Subject: [PATCH 2.6]: HFSC packet scheduler

From: Patrick McHardy <[email-masked]>
Date: Thu, 29 Jan 2004 16:16:08 +0100

This is the 2.6 version of HFSC. Changes to last patch:

- don't crash on user error (non-work-conserving inner qdisc)
- trailing whitespace cleanup

Best regards,
Patrick
diff -urN linux-2.5/include/linux/pkt_sched.h linux-2.5-hfsc/include/linux/pkt_sched.h
--- linux-2.5/include/linux/pkt_sched.h	2004-01-29 15:13:26.000000000 +0100
+++ linux-2.5-hfsc/include/linux/pkt_sched.h	2004-01-29 15:18:47.000000000 +0100
@@ -290,6 +290,37 @@
 	__u32 ctokens;
 };
 
+/* HFSC section */
+
+struct tc_hfsc_qopt
+{
+	__u16	defcls;		/* default class */
+};
+
+struct tc_service_curve
+{
+	__u32	m1;		/* slope of the first segment in bps */
+	__u32	d;		/* x-projection of the first segment in us */
+	__u32	m2;		/* slope of the second segment in bps */
+};
+
+struct tc_hfsc_stats
+{
+	__u64	work;		/* total work done */
+	__u64	rtwork;		/* work done by real-time criteria */
+	__u32	period;		/* current period */
+	__u32	level;		/* class level in hierarchy */
+};
+
+enum
+{
+	TCA_HFSC_UNSPEC,
+	TCA_HFSC_RSC,
+	TCA_HFSC_FSC,
+	TCA_HFSC_USC,
+	TCA_HFSC_MAX = TCA_HFSC_USC
+};
+
 /* CBQ section */
 
 #define TC_CBQ_MAXPRIO		8
diff -urN linux-2.5/include/net/pkt_sched.h linux-2.5-hfsc/include/net/pkt_sched.h
--- linux-2.5/include/net/pkt_sched.h	2004-01-29 15:12:08.000000000 +0100
+++ linux-2.5-hfsc/include/net/pkt_sched.h	2004-01-29 15:17:26.000000000 +0100
@@ -203,6 +203,7 @@
 
 #define PSCHED_GET_TIME(stamp) do_gettimeofday(&(stamp))
 #define PSCHED_US2JIFFIE(usecs) (((usecs)+(1000000/HZ-1))/(1000000/HZ))
+#define PSCHED_JIFFIE2US(delay) ((delay)*(1000000/HZ))
 
 #define PSCHED_EXPORTLIST EXPORT_SYMBOL(psched_tod_diff);
 
@@ -251,6 +252,7 @@
 #endif
 
 #define PSCHED_US2JIFFIE(delay) (((delay)+(1<<PSCHED_JSCALE)-1)>>PSCHED_JSCALE)
+#define PSCHED_JIFFIE2US(delay) ((delay)<<PSCHED_JSCALE)
 
 #elif PSCHED_CLOCK_SOURCE == PSCHED_CPU
 
@@ -261,6 +263,7 @@
                             EXPORT_SYMBOL(psched_clock_scale);
 
 #define PSCHED_US2JIFFIE(delay) (((delay)+psched_clock_per_hz-1)/psched_clock_per_hz)
+#define PSCHED_JIFFIE2US(delay) ((delay)*psched_clock_per_hz)
 
 #ifdef CONFIG_X86_TSC
 
diff -urN linux-2.5/net/sched/Kconfig linux-2.5-hfsc/net/sched/Kconfig
--- linux-2.5/net/sched/Kconfig	2004-01-29 15:14:02.000000000 +0100
+++ linux-2.5-hfsc/net/sched/Kconfig	2004-01-29 15:19:31.000000000 +0100
@@ -39,6 +39,16 @@
 	  To compile this code as a module, choose M here: the
 	  module will be called sch_htb.
 
