/*
   * 	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>

  static struct cn_callback_entry *

  cn_queue_alloc_callback_entry(struct cn_queue_dev *dev, const 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.
  ");
  		return NULL;
  	}

  	atomic_set(&cbq->refcnt, 1);
  
  	atomic_inc(&dev->refcnt);
  	cbq->pdev = dev;

  	snprintf(cbq->id.name, sizeof(cbq->id.name), "%s", name);
  	memcpy(&cbq->id.id, id, sizeof(struct cb_id));

  	cbq->callback = callback;

  	return cbq;
  }

  void cn_queue_release_callback(struct cn_callback_entry *cbq)

  {

  	if (!atomic_dec_and_test(&cbq->refcnt))
  		return;
  
  	atomic_dec(&cbq->pdev->refcnt);

  	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, const 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(dev, name, id, callback);

  	if (!cbq)
  		return -ENOMEM;

  	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_release_callback(cbq);

  		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_release_callback(cbq);

  }

  struct cn_queue_dev *cn_queue_alloc_dev(const 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);
  
  	dev->nls = nls;

  	return dev;
  }
  
  void cn_queue_free_dev(struct cn_queue_dev *dev)
  {
  	struct cn_callback_entry *cbq, *n;

  	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.
  ",
  		       dev->name, atomic_read(&dev->refcnt));
  		msleep(1000);
  	}
  
  	kfree(dev);
  	dev = NULL;
  }