// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * net/sched/sch_gred.c Generic Random Early Detection queue.
 *
 * Authors:    J Hadi Salim (hadi@cyberus.ca) 1998-2002
 *
 *             991129: -  Bug fix with grio mode
 *                     - a better sing. AvgQ mode with Grio(WRED)
 *                     - A finer grained VQ dequeue based on suggestion
 *                       from Ren Liu
 *                     - More error checks
 *
 *  For all the glorious comments look at include/net/red.h
 */

#include <linux/slab.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <net/pkt_cls.h>
#include <net/pkt_sched.h>
#include <net/red.h>

#define GRED_DEF_PRIO (MAX_DPs / 2)
#define GRED_VQ_MASK (MAX_DPs - 1)

#define GRED_VQ_RED_FLAGS       (TC_RED_ECN | TC_RED_HARDDROP)

struct gred_sched_data;
struct gred_sched;

struct gred_sched_data {
        u32             limit;          /* HARD maximal queue length    */
        u32             DP;             /* the drop parameters */
        u32             red_flags;      /* virtualQ version of red_flags */
        u64             bytesin;        /* bytes seen on virtualQ so far*/
        u32             packetsin;      /* packets seen on virtualQ so far*/
        u32             backlog;        /* bytes on the virtualQ */
        u8              prio;           /* the prio of this vq */

        struct red_parms parms;
        struct red_vars  vars;
        struct red_stats stats;
};

enum {
        GRED_WRED_MODE = 1,
        GRED_RIO_MODE,
};

struct gred_sched {
        struct gred_sched_data *tab[MAX_DPs];
        unsigned long   flags;
        u32             red_flags;
        u32             DPs;
        u32             def;
        struct red_vars wred_set;
        struct tc_gred_qopt_offload *opt;
};

static inline int gred_wred_mode(struct gred_sched *table)
{
        return test_bit(GRED_WRED_MODE, &table->flags);
}

static inline void gred_enable_wred_mode(struct gred_sched *table)
{
        __set_bit(GRED_WRED_MODE, &table->flags);
}

static inline void gred_disable_wred_mode(struct gred_sched *table)
{
        __clear_bit(GRED_WRED_MODE, &table->flags);
}

static inline int gred_rio_mode(struct gred_sched *table)
{
        return test_bit(GRED_RIO_MODE, &table->flags);
}

static inline void gred_enable_rio_mode(struct gred_sched *table)
{
        __set_bit(GRED_RIO_MODE, &table->flags);
}

static inline void gred_disable_rio_mode(struct gred_sched *table)
{
        __clear_bit(GRED_RIO_MODE, &table->flags);
}

static inline int gred_wred_mode_check(struct Qdisc *sch)
{
        struct gred_sched *table = qdisc_priv(sch);
        int i;

        /* Really ugly O(n^2) but shouldn't be necessary too frequent. */
        for (i = 0; i < table->DPs; i++) {
                struct gred_sched_data *q = table->tab[i];
                int n;

                if (q == NULL)
                        continue;

                for (n = i + 1; n < table->DPs; n++)
                        if (table->tab[n] && table->tab[n]->prio == q->prio)
                                return 1;
        }

        return 0;
}

static inline unsigned int gred_backlog(struct gred_sched *table,
                                        struct gred_sched_data *q,
                                        struct Qdisc *sch)
{
        if (gred_wred_mode(table))
                return sch->qstats.backlog;
        else
                return q->backlog;
}

static inline u16 tc_index_to_dp(struct sk_buff *skb)
{
        return skb->tc_index & GRED_VQ_MASK;
}

static inline void gred_load_wred_set(const struct gred_sched *table,
                                      struct gred_sched_data *q)
{
        q->vars.qavg = table->wred_set.qavg;
        q->vars.qidlestart = table->wred_set.qidlestart;
}

static inline void gred_store_wred_set(struct gred_sched *table,
                                       struct gred_sched_data *q)
{
        table->wred_set.qavg = q->vars.qavg;
        table->wred_set.qidlestart = q->vars.qidlestart;
}

static int gred_use_ecn(struct gred_sched_data *q)
{
        return q->red_flags & TC_RED_ECN;
}

static int gred_use_harddrop(struct gred_sched_data *q)
{
        return q->red_flags & TC_RED_HARDDROP;
}

static bool gred_per_vq_red_flags_used(struct gred_sched *table)
{
        unsigned int i;

