Linux v2.6.17-rc2

[linux-2.6/next.git] / net / sched / sch_hfsc.c

/*
 * Copyright (c) 2003 Patrick McHardy, <kaber@trash.net>
 *
 * 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 <olwi@aq.ml.com.ua> 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/config.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/jiffies.h>
#include <linux/compiler.h>
#include <linux/spinlock.h>
#include <linux/skbuff.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/timer.h>
#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/rtnetlink.h>
#include <linux/pkt_sched.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>
#include <asm/system.h>
#include <asm/div64.h>

#define HFSC_DEBUG 1

/*
 * 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 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
{
        u32             classid;        /* class id */
        unsigned int    refcnt;         /* usage count */

        struct gnet_stats_basic bstats;
        struct gnet_stats_queue qstats;
        struct gnet_stats_rate_est rate_est;
        spinlock_t      *stats_lock;
        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 hlist;         /* hash list 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 initalization
                                           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 */
};

#define HFSC_HSIZE      16

struct hfsc_sched
{
        u16     defcls;                         /* default class id */
        struct hfsc_class root;                 /* root class */
        struct list_head clhash[HFSC_HSIZE];    /* class hash */
        struct rb_root eligible;                /* eligible tree */
        struct list_head droplist;              /* active leaf class list (for
                                                   dropping) */
        struct sk_buff_head requeue;            /* requeued packet */
        struct timer_list wd_timer;             /* watchdog timer */
};

/*
 * macros
 */
#ifdef CONFIG_NET_SCH_CLK_GETTIMEOFDAY
#include <linux/time.h>
#undef PSCHED_GET_TIME
#define PSCHED_GET_TIME(stamp)                                          \
do {                                                                    \
        struct timeval tv;                                              \
        do_gettimeofday(&tv);                                           \
        (stamp) = 1ULL * USEC_PER_SEC * tv.tv_sec + tv.tv_usec;         \
} while (0)
#endif

#if HFSC_DEBUG
#define ASSERT(cond)                                                    \
do {                                                                    \
        if (unlikely(!(cond)))                                          \
                printk("assertion %s failed at %s:%i (%s)\n",           \
                       #cond, __FILE__, __LINE__, __FUNCTION__);        \
} while (0)
#else
#define ASSERT(cond)
#endif /* HFSC_DEBUG */

#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
 *
 * Clock source resolution (CONFIG_NET_SCH_CLK_*)
 *  JIFFIES: for 48<=HZ<=1534 resolution is between 0.63us and 1.27us.
 *  CPU: resolution is between 0.5us and 1us.
 *  GETTIMEOFDAY: resolution is exactly 1us.
 *
 * 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.
 *
 * Note: We can afford the additional accuracy (altq hfsc keeps at most
 * 3 effective digits) thanks to the fact that linux clock is bounded
 * much more tightly.
 *
 *  bits/sec      100Kbps     1Mbps     10Mbps     100Mbps    1Gbps
 *  ------------+-------------------------------------------------------
 *  bytes/0.5us   6.25e-3    62.5e-3    625e-3     6250e-e    62500e-3
 *  bytes/us      12.5e-3    125e-3     1250e-3    12500e-3   125000e-3
 *  bytes/1.27us  15.875e-3  158.75e-3  1587.5e-3  15875e-3   158750e-3
 *
 *  0.5us/byte    160        16         1.6        0.16       0.016
 *  us/byte       80         8          0.8        0.08       0.008
 *  1.27us/byte   63         6.3        0.63       0.063      0.0063
 */
#define SM_SHIFT        20
#define ISM_SHIFT       18

#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_JIFFIE2US(HZ) - 1;
        do_div(sm, PSCHED_JIFFIE2US(HZ));
        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_JIFFIE2US(HZ) << 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_JIFFIE2US(HZ));
        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_JIFFIE2US(HZ)) >> 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_JIFFIE2US(HZ));
        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;
        return;
}

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

        PSCHED_GET_TIME(cur_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)
                                        PSCHED_GET_TIME(cur_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.
         */
}

/*
 * hack to get length of first packet in queue.
 */
static unsigned int
qdisc_peek_len(struct Qdisc *sch)
{
        struct sk_buff *skb;
        unsigned int len;

        skb = sch->dequeue(sch);
        if (skb == NULL) {
                if (net_ratelimit())
                        printk("qdisc_peek_len: non work-conserving qdisc ?\n");
                return 0;
        }
        len = skb->len;
        if (unlikely(sch->ops->requeue(skb, sch) != NET_XMIT_SUCCESS)) {
                if (net_ratelimit())
                        printk("qdisc_peek_len: failed to requeue\n");
                return 0;
        }
        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);
        if (len > 0) {
                update_vf(cl, 0, 0);
                set_passive(cl);
                sch->q.qlen -= 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;
                }
                cl->level = level + 1;
        } while ((cl = cl->cl_parent) != NULL);
}

static inline unsigned int
hfsc_hash(u32 h)
{
        h ^= h >> 8;
        h ^= h >> 4;

        return h & (HFSC_HSIZE - 1);
}

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

        list_for_each_entry(cl, &q->clhash[hfsc_hash(classid)], hlist) {
                if (cl->classid == classid)
                        return cl;
        }
        return NULL;
}

