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workqueue: more destroy_workqueue() fixes

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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: Tejun Heo <tj@kernel.org>
Cc: "Williams, Gerald S" <gerald.s.williams@intel.com>
This commit is contained in:
Tejun Heo 2019-09-23 11:08:58 -07:00
parent 30ae2fc0a7
commit c29eb85386
1 changed files with 31 additions and 14 deletions
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45
kernel/workqueue.c
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@ -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