+config NET_SCH_HFSC
+	tristate "HFSC packet scheduler"
+	depends on NET_SCHED
+	---help---
+	  Say Y here if you want to use the Hierarchical Fair Service Curve
+	  (HFSC) packet scheduling algorithm for some of your network devices.
+
+	  To compile this code as a module, choose M here: the
+	  module will be called sch_hfsc.
+
 config NET_SCH_CSZ
 	tristate "CSZ packet scheduler"
 	depends on NET_SCHED
@@ -55,7 +65,6 @@
 	  module will be called sch_csz.
 
 #tristate '  H-PFQ packet scheduler' CONFIG_NET_SCH_HPFQ
-#tristate '  H-FSC packet scheduler' CONFIG_NET_SCH_HFCS
 config NET_SCH_ATM
 	tristate "ATM pseudo-scheduler"
 	depends on NET_SCHED && ATM
diff -urN linux-2.5/net/sched/sch_hfsc.c linux-2.5-hfsc/net/sched/sch_hfsc.c
--- linux-2.5/net/sched/sch_hfsc.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.5-hfsc/net/sched/sch_hfsc.c	2004-01-29 15:18:27.000000000 +0100
@@ -0,0 +1,1864 @@
+/*
+ * Copyright (c) 2003 Patrick McHardy, <[email-masked]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * 2003-10-17 - Ported from altq
+ */
+/*
+ * Copyright (c) 1997-1999 Carnegie Mellon University. All Rights Reserved.
+ *
+ * Permission to use, copy, modify, and distribute this software and
+ * its documentation is hereby granted (including for commercial or
+ * for-profit use), provided that both the copyright notice and this
+ * permission notice appear in all copies of the software, derivative
+ * works, or modified versions, and any portions thereof.
+ *
+ * THIS SOFTWARE IS EXPERIMENTAL AND IS KNOWN TO HAVE BUGS, SOME OF
+ * WHICH MAY HAVE SERIOUS CONSEQUENCES.  CARNEGIE MELLON PROVIDES THIS
+ * SOFTWARE IN ITS ``AS IS'' CONDITION, AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+ * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * Carnegie Mellon encourages (but does not require) users of this
+ * software to return any improvements or extensions that they make,
+ * and to grant Carnegie Mellon the rights to redistribute these
+ * changes without encumbrance.
+ */
+/*
+ * H-FSC is described in Proceedings of SIGCOMM'97,
+ * "A Hierarchical Fair Service Curve Algorithm for Link-Sharing,
+ * Real-Time and Priority Service"
+ * by Ion Stoica, Hui Zhang, and T. S. Eugene Ng.
+ *
+ * Oleg Cherevko <[email-masked]> 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/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
+{
+	u_int64_t	sm1;	/* scaled slope of the 1st segment */
+	u_int64_t	ism1;	/* scaled inverse-slope of the 1st segment */
+	u_int64_t	dx;	/* the x-projection of the 1st segment */
+	u_int64_t	dy;	/* the y-projection of the 1st segment */
+	u_int64_t	sm2;	/* scaled slope of the 2nd segment */
+	u_int64_t	ism2;	/* scaled inverse-slope of the 2nd segment */
+};
+
+/* runtime service curve */
+struct runtime_sc
+{
+	u_int64_t	x;	/* current starting position on x-axis */
+	u_int64_t	y;	/* current starting position on y-axis */
+	u_int64_t	sm1;	/* scaled slope of the 1st segment */
+	u_int64_t	ism1;	/* scaled inverse-slope of the 1st segment */
+	u_int64_t	dx;	/* the x-projection of the 1st segment */
+	u_int64_t	dy;	/* the y-projection of the 1st segment */
+	u_int64_t	sm2;	/* scaled slope of the 2nd segment */
+	u_int64_t	ism2;	/* scaled inverse-slope of the 2nd segment */
+};
+
+enum hfsc_class_flags
+{
+	HFSC_RSC = 0x1,
+	HFSC_FSC = 0x2,
+	HFSC_USC = 0x4
+};
+
+struct hfsc_class
+{
+	u_int32_t	classid;	/* class id */
+	unsigned int	refcnt;		/* usage count */
+
+	struct tc_stats	stats;		/* generic statistics */
