// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * net/sched/sch_generic.c      Generic packet scheduler routines.
 *
 * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *              Jamal Hadi Salim, <hadi@cyberus.ca> 990601
 *              - Ingress support
 */

#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/init.h>
#include <linux/rcupdate.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/if_vlan.h>
#include <linux/skb_array.h>
#include <linux/if_macvlan.h>
#include <net/sch_generic.h>
#include <net/pkt_sched.h>
#include <net/dst.h>
#include <trace/events/qdisc.h>
#include <trace/events/net.h>
#include <net/xfrm.h>

/* Qdisc to use by default */
const struct Qdisc_ops *default_qdisc_ops = &pfifo_fast_ops;
EXPORT_SYMBOL(default_qdisc_ops);

/* Main transmission queue. */

/* Modifications to data participating in scheduling must be protected with
 * qdisc_lock(qdisc) spinlock.
 *
 * The idea is the following:
 * - enqueue, dequeue are serialized via qdisc root lock
 * - ingress filtering is also serialized via qdisc root lock
 * - updates to tree and tree walking are only done under the rtnl mutex.
 */

#define SKB_XOFF_MAGIC ((struct sk_buff *)1UL)

static inline struct sk_buff *__skb_dequeue_bad_txq(struct Qdisc *q)
{
        const struct netdev_queue *txq = q->dev_queue;
        spinlock_t *lock = NULL;
        struct sk_buff *skb;

        if (q->flags & TCQ_F_NOLOCK) {
                lock = qdisc_lock(q);
                spin_lock(lock);
        }

        skb = skb_peek(&q->skb_bad_txq);
        if (skb) {
                /* check the reason of requeuing without tx lock first */
                txq = skb_get_tx_queue(txq->dev, skb);
                if (!netif_xmit_frozen_or_stopped(txq)) {
                        skb = __skb_dequeue(&q->skb_bad_txq);
                        if (qdisc_is_percpu_stats(q)) {
                                qdisc_qstats_cpu_backlog_dec(q, skb);
                                qdisc_qstats_cpu_qlen_dec(q);
                        } else {
                                qdisc_qstats_backlog_dec(q, skb);
                                q->q.qlen--;
                        }
                } else {
                        skb = SKB_XOFF_MAGIC;
                }
        }

        if (lock)
                spin_unlock(lock);

        return skb;
}

static inline struct sk_buff *qdisc_dequeue_skb_bad_txq(struct Qdisc *q)
{
        struct sk_buff *skb = skb_peek(&q->skb_bad_txq);

        if (unlikely(skb))
                skb = __skb_dequeue_bad_txq(q);

        return skb;
}

static inline void qdisc_enqueue_skb_bad_txq(struct Qdisc *q,
                                             struct sk_buff *skb)
{
        spinlock_t *lock = NULL;

        if (q->flags & TCQ_F_NOLOCK) {
                lock = qdisc_lock(q);
                spin_lock(lock);
        }

        __skb_queue_tail(&q->skb_bad_txq, skb);

        if (qdisc_is_percpu_stats(q)) {
                qdisc_qstats_cpu_backlog_inc(q, skb);
                qdisc_qstats_cpu_qlen_inc(q);
        } else {
                qdisc_qstats_backlog_inc(q, skb);
                q->q.qlen++;
        }

        if (lock)
                spin_unlock(lock);
}

static inline void dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
{
        spinlock_t *lock = NULL;

        if (q->flags & TCQ_F_NOLOCK) {
                lock = qdisc_lock(q);
                spin_lock(lock);
        }

        while (skb) {
                struct sk_buff *next = skb->next;

                __skb_queue_tail(&q->gso_skb, skb);

                /* it's still part of the queue */
                if (qdisc_is_percpu_stats(q)) {
                        qdisc_qstats_cpu_requeues_inc(q);
                        qdisc_qstats_cpu_backlog_inc(q, skb);
                        qdisc_qstats_cpu_qlen_inc(q);
                } else {
                        q->qstats.requeues++;
                        qdisc_qstats_backlog_inc(q, skb);
                        q->q.qlen++;
                }

                skb = next;
        }
        if (lock)
                spin_unlock(lock);
        __netif_schedule(q);
}

static void try_bulk_dequeue_skb(struct Qdisc *q,
                                 struct sk_buff *skb,
                                 const struct netdev_queue *txq,
                                 int *packets)
{
        int bytelimit = qdisc_avail_bulklimit(txq) - skb->len;

        while (bytelimit > 0) {
                struct sk_buff *nskb = q->dequeue(q);

                if (!nskb)
                        break;

                bytelimit -= nskb->len; /* covers GSO len */
                skb->next = nskb;
                skb = nskb;
                (*packets)++; /* GSO counts as one pkt */
        }
        skb_mark_not_on_list(skb);
}

/* This variant of try_bulk_dequeue_skb() makes sure
 * all skbs in the chain are for the same txq
 */
static void try_bulk_dequeue_skb_slow(struct Qdisc *q,
                                      struct sk_buff *skb,
                                      int *packets)
{
        int mapping = skb_get_queue_mapping(skb);
        struct sk_buff *nskb;
        int cnt = 0;

        do {
                nskb = q->dequeue(q);
                if (!nskb)
                        break;
                if (unlikely(skb_get_queue_mapping(nskb) != mapping)) {
                        qdisc_enqueue_skb_bad_txq(q, nskb);
                        break;
                }
                skb->next = nskb;
                skb = nskb;
        } while (++cnt < 8);
        (*packets) += cnt;
        skb_mark_not_on_list(skb);
}

