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Herne" , Alex Williamson , Liu Yi L , Halil Pasic , kvm@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH v1 03/18] vfio/ccw: Ensure mdev->dev is cleared on mdev remove Message-ID: <20220603133713.GZ1343366@nvidia.com> References: <20220602171948.2790690-1-farman@linux.ibm.com> <20220602171948.2790690-4-farman@linux.ibm.com> <65153af9-be41-8f20-98f1-bc047518c3ae@linux.ibm.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <65153af9-be41-8f20-98f1-bc047518c3ae@linux.ibm.com> X-ClientProxiedBy: BL1PR13CA0273.namprd13.prod.outlook.com (2603:10b6:208:2bc::8) To MN2PR12MB4192.namprd12.prod.outlook.com (2603:10b6:208:1d5::15) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: efb86d95-a36e-4457-0c67-08da45662b1d X-MS-TrafficTypeDiagnostic: MN2PR12MB4799:EE_ X-Microsoft-Antispam-PRVS: X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:MN2PR12MB4192.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230001)(4636009)(366004)(6486002)(53546011)(186003)(6916009)(508600001)(2906002)(54906003)(33656002)(4326008)(8676002)(66556008)(8936002)(66476007)(66946007)(5660300002)(6512007)(1076003)(2616005)(26005)(86362001)(6506007)(316002)(38100700002)(36756003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?xYYcfwouiecDrwF88JXJBwpkvEO6pMLgB6bAuguk0QYZmf+mSK6YJqV/A6R3?= =?us-ascii?Q?PGxzRDEq22byb/J3Sgdx3YNiJsw1uoaznlQEYluyOelVP20Ba/U1mOOollx2?= =?us-ascii?Q?6ezdBWq6DBhS8/SxpuD/6Z8Zzo2sh3TEl/MxfQmIwF3Vscfiwwvji47yl0Js?= =?us-ascii?Q?z0M71FgcI4QdmGZ1y9iNaSZf1Cw7GdPwVqmloFDC1lBHF0j+KBfXifu1Fv/G?= =?us-ascii?Q?Qm1ugrU5imXoQKGQwbuCDJjiGjtA0w49rPdacR1btilE7UiZIe39XIJksHaf?= =?us-ascii?Q?6mAffZuU/HpnZeEQNJUYlaYR8MZBERgkTcgEJ0L36enYuucohIZeXT2hrRMA?= =?us-ascii?Q?z5m5/q1munGlrhNaSJUfNXAVf4djbsa71UQ7/pePpl56RIP3/um3hb+xgy1M?= =?us-ascii?Q?QdlI3uZHdoKdkv07NosUlvrKPxBoQ1AyAaZ8gLp3bW2MTPj2dumUgBQCeyRb?= =?us-ascii?Q?WtSo9sHVPXNbHObLpmphRQ7ny5KdDmEX6OJMbB7m55gkp0l9qe+YKWq4qFPS?= =?us-ascii?Q?ZirDZPsznJBDnUHOVJssl+Y+IKtB4oEEa94SfsaqeGQ6MhOfF7PvNV1OXIr+?= =?us-ascii?Q?1URatzqjIXFrHtHOApz9T0k9LA8/Mmkl66toLrTBv7lwCX712LahHbw1E2Z4?= =?us-ascii?Q?jXBV3oX4FHbxAc0PUNat4dZf1X1Q5r4DR9EIOWvJInNcQQXbYlU/CrzVSyiv?= =?us-ascii?Q?LknDtPeFDoTZeQ+nETb1L81FCBpnFD9R7F29vgnnB8mRF1AoXSpbapPRpoVe?= =?us-ascii?Q?2u6x6Awq+WWXzkcqgxN52XrfwRW49Dw8HhjMUwRiD8gF76O0iVdjGtddho+Q?= =?us-ascii?Q?tqRT+JlIqZ/DD1HZVVcMhnHHl77TDXL5rlfXm3HYlipVVYTYQQPqASShb7KA?= =?us-ascii?Q?FKXXg5iYeVHQ1tLdUWMG0LrlBFv+uNL2FPlpMyEYUzj5JXhEHOsED6maXUOD?= =?us-ascii?Q?SZeH9yyieNTVjiitKzRu8202ucdB9xGCBvGJU/E3DaNnquQDi6XR/uYCXj4k?= =?us-ascii?Q?XZw4+raG+amtd5UN7wZGnIFyy0I8OXeuMVmIwkLytLSN1dKmXbjL2MWZa4Rw?= =?us-ascii?Q?d+QBAr/VV1g1WkGI7j++sSQ2Ny/7w8bghPbVsRgJgx5jPVCi60oylDWaNviX?