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/*

 * Equalizer Load-balancer for serial network interfaces.

 *

 * (c) Copyright 1995 Simon "Guru Aleph-Null" Janes

 * NCM: Network and Communications Management, Inc.

 *

 * (c) Copyright 2002 David S. Miller (davem@redhat.com)

 *

 *      This software may be used and distributed according to the terms

 *      of the GNU General Public License, incorporated herein by reference.

 *

 * The author may be reached as simon@ncm.com, or C/O

 *    NCM

 *    Attn: Simon Janes

 *    6803 Whittier Ave

 *    McLean VA 22101

 *    Phone: 1-703-847-0040 ext 103

 */

/*

 * Sources:

 *   skeleton.c by Donald Becker.

 * Inspirations:

 *   The Harried and Overworked Alan Cox

 * Conspiracies:

 *   The Alan Cox and Mike McLagan plot to get someone else to do the code,

 *   which turned out to be me.

 */

/*

 * $Log: eql.c,v $

 * Revision 1.2  1996/04/11 17:51:52  guru

 * Added one-line eql_remove_slave patch.

 *

 * Revision 1.1  1996/04/11 17:44:17  guru

 * Initial revision

 *

 * Revision 3.13  1996/01/21  15:17:18  alan

 * tx_queue_len changes.

 * reformatted.

 *

 * Revision 3.12  1995/03/22  21:07:51  anarchy

 * Added capable() checks on configuration.

 * Moved header file.

 *

 * Revision 3.11  1995/01/19  23:14:31  guru

 *                    slave_load = (ULONG_MAX - (ULONG_MAX / 2)) -

 *                      (priority_Bps) + bytes_queued * 8;

 *

 * Revision 3.10  1995/01/19  23:07:53  guru

 * back to

 *                    slave_load = (ULONG_MAX - (ULONG_MAX / 2)) -

 *                      (priority_Bps) + bytes_queued;

 *

 * Revision 3.9  1995/01/19  22:38:20  guru

 *                    slave_load = (ULONG_MAX - (ULONG_MAX / 2)) -

 *                      (priority_Bps) + bytes_queued * 4;

 *

 * Revision 3.8  1995/01/19  22:30:55  guru

 *       slave_load = (ULONG_MAX - (ULONG_MAX / 2)) -

 *                      (priority_Bps) + bytes_queued * 2;

 *

 * Revision 3.7  1995/01/19  21:52:35  guru

 * printk's trimmed out.

 *

 * Revision 3.6  1995/01/19  21:49:56  guru

 * This is working pretty well. I gained 1 K/s in speed.. now it's just

 * robustness and printk's to be diked out.

 *

 * Revision 3.5  1995/01/18  22:29:59  guru

 * still crashes the kernel when the lock_wait thing is woken up.

 *

 * Revision 3.4  1995/01/18  21:59:47  guru

 * Broken set-bit locking snapshot

 *

 * Revision 3.3  1995/01/17  22:09:18  guru

 * infinite sleep in a lock somewhere..

 *

 * Revision 3.2  1995/01/15  16:46:06  guru

 * Log trimmed of non-pertinent 1.x branch messages

 *

 * Revision 3.1  1995/01/15  14:41:45  guru

 * New Scheduler and timer stuff...

 *

 * Revision 1.15  1995/01/15  14:29:02  guru

 * Will make 1.14 (now 1.15) the 3.0 branch, and the 1.12 the 2.0 branch, the one

 * with the dumber scheduler

 *

 * Revision 1.14  1995/01/15  02:37:08  guru

 * shock.. the kept-new-versions could have zonked working

 * stuff.. shudder

 *

 * Revision 1.13  1995/01/15  02:36:31  guru

 * big changes

 *

 *      scheduler was torn out and replaced with something smarter

 *

 *      global names not prefixed with eql_ were renamed to protect

 *      against namespace collisions

 *

 *      a few more abstract interfaces were added to facilitate any

 *      potential change of datastructure.  the driver is still using

 *      a linked list of slaves.  going to a heap would be a bit of

 *      an overkill.

 *

 *      this compiles fine with no warnings.