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 int
hfsc_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
                  struct rtattr **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 rtattr *opt = tca[TCA_OPTIONS-1];
        struct rtattr *tb[TCA_HFSC_MAX];
        struct tc_service_curve *rsc = NULL, *fsc = NULL, *usc = NULL;
        u64 cur_time;

        if (opt == NULL || rtattr_parse_nested(tb, TCA_HFSC_MAX, opt))
                return -EINVAL;

        if (tb[TCA_HFSC_RSC-1]) {
                if (RTA_PAYLOAD(tb[TCA_HFSC_RSC-1]) < sizeof(*rsc))
                        return -EINVAL;
                rsc = RTA_DATA(tb[TCA_HFSC_RSC-1]);
                if (rsc->m1 == 0 && rsc->m2 == 0)
                        rsc = NULL;
        }

        if (tb[TCA_HFSC_FSC-1]) {
                if (RTA_PAYLOAD(tb[TCA_HFSC_FSC-1]) < sizeof(*fsc))
                        return -EINVAL;
                fsc = RTA_DATA(tb[TCA_HFSC_FSC-1]);
                if (fsc->m1 == 0 && fsc->m2 == 0)
                        fsc = NULL;
        }

        if (tb[TCA_HFSC_USC-1]) {
                if (RTA_PAYLOAD(tb[TCA_HFSC_USC-1]) < sizeof(*usc))
                        return -EINVAL;
                usc = RTA_DATA(tb[TCA_HFSC_USC-1]);
                if (usc->m1 == 0 && usc->m2 == 0)
                        usc = NULL;
        }

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

                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);

#ifdef CONFIG_NET_ESTIMATOR
                if (tca[TCA_RATE-1])
                        gen_replace_estimator(&cl->bstats, &cl->rate_est,
                                cl->stats_lock, tca[TCA_RATE-1]);
#endif
                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 = kmalloc(sizeof(struct hfsc_class), GFP_KERNEL);
        if (cl == NULL)
                return -ENOBUFS;
        memset(cl, 0, sizeof(struct hfsc_class));

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

        sch_tree_lock(sch);
        list_add_tail(&cl->hlist, &q->clhash[hfsc_hash(classid)]);
        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);

#ifdef CONFIG_NET_ESTIMATOR
        if (tca[TCA_RATE-1])
                gen_new_estimator(&cl->bstats, &cl->rate_est,
                        cl->stats_lock, tca[TCA_RATE-1]);
#endif
        *arg = (unsigned long)cl;
        return 0;
}

static void
hfsc_destroy_filters(struct tcf_proto **fl)
{
        struct tcf_proto *tp;

        while ((tp = *fl) != NULL) {
                *fl = tp->next;
                tcf_destroy(tp);
        }
}

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

        hfsc_destroy_filters(&cl->filter_list);
        qdisc_destroy(cl->qdisc);
#ifdef CONFIG_NET_ESTIMATOR
        gen_kill_estimator(&cl->bstats, &cl->rate_est);
#endif
        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->hlist);
        list_del(&cl->siblings);
        hfsc_adjust_levels(cl->cl_parent);
        hfsc_purge_queue(sch, cl);
        if (--cl->refcnt == 0)
                hfsc_destroy_class(sch, cl);

        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 *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_BYPASS;
        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;
                case TC_ACT_SHOT: 
                        return NULL;
                }
#elif defined(CONFIG_NET_CLS_POLICE)
                if (result == TC_POLICE_SHOT)
                        return NULL;
#endif
                if ((cl = (struct hfsc_class *)res.class) == NULL) {
                        if ((cl = hfsc_find_class(res.classid, sch)) == NULL)
                                break; /* filter selected invalid classid */
                }

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

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

        /* 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 == NULL)
                return -ENOENT;
        if (cl->level > 0)
                return -EINVAL;
        if (new == NULL) {
                new = qdisc_create_dflt(sch->dev, &pfifo_qdisc_ops);
                if (new == NULL)
                        new = &noop_qdisc;
        }

        sch_tree_lock(sch);
        hfsc_purge_queue(sch, cl);
        *old = xchg(&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 != NULL && cl->level == 0)
                return cl->qdisc;

        return NULL;
}

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);
        RTA_PUT(skb, attr, sizeof(tsc), &tsc);

        return skb->len;

 rtattr_failure:
        return -1;
}

static inline 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 rtattr_failure;

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

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

        return skb->len;

 rtattr_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;
        unsigned char *b = skb->tail;
        struct rtattr *rta = (struct rtattr *)b;

