sch_hfsc.c

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/*
 * Copyright (c) 2003 Patrick McHardy, <[email protected]>
 *
 * 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.
 *
 * 2003-10-17 - Ported from altq
 */
/*
 * Copyright (c) 1997-1999 Carnegie Mellon University. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation is hereby granted (including for commercial or
 * for-profit use), provided that both the copyright notice and this
 * permission notice appear in all copies of the software, derivative
 * works, or modified versions, and any portions thereof.
 *
 * THIS SOFTWARE IS EXPERIMENTAL AND IS KNOWN TO HAVE BUGS, SOME OF
 * WHICH MAY HAVE SERIOUS CONSEQUENCES.  CARNEGIE MELLON PROVIDES THIS
 * SOFTWARE IN ITS ``AS IS'' CONDITION, AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 * Carnegie Mellon encourages (but does not require) users of this
 * software to return any improvements or extensions that they make,
 * and to grant Carnegie Mellon the rights to redistribute these
 * changes without encumbrance.
 */
/*
 * H-FSC is described in Proceedings of SIGCOMM'97,
 * "A Hierarchical Fair Service Curve Algorithm for Link-Sharing,
 * Real-Time and Priority Service"
 * by Ion Stoica, Hui Zhang, and T. S. Eugene Ng.
 *
 * Oleg Cherevko <[email protected]> added the upperlimit for link-sharing.
 * when a class has an upperlimit, the fit-time is computed from the
 * upperlimit service curve.  the link-sharing scheduler does not schedule
 * a class whose fit-time exceeds the current time.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/compiler.h>
#include <linux/spinlock.h>
#include <linux/skbuff.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/init.h>
#include <linux/rtnetlink.h>
#include <linux/pkt_sched.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>
#include <asm/div64.h>

/*
 * kernel internal service curve representation:
 *   coordinates are given by 64 bit unsigned integers.
 *   x-axis: unit is clock count.
 *   y-axis: unit is byte.
 *
 *   The service curve parameters are converted to the internal
 *   representation. The slope values are scaled to avoid overflow.
 *   the inverse slope values as well as the y-projection of the 1st
 *   segment are kept in order to avoid 64-bit divide operations
 *   that are expensive on 32-bit architectures.
 */

struct internal_sc {
    u64 sm1;    /* scaled slope of the 1st segment */
    u64 ism1;   /* scaled inverse-slope of the 1st segment */
    u64 dx; /* the x-projection of the 1st segment */
    u64 dy; /* the y-projection of the 1st segment */
    u64 sm2;    /* scaled slope of the 2nd segment */
    u64 ism2;   /* scaled inverse-slope of the 2nd segment */
};

/* runtime service curve */
struct runtime_sc {
    u64 x;  /* current starting position on x-axis */
    u64 y;  /* current starting position on y-axis */
    u64 sm1;    /* scaled slope of the 1st segment */
    u64 ism1;   /* scaled inverse-slope of the 1st segment */
    u64 dx; /* the x-projection of the 1st segment */
    u64 dy; /* the y-projection of the 1st segment */
    u64 sm2;    /* scaled slope of the 2nd segment */
    u64 ism2;   /* scaled inverse-slope of the 2nd segment */
};

enum hfsc_class_flags {
    HFSC_RSC = 0x1,
    HFSC_FSC = 0x2,
    HFSC_USC = 0x4
};

struct hfsc_class {
    struct Qdisc_class_common cl_common;
    unsigned int    refcnt;     /* usage count */

    struct gnet_stats_basic_packed bstats;
    struct gnet_stats_queue qstats;
    struct gnet_stats_rate_est rate_est;
    unsigned int    level;      /* class level in hierarchy */
    struct tcf_proto *filter_list;  /* filter list */
    unsigned int    filter_cnt; /* filter count */

    struct hfsc_sched *sched;   /* scheduler data */
    struct hfsc_class *cl_parent;   /* parent class */
    struct list_head siblings;  /* sibling classes */
    struct list_head children;  /* child classes */
    struct Qdisc    *qdisc;     /* leaf qdisc */

    struct rb_node el_node;     /* qdisc's eligible tree member */
    struct rb_root vt_tree;     /* active children sorted by cl_vt */
    struct rb_node vt_node;     /* parent's vt_tree member */
    struct rb_root cf_tree;     /* active children sorted by cl_f */
    struct rb_node cf_node;     /* parent's cf_heap member */
    struct list_head dlist;     /* drop list member */

    u64 cl_total;       /* total work in bytes */
    u64 cl_cumul;       /* cumulative work in bytes done by
                       real-time criteria */

    u64 cl_d;           /* deadline*/
    u64 cl_e;           /* eligible time */
    u64 cl_vt;          /* virtual time */
    u64 cl_f;           /* time when this class will fit for
                       link-sharing, max(myf, cfmin) */
    u64 cl_myf;         /* my fit-time (calculated from this
                       class's own upperlimit curve) */
    u64 cl_myfadj;      /* my fit-time adjustment (to cancel
                       history dependence) */
    u64 cl_cfmin;       /* earliest children's fit-time (used
                       with cl_myf to obtain cl_f) */
    u64 cl_cvtmin;      /* minimal virtual time among the
                       children fit for link-sharing
                       (monotonic within a period) */
    u64 cl_vtadj;       /* intra-period cumulative vt
                       adjustment */
    u64 cl_vtoff;       /* inter-period cumulative vt offset */
    u64 cl_cvtmax;      /* max child's vt in the last period */
    u64 cl_cvtoff;      /* cumulative cvtmax of all periods */
    u64 cl_pcvtoff;     /* parent's cvtoff at initialization
                       time */

    struct internal_sc cl_rsc;  /* internal real-time service curve */
    struct internal_sc cl_fsc;  /* internal fair service curve */
    struct internal_sc cl_usc;  /* internal upperlimit service curve */
    struct runtime_sc cl_deadline;  /* deadline curve */
    struct runtime_sc cl_eligible;  /* eligible curve */
    struct runtime_sc cl_virtual;   /* virtual curve */
    struct runtime_sc cl_ulimit;    /* upperlimit curve */

    unsigned long   cl_flags;   /* which curves are valid */
    unsigned long   cl_vtperiod;    /* vt period sequence number */
    unsigned long   cl_parentperiod;/* parent's vt period sequence number*/
    unsigned long   cl_nactive; /* number of active children */
};

struct hfsc_sched {
    u16 defcls;             /* default class id */
    struct hfsc_class root;         /* root class */
    struct Qdisc_class_hash clhash;     /* class hash */
    struct rb_root eligible;        /* eligible tree */
    struct list_head droplist;      /* active leaf class list (for
                           dropping) */
    struct qdisc_watchdog watchdog;     /* watchdog timer */
};

