diff mbox series

[02/12] software node: Increment parent node's ref count

Message ID 20190315165800.5058-3-heikki.krogerus@linux.intel.com (mailing list archive)
State Deferred, archived
Delegated to: Andy Shevchenko
Headers show
Series platform/x86: intel_cht_int33fe: Real DisplayPort reference | expand

Commit Message

Heikki Krogerus March 15, 2019, 4:57 p.m. UTC 
If the parent node is removed before its children, release()
may be called first for the parent instead of the last child
when the child's ref count reaches zero. Since the nodes
release their parent's resources in the release callback,
that would cause NULL pointer dereference to happen. To
prevent that from ever happening, incrementing the parent
node's reference count when creating a new child node and
decrementing it when the child node is "released".

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
---
 drivers/base/swnode.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
index 3a50a8edd3d3..8d4485d8d0f8 100644
--- a/drivers/base/swnode.c
+++ b/drivers/base/swnode.c
@@ -560,6 +560,7 @@  static void software_node_release(struct kobject *kobj)
 	if (swnode->parent) {
 		ida_simple_remove(&swnode->parent->child_ids, swnode->id);
 		list_del(&swnode->entry);
+		kobject_put(&swnode->parent->kobj);
 	} else {
 		ida_simple_remove(&swnode_root_ids, swnode->id);
 	}
@@ -610,8 +611,10 @@  fwnode_create_software_node(const struct property_entry *properties,
 	INIT_LIST_HEAD(&swnode->children);
 	swnode->parent = p;
 
-	if (p)
+	if (p) {
+		kobject_get(&p->kobj);
 		list_add_tail(&swnode->entry, &p->children);
+	}
 
 	ret = kobject_init_and_add(&swnode->kobj, &software_node_type,
 				   p ? &p->kobj : NULL, "node%d", swnode->id);