+	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 list_head actlist;	/* active children list */
+	struct list_head alist;		/* active children list member */
+	struct list_head ellist;	/* eligible list member */
+	struct list_head hlist;		/* hash list member */
+	struct list_head dlist;		/* drop list member */
+
+	u_int64_t	cl_total;	/* total work in bytes */
+	u_int64_t	cl_cumul;	/* cumulative work in bytes done by
+					   real-time criteria */
+
+	u_int64_t 	cl_d;		/* deadline*/
+	u_int64_t 	cl_e;		/* eligible time */
+	u_int64_t	cl_vt;		/* virtual time */
+	u_int64_t	cl_f;		/* time when this class will fit for
+					   link-sharing, max(myf, cfmin) */
+	u_int64_t	cl_myf;		/* my fit-time (calculated from this
+					   class's own upperlimit curve) */
+	u_int64_t	cl_myfadj;	/* my fit-time adjustment (to cancel
+					   history dependence) */
+	u_int64_t	cl_cfmin;	/* earliest children's fit-time (used
+					   with cl_myf to obtain cl_f) */
+	u_int64_t	cl_cvtmin;	/* minimal virtual time among the
+					   children fit for link-sharing
+					   (monotonic within a period) */
+	u_int64_t	cl_vtadj;	/* intra-period cumulative vt
+					   adjustment */
+	u_int64_t	cl_vtoff;	/* inter-period cumulative vt offset */
+	u_int64_t	cl_cvtmax;	/* max child's vt in the last period */
+
+	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
+{
+	u_int16_t	defcls;			/* default class id */
+
+	struct hfsc_class root;			/* root class */
+	struct hfsc_class *last_xmit;		/* class that transmitted last
+						   packet (for requeueing) */
+	struct list_head clhash[HFSC_HSIZE];	/* class hash */
+	struct list_head eligible;		/* eligible list */
+	struct list_head droplist;		/* active leaf class list (for
+						   dropping) */
+	struct timer_list wd_timer;		/* watchdog timer */
+};
+
+/*
+ * macros
+ */
+#if PSCHED_CLOCK_SOURCE == PSCHED_GETTIMEOFDAY
+#include <linux/time.h>
+#undef PSCHED_GET_TIME
+#define PSCHED_GET_TIME(stamp)						\
+do {									\
+	struct timeval tv;						\
+	do_gettimeofday(&tv);						\
+	(stamp) = 1000000ULL * 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 list holds backlogged classes being sorted by their eligible times.
+ * there is one eligible list per hfsc instance.
+ */
+
+static void
+ellist_insert(struct hfsc_class *cl)
+{
+	struct list_head *head = &cl->sched->eligible;
+	struct hfsc_class *p;
+
+	/* check the last entry first */
+	if (list_empty(head) ||
+	    ((p = list_entry(head->prev, struct hfsc_class, ellist)) &&
+	     p->cl_e <= cl->cl_e)) {
+		list_add_tail(&cl->ellist, head);
+		return;
+	}
+
+	list_for_each_entry(p, head, ellist) {
+		if (cl->cl_e < p->cl_e) {
+			/* insert cl before p */
+			list_add_tail(&cl->ellist, &p->ellist);
+			return;
+		}
+	}
+	ASSERT(0); /* should not reach here */
+}
+
+static inline void
+ellist_remove(struct hfsc_class *cl)
+{
+	list_del(&cl->ellist);
+}
+
+static void
+ellist_update(struct hfsc_class *cl)
+{
+	struct list_head *head = &cl->sched->eligible;
+	struct hfsc_class *p, *last;
+
+	/*
+	 * the eligible time of a class increases monotonically.
+	 * if the next entry has a larger eligible time, nothing to do.
+	 */
+	if (cl->ellist.next == head ||
+	    ((p = list_entry(cl->ellist.next, struct hfsc_class, ellist)) &&
+	     cl->cl_e <= p->cl_e))
+		return;
+
+	/* check the last entry */
+	last = list_entry(head->prev, struct hfsc_class, ellist);
+	if (last->cl_e <= cl->cl_e) {
+		list_move_tail(&cl->ellist, head);
+		return;
+	}
+
+	/*
+	 * the new position must be between the next entry
+	 * and the last entry
+	 */