/* Note that dequeue_skb can possibly return a SKB list (via skb->next).
 * A requeued skb (via q->gso_skb) can also be a SKB list.
 */
static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
                                   int *packets)
{
        const struct netdev_queue *txq = q->dev_queue;
        struct sk_buff *skb = NULL;

        *packets = 1;
        if (unlikely(!skb_queue_empty(&q->gso_skb))) {
                spinlock_t *lock = NULL;

                if (q->flags & TCQ_F_NOLOCK) {
                        lock = qdisc_lock(q);
                        spin_lock(lock);
                }

                skb = skb_peek(&q->gso_skb);

                /* skb may be null if another cpu pulls gso_skb off in between
                 * empty check and lock.
                 */
                if (!skb) {
                        if (lock)
                                spin_unlock(lock);
                        goto validate;
                }

                /* skb in gso_skb were already validated */
                *validate = false;
                if (xfrm_offload(skb))
                        *validate = true;
                /* check the reason of requeuing without tx lock first */
                txq = skb_get_tx_queue(txq->dev, skb);
                if (!netif_xmit_frozen_or_stopped(txq)) {
                        skb = __skb_dequeue(&q->gso_skb);
                        if (qdisc_is_percpu_stats(q)) {
                                qdisc_qstats_cpu_backlog_dec(q, skb);
                                qdisc_qstats_cpu_qlen_dec(q);
                        } else {
                                qdisc_qstats_backlog_dec(q, skb);
                                q->q.qlen--;
                        }
                } else {
                        skb = NULL;
                }
                if (lock)
                        spin_unlock(lock);
                goto trace;
        }
validate:
        *validate = true;

        if ((q->flags & TCQ_F_ONETXQUEUE) &&
            netif_xmit_frozen_or_stopped(txq))
                return skb;

        skb = qdisc_dequeue_skb_bad_txq(q);
        if (unlikely(skb)) {
                if (skb == SKB_XOFF_MAGIC)
                        return NULL;
                goto bulk;
        }
        skb = q->dequeue(q);
        if (skb) {
bulk:
                if (qdisc_may_bulk(q))
                        try_bulk_dequeue_skb(q, skb, txq, packets);
                else
                        try_bulk_dequeue_skb_slow(q, skb, packets);
        }
trace:
        trace_qdisc_dequeue(q, txq, *packets, skb);
        return skb;
}

/*
 * Transmit possibly several skbs, and handle the return status as
 * required. Owning running seqcount bit guarantees that
 * only one CPU can execute this function.
 *
 * Returns to the caller:
 *                              false  - hardware queue frozen backoff
 *                              true   - feel free to send more pkts
 */
bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
                     struct net_device *dev, struct netdev_queue *txq,
                     spinlock_t *root_lock, bool validate)
{
        int ret = NETDEV_TX_BUSY;
        bool again = false;

        /* And release qdisc */
        if (root_lock)
                spin_unlock(root_lock);

        /* Note that we validate skb (GSO, checksum, ...) outside of locks */
        if (validate)
                skb = validate_xmit_skb_list(skb, dev, &again);

#ifdef CONFIG_XFRM_OFFLOAD
        if (unlikely(again)) {
                if (root_lock)
                        spin_lock(root_lock);

                dev_requeue_skb(skb, q);
                return false;
        }
#endif

        if (likely(skb)) {
                HARD_TX_LOCK(dev, txq, smp_processor_id());
                if (!netif_xmit_frozen_or_stopped(txq))
                        skb = dev_hard_start_xmit(skb, dev, txq, &ret);

                HARD_TX_UNLOCK(dev, txq);
        } else {
                if (root_lock)
                        spin_lock(root_lock);
                return true;
        }

        if (root_lock)
                spin_lock(root_lock);

        if (!dev_xmit_complete(ret)) {
                /* Driver returned NETDEV_TX_BUSY - requeue skb */
                if (unlikely(ret != NETDEV_TX_BUSY))
                        net_warn_ratelimited("BUG %s code %d qlen %d\n",
                                             dev->name, ret, q->q.qlen);

                dev_requeue_skb(skb, q);
                return false;
        }

        return true;
}

/*
 * NOTE: Called under qdisc_lock(q) with locally disabled BH.
 *
 * running seqcount guarantees only one CPU can process
 * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
 * this queue.
 *
 *  netif_tx_lock serializes accesses to device driver.
 *
 *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
 *  if one is grabbed, another must be free.
 *
 * Note, that this procedure can be called by a watchdog timer
 *
 * Returns to the caller:
 *                              0  - queue is empty or throttled.
 *                              >0 - queue is not empty.
 *
 */
static inline bool qdisc_restart(struct Qdisc *q, int *packets)
{
        spinlock_t *root_lock = NULL;
        struct netdev_queue *txq;
        struct net_device *dev;
        struct sk_buff *skb;
        bool validate;

