In the following sequence: 1) of_platform_depopulate() 2) of_overlay_remove()
During the step 1, devices are destroyed and devlinks are removed. During the step 2, OF nodes are destroyed but __of_changeset_entry_destroy() can raise warnings related to missing of_node_put(): ERROR: memory leak, expected refcount 1 instead of 2 ...
Indeed, during the devlink removals performed at step 1, the removal itself releasing the device (and the attached of_node) is done by a job queued in a workqueue and so, it is done asynchronously with respect to function calls. When the warning is present, of_node_put() will be called but wrongly too late from the workqueue job.
In order to be sure that any ongoing devlink removals are done before the of_node destruction, synchronize the of_changeset_destroy() with the devlink removals.
Fixes: 80dd33cf72d1 ("drivers: base: Fix device link removal") Cc: stable@vger.kernel.org Signed-off-by: Herve Codina herve.codina@bootlin.com Reviewed-by: Saravana Kannan saravanak@google.com Tested-by: Luca Ceresoli luca.ceresoli@bootlin.com Reviewed-by: Nuno Sa nuno.sa@analog.com --- drivers/of/dynamic.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c index 3bf27052832f..4d57a4e34105 100644 --- a/drivers/of/dynamic.c +++ b/drivers/of/dynamic.c @@ -9,6 +9,7 @@
#define pr_fmt(fmt) "OF: " fmt
+#include <linux/device.h> #include <linux/of.h> #include <linux/spinlock.h> #include <linux/slab.h> @@ -667,6 +668,17 @@ void of_changeset_destroy(struct of_changeset *ocs) { struct of_changeset_entry *ce, *cen;
+ /* + * When a device is deleted, the device links to/from it are also queued + * for deletion. Until these device links are freed, the devices + * themselves aren't freed. If the device being deleted is due to an + * overlay change, this device might be holding a reference to a device + * node that will be freed. So, wait until all already pending device + * links are deleted before freeing a device node. This ensures we don't + * free any device node that has a non-zero reference count. + */ + device_link_wait_removal(); + list_for_each_entry_safe_reverse(ce, cen, &ocs->entries, node) __of_changeset_entry_destroy(ce); }