        /* Local per-vq flags couldn't have been set unless global are 0 */
        if (table->red_flags)
                return false;
        for (i = 0; i < MAX_DPs; i++)
                if (table->tab[i] && table->tab[i]->red_flags)
                        return true;
        return false;
}

static int gred_enqueue(struct sk_buff *skb, struct Qdisc *sch,
                        struct sk_buff **to_free)
{
        struct gred_sched_data *q = NULL;
        struct gred_sched *t = qdisc_priv(sch);
        unsigned long qavg = 0;
        u16 dp = tc_index_to_dp(skb);

        if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
                dp = t->def;

                q = t->tab[dp];
                if (!q) {
                        /* Pass through packets not assigned to a DP
                         * if no default DP has been configured. This
                         * allows for DP flows to be left untouched.
                         */
                        if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <=
                                        sch->limit))
                                return qdisc_enqueue_tail(skb, sch);
                        else
                                goto drop;
                }

                /* fix tc_index? --could be controversial but needed for
                   requeueing */
                skb->tc_index = (skb->tc_index & ~GRED_VQ_MASK) | dp;
        }

        /* sum up all the qaves of prios < ours to get the new qave */
        if (!gred_wred_mode(t) && gred_rio_mode(t)) {
                int i;

                for (i = 0; i < t->DPs; i++) {
                        if (t->tab[i] && t->tab[i]->prio < q->prio &&
                            !red_is_idling(&t->tab[i]->vars))
                                qavg += t->tab[i]->vars.qavg;
                }

        }

        q->packetsin++;
        q->bytesin += qdisc_pkt_len(skb);

        if (gred_wred_mode(t))
                gred_load_wred_set(t, q);

        q->vars.qavg = red_calc_qavg(&q->parms,
                                     &q->vars,
                                     gred_backlog(t, q, sch));

        if (red_is_idling(&q->vars))
                red_end_of_idle_period(&q->vars);

        if (gred_wred_mode(t))
                gred_store_wred_set(t, q);

        switch (red_action(&q->parms, &q->vars, q->vars.qavg + qavg)) {
        case RED_DONT_MARK:
                break;

        case RED_PROB_MARK:
                qdisc_qstats_overlimit(sch);
                if (!gred_use_ecn(q) || !INET_ECN_set_ce(skb)) {
                        q->stats.prob_drop++;
                        goto congestion_drop;
                }

                q->stats.prob_mark++;
                break;

        case RED_HARD_MARK:
                qdisc_qstats_overlimit(sch);
                if (gred_use_harddrop(q) || !gred_use_ecn(q) ||
                    !INET_ECN_set_ce(skb)) {
                        q->stats.forced_drop++;
                        goto congestion_drop;
                }
                q->stats.forced_mark++;
                break;
        }

        if (gred_backlog(t, q, sch) + qdisc_pkt_len(skb) <= q->limit) {
                q->backlog += qdisc_pkt_len(skb);
                return qdisc_enqueue_tail(skb, sch);
        }

        q->stats.pdrop++;
drop:
        return qdisc_drop_reason(skb, sch, to_free, SKB_DROP_REASON_QDISC_OVERLIMIT);

congestion_drop:
        qdisc_drop_reason(skb, sch, to_free, SKB_DROP_REASON_QDISC_CONGESTED);
        return NET_XMIT_CN;
}

static struct sk_buff *gred_dequeue(struct Qdisc *sch)
{
        struct sk_buff *skb;
        struct gred_sched *t = qdisc_priv(sch);

        skb = qdisc_dequeue_head(sch);

        if (skb) {
                struct gred_sched_data *q;
                u16 dp = tc_index_to_dp(skb);

                if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
                        net_warn_ratelimited("GRED: Unable to relocate VQ 0x%x after dequeue, screwing up backlog\n",
                                             tc_index_to_dp(skb));
                } else {
                        q->backlog -= qdisc_pkt_len(skb);

