Merge branch 'omap-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind...

[mirror_ubuntu-bionic-kernel.git] / net / sched / sch_gred.c

/*
 * net/sched/sch_gred.c Generic Random Early Detection queue.
 *
 *
 *              This program is free software; you can redistribute it and/or
 *              modify it under the terms of the GNU General Public License
 *              as published by the Free Software Foundation; either version
 *              2 of the License, or (at your option) any later version.
 *
 * Authors:    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 sugestion
 *                       from Ren Liu
 *                     - More error checks
 *
 *  For all the glorious comments look at include/net/red.h
 */

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

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

struct gred_sched_data;
struct gred_sched;

struct gred_sched_data
{
        u32             limit;          /* HARD maximal queue length    */
        u32             DP;             /* the drop pramaters */
        u32             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_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_parms wred_set;
};

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 = 0; n < table->DPs; n++)
                        if (table->tab[n] && table->tab[n] != q &&
                            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(struct gred_sched *table,
                                      struct gred_sched_data *q)
{
        q->parms.qavg = table->wred_set.qavg;
        q->parms.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->parms.qavg;
}

static inline int gred_use_ecn(struct gred_sched *t)
{
        return t->red_flags & TC_RED_ECN;
}

static inline int gred_use_harddrop(struct gred_sched *t)
{
        return t->red_flags & TC_RED_HARDDROP;
}

static int gred_enqueue(struct sk_buff *skb, struct Qdisc* sch)
{
        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;

                if ((q = t->tab[dp]) == NULL) {
                        /* 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 (skb_queue_len(&sch->q) < qdisc_dev(sch)->tx_queue_len)
                                return qdisc_enqueue_tail(skb, sch);
                        else
                                goto drop;
                }

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

        /* sum up all the qaves of prios <= to 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]->parms))
                                qavg +=t->tab[i]->parms.qavg;
                }

        }

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

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

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

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

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

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

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

                        q->stats.prob_mark++;
                        break;

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

        if (q->backlog + 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(skb, sch);

congestion_drop:
        qdisc_drop(skb, sch);
        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) {
                        if (net_ratelimit())
                                printk(KERN_WARNING "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 (!q->backlog && !gred_wred_mode(t))
                                red_start_of_idle_period(&q->parms);
                }

                return skb;
        }

        if (gred_wred_mode(t) && !red_is_idling(&t->wred_set))
                red_start_of_idle_period(&t->wred_set);

        return NULL;
}

static unsigned int gred_drop(struct Qdisc* sch)
{
        struct sk_buff *skb;
        struct gred_sched *t = qdisc_priv(sch);

        skb = qdisc_dequeue_tail(sch);
        if (skb) {
                unsigned int len = qdisc_pkt_len(skb);
                struct gred_sched_data *q;
                u16 dp = tc_index_to_dp(skb);

                if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
                        if (net_ratelimit())
                                printk(KERN_WARNING "GRED: Unable to relocate "
                                       "VQ 0x%x while dropping, screwing up "
                                       "backlog.\n", tc_index_to_dp(skb));
                } else {
                        q->backlog -= len;
                        q->stats.other++;

                        if (!q->backlog && !gred_wred_mode(t))
                                red_start_of_idle_period(&q->parms);
                }

                qdisc_drop(skb, sch);
                return len;
        }

        if (gred_wred_mode(t) && !red_is_idling(&t->wred_set))
                red_start_of_idle_period(&t->wred_set);

        return 0;

}

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->parms);
                q->backlog = 0;
        }
}

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

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

        if (dps == NULL)
                return -EINVAL;

        sopt = nla_data(dps);

        if (sopt->DPs > MAX_DPs || sopt->DPs == 0 || sopt->def_DP >= sopt->DPs)
                return -EINVAL;

        sch_tree_lock(sch);
        table->DPs = sopt->DPs;
        table->def = sopt->def_DP;
        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);
        }

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

        return 0;
}

static inline int gred_change_vq(struct Qdisc *sch, int dp,
                                 struct tc_gred_qopt *ctl, int prio, u8 *stab)
{
        struct gred_sched *table = qdisc_priv(sch);
        struct gred_sched_data *q;

        if (table->tab[dp] == NULL) {
                table->tab[dp] = kzalloc(sizeof(*q), GFP_KERNEL);
                if (table->tab[dp] == NULL)
                        return -ENOMEM;
        }

        q = table->tab[dp];
        q->DP = dp;
        q->prio = prio;
        q->limit = ctl->limit;

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

        red_set_parms(&q->parms,
                      ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Plog,
                      ctl->Scell_log, stab);

        return 0;
}

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) },
};

static int gred_change(struct Qdisc *sch, struct nlattr *opt)
{
        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;

        if (opt == NULL)
                return -EINVAL;

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

        if (tb[TCA_GRED_PARMS] == NULL && tb[TCA_GRED_STAB] == NULL)
                return gred_change_table_def(sch, opt);

        if (tb[TCA_GRED_PARMS] == NULL ||
            tb[TCA_GRED_STAB] == NULL)
                return -EINVAL;

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

        if (ctl->DP >= table->DPs)
                goto errout;

        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;
        }

        sch_tree_lock(sch);

        err = gred_change_vq(sch, ctl->DP, ctl, prio, stab);
        if (err < 0)
                goto errout_locked;

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

        err = 0;

errout_locked:
        sch_tree_unlock(sch);
errout:
        return err;
}

static int gred_init(struct Qdisc *sch, struct nlattr *opt)
{
        struct nlattr *tb[TCA_GRED_MAX + 1];
        int err;

        if (opt == NULL)
                return -EINVAL;

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

        if (tb[TCA_GRED_PARMS] || tb[TCA_GRED_STAB])
                return -EINVAL;

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

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

        opts = nla_nest_start(skb, TCA_OPTIONS);
        if (opts == NULL)
                goto nla_put_failure;
        NLA_PUT(skb, TCA_GRED_DPS, sizeof(sopt), &sopt);
        parms = nla_nest_start(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;

                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     = q->backlog;
                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.other       = q->stats.other;
                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)) {
                        q->parms.qidlestart =
                                table->tab[table->def]->parms.qidlestart;
                        q->parms.qavg = table->tab[table->def]->parms.qavg;
                }

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

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

        nla_nest_end(skb, parms);

        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++) {
                if (table->tab[i])
                        gred_destroy_vq(table->tab[i]);
        }
}

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,
        .drop           =       gred_drop,
        .init           =       gred_init,
        .reset          =       gred_reset,
        .destroy        =       gred_destroy,
        .change         =       gred_change,
        .dump           =       gred_dump,
        .owner          =       THIS_MODULE,
};

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");