        /* Dequeue packet */
        skb = dequeue_skb(q, &validate, packets);
        if (unlikely(!skb))
                return false;

        if (!(q->flags & TCQ_F_NOLOCK))
                root_lock = qdisc_lock(q);

        dev = qdisc_dev(q);
        txq = skb_get_tx_queue(dev, skb);

        return sch_direct_xmit(skb, q, dev, txq, root_lock, validate);
}

void __qdisc_run(struct Qdisc *q)
{
        int quota = dev_tx_weight;
        int packets;

        while (qdisc_restart(q, &packets)) {
                quota -= packets;
                if (quota <= 0) {
                        __netif_schedule(q);
                        break;
                }
        }
}

unsigned long dev_trans_start(struct net_device *dev)
{
        unsigned long val, res;
        unsigned int i;

        if (is_vlan_dev(dev))
                dev = vlan_dev_real_dev(dev);
        else if (netif_is_macvlan(dev))
                dev = macvlan_dev_real_dev(dev);
        res = netdev_get_tx_queue(dev, 0)->trans_start;
        for (i = 1; i < dev->num_tx_queues; i++) {
                val = netdev_get_tx_queue(dev, i)->trans_start;
                if (val && time_after(val, res))
                        res = val;
        }

        return res;
}
EXPORT_SYMBOL(dev_trans_start);

static void dev_watchdog(struct timer_list *t)
{
        struct net_device *dev = from_timer(dev, t, watchdog_timer);

        netif_tx_lock(dev);
        if (!qdisc_tx_is_noop(dev)) {
                if (netif_device_present(dev) &&
                    netif_running(dev) &&
                    netif_carrier_ok(dev)) {
                        int some_queue_timedout = 0;
                        unsigned int i;
                        unsigned long trans_start;

                        for (i = 0; i < dev->num_tx_queues; i++) {
                                struct netdev_queue *txq;

                                txq = netdev_get_tx_queue(dev, i);
                                trans_start = txq->trans_start;
                                if (netif_xmit_stopped(txq) &&
                                    time_after(jiffies, (trans_start +
                                                         dev->watchdog_timeo))) {
                                        some_queue_timedout = 1;
                                        txq->trans_timeout++;
                                        break;
                                }
                        }

                        if (some_queue_timedout) {
                                trace_net_dev_xmit_timeout(dev, i);
                                WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
                                       dev->name, netdev_drivername(dev), i);
                                dev->netdev_ops->ndo_tx_timeout(dev, i);
                        }
                        if (!mod_timer(&dev->watchdog_timer,
                                       round_jiffies(jiffies +
                                                     dev->watchdog_timeo)))
                                dev_hold(dev);
                }
        }
        netif_tx_unlock(dev);

        dev_put(dev);
}

void __netdev_watchdog_up(struct net_device *dev)
{
        if (dev->netdev_ops->ndo_tx_timeout) {
                if (dev->watchdog_timeo <= 0)
                        dev->watchdog_timeo = 5*HZ;
                if (!mod_timer(&dev->watchdog_timer,
                               round_jiffies(jiffies + dev->watchdog_timeo)))
                        dev_hold(dev);
        }
}
EXPORT_SYMBOL_GPL(__netdev_watchdog_up);

static void dev_watchdog_up(struct net_device *dev)
{
        __netdev_watchdog_up(dev);
}

static void dev_watchdog_down(struct net_device *dev)
{
        netif_tx_lock_bh(dev);
        if (del_timer(&dev->watchdog_timer))
                dev_put(dev);
        netif_tx_unlock_bh(dev);
}

/**
 *      netif_carrier_on - set carrier
 *      @dev: network device
 *
 * Device has detected acquisition of carrier.
 */
void netif_carrier_on(struct net_device *dev)
{
        if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
                if (dev->reg_state == NETREG_UNINITIALIZED)
                        return;
                atomic_inc(&dev->carrier_up_count);
                linkwatch_fire_event(dev);
                if (netif_running(dev))
                        __netdev_watchdog_up(dev);
        }
}
EXPORT_SYMBOL(netif_carrier_on);

/**
 *      netif_carrier_off - clear carrier
 *      @dev: network device
 *
 * Device has detected loss of carrier.
 */
void netif_carrier_off(struct net_device *dev)
{
        if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
                if (dev->reg_state == NETREG_UNINITIALIZED)
                        return;
                atomic_inc(&dev->carrier_down_count);
                linkwatch_fire_event(dev);
        }
}
EXPORT_SYMBOL(netif_carrier_off);

