// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2018, Intel Corporation. */

/* A common module to handle registrations and notifications for paravirtual
 * drivers to enable accelerated datapath and support VF live migration.
 *
 * The notifier and event handling code is based on netvsc driver.
 */

#include <linux/module.h>
#include <linux/etherdevice.h>
#include <uapi/linux/if_arp.h>
#include <linux/rtnetlink.h>
#include <linux/if_vlan.h>
#include <net/failover.h>

static LIST_HEAD(failover_list);
static DEFINE_SPINLOCK(failover_lock);

static struct net_device *failover_get_bymac(u8 *mac, struct failover_ops **ops)
{
        struct net_device *failover_dev;
        struct failover *failover;

        spin_lock(&failover_lock);
        list_for_each_entry(failover, &failover_list, list) {
                failover_dev = rtnl_dereference(failover->failover_dev);
                if (ether_addr_equal(failover_dev->perm_addr, mac)) {
                        *ops = rtnl_dereference(failover->ops);
                        spin_unlock(&failover_lock);
                        return failover_dev;
                }
        }
        spin_unlock(&failover_lock);
        return NULL;
}

/**
 * failover_slave_register - Register a slave netdev
 *
 * @slave_dev: slave netdev that is being registered
 *
 * Registers a slave device to a failover instance. Only ethernet devices
 * are supported.
 */
static int failover_slave_register(struct net_device *slave_dev)
{
        struct netdev_lag_upper_info lag_upper_info;
        struct net_device *failover_dev;
        struct failover_ops *fops;
        int err;

        if (slave_dev->type != ARPHRD_ETHER)
                goto done;

        ASSERT_RTNL();

        failover_dev = failover_get_bymac(slave_dev->perm_addr, &fops);
        if (!failover_dev)
                goto done;

        if (fops && fops->slave_pre_register &&
            fops->slave_pre_register(slave_dev, failover_dev))
                goto done;

        err = netdev_rx_handler_register(slave_dev, fops->slave_handle_frame,
                                         failover_dev);
        if (err) {
                netdev_err(slave_dev, "can not register failover rx handler (err = %d)\n",
                           err);
                goto done;
        }

        lag_upper_info.tx_type = NETDEV_LAG_TX_TYPE_ACTIVEBACKUP;
        err = netdev_master_upper_dev_link(slave_dev, failover_dev, NULL,
                                           &lag_upper_info, NULL);
        if (err) {
                netdev_err(slave_dev, "can not set failover device %s (err = %d)\n",
                           failover_dev->name, err);
                goto err_upper_link;
        }

        slave_dev->priv_flags |= (IFF_FAILOVER_SLAVE | IFF_NO_ADDRCONF);

        if (fops && fops->slave_register &&
            !fops->slave_register(slave_dev, failover_dev))
                return NOTIFY_OK;

        netdev_upper_dev_unlink(slave_dev, failover_dev);
        slave_dev->priv_flags &= ~(IFF_FAILOVER_SLAVE | IFF_NO_ADDRCONF);
err_upper_link:
        netdev_rx_handler_unregister(slave_dev);
done:
        return NOTIFY_DONE;
}

/**
 * failover_slave_unregister - Unregister a slave netdev
 *
 * @slave_dev: slave netdev that is being unregistered
 *
 * Unregisters a slave device from a failover instance.
 */
int failover_slave_unregister(struct net_device *slave_dev)
{
        struct net_device *failover_dev;
        struct failover_ops *fops;

        if (!netif_is_failover_slave(slave_dev))
                goto done;

        ASSERT_RTNL();

        failover_dev = failover_get_bymac(slave_dev->perm_addr, &fops);
        if (!failover_dev)
                goto done;

        if (fops && fops->slave_pre_unregister &&
            fops->slave_pre_unregister(slave_dev, failover_dev))
                goto done;

        netdev_rx_handler_unregister(slave_dev);
        netdev_upper_dev_unlink(slave_dev, failover_dev);
        slave_dev->priv_flags &= ~(IFF_FAILOVER_SLAVE | IFF_NO_ADDRCONF);

        if (fops && fops->slave_unregister &&
            !fops->slave_unregister(slave_dev, failover_dev))
                return NOTIFY_OK;

done:
        return NOTIFY_DONE;
}
EXPORT_SYMBOL_GPL(failover_slave_unregister);

static int failover_slave_link_change(struct net_device *slave_dev)
{
        struct net_device *failover_dev;
        struct failover_ops *fops;

        if (!netif_is_failover_slave(slave_dev))
                goto done;