+	list_for_each_entry_continue(p, head, ellist) {
+		if (cl->cl_e < p->cl_e) {
+			list_move_tail(&cl->ellist, &p->ellist);
+			return;
+		}
+	}
+	ASSERT(0); /* should not reach here */
+}
+
+/* find the class with the minimum deadline among the eligible classes */
+static inline struct hfsc_class *
+ellist_get_mindl(struct list_head *head, u_int64_t cur_time)
+{
+	struct hfsc_class *p, *cl = NULL;
+
+	list_for_each_entry(p, head, ellist) {
+		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 *
+ellist_get_minel(struct list_head *head)
+{
+	if (list_empty(head))
+		return NULL;
+	return list_entry(head->next, struct hfsc_class, ellist);
+}
+
+/*
+ * active children list holds backlogged child classes being sorted
+ * by their virtual time. each intermediate class has one active
+ * children list.
+ */
+static void
+actlist_insert(struct hfsc_class *cl)
+{
+	struct list_head *head = &cl->cl_parent->actlist;
+	struct hfsc_class *p;
+
+	/* check the last entry first */
+	if (list_empty(head) ||
+	    ((p = list_entry(head->prev, struct hfsc_class, alist)) &&
+	     p->cl_vt <= cl->cl_vt)) {
+		list_add_tail(&cl->alist, head);
+		return;
+	}
+
+	list_for_each_entry(p, head, alist) {
+		if (cl->cl_vt < p->cl_vt) {
+			/* insert cl before p */
+			list_add_tail(&cl->alist, &p->alist);
+			return;
+		}
+	}
+	ASSERT(0); /* should not reach here */
+}
+
+static inline void
+actlist_remove(struct hfsc_class *cl)
+{
+	list_del(&cl->alist);
+}
+
+static void
+actlist_update(struct hfsc_class *cl)
+{
+	struct list_head *head = &cl->cl_parent->actlist;
+	struct hfsc_class *p, *last;
+
+	/*
+	 * the virtual time of a class increases monotonically.
+	 * if the next entry has a larger virtual time, nothing to do.
+	 */
+	if (cl->alist.next == head ||
+	    ((p = list_entry(cl->alist.next, struct hfsc_class, alist)) &&
+	     cl->cl_vt <= p->cl_vt))
+		return;
+
+	/* check the last entry */
+	last = list_entry(head->prev, struct hfsc_class, alist);
+	if (last->cl_vt <= cl->cl_vt) {
+		list_move_tail(&cl->alist, head);
+		return;
+	}
+
+	/*
+	 * the new position must be between the next entry
+	 * and the last entry
+	 */
+	list_for_each_entry_continue(p, head, alist) {
+		if (cl->cl_vt < p->cl_vt) {
+			list_move_tail(&cl->alist, &p->alist);
+			return;
+		}
+	}
+	ASSERT(0); /* should not reach here */
+}
+
+static inline struct hfsc_class *
+actlist_firstfit(struct hfsc_class *cl, u_int64_t cur_time)
+{
+	struct hfsc_class *p;
+
+	list_for_each_entry(p, &cl->actlist, alist) {
+		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 *
+actlist_get_minvt(struct hfsc_class *cl, u_int64_t 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 = actlist_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;
+}
+
+/*
+ * 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
+ *
+ * Time source resolution
+ *  PSCHED_JIFFIES: for 48<=HZ<=1534 resolution is between 0.63us and 1.27us.
+ *  PSCHED_CPU: resolution is between 0.5us and 1us.
+ *  PSCHED_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 u_int64_t
+seg_x2y(u_int64_t x, u_int64_t sm)
+{
+	u_int64_t 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 u_int64_t
+seg_y2x(u_int64_t y, u_int64_t ism)
+{
+	u_int64_t 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 u_int64_t
+m2sm(u_int32_t m)
+{
+	u_int64_t sm;
+
+	sm = ((u_int64_t)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 u_int64_t
+m2ism(u_int32_t m)
+{
+	u_int64_t ism;
+
+	if (m == 0)
+		ism = HT_INFINITY;
+	else {
+		ism = ((u_int64_t)PSCHED_JIFFIE2US(HZ) << ISM_SHIFT);
+		ism += m - 1;
