Why check (&cwq->worklist) not check (&cwq->more_work)?

In Linux Kernel Development 3rd edition.Chapter 8, 8.4.1.2

for (;;) {         prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE);         if (list_empty(&cwq->worklist))              schedule();         finish_wait(&cwq->more_work, &wait);         run_workqueue(cwq);}

We can see prepare_to_wait() will add &wait into 'more_work' ( wait_queue_head_t )but the next line

if (list_empty(&cwq->worklist))

why list_empty check &cwq->workllist, not the 'morework' just processed?

I didn't see &cwq->worklist has any update here.