kthread Working

Hi, I have a douby regarding kthread working. How can we check that a kthread is working or exited. It may exit beacuse of call to do_exit in threadfn or callling kthread_stop function on task_struct (correct me if i am weong). I want to check that if kthread has finished its work or not. If not then what should I call so that kthread gets killed. If it is finshhed then which function I should call so that as to free kthread resources. Regards, Gaurav Mahajan.