Commit c29eb853 authored by Tejun Heo's avatar Tejun Heo
Browse files

workqueue: more destroy_workqueue() fixes 



destroy_workqueue() warnings still, at a lower frequency, trigger
spuriously.  The problem seems to be in-flight operations which
haven't reached put_pwq() yet.

* Make sanity check grab all the related locks so that it's
  synchronized against operations which puts pwq at the end.

* Always print out the offending pwq.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: "Williams, Gerald S" <gerald.s.williams@intel.com>
parent 30ae2fc0

kernel/workqueue.c

+31 −14
Original line number Diff line number Diff line
@@ -355,6 +355,7 @@ EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq); 


static int worker_thread(void *__worker);

static void workqueue_sysfs_unregister(struct workqueue_struct *wq);

static void show_pwq(struct pool_workqueue *pwq);



#define CREATE_TRACE_POINTS

#include <trace/events/workqueue.h>
@@ -4314,6 +4315,22 @@ err_destroy: 
}

EXPORT_SYMBOL_GPL(alloc_workqueue);



static bool pwq_busy(struct pool_workqueue *pwq)

{

	int i;



	for (i = 0; i < WORK_NR_COLORS; i++)

		if (pwq->nr_in_flight[i])

			return true;



	if ((pwq != pwq->wq->dfl_pwq) && (pwq->refcnt > 1))

		return true;

	if (pwq->nr_active || !list_empty(&pwq->delayed_works))

		return true;



	return false;

}



/**

 * destroy_workqueue - safely terminate a workqueue

 * @wq: target workqueue
@@ -4348,28 +4365,28 @@ void destroy_workqueue(struct workqueue_struct *wq) 
		kfree(rescuer);

	}



	/* sanity checks */

	/*

	 * Sanity checks - grab all the locks so that we wait for all

	 * in-flight operations which may do put_pwq().

	 */

	mutex_lock(&wq_pool_mutex);

	mutex_lock(&wq->mutex);

	for_each_pwq(pwq, wq) {

		int i;



		for (i = 0; i < WORK_NR_COLORS; i++) {

			if (WARN_ON(pwq->nr_in_flight[i])) {

				mutex_unlock(&wq->mutex);

				show_workqueue_state();

				return;

			}

		}



		if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) ||

		    WARN_ON(pwq->nr_active) ||

		    WARN_ON(!list_empty(&pwq->delayed_works))) {

		spin_lock_irq(&pwq->pool->lock);

		if (WARN_ON(pwq_busy(pwq))) {

			pr_warning("%s: %s has the following busy pwq (refcnt=%d)\n",

				   __func__, wq->name, pwq->refcnt);

			show_pwq(pwq);

			spin_unlock_irq(&pwq->pool->lock);

			mutex_unlock(&wq->mutex);

			mutex_unlock(&wq_pool_mutex);

			show_workqueue_state();

			return;

		}

		spin_unlock_irq(&pwq->pool->lock);

	}

	mutex_unlock(&wq->mutex);

	mutex_unlock(&wq_pool_mutex);



	/*

	 * wq list is used to freeze wq, remove from list after

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