workqueue: protect wq->saved_max_active with wq->mutex

We're expanding wq->mutex to cover all fields specific to each workqueue with the end goal of replacing pwq_lock which will make locking simpler and easier to understand. This patch makes wq->saved_max_active protected by wq->mutex instead of pwq_lock. As pwq_lock locking around pwq_adjust_mac_active() is no longer necessary, this patch also replaces pwq_lock lockings of for_each_pwq() around pwq_adjust_max_active() to wq->mutex. tj: Rebased on top of the current dev branch. Updated description.

Lai Jiangshan committed 13 years ago

Commit a357fc01 parent b09f4fd1 file · +16 −17Browse files

Showing the changes to kernel/workqueue.c (1 of 1 file). Show all

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kernel/workqueue.c+16−17

 	struct worker		*rescuer;	/* I: rescue worker */
 	int			nr_drainers;	/* WQ: drain in progress */
-	int			saved_max_active; /* PW: saved pwq max_active */
+	int			saved_max_active; /* WQ: saved pwq max_active */
 #ifdef CONFIG_SYSFS
 	struct wq_device	*wq_dev;	/* I: for sysfs interface */
 	bool freezable = wq->flags & WQ_FREEZABLE;
 	/* for @wq->saved_max_active */
-	lockdep_assert_held(&pwq_lock);
+	lockdep_assert_held(&wq->mutex);
 	/* fast exit for non-freezable wqs */
 	if (!freezable && pwq->max_active == wq->saved_max_active)
 		return;
-	spin_lock(&pwq->pool->lock);
+	spin_lock_irq(&pwq->pool->lock);
 	if (!freezable || !(pwq->pool->flags & POOL_FREEZING)) {
 		pwq->max_active = wq->saved_max_active;
 		pwq->max_active = 0;
 	}
-	spin_unlock(&pwq->pool->lock);
+	spin_unlock_irq(&pwq->pool->lock);
 }
 static void init_and_link_pwq(struct pool_workqueue *pwq,
 	INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn);
 	mutex_lock(&wq->mutex);
-	spin_lock_irq(&pwq_lock);
 	/*
 	 * Set the matching work_color.  This is synchronized with
 	pwq_adjust_max_active(pwq);
 	/* link in @pwq */
+	spin_lock_irq(&pwq_lock);
 	list_add_rcu(&pwq->pwqs_node, &wq->pwqs);
 	spin_unlock_irq(&pwq_lock);
 	mutex_unlock(&wq->mutex);
 }
 	 */
 	mutex_lock(&wq_pool_mutex);
-	spin_lock_irq(&pwq_lock);
+	mutex_lock(&wq->mutex);
 	for_each_pwq(pwq, wq)
 		pwq_adjust_max_active(pwq);
-	spin_unlock_irq(&pwq_lock);
+	mutex_unlock(&wq->mutex);
 	list_add(&wq->list, &workqueues);
 	max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
-	spin_lock_irq(&pwq_lock);
+	mutex_lock(&wq->mutex);
 	wq->saved_max_active = max_active;
 	for_each_pwq(pwq, wq)
 		pwq_adjust_max_active(pwq);
-	spin_unlock_irq(&pwq_lock);
+	mutex_unlock(&wq->mutex);
 }
 EXPORT_SYMBOL_GPL(workqueue_set_max_active);
  * pool->worklist.
  *
  * CONTEXT:
- * Grabs and releases wq_pool_mutex, pwq_lock and pool->lock's.
+ * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
  */
 void freeze_workqueues_begin(void)
 {
 		spin_unlock_irq(&pool->lock);
 	}
-	/* suppress further executions by setting max_active to zero */
-	spin_lock_irq(&pwq_lock);
 	list_for_each_entry(wq, &workqueues, list) {
+		mutex_lock(&wq->mutex);
 		for_each_pwq(pwq, wq)
 			pwq_adjust_max_active(pwq);
+		mutex_unlock(&wq->mutex);
 	}
-	spin_unlock_irq(&pwq_lock);
 	mutex_unlock(&wq_pool_mutex);
 }
  * frozen works are transferred to their respective pool worklists.
  *
  * CONTEXT:
- * Grabs and releases wq_pool_mutex, pwq_lock and pool->lock's.
+ * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
  */
 void thaw_workqueues(void)
 {
 	}
 	/* restore max_active and repopulate worklist */
-	spin_lock_irq(&pwq_lock);
 	list_for_each_entry(wq, &workqueues, list) {
+		mutex_lock(&wq->mutex);
 		for_each_pwq(pwq, wq)
 			pwq_adjust_max_active(pwq);
+		mutex_unlock(&wq->mutex);
 	}
-	spin_unlock_irq(&pwq_lock);
 	workqueue_freezing = false;
 out_unlock:

workqueue: protect wq->saved_max_active with wq->mutex

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