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Commit f7142ed4 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Tejun Heo
Browse files

workqueue: simplify wq_update_unbound_numa() 



wq_update_unbound_numa() is known be called with wq_pool_mutex held.

But wq_update_unbound_numa() requests wq->mutex before reading
wq->unbound_attrs, wq->numa_pwq_tbl[] and wq->dfl_pwq.  But these fields
were changed to be allowed being read with wq_pool_mutex held.  So we
simply remove the mutex_lock(&wq->mutex).

Without the dependence on the the mutex_lock(&wq->mutex), the test
of wq->unbound_attrs->no_numa can also be moved upward.

The old code need a long comment to describe the stableness of
@wq->unbound_attrs which is also guaranteed by wq_pool_mutex now,
so we don't need this such comment.

Signed-off-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 5b95e1af

kernel/workqueue.c

+5 −15
Original line number Diff line number Diff line
@@ -3708,7 +3708,8 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu, 


	lockdep_assert_held(&wq_pool_mutex);



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

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

	    wq->unbound_attrs->no_numa)

		return;



	/*
@@ -3719,10 +3720,6 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu, 
	target_attrs = wq_update_unbound_numa_attrs_buf;

	cpumask = target_attrs->cpumask;



	mutex_lock(&wq->mutex);

	if (wq->unbound_attrs->no_numa)

		goto out_unlock;



	copy_workqueue_attrs(target_attrs, wq->unbound_attrs);

	pwq = unbound_pwq_by_node(wq, node);
@@ -3734,33 +3731,26 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu, 
	 */

	if (wq_calc_node_cpumask(wq->dfl_pwq->pool->attrs, node, cpu_off, cpumask)) {

		if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask))

			goto out_unlock;

			return;

	} else {

		goto use_dfl_pwq;

	}



	mutex_unlock(&wq->mutex);



	/* create a new pwq */

	pwq = alloc_unbound_pwq(wq, target_attrs);

	if (!pwq) {

		pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",

			wq->name);

		mutex_lock(&wq->mutex);

		goto use_dfl_pwq;

	}



	/*

	 * Install the new pwq.  As this function is called only from CPU

	 * hotplug callbacks and applying a new attrs is wrapped with

	 * get/put_online_cpus(), @wq->unbound_attrs couldn't have changed

	 * inbetween.

	 */

	/* Install the new pwq. */

	mutex_lock(&wq->mutex);

	old_pwq = numa_pwq_tbl_install(wq, node, pwq);

	goto out_unlock;



use_dfl_pwq:

	mutex_lock(&wq->mutex);

	spin_lock_irq(&wq->dfl_pwq->pool->lock);

	get_pwq(wq->dfl_pwq);

	spin_unlock_irq(&wq->dfl_pwq->pool->lock);