 *

 *      the locking mechanism and timer stuff must be written however,

 *      this version will not work otherwise

 *

 * Sorry, I had to rewrite most of this for 2.5.x -DaveM

 */

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/timer.h>

#include <linux/netdevice.h>

#include <net/net_namespace.h>

#include <linux/if.h>

#include <linux/if_arp.h>

#include <linux/if_eql.h>

#include <asm/uaccess.h>

static int eql_open(struct net_device *dev);

static int eql_close(struct net_device *dev);

static int eql_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd);

static int eql_slave_xmit(struct sk_buff *skb, struct net_device *dev);

#define eql_is_slave(dev)       ((dev->flags & IFF_SLAVE) == IFF_SLAVE)

#define eql_is_master(dev)      ((dev->flags & IFF_MASTER) == IFF_MASTER)

static void eql_kill_one_slave(slave_queue_t *queue, slave_t *slave);

static void eql_timer(unsigned long param)

{

        equalizer_t *eql = (equalizer_t *) param;

        struct list_head *this, *tmp, *head;

        spin_lock_bh(&eql->queue.lock);

        head = &eql->queue.all_slaves;

        list_for_each_safe(this, tmp, head) {

                slave_t *slave = list_entry(this, slave_t, list);

                if ((slave->dev->flags & IFF_UP) == IFF_UP) {

                        slave->bytes_queued -= slave->priority_Bps;

                        if (slave->bytes_queued < 0)

                                slave->bytes_queued = 0;

                } else {

                        eql_kill_one_slave(&eql->queue, slave);

                }

        }

        spin_unlock_bh(&eql->queue.lock);

        eql->timer.expires = jiffies + EQL_DEFAULT_RESCHED_IVAL;

        add_timer(&eql->timer);

}

static char version[] __initdata =

        "Equalizer2002: Simon Janes (simon@ncm.com) and David S. Miller (davem@redhat.com)\n";

static void __init eql_setup(struct net_device *dev)

{

        equalizer_t *eql = netdev_priv(dev);

        init_timer(&eql->timer);

        eql->timer.data         = (unsigned long) eql;

        eql->timer.expires      = jiffies + EQL_DEFAULT_RESCHED_IVAL;

        eql->timer.function     = eql_timer;

        spin_lock_init(&eql->queue.lock);

        INIT_LIST_HEAD(&eql->queue.all_slaves);

        eql->queue.master_dev   = dev;

        dev->open               = eql_open;

        dev->stop               = eql_close;

        dev->do_ioctl           = eql_ioctl;

        dev->hard_start_xmit    = eql_slave_xmit;

        /*

         *      Now we undo some of the things that eth_setup does

         *      that we don't like

         */

        dev->mtu                = EQL_DEFAULT_MTU;      /* set to 576 in if_eql.h */

        dev->flags              = IFF_MASTER;

        dev->type               = ARPHRD_SLIP;

        dev->tx_queue_len       = 5;            /* Hands them off fast */

}

static int eql_open(struct net_device *dev)

{

        equalizer_t *eql = netdev_priv(dev);

        /* XXX We should force this off automatically for the user. */

        printk(KERN_INFO "%s: remember to turn off Van-Jacobson compression on "

               "your slave devices.\n", dev->name);

        BUG_ON(!list_empty(&eql->queue.all_slaves));

        eql->min_slaves = 1;

        eql->max_slaves = EQL_DEFAULT_MAX_SLAVES; /* 4 usually... */

        add_timer(&eql->timer);

        return 0;

}

static void eql_kill_one_slave(slave_queue_t *queue, slave_t *slave)

{

        list_del(&slave->list);

        queue->num_slaves--;

        slave->dev->flags &= ~IFF_SLAVE;

        dev_put(slave->dev);

        kfree(slave);

}

static void eql_kill_slave_queue(slave_queue_t *queue)

{

        struct list_head *head, *tmp, *this;

        spin_lock_bh(&queue->lock);

        head = &queue->all_slaves;

        list_for_each_safe(this, tmp, head) {

                slave_t *s = list_entry(this, slave_t, list);

                eql_kill_one_slave(queue, s);

        }

        spin_unlock_bh(&queue->lock);

}

static int eql_close(struct net_device *dev)

{

        equalizer_t *eql = netdev_priv(dev);

        /*

         *      The timer has to be stopped first before we start hacking away

         *      at the data structure it scans every so often...

         */

        del_timer_sync(&eql->timer);

        eql_kill_slave_queue(&eql->queue);

        return 0;

}

static int eql_enslave(struct net_device *dev,  slaving_request_t __user *srq);

static int eql_emancipate(struct net_device *dev, slaving_request_t __user *srq);

static int eql_g_slave_cfg(struct net_device *dev, slave_config_t __user *sc);

static int eql_s_slave_cfg(struct net_device *dev, slave_config_t __user *sc);

static int eql_g_master_cfg(struct net_device *dev, master_config_t __user *mc);

static int eql_s_master_cfg(struct net_device *dev, master_config_t __user *mc);

static int eql_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)

{

        if (cmd != EQL_GETMASTRCFG && cmd != EQL_GETSLAVECFG &&

            !capable(CAP_NET_ADMIN))

                return -EPERM;

        switch (cmd) {

                case EQL_ENSLAVE:

                        return eql_enslave(dev, ifr->ifr_data);

                case EQL_EMANCIPATE:

                        return eql_emancipate(dev, ifr->ifr_data);

                case EQL_GETSLAVECFG:

