prepare_to_wait
prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
prepare_to_wait(&guc->ct.wq, &wait, state);
prepare_to_wait(&ddat->waitq, &wait, TASK_INTERRUPTIBLE);
prepare_to_wait(&wqh, &__wq_entry, prio); \
prepare_to_wait(&wqh, &__wq_entry, prio); \
prepare_to_wait(&wqh, &__wq_entry, 0); \
void prepare_to_wait(wait_queue_head_t *, wait_queue_entry_t *, int);