+		do_div(ism, m);
+	}
+	return ism;
+}
+
+/* convert d (us) into dx (psched us) */
+static u_int64_t
+d2dx(u_int32_t d)
+{
+	u_int64_t dx;
+
+	dx = ((u_int64_t)d * PSCHED_JIFFIE2US(HZ));
+	dx += 1000000 - 1;
+	do_div(dx, 1000000);
+	return dx;
+}
+
+/* convert sm (bytes/psched us) into m (bps) */
+static u_int32_t
+sm2m(u_int64_t sm)
+{
+	u_int64_t m;
+
+	m = (sm * PSCHED_JIFFIE2US(HZ)) >> SM_SHIFT;
+	return (u_int32_t)m;
+}
+
+/* convert dx (psched us) into d (us) */
+static u_int32_t
+dx2d(u_int64_t dx)
+{
+	u_int64_t d;
+
+	d = dx * 1000000;
+	do_div(d, PSCHED_JIFFIE2US(HZ));
+	return (u_int32_t)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, u_int64_t x,
+                                                            u_int64_t 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 u_int64_t
+rtsc_y2x(struct runtime_sc *rtsc, u_int64_t y)
+{
+	u_int64_t 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 u_int64_t
+rtsc_x2y(struct runtime_sc *rtsc, u_int64_t x)
+{
+	u_int64_t 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, u_int64_t x,
+                                                           u_int64_t y)
+{
+	u_int64_t y1, y2, dx, dy;
+	u_int32_t 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)
+{
+	u_int64_t 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);
+
+	ellist_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);
+
+	ellist_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 void
+update_cfmin(struct hfsc_class *cl)
+{
+	struct hfsc_class *p;
+	u_int64_t cfmin;
+
+	if (list_empty(&cl->actlist)) {
+		cl->cl_cfmin = 0;
+		return;
+	}
+	cfmin = HT_INFINITY;
+	list_for_each_entry(p, &cl->actlist, alist) {
+		if (p->cl_f == 0) {
+			cl->cl_cfmin = 0;
+			return;
+		}
+		if (p->cl_f < cfmin)
+			cfmin = p->cl_f;
+	}
+	cl->cl_cfmin = cfmin;
+}
+
+static void
+init_vf(struct hfsc_class *cl, unsigned int len)
+{
+	struct hfsc_class *max_cl, *p;
+	u_int64_t 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) {
+			if (!list_empty(&cl->cl_parent->actlist)) {
+				max_cl = list_entry(cl->cl_parent->actlist.prev,
+				                    struct hfsc_class, alist);
+				/*
+				 * 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 vtoff of children
+				 * to make a new vt (vtoff + vt) larger than
+				 * the vt in the last period for all children.
+				 */
+				vt = cl->cl_parent->cl_cvtmax;
+				list_for_each_entry(p, &cl->cl_parent->children,
+				                                       siblings)
+					p->cl_vtoff += vt;
+				cl->cl_vt = 0;
+				cl->cl_parent->cl_cvtmax = 0;
+				cl->cl_parent->cl_cvtmin = 0;
+			}
+
+			/* 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;
+
+			actlist_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;
+			update_cfmin(cl->cl_parent);
+		}
+	}
+}
+
+static void
+update_vf(struct hfsc_class *cl, unsigned int len, u_int64_t cur_time)
+{
+	u_int64_t 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 list */
+			actlist_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 list */
+		actlist_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;
+			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)
+		ellist_remove(cl);
+
+	list_del(&cl->dlist);
+
+	/*
+	 * actlist is now handled in update_vf() so that update_vf(cl, 0, 0)
+	 * needs to be called explicitly to remove a class from actlist
+	 */
+}
+
+/*
+ * 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(u_int32_t h)
+{
+	h ^= h >> 8;
+	h ^= h >> 4;
+
+	return h & (HFSC_HSIZE - 1);
+}
+
+static inline struct hfsc_class *
