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Sun, 17 May 2026 13:16:02 -0700 From: Vishwaroop A To: , CC: , , , , , Subject: [PATCH v5 0/2] spi: add new_device/delete_device sysfs interface Date: Sun, 17 May 2026 20:16:00 +0000 Message-ID: <20260517201602.498135-1-va@nvidia.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SA2PEPF00003AEB:EE_|SA1PR12MB9247:EE_ X-MS-Office365-Filtering-Correlation-Id: 89097fed-721e-4e68-6f1b-08deb451218a X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700016|376014|82310400026|1800799024|30052699003|11063799003|13003099007|56012099003|18002099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.118.233;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc7edge2.nvidia.com;CAT:NONE;SFS:(13230040)(36860700016)(376014)(82310400026)(1800799024)(30052699003)(11063799003)(13003099007)(56012099003)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: aM4Az64cHmcctf6FBp+PVP9PydMkcjM3AemcXxnePwI7B8GhPpsb+6jQdKUvscsdIOvwofg7xGPbt0bjKKPfvR5vUzSLZok+EuEUV/6GXqZ11Nh/5QLaNwlHCbAa45whOeLj4Yr1mfiuKi/RLZ99wLZa7uEZRS/FosHXiuO8o8x3WkQ7YGeH2hnbvzOl2dYsqDVVHOS/3rCjcDuvskT2jyFwskRIkuFOcTs8v31wlPJ4OFKq48t2co3ouII9I2OYYUhMcXafEvoIbSzD95F+WMBrcN+Ju25fyRgqXL1bOiPdSTCe4lpbY33tM7jWfM1YVo00rrGhbovbDREFrCkwIMZFyAOtZZg/hHVmIs/VTjqH8WmeBNKilUOKHPXuNdasZzeZp0pXsTajiCa3gO3xGYvOun9y+9i/acNo8Gebhhs3vMNfhntIxr42N5bRodVH X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 May 2026 20:16:08.0512 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 89097fed-721e-4e68-6f1b-08deb451218a X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.118.233];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: SA2PEPF00003AEB.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB9247 Add I2C-style new_device/delete_device sysfs attributes to SPI host controllers, allowing userspace to instantiate and remove SPI devices at runtime without device-tree changes. Changes since v4: - Removed spi_unregister_device() call from new_device_store()'s ctlr->dead teardown path. That call raced with device_for_each_child(__unregister) in spi_unregister_controller(), causing a double-free. The extra get_device() ref keeps the struct alive; __unregister handles the actual cleanup. Changes since v3: - Replaced holding add_lock across __spi_add_device() + list insertion (which caused an ABBA deadlock between add_lock and the kernfs active reference during concurrent unbind) with: * A 'dead' flag on spi_controller, set in spi_unregister_controller() under both add_lock and userspace_clients_lock. * __spi_add_device() checks ctlr->dead under add_lock to reject new devices after teardown begins. * new_device_store() checks ctlr->dead under userspace_clients_lock before list insertion, falling back to cleanup + ENODEV. * add_lock is released before device_del() so in-flight sysfs stores can drain without deadlocking. * get_device() taken before spi_add_device() prevents use-after-free if __unregister runs concurrently. - Used #if IS_ENABLED() preprocessor guard (not runtime IS_ENABLED()) for the ctlr->dead check in __spi_add_device(), since the dead field is conditionally compiled. Changes since v2: - Gated sysfs attributes and locking on CONFIG_SPI_DYNAMIC. Changes since v1: - Added locking to prevent races between new_device_store() and concurrent spi_unregister_controller(). Link: https://lore.kernel.org/linux-tegra/909f0c92-d110-4253-903e-5c81e21e12c9@nvidia.com/ Vishwaroop A (2): spi: add new_device/delete_device sysfs interface docs: spi: add documentation for userspace device instantiation .../ABI/testing/sysfs-class-spi-master | 34 +++ Documentation/spi/index.rst | 1 + Documentation/spi/instantiating-devices.rst | 88 +++++++ drivers/spi/spi.c | 217 +++++++++++++++++- include/linux/spi/spi.h | 13 ++ 5 files changed, 347 insertions(+), 6 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-class-spi-master create mode 100644 Documentation/spi/instantiating-devices.rst -- 2.17.1