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Received: from CH3PR12MB8659.namprd12.prod.outlook.com (2603:10b6:610:17c::13) by SJ1PR12MB6314.namprd12.prod.outlook.com (2603:10b6:a03:457::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8026.22; Mon, 7 Oct 2024 18:28:17 +0000 Received: from CH3PR12MB8659.namprd12.prod.outlook.com ([fe80::6eb6:7d37:7b4b:1732]) by CH3PR12MB8659.namprd12.prod.outlook.com ([fe80::6eb6:7d37:7b4b:1732%4]) with mapi id 15.20.8026.020; Mon, 7 Oct 2024 18:28:17 +0000 Date: Mon, 7 Oct 2024 15:28:16 -0300 From: Jason Gunthorpe To: Nicolin Chen Cc: kevin.tian@intel.com, will@kernel.org, joro@8bytes.org, suravee.suthikulpanit@amd.com, robin.murphy@arm.com, dwmw2@infradead.org, baolu.lu@linux.intel.com, shuah@kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kselftest@vger.kernel.org, eric.auger@redhat.com, jean-philippe@linaro.org, mdf@kernel.org, mshavit@google.com, shameerali.kolothum.thodi@huawei.com, smostafa@google.com, yi.l.liu@intel.com Subject: Re: [PATCH v2 10/19] iommufd/viommu: Add vdev_id helpers for IOMMU drivers Message-ID: <20241007182816.GD1365916@nvidia.com> References: <6ccdfb27c7aa5a5bb7e153165cf90114cae4687c.1724776335.git.nicolinc@nvidia.com> <20240905161415.GS1358970@nvidia.com> <20240911231103.GR58321@nvidia.com> <20241007153837.GT1365916@nvidia.com> <20241007171119.GY1365916@nvidia.com> Content-Type: text/plain; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?XRGpnLl2QCqjF1ZlZwejnMcRSesH6rqQ6HxEcMpUC18OPui34ICZdJ6Mpu73?= =?us-ascii?Q?g8sQl3bno/4KYW9LPVOdSKBwmhEFYAbqnJF2UnGJy2/d+SZPUhq5JSf+SDq2?= =?us-ascii?Q?ZiIkEO/XLx74XQmn6pYyyk230BBnq4T7UGPCkXbl0LlHSxmLWfNhq0h8DjU+?= =?us-ascii?Q?8gmDU/V3gaXPeCB1xeyCCHf5gGsP6hlytmBSEsgsYPEHeVdwIjBdoR3ufMBj?= =?us-ascii?Q?PbuaGOs+qWaWhRoq+TG7L5x5zl94WqPnopE8cRpQoR8ZM6TMgogC2V44SJYQ?= =?us-ascii?Q?ItGWz+Xc9X5ZsHoBM7u1vghf9/qs4YdAgrJAbZfGcEO/Jpkdyy57yJBtilGS?= =?us-ascii?Q?NjLaU+Xy7NlfAFPxujYKU6GKgP5fbQSweFaq2TO7MgST+VSidSp+ND3sctvh?= =?us-ascii?Q?4VSmw/MPMaaLQYBArijvACgere0QU5X/sWTop7/yN5dBzSQi9mc8xsnkxsWV?= =?us-ascii?Q?VAjnUHS+fvcxOkuh0Fi528T5zZrJHSRSL6KfbQnumHj0TDdRFFAdrrHmAsJN?= =?us-ascii?Q?CvuS6XNuXiPP/D9jQMAKEW5YJKWPOYwUqd4SMyoMBHvkfIIt2CZsjHRtue7L?= =?us-ascii?Q?vKIcOHQdThHs5aPGJQn+90JCOhpv02skKYBwtP0eOogPnJ9jL2M9Wglg3qG3?= =?us-ascii?Q?+gcqKMg5XVVhLnb0JYf8SYU4PmXuUGe3iGr+OrrtsGY7ey6QwO8fUPZcRgOH?= =?us-ascii?Q?dlqlMSxSQ8mjv/CgffsZPFgX+RHyosRjPmdL5WYdX+15MK8XP0gAoW0Yaek0?= =?us-ascii?Q?KsdjBwSb7nbNmnWCyhimTqzp5TJO/jiwtrh/0LilH8w5hK2ZWIJs10Xkd8wA?= =?us-ascii?Q?zdIBBHGNSIoKGP8NiI3Wm6daXGHPbv9tBJLollrAVfhnkbiN0KG55XumvMH+?= =?us-ascii?Q?AOb13uriffpTV916vfQq+9ik2VEcEGO3kA0gg6flc795YO0t7bEZx8E4q1sW?= =?us-ascii?Q?eRC86KVQkvc0D0yYbJwZnWVV7K7EMOR17Ety4osSd2QyGikto3gX4WBAD3ED?= =?us-ascii?Q?JPpG5uKSiBlhFiuDr6nFrHLQriRSwi5i2mhHysTyw2yzzlyF/x61fNlyXPLw?= =?us-ascii?Q?OUgMiJ8CnI8D3Y9QA8QSZ7IJvoiz2qtHAQFHunYTKDSPrZV5JDZNzkvWbraQ?= =?us-ascii?Q?JqY85MUeweV6T+MnudUWO5eNJ+fAJH/4MTHB1DiER2keq9BC6qkX0ePq5S7B?= =?us-ascii?Q?v3U3YepZHQxQK9REHfFLk2KrYhBD7t/iidzmoLQpwC7u46g+NQ3Dw7f2xsHh?= =?us-ascii?Q?wKgJdu3f+/CuFu8tCQsabyzHssxRIsb5icAZmptjNl4tfvZjliVmW4Qvws3R?= =?us-ascii?Q?9F/yc+n97ZyVJO4GZovqfTXnrDfLJDQnIf9RC8h5xVawQOp+iLyQqlwmYG7+?= =?us-ascii?Q?VX+7Mjr/a4u+U/lFFuCla98doOrCR9NBoBDhUtPhMMXz3EV2XyfHQBP6ktk8?= =?us-ascii?Q?5pthnjejU4qHZUKYs2SD3Og3/coZEMzjX9nkIJSgS199BCLrSpD6sYDeF4KR?= =?us-ascii?Q?TR2akGKkP8E9449LMT4W48AOVmpNeXdyUCXz8az+x+Bjkca2nCLGk76U/URz?= =?us-ascii?Q?ClHNCcFZ6UdcyQPJe9k=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8419f830-44c5-4dad-2e00-08dce6fdd052 X-MS-Exchange-CrossTenant-AuthSource: CH3PR12MB8659.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Oct 2024 18:28:17.7533 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: IKbB7M/llpG8nggQjyUtMZfuQ1oEqrTFGshnjbnHpVDOes4eVGlvXkn5Ahroe1Qg X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ1PR12MB6314 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241007_112824_533548_04D84515 X-CRM114-Status: GOOD ( 10.08 ) 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 Mon, Oct 07, 2024 at 10:25:01AM -0700, Nicolin Chen wrote: > This is for vdev/dev v.s. hwpt. We need the lock for viommu's > vdev xarray. > > Yet, giving a 2nd thought, I feel the lock would be useless if > a driver tries to refer the returned vdev (with this helper) > after the vdev object is destroyed.. > > We could only note something similar that caller must be aware > of the life cycle of vdev itself.. Yes, I imagined you'd use the xa_lock for this an it solves both problems at once. Jason