eql.c

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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 ([email protected])
 *
 *  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 [email protected], 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
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/capability.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.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 <linux/pkt_sched.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 netdev_tx_t 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(&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(&eql->queue.lock);

    eql->timer.expires = jiffies + EQL_DEFAULT_RESCHED_IVAL;
    add_timer(&eql->timer);
}

static const char version[] __initconst =
    "Equalizer2002: Simon Janes ([email protected]) and David S. Miller ([email protected])";

static const struct net_device_ops eql_netdev_ops = {
    .ndo_open   = eql_open,
    .ndo_stop   = eql_close,
    .ndo_do_ioctl   = eql_ioctl,
    .ndo_start_xmit = eql_slave_xmit,
};

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->netdev_ops     = &eql_netdev_ops;

    /*
     *  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 */
    dev->priv_flags        &= ~IFF_XMIT_DST_RELEASE;
}

static int eql_open(struct net_device *dev)
{
    equalizer_t *eql = netdev_priv(dev);

    /* XXX We should force this off automatically for the user. */
    netdev_info(dev,
            "remember to turn off Van-Jacobson compression on your slave devices\n");

    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 netdev_tx_t 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 = TC_PRIO_FILLER;
        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 NETDEV_TX_OK;
}

/*
 *  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);

    dev_put(slave_dev);

    return ret;
}

static int eql_g_master_cfg(struct net_device *dev, master_config_t __user *mcp)
{
    equalizer_t *eql;
    master_config_t mc;

    memset(&mc, 0, sizeof(master_config_t));

    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;

    pr_info("%s\n", 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");