                        return eql_g_slave_cfg(dev, ifr->ifr_data);

                case EQL_SETSLAVECFG:

                        return eql_s_slave_cfg(dev, ifr->ifr_data);

                case EQL_GETMASTRCFG:

                        return eql_g_master_cfg(dev, ifr->ifr_data);

                case EQL_SETMASTRCFG:

                        return eql_s_master_cfg(dev, ifr->ifr_data);

                default:

                        return -EOPNOTSUPP;

        };

}

/* queue->lock must be held */

static slave_t *__eql_schedule_slaves(slave_queue_t *queue)

{

        unsigned long best_load = ~0UL;

        struct list_head *this, *tmp, *head;

        slave_t *best_slave;

        best_slave = NULL;

        /* Make a pass to set the best slave. */

        head = &queue->all_slaves;

        list_for_each_safe(this, tmp, head) {

                slave_t *slave = list_entry(this, slave_t, list);

                unsigned long slave_load, bytes_queued, priority_Bps;

                /* Go through the slave list once, updating best_slave

                 * whenever a new best_load is found.

                 */

                bytes_queued = slave->bytes_queued;

                priority_Bps = slave->priority_Bps;

                if ((slave->dev->flags & IFF_UP) == IFF_UP) {

                        slave_load = (~0UL - (~0UL / 2)) -

                                (priority_Bps) + bytes_queued * 8;

                        if (slave_load < best_load) {

                                best_load = slave_load;

                                best_slave = slave;

                        }

                } else {

                        /* We found a dead slave, kill it. */

                        eql_kill_one_slave(queue, slave);

                }

        }

        return best_slave;

}

static int eql_slave_xmit(struct sk_buff *skb, struct net_device *dev)

{

        equalizer_t *eql = netdev_priv(dev);

        slave_t *slave;

        spin_lock(&eql->queue.lock);

        slave = __eql_schedule_slaves(&eql->queue);

        if (slave) {

                struct net_device *slave_dev = slave->dev;

                skb->dev = slave_dev;

                skb->priority = 1;

                slave->bytes_queued += skb->len;

                dev_queue_xmit(skb);

                dev->stats.tx_packets++;

        } else {

                dev->stats.tx_dropped++;

                dev_kfree_skb(skb);

        }

        spin_unlock(&eql->queue.lock);

        return 0;

}

/*

 *      Private ioctl functions

 */

/* queue->lock must be held */

static slave_t *__eql_find_slave_dev(slave_queue_t *queue, struct net_device *dev)

{

        struct list_head *this, *head;

        head = &queue->all_slaves;

        list_for_each(this, head) {

                slave_t *slave = list_entry(this, slave_t, list);

                if (slave->dev == dev)

                        return slave;

        }

        return NULL;

}

static inline int eql_is_full(slave_queue_t *queue)

{

        equalizer_t *eql = netdev_priv(queue->master_dev);

        if (queue->num_slaves >= eql->max_slaves)

                return 1;

        return 0;

}

/* queue->lock must be held */

static int __eql_insert_slave(slave_queue_t *queue, slave_t *slave)

{

        if (!eql_is_full(queue)) {

                slave_t *duplicate_slave = NULL;

                duplicate_slave = __eql_find_slave_dev(queue, slave->dev);

                if (duplicate_slave)

                        eql_kill_one_slave(queue, duplicate_slave);

                list_add(&slave->list, &queue->all_slaves);

                queue->num_slaves++;

                slave->dev->flags |= IFF_SLAVE;

                return 0;

        }

        return -ENOSPC;

}

static int eql_enslave(struct net_device *master_dev, slaving_request_t __user *srqp)

{

        struct net_device *slave_dev;

        slaving_request_t srq;

        if (copy_from_user(&srq, srqp, sizeof (slaving_request_t)))

                return -EFAULT;

        slave_dev  = dev_get_by_name(&init_net, srq.slave_name);

        if (slave_dev) {

                if ((master_dev->flags & IFF_UP) == IFF_UP) {

                        /* slave is not a master & not already a slave: */

                        if (!eql_is_master(slave_dev) &&

                            !eql_is_slave(slave_dev)) {

                                slave_t *s = kmalloc(sizeof(*s), GFP_KERNEL);

                                equalizer_t *eql = netdev_priv(master_dev);

                                int ret;

                                if (!s) {

                                        dev_put(slave_dev);

                                        return -ENOMEM;

                                }

                                memset(s, 0, sizeof(*s));

                                s->dev = slave_dev;

                                s->priority = srq.priority;

                                s->priority_bps = srq.priority;

                                s->priority_Bps = srq.priority / 8;

                                spin_lock_bh(&eql->queue.lock);

                                ret = __eql_insert_slave(&eql->queue, s);