#define HT_INFINITY 0xffffffffffffffffULL   /* infinite time value */


/*
 * eligible tree holds backlogged classes being sorted by their eligible times.
 * there is one eligible tree per hfsc instance.
 */

static void
eltree_insert(struct hfsc_class *cl)
{
    struct rb_node **p = &cl->sched->eligible.rb_node;
    struct rb_node *parent = NULL;
    struct hfsc_class *cl1;

    while (*p != NULL) {
        parent = *p;
        cl1 = rb_entry(parent, struct hfsc_class, el_node);
        if (cl->cl_e >= cl1->cl_e)
            p = &parent->rb_right;
        else
            p = &parent->rb_left;
    }
    rb_link_node(&cl->el_node, parent, p);
    rb_insert_color(&cl->el_node, &cl->sched->eligible);
}

static inline void
eltree_remove(struct hfsc_class *cl)
{
    rb_erase(&cl->el_node, &cl->sched->eligible);
}

static inline void
eltree_update(struct hfsc_class *cl)
{
    eltree_remove(cl);
    eltree_insert(cl);
}

/* find the class with the minimum deadline among the eligible classes */
static inline struct hfsc_class *
eltree_get_mindl(struct hfsc_sched *q, u64 cur_time)
{
    struct hfsc_class *p, *cl = NULL;
    struct rb_node *n;

    for (n = rb_first(&q->eligible); n != NULL; n = rb_next(n)) {
        p = rb_entry(n, struct hfsc_class, el_node);
        if (p->cl_e > cur_time)
            break;
        if (cl == NULL || p->cl_d < cl->cl_d)
            cl = p;
    }
    return cl;
}

/* find the class with minimum eligible time among the eligible classes */
static inline struct hfsc_class *
eltree_get_minel(struct hfsc_sched *q)
{
    struct rb_node *n;

    n = rb_first(&q->eligible);
    if (n == NULL)
        return NULL;
    return rb_entry(n, struct hfsc_class, el_node);
}

/*
 * vttree holds holds backlogged child classes being sorted by their virtual
 * time. each intermediate class has one vttree.
 */
static void
vttree_insert(struct hfsc_class *cl)
{
    struct rb_node **p = &cl->cl_parent->vt_tree.rb_node;
    struct rb_node *parent = NULL;
    struct hfsc_class *cl1;

    while (*p != NULL) {
        parent = *p;
        cl1 = rb_entry(parent, struct hfsc_class, vt_node);
        if (cl->cl_vt >= cl1->cl_vt)
            p = &parent->rb_right;
        else
            p = &parent->rb_left;
    }
    rb_link_node(&cl->vt_node, parent, p);
    rb_insert_color(&cl->vt_node, &cl->cl_parent->vt_tree);
}

static inline void
vttree_remove(struct hfsc_class *cl)
{
    rb_erase(&cl->vt_node, &cl->cl_parent->vt_tree);
}

static inline void
vttree_update(struct hfsc_class *cl)
{
    vttree_remove(cl);
    vttree_insert(cl);
}

static inline struct hfsc_class *
vttree_firstfit(struct hfsc_class *cl, u64 cur_time)
{
    struct hfsc_class *p;
    struct rb_node *n;

    for (n = rb_first(&cl->vt_tree); n != NULL; n = rb_next(n)) {
        p = rb_entry(n, struct hfsc_class, vt_node);
        if (p->cl_f <= cur_time)
            return p;
    }
    return NULL;
}

/*
 * get the leaf class with the minimum vt in the hierarchy
 */
static struct hfsc_class *
vttree_get_minvt(struct hfsc_class *cl, u64 cur_time)
{
    /* if root-class's cfmin is bigger than cur_time nothing to do */
    if (cl->cl_cfmin > cur_time)
        return NULL;

    while (cl->level > 0) {
        cl = vttree_firstfit(cl, cur_time);
        if (cl == NULL)
            return NULL;
        /*
         * update parent's cl_cvtmin.
         */
        if (cl->cl_parent->cl_cvtmin < cl->cl_vt)
            cl->cl_parent->cl_cvtmin = cl->cl_vt;
    }
    return cl;
}

static void
cftree_insert(struct hfsc_class *cl)
{
    struct rb_node **p = &cl->cl_parent->cf_tree.rb_node;
    struct rb_node *parent = NULL;
    struct hfsc_class *cl1;

    while (*p != NULL) {
        parent = *p;
        cl1 = rb_entry(parent, struct hfsc_class, cf_node);
        if (cl->cl_f >= cl1->cl_f)
            p = &parent->rb_right;
        else
            p = &parent->rb_left;
    }
    rb_link_node(&cl->cf_node, parent, p);
    rb_insert_color(&cl->cf_node, &cl->cl_parent->cf_tree);
}

static inline void
cftree_remove(struct hfsc_class *cl)
{
    rb_erase(&cl->cf_node, &cl->cl_parent->cf_tree);
}

static inline void
cftree_update(struct hfsc_class *cl)
{
    cftree_remove(cl);
    cftree_insert(cl);
}

/*
 * service curve support functions
 *
 *  external service curve parameters
 *  m: bps
 *  d: us
 *  internal service curve parameters
 *  sm: (bytes/psched_us) << SM_SHIFT
 *  ism: (psched_us/byte) << ISM_SHIFT
 *  dx: psched_us
 *
 * The clock source resolution with ktime and PSCHED_SHIFT 10 is 1.024us.
 *
 * sm and ism are scaled in order to keep effective digits.
 * SM_SHIFT and ISM_SHIFT are selected to keep at least 4 effective
 * digits in decimal using the following table.
 *
 *  bits/sec      100Kbps     1Mbps     10Mbps     100Mbps    1Gbps
 *  ------------+-------------------------------------------------------
 *  bytes/1.024us 12.8e-3    128e-3     1280e-3    12800e-3   128000e-3
 *
 *  1.024us/byte  78.125     7.8125     0.78125    0.078125   0.0078125
 *
 * So, for PSCHED_SHIFT 10 we need: SM_SHIFT 20, ISM_SHIFT 18.
 */
#define SM_SHIFT    (30 - PSCHED_SHIFT)
#define ISM_SHIFT   (8 + PSCHED_SHIFT)

#define SM_MASK     ((1ULL << SM_SHIFT) - 1)
#define ISM_MASK    ((1ULL << ISM_SHIFT) - 1)

static inline u64
seg_x2y(u64 x, u64 sm)
{
    u64 y;

    /*
     * compute
     *  y = x * sm >> SM_SHIFT
     * but divide it for the upper and lower bits to avoid overflow
     */
    y = (x >> SM_SHIFT) * sm + (((x & SM_MASK) * sm) >> SM_SHIFT);
    return y;
}

static inline u64
seg_y2x(u64 y, u64 ism)
{
    u64 x;

    if (y == 0)
        x = 0;
    else if (ism == HT_INFINITY)
        x = HT_INFINITY;
    else {
        x = (y >> ISM_SHIFT) * ism
            + (((y & ISM_MASK) * ism) >> ISM_SHIFT);
    }
    return x;
}