                        if (gred_wred_mode(t)) {
                                if (!sch->qstats.backlog)
                                        red_start_of_idle_period(&t->wred_set);
                        } else {
                                if (!q->backlog)
                                        red_start_of_idle_period(&q->vars);
                        }
                }

                return skb;
        }

        return NULL;
}

static void gred_reset(struct Qdisc *sch)
{
        int i;
        struct gred_sched *t = qdisc_priv(sch);

        qdisc_reset_queue(sch);

        for (i = 0; i < t->DPs; i++) {
                struct gred_sched_data *q = t->tab[i];

                if (!q)
                        continue;

                red_restart(&q->vars);
                q->backlog = 0;
        }
}

static void gred_offload(struct Qdisc *sch, enum tc_gred_command command)
{
        struct gred_sched *table = qdisc_priv(sch);
        struct net_device *dev = qdisc_dev(sch);
        struct tc_gred_qopt_offload *opt = table->opt;

        if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc)
                return;

        memset(opt, 0, sizeof(*opt));
        opt->command = command;
        opt->handle = sch->handle;
        opt->parent = sch->parent;

        if (command == TC_GRED_REPLACE) {
                unsigned int i;

                opt->set.grio_on = gred_rio_mode(table);
                opt->set.wred_on = gred_wred_mode(table);
                opt->set.dp_cnt = table->DPs;
                opt->set.dp_def = table->def;

                for (i = 0; i < table->DPs; i++) {
                        struct gred_sched_data *q = table->tab[i];

                        if (!q)
                                continue;
                        opt->set.tab[i].present = true;
                        opt->set.tab[i].limit = q->limit;
                        opt->set.tab[i].prio = q->prio;
                        opt->set.tab[i].min = q->parms.qth_min >> q->parms.Wlog;
                        opt->set.tab[i].max = q->parms.qth_max >> q->parms.Wlog;
                        opt->set.tab[i].is_ecn = gred_use_ecn(q);
                        opt->set.tab[i].is_harddrop = gred_use_harddrop(q);
                        opt->set.tab[i].probability = q->parms.max_P;
                        opt->set.tab[i].backlog = &q->backlog;
                }
                opt->set.qstats = &sch->qstats;
        }

        dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_GRED, opt);
}

static int gred_offload_dump_stats(struct Qdisc *sch)
{
        struct gred_sched *table = qdisc_priv(sch);
        struct tc_gred_qopt_offload *hw_stats;
        u64 bytes = 0, packets = 0;
        unsigned int i;
        int ret;

        hw_stats = kzalloc_obj(*hw_stats);
        if (!hw_stats)
                return -ENOMEM;

        hw_stats->command = TC_GRED_STATS;
        hw_stats->handle = sch->handle;
        hw_stats->parent = sch->parent;

        for (i = 0; i < MAX_DPs; i++) {
                gnet_stats_basic_sync_init(&hw_stats->stats.bstats[i]);
                if (table->tab[i])
                        hw_stats->stats.xstats[i] = &table->tab[i]->stats;
        }

        ret = qdisc_offload_dump_helper(sch, TC_SETUP_QDISC_GRED, hw_stats);
        /* Even if driver returns failure adjust the stats - in case offload
         * ended but driver still wants to adjust the values.
         */
        sch_tree_lock(sch);
        for (i = 0; i < MAX_DPs; i++) {
                if (!table->tab[i])
                        continue;
                table->tab[i]->packetsin += u64_stats_read(&hw_stats->stats.bstats[i].packets);
                table->tab[i]->bytesin += u64_stats_read(&hw_stats->stats.bstats[i].bytes);
                table->tab[i]->backlog += hw_stats->stats.qstats[i].backlog;

