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McKenney" , Herve Codina , Jia Jia , linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 2/6] gpiolib: free the label of lines released after their chip was removed Date: Fri, 16 Oct 2026 10:46:50 +0300 Message-ID: <20261016074704.1860749-3-aambrozewicz@nvidia.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: <20261012-gpiolib-chip-removal-v1-0-aambrozewicz@nvidia.com> <20261012-gpiolib-chip-removal-v1-2-aambrozewicz@nvidia.com> Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: TL0P290CA0010.ISRP290.PROD.OUTLOOK.COM (2603:1096:950:5::14) To PH7PR12MB5974.namprd12.prod.outlook.com (2603:10b6:510:1d9::19) 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: PH7PR12MB5974:EE_|MN2PR12MB4320:EE_ X-MS-Office365-Filtering-Correlation-Id: f131370d-6822-4092-4df2-08df2b59b812 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|23010399003|376014|1800799024|366016|10067099003|22082099003|18002099003|11063799006|4143699003|56012099006; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?o4mKvPAFEQzoHjq6RD5gsDKL9xf1tJgikM9d7zX3ZMd8m4yMSFmeGHKuk5Ht?= =?us-ascii?Q?wkya/Ggs1iYAUO9na5ZzbJOQ3Ic/squnkdr3nS7ykIyqkTwcIMiq8K0gsc7/?= =?us-ascii?Q?onQBm6ZLnAkqjvN3XJAUnZ656q7CRKiibQ4nEofY1VG2m5q3/JT1Xkxlr092?= =?us-ascii?Q?SJmAJca9NCZ6H482qg/uys+4rScxJt6w5ewFz1tY5V7piZFjgzgA81gsknMt?= =?us-ascii?Q?Qfv+Icr+WLdFujLXkPNicm7EoKq2/hPr96kzH+hD3oO1bt5uLwc2NCq84Ts6?= =?us-ascii?Q?KCS6vdFRbGmhtoxn/jSmVtDPN1tLHoNHbo99a0m1USxyM9ipPqCrhtb3m/Ti?= =?us-ascii?Q?xLEIrGRIkEdgshNX1Y1d0qu+b69UF9NN73BdXB4D6NTxDIHteO6Y9UZsQ03u?= =?us-ascii?Q?X3b9dQFPEeoDPaJXPrtmflIPK+i3f8f3KW2DHPS25mG1B6lb+/mgckI49ZT6?= =?us-ascii?Q?8suR7efPmKMUWPW5sq+dFJTrAAd5vpfpSc4gZoS7loBT7cbrsPdP0UwDSrkF?= =?us-ascii?Q?6AfS08In43SGfD0DPnfU1wo6HuBe+T3pyHlUZKRZW4oR5WTACJmqwW9hAY8n?= =?us-ascii?Q?dfcfEZYkC8osY1oRki1TcQ5eupcvv2HDlUlIVApGQ5Hxk8D/I0zMxSEyvZzN?= =?us-ascii?Q?lk+T3sZ/uLDwiC09HHJnDjorMLU/5BzsP8ANIAv6cUIbk9yFLd2QPhhgIYml?= =?us-ascii?Q?bPuh0vrsJ0uTzVikFAVSwIYjKi4ieYceJOjJd0p9AcW7vg5UuCl7QN24A1vv?= =?us-ascii?Q?ZFRXWpYirnUPVC92TOnyUrGNvMSp4p6XALAhFxYck/apcJ5OF6Fq296PXl2Z?= =?us-ascii?Q?erGgcKtW+5HMEyWg9wF8nBNSeHhlN6PXK34qjPMsz8hUJUIlv2aus8ogT3ae?= =?us-ascii?Q?VlPEIPy7rrObFWWhmv4g6uvQsJD9uet3RKYBHAyavt9dKfnb0QW2f5A9Ukrn?= =?us-ascii?Q?Fr2RCLrnAUS8jC4Z3+DrKM2Q+oT4PobkSiAdcJz8lBW2JW/9JZN1ywpZg2JZ?= =?us-ascii?Q?Za+NGMVEBOnVOCE6HXHTAFLYIHvNCfeiXoPshF/elJe7hZsPYEJmIkjeiLcJ?= =?us-ascii?Q?x5tX7xYTkivp21YmMAMqEM5Yn+5w5wmoIRJR0PDzN+1qZtjehZ1KlanyT9Cw?= =?us-ascii?Q?DfXtg/jBmnnbmEXzWNPAcBo7JeeIgfXDOA4oxd0bZgePF47srurW5U+44Jfg?= =?us-ascii?Q?8nMwDDtlZt7TMN1ic7hiP4xJOjh0HZLEheHfsUkvR9EyK1dy5vka5vH1WqLb?= =?us-ascii?Q?s5LXnFp/8rqPJMk2zgoS58lbqVbnz3TL+vkstt51vWZyQSCXsavy6yrkG1kQ?= =?us-ascii?Q?737sB618PF2wZehW0HKw7U/Z2wRUq2BRqsiyX2jOlAWA0FYnWP+HdG7FHkPe?= =?us-ascii?Q?CizEOq6ne6XRoB4d558nTgl4hyGw1BGw3qb0g+lfdKgH1CnWPB5Ssdc7Wq5Q?= =?us-ascii?Q?uJE12gY0ZRk2UJ4bLP2xvfJw5zh4AZRxcgiSFpL16uMJ4XiwI8ZR1xr8fyI0?= =?us-ascii?Q?VsOGpocyiJy5nIfjTZfPTxibIpw3WMsTd7FX9VZB3+XCKVJ8021zpBvkSA8t?= =?us-ascii?Q?nDLNivTYOTKGrXyva2aPbcsCKbVL4H5q75aQpSISTeqDN40gI3SR7VXzw95p?= =?us-ascii?Q?r/HKH2+jZ0j5brAfmj8E2ZXhnZvOWFVrH5oE0wbt4Q6FmsgvDBDxDGi+emvA?= =?us-ascii?Q?6jVwnRNV0eaJpxj7tfeF6itL6Gz1P0lZNmgbLyFrdXa7UCBpn/QZlbvEg2uD?= =?us-ascii?Q?qOWXvmef8w=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: f131370d-6822-4092-4df2-08df2b59b812 X-MS-Exchange-CrossTenant-AuthSource: PH7PR12MB5974.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Oct 2026 07:47:25.3203 (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: LUd5PzvstaE4vrtey7/lVPleOzsrdE+F3TkT7iW1Ppwgn5ifaOm1dQCN3c/UUZc1HvFOJeoW3nafSFxX39ctSA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4320 On Tue, Oct 13, 2026 at 06:38:38PM +0300, Andy Shevchenko wrote: > I have two questions here. > > 1/ Do we still need to notify user space in the case of the chip gone? No. The notification goes to the chip's character device files that watch the line, and once the chip is gone read() on them returns -ENODEV, so the event could not be delivered. It is not sent in that case today either, and the patch keeps it that way. > 2/ Can we write the above as > > if (guard.gc && !test_bit(GPIOD_FLAG_REQUESTED, &flags)) > return; > > desc_set_label(desc, NULL); > > if (guard_gc) { > ...current code... > } Yes, v2 will look like that. The label is then cleared before ->free() rather than after it. A requested line already shows no label for a moment today, between desc_set_label() and the flags update, so I don't think that matters, but say if you would rather keep the order. Adrian