYRRJxXt5aHPdf3XvclzL4+u2PWDJZG7CBQY8YbI6w4iulT1jRxkuqizHFEj8TpdMLp38YGtPZCdub7pzRttTX4esZgqAw+DdJ7AQpHRM7LU6xE2srVW3Ze4jHsN4YhkeJAzJxm9yx4GoSRh/1KSOqSUHMX7LHw2icHi87GIJ7vrB8WtZlqHAy1QG7H3Q1k+vppeSTrLeHzzsJCjC9UhX X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 May 2026 21:56:20.2953 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 64dfbdc1-590f-4fd6-c38c-08debdcd1e0c X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: SJ5PEPF00000205.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR12MB8782 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260529_145629_593754_C1FD8EEB X-CRM114-Status: GOOD ( 11.72 ) 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 On Fri, May 29, 2026 at 11:12:05AM +0000, Pranjal Shrivastava wrote: > Currently, pci_prepare_ats() internally calls pci_ats_supported() and > returns -EINVAL if the device does not support ATS. While this provides > a silent safety check, it conflates support detection with configuration. > > Update pci_prepare_ats() to wrap the internal pci_ats_supported check in > a WARN_ON(). This mandates all callers to call pci_prepare_ats() only if > the function supports ATS. > > Update the function documentation to mention that callers must verify > ATS support (via pci_ats_supported()) before calling pci_prepare_ats(). > > Suggested-by: Baolu Lu > Signed-off-by: Pranjal Shrivastava Sashiko pointed out a bisect issue. So, you might want to reorder a bit. The patch itself looks good to me. Reviewed-by: Nicolin Chen