                bytes += u64_stats_read(&hw_stats->stats.bstats[i].bytes);
                packets += u64_stats_read(&hw_stats->stats.bstats[i].packets);
                sch->qstats.qlen += hw_stats->stats.qstats[i].qlen;
                sch->qstats.backlog += hw_stats->stats.qstats[i].backlog;
                sch->qstats.drops += hw_stats->stats.qstats[i].drops;
                sch->qstats.requeues += hw_stats->stats.qstats[i].requeues;
                sch->qstats.overlimits += hw_stats->stats.qstats[i].overlimits;
        }
        _bstats_update(&sch->bstats, bytes, packets);
        sch_tree_unlock(sch);

        kfree(hw_stats);
        return ret;
}

static inline void gred_destroy_vq(struct gred_sched_data *q)
{
        kfree(q);
}

static int gred_change_table_def(struct Qdisc *sch, struct nlattr *dps,
                                 struct netlink_ext_ack *extack)
{
        struct gred_sched *table = qdisc_priv(sch);
        struct tc_gred_sopt *sopt;
        bool red_flags_changed;
        int i;

        if (!dps)
                return -EINVAL;

        sopt = nla_data(dps);

        if (sopt->DPs > MAX_DPs) {
                NL_SET_ERR_MSG_MOD(extack, "number of virtual queues too high");
                return -EINVAL;
        }
        if (sopt->DPs == 0) {
                NL_SET_ERR_MSG_MOD(extack,
                                   "number of virtual queues can't be 0");
                return -EINVAL;
        }
        if (sopt->def_DP >= sopt->DPs) {
                NL_SET_ERR_MSG_MOD(extack, "default virtual queue above virtual queue count");
                return -EINVAL;
        }
        if (sopt->flags && gred_per_vq_red_flags_used(table)) {
                NL_SET_ERR_MSG_MOD(extack, "can't set per-Qdisc RED flags when per-virtual queue flags are used");
                return -EINVAL;
        }

        sch_tree_lock(sch);
        table->DPs = sopt->DPs;
        table->def = sopt->def_DP;
        red_flags_changed = table->red_flags != sopt->flags;
        table->red_flags = sopt->flags;

        /*
         * Every entry point to GRED is synchronized with the above code
         * and the DP is checked against DPs, i.e. shadowed VQs can no
         * longer be found so we can unlock right here.
         */
        sch_tree_unlock(sch);

        if (sopt->grio) {
                gred_enable_rio_mode(table);
                gred_disable_wred_mode(table);
                if (gred_wred_mode_check(sch))
                        gred_enable_wred_mode(table);
        } else {
                gred_disable_rio_mode(table);
                gred_disable_wred_mode(table);
        }

        if (red_flags_changed)
                for (i = 0; i < table->DPs; i++)
                        if (table->tab[i])
                                table->tab[i]->red_flags =
                                        table->red_flags & GRED_VQ_RED_FLAGS;

        for (i = table->DPs; i < MAX_DPs; i++) {
                if (table->tab[i]) {
                        pr_warn("GRED: Warning: Destroying shadowed VQ 0x%x\n",
                                i);
                        gred_destroy_vq(table->tab[i]);
                        table->tab[i] = NULL;
                }
        }

        gred_offload(sch, TC_GRED_REPLACE);
        return 0;
}

static inline int gred_change_vq(struct Qdisc *sch, int dp,
                                 struct tc_gred_qopt *ctl, int prio,
                                 u8 *stab, u32 max_P,
                                 struct gred_sched_data **prealloc,
                                 struct netlink_ext_ack *extack)
{
        struct gred_sched *table = qdisc_priv(sch);
        struct gred_sched_data *q = table->tab[dp];

        if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Scell_log, stab)) {
                NL_SET_ERR_MSG_MOD(extack, "invalid RED parameters");
                return -EINVAL;
        }

        if (!q) {
                table->tab[dp] = q = *prealloc;
                *prealloc = NULL;
                if (!q)
                        return -ENOMEM;
                q->red_flags = table->red_flags & GRED_VQ_RED_FLAGS;
        }

