/*
   * net/sched/sch_mqprio.c
   *
   * Copyright (c) 2010 John Fastabend <john.r.fastabend@intel.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * version 2 as published by the Free Software Foundation.
   */
  
  #include <linux/types.h>
  #include <linux/slab.h>
  #include <linux/kernel.h>
  #include <linux/string.h>
  #include <linux/errno.h>
  #include <linux/skbuff.h>
  #include <linux/module.h>
  #include <net/netlink.h>
  #include <net/pkt_sched.h>
  #include <net/sch_generic.h>
  
  struct mqprio_sched {
  	struct Qdisc		**qdiscs;
  	int hw_owned;
  };
  
  static void mqprio_destroy(struct Qdisc *sch)
  {
  	struct net_device *dev = qdisc_dev(sch);
  	struct mqprio_sched *priv = qdisc_priv(sch);
  	unsigned int ntx;
  
  	if (priv->qdiscs) {
  		for (ntx = 0;
  		     ntx < dev->num_tx_queues && priv->qdiscs[ntx];
  		     ntx++)
  			qdisc_destroy(priv->qdiscs[ntx]);
  		kfree(priv->qdiscs);
  	}
  
  	if (priv->hw_owned && dev->netdev_ops->ndo_setup_tc)
  		dev->netdev_ops->ndo_setup_tc(dev, 0);
  	else
  		netdev_set_num_tc(dev, 0);
  }
  
  static int mqprio_parse_opt(struct net_device *dev, struct tc_mqprio_qopt *qopt)
  {
  	int i, j;
  
  	/* Verify num_tc is not out of max range */
  	if (qopt->num_tc > TC_MAX_QUEUE)
  		return -EINVAL;
  
  	/* Verify priority mapping uses valid tcs */
  	for (i = 0; i < TC_BITMASK + 1; i++) {
  		if (qopt->prio_tc_map[i] >= qopt->num_tc)
  			return -EINVAL;
  	}
  
  	/* net_device does not support requested operation */
  	if (qopt->hw && !dev->netdev_ops->ndo_setup_tc)
  		return -EINVAL;
  
  	/* if hw owned qcount and qoffset are taken from LLD so
  	 * no reason to verify them here
  	 */
  	if (qopt->hw)
  		return 0;
  
  	for (i = 0; i < qopt->num_tc; i++) {
  		unsigned int last = qopt->offset[i] + qopt->count[i];
  
  		/* Verify the queue count is in tx range being equal to the
  		 * real_num_tx_queues indicates the last queue is in use.
  		 */
  		if (qopt->offset[i] >= dev->real_num_tx_queues ||
  		    !qopt->count[i] ||
  		    last > dev->real_num_tx_queues)
  			return -EINVAL;
  
  		/* Verify that the offset and counts do not overlap */
  		for (j = i + 1; j < qopt->num_tc; j++) {
  			if (last > qopt->offset[j])
  				return -EINVAL;
  		}
  	}
  
  	return 0;
  }
  
  static int mqprio_init(struct Qdisc *sch, struct nlattr *opt)
  {
  	struct net_device *dev = qdisc_dev(sch);
  	struct mqprio_sched *priv = qdisc_priv(sch);
  	struct netdev_queue *dev_queue;
  	struct Qdisc *qdisc;
  	int i, err = -EOPNOTSUPP;
  	struct tc_mqprio_qopt *qopt = NULL;
  
  	BUILD_BUG_ON(TC_MAX_QUEUE != TC_QOPT_MAX_QUEUE);
  	BUILD_BUG_ON(TC_BITMASK != TC_QOPT_BITMASK);
  
  	if (sch->parent != TC_H_ROOT)
  		return -EOPNOTSUPP;
  
  	if (!netif_is_multiqueue(dev))
  		return -EOPNOTSUPP;
  
  	if (!opt || nla_len(opt) < sizeof(*qopt))
  		return -EINVAL;
  
  	qopt = nla_data(opt);
  	if (mqprio_parse_opt(dev, qopt))
  		return -EINVAL;
  