                                if (ret) {

                                        dev_put(slave_dev);

                                        kfree(s);

                                }

                                spin_unlock_bh(&eql->queue.lock);

                                return ret;

                        }

                }

                dev_put(slave_dev);

        }

        return -EINVAL;

}

static int eql_emancipate(struct net_device *master_dev, slaving_request_t __user *srqp)

{

        equalizer_t *eql = netdev_priv(master_dev);

        struct net_device *slave_dev;

        slaving_request_t srq;

        int ret;

        if (copy_from_user(&srq, srqp, sizeof (slaving_request_t)))

                return -EFAULT;

        slave_dev = dev_get_by_name(&init_net, srq.slave_name);

        ret = -EINVAL;

        if (slave_dev) {

                spin_lock_bh(&eql->queue.lock);

                if (eql_is_slave(slave_dev)) {

                        slave_t *slave = __eql_find_slave_dev(&eql->queue,

                                                              slave_dev);

                        if (slave) {

                                eql_kill_one_slave(&eql->queue, slave);

                                ret = 0;

                        }

                }

                dev_put(slave_dev);

                spin_unlock_bh(&eql->queue.lock);

        }

        return ret;

}

static int eql_g_slave_cfg(struct net_device *dev, slave_config_t __user *scp)

{

        equalizer_t *eql = netdev_priv(dev);

        slave_t *slave;

        struct net_device *slave_dev;

        slave_config_t sc;

        int ret;

        if (copy_from_user(&sc, scp, sizeof (slave_config_t)))

                return -EFAULT;

        slave_dev = dev_get_by_name(&init_net, sc.slave_name);

        if (!slave_dev)

                return -ENODEV;

        ret = -EINVAL;

        spin_lock_bh(&eql->queue.lock);

        if (eql_is_slave(slave_dev)) {

                slave = __eql_find_slave_dev(&eql->queue, slave_dev);

                if (slave) {

                        sc.priority = slave->priority;

                        ret = 0;

                }

        }

        spin_unlock_bh(&eql->queue.lock);

        dev_put(slave_dev);

        if (!ret && copy_to_user(scp, &sc, sizeof (slave_config_t)))

                ret = -EFAULT;

        return ret;

}

static int eql_s_slave_cfg(struct net_device *dev, slave_config_t __user *scp)

{

        slave_t *slave;

        equalizer_t *eql;

        struct net_device *slave_dev;

        slave_config_t sc;

        int ret;

        if (copy_from_user(&sc, scp, sizeof (slave_config_t)))

                return -EFAULT;

        slave_dev = dev_get_by_name(&init_net, sc.slave_name);

        if (!slave_dev)

                return -ENODEV;

        ret = -EINVAL;

        eql = netdev_priv(dev);

        spin_lock_bh(&eql->queue.lock);

        if (eql_is_slave(slave_dev)) {

                slave = __eql_find_slave_dev(&eql->queue, slave_dev);

                if (slave) {

                        slave->priority = sc.priority;

                        slave->priority_bps = sc.priority;

                        slave->priority_Bps = sc.priority / 8;

                        ret = 0;

                }

        }

        spin_unlock_bh(&eql->queue.lock);

        return ret;

}

static int eql_g_master_cfg(struct net_device *dev, master_config_t __user *mcp)

{

        equalizer_t *eql;

        master_config_t mc;

        if (eql_is_master(dev)) {

                eql = netdev_priv(dev);

                mc.max_slaves = eql->max_slaves;

                mc.min_slaves = eql->min_slaves;

                if (copy_to_user(mcp, &mc, sizeof (master_config_t)))

                        return -EFAULT;

                return 0;

        }

        return -EINVAL;

}

static int eql_s_master_cfg(struct net_device *dev, master_config_t __user *mcp)

{

        equalizer_t *eql;

        master_config_t mc;

        if (copy_from_user(&mc, mcp, sizeof (master_config_t)))

                return -EFAULT;

        if (eql_is_master(dev)) {

                eql = netdev_priv(dev);

                eql->max_slaves = mc.max_slaves;

                eql->min_slaves = mc.min_slaves;

                return 0;

        }

        return -EINVAL;

}

static struct net_device *dev_eql;

static int __init eql_init_module(void)

{

        int err;

        printk(version);

        dev_eql = alloc_netdev(sizeof(equalizer_t), "eql", eql_setup);

        if (!dev_eql)

                return -ENOMEM;

        err = register_netdev(dev_eql);

        if (err)

                free_netdev(dev_eql);

        return err;

}

static void __exit eql_cleanup_module(void)

{

        unregister_netdev(dev_eql);

        free_netdev(dev_eql);

}

module_init(eql_init_module);

module_exit(eql_cleanup_module);

MODULE_LICENSE("GPL");