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

        RTA_PUT(skb, TCA_OPTIONS, 0, NULL);
        if (hfsc_dump_curves(skb, cl) < 0)
                goto rtattr_failure;
        rta->rta_len = skb->tail - b;
        return skb->len;

 rtattr_failure:
        skb_trim(skb, b - skb->data);
        return -1;
}

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;
        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 ||
#ifdef CONFIG_NET_ESTIMATOR
            gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
#endif
            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 hfsc_class *cl;
        unsigned int i;

        if (arg->stop)
                return;

        for (i = 0; i < HFSC_HSIZE; i++) {
                list_for_each_entry(cl, &q->clhash[i], hlist) {
                        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_watchdog(unsigned long arg)
{
        struct Qdisc *sch = (struct Qdisc *)arg;

        sch->flags &= ~TCQ_F_THROTTLED;
        netif_schedule(sch->dev);
}

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

        if ((cl = eltree_get_minel(q)) != NULL)
                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;
        }
        ASSERT(next_time != 0);
        delay = next_time - cur_time;
        delay = PSCHED_US2JIFFIE(delay);

        sch->flags |= TCQ_F_THROTTLED;
        mod_timer(&q->wd_timer, jiffies + delay);
}

static int
hfsc_init_qdisc(struct Qdisc *sch, struct rtattr *opt)
{
        struct hfsc_sched *q = qdisc_priv(sch);
        struct tc_hfsc_qopt *qopt;
        unsigned int i;

        if (opt == NULL || RTA_PAYLOAD(opt) < sizeof(*qopt))
                return -EINVAL;
        qopt = RTA_DATA(opt);

        sch->stats_lock = &sch->dev->queue_lock;

        q->defcls = qopt->defcls;
        for (i = 0; i < HFSC_HSIZE; i++)
                INIT_LIST_HEAD(&q->clhash[i]);
        q->eligible = RB_ROOT;
        INIT_LIST_HEAD(&q->droplist);
        skb_queue_head_init(&q->requeue);

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

        list_add(&q->root.hlist, &q->clhash[hfsc_hash(q->root.classid)]);

        init_timer(&q->wd_timer);
        q->wd_timer.function = hfsc_watchdog;
        q->wd_timer.data = (unsigned long)sch;

        return 0;
}

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

        if (opt == NULL || RTA_PAYLOAD(opt) < sizeof(*qopt))
                return -EINVAL;
        qopt = RTA_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;
        unsigned int i;

        for (i = 0; i < HFSC_HSIZE; i++) {
                list_for_each_entry(cl, &q->clhash[i], hlist)
                        hfsc_reset_class(cl);
        }
        __skb_queue_purge(&q->requeue);
        q->eligible = RB_ROOT;
        INIT_LIST_HEAD(&q->droplist);
        del_timer(&q->wd_timer);
        sch->flags &= ~TCQ_F_THROTTLED;
        sch->q.qlen = 0;
}

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

        for (i = 0; i < HFSC_HSIZE; i++) {
                list_for_each_entry_safe(cl, next, &q->clhash[i], hlist)
                        hfsc_destroy_class(sch, cl);
        }
        __skb_queue_purge(&q->requeue);
        del_timer(&q->wd_timer);
}

static int
hfsc_dump_qdisc(struct Qdisc *sch, struct sk_buff *skb)
{
        struct hfsc_sched *q = qdisc_priv(sch);
        unsigned char *b = skb->tail;
        struct tc_hfsc_qopt qopt;

        qopt.defcls = q->defcls;
        RTA_PUT(skb, TCA_OPTIONS, sizeof(qopt), &qopt);
        return skb->len;

 rtattr_failure:
        skb_trim(skb, b - skb->data);
        return -1;
}

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

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

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

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

        cl->bstats.packets++;
        cl->bstats.bytes += len;
        sch->bstats.packets++;
        sch->bstats.bytes += len;
        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;
        if ((skb = __skb_dequeue(&q->requeue)))
                goto out;

        PSCHED_GET_TIME(cur_time);

        /*
         * if there are eligible classes, use real-time criteria.
         * find the class with the minimum deadline among
         * the eligible classes.
         */
        if ((cl = eltree_get_mindl(q, cur_time)) != NULL) {
                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, cur_time);
                        return NULL;
                }
        }

        skb = cl->qdisc->dequeue(cl->qdisc);
        if (skb == NULL) {
                if (net_ratelimit())
                        printk("HFSC: Non-work-conserving qdisc ?\n");
                return NULL;
        }

        update_vf(cl, skb->len, cur_time);
        if (realtime)
                cl->cl_cumul += skb->len;

        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);
        }

 out:
        sch->flags &= ~TCQ_F_THROTTLED;
        sch->q.qlen--;

        return skb;
}

static int
hfsc_requeue(struct sk_buff *skb, struct Qdisc *sch)
{
        struct hfsc_sched *q = qdisc_priv(sch);

        __skb_queue_head(&q->requeue, skb);
        sch->q.qlen++;
        sch->qstats.requeues++;
        return NET_XMIT_SUCCESS;
}

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 struct Qdisc_class_ops hfsc_class_ops = {
        .change         = hfsc_change_class,
        .delete         = hfsc_delete_class,
        .graft          = hfsc_graft_class,
        .leaf           = hfsc_class_leaf,
        .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 = {
        .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,
        .requeue        = hfsc_requeue,
        .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);