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

	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, classid);
	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,
					cl->classid);
		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 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);
	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,
					  sch->handle);
	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,
	.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 = {
	.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);