// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      cn_queue.c
 *
 * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
 * All rights reserved.
 */

#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,
                              const struct cb_id *id,
                              void (*callback)(struct cn_msg *,
                                               struct netlink_skb_parms *))
{
        struct cn_callback_entry *cbq;

        cbq = kzalloc_obj(*cbq);
        if (!cbq) {
                pr_err("Failed to create new callback queue.\n");
                return NULL;
        }

        refcount_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 (!refcount_dec_and_test(&cbq->refcnt))
                return;

        atomic_dec(&cbq->pdev->refcnt);
        kfree(cbq);
}

int cn_cb_equal(const struct cb_id *i1, const 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,
                          const 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, const 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_obj(*dev);
        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;
}