/*
   * net/sched/sch_prio.c	Simple 3-band priority "scheduler".
   *
   *		This program is free software; you can redistribute it and/or
   *		modify it under the terms of the GNU General Public License
   *		as published by the Free Software Foundation; either version
   *		2 of the License, or (at your option) any later version.
   *
   * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>

   * Fixes:       19990609: J Hadi Salim <hadi@nortelnetworks.com>:

   *              Init --  EINVAL when opt undefined
   */

  #include <linux/module.h>

  #include <linux/slab.h>

  #include <linux/types.h>
  #include <linux/kernel.h>

  #include <linux/string.h>

  #include <linux/errno.h>

  #include <linux/skbuff.h>

  #include <net/netlink.h>

  #include <net/pkt_sched.h>

  struct prio_sched_data {

  	int bands;

  	struct tcf_proto __rcu *filter_list;

  	u8  prio2band[TC_PRIO_MAX+1];
  	struct Qdisc *queues[TCQ_PRIO_BANDS];
  };
  
  
  static struct Qdisc *
  prio_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
  {
  	struct prio_sched_data *q = qdisc_priv(sch);
  	u32 band = skb->priority;
  	struct tcf_result res;

  	struct tcf_proto *fl;

  	int err;

  	*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;

  	if (TC_H_MAJ(skb->priority) != sch->handle) {

  		fl = rcu_dereference_bh(q->filter_list);

  		err = tc_classify(skb, fl, &res, false);

  #ifdef CONFIG_NET_CLS_ACT

  		switch (err) {

  		case TC_ACT_STOLEN:
  		case TC_ACT_QUEUED:

  			*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;

  		case TC_ACT_SHOT:
  			return NULL;

  		}

  #endif

  		if (!fl || err < 0) {

  			if (TC_H_MAJ(band))
  				band = 0;

  			return q->queues[q->prio2band[band & TC_PRIO_MAX]];

  		}
  		band = res.classid;
  	}
  	band = TC_H_MIN(band) - 1;

  	if (band >= q->bands)

  		return q->queues[q->prio2band[0]];

  	return q->queues[band];
  }
  
  static int

  prio_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)

  {
  	struct Qdisc *qdisc;
  	int ret;
  
  	qdisc = prio_classify(skb, sch, &ret);
  #ifdef CONFIG_NET_CLS_ACT
  	if (qdisc == NULL) {

  		if (ret & __NET_XMIT_BYPASS)

  			qdisc_qstats_drop(sch);

  		kfree_skb(skb);
  		return ret;
  	}
  #endif

  	ret = qdisc_enqueue(skb, qdisc, to_free);

  	if (ret == NET_XMIT_SUCCESS) {

  		qdisc_qstats_backlog_inc(sch, skb);

  		sch->q.qlen++;
  		return NET_XMIT_SUCCESS;
  	}

  	if (net_xmit_drop_count(ret))

  		qdisc_qstats_drop(sch);

  	return ret;

  }

  static struct sk_buff *prio_peek(struct Qdisc *sch)
  {
  	struct prio_sched_data *q = qdisc_priv(sch);
  	int prio;
  
  	for (prio = 0; prio < q->bands; prio++) {
  		struct Qdisc *qdisc = q->queues[prio];
  		struct sk_buff *skb = qdisc->ops->peek(qdisc);
  		if (skb)
  			return skb;
  	}
  	return NULL;
  }

  static struct sk_buff *prio_dequeue(struct Qdisc *sch)

  {

  	struct prio_sched_data *q = qdisc_priv(sch);
  	int prio;

  
  	for (prio = 0; prio < q->bands; prio++) {

  		struct Qdisc *qdisc = q->queues[prio];

  		struct sk_buff *skb = qdisc_dequeue_peeked(qdisc);

  		if (skb) {

  			qdisc_bstats_update(sch, skb);

  			qdisc_qstats_backlog_dec(sch, skb);

  			sch->q.qlen--;
  			return skb;

  		}
  	}
  	return NULL;
  
  }

  static void

  prio_reset(struct Qdisc *sch)

  {
  	int prio;
  	struct prio_sched_data *q = qdisc_priv(sch);

  	for (prio = 0; prio < q->bands; prio++)

  		qdisc_reset(q->queues[prio]);

  	sch->qstats.backlog = 0;

  	sch->q.qlen = 0;
  }
  
  static void

  prio_destroy(struct Qdisc *sch)

  {
  	int prio;
  	struct prio_sched_data *q = qdisc_priv(sch);

  	tcf_destroy_chain(&q->filter_list);

  	for (prio = 0; prio < q->bands; prio++)

  		qdisc_destroy(q->queues[prio]);
  }

  static int prio_tune(struct Qdisc *sch, struct nlattr *opt)

  {
  	struct prio_sched_data *q = qdisc_priv(sch);

  	struct Qdisc *queues[TCQ_PRIO_BANDS];
  	int oldbands = q->bands, i;

  	struct tc_prio_qopt *qopt;

  	if (nla_len(opt) < sizeof(*qopt))
  		return -EINVAL;
  	qopt = nla_data(opt);

  	if (qopt->bands > TCQ_PRIO_BANDS || qopt->bands < 2)

  		return -EINVAL;

  	for (i = 0; i <= TC_PRIO_MAX; i++) {

  		if (qopt->priomap[i] >= qopt->bands)

  			return -EINVAL;
  	}

  	/* Before commit, make sure we can allocate all new qdiscs */
  	for (i = oldbands; i < qopt->bands; i++) {
  		queues[i] = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
  					      TC_H_MAKE(sch->handle, i + 1));
  		if (!queues[i]) {
  			while (i > oldbands)
  				qdisc_destroy(queues[--i]);
  			return -ENOMEM;
  		}
  	}

  	sch_tree_lock(sch);

  	q->bands = qopt->bands;

  	memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);

  	for (i = q->bands; i < oldbands; i++) {

  		struct Qdisc *child = q->queues[i];

  		qdisc_tree_reduce_backlog(child, child->q.qlen,
  					  child->qstats.backlog);
  		qdisc_destroy(child);

