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[PATCH 2.4]: HFSC packet scheduler

To: "David S. Miller" <davem@xxxxxxxxxx>
Subject: [PATCH 2.4]: HFSC packet scheduler
From: Patrick McHardy <kaber@xxxxxxxxx>
Date: Thu, 29 Jan 2004 16:16:25 +0100
Cc: netdev@xxxxxxxxxxx, linux-net@xxxxxxxxxxxxxxx
Sender: netdev-bounce@xxxxxxxxxxx
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.5) Gecko/20031107 Debian/1.5-3
This is the 2.4 version of HFSC. Besides HFSC, it adds the
list_for_each_entry_continue macro from 2.6.

Best regards,
Patrick
diff -urN linux-2.4/Documentation/Configure.help 
linux-2.4-hfsc/Documentation/Configure.help
--- linux-2.4/Documentation/Configure.help      2004-01-29 15:01:26.000000000 
+0100
+++ linux-2.4-hfsc/Documentation/Configure.help 2004-01-29 15:02:35.000000000 
+0100
@@ -10647,6 +10647,15 @@
   whenever you want).  If you want to compile it as a module, say M
   here and read <file:Documentation/modules.txt>.
 
+CONFIG_NET_SCH_HFSC
+  Say Y here if you want to use the Hierarchical Fair Service Curve
+  (HFSC) packet scheduling algorithm for some of your network devices.
+
+  This code is also available as a module called sch_hfsc.o ( = code
+  which can be inserted in and removed from the running kernel
+  whenever you want).  If you want to compile it as a module, say M
+  here and read <file:Documentation/modules.txt>.
+
 CSZ packet scheduler
 CONFIG_NET_SCH_CSZ
   Say Y here if you want to use the Clark-Shenker-Zhang (CSZ) packet
diff -urN linux-2.4/include/linux/list.h linux-2.4-hfsc/include/linux/list.h
--- linux-2.4/include/linux/list.h      2004-01-29 14:59:37.000000000 +0100
+++ linux-2.4-hfsc/include/linux/list.h 2004-01-29 15:02:10.000000000 +0100
@@ -240,6 +240,20 @@
             &pos->member != (head);                                    \
             pos = n, n = list_entry(n->member.next, typeof(*n), member))
 
+/**
+ * list_for_each_entry_continue -       iterate over list of given type
+ *                      continuing after existing point
+ * @pos:        the type * to use as a loop counter.
+ * @head:       the head for your list.
+ * @member:     the name of the list_struct within the struct.
+ */
+#define list_for_each_entry_continue(pos, head, member)                        
\
+       for (pos = list_entry(pos->member.next, typeof(*pos), member),  \
+                    prefetch(pos->member.next);                        \
+            &pos->member != (head);                                    \
+            pos = list_entry(pos->member.next, typeof(*pos), member),  \
+                    prefetch(pos->member.next))
+
 #endif /* __KERNEL__ || _LVM_H_INCLUDE */
 
 #endif
diff -urN linux-2.4/include/linux/pkt_sched.h 
linux-2.4-hfsc/include/linux/pkt_sched.h
--- linux-2.4/include/linux/pkt_sched.h 2004-01-29 15:01:06.000000000 +0100
+++ linux-2.4-hfsc/include/linux/pkt_sched.h    2004-01-29 15:02:29.000000000 
+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-2.4/include/net/pkt_sched.h 
linux-2.4-hfsc/include/net/pkt_sched.h
--- linux-2.4/include/net/pkt_sched.h   2004-01-29 14:59:59.000000000 +0100
+++ linux-2.4-hfsc/include/net/pkt_sched.h      2004-01-29 15:02:12.000000000 
+0100
@@ -198,6 +198,7 @@
 
 #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);
 
@@ -246,6 +247,7 @@
 #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
 
@@ -256,6 +258,7 @@
                             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-2.4/net/sched/Config.in linux-2.4-hfsc/net/sched/Config.in
--- linux-2.4/net/sched/Config.in       2004-01-29 14:59:34.000000000 +0100
+++ linux-2.4-hfsc/net/sched/Config.in  2004-01-29 15:02:09.000000000 +0100
@@ -5,7 +5,7 @@
 tristate '  HTB packet scheduler' CONFIG_NET_SCH_HTB
 tristate '  CSZ packet scheduler' CONFIG_NET_SCH_CSZ
 #tristate '  H-PFQ packet scheduler' CONFIG_NET_SCH_HPFQ
-#tristate '  H-FSC packet scheduler' CONFIG_NET_SCH_HFCS
+tristate '  H-FSC packet scheduler' CONFIG_NET_SCH_HFSC
 if [ "$CONFIG_ATM" = "y" -o "$CONFIG_ATM" = "m" ]; then
    dep_tristate '  ATM pseudo-scheduler' CONFIG_NET_SCH_ATM $CONFIG_ATM
 fi
diff -urN linux-2.4/net/sched/sch_hfsc.c linux-2.4-hfsc/net/sched/sch_hfsc.c
--- linