Commit 88109453 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Tejun Heo
Browse files

workqueue: use rcu_read_lock_sched() instead for accessing pwq in RCU 



rcu_read_lock_sched() is better than preempt_disable() if the code is
protected by RCU_SCHED.

Signed-off-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 951a078a

kernel/workqueue.c

+5 −5
Original line number Diff line number Diff line
@@ -3962,7 +3962,7 @@ bool workqueue_congested(int cpu, struct workqueue_struct *wq) 
	struct pool_workqueue *pwq;

	bool ret;



	preempt_disable();

	rcu_read_lock_sched();



	if (!(wq->flags & WQ_UNBOUND))

		pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
@@ -3970,7 +3970,7 @@ bool workqueue_congested(int cpu, struct workqueue_struct *wq) 
		pwq = first_pwq(wq);



	ret = !list_empty(&pwq->delayed_works);

	preempt_enable();

	rcu_read_unlock_sched();



	return ret;

}
@@ -4354,16 +4354,16 @@ bool freeze_workqueues_busy(void) 
		 * nr_active is monotonically decreasing.  It's safe

		 * to peek without lock.

		 */

		preempt_disable();

		rcu_read_lock_sched();

		for_each_pwq(pwq, wq) {

			WARN_ON_ONCE(pwq->nr_active < 0);

			if (pwq->nr_active) {

				busy = true;

				preempt_enable();

				rcu_read_unlock_sched();

				goto out_unlock;

			}

		}

		preempt_enable();

		rcu_read_unlock_sched();

	}

out_unlock:

	mutex_unlock(&wq_mutex);