workqueue: separate out and refactor the locking of applying attrs
Applying attrs requires two locks: get_online_cpus() and wq_pool_mutex,
and this code is duplicated at two places (apply_workqueue_attrs() and
workqueue_set_unbound_cpumask()). So we separate out this locking
code into apply_wqattrs_[un]lock() and do a minor refactor on
apply_workqueue_attrs().
The apply_wqattrs_[un]lock() will be also used on later patch for
ensuring attrs changes are properly synchronized.
tj: minor updates to comments
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 4a9f65b..72c1adb 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3621,6 +3621,46 @@
mutex_unlock(&ctx->wq->mutex);
}
+static void apply_wqattrs_lock(void)
+{
+ /* CPUs should stay stable across pwq creations and installations */
+ get_online_cpus();
+ mutex_lock(&wq_pool_mutex);
+}
+
+static void apply_wqattrs_unlock(void)
+{
+ mutex_unlock(&wq_pool_mutex);
+ put_online_cpus();
+}
+
+static int apply_workqueue_attrs_locked(struct workqueue_struct *wq,
+ const struct workqueue_attrs *attrs)
+{
+ struct apply_wqattrs_ctx *ctx;
+ int ret = -ENOMEM;
+
+ /* only unbound workqueues can change attributes */
+ if (WARN_ON(!(wq->flags & WQ_UNBOUND)))
+ return -EINVAL;
+
+ /* creating multiple pwqs breaks ordering guarantee */
+ if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs)))
+ return -EINVAL;
+
+ ctx = apply_wqattrs_prepare(wq, attrs);
+
+ /* the ctx has been prepared successfully, let's commit it */
+ if (ctx) {
+ apply_wqattrs_commit(ctx);
+ ret = 0;
+ }
+
+ apply_wqattrs_cleanup(ctx);
+
+ return ret;
+}
+
/**
* apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
* @wq: the target workqueue
@@ -3640,37 +3680,11 @@
int apply_workqueue_attrs(struct workqueue_struct *wq,
const struct workqueue_attrs *attrs)
{
- struct apply_wqattrs_ctx *ctx;
- int ret = -ENOMEM;
+ int ret;
- /* only unbound workqueues can change attributes */
- if (WARN_ON(!(wq->flags & WQ_UNBOUND)))
- return -EINVAL;
-
- /* creating multiple pwqs breaks ordering guarantee */
- if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs)))
- return -EINVAL;
-
- /*
- * CPUs should stay stable across pwq creations and installations.
- * Pin CPUs, determine the target cpumask for each node and create
- * pwqs accordingly.
- */
- get_online_cpus();
- mutex_lock(&wq_pool_mutex);
-
- ctx = apply_wqattrs_prepare(wq, attrs);
-
- /* the ctx has been prepared successfully, let's commit it */
- if (ctx) {
- apply_wqattrs_commit(ctx);
- ret = 0;
- }
-
- mutex_unlock(&wq_pool_mutex);
- put_online_cpus();
-
- apply_wqattrs_cleanup(ctx);
+ apply_wqattrs_lock();
+ ret = apply_workqueue_attrs_locked(wq, attrs);
+ apply_wqattrs_unlock();
return ret;
}
@@ -4799,10 +4813,9 @@
if (!zalloc_cpumask_var(&saved_cpumask, GFP_KERNEL))
return -ENOMEM;
- get_online_cpus();
cpumask_and(cpumask, cpumask, cpu_possible_mask);
if (!cpumask_empty(cpumask)) {
- mutex_lock(&wq_pool_mutex);
+ apply_wqattrs_lock();
/* save the old wq_unbound_cpumask. */
cpumask_copy(saved_cpumask, wq_unbound_cpumask);
@@ -4815,9 +4828,8 @@
if (ret < 0)
cpumask_copy(wq_unbound_cpumask, saved_cpumask);
- mutex_unlock(&wq_pool_mutex);
+ apply_wqattrs_unlock();
}
- put_online_cpus();
free_cpumask_var(saved_cpumask);
return ret;
