[PATCH 5.4 095/132] kobject: Restore old behaviour of kobject_del(NULL)

[Greg Kroah-Hartman]

From: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

commit 40b8b826a6998639dd1c26f0e127f18371e1058d upstream.

The commit 079ad2fb4bf9 ("kobject: Avoid premature parent object freeing in
kobject_cleanup()") inadvertently dropped a possibility to call kobject_del()
with NULL pointer. Restore the old behaviour.

Fixes: 079ad2fb4bf9 ("kobject: Avoid premature parent object freeing in kobject_cleanup()")
Cc: stable <stable@xxxxxxxxxxxxxxx>
Reported-by: Qu Wenruo <quwenruo.btrfs@xxxxxxx>
Cc: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Reviewed-by: Qu Wenruo <wqu@xxxxxxxx>
Link: https://lore.kernel.org/r/20200803082706.65347-1-andriy.shevchenko@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 lib/kobject.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -630,8 +630,12 @@ static void __kobject_del(struct kobject
  */
 void kobject_del(struct kobject *kobj)
 {
-	struct kobject *parent = kobj->parent;
+	struct kobject *parent;
 
+	if (!kobj)
+		return;
+
+	parent = kobj->parent;
 	__kobject_del(kobj);
 	kobject_put(parent);
 }