Commit 7a50f766 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched: Simplify yield_to() 



Use guards to reduce gotos and simplify control flow.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 92c2ec5b

kernel/sched/core.c

+29 −38
Original line number Diff line number Diff line
@@ -8888,10 +8888,9 @@ int __sched yield_to(struct task_struct *p, bool preempt) 
{

	struct task_struct *curr = current;

	struct rq *rq, *p_rq;

	unsigned long flags;

	int yielded = 0;



	local_irq_save(flags);

	scoped_guard (irqsave) {

		rq = this_rq();



again:
@@ -8900,43 +8899,35 @@ int __sched yield_to(struct task_struct *p, bool preempt) 
		 * If we're the only runnable task on the rq and target rq also

		 * has only one task, there's absolutely no point in yielding.

		 */

	if (rq->nr_running == 1 && p_rq->nr_running == 1) {

		yielded = -ESRCH;

		goto out_irq;

	}

		if (rq->nr_running == 1 && p_rq->nr_running == 1)

			return -ESRCH;



	double_rq_lock(rq, p_rq);

	if (task_rq(p) != p_rq) {

		double_rq_unlock(rq, p_rq);

		guard(double_rq_lock)(rq, p_rq);

		if (task_rq(p) != p_rq)

			goto again;

	}



		if (!curr->sched_class->yield_to_task)

		goto out_unlock;

			return 0;



		if (curr->sched_class != p->sched_class)

		goto out_unlock;

			return 0;



		if (task_on_cpu(p_rq, p) || !task_is_running(p))

		goto out_unlock;

			return 0;



		yielded = curr->sched_class->yield_to_task(rq, p);

		if (yielded) {

			schedstat_inc(rq->yld_count);

			/*

		 * Make p's CPU reschedule; pick_next_entity takes care of

		 * fairness.

			 * Make p's CPU reschedule; pick_next_entity

			 * takes care of fairness.

			 */

			if (preempt && rq != p_rq)

				resched_curr(p_rq);

		}

	}



out_unlock:

	double_rq_unlock(rq, p_rq);

out_irq:

	local_irq_restore(flags);



	if (yielded > 0)

	if (yielded)

		schedule();



	return yielded;