/* "NOOP" scheduler: the best scheduler, recommended for all interfaces
   under all circumstances. It is difficult to invent anything faster or
   cheaper.
 */

static int noop_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
                        struct sk_buff **to_free)
{
        __qdisc_drop(skb, to_free);
        return NET_XMIT_CN;
}

static struct sk_buff *noop_dequeue(struct Qdisc *qdisc)
{
        return NULL;
}

struct Qdisc_ops noop_qdisc_ops __read_mostly = {
        .id             =       "noop",
        .priv_size      =       0,
        .enqueue        =       noop_enqueue,
        .dequeue        =       noop_dequeue,
        .peek           =       noop_dequeue,
        .owner          =       THIS_MODULE,
};

static struct netdev_queue noop_netdev_queue = {
        RCU_POINTER_INITIALIZER(qdisc, &noop_qdisc),
        .qdisc_sleeping =       &noop_qdisc,
};

struct Qdisc noop_qdisc = {
        .enqueue        =       noop_enqueue,
        .dequeue        =       noop_dequeue,
        .flags          =       TCQ_F_BUILTIN,
        .ops            =       &noop_qdisc_ops,
        .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
        .dev_queue      =       &noop_netdev_queue,
        .running        =       SEQCNT_ZERO(noop_qdisc.running),
        .busylock       =       __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
        .gso_skb = {
                .next = (struct sk_buff *)&noop_qdisc.gso_skb,
                .prev = (struct sk_buff *)&noop_qdisc.gso_skb,
                .qlen = 0,
                .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.gso_skb.lock),
        },
        .skb_bad_txq = {
                .next = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
                .prev = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
                .qlen = 0,
                .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.skb_bad_txq.lock),
        },
};
EXPORT_SYMBOL(noop_qdisc);

static int noqueue_init(struct Qdisc *qdisc, struct nlattr *opt,
                        struct netlink_ext_ack *extack)
{
        /* register_qdisc() assigns a default of noop_enqueue if unset,
         * but __dev_queue_xmit() treats noqueue only as such
         * if this is NULL - so clear it here. */
        qdisc->enqueue = NULL;
        return 0;
}

struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
        .id             =       "noqueue",
        .priv_size      =       0,
        .init           =       noqueue_init,
        .enqueue        =       noop_enqueue,
        .dequeue        =       noop_dequeue,
        .peek           =       noop_dequeue,
        .owner          =       THIS_MODULE,
};

static const u8 prio2band[TC_PRIO_MAX + 1] = {
        1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
};

/* 3-band FIFO queue: old style, but should be a bit faster than
   generic prio+fifo combination.
 */

#define PFIFO_FAST_BANDS 3

/*
 * Private data for a pfifo_fast scheduler containing:
 *      - rings for priority bands
 */
struct pfifo_fast_priv {
        struct skb_array q[PFIFO_FAST_BANDS];
};

static inline struct skb_array *band2list(struct pfifo_fast_priv *priv,
                                          int band)
{
        return &priv->q[band];
}

static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
                              struct sk_buff **to_free)
{
        int band = prio2band[skb->priority & TC_PRIO_MAX];
        struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
        struct skb_array *q = band2list(priv, band);
        unsigned int pkt_len = qdisc_pkt_len(skb);
        int err;

        err = skb_array_produce(q, skb);

        if (unlikely(err)) {
                if (qdisc_is_percpu_stats(qdisc))
                        return qdisc_drop_cpu(skb, qdisc, to_free);
                else
                        return qdisc_drop(skb, qdisc, to_free);
        }

        qdisc_update_stats_at_enqueue(qdisc, pkt_len);
        return NET_XMIT_SUCCESS;
}

static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
{
        struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
        struct sk_buff *skb = NULL;
        int band;

        for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
                struct skb_array *q = band2list(priv, band);

                if (__skb_array_empty(q))
                        continue;

                skb = __skb_array_consume(q);
        }
        if (likely(skb)) {
                qdisc_update_stats_at_dequeue(qdisc, skb);
        } else {
                WRITE_ONCE(qdisc->empty, true);
        }

        return skb;
}

static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
{
        struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
        struct sk_buff *skb = NULL;
        int band;

        for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
                struct skb_array *q = band2list(priv, band);

                skb = __skb_array_peek(q);
        }

        return skb;
}

static void pfifo_fast_reset(struct Qdisc *qdisc)
{
        int i, band;
        struct pfifo_fast_priv *priv = qdisc_priv(qdisc);

        for (band = 0; band < PFIFO_FAST_BANDS; band++) {
                struct skb_array *q = band2list(priv, band);
                struct sk_buff *skb;

                /* NULL ring is possible if destroy path is due to a failed
                 * skb_array_init() in pfifo_fast_init() case.
                 */
                if (!q->ring.queue)
                        continue;

                while ((skb = __skb_array_consume(q)) != NULL)
                        kfree_skb(skb);
        }

        if (qdisc_is_percpu_stats(qdisc)) {
                for_each_possible_cpu(i) {
                        struct gnet_stats_queue *q;

                        q = per_cpu_ptr(qdisc->cpu_qstats, i);
                        q->backlog = 0;
                        q->qlen = 0;
                }
        }
}

static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
{
        struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };

        memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
        if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
                goto nla_put_failure;
        return skb->len;

nla_put_failure:
        return -1;
}

static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt,
                           struct netlink_ext_ack *extack)
{
        unsigned int qlen = qdisc_dev(qdisc)->tx_queue_len;
        struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
        int prio;

        /* guard against zero length rings */
        if (!qlen)
                return -EINVAL;

        for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
                struct skb_array *q = band2list(priv, prio);
                int err;

                err = skb_array_init(q, qlen, GFP_KERNEL);
                if (err)
                        return -ENOMEM;
        }