  	/* pre-allocate qdisc, attachment can't fail */
  	priv->qdiscs = kcalloc(dev->num_tx_queues, sizeof(priv->qdiscs[0]),
  			       GFP_KERNEL);
  	if (priv->qdiscs == NULL) {
  		err = -ENOMEM;
  		goto err;
  	}
  
  	for (i = 0; i < dev->num_tx_queues; i++) {
  		dev_queue = netdev_get_tx_queue(dev, i);
  		qdisc = qdisc_create_dflt(dev_queue, default_qdisc_ops,
  					  TC_H_MAKE(TC_H_MAJ(sch->handle),
  						    TC_H_MIN(i + 1)));
  		if (qdisc == NULL) {
  			err = -ENOMEM;
  			goto err;
  		}
  		priv->qdiscs[i] = qdisc;
  		qdisc->flags |= TCQ_F_ONETXQUEUE;
  	}
  
  	/* If the mqprio options indicate that hardware should own
  	 * the queue mapping then run ndo_setup_tc otherwise use the
  	 * supplied and verified mapping
  	 */
  	if (qopt->hw) {
  		priv->hw_owned = 1;
  		err = dev->netdev_ops->ndo_setup_tc(dev, qopt->num_tc);
  		if (err)
  			goto err;
  	} else {
  		netdev_set_num_tc(dev, qopt->num_tc);
  		for (i = 0; i < qopt->num_tc; i++)
  			netdev_set_tc_queue(dev, i,
  					    qopt->count[i], qopt->offset[i]);
  	}
  
  	/* Always use supplied priority mappings */
  	for (i = 0; i < TC_BITMASK + 1; i++)
  		netdev_set_prio_tc_map(dev, i, qopt->prio_tc_map[i]);
  
  	sch->flags |= TCQ_F_MQROOT;
  	return 0;
  
  err:
  	mqprio_destroy(sch);
  	return err;
  }
  
  static void mqprio_attach(struct Qdisc *sch)
  {
  	struct net_device *dev = qdisc_dev(sch);
  	struct mqprio_sched *priv = qdisc_priv(sch);
  	struct Qdisc *qdisc, *old;
  	unsigned int ntx;
  
  	/* Attach underlying qdisc */
  	for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
  		qdisc = priv->qdiscs[ntx];
  		old = dev_graft_qdisc(qdisc->dev_queue, qdisc);
  		if (old)
  			qdisc_destroy(old);
  		if (ntx < dev->real_num_tx_queues)
  			qdisc_list_add(qdisc);
  	}
  	kfree(priv->qdiscs);
  	priv->qdiscs = NULL;
  }
  
  static struct netdev_queue *mqprio_queue_get(struct Qdisc *sch,
  					     unsigned long cl)
  {
  	struct net_device *dev = qdisc_dev(sch);
  	unsigned long ntx = cl - 1 - netdev_get_num_tc(dev);
  
  	if (ntx >= dev->num_tx_queues)
  		return NULL;
  	return netdev_get_tx_queue(dev, ntx);
  }
  
  static int mqprio_graft(struct Qdisc *sch, unsigned long cl, struct Qdisc *new,
  		    struct Qdisc **old)
  {
  	struct net_device *dev = qdisc_dev(sch);
  	struct netdev_queue *dev_queue = mqprio_queue_get(sch, cl);
  
  	if (!dev_queue)
  		return -EINVAL;
  
  	if (dev->flags & IFF_UP)
  		dev_deactivate(dev);
  
