FDC_KTHREAD_EXIT
while ((fdc->flags & FDC_KTHREAD_EXIT) == 0) {
fdc->flags &= ~(FDC_KTHREAD_EXIT | FDC_KTHREAD_ALIVE);
fdc->flags |= FDC_KTHREAD_EXIT;
(fdc->flags & FDC_KTHREAD_EXIT) == 0);