        /* Can by-pass the queue discipline */
        qdisc->flags |= TCQ_F_CAN_BYPASS;
        return 0;
}

static void pfifo_fast_destroy(struct Qdisc *sch)
{
        struct pfifo_fast_priv *priv = qdisc_priv(sch);
        int prio;

        for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
                struct skb_array *q = band2list(priv, prio);

                /* NULL ring is possible if destroy path is due to a failed
                 * skb_array_init() in pfifo_fast_init() case.
                 */
                if (!q->ring.queue)
                        continue;
                /* Destroy ring but no need to kfree_skb because a call to
                 * pfifo_fast_reset() has already done that work.
                 */
                ptr_ring_cleanup(&q->ring, NULL);
        }
}

static int pfifo_fast_change_tx_queue_len(struct Qdisc *sch,
                                          unsigned int new_len)
{
        struct pfifo_fast_priv *priv = qdisc_priv(sch);
        struct skb_array *bands[PFIFO_FAST_BANDS];
        int prio;

        for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
                struct skb_array *q = band2list(priv, prio);

                bands[prio] = q;
        }

        return skb_array_resize_multiple(bands, PFIFO_FAST_BANDS, new_len,
                                         GFP_KERNEL);
}

struct Qdisc_ops pfifo_fast_ops __read_mostly = {
        .id             =       "pfifo_fast",
        .priv_size      =       sizeof(struct pfifo_fast_priv),
        .enqueue        =       pfifo_fast_enqueue,
        .dequeue        =       pfifo_fast_dequeue,
        .peek           =       pfifo_fast_peek,
        .init           =       pfifo_fast_init,
        .destroy        =       pfifo_fast_destroy,
        .reset          =       pfifo_fast_reset,
        .dump           =       pfifo_fast_dump,
        .change_tx_queue_len =  pfifo_fast_change_tx_queue_len,
        .owner          =       THIS_MODULE,
        .static_flags   =       TCQ_F_NOLOCK | TCQ_F_CPUSTATS,
};
EXPORT_SYMBOL(pfifo_fast_ops);

static struct lock_class_key qdisc_tx_busylock;
static struct lock_class_key qdisc_running_key;

struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
                          const struct Qdisc_ops *ops,
                          struct netlink_ext_ack *extack)
{
        void *p;
        struct Qdisc *sch;
        unsigned int size = QDISC_ALIGN(sizeof(*sch)) + ops->priv_size;
        int err = -ENOBUFS;
        struct net_device *dev;

        if (!dev_queue) {
                NL_SET_ERR_MSG(extack, "No device queue given");
                err = -EINVAL;
                goto errout;
        }

        dev = dev_queue->dev;
        p = kzalloc_node(size, GFP_KERNEL,
                         netdev_queue_numa_node_read(dev_queue));

        if (!p)
                goto errout;
        sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
        /* if we got non aligned memory, ask more and do alignment ourself */
        if (sch != p) {
                kfree(p);
                p = kzalloc_node(size + QDISC_ALIGNTO - 1, GFP_KERNEL,
                                 netdev_queue_numa_node_read(dev_queue));
                if (!p)
                        goto errout;
                sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
                sch->padded = (char *) sch - (char *) p;
        }
        __skb_queue_head_init(&sch->gso_skb);
        __skb_queue_head_init(&sch->skb_bad_txq);
        qdisc_skb_head_init(&sch->q);
        spin_lock_init(&sch->q.lock);

        if (ops->static_flags & TCQ_F_CPUSTATS) {
                sch->cpu_bstats =
                        netdev_alloc_pcpu_stats(struct gnet_stats_basic_cpu);
                if (!sch->cpu_bstats)
                        goto errout1;

                sch->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
                if (!sch->cpu_qstats) {
                        free_percpu(sch->cpu_bstats);
                        goto errout1;
                }
        }

        spin_lock_init(&sch->busylock);
        lockdep_set_class(&sch->busylock,
                          dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);

        /* seqlock has the same scope of busylock, for NOLOCK qdisc */
        spin_lock_init(&sch->seqlock);
        lockdep_set_class(&sch->busylock,
                          dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);

        seqcount_init(&sch->running);
        lockdep_set_class(&sch->running,
                          dev->qdisc_running_key ?: &qdisc_running_key);

        sch->ops = ops;
        sch->flags = ops->static_flags;
        sch->enqueue = ops->enqueue;
        sch->dequeue = ops->dequeue;
        sch->dev_queue = dev_queue;
        sch->empty = true;
        dev_hold(dev);
        refcount_set(&sch->refcnt, 1);

        return sch;
errout1:
        kfree(p);
errout:
        return ERR_PTR(err);
}

struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
                                const struct Qdisc_ops *ops,
                                unsigned int parentid,
                                struct netlink_ext_ack *extack)
{
        struct Qdisc *sch;

        if (!try_module_get(ops->owner)) {
                NL_SET_ERR_MSG(extack, "Failed to increase module reference counter");
                return NULL;
        }

        sch = qdisc_alloc(dev_queue, ops, extack);
        if (IS_ERR(sch)) {
                module_put(ops->owner);
                return NULL;
        }
        sch->parent = parentid;

        if (!ops->init || ops->init(sch, NULL, extack) == 0) {
                trace_qdisc_create(ops, dev_queue->dev, parentid);
                return sch;
        }

        qdisc_put(sch);
        return NULL;
}
EXPORT_SYMBOL(qdisc_create_dflt);

