[PATCH 22/31] workqueue: restructure __alloc_workqueue_key()

Tejun Heo
2013-03-02T03:28:38Z

* Move initialization and linking of pool_workqueues into
init_and_link_pwq().

* Make the failure path use destroy_workqueue() once pool_workqueue
initialization succeeds.

These changes are to prepare for dynamic management of pool_workqueues
and don't introduce any functional changes.

While at it, convert list_del(&wq->list) to list_del_init() as a
precaution as scheduled changes will make destruction more complex.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
kernel/workqueue.c | 67 +++++++++++++++++++++++++++++++-----------------------
1 file changed, 38 insertions(+), 29 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index bcc02bb..d0604ee 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3322,6 +3322,23 @@ fail:
return NULL;
}

+/* initialize @pwq which interfaces with @pool for @wq and link it in */
+static void init_and_link_pwq(struct pool_workqueue *pwq,
+ struct workqueue_struct *wq,
+ struct worker_pool *pool)
+{
+ BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK);
+
+ pwq->pool = pool;
+ pwq->wq = wq;
+ pwq->flush_color = -1;
+ pwq->max_active = wq->saved_max_active;
+ INIT_LIST_HEAD(&pwq->delayed_works);
+ INIT_LIST_HEAD(&pwq->mayday_node);
+
+ list_add_tail_rcu(&pwq->pwqs_node, &wq->pwqs);
+}
+
static int alloc_and_link_pwqs(struct workqueue_struct *wq)
{
bool highpri = wq->flags & WQ_HIGHPRI;
@@ -3338,23 +3355,23 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq)
struct worker_pool *cpu_pools =
per_cpu(cpu_worker_pools, cpu);

- pwq->pool = &cpu_pools[highpri];
- list_add_tail_rcu(&pwq->pwqs_node, &wq->pwqs);
+ init_and_link_pwq(pwq, wq, &cpu_pools[highpri]);
}
} else {
struct pool_workqueue *pwq;
+ struct worker_pool *pool;

pwq = kmem_cache_zalloc(pwq_cache, GFP_KERNEL);
if (!pwq)
return -ENOMEM;

- pwq->pool = get_unbound_pool(unbound_std_wq_attrs[highpri]);
- if (!pwq->pool) {
+ pool = get_unbound_pool(unbound_std_wq_attrs[highpri]);
+ if (!pool) {
kmem_cache_free(pwq_cache, pwq);
return -ENOMEM;
}

- list_add_tail_rcu(&pwq->pwqs_node, &wq->pwqs);
+ init_and_link_pwq(pwq, wq, pool);
}

return 0;
@@ -3399,7 +3416,7 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt,

wq = kzalloc(sizeof(*wq) + namelen, GFP_KERNEL);
if (!wq)
- goto err;
+ return NULL;

vsnprintf(wq->name, namelen, fmt, args1);
va_end(args);
@@ -3422,18 +3439,7 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
INIT_LIST_HEAD(&wq->list);

if (alloc_and_link_pwqs(wq) < 0)
- goto err;
-
- local_irq_disable();
- for_each_pwq(pwq, wq) {
- BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK);
- pwq->wq = wq;
- pwq->flush_color = -1;
- pwq->max_active = max_active;
- INIT_LIST_HEAD(&pwq->delayed_works);
- INIT_LIST_HEAD(&pwq->mayday_node);
- }
- local_irq_enable();
+ goto err_free_wq;

/*
* Workqueues which may be used during memory reclaim should
@@ -3442,16 +3448,19 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
if (flags & WQ_MEM_RECLAIM) {
struct worker *rescuer;

- wq->rescuer = rescuer = alloc_worker();
+ rescuer = alloc_worker();
if (!rescuer)
- goto err;
+ goto err_destroy;

rescuer->rescue_wq = wq;
rescuer->task = kthread_create(rescuer_thread, rescuer, "%s",
wq->name);
- if (IS_ERR(rescuer->task))
- goto err;
+ if (IS_ERR(rescuer->task)) {
+ kfree(rescuer);
+ goto err_destroy;
+ }

+ wq->rescuer = rescuer;
rescuer->task->flags |= PF_THREAD_BOUND;
wake_up_process(rescuer->task);
}
@@ -3472,12 +3481,12 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
spin_unlock_irq(&workqueue_lock);

return wq;
-err:
- if (wq) {
- free_pwqs(wq);
- kfree(wq->rescuer);
- kfree(wq);
- }
+
+err_free_wq:
+ kfree(wq);
+ return NULL;
+err_destroy:
+ destroy_workqueue(wq);
return NULL;
}
EXPORT_SYMBOL_GPL(__alloc_workqueue_key);
@@ -3519,7 +3528,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
* wq list is used to freeze wq, remove from list after
* flushing is complete in case freeze races us.
*/
- list_del(&wq->list);
+ list_del_init(&wq->list);

spin_unlock_irq(&workqueue_lock);

--
1.8.1.2