        q->DP = dp;
        q->prio = prio;
        if (ctl->limit > sch->limit)
                q->limit = sch->limit;
        else
                q->limit = ctl->limit;

        if (q->backlog == 0)
                red_end_of_idle_period(&q->vars);

        red_set_parms(&q->parms,
                      ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Plog,
                      ctl->Scell_log, stab, max_P);
        red_set_vars(&q->vars);
        return 0;
}

static const struct nla_policy gred_vq_policy[TCA_GRED_VQ_MAX + 1] = {
        [TCA_GRED_VQ_DP]        = { .type = NLA_U32 },
        [TCA_GRED_VQ_FLAGS]     = { .type = NLA_U32 },
};

static const struct nla_policy gred_vqe_policy[TCA_GRED_VQ_ENTRY_MAX + 1] = {
        [TCA_GRED_VQ_ENTRY]     = { .type = NLA_NESTED },
};

static const struct nla_policy gred_policy[TCA_GRED_MAX + 1] = {
        [TCA_GRED_PARMS]        = { .len = sizeof(struct tc_gred_qopt) },
        [TCA_GRED_STAB]         = { .len = 256 },
        [TCA_GRED_DPS]          = { .len = sizeof(struct tc_gred_sopt) },
        [TCA_GRED_MAX_P]        = { .type = NLA_U32 },
        [TCA_GRED_LIMIT]        = { .type = NLA_U32 },
        [TCA_GRED_VQ_LIST]      = { .type = NLA_NESTED },
};

static void gred_vq_apply(struct gred_sched *table, const struct nlattr *entry)
{
        struct nlattr *tb[TCA_GRED_VQ_MAX + 1];
        u32 dp;

        nla_parse_nested_deprecated(tb, TCA_GRED_VQ_MAX, entry,
                                    gred_vq_policy, NULL);

        dp = nla_get_u32(tb[TCA_GRED_VQ_DP]);

        if (tb[TCA_GRED_VQ_FLAGS])
                table->tab[dp]->red_flags = nla_get_u32(tb[TCA_GRED_VQ_FLAGS]);
}

static void gred_vqs_apply(struct gred_sched *table, struct nlattr *vqs)
{
        const struct nlattr *attr;
        int rem;

        nla_for_each_nested(attr, vqs, rem) {
                switch (nla_type(attr)) {
                case TCA_GRED_VQ_ENTRY:
                        gred_vq_apply(table, attr);
                        break;
                }
        }
}

static int gred_vq_validate(struct gred_sched *table, u32 cdp,
                            const struct nlattr *entry,
                            struct netlink_ext_ack *extack)
{
        struct nlattr *tb[TCA_GRED_VQ_MAX + 1];
        int err;
        u32 dp;

        err = nla_parse_nested_deprecated(tb, TCA_GRED_VQ_MAX, entry,
                                          gred_vq_policy, extack);
        if (err < 0)
                return err;

        if (!tb[TCA_GRED_VQ_DP]) {
                NL_SET_ERR_MSG_MOD(extack, "Virtual queue with no index specified");
                return -EINVAL;
        }
        dp = nla_get_u32(tb[TCA_GRED_VQ_DP]);
        if (dp >= table->DPs) {
                NL_SET_ERR_MSG_MOD(extack, "Virtual queue with index out of bounds");
                return -EINVAL;
        }
        if (dp != cdp && !table->tab[dp]) {
                NL_SET_ERR_MSG_MOD(extack, "Virtual queue not yet instantiated");
                return -EINVAL;
        }

        if (tb[TCA_GRED_VQ_FLAGS]) {
                u32 red_flags = nla_get_u32(tb[TCA_GRED_VQ_FLAGS]);

                if (table->red_flags && table->red_flags != red_flags) {
                        NL_SET_ERR_MSG_MOD(extack, "can't change per-virtual queue RED flags when per-Qdisc flags are used");
                        return -EINVAL;
                }
                if (red_flags & ~GRED_VQ_RED_FLAGS) {
                        NL_SET_ERR_MSG_MOD(extack,
                                           "invalid RED flags specified");
                        return -EINVAL;
                }
        }

