Hi, In the following sequence: of_platform_depopulate(); /* Remove devices from a DT overlay node */ of_overlay_remove(); /* Remove the DT overlay node itself */ Some warnings are raised by __of_changeset_entry_destroy() which was called from of_overlay_remove(): ERROR: memory leak, expected refcount 1 instead of 2 ... The issue is that, during the device devlink removals triggered from the of_platform_depopulate(), jobs are put in a workqueue. These jobs drop the reference to the devices. When a device is no more referenced (refcount == 0), it is released and the reference to its of_node is dropped by a call to of_node_put(). These operations are fully correct except that, because of the workqueue, they are done asynchronously with respect to function calls. In the sequence provided, the jobs are run too late, after the call to __of_changeset_entry_destroy() and so a missing of_node_put() call is detected by __of_changeset_entry_destroy(). This series fixes this issue introducing device_link_wait_removal() in order to wait for the end of jobs execution (patch 1) and using this function to synchronize the overlay removal with the end of jobs execution (patch 2). Compared to the previous iteration: https://lore.kernel.org/linux-kernel/20240229105204.720717-1-herve.codina@xxxxxxxxxxx/ this v4 series: - Uses flush_workqueue() - Keep the of_mutex lock taken calling device_link_wait_removal() - Perform the wait in of_changeset_destroy() This series handles cases reported by Luca [1] and Nuno [2]. [1]: https://lore.kernel.org/all/20231220181627.341e8789@booty/ [2]: https://lore.kernel.org/all/20240205-fix-device-links-overlays-v2-2-5344f8c79d57@xxxxxxxxxx/ Best regards, Hervé Changes v3 -> v4 - Patch 1 Uses flush_workqueue() instead of drain_workqueue(). - Patch 2 Remove unlock/re-lock when calling device_link_wait_removal() Move device_link_wait_removal() call to of_changeset_destroy() Update commit log Changes v2 -> v3 - Patch 1 No changes - Patch 2 Add missing device.h Changes v1 -> v2 - Patch 1 Rename the workqueue to 'device_link_wq' Add 'Fixes' tag and Cc stable - Patch 2 Add device.h inclusion. Call device_link_wait_removal() later in the overlay removal sequence (i.e. in free_overlay_changeset() function). Drop of_mutex lock while calling device_link_wait_removal(). Add 'Fixes' tag and Cc stable Herve Codina (2): driver core: Introduce device_link_wait_removal() of: dynamic: Synchronize of_changeset_destroy() with the devlink removals drivers/base/core.c | 26 +++++++++++++++++++++++--- drivers/of/dynamic.c | 7 +++++++ include/linux/device.h | 1 + 3 files changed, 31 insertions(+), 3 deletions(-) -- 2.43.0
