/*
   * 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
   */
  
  #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 (simon@ncm.com) and David S. Miller (davem@redhat.com)";
  
  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
  ");
  
  	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);
  
  		dev_hold(slave->dev);
  		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)
  		return -ENODEV;
  
  	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)
  				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)
  				kfree(s);
  
  			spin_unlock_bh(&eql->queue.lock);
  
  			return ret;
  		}
  	}
  
  	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);
  	if (!slave_dev)
  		return -ENODEV;
  
  	ret = -EINVAL;
  	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;
  		}
  	}
  	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);
  
  	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;
  
  	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
  ", 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");