/* Convert m (bps) into sm (bytes/psched us) */
static u64
m2sm(u32 m)
{
    u64 sm;

    sm = ((u64)m << SM_SHIFT);
    sm += PSCHED_TICKS_PER_SEC - 1;
    do_div(sm, PSCHED_TICKS_PER_SEC);
    return sm;
}

/* convert m (bps) into ism (psched us/byte) */
static u64
m2ism(u32 m)
{
    u64 ism;

    if (m == 0)
        ism = HT_INFINITY;
    else {
        ism = ((u64)PSCHED_TICKS_PER_SEC << ISM_SHIFT);
        ism += m - 1;
        do_div(ism, m);
    }
    return ism;
}

/* convert d (us) into dx (psched us) */
static u64
d2dx(u32 d)
{
    u64 dx;

    dx = ((u64)d * PSCHED_TICKS_PER_SEC);
    dx += USEC_PER_SEC - 1;
    do_div(dx, USEC_PER_SEC);
    return dx;
}

/* convert sm (bytes/psched us) into m (bps) */
static u32
sm2m(u64 sm)
{
    u64 m;

    m = (sm * PSCHED_TICKS_PER_SEC) >> SM_SHIFT;
    return (u32)m;
}

/* convert dx (psched us) into d (us) */
static u32
dx2d(u64 dx)
{
    u64 d;

    d = dx * USEC_PER_SEC;
    do_div(d, PSCHED_TICKS_PER_SEC);
    return (u32)d;
}

static void
sc2isc(struct tc_service_curve *sc, struct internal_sc *isc)
{
    isc->sm1  = m2sm(sc->m1);
    isc->ism1 = m2ism(sc->m1);
    isc->dx   = d2dx(sc->d);
    isc->dy   = seg_x2y(isc->dx, isc->sm1);
    isc->sm2  = m2sm(sc->m2);
    isc->ism2 = m2ism(sc->m2);
}

/*
 * initialize the runtime service curve with the given internal
 * service curve starting at (x, y).
 */
static void
rtsc_init(struct runtime_sc *rtsc, struct internal_sc *isc, u64 x, u64 y)
{
    rtsc->x    = x;
    rtsc->y    = y;
    rtsc->sm1  = isc->sm1;
    rtsc->ism1 = isc->ism1;
    rtsc->dx   = isc->dx;
    rtsc->dy   = isc->dy;
    rtsc->sm2  = isc->sm2;
    rtsc->ism2 = isc->ism2;
}

/*
 * calculate the y-projection of the runtime service curve by the
 * given x-projection value
 */
static u64
rtsc_y2x(struct runtime_sc *rtsc, u64 y)
{
    u64 x;

    if (y < rtsc->y)
        x = rtsc->x;
    else if (y <= rtsc->y + rtsc->dy) {
        /* x belongs to the 1st segment */
        if (rtsc->dy == 0)
            x = rtsc->x + rtsc->dx;
        else
            x = rtsc->x + seg_y2x(y - rtsc->y, rtsc->ism1);
    } else {
        /* x belongs to the 2nd segment */
        x = rtsc->x + rtsc->dx
            + seg_y2x(y - rtsc->y - rtsc->dy, rtsc->ism2);
    }
    return x;
}

static u64
rtsc_x2y(struct runtime_sc *rtsc, u64 x)
{
    u64 y;

    if (x <= rtsc->x)
        y = rtsc->y;
    else if (x <= rtsc->x + rtsc->dx)
        /* y belongs to the 1st segment */
        y = rtsc->y + seg_x2y(x - rtsc->x, rtsc->sm1);
    else
        /* y belongs to the 2nd segment */
        y = rtsc->y + rtsc->dy
            + seg_x2y(x - rtsc->x - rtsc->dx, rtsc->sm2);
    return y;
}

/*
 * update the runtime service curve by taking the minimum of the current
 * runtime service curve and the service curve starting at (x, y).
 */
static void
rtsc_min(struct runtime_sc *rtsc, struct internal_sc *isc, u64 x, u64 y)
{
    u64 y1, y2, dx, dy;
    u32 dsm;

    if (isc->sm1 <= isc->sm2) {
        /* service curve is convex */
        y1 = rtsc_x2y(rtsc, x);
        if (y1 < y)
            /* the current rtsc is smaller */
            return;
        rtsc->x = x;
        rtsc->y = y;
        return;
    }

    /*
     * service curve is concave
     * compute the two y values of the current rtsc
     *  y1: at x
     *  y2: at (x + dx)
     */
    y1 = rtsc_x2y(rtsc, x);
    if (y1 <= y) {
        /* rtsc is below isc, no change to rtsc */
        return;
    }

    y2 = rtsc_x2y(rtsc, x + isc->dx);
    if (y2 >= y + isc->dy) {
        /* rtsc is above isc, replace rtsc by isc */
        rtsc->x = x;
        rtsc->y = y;
        rtsc->dx = isc->dx;
        rtsc->dy = isc->dy;
        return;
    }

    /*
     * the two curves intersect
     * compute the offsets (dx, dy) using the reverse
     * function of seg_x2y()
     *  seg_x2y(dx, sm1) == seg_x2y(dx, sm2) + (y1 - y)
     */
    dx = (y1 - y) << SM_SHIFT;
    dsm = isc->sm1 - isc->sm2;
    do_div(dx, dsm);
    /*
     * check if (x, y1) belongs to the 1st segment of rtsc.
     * if so, add the offset.
     */
    if (rtsc->x + rtsc->dx > x)
        dx += rtsc->x + rtsc->dx - x;
    dy = seg_x2y(dx, isc->sm1);

    rtsc->x = x;
    rtsc->y = y;
    rtsc->dx = dx;
    rtsc->dy = dy;
}

static void
init_ed(struct hfsc_class *cl, unsigned int next_len)
{
    u64 cur_time = psched_get_time();

    /* update the deadline curve */
    rtsc_min(&cl->cl_deadline, &cl->cl_rsc, cur_time, cl->cl_cumul);

    /*
     * update the eligible curve.
     * for concave, it is equal to the deadline curve.
     * for convex, it is a linear curve with slope m2.
     */
    cl->cl_eligible = cl->cl_deadline;
    if (cl->cl_rsc.sm1 <= cl->cl_rsc.sm2) {
        cl->cl_eligible.dx = 0;
        cl->cl_eligible.dy = 0;
    }

