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Tue, 29 Oct 2024 09:03:00 -0700 Date: Tue, 29 Oct 2024 09:02:58 -0700 From: Nicolin Chen To: Jason Gunthorpe CC: , , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v5 09/13] iommufd/selftest: Add refcount to mock_iommu_device Message-ID: References: <20241029153438.GH209124@nvidia.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20241029153438.GH209124@nvidia.com> X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL6PEPF0001AB55:EE_|MN0PR12MB5836:EE_ X-MS-Office365-Filtering-Correlation-Id: 5ac85655-8b1e-45d2-f70e-08dcf833388e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|1800799024|36860700013|82310400026; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?+UizP5ad71aOc3Ex5+H7I8lb4MuZiqouHVFjEf8OLK1GvUKh4zOJTZfWsdhJ?= =?us-ascii?Q?0t8u/nHKrRbt6u/rwCVf2qsrgoztQYfqjLd9F+INu/NLUGRlmS+/5VM7wBaf?= =?us-ascii?Q?xxL47hD3QlMJOUnb57bbGu7gwU4aHEkO09a2cFS8tyZG2eUlVmFYLK71QXTF?= =?us-ascii?Q?Da1ruScnElvPPWs9UIjDmTDl8acytSc6E9zvlVuMszUNA4uGtLx8Gn9MrW7c?= =?us-ascii?Q?qTGII/KdGWZY69PWxOKkQjW1qtuTT8q9dyAEn2SNPjye2SfKdwF516jIXEaY?= =?us-ascii?Q?Q3mDKAoTZ3jJ//PblkCbvze0HTajREF5h/cPwUJhuezzL9OWujF9ExABW0G9?= =?us-ascii?Q?lxxjaxd+W8WCYx5mgIVTlze8GP99t57lqRwneUNy6ozGUJfAZBtAOS2VO7cE?= =?us-ascii?Q?bjo3XCZgfLb3QgPYORrT1o3SJSFvx4EBH3cNxYS26veLKBjHdXvlxjLPALrs?= =?us-ascii?Q?AhmjccjX0AAMT77+JJc+cZmfZvXpE8puxhyO2kZ0gahT6rJB1Tjaia8I3GQM?= =?us-ascii?Q?FNJTGcEe7usJeJcT9icKXWkI36jHwIs0Kz/W/b0RNuMA8c3cBzjzUoXhk0Qb?= =?us-ascii?Q?itDPQVhZnYE+kt0aHGdHZ/iiTHM0cSAFwrWmBmgyt6AHS1Z48xIlUG0zrIGY?= =?us-ascii?Q?me7XpHdAm2wYOO2rlqKlToaaX4Iyo3vfRgBfojfX3CYWehDYPCn60InlISS2?= =?us-ascii?Q?o7q8ExLXt4Ijc4eCW5GlX4sPhfvROK4G+VXOuPnM+bWkTWoOrj4uBJEabUXi?= =?us-ascii?Q?M+Pv9lSYF39ESZjf/Zoygd0tQHbq1nwz9ZXRKVjX1i6vZlwPfD8x5SjLIgLw?= =?us-ascii?Q?1U3wcFHAIRmG0JK8qpRcO9Mf8b3jh7RAi61OHV5B9aCJzJXHX0IaFvSKY28F?= =?us-ascii?Q?1iTy6yqR/pQI299udkDpS4wvAIhvdJMB+PzEndM+xD/TnjZ9LaMPl2bp9AeD?= =?us-ascii?Q?gobokkMSmkDwPnsj3d02UukalFAeu13tHVPV3ilzkT4iUJ5xGyLg2FWkA3tQ?= =?us-ascii?Q?b1o18Q3/T8M9++WM2/5GdKaWSlGguy3EsQnuyyuEWE9xYo5twtQYhY96nSIW?= =?us-ascii?Q?AaSxra3sheKbNjX45PNvByXfjbjsWhWTGpuySoQDs5Xptjwdhyjdgg3O2v49?= =?us-ascii?Q?RDuHlWl52o9Hgav8jEMKTG/F1oAJnfXm+VtzH5Jr/zHp6gARsgBy1hX7qsTs?= =?us-ascii?Q?89i0QLG/l24D9AK0ojiiOFiASkGpH2buxPAz8oYz+pIVGIFxfsZXeXKB4Gh4?= =?us-ascii?Q?P7ENqy3LxwpLna9mRoUKGnRSn5P+GIjVqaJm8iJKDbUYeuQRqBzn0qK8aTwU?= =?us-ascii?Q?/lSaTSXNu2wY0XGmA3eWr0suTSXYfRar8j6n47NLvRA/NEKdAt9RADkR8KZw?= =?us-ascii?Q?wjf8FfX6lKgO8iGHcmb+uwIylJ1S/6hRiDV6p1TdX+MU09MSXA=3D=3D?= X-Forefront-Antispam-Report: CIP:216.228.117.161;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge2.nvidia.com;CAT:NONE;SFS:(13230040)(7416014)(376014)(1800799024)(36860700013)(82310400026);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Oct 2024 16:03:25.3963 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 5ac85655-8b1e-45d2-f70e-08dcf833388e 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: BL6PEPF0001AB55.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN0PR12MB5836 On Tue, Oct 29, 2024 at 12:34:38PM -0300, Jason Gunthorpe wrote: > On Fri, Oct 25, 2024 at 04:49:49PM -0700, Nicolin Chen wrote: > > For an iommu_dev that can unplug (so far only this selftest does so), the > > viommu->iommu_dev pointer has no guarantee of its life cycle after it is > > copied from the idev->dev->iommu->iommu_dev. > > > > Track the user count of the iommu_dev. Postpone the exit routine using a > > completion, if refcount is unbalanced. The refcount inc/dec will be added > > in the following patch. > > > > Signed-off-by: Nicolin Chen > > --- > > drivers/iommu/iommufd/selftest.c | 32 ++++++++++++++++++++++++-------- > > 1 file changed, 24 insertions(+), 8 deletions(-) > > Reviewed-by: Jason Gunthorpe > > Since this is built into the iommufd module it can't be unloaded > without also unloading iommufd, which is impossible as long as any > iommufd FDs are open. So I expect that the WARN_ON can never happen. Hmm, I assume we still need this patch then? Could a faulty "--force" possibly trigger it? Nicolin