        return 0;
}

static int gred_vqs_validate(struct gred_sched *table, u32 cdp,
                             struct nlattr *vqs, struct netlink_ext_ack *extack)
{
        const struct nlattr *attr;
        int rem, err;

        err = nla_validate_nested_deprecated(vqs, TCA_GRED_VQ_ENTRY_MAX,
                                             gred_vqe_policy, extack);
        if (err < 0)
                return err;

        nla_for_each_nested(attr, vqs, rem) {
                switch (nla_type(attr)) {
                case TCA_GRED_VQ_ENTRY:
                        err = gred_vq_validate(table, cdp, attr, extack);
                        if (err)
                                return err;
                        break;
                default:
                        NL_SET_ERR_MSG_MOD(extack, "GRED_VQ_LIST can contain only entry attributes");
                        return -EINVAL;
                }
        }

        if (rem > 0) {
                NL_SET_ERR_MSG_MOD(extack, "Trailing data after parsing virtual queue list");
                return -EINVAL;
        }

        return 0;
}

static int gred_change(struct Qdisc *sch, struct nlattr *opt,
                       struct netlink_ext_ack *extack)
{
        struct gred_sched *table = qdisc_priv(sch);
        struct tc_gred_qopt *ctl;
        struct nlattr *tb[TCA_GRED_MAX + 1];
        int err, prio = GRED_DEF_PRIO;
        u8 *stab;
        u32 max_P;
        struct gred_sched_data *prealloc;

        err = nla_parse_nested_deprecated(tb, TCA_GRED_MAX, opt, gred_policy,
                                          extack);
        if (err < 0)
                return err;

        if (tb[TCA_GRED_PARMS] == NULL && tb[TCA_GRED_STAB] == NULL) {
                if (tb[TCA_GRED_LIMIT] != NULL)
                        sch->limit = nla_get_u32(tb[TCA_GRED_LIMIT]);
                return gred_change_table_def(sch, tb[TCA_GRED_DPS], extack);
        }

        if (tb[TCA_GRED_PARMS] == NULL ||
            tb[TCA_GRED_STAB] == NULL ||
            tb[TCA_GRED_LIMIT] != NULL) {
                NL_SET_ERR_MSG_MOD(extack, "can't configure Qdisc and virtual queue at the same time");
                return -EINVAL;
        }

        max_P = nla_get_u32_default(tb[TCA_GRED_MAX_P], 0);

        ctl = nla_data(tb[TCA_GRED_PARMS]);
        stab = nla_data(tb[TCA_GRED_STAB]);

        if (ctl->DP >= table->DPs) {
                NL_SET_ERR_MSG_MOD(extack, "virtual queue index above virtual queue count");
                return -EINVAL;
        }

        if (tb[TCA_GRED_VQ_LIST]) {
                err = gred_vqs_validate(table, ctl->DP, tb[TCA_GRED_VQ_LIST],
                                        extack);
                if (err)
                        return err;
        }

        if (gred_rio_mode(table)) {
                if (ctl->prio == 0) {
                        int def_prio = GRED_DEF_PRIO;

                        if (table->tab[table->def])
                                def_prio = table->tab[table->def]->prio;

                        printk(KERN_DEBUG "GRED: DP %u does not have a prio "
                               "setting default to %d\n", ctl->DP, def_prio);

                        prio = def_prio;
                } else
                        prio = ctl->prio;
        }

        prealloc = kzalloc_obj(*prealloc);
        sch_tree_lock(sch);

        err = gred_change_vq(sch, ctl->DP, ctl, prio, stab, max_P, &prealloc,
                             extack);
        if (err < 0)
                goto err_unlock_free;

        if (tb[TCA_GRED_VQ_LIST])
                gred_vqs_apply(table, tb[TCA_GRED_VQ_LIST]);

        if (gred_rio_mode(table)) {
                gred_disable_wred_mode(table);
                if (gred_wred_mode_check(sch))
                        gred_enable_wred_mode(table);
        }