/* Under qdisc_lock(qdisc) and BH! */

void qdisc_reset(struct Qdisc *qdisc)
{
        const struct Qdisc_ops *ops = qdisc->ops;
        struct sk_buff *skb, *tmp;

        trace_qdisc_reset(qdisc);

        if (ops->reset)
                ops->reset(qdisc);

        skb_queue_walk_safe(&qdisc->gso_skb, skb, tmp) {
                __skb_unlink(skb, &qdisc->gso_skb);
                kfree_skb_list(skb);
        }

        skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp) {
                __skb_unlink(skb, &qdisc->skb_bad_txq);
                kfree_skb_list(skb);
        }

        qdisc->q.qlen = 0;
        qdisc->qstats.backlog = 0;
}
EXPORT_SYMBOL(qdisc_reset);

void qdisc_free(struct Qdisc *qdisc)
{
        if (qdisc_is_percpu_stats(qdisc)) {
                free_percpu(qdisc->cpu_bstats);
                free_percpu(qdisc->cpu_qstats);
        }

        kfree((char *) qdisc - qdisc->padded);
}

static void qdisc_free_cb(struct rcu_head *head)
{
        struct Qdisc *q = container_of(head, struct Qdisc, rcu);

        qdisc_free(q);
}

static void qdisc_destroy(struct Qdisc *qdisc)
{
        const struct Qdisc_ops  *ops = qdisc->ops;

#ifdef CONFIG_NET_SCHED
        qdisc_hash_del(qdisc);

        qdisc_put_stab(rtnl_dereference(qdisc->stab));
#endif
        gen_kill_estimator(&qdisc->rate_est);

        qdisc_reset(qdisc);

        if (ops->destroy)
                ops->destroy(qdisc);

        module_put(ops->owner);
        dev_put(qdisc_dev(qdisc));

        trace_qdisc_destroy(qdisc);

        call_rcu(&qdisc->rcu, qdisc_free_cb);
}

void qdisc_put(struct Qdisc *qdisc)
{
        if (!qdisc)
                return;

        if (qdisc->flags & TCQ_F_BUILTIN ||
            !refcount_dec_and_test(&qdisc->refcnt))
                return;

        qdisc_destroy(qdisc);
}
EXPORT_SYMBOL(qdisc_put);

/* Version of qdisc_put() that is called with rtnl mutex unlocked.
 * Intended to be used as optimization, this function only takes rtnl lock if
 * qdisc reference counter reached zero.
 */

void qdisc_put_unlocked(struct Qdisc *qdisc)
{
        if (qdisc->flags & TCQ_F_BUILTIN ||
            !refcount_dec_and_rtnl_lock(&qdisc->refcnt))
                return;

        qdisc_destroy(qdisc);
        rtnl_unlock();
}
EXPORT_SYMBOL(qdisc_put_unlocked);

/* Attach toplevel qdisc to device queue. */
struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
                              struct Qdisc *qdisc)
{
        struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
        spinlock_t *root_lock;

        root_lock = qdisc_lock(oqdisc);
        spin_lock_bh(root_lock);

        /* ... and graft new one */
        if (qdisc == NULL)
                qdisc = &noop_qdisc;
        dev_queue->qdisc_sleeping = qdisc;
        rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);

        spin_unlock_bh(root_lock);

        return oqdisc;
}
EXPORT_SYMBOL(dev_graft_qdisc);

static void attach_one_default_qdisc(struct net_device *dev,
                                     struct netdev_queue *dev_queue,
                                     void *_unused)
{
        struct Qdisc *qdisc;
        const struct Qdisc_ops *ops = default_qdisc_ops;

        if (dev->priv_flags & IFF_NO_QUEUE)
                ops = &noqueue_qdisc_ops;
        else if(dev->type == ARPHRD_CAN)
                ops = &pfifo_fast_ops;

        qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT, NULL);
        if (!qdisc)
                return;

        if (!netif_is_multiqueue(dev))
                qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
        dev_queue->qdisc_sleeping = qdisc;
}

static void attach_default_qdiscs(struct net_device *dev)
{
        struct netdev_queue *txq;
        struct Qdisc *qdisc;

        txq = netdev_get_tx_queue(dev, 0);

        if (!netif_is_multiqueue(dev) ||
            dev->priv_flags & IFF_NO_QUEUE) {
                netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
                dev->qdisc = txq->qdisc_sleeping;
                qdisc_refcount_inc(dev->qdisc);
        } else {
                qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT, NULL);
                if (qdisc) {
                        dev->qdisc = qdisc;
                        qdisc->ops->attach(qdisc);
                }
        }

        /* Detect default qdisc setup/init failed and fallback to "noqueue" */
        if (dev->qdisc == &noop_qdisc) {
                netdev_warn(dev, "default qdisc (%s) fail, fallback to %s\n",
                            default_qdisc_ops->id, noqueue_qdisc_ops.id);
                dev->priv_flags |= IFF_NO_QUEUE;
                netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
                dev->qdisc = txq->qdisc_sleeping;
                qdisc_refcount_inc(dev->qdisc);
                dev->priv_flags ^= IFF_NO_QUEUE;
        }