+hfsc_find_class(u_int32_t classid, struct Qdisc *sch)
+{
+	struct hfsc_sched *q = (struct hfsc_sched *)sch->data;
+	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,
+                u_int64_t 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,
+                u_int64_t 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, u_int32_t classid, u_int32_t parentid,
+                  struct rtattr **tca, unsigned long *arg)
+{
+	struct hfsc_sched *q = (struct hfsc_sched *)sch->data;
+	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;
+	u_int64_t cur_time;
+
+	if (opt == NULL ||
+	    rtattr_parse(tb, TCA_HFSC_MAX, RTA_DATA(opt), RTA_PAYLOAD(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]) {
+			qdisc_kill_estimator(&cl->stats);
+			qdisc_new_estimator(&cl->stats, 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);
+	INIT_LIST_HEAD(&cl->actlist);
+
+	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);
+	sch_tree_unlock(sch);
+
+#ifdef CONFIG_NET_ESTIMATOR
+	if (tca[TCA_RATE-1])
+		qdisc_new_estimator(&cl->stats, 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 = (struct hfsc_sched *)sch->data;
+
+	hfsc_destroy_filters(&cl->filter_list);
+	qdisc_destroy(cl->qdisc);
+#ifdef CONFIG_NET_ESTIMATOR
+	qdisc_kill_estimator(&cl->stats);
+#endif
+	if (cl != &q->root)
+		kfree(cl);
+}
+
+static int
+hfsc_delete_class(struct Qdisc *sch, unsigned long arg)
+{
+	struct hfsc_sched *q = (struct hfsc_sched *)sch->data;
+	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 (q->last_xmit == cl)
+		q->last_xmit = NULL;
+
+	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)
+{
+	struct hfsc_sched *q = (struct hfsc_sched *)sch->data;
+	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;
+
+	tcf = q->root.filter_list;
+	while (tcf && (result = tc_classify(skb, tcf, &res)) >= 0) {
+#ifdef 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, u_int32_t 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, u_int32_t 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 = (struct hfsc_sched *)sch->data;
+	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 inline int
+hfsc_dump_stats(struct sk_buff *skb, struct hfsc_class *cl)
+{
+	cl->stats.qlen = cl->qdisc->q.qlen;
+	if (qdisc_copy_stats(skb, &cl->stats) < 0)
+		goto rtattr_failure;
+
+	return skb->len;
+
+ rtattr_failure:
+	return -1;
+}
+
+static inline int
+hfsc_dump_xstats(struct sk_buff *skb, struct hfsc_class *cl)
+{
+	struct tc_hfsc_stats xstats;
+
+	xstats.level  = cl->level;
+	xstats.period = cl->cl_vtperiod;
+	xstats.work   = cl->cl_total;
+	xstats.rtwork = cl->cl_cumul;
+	RTA_PUT(skb, TCA_XSTATS, sizeof(xstats), &xstats);
+
+	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;
+
+	if ((hfsc_dump_stats(skb, cl) < 0) ||
+	    (hfsc_dump_xstats(skb, cl) < 0))
+		goto rtattr_failure;
+
+	return skb->len;
+
+ rtattr_failure:
+	skb_trim(skb, b - skb->data);
+	return -1;
+}
+
+static void
+hfsc_walk(struct Qdisc *sch, struct qdisc_walker *arg)
+{
+	struct hfsc_sched *q = (struct hfsc_sched *)sch->data;
+	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, u_int64_t cur_time)
+{
+	struct hfsc_sched *q = (struct hfsc_sched *)sch->data;
+	struct hfsc_class *cl;
+	u_int64_t next_time = 0;
+	long delay;
+
+	if ((cl = ellist_get_minel(&q->eligible)) != 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 = (struct hfsc_sched *)sch->data;
+	struct tc_hfsc_qopt *qopt;
+	unsigned int i;
+
+	if (opt == NULL || RTA_PAYLOAD(opt) < sizeof(*qopt))
+		return -EINVAL;
+	qopt = RTA_DATA(opt);
+
+	memset(q, 0, sizeof(struct hfsc_sched));