    /* compute e and d */
    cl->cl_e = rtsc_y2x(&cl->cl_eligible, cl->cl_cumul);
    cl->cl_d = rtsc_y2x(&cl->cl_deadline, cl->cl_cumul + next_len);

    eltree_insert(cl);
}

static void
update_ed(struct hfsc_class *cl, unsigned int next_len)
{
    cl->cl_e = rtsc_y2x(&cl->cl_eligible, cl->cl_cumul);
    cl->cl_d = rtsc_y2x(&cl->cl_deadline, cl->cl_cumul + next_len);

    eltree_update(cl);
}

static inline void
update_d(struct hfsc_class *cl, unsigned int next_len)
{
    cl->cl_d = rtsc_y2x(&cl->cl_deadline, cl->cl_cumul + next_len);
}

static inline void
update_cfmin(struct hfsc_class *cl)
{
    struct rb_node *n = rb_first(&cl->cf_tree);
    struct hfsc_class *p;

    if (n == NULL) {
        cl->cl_cfmin = 0;
        return;
    }
    p = rb_entry(n, struct hfsc_class, cf_node);
    cl->cl_cfmin = p->cl_f;
}

static void
init_vf(struct hfsc_class *cl, unsigned int len)
{
    struct hfsc_class *max_cl;
    struct rb_node *n;
    u64 vt, f, cur_time;
    int go_active;

    cur_time = 0;
    go_active = 1;
    for (; cl->cl_parent != NULL; cl = cl->cl_parent) {
        if (go_active && cl->cl_nactive++ == 0)
            go_active = 1;
        else
            go_active = 0;

        if (go_active) {
            n = rb_last(&cl->cl_parent->vt_tree);
            if (n != NULL) {
                max_cl = rb_entry(n, struct hfsc_class, vt_node);
                /*
                 * set vt to the average of the min and max
                 * classes.  if the parent's period didn't
                 * change, don't decrease vt of the class.
                 */
                vt = max_cl->cl_vt;
                if (cl->cl_parent->cl_cvtmin != 0)
                    vt = (cl->cl_parent->cl_cvtmin + vt)/2;

                if (cl->cl_parent->cl_vtperiod !=
                    cl->cl_parentperiod || vt > cl->cl_vt)
                    cl->cl_vt = vt;
            } else {
                /*
                 * first child for a new parent backlog period.
                 * add parent's cvtmax to cvtoff to make a new
                 * vt (vtoff + vt) larger than the vt in the
                 * last period for all children.
                 */
                vt = cl->cl_parent->cl_cvtmax;
                cl->cl_parent->cl_cvtoff += vt;
                cl->cl_parent->cl_cvtmax = 0;
                cl->cl_parent->cl_cvtmin = 0;
                cl->cl_vt = 0;
            }

            cl->cl_vtoff = cl->cl_parent->cl_cvtoff -
                            cl->cl_pcvtoff;

            /* update the virtual curve */
            vt = cl->cl_vt + cl->cl_vtoff;
            rtsc_min(&cl->cl_virtual, &cl->cl_fsc, vt,
                              cl->cl_total);
            if (cl->cl_virtual.x == vt) {
                cl->cl_virtual.x -= cl->cl_vtoff;
                cl->cl_vtoff = 0;
            }
            cl->cl_vtadj = 0;

            cl->cl_vtperiod++;  /* increment vt period */
            cl->cl_parentperiod = cl->cl_parent->cl_vtperiod;
            if (cl->cl_parent->cl_nactive == 0)
                cl->cl_parentperiod++;
            cl->cl_f = 0;

            vttree_insert(cl);
            cftree_insert(cl);

            if (cl->cl_flags & HFSC_USC) {
                /* class has upper limit curve */
                if (cur_time == 0)
                    cur_time = psched_get_time();

                /* update the ulimit curve */
                rtsc_min(&cl->cl_ulimit, &cl->cl_usc, cur_time,
                     cl->cl_total);
                /* compute myf */
                cl->cl_myf = rtsc_y2x(&cl->cl_ulimit,
                              cl->cl_total);
                cl->cl_myfadj = 0;
            }
        }

        f = max(cl->cl_myf, cl->cl_cfmin);
        if (f != cl->cl_f) {
            cl->cl_f = f;
            cftree_update(cl);
        }
        update_cfmin(cl->cl_parent);
    }
}

static void
update_vf(struct hfsc_class *cl, unsigned int len, u64 cur_time)
{
    u64 f; /* , myf_bound, delta; */
    int go_passive = 0;

    if (cl->qdisc->q.qlen == 0 && cl->cl_flags & HFSC_FSC)
        go_passive = 1;

    for (; cl->cl_parent != NULL; cl = cl->cl_parent) {
        cl->cl_total += len;

        if (!(cl->cl_flags & HFSC_FSC) || cl->cl_nactive == 0)
            continue;

        if (go_passive && --cl->cl_nactive == 0)
            go_passive = 1;
        else
            go_passive = 0;

        if (go_passive) {
            /* no more active child, going passive */

            /* update cvtmax of the parent class */
            if (cl->cl_vt > cl->cl_parent->cl_cvtmax)
                cl->cl_parent->cl_cvtmax = cl->cl_vt;

            /* remove this class from the vt tree */
            vttree_remove(cl);

            cftree_remove(cl);
            update_cfmin(cl->cl_parent);

            continue;
        }

        /*
         * update vt and f
         */
        cl->cl_vt = rtsc_y2x(&cl->cl_virtual, cl->cl_total)
                - cl->cl_vtoff + cl->cl_vtadj;

        /*
         * if vt of the class is smaller than cvtmin,
         * the class was skipped in the past due to non-fit.
         * if so, we need to adjust vtadj.
         */
        if (cl->cl_vt < cl->cl_parent->cl_cvtmin) {
            cl->cl_vtadj += cl->cl_parent->cl_cvtmin - cl->cl_vt;
            cl->cl_vt = cl->cl_parent->cl_cvtmin;
        }

        /* update the vt tree */
        vttree_update(cl);

        if (cl->cl_flags & HFSC_USC) {
            cl->cl_myf = cl->cl_myfadj + rtsc_y2x(&cl->cl_ulimit,
                                  cl->cl_total);
#if 0
            /*
             * This code causes classes to stay way under their
             * limit when multiple classes are used at gigabit
             * speed. needs investigation. -kaber
             */
            /*
             * if myf lags behind by more than one clock tick
             * from the current time, adjust myfadj to prevent
             * a rate-limited class from going greedy.
             * in a steady state under rate-limiting, myf
             * fluctuates within one clock tick.
             */
            myf_bound = cur_time - PSCHED_JIFFIE2US(1);
            if (cl->cl_myf < myf_bound) {
                delta = cur_time - cl->cl_myf;
                cl->cl_myfadj += delta;
                cl->cl_myf += delta;
            }
#endif
        }

        f = max(cl->cl_myf, cl->cl_cfmin);
        if (f != cl->cl_f) {
            cl->cl_f = f;
            cftree_update(cl);
            update_cfmin(cl->cl_parent);
        }
    }
}

static void
set_active(struct hfsc_class *cl, unsigned int len)
{
    if (cl->cl_flags & HFSC_RSC)
        init_ed(cl, len);
    if (cl->cl_flags & HFSC_FSC)
        init_vf(cl, len);

    list_add_tail(&cl->dlist, &cl->sched->droplist);
}

static void
set_passive(struct hfsc_class *cl)
{
    if (cl->cl_flags & HFSC_RSC)
        eltree_remove(cl);

    list_del(&cl->dlist);

