- __acquires(rq->lock)
-{
- struct rq *rq;
-
- for (;;) {
- raw_spin_lock_irqsave(&p->pi_lock, *flags);
- rq = task_rq(p);
- raw_spin_lock(&rq->lock);
- /*
- * move_queued_task() task_rq_lock()
- *
- * ACQUIRE (rq->lock)
- * [S] ->on_rq = MIGRATING [L] rq = task_rq()
- * WMB (__set_task_cpu()) ACQUIRE (rq->lock);
- * [S] ->cpu = new_cpu [L] task_rq()
- * [L] ->on_rq
- * RELEASE (rq->lock)
- *
- * If we observe the old cpu in task_rq_lock, the acquire of
- * the old rq->lock will fully serialize against the stores.
- *
- * If we observe the new cpu in task_rq_lock, the acquire will
- * pair with the WMB to ensure we must then also see migrating.
- */
- if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
- lockdep_pin_lock(&rq->lock);
- return rq;
- }
- raw_spin_unlock(&rq->lock);
- raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
-
- while (unlikely(task_on_rq_migrating(p)))
- cpu_relax();
- }
-}