Re: [PATCH 0/2] Synchronize DT overlay removal with devlink removals

Rob Herring
2023-12-06T17:15:55Z

On Thu, Nov 30, 2023 at 06:41:07PM +0100, Herve Codina wrote:
> Hi,

+Saravana for comment

Looks okay to me though.

>
> 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).
>
> Best regards,
> Hervé
>
> Herve Codina (2):
> driver core: Introduce device_link_wait_removal()
> of: overlay: Synchronize of_overlay_remove() with the devlink removals
>
> drivers/base/core.c | 26 +++++++++++++++++++++++---
> drivers/of/overlay.c | 6 ++++++
> include/linux/device.h | 1 +
> 3 files changed, 30 insertions(+), 3 deletions(-)
>
> --
> 2.42.0
>