/*
 * 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, &pfifo_fast_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;
        }

        /* 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;
        unsigned int ntx;

        /* Attach underlying qdisc */
        for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
                qdisc = priv->qdiscs[ntx];
                qdisc = dev_graft_qdisc(qdisc->dev_queue, qdisc);
                if (qdisc)
                        qdisc_destroy(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 (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;
        }

        NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);

        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");