        sch_tree_unlock(sch);
        kfree(prealloc);

        gred_offload(sch, TC_GRED_REPLACE);
        return 0;

err_unlock_free:
        sch_tree_unlock(sch);
        kfree(prealloc);
        return err;
}

static int gred_init(struct Qdisc *sch, struct nlattr *opt,
                     struct netlink_ext_ack *extack)
{
        struct gred_sched *table = qdisc_priv(sch);
        struct nlattr *tb[TCA_GRED_MAX + 1];
        int err;

        if (!opt)
                return -EINVAL;

        err = nla_parse_nested_deprecated(tb, TCA_GRED_MAX, opt, gred_policy,
                                          extack);
        if (err < 0)
                return err;

        if (tb[TCA_GRED_PARMS] || tb[TCA_GRED_STAB]) {
                NL_SET_ERR_MSG_MOD(extack,
                                   "virtual queue configuration can't be specified at initialization time");
                return -EINVAL;
        }

        if (tb[TCA_GRED_LIMIT])
                sch->limit = nla_get_u32(tb[TCA_GRED_LIMIT]);
        else
                sch->limit = qdisc_dev(sch)->tx_queue_len
                             * psched_mtu(qdisc_dev(sch));

        if (qdisc_dev(sch)->netdev_ops->ndo_setup_tc) {
                table->opt = kzalloc_obj(*table->opt);
                if (!table->opt)
                        return -ENOMEM;
        }

        return gred_change_table_def(sch, tb[TCA_GRED_DPS], extack);
}

static int gred_dump(struct Qdisc *sch, struct sk_buff *skb)
{
        struct gred_sched *table = qdisc_priv(sch);
        struct nlattr *parms, *vqs, *opts = NULL;
        int i;
        u32 max_p[MAX_DPs];
        struct tc_gred_sopt sopt = {
                .DPs    = table->DPs,
                .def_DP = table->def,
                .grio   = gred_rio_mode(table),
                .flags  = table->red_flags,
        };

        if (gred_offload_dump_stats(sch))
                goto nla_put_failure;

        opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
        if (opts == NULL)
                goto nla_put_failure;
        if (nla_put(skb, TCA_GRED_DPS, sizeof(sopt), &sopt))
                goto nla_put_failure;

        for (i = 0; i < MAX_DPs; i++) {
                struct gred_sched_data *q = table->tab[i];

                max_p[i] = q ? q->parms.max_P : 0;
        }
        if (nla_put(skb, TCA_GRED_MAX_P, sizeof(max_p), max_p))
                goto nla_put_failure;

        if (nla_put_u32(skb, TCA_GRED_LIMIT, sch->limit))
                goto nla_put_failure;

        /* Old style all-in-one dump of VQs */
        parms = nla_nest_start_noflag(skb, TCA_GRED_PARMS);
        if (parms == NULL)
                goto nla_put_failure;

        for (i = 0; i < MAX_DPs; i++) {
                struct gred_sched_data *q = table->tab[i];
                struct tc_gred_qopt opt;
                unsigned long qavg;

                memset(&opt, 0, sizeof(opt));

                if (!q) {
                        /* hack -- fix at some point with proper message
                           This is how we indicate to tc that there is no VQ
                           at this DP */

                        opt.DP = MAX_DPs + i;
                        goto append_opt;
                }

                opt.limit       = q->limit;
                opt.DP          = q->DP;
                opt.backlog     = gred_backlog(table, q, sch);
                opt.prio        = q->prio;
                opt.qth_min     = q->parms.qth_min >> q->parms.Wlog;
                opt.qth_max     = q->parms.qth_max >> q->parms.Wlog;
                opt.Wlog        = q->parms.Wlog;
                opt.Plog        = q->parms.Plog;
                opt.Scell_log   = q->parms.Scell_log;
                opt.early       = q->stats.prob_drop;
                opt.forced      = q->stats.forced_drop;
                opt.pdrop       = q->stats.pdrop;
                opt.packets     = q->packetsin;
                opt.bytesin     = q->bytesin;

                if (gred_wred_mode(table))
                        gred_load_wred_set(table, q);

                qavg = red_calc_qavg(&q->parms, &q->vars,
                                     q->vars.qavg >> q->parms.Wlog);
                opt.qave = qavg >> q->parms.Wlog;

append_opt:
                if (nla_append(skb, sizeof(opt), &opt) < 0)
                        goto nla_put_failure;
        }

        nla_nest_end(skb, parms);