        ASSERT_RTNL();

        failover_dev = failover_get_bymac(slave_dev->perm_addr, &fops);
        if (!failover_dev)
                goto done;

        if (!netif_running(failover_dev))
                goto done;

        if (fops && fops->slave_link_change &&
            !fops->slave_link_change(slave_dev, failover_dev))
                return NOTIFY_OK;

done:
        return NOTIFY_DONE;
}

static int failover_slave_name_change(struct net_device *slave_dev)
{
        struct net_device *failover_dev;
        struct failover_ops *fops;

        if (!netif_is_failover_slave(slave_dev))
                goto done;

        ASSERT_RTNL();

        failover_dev = failover_get_bymac(slave_dev->perm_addr, &fops);
        if (!failover_dev)
                goto done;

        if (!netif_running(failover_dev))
                goto done;

        if (fops && fops->slave_name_change &&
            !fops->slave_name_change(slave_dev, failover_dev))
                return NOTIFY_OK;

done:
        return NOTIFY_DONE;
}

static int
failover_event(struct notifier_block *this, unsigned long event, void *ptr)
{
        struct net_device *event_dev = netdev_notifier_info_to_dev(ptr);

        /* Skip parent events */
        if (netif_is_failover(event_dev))
                return NOTIFY_DONE;

        switch (event) {
        case NETDEV_REGISTER:
                return failover_slave_register(event_dev);
        case NETDEV_UNREGISTER:
                return failover_slave_unregister(event_dev);
        case NETDEV_UP:
        case NETDEV_DOWN:
        case NETDEV_CHANGE:
                return failover_slave_link_change(event_dev);
        case NETDEV_CHANGENAME:
                return failover_slave_name_change(event_dev);
        default:
                return NOTIFY_DONE;
        }
}

static struct notifier_block failover_notifier = {
        .notifier_call = failover_event,
};

static void
failover_existing_slave_register(struct net_device *failover_dev)
{
        struct net *net = dev_net(failover_dev);
        struct net_device *dev;

        rtnl_lock();
        for_each_netdev(net, dev) {
                if (netif_is_failover(dev))
                        continue;
                if (ether_addr_equal(failover_dev->perm_addr, dev->perm_addr))
                        failover_slave_register(dev);
        }
        rtnl_unlock();
}

/**
 * failover_register - Register a failover instance
 *
 * @dev: failover netdev
 * @ops: failover ops
 *
 * Allocate and register a failover instance for a failover netdev. ops
 * provides handlers for slave device register/unregister/link change/
 * name change events.
 *
 * Return: pointer to failover instance
 */
struct failover *failover_register(struct net_device *dev,
                                   struct failover_ops *ops)
{
        struct failover *failover;

        if (dev->type != ARPHRD_ETHER)
                return ERR_PTR(-EINVAL);

        failover = kzalloc_obj(*failover);
        if (!failover)
                return ERR_PTR(-ENOMEM);

        rcu_assign_pointer(failover->ops, ops);
        netdev_hold(dev, &failover->dev_tracker, GFP_KERNEL);
        dev->priv_flags |= IFF_FAILOVER;
        rcu_assign_pointer(failover->failover_dev, dev);

        spin_lock(&failover_lock);
        list_add_tail(&failover->list, &failover_list);
        spin_unlock(&failover_lock);

        netdev_info(dev, "failover master:%s registered\n", dev->name);

        failover_existing_slave_register(dev);

        return failover;
}
EXPORT_SYMBOL_GPL(failover_register);

/**
 * failover_unregister - Unregister a failover instance
 *
 * @failover: pointer to failover instance
 *
 * Unregisters and frees a failover instance.
 */
void failover_unregister(struct failover *failover)
{
        struct net_device *failover_dev;

        failover_dev = rcu_dereference(failover->failover_dev);

        netdev_info(failover_dev, "failover master:%s unregistered\n",
                    failover_dev->name);

        failover_dev->priv_flags &= ~IFF_FAILOVER;
        netdev_put(failover_dev, &failover->dev_tracker);

        spin_lock(&failover_lock);
        list_del(&failover->list);
        spin_unlock(&failover_lock);

        kfree(failover);
}
EXPORT_SYMBOL_GPL(failover_unregister);

static __init int
failover_init(void)
{
        register_netdevice_notifier(&failover_notifier);

        return 0;
}
module_init(failover_init);

static __exit
void failover_exit(void)
{
        unregister_netdevice_notifier(&failover_notifier);
}
module_exit(failover_exit);

MODULE_DESCRIPTION("Generic failover infrastructure/interface");
MODULE_LICENSE("GPL v2");