    /*
     * vttree is now handled in update_vf() so that update_vf(cl, 0, 0)
     * needs to be called explicitly to remove a class from vttree.
     */
}

static unsigned int
qdisc_peek_len(struct Qdisc *sch)
{
    struct sk_buff *skb;
    unsigned int len;

    skb = sch->ops->peek(sch);
    if (skb == NULL) {
        qdisc_warn_nonwc("qdisc_peek_len", sch);
        return 0;
    }
    len = qdisc_pkt_len(skb);

    return len;
}

static void
hfsc_purge_queue(struct Qdisc *sch, struct hfsc_class *cl)
{
    unsigned int len = cl->qdisc->q.qlen;

    qdisc_reset(cl->qdisc);
    qdisc_tree_decrease_qlen(cl->qdisc, len);
}

static void
hfsc_adjust_levels(struct hfsc_class *cl)
{
    struct hfsc_class *p;
    unsigned int level;

    do {
        level = 0;
        list_for_each_entry(p, &cl->children, siblings) {
            if (p->level >= level)
                level = p->level + 1;
        }
        cl->level = level;
    } while ((cl = cl->cl_parent) != NULL);
}

static inline struct hfsc_class *
hfsc_find_class(u32 classid, struct Qdisc *sch)
{
    struct hfsc_sched *q = qdisc_priv(sch);
    struct Qdisc_class_common *clc;

    clc = qdisc_class_find(&q->clhash, classid);
    if (clc == NULL)
        return NULL;
    return container_of(clc, struct hfsc_class, cl_common);
}

static void
hfsc_change_rsc(struct hfsc_class *cl, struct tc_service_curve *rsc,
        u64 cur_time)
{
    sc2isc(rsc, &cl->cl_rsc);
    rtsc_init(&cl->cl_deadline, &cl->cl_rsc, cur_time, cl->cl_cumul);
    cl->cl_eligible = cl->cl_deadline;
    if (cl->cl_rsc.sm1 <= cl->cl_rsc.sm2) {
        cl->cl_eligible.dx = 0;
        cl->cl_eligible.dy = 0;
    }
    cl->cl_flags |= HFSC_RSC;
}

static void
hfsc_change_fsc(struct hfsc_class *cl, struct tc_service_curve *fsc)
{
    sc2isc(fsc, &cl->cl_fsc);
    rtsc_init(&cl->cl_virtual, &cl->cl_fsc, cl->cl_vt, cl->cl_total);
    cl->cl_flags |= HFSC_FSC;
}

static void
hfsc_change_usc(struct hfsc_class *cl, struct tc_service_curve *usc,
        u64 cur_time)
{
    sc2isc(usc, &cl->cl_usc);
    rtsc_init(&cl->cl_ulimit, &cl->cl_usc, cur_time, cl->cl_total);
    cl->cl_flags |= HFSC_USC;
}

static const struct nla_policy hfsc_policy[TCA_HFSC_MAX + 1] = {
    [TCA_HFSC_RSC]  = { .len = sizeof(struct tc_service_curve) },
    [TCA_HFSC_FSC]  = { .len = sizeof(struct tc_service_curve) },
    [TCA_HFSC_USC]  = { .len = sizeof(struct tc_service_curve) },
};

static int
hfsc_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
          struct nlattr **tca, unsigned long *arg)
{
    struct hfsc_sched *q = qdisc_priv(sch);
    struct hfsc_class *cl = (struct hfsc_class *)*arg;
    struct hfsc_class *parent = NULL;
    struct nlattr *opt = tca[TCA_OPTIONS];
    struct nlattr *tb[TCA_HFSC_MAX + 1];
    struct tc_service_curve *rsc = NULL, *fsc = NULL, *usc = NULL;
    u64 cur_time;
    int err;

    if (opt == NULL)
        return -EINVAL;

    err = nla_parse_nested(tb, TCA_HFSC_MAX, opt, hfsc_policy);
    if (err < 0)
        return err;

    if (tb[TCA_HFSC_RSC]) {
        rsc = nla_data(tb[TCA_HFSC_RSC]);
        if (rsc->m1 == 0 && rsc->m2 == 0)
            rsc = NULL;
    }

    if (tb[TCA_HFSC_FSC]) {
        fsc = nla_data(tb[TCA_HFSC_FSC]);
        if (fsc->m1 == 0 && fsc->m2 == 0)
            fsc = NULL;
    }

    if (tb[TCA_HFSC_USC]) {
        usc = nla_data(tb[TCA_HFSC_USC]);
        if (usc->m1 == 0 && usc->m2 == 0)
            usc = NULL;
    }

    if (cl != NULL) {
        if (parentid) {
            if (cl->cl_parent &&
                cl->cl_parent->cl_common.classid != parentid)
                return -EINVAL;
            if (cl->cl_parent == NULL && parentid != TC_H_ROOT)
                return -EINVAL;
        }
        cur_time = psched_get_time();

        if (tca[TCA_RATE]) {
            err = gen_replace_estimator(&cl->bstats, &cl->rate_est,
                          qdisc_root_sleeping_lock(sch),
                          tca[TCA_RATE]);
            if (err)
                return err;
        }

        sch_tree_lock(sch);
        if (rsc != NULL)
            hfsc_change_rsc(cl, rsc, cur_time);
        if (fsc != NULL)
            hfsc_change_fsc(cl, fsc);
        if (usc != NULL)
            hfsc_change_usc(cl, usc, cur_time);

        if (cl->qdisc->q.qlen != 0) {
            if (cl->cl_flags & HFSC_RSC)
                update_ed(cl, qdisc_peek_len(cl->qdisc));
            if (cl->cl_flags & HFSC_FSC)
                update_vf(cl, 0, cur_time);
        }
        sch_tree_unlock(sch);

        return 0;
    }

    if (parentid == TC_H_ROOT)
        return -EEXIST;

    parent = &q->root;
    if (parentid) {
        parent = hfsc_find_class(parentid, sch);
        if (parent == NULL)
            return -ENOENT;
    }

    if (classid == 0 || TC_H_MAJ(classid ^ sch->handle) != 0)
        return -EINVAL;
    if (hfsc_find_class(classid, sch))
        return -EEXIST;

    if (rsc == NULL && fsc == NULL)
        return -EINVAL;

    cl = kzalloc(sizeof(struct hfsc_class), GFP_KERNEL);
    if (cl == NULL)
        return -ENOBUFS;

    if (tca[TCA_RATE]) {
        err = gen_new_estimator(&cl->bstats, &cl->rate_est,
                    qdisc_root_sleeping_lock(sch),
                    tca[TCA_RATE]);
        if (err) {
            kfree(cl);
            return err;
        }
    }

    if (rsc != NULL)
        hfsc_change_rsc(cl, rsc, 0);
    if (fsc != NULL)
        hfsc_change_fsc(cl, fsc);
    if (usc != NULL)
        hfsc_change_usc(cl, usc, 0);

