cn_queue.c

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/*
 *  cn_queue.c
 *
 * 2004+ Copyright (c) Evgeniy Polyakov <[email protected]>
 * 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) {
        pr_err("Failed to create new callback queue.\n");
        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)) {
        pr_info("Waiting for %s to become free: refcnt=%d.\n",
               dev->name, atomic_read(&dev->refcnt));
        msleep(1000);
    }

    kfree(dev);
    dev = NULL;
}