+	sch->stats.lock = &sch->dev->queue_lock;
+
+	q->defcls = qopt->defcls;
+	for (i = 0; i < HFSC_HSIZE; i++)
+		INIT_LIST_HEAD(&q->clhash[i]);
+	INIT_LIST_HEAD(&q->eligible);
+	INIT_LIST_HEAD(&q->droplist);
+
+	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);
+	INIT_LIST_HEAD(&q->root.actlist);
+
+	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 = (struct hfsc_sched *)sch->data;
+	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_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;
+	INIT_LIST_HEAD(&cl->actlist);
+	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 = (struct hfsc_sched *)sch->data;
+	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);
+	}
+
+	INIT_LIST_HEAD(&q->eligible);
+	INIT_LIST_HEAD(&q->droplist);
+	q->last_xmit = NULL;
+	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 = (struct hfsc_sched *)sch->data;
+	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);
+	}
+
+	del_timer(&q->wd_timer);
+}
+
+static int
+hfsc_dump_qdisc(struct Qdisc *sch, struct sk_buff *skb)
+{
+	struct hfsc_sched *q = (struct hfsc_sched *)sch->data;
+	unsigned char *b = skb->tail;
+	struct tc_hfsc_qopt qopt;
+
+	qopt.defcls = q->defcls;
+	RTA_PUT(skb, TCA_OPTIONS, sizeof(qopt), &qopt);
+
+	sch->stats.qlen = sch->q.qlen;
+	if (qdisc_copy_stats(skb, &sch->stats) < 0)
+		goto rtattr_failure;
+
+	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 = hfsc_classify(skb, sch);
+	unsigned int len = skb->len;
+	int err;
+
+	if (cl == NULL) {
+		kfree_skb(skb);
+		sch->stats.drops++;
+		return NET_XMIT_DROP;
+	}
+
+	err = cl->qdisc->enqueue(skb, cl->qdisc);
+	if (unlikely(err != NET_XMIT_SUCCESS)) {
+		cl->stats.drops++;
+		sch->stats.drops++;
+		return err;
+	}
+
+	if (cl->qdisc->q.qlen == 1)
+		set_active(cl, len);
+
+	cl->stats.packets++;
+	cl->stats.bytes += len;
+	sch->stats.packets++;
+	sch->stats.bytes += len;
+	sch->q.qlen++;
+
+	return NET_XMIT_SUCCESS;
+}
+
+static struct sk_buff *
+hfsc_dequeue(struct Qdisc *sch)
+{
+	struct hfsc_sched *q = (struct hfsc_sched *)sch->data;
+	struct hfsc_class *cl;
+	struct sk_buff *skb;
+	u_int64_t cur_time;
+	unsigned int next_len;
+	int realtime = 0;
+
+	if (sch->q.qlen == 0)
+		return NULL;
+
+	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 = ellist_get_mindl(&q->eligible, cur_time)) != NULL) {
+		realtime = 1;
+	} else {
+		/*
+		 * use link-sharing criteria
+		 * get the class with the minimum vt in the hierarchy
+		 */
+		cl = actlist_get_minvt(&q->root, cur_time);
+		if (cl == NULL) {
+			sch->stats.overlimits++;
+			if (!netif_queue_stopped(sch->dev))
+				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);
+	}
+
+	q->last_xmit = cl;
+	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 = (struct hfsc_sched *)sch->data;
+	struct hfsc_class *cl = q->last_xmit;
+	unsigned int len = skb->len;
+	int ret;
+
+	if (cl == NULL) {
+		kfree_skb(skb);
+		sch->stats.drops++;
+		return NET_XMIT_DROP;
+	}
+
+	ret = cl->qdisc->ops->requeue(skb, cl->qdisc);
+	if (ret == NET_XMIT_SUCCESS) {
+		if (cl->qdisc->q.qlen == 1)
+			set_active(cl, len);
+		sch->q.qlen++;
+	} else {
+		cl->stats.drops++;
+		sch->stats.drops++;
+	}
+	q->last_xmit = NULL;
+
+	return ret;
+}
+
+static unsigned int
+hfsc_drop(struct Qdisc *sch)
+{
+	struct hfsc_sched *q = (struct hfsc_sched *)sch->data;
+	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->stats.drops++;
+			sch->stats.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,
+	.walk		= hfsc_walk
+};
+
+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);