  	*old = dev_graft_qdisc(dev_queue, new);
  
  	if (new)
  		new->flags |= TCQ_F_ONETXQUEUE;
  
  	if (dev->flags & IFF_UP)
  		dev_activate(dev);
  
  	return 0;
  }
  
  static int mqprio_dump(struct Qdisc *sch, struct sk_buff *skb)
  {
  	struct net_device *dev = qdisc_dev(sch);
  	struct mqprio_sched *priv = qdisc_priv(sch);
  	unsigned char *b = skb_tail_pointer(skb);
  	struct tc_mqprio_qopt opt = { 0 };
  	struct Qdisc *qdisc;
  	unsigned int i;
  
  	sch->q.qlen = 0;
  	memset(&sch->bstats, 0, sizeof(sch->bstats));
  	memset(&sch->qstats, 0, sizeof(sch->qstats));
  
  	for (i = 0; i < dev->num_tx_queues; i++) {
  		qdisc = netdev_get_tx_queue(dev, i)->qdisc;
  		spin_lock_bh(qdisc_lock(qdisc));
  		sch->q.qlen		+= qdisc->q.qlen;
  		sch->bstats.bytes	+= qdisc->bstats.bytes;
  		sch->bstats.packets	+= qdisc->bstats.packets;
  		sch->qstats.qlen	+= qdisc->qstats.qlen;
  		sch->qstats.backlog	+= qdisc->qstats.backlog;
  		sch->qstats.drops	+= qdisc->qstats.drops;
  		sch->qstats.requeues	+= qdisc->qstats.requeues;
  		sch->qstats.overlimits	+= qdisc->qstats.overlimits;
  		spin_unlock_bh(qdisc_lock(qdisc));
  	}
  
  	opt.num_tc = netdev_get_num_tc(dev);
  	memcpy(opt.prio_tc_map, dev->prio_tc_map, sizeof(opt.prio_tc_map));
  	opt.hw = priv->hw_owned;
  
  	for (i = 0; i < netdev_get_num_tc(dev); i++) {
  		opt.count[i] = dev->tc_to_txq[i].count;
  		opt.offset[i] = dev->tc_to_txq[i].offset;
  	}
  
  	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 struct Qdisc *mqprio_leaf(struct Qdisc *sch, unsigned long cl)
  {
  	struct netdev_queue *dev_queue = mqprio_queue_get(sch, cl);
  
  	if (!dev_queue)
  		return NULL;
  
  	return dev_queue->qdisc_sleeping;
  }
  
  static unsigned long mqprio_get(struct Qdisc *sch, u32 classid)
  {
  	struct net_device *dev = qdisc_dev(sch);
  	unsigned int ntx = TC_H_MIN(classid);
  
  	if (ntx > dev->num_tx_queues + netdev_get_num_tc(dev))
  		return 0;
  	return ntx;
  }
  
  static void mqprio_put(struct Qdisc *sch, unsigned long cl)
  {
  }
  
  static int mqprio_dump_class(struct Qdisc *sch, unsigned long cl,
  			 struct sk_buff *skb, struct tcmsg *tcm)
  {
  	struct net_device *dev = qdisc_dev(sch);
  
  	if (cl <= netdev_get_num_tc(dev)) {
  		tcm->tcm_parent = TC_H_ROOT;
  		tcm->tcm_info = 0;
  	} else {
  		int i;
  		struct netdev_queue *dev_queue;
  
  		dev_queue = mqprio_queue_get(sch, cl);
  		tcm->tcm_parent = 0;
  		for (i = 0; i < netdev_get_num_tc(dev); i++) {
  			struct netdev_tc_txq tc = dev->tc_to_txq[i];
  			int q_idx = cl - netdev_get_num_tc(dev);
  
  			if (q_idx > tc.offset &&
  			    q_idx <= tc.offset + tc.count) {
  				tcm->tcm_parent =
  					TC_H_MAKE(TC_H_MAJ(sch->handle),
  						  TC_H_MIN(i + 1));
  				break;
  			}
  		}
  		tcm->tcm_info = dev_queue->qdisc_sleeping->handle;
  	}
  	tcm->tcm_handle |= TC_H_MIN(cl);
  	return 0;
  }
  
  static int mqprio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
  				   struct gnet_dump *d)
  	__releases(d->lock)
  	__acquires(d->lock)
  {
  	struct net_device *dev = qdisc_dev(sch);
  
  	if (cl <= netdev_get_num_tc(dev)) {
  		int i;
  		struct Qdisc *qdisc;
  		struct gnet_stats_queue qstats = {0};
  		struct gnet_stats_basic_packed bstats = {0};
  		struct netdev_tc_txq tc = dev->tc_to_txq[cl - 1];
  