#ifdef CONFIG_NET_SCHED
        if (dev->qdisc != &noop_qdisc)
                qdisc_hash_add(dev->qdisc, false);
#endif
}

static void transition_one_qdisc(struct net_device *dev,
                                 struct netdev_queue *dev_queue,
                                 void *_need_watchdog)
{
        struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
        int *need_watchdog_p = _need_watchdog;

        if (!(new_qdisc->flags & TCQ_F_BUILTIN))
                clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);

        rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
        if (need_watchdog_p) {
                dev_queue->trans_start = 0;
                *need_watchdog_p = 1;
        }
}

void dev_activate(struct net_device *dev)
{
        int need_watchdog;

        /* No queueing discipline is attached to device;
         * create default one for devices, which need queueing
         * and noqueue_qdisc for virtual interfaces
         */

        if (dev->qdisc == &noop_qdisc)
                attach_default_qdiscs(dev);

        if (!netif_carrier_ok(dev))
                /* Delay activation until next carrier-on event */
                return;

        need_watchdog = 0;
        netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
        if (dev_ingress_queue(dev))
                transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);

        if (need_watchdog) {
                netif_trans_update(dev);
                dev_watchdog_up(dev);
        }
}
EXPORT_SYMBOL(dev_activate);

static void qdisc_deactivate(struct Qdisc *qdisc)
{
        if (qdisc->flags & TCQ_F_BUILTIN)
                return;

        set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
}

static void dev_deactivate_queue(struct net_device *dev,
                                 struct netdev_queue *dev_queue,
                                 void *_qdisc_default)
{
        struct Qdisc *qdisc_default = _qdisc_default;
        struct Qdisc *qdisc;

        qdisc = rtnl_dereference(dev_queue->qdisc);
        if (qdisc) {
                qdisc_deactivate(qdisc);
                rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
        }
}

static void dev_reset_queue(struct net_device *dev,
                            struct netdev_queue *dev_queue,
                            void *_unused)
{
        struct Qdisc *qdisc;
        bool nolock;

        qdisc = dev_queue->qdisc_sleeping;
        if (!qdisc)
                return;

        nolock = qdisc->flags & TCQ_F_NOLOCK;

        if (nolock)
                spin_lock_bh(&qdisc->seqlock);
        spin_lock_bh(qdisc_lock(qdisc));

        qdisc_reset(qdisc);

        spin_unlock_bh(qdisc_lock(qdisc));
        if (nolock)
                spin_unlock_bh(&qdisc->seqlock);
}

static bool some_qdisc_is_busy(struct net_device *dev)
{
        unsigned int i;

        for (i = 0; i < dev->num_tx_queues; i++) {
                struct netdev_queue *dev_queue;
                spinlock_t *root_lock;
                struct Qdisc *q;
                int val;

                dev_queue = netdev_get_tx_queue(dev, i);
                q = dev_queue->qdisc_sleeping;

                root_lock = qdisc_lock(q);
                spin_lock_bh(root_lock);

                val = (qdisc_is_running(q) ||
                       test_bit(__QDISC_STATE_SCHED, &q->state));

                spin_unlock_bh(root_lock);

                if (val)
                        return true;
        }
        return false;
}

/**
 *      dev_deactivate_many - deactivate transmissions on several devices
 *      @head: list of devices to deactivate
 *
 *      This function returns only when all outstanding transmissions
 *      have completed, unless all devices are in dismantle phase.
 */
void dev_deactivate_many(struct list_head *head)
{
        struct net_device *dev;

        list_for_each_entry(dev, head, close_list) {
                netdev_for_each_tx_queue(dev, dev_deactivate_queue,
                                         &noop_qdisc);
                if (dev_ingress_queue(dev))
                        dev_deactivate_queue(dev, dev_ingress_queue(dev),
                                             &noop_qdisc);

                dev_watchdog_down(dev);
        }

        /* Wait for outstanding qdisc-less dev_queue_xmit calls or
         * outstanding qdisc enqueuing calls.
         * This is avoided if all devices are in dismantle phase :
         * Caller will call synchronize_net() for us
         */
        synchronize_net();

        list_for_each_entry(dev, head, close_list) {
                netdev_for_each_tx_queue(dev, dev_reset_queue, NULL);

                if (dev_ingress_queue(dev))
                        dev_reset_queue(dev, dev_ingress_queue(dev), NULL);
        }

