[PATCH v2 2/2] of: dynamic: flush devlinks workqueue before destroying the changeset

Nuno Sa via B4 Relay
2024-02-05T12:09:34Z

From: Nuno Sa <nuno.sa@analog.com>

Device links will drop their supplier + consumer refcounts
asynchronously. That means that the refcount of the of_node attached to
these devices will also be dropped asynchronously and so we cannot
guarantee the DT overlay assumption that the of_node refcount must be 1 in
__of_changeset_entry_destroy().

Given the above, call the new fwnode_links_flush_queue() helper to flush
the devlink workqueue so we can be sure that all links are dropped before
doing the proper checks.

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
drivers/of/dynamic.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
index 3bf27052832f..b7153c72c9c9 100644
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -14,6 +14,7 @@
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/proc_fs.h>
+#include <linux/fwnode.h>

#include "of_private.h"

@@ -518,6 +519,13 @@ EXPORT_SYMBOL(of_changeset_create_node);

static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)
{
+ /*
+ * device links drop their device references (and hence their of_node
+ * references) asynchronously on a dedicated workqueue. Hence we need
+ * to flush it to make sure everything is done before doing the below
+ * checks.
+ */
+ fwnode_links_flush_queue();
if (ce->action == OF_RECONFIG_ATTACH_NODE &&
of_node_check_flag(ce->np, OF_OVERLAY)) {
if (kref_read(&ce->np->kobj.kref) > 1) {

--
2.43.0