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path: root/drivers/connector/cn_queue.c
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Diffstat (limited to 'drivers/connector/cn_queue.c')
-rw-r--r--drivers/connector/cn_queue.c80
1 files changed, 69 insertions, 11 deletions
diff --git a/drivers/connector/cn_queue.c b/drivers/connector/cn_queue.c
index b6fe7e7a2c2f..c769ef269fb5 100644
--- a/drivers/connector/cn_queue.c
+++ b/drivers/connector/cn_queue.c
@@ -1,9 +1,9 @@
/*
* cn_queue.c
- *
+ *
* 2004-2005 Copyright (c) Evgeniy Polyakov <johnpol@2ka.mipt.ru>
* All rights reserved.
- *
+ *
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
@@ -31,6 +31,48 @@
#include <linux/connector.h>
#include <linux/delay.h>
+
+/*
+ * This job is sent to the kevent workqueue.
+ * While no event is once sent to any callback, the connector workqueue
+ * is not created to avoid a useless waiting kernel task.
+ * Once the first event is received, we create this dedicated workqueue which
+ * is necessary because the flow of data can be high and we don't want
+ * to encumber keventd with that.
+ */
+static void cn_queue_create(struct work_struct *work)
+{
+ struct cn_queue_dev *dev;
+
+ dev = container_of(work, struct cn_queue_dev, wq_creation);
+
+ dev->cn_queue = create_singlethread_workqueue(dev->name);
+ /* If we fail, we will use keventd for all following connector jobs */
+ WARN_ON(!dev->cn_queue);
+}
+
+/*
+ * Queue a data sent to a callback.
+ * If the connector workqueue is already created, we queue the job on it.
+ * Otherwise, we queue the job to kevent and queue the connector workqueue
+ * creation too.
+ */
+int queue_cn_work(struct cn_callback_entry *cbq, struct work_struct *work)
+{
+ struct cn_queue_dev *pdev = cbq->pdev;
+
+ if (likely(pdev->cn_queue))
+ return queue_work(pdev->cn_queue, work);
+
+ /* Don't create the connector workqueue twice */
+ if (atomic_inc_return(&pdev->wq_requested) == 1)
+ schedule_work(&pdev->wq_creation);
+ else
+ atomic_dec(&pdev->wq_requested);
+
+ return schedule_work(work);
+}
+
void cn_queue_wrapper(struct work_struct *work)
{
struct cn_callback_entry *cbq =
@@ -58,14 +100,17 @@ static struct cn_callback_entry *cn_queue_alloc_callback_entry(char *name, struc
snprintf(cbq->id.name, sizeof(cbq->id.name), "%s", name);
memcpy(&cbq->id.id, id, sizeof(struct cb_id));
cbq->data.callback = callback;
-
+
INIT_WORK(&cbq->work, &cn_queue_wrapper);
return cbq;
}
static void cn_queue_free_callback(struct cn_callback_entry *cbq)
{
- flush_workqueue(cbq->pdev->cn_queue);
+ /* The first jobs have been sent to kevent, flush them too */
+ flush_scheduled_work();
+ if (cbq->pdev->cn_queue)
+ flush_workqueue(cbq->pdev->cn_queue);
kfree(cbq);
}
@@ -143,14 +188,11 @@ struct cn_queue_dev *cn_queue_alloc_dev(char *name, struct sock *nls)
atomic_set(&dev->refcnt, 0);
INIT_LIST_HEAD(&dev->queue_list);
spin_lock_init(&dev->queue_lock);
+ init_waitqueue_head(&dev->wq_created);
dev->nls = nls;
- dev->cn_queue = create_singlethread_workqueue(dev->name);
- if (!dev->cn_queue) {
- kfree(dev);
- return NULL;
- }
+ INIT_WORK(&dev->wq_creation, cn_queue_create);
return dev;
}
@@ -158,9 +200,25 @@ struct cn_queue_dev *cn_queue_alloc_dev(char *name, struct sock *nls)
void cn_queue_free_dev(struct cn_queue_dev *dev)
{
struct cn_callback_entry *cbq, *n;
+ long timeout;
+ DEFINE_WAIT(wait);
+
+ /* Flush the first pending jobs queued on kevent */
+ flush_scheduled_work();
+
+ /* If the connector workqueue creation is still pending, wait for it */
+ prepare_to_wait(&dev->wq_created, &wait, TASK_UNINTERRUPTIBLE);
+ if (atomic_read(&dev->wq_requested) && !dev->cn_queue) {
+ timeout = schedule_timeout(HZ * 2);
+ if (!timeout && !dev->cn_queue)
+ WARN_ON(1);
+ }
+ finish_wait(&dev->wq_created, &wait);
- flush_workqueue(dev->cn_queue);
- destroy_workqueue(dev->cn_queue);
+ if (dev->cn_queue) {
+ flush_workqueue(dev->cn_queue);
+ destroy_workqueue(dev->cn_queue);
+ }
spin_lock_bh(&dev->queue_lock);
list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry)

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