        /* Wait for outstanding qdisc_run calls. */
        list_for_each_entry(dev, head, close_list) {
                while (some_qdisc_is_busy(dev)) {
                        /* wait_event() would avoid this sleep-loop but would
                         * require expensive checks in the fast paths of packet
                         * processing which isn't worth it.
                         */
                        schedule_timeout_uninterruptible(1);
                }
        }
}

void dev_deactivate(struct net_device *dev)
{
        LIST_HEAD(single);

        list_add(&dev->close_list, &single);
        dev_deactivate_many(&single);
        list_del(&single);
}
EXPORT_SYMBOL(dev_deactivate);

static int qdisc_change_tx_queue_len(struct net_device *dev,
                                     struct netdev_queue *dev_queue)
{
        struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
        const struct Qdisc_ops *ops = qdisc->ops;

        if (ops->change_tx_queue_len)
                return ops->change_tx_queue_len(qdisc, dev->tx_queue_len);
        return 0;
}

int dev_qdisc_change_tx_queue_len(struct net_device *dev)
{
        bool up = dev->flags & IFF_UP;
        unsigned int i;
        int ret = 0;

        if (up)
                dev_deactivate(dev);

        for (i = 0; i < dev->num_tx_queues; i++) {
                ret = qdisc_change_tx_queue_len(dev, &dev->_tx[i]);

                /* TODO: revert changes on a partial failure */
                if (ret)
                        break;
        }

        if (up)
                dev_activate(dev);
        return ret;
}

static void dev_init_scheduler_queue(struct net_device *dev,
                                     struct netdev_queue *dev_queue,
                                     void *_qdisc)
{
        struct Qdisc *qdisc = _qdisc;

        rcu_assign_pointer(dev_queue->qdisc, qdisc);
        dev_queue->qdisc_sleeping = qdisc;
}

void dev_init_scheduler(struct net_device *dev)
{
        dev->qdisc = &noop_qdisc;
        netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
        if (dev_ingress_queue(dev))
                dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);

        timer_setup(&dev->watchdog_timer, dev_watchdog, 0);
}

static void shutdown_scheduler_queue(struct net_device *dev,
                                     struct netdev_queue *dev_queue,
                                     void *_qdisc_default)
{
        struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
        struct Qdisc *qdisc_default = _qdisc_default;

        if (qdisc) {
                rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
                dev_queue->qdisc_sleeping = qdisc_default;

                qdisc_put(qdisc);
        }
}

void dev_shutdown(struct net_device *dev)
{
        netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
        if (dev_ingress_queue(dev))
                shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
        qdisc_put(dev->qdisc);
        dev->qdisc = &noop_qdisc;

        WARN_ON(timer_pending(&dev->watchdog_timer));
}

void psched_ratecfg_precompute(struct psched_ratecfg *r,
                               const struct tc_ratespec *conf,
                               u64 rate64)
{
        memset(r, 0, sizeof(*r));
        r->overhead = conf->overhead;
        r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
        r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
        r->mult = 1;
        /*
         * The deal here is to replace a divide by a reciprocal one
         * in fast path (a reciprocal divide is a multiply and a shift)
         *
         * Normal formula would be :
         *  time_in_ns = (NSEC_PER_SEC * len) / rate_bps
         *
         * We compute mult/shift to use instead :
         *  time_in_ns = (len * mult) >> shift;
         *
         * We try to get the highest possible mult value for accuracy,
         * but have to make sure no overflows will ever happen.
         */
        if (r->rate_bytes_ps > 0) {
                u64 factor = NSEC_PER_SEC;

                for (;;) {
                        r->mult = div64_u64(factor, r->rate_bytes_ps);
                        if (r->mult & (1U << 31) || factor & (1ULL << 63))
                                break;
                        factor <<= 1;
                        r->shift++;
                }
        }
}
EXPORT_SYMBOL(psched_ratecfg_precompute);

static void mini_qdisc_rcu_func(struct rcu_head *head)
{
}

void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
                          struct tcf_proto *tp_head)
{
        /* Protected with chain0->filter_chain_lock.
         * Can't access chain directly because tp_head can be NULL.
         */
        struct mini_Qdisc *miniq_old =
                rcu_dereference_protected(*miniqp->p_miniq, 1);
        struct mini_Qdisc *miniq;

        if (!tp_head) {
                RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
                /* Wait for flying RCU callback before it is freed. */
                rcu_barrier();
                return;
        }

        miniq = !miniq_old || miniq_old == &miniqp->miniq2 ?
                &miniqp->miniq1 : &miniqp->miniq2;

        /* We need to make sure that readers won't see the miniq
         * we are about to modify. So wait until previous call_rcu callback
         * is done.
         */
        rcu_barrier();
        miniq->filter_list = tp_head;
        rcu_assign_pointer(*miniqp->p_miniq, miniq);

        if (miniq_old)
                /* This is counterpart of the rcu barriers above. We need to
                 * block potential new user of miniq_old until all readers
                 * are not seeing it.
                 */
                call_rcu(&miniq_old->rcu, mini_qdisc_rcu_func);
}
EXPORT_SYMBOL(mini_qdisc_pair_swap);

void mini_qdisc_pair_block_init(struct mini_Qdisc_pair *miniqp,
                                struct tcf_block *block)
{
        miniqp->miniq1.block = block;
        miniqp->miniq2.block = block;
}
EXPORT_SYMBOL(mini_qdisc_pair_block_init);

void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
                          struct mini_Qdisc __rcu **p_miniq)
{
        miniqp->miniq1.cpu_bstats = qdisc->cpu_bstats;
        miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats;
        miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats;
        miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats;
        miniqp->p_miniq = p_miniq;
}
EXPORT_SYMBOL(mini_qdisc_pair_init);