  		/* Drop lock here it will be reclaimed before touching
  		 * statistics this is required because the d->lock we
  		 * hold here is the look on dev_queue->qdisc_sleeping
  		 * also acquired below.
  		 */
  		spin_unlock_bh(d->lock);
  
  		for (i = tc.offset; i < tc.offset + tc.count; i++) {
  			qdisc = netdev_get_tx_queue(dev, i)->qdisc;
  			spin_lock_bh(qdisc_lock(qdisc));
  			bstats.bytes      += qdisc->bstats.bytes;
  			bstats.packets    += qdisc->bstats.packets;
  			qstats.qlen       += qdisc->qstats.qlen;
  			qstats.backlog    += qdisc->qstats.backlog;
  			qstats.drops      += qdisc->qstats.drops;
  			qstats.requeues   += qdisc->qstats.requeues;
  			qstats.overlimits += qdisc->qstats.overlimits;
  			spin_unlock_bh(qdisc_lock(qdisc));
  		}
  		/* Reclaim root sleeping lock before completing stats */
  		spin_lock_bh(d->lock);
  		if (gnet_stats_copy_basic(d, &bstats) < 0 ||
  		    gnet_stats_copy_queue(d, &qstats) < 0)
  			return -1;
  	} else {
  		struct netdev_queue *dev_queue = mqprio_queue_get(sch, cl);
  
  		sch = dev_queue->qdisc_sleeping;
  		sch->qstats.qlen = sch->q.qlen;
  		if (gnet_stats_copy_basic(d, &sch->bstats) < 0 ||
  		    gnet_stats_copy_queue(d, &sch->qstats) < 0)
  			return -1;
  	}
  	return 0;
  }
  
  static void mqprio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
  {
  	struct net_device *dev = qdisc_dev(sch);
  	unsigned long ntx;
  
  	if (arg->stop)
  		return;
  
  	/* Walk hierarchy with a virtual class per tc */
  	arg->count = arg->skip;
  	for (ntx = arg->skip;
  	     ntx < dev->num_tx_queues + netdev_get_num_tc(dev);
  	     ntx++) {
  		if (arg->fn(sch, ntx + 1, arg) < 0) {
  			arg->stop = 1;
  			break;
  		}
  		arg->count++;
  	}
  }
  
  static const struct Qdisc_class_ops mqprio_class_ops = {
  	.graft		= mqprio_graft,
  	.leaf		= mqprio_leaf,
  	.get		= mqprio_get,
  	.put		= mqprio_put,
  	.walk		= mqprio_walk,
  	.dump		= mqprio_dump_class,
  	.dump_stats	= mqprio_dump_class_stats,
  };
  
  static struct Qdisc_ops mqprio_qdisc_ops __read_mostly = {
  	.cl_ops		= &mqprio_class_ops,
  	.id		= "mqprio",
  	.priv_size	= sizeof(struct mqprio_sched),
  	.init		= mqprio_init,
  	.destroy	= mqprio_destroy,
  	.attach		= mqprio_attach,
  	.dump		= mqprio_dump,
  	.owner		= THIS_MODULE,
  };
  
  static int __init mqprio_module_init(void)
  {
  	return register_qdisc(&mqprio_qdisc_ops);
  }
  
  static void __exit mqprio_module_exit(void)
  {
  	unregister_qdisc(&mqprio_qdisc_ops);
  }
  
  module_init(mqprio_module_init);
  module_exit(mqprio_module_exit);
  
  MODULE_LICENSE("GPL");