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cn_queue.c

/*
 *    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
 * (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>

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;

      d->callback(d->callback_priv);

      d->destruct_data(d->ddata);
      d->ddata = NULL;

      kfree(d->free);
}

static struct cn_callback_entry *cn_queue_alloc_callback_entry(char *name, struct cb_id *id, void (*callback)(void *))
{
      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)
{
      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)(void *))
{
      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->nls = dev->nls;
      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);

      dev->nls = nls;
      dev->netlink_groups = 0;

      dev->cn_queue = create_workqueue(dev->name);
      if (!dev->cn_queue) {
            kfree(dev);
            return NULL;
      }

      return dev;
}

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

      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;
}

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