/*
* cn_queue.c
*
* 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
* 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
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/workqueue.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/skbuff.h>
#include <linux/suspend.h>
#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 =
container_of(work, struct cn_callback_entry, work);
struct cn_callback_data *d = &cbq->data;
struct cn_msg *msg = NLMSG_DATA(nlmsg_hdr(d->skb));
struct netlink_skb_parms *nsp = &NETLINK_CB(d->skb);
d->callback(msg, nsp);
kfree_skb(d->skb);
d->skb = NULL;
kfree(d->free);
}
static struct cn_callback_entry *
cn_queue_alloc_callback_entry(char *name, struct cb_id *id,
void (*callback)(struct cn_msg *, struct netlink_skb_parms *))
{
struct cn_callback_entry *cbq;
cbq = kzalloc(sizeof(*cbq), GFP_KERNEL);
if (!cbq) {
printk(KERN_ERR "Failed to create new callback queue.\n");
return NULL;
}
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)
{
/* 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);
}
int cn_cb_equal(struct cb_id *i1, struct cb_id *i2)
{
return ((i1->idx == i2->idx) && (i1->val == i2->val));
}
int cn_queue_add_callback(struct cn_queue_dev *dev, char *name, struct cb_id *id,
void (*callback)(struct cn_msg *, struct netlink_skb_parms *))
{
struct cn_callback_entry *cbq, *__cbq;
int found = 0;
cbq = cn_queue_alloc_callback_entry(name, id, callback);
if (!cbq)
return -ENOMEM;
atomic_inc(&dev->refcnt);
cbq->pdev = dev;
spin_lock_bh(&dev->queue_lock);
list_for_each_entry(__cbq, &dev->queue_list, callback_entry) {
if (cn_cb_equal(&__cbq->id.id, id)) {
found = 1;
break;
}
}
if (!found)
list_add_tail(&cbq->callback_entry, &dev->queue_list);
spin_unlock_bh(&dev->queue_lock);
if (found) {
cn_queue_free_callback(cbq);
atomic_dec(&dev->refcnt);
return -EINVAL;
}
cbq->seq = 0;
cbq->group = cbq->id.id.idx;
return 0;
}
void cn_queue_del_callback(struct cn_queue_dev *dev, struct cb_id *id)
{
struct cn_callback_entry *cbq, *n;
int found = 0;
spin_lock_bh(&dev->queue_lock);
list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry) {
if (cn_cb_equal(&cbq->id.id, id)) {
list_del(&cbq->callback_entry);
found = 1;
break;
}
}
spin_unlock_bh(&dev->queue_lock);
if (found) {
cn_queue_free_callback(cbq);
atomic_dec(&dev->refcnt);
}
}
struct cn_queue_dev *cn_queue_alloc_dev(char *name, struct sock *nls)
{
struct cn_queue_dev *dev;
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (!dev)
return NULL;
snprintf(dev->name, sizeof(dev->name), "%s", name);
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;
INIT_WORK(&dev->wq_creation, cn_queue_create);
return dev;
}
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);
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)
list_del(&cbq->callback_entry);
spin_unlock_bh(&dev->queue_lock);
while (atomic_read(&dev->refcnt)) {
printk(KERN_INFO "Waiting for %s to become free: refcnt=%d.\n",
dev->name, atomic_read(&dev->refcnt));
msleep(1000);
}
kfree(dev);
dev = NULL;
}