= =?us-ascii?Q?GBmOtvOc9DiE6oepgjMoLrEqn14e19+wCTgy3A0B/xAGv08ETuAb4ohTBTlW?= =?us-ascii?Q?Ot9xQpMAs5x1I7vPw8Fv9sBkRk55YWfG1INCqt76m9ng/GAIvv40LIiMVm15?= =?us-ascii?Q?GCeAYX+RmejhsJWgxCiUCHVF34S1VCZRpsBUT8y0ufGIeNOLfcinWlJ4FPK0?= =?us-ascii?Q?OXBNtjVYvyLgtdAr4fdu7TdL1sJ6raF7/JcAQpr8eaeO7USmZcljwTBGfg5p?= =?us-ascii?Q?FJIDjq/mtc/bD9UO7dNJRPkbpXrmygw9H/61PgxqC1QNMDELf1q1rl5CIY+z?= =?us-ascii?Q?pf7MjldwkzzfH8KILk+WU/XPYztaa7GAvHvPAwHPR7Jxc7JYYJLXVNb0cobV?= =?us-ascii?Q?enkgmLscG6SCsKIojYYAy38n0SK+y5WIlLiAXUGLu+OxjC2j7zv/WzDrTvlm?= =?us-ascii?Q?L/cASOT2x4BQhF5SD4rRybfUqfeCxWBsowLtKvIjhNAM+RFvgbDHYCxSpQew?= =?us-ascii?Q?1hprORno01SQTgozA/thHyE7sAshe6JovLPATz2efYy2y0YnVgAqG8Xgklhn?= =?us-ascii?Q?f6ai8uNJXxUMN9gXD4rCs6V2knSyqlU13cFnD7OEsON4wjao49s7C+qtLu8F?= =?us-ascii?Q?4aZPhtpnQg=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: efb86d95-a36e-4457-0c67-08da45662b1d X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB4192.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Jun 2022 13:37:13.9901 (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: Bf4OraLZDj734eOoM1koUOji2j9Y5f+PDTquGUhH86GvFiyJw7UE/wZ2iIhr6vma X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4799 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Fri, Jun 03, 2022 at 09:25:19AM -0400, Matthew Rosato wrote: > On 6/2/22 1:19 PM, Eric Farman wrote: > > The mdev is linked with the vfio_ccw_private pointer when the mdev > > is probed, but it's not cleared once the mdev is removed. > > > > This isn't much of a concern based on the current device lifecycle, > > but fix it so that things make sense in later shuffling. > > > > Fixes: 3bf1311f351ef ("vfio/ccw: Convert to use vfio_register_emulated_iommu_dev()") > > Signed-off-by: Eric Farman > > drivers/s390/cio/vfio_ccw_ops.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c > > index a403d059a4e6..a0a3200b0b04 100644 > > +++ b/drivers/s390/cio/vfio_ccw_ops.c > > @@ -159,6 +159,7 @@ static void vfio_ccw_mdev_remove(struct mdev_device *mdev) > > private->sch->schid.ssid, > > private->sch->schid.sch_no); > > + dev_set_drvdata(&mdev->dev, NULL); > > vfio_unregister_group_dev(&private->vdev); > > if ((private->state != VFIO_CCW_STATE_NOT_OPER) && > > Seems harmless enough. > > Reviewed-by: Matthew Rosato > > But is this just precautionary or is it fixing a real problem (if the former > I don't think a fixes tag makes sense) > > I also ask because I note vfio-ap clears its driver_data in mdev_remove but > also leaves the pointer set, meaning they might need a similar cleanup and > should probably have a look (CC Tony & Jason H) There should be no reason to clear the drvdata on remove - the driver must be designed to guarentee all references to the dev stop before the remove function returns. Jason