workqueue: introduce numa_pwq_tbl_install()

Factor out pool_workqueue linking and installation into numa_pwq_tbl[] from apply_workqueue_attrs() into numa_pwq_tbl_install(). link_pwq() is made safe to call multiple times. numa_pwq_tbl_install() links the pwq, installs it into numa_pwq_tbl[] at the specified node and returns the old entry. @last_pwq is removed from link_pwq() as the return value of the new function can be used instead. This is to prepare for NUMA affinity support for unbound workqueues.

Tejun Heo committed 13 years ago

Commit 1befcf31 parent e50aba91 file · +26 −9Browse files

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

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kernel/workqueue.c+26−9

 	pwq->flush_color = -1;
 	pwq->refcnt = 1;
 	INIT_LIST_HEAD(&pwq->delayed_works);
+	INIT_LIST_HEAD(&pwq->pwqs_node);
 	INIT_LIST_HEAD(&pwq->mayday_node);
 	INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn);
 }
 /* sync @pwq with the current state of its associated wq and link it */
-static void link_pwq(struct pool_workqueue *pwq,
+static void link_pwq(struct pool_workqueue *pwq)
-		     struct pool_workqueue **p_last_pwq)
 {
 	struct workqueue_struct *wq = pwq->wq;
 	lockdep_assert_held(&wq->mutex);
+	/* may be called multiple times, ignore if already linked */
+	if (!list_empty(&pwq->pwqs_node))
+		return;
 	/*
 	 * Set the matching work_color.  This is synchronized with
 	 * wq->mutex to avoid confusing flush_workqueue().
 	 */
-	if (p_last_pwq)
-		*p_last_pwq = first_pwq(wq);
 	pwq->work_color = wq->work_color;
 	/* sync max_active to the current setting */
 	return pwq;
 }
+/* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */
+static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq,
+						   int node,
+						   struct pool_workqueue *pwq)
+{
+	struct pool_workqueue *old_pwq;
+	lockdep_assert_held(&wq->mutex);
+	/* link_pwq() can handle duplicate calls */
+	link_pwq(pwq);
+	old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
+	rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq);
+	return old_pwq;
+}
 /**
  * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
  * @wq: the target workqueue
 			  const struct workqueue_attrs *attrs)
 {
 	struct workqueue_attrs *new_attrs;
-	struct pool_workqueue *pwq, *last_pwq;
+	struct pool_workqueue *pwq, *last_pwq = NULL;
 	int node, ret;
 	/* only unbound workqueues can change attributes */
 	mutex_lock(&wq->mutex);
-	link_pwq(pwq, &last_pwq);
 	copy_workqueue_attrs(wq->unbound_attrs, new_attrs);
 	for_each_node(node)
-		rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq);
+		last_pwq = numa_pwq_tbl_install(wq, node, pwq);
 	mutex_unlock(&wq->mutex);
 			init_pwq(pwq, wq, &cpu_pools[highpri]);
 			mutex_lock(&wq->mutex);
-			link_pwq(pwq, NULL);
+			link_pwq(pwq);
 			mutex_unlock(&wq->mutex);
 		}
 		return 0;