  	}

  	for (i = oldbands; i < q->bands; i++)
  		q->queues[i] = queues[i];

  	sch_tree_unlock(sch);

  	return 0;
  }

  static int prio_init(struct Qdisc *sch, struct nlattr *opt)

  {

  	if (!opt)

  		return -EINVAL;

  	return prio_tune(sch, opt);

  }
  
  static int prio_dump(struct Qdisc *sch, struct sk_buff *skb)
  {
  	struct prio_sched_data *q = qdisc_priv(sch);

  	unsigned char *b = skb_tail_pointer(skb);

  	struct tc_prio_qopt opt;
  
  	opt.bands = q->bands;

  	memcpy(&opt.priomap, q->prio2band, TC_PRIO_MAX + 1);

  	if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
  		goto nla_put_failure;

  	return skb->len;

  nla_put_failure:

  	nlmsg_trim(skb, b);

  	return -1;
  }
  
  static int prio_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
  		      struct Qdisc **old)
  {
  	struct prio_sched_data *q = qdisc_priv(sch);
  	unsigned long band = arg - 1;

  	if (new == NULL)
  		new = &noop_qdisc;

  	*old = qdisc_replace(sch, new, &q->queues[band]);

  	return 0;
  }
  
  static struct Qdisc *
  prio_leaf(struct Qdisc *sch, unsigned long arg)
  {
  	struct prio_sched_data *q = qdisc_priv(sch);
  	unsigned long band = arg - 1;

  	return q->queues[band];
  }
  
  static unsigned long prio_get(struct Qdisc *sch, u32 classid)
  {
  	struct prio_sched_data *q = qdisc_priv(sch);
  	unsigned long band = TC_H_MIN(classid);
  
  	if (band - 1 >= q->bands)
  		return 0;
  	return band;
  }
  
  static unsigned long prio_bind(struct Qdisc *sch, unsigned long parent, u32 classid)
  {
  	return prio_get(sch, classid);
  }
  
  
  static void prio_put(struct Qdisc *q, unsigned long cl)
  {

  }

  static int prio_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *skb,
  			   struct tcmsg *tcm)
  {
  	struct prio_sched_data *q = qdisc_priv(sch);

  	tcm->tcm_handle |= TC_H_MIN(cl);

  	tcm->tcm_info = q->queues[cl-1]->handle;

  	return 0;
  }

  static int prio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
  				 struct gnet_dump *d)
  {
  	struct prio_sched_data *q = qdisc_priv(sch);
  	struct Qdisc *cl_q;
  
  	cl_q = q->queues[cl - 1];

  	if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
  				  d, NULL, &cl_q->bstats) < 0 ||

  	    gnet_stats_copy_queue(d, NULL, &cl_q->qstats, cl_q->q.qlen) < 0)

  		return -1;
  
  	return 0;
  }

  static void prio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
  {
  	struct prio_sched_data *q = qdisc_priv(sch);
  	int prio;
  
  	if (arg->stop)
  		return;
  
  	for (prio = 0; prio < q->bands; prio++) {
  		if (arg->count < arg->skip) {
  			arg->count++;
  			continue;
  		}

  		if (arg->fn(sch, prio + 1, arg) < 0) {

  			arg->stop = 1;
  			break;
  		}
  		arg->count++;
  	}
  }

  static struct tcf_proto __rcu **prio_find_tcf(struct Qdisc *sch,
  					      unsigned long cl)

  {
  	struct prio_sched_data *q = qdisc_priv(sch);
  
  	if (cl)
  		return NULL;
  	return &q->filter_list;
  }

  static const struct Qdisc_class_ops prio_class_ops = {

  	.graft		=	prio_graft,
  	.leaf		=	prio_leaf,
  	.get		=	prio_get,
  	.put		=	prio_put,

  	.walk		=	prio_walk,
  	.tcf_chain	=	prio_find_tcf,
  	.bind_tcf	=	prio_bind,
  	.unbind_tcf	=	prio_put,
  	.dump		=	prio_dump_class,

  	.dump_stats	=	prio_dump_class_stats,

  };

  static struct Qdisc_ops prio_qdisc_ops __read_mostly = {

  	.next		=	NULL,
  	.cl_ops		=	&prio_class_ops,
  	.id		=	"prio",
  	.priv_size	=	sizeof(struct prio_sched_data),
  	.enqueue	=	prio_enqueue,
  	.dequeue	=	prio_dequeue,

  	.peek		=	prio_peek,

  	.init		=	prio_init,
  	.reset		=	prio_reset,
  	.destroy	=	prio_destroy,
  	.change		=	prio_tune,
  	.dump		=	prio_dump,
  	.owner		=	THIS_MODULE,
  };
  
  static int __init prio_module_init(void)
  {

  	return register_qdisc(&prio_qdisc_ops);

  }

  static void __exit prio_module_exit(void)

  {
  	unregister_qdisc(&prio_qdisc_ops);
  }
  
  module_init(prio_module_init)
  module_exit(prio_module_exit)
  
  MODULE_LICENSE("GPL");