    cl->cl_common.classid = classid;
    cl->refcnt    = 1;
    cl->sched     = q;
    cl->cl_parent = parent;
    cl->qdisc = qdisc_create_dflt(sch->dev_queue,
                      &pfifo_qdisc_ops, classid);
    if (cl->qdisc == NULL)
        cl->qdisc = &noop_qdisc;
    INIT_LIST_HEAD(&cl->children);
    cl->vt_tree = RB_ROOT;
    cl->cf_tree = RB_ROOT;

    sch_tree_lock(sch);
    qdisc_class_hash_insert(&q->clhash, &cl->cl_common);
    list_add_tail(&cl->siblings, &parent->children);
    if (parent->level == 0)
        hfsc_purge_queue(sch, parent);
    hfsc_adjust_levels(parent);
    cl->cl_pcvtoff = parent->cl_cvtoff;
    sch_tree_unlock(sch);

    qdisc_class_hash_grow(sch, &q->clhash);

    *arg = (unsigned long)cl;
    return 0;
}

static void
hfsc_destroy_class(struct Qdisc *sch, struct hfsc_class *cl)
{
    struct hfsc_sched *q = qdisc_priv(sch);

    tcf_destroy_chain(&cl->filter_list);
    qdisc_destroy(cl->qdisc);
    gen_kill_estimator(&cl->bstats, &cl->rate_est);
    if (cl != &q->root)
        kfree(cl);
}

static int
hfsc_delete_class(struct Qdisc *sch, unsigned long arg)
{
    struct hfsc_sched *q = qdisc_priv(sch);
    struct hfsc_class *cl = (struct hfsc_class *)arg;

    if (cl->level > 0 || cl->filter_cnt > 0 || cl == &q->root)
        return -EBUSY;

    sch_tree_lock(sch);

    list_del(&cl->siblings);
    hfsc_adjust_levels(cl->cl_parent);

    hfsc_purge_queue(sch, cl);
    qdisc_class_hash_remove(&q->clhash, &cl->cl_common);

    BUG_ON(--cl->refcnt == 0);
    /*
     * This shouldn't happen: we "hold" one cops->get() when called
     * from tc_ctl_tclass; the destroy method is done from cops->put().
     */

    sch_tree_unlock(sch);
    return 0;
}

static struct hfsc_class *
hfsc_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
{
    struct hfsc_sched *q = qdisc_priv(sch);
    struct hfsc_class *head, *cl;
    struct tcf_result res;
    struct tcf_proto *tcf;
    int result;

    if (TC_H_MAJ(skb->priority ^ sch->handle) == 0 &&
        (cl = hfsc_find_class(skb->priority, sch)) != NULL)
        if (cl->level == 0)
            return cl;

    *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
    head = &q->root;
    tcf = q->root.filter_list;
    while (tcf && (result = tc_classify(skb, tcf, &res)) >= 0) {
#ifdef CONFIG_NET_CLS_ACT
        switch (result) {
        case TC_ACT_QUEUED:
        case TC_ACT_STOLEN:
            *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
        case TC_ACT_SHOT:
            return NULL;
        }
#endif
        cl = (struct hfsc_class *)res.class;
        if (!cl) {
            cl = hfsc_find_class(res.classid, sch);
            if (!cl)
                break; /* filter selected invalid classid */
            if (cl->level >= head->level)
                break; /* filter may only point downwards */
        }

        if (cl->level == 0)
            return cl; /* hit leaf class */

        /* apply inner filter chain */
        tcf = cl->filter_list;
        head = cl;
    }

    /* classification failed, try default class */
    cl = hfsc_find_class(TC_H_MAKE(TC_H_MAJ(sch->handle), q->defcls), sch);
    if (cl == NULL || cl->level > 0)
        return NULL;

    return cl;
}

static int
hfsc_graft_class(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
         struct Qdisc **old)
{
    struct hfsc_class *cl = (struct hfsc_class *)arg;

    if (cl->level > 0)
        return -EINVAL;
    if (new == NULL) {
        new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
                    cl->cl_common.classid);
        if (new == NULL)
            new = &noop_qdisc;
    }

    sch_tree_lock(sch);
    hfsc_purge_queue(sch, cl);
    *old = cl->qdisc;
    cl->qdisc = new;
    sch_tree_unlock(sch);
    return 0;
}

static struct Qdisc *
hfsc_class_leaf(struct Qdisc *sch, unsigned long arg)
{
    struct hfsc_class *cl = (struct hfsc_class *)arg;

    if (cl->level == 0)
        return cl->qdisc;

    return NULL;
}

static void
hfsc_qlen_notify(struct Qdisc *sch, unsigned long arg)
{
    struct hfsc_class *cl = (struct hfsc_class *)arg;

    if (cl->qdisc->q.qlen == 0) {
        update_vf(cl, 0, 0);
        set_passive(cl);
    }
}

static unsigned long
hfsc_get_class(struct Qdisc *sch, u32 classid)
{
    struct hfsc_class *cl = hfsc_find_class(classid, sch);

    if (cl != NULL)
        cl->refcnt++;

    return (unsigned long)cl;
}

static void
hfsc_put_class(struct Qdisc *sch, unsigned long arg)
{
    struct hfsc_class *cl = (struct hfsc_class *)arg;

    if (--cl->refcnt == 0)
        hfsc_destroy_class(sch, cl);
}

static unsigned long
hfsc_bind_tcf(struct Qdisc *sch, unsigned long parent, u32 classid)
{
    struct hfsc_class *p = (struct hfsc_class *)parent;
    struct hfsc_class *cl = hfsc_find_class(classid, sch);

    if (cl != NULL) {
        if (p != NULL && p->level <= cl->level)
            return 0;
        cl->filter_cnt++;
    }

    return (unsigned long)cl;
}

static void
hfsc_unbind_tcf(struct Qdisc *sch, unsigned long arg)
{
    struct hfsc_class *cl = (struct hfsc_class *)arg;

    cl->filter_cnt--;
}

static struct tcf_proto **
hfsc_tcf_chain(struct Qdisc *sch, unsigned long arg)
{
    struct hfsc_sched *q = qdisc_priv(sch);
    struct hfsc_class *cl = (struct hfsc_class *)arg;

    if (cl == NULL)
        cl = &q->root;

    return &cl->filter_list;
}

static int
hfsc_dump_sc(struct sk_buff *skb, int attr, struct internal_sc *sc)
{
    struct tc_service_curve tsc;

    tsc.m1 = sm2m(sc->sm1);
    tsc.d  = dx2d(sc->dx);
    tsc.m2 = sm2m(sc->sm2);
    if (nla_put(skb, attr, sizeof(tsc), &tsc))
        goto nla_put_failure;

    return skb->len;