        /* Dump the VQs again, in more structured way */
        vqs = nla_nest_start_noflag(skb, TCA_GRED_VQ_LIST);
        if (!vqs)
                goto nla_put_failure;

        for (i = 0; i < MAX_DPs; i++) {
                struct gred_sched_data *q = table->tab[i];
                struct nlattr *vq;

                if (!q)
                        continue;

                vq = nla_nest_start_noflag(skb, TCA_GRED_VQ_ENTRY);
                if (!vq)
                        goto nla_put_failure;

                if (nla_put_u32(skb, TCA_GRED_VQ_DP, q->DP))
                        goto nla_put_failure;

                if (nla_put_u32(skb, TCA_GRED_VQ_FLAGS, q->red_flags))
                        goto nla_put_failure;

                /* Stats */
                if (nla_put_u64_64bit(skb, TCA_GRED_VQ_STAT_BYTES, q->bytesin,
                                      TCA_GRED_VQ_PAD))
                        goto nla_put_failure;
                if (nla_put_u32(skb, TCA_GRED_VQ_STAT_PACKETS, q->packetsin))
                        goto nla_put_failure;
                if (nla_put_u32(skb, TCA_GRED_VQ_STAT_BACKLOG,
                                gred_backlog(table, q, sch)))
                        goto nla_put_failure;
                if (nla_put_u32(skb, TCA_GRED_VQ_STAT_PROB_DROP,
                                q->stats.prob_drop))
                        goto nla_put_failure;
                if (nla_put_u32(skb, TCA_GRED_VQ_STAT_PROB_MARK,
                                q->stats.prob_mark))
                        goto nla_put_failure;
                if (nla_put_u32(skb, TCA_GRED_VQ_STAT_FORCED_DROP,
                                q->stats.forced_drop))
                        goto nla_put_failure;
                if (nla_put_u32(skb, TCA_GRED_VQ_STAT_FORCED_MARK,
                                q->stats.forced_mark))
                        goto nla_put_failure;
                if (nla_put_u32(skb, TCA_GRED_VQ_STAT_PDROP, q->stats.pdrop))
                        goto nla_put_failure;

                nla_nest_end(skb, vq);
        }
        nla_nest_end(skb, vqs);

        return nla_nest_end(skb, opts);

nla_put_failure:
        nla_nest_cancel(skb, opts);
        return -EMSGSIZE;
}

static void gred_destroy(struct Qdisc *sch)
{
        struct gred_sched *table = qdisc_priv(sch);
        int i;

        for (i = 0; i < table->DPs; i++)
                gred_destroy_vq(table->tab[i]);

        if (table->opt)
                gred_offload(sch, TC_GRED_DESTROY);
        kfree(table->opt);
}

static struct Qdisc_ops gred_qdisc_ops __read_mostly = {
        .id             =       "gred",
        .priv_size      =       sizeof(struct gred_sched),
        .enqueue        =       gred_enqueue,
        .dequeue        =       gred_dequeue,
        .peek           =       qdisc_peek_head,
        .init           =       gred_init,
        .reset          =       gred_reset,
        .destroy        =       gred_destroy,
        .change         =       gred_change,
        .dump           =       gred_dump,
        .owner          =       THIS_MODULE,
};
MODULE_ALIAS_NET_SCH("gred");

static int __init gred_module_init(void)
{
        return register_qdisc(&gred_qdisc_ops);
}

static void __exit gred_module_exit(void)
{
        unregister_qdisc(&gred_qdisc_ops);
}

module_init(gred_module_init)
module_exit(gred_module_exit)

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Generic Random Early Detection qdisc");