 nla_put_failure:
    return -1;
}

static int
hfsc_dump_curves(struct sk_buff *skb, struct hfsc_class *cl)
{
    if ((cl->cl_flags & HFSC_RSC) &&
        (hfsc_dump_sc(skb, TCA_HFSC_RSC, &cl->cl_rsc) < 0))
        goto nla_put_failure;

    if ((cl->cl_flags & HFSC_FSC) &&
        (hfsc_dump_sc(skb, TCA_HFSC_FSC, &cl->cl_fsc) < 0))
        goto nla_put_failure;

    if ((cl->cl_flags & HFSC_USC) &&
        (hfsc_dump_sc(skb, TCA_HFSC_USC, &cl->cl_usc) < 0))
        goto nla_put_failure;

    return skb->len;

 nla_put_failure:
    return -1;
}

static int
hfsc_dump_class(struct Qdisc *sch, unsigned long arg, struct sk_buff *skb,
        struct tcmsg *tcm)
{
    struct hfsc_class *cl = (struct hfsc_class *)arg;
    struct nlattr *nest;

    tcm->tcm_parent = cl->cl_parent ? cl->cl_parent->cl_common.classid :
                      TC_H_ROOT;
    tcm->tcm_handle = cl->cl_common.classid;
    if (cl->level == 0)
        tcm->tcm_info = cl->qdisc->handle;

    nest = nla_nest_start(skb, TCA_OPTIONS);
    if (nest == NULL)
        goto nla_put_failure;
    if (hfsc_dump_curves(skb, cl) < 0)
        goto nla_put_failure;
    nla_nest_end(skb, nest);
    return skb->len;

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

static int
hfsc_dump_class_stats(struct Qdisc *sch, unsigned long arg,
    struct gnet_dump *d)
{
    struct hfsc_class *cl = (struct hfsc_class *)arg;
    struct tc_hfsc_stats xstats;

    cl->qstats.qlen = cl->qdisc->q.qlen;
    cl->qstats.backlog = cl->qdisc->qstats.backlog;
    xstats.level   = cl->level;
    xstats.period  = cl->cl_vtperiod;
    xstats.work    = cl->cl_total;
    xstats.rtwork  = cl->cl_cumul;

    if (gnet_stats_copy_basic(d, &cl->bstats) < 0 ||
        gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 ||
        gnet_stats_copy_queue(d, &cl->qstats) < 0)
        return -1;

    return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
}



static void
hfsc_walk(struct Qdisc *sch, struct qdisc_walker *arg)
{
    struct hfsc_sched *q = qdisc_priv(sch);
    struct hlist_node *n;
    struct hfsc_class *cl;
    unsigned int i;

    if (arg->stop)
        return;

    for (i = 0; i < q->clhash.hashsize; i++) {
        hlist_for_each_entry(cl, n, &q->clhash.hash[i],
                     cl_common.hnode) {
            if (arg->count < arg->skip) {
                arg->count++;
                continue;
            }
            if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
                arg->stop = 1;
                return;
            }
            arg->count++;
        }
    }
}

static void
hfsc_schedule_watchdog(struct Qdisc *sch)
{
    struct hfsc_sched *q = qdisc_priv(sch);
    struct hfsc_class *cl;
    u64 next_time = 0;

    cl = eltree_get_minel(q);
    if (cl)
        next_time = cl->cl_e;
    if (q->root.cl_cfmin != 0) {
        if (next_time == 0 || next_time > q->root.cl_cfmin)
            next_time = q->root.cl_cfmin;
    }
    WARN_ON(next_time == 0);
    qdisc_watchdog_schedule(&q->watchdog, next_time);
}

static int
hfsc_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
{
    struct hfsc_sched *q = qdisc_priv(sch);
    struct tc_hfsc_qopt *qopt;
    int err;

    if (opt == NULL || nla_len(opt) < sizeof(*qopt))
        return -EINVAL;
    qopt = nla_data(opt);

    q->defcls = qopt->defcls;
    err = qdisc_class_hash_init(&q->clhash);
    if (err < 0)
        return err;
    q->eligible = RB_ROOT;
    INIT_LIST_HEAD(&q->droplist);

    q->root.cl_common.classid = sch->handle;
    q->root.refcnt  = 1;
    q->root.sched   = q;
    q->root.qdisc = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
                      sch->handle);
    if (q->root.qdisc == NULL)
        q->root.qdisc = &noop_qdisc;
    INIT_LIST_HEAD(&q->root.children);
    q->root.vt_tree = RB_ROOT;
    q->root.cf_tree = RB_ROOT;

    qdisc_class_hash_insert(&q->clhash, &q->root.cl_common);
    qdisc_class_hash_grow(sch, &q->clhash);

    qdisc_watchdog_init(&q->watchdog, sch);

    return 0;
}

static int
hfsc_change_qdisc(struct Qdisc *sch, struct nlattr *opt)
{
    struct hfsc_sched *q = qdisc_priv(sch);
    struct tc_hfsc_qopt *qopt;

    if (opt == NULL || nla_len(opt) < sizeof(*qopt))
        return -EINVAL;
    qopt = nla_data(opt);

    sch_tree_lock(sch);
    q->defcls = qopt->defcls;
    sch_tree_unlock(sch);

    return 0;
}

static void
hfsc_reset_class(struct hfsc_class *cl)
{
    cl->cl_total        = 0;
    cl->cl_cumul        = 0;
    cl->cl_d            = 0;
    cl->cl_e            = 0;
    cl->cl_vt           = 0;
    cl->cl_vtadj        = 0;
    cl->cl_vtoff        = 0;
    cl->cl_cvtmin       = 0;
    cl->cl_cvtmax       = 0;
    cl->cl_cvtoff       = 0;
    cl->cl_pcvtoff      = 0;
    cl->cl_vtperiod     = 0;
    cl->cl_parentperiod = 0;
    cl->cl_f            = 0;
    cl->cl_myf          = 0;
    cl->cl_myfadj       = 0;
    cl->cl_cfmin        = 0;
    cl->cl_nactive      = 0;

    cl->vt_tree = RB_ROOT;
    cl->cf_tree = RB_ROOT;
    qdisc_reset(cl->qdisc);

    if (cl->cl_flags & HFSC_RSC)
        rtsc_init(&cl->cl_deadline, &cl->cl_rsc, 0, 0);
    if (cl->cl_flags & HFSC_FSC)
        rtsc_init(&cl->cl_virtual, &cl->cl_fsc, 0, 0);
    if (cl->cl_flags & HFSC_USC)
        rtsc_init(&cl->cl_ulimit, &cl->cl_usc, 0, 0);
}

static void
hfsc_reset_qdisc(struct Qdisc *sch)
{
    struct hfsc_sched *q = qdisc_priv(sch);
    struct hfsc_class *cl;
    struct hlist_node *n;
    unsigned int i;

    for (i = 0; i < q->clhash.hashsize; i++) {
        hlist_for_each_entry(cl, n, &q->clhash.hash[i], cl_common.hnode)
            hfsc_reset_class(cl);
    }
    q->eligible = RB_ROOT;
    INIT_LIST_HEAD(&q->droplist);
    qdisc_watchdog_cancel(&q->watchdog);
    sch->q.qlen = 0;
}

static void
hfsc_destroy_qdisc(struct Qdisc *sch)
{
    struct hfsc_sched *q = qdisc_priv(sch);
    struct hlist_node *n, *next;
    struct hfsc_class *cl;
    unsigned int i;

    for (i = 0; i < q->clhash.hashsize; i++) {
        hlist_for_each_entry(cl, n, &q->clhash.hash[i], cl_common.hnode)
            tcf_destroy_chain(&cl->filter_list);
    }
    for (i = 0; i < q->clhash.hashsize; i++) {
        hlist_for_each_entry_safe(cl, n, next, &q->clhash.hash[i],
                      cl_common.hnode)
            hfsc_destroy_class(sch, cl);
    }
    qdisc_class_hash_destroy(&q->clhash);
    qdisc_watchdog_cancel(&q->watchdog);
}

static int
hfsc_dump_qdisc(struct Qdisc *sch, struct sk_buff *skb)
{
    struct hfsc_sched *q = qdisc_priv(sch);
    unsigned char *b = skb_tail_pointer(skb);
    struct tc_hfsc_qopt qopt;
    struct hfsc_class *cl;
    struct hlist_node *n;
    unsigned int i;

    sch->qstats.backlog = 0;
    for (i = 0; i < q->clhash.hashsize; i++) {
        hlist_for_each_entry(cl, n, &q->clhash.hash[i], cl_common.hnode)
            sch->qstats.backlog += cl->qdisc->qstats.backlog;
    }

    qopt.defcls = q->defcls;
    if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt))
        goto nla_put_failure;
    return skb->len;

 nla_put_failure:
    nlmsg_trim(skb, b);
    return -1;
}

static int
hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch)
{
    struct hfsc_class *cl;
    int uninitialized_var(err);

    cl = hfsc_classify(skb, sch, &err);
    if (cl == NULL) {
        if (err & __NET_XMIT_BYPASS)
            sch->qstats.drops++;
        kfree_skb(skb);
        return err;
    }

    err = qdisc_enqueue(skb, cl->qdisc);
    if (unlikely(err != NET_XMIT_SUCCESS)) {
        if (net_xmit_drop_count(err)) {
            cl->qstats.drops++;
            sch->qstats.drops++;
        }
        return err;
    }

    if (cl->qdisc->q.qlen == 1)
        set_active(cl, qdisc_pkt_len(skb));

    sch->q.qlen++;

    return NET_XMIT_SUCCESS;
}

static struct sk_buff *
hfsc_dequeue(struct Qdisc *sch)
{
    struct hfsc_sched *q = qdisc_priv(sch);
    struct hfsc_class *cl;
    struct sk_buff *skb;
    u64 cur_time;
    unsigned int next_len;
    int realtime = 0;

    if (sch->q.qlen == 0)
        return NULL;

    cur_time = psched_get_time();

    /*
     * if there are eligible classes, use real-time criteria.
     * find the class with the minimum deadline among
     * the eligible classes.
     */
    cl = eltree_get_mindl(q, cur_time);
    if (cl) {
        realtime = 1;
    } else {
        /*
         * use link-sharing criteria
         * get the class with the minimum vt in the hierarchy
         */
        cl = vttree_get_minvt(&q->root, cur_time);
        if (cl == NULL) {
            sch->qstats.overlimits++;
            hfsc_schedule_watchdog(sch);
            return NULL;
        }
    }

    skb = qdisc_dequeue_peeked(cl->qdisc);
    if (skb == NULL) {
        qdisc_warn_nonwc("HFSC", cl->qdisc);
        return NULL;
    }

    bstats_update(&cl->bstats, skb);
    update_vf(cl, qdisc_pkt_len(skb), cur_time);
    if (realtime)
        cl->cl_cumul += qdisc_pkt_len(skb);

    if (cl->qdisc->q.qlen != 0) {
        if (cl->cl_flags & HFSC_RSC) {
            /* update ed */
            next_len = qdisc_peek_len(cl->qdisc);
            if (realtime)
                update_ed(cl, next_len);
            else
                update_d(cl, next_len);
        }
    } else {
        /* the class becomes passive */
        set_passive(cl);
    }

    qdisc_unthrottled(sch);
    qdisc_bstats_update(sch, skb);
    sch->q.qlen--;

    return skb;
}

static unsigned int
hfsc_drop(struct Qdisc *sch)
{
    struct hfsc_sched *q = qdisc_priv(sch);
    struct hfsc_class *cl;
    unsigned int len;

    list_for_each_entry(cl, &q->droplist, dlist) {
        if (cl->qdisc->ops->drop != NULL &&
            (len = cl->qdisc->ops->drop(cl->qdisc)) > 0) {
            if (cl->qdisc->q.qlen == 0) {
                update_vf(cl, 0, 0);
                set_passive(cl);
            } else {
                list_move_tail(&cl->dlist, &q->droplist);
            }
            cl->qstats.drops++;
            sch->qstats.drops++;
            sch->q.qlen--;
            return len;
        }
    }
    return 0;
}

static const struct Qdisc_class_ops hfsc_class_ops = {
    .change     = hfsc_change_class,
    .delete     = hfsc_delete_class,
    .graft      = hfsc_graft_class,
    .leaf       = hfsc_class_leaf,
    .qlen_notify    = hfsc_qlen_notify,
    .get        = hfsc_get_class,
    .put        = hfsc_put_class,
    .bind_tcf   = hfsc_bind_tcf,
    .unbind_tcf = hfsc_unbind_tcf,
    .tcf_chain  = hfsc_tcf_chain,
    .dump       = hfsc_dump_class,
    .dump_stats = hfsc_dump_class_stats,
    .walk       = hfsc_walk
};

static struct Qdisc_ops hfsc_qdisc_ops __read_mostly = {
    .id     = "hfsc",
    .init       = hfsc_init_qdisc,
    .change     = hfsc_change_qdisc,
    .reset      = hfsc_reset_qdisc,
    .destroy    = hfsc_destroy_qdisc,
    .dump       = hfsc_dump_qdisc,
    .enqueue    = hfsc_enqueue,
    .dequeue    = hfsc_dequeue,
    .peek       = qdisc_peek_dequeued,
    .drop       = hfsc_drop,
    .cl_ops     = &hfsc_class_ops,
    .priv_size  = sizeof(struct hfsc_sched),
    .owner      = THIS_MODULE
};

static int __init
hfsc_init(void)
{
    return register_qdisc(&hfsc_qdisc_ops);
}

static void __exit
hfsc_cleanup(void)
{
    unregister_qdisc(&hfsc_qdisc_ops);
}

MODULE_LICENSE("GPL");
module_init(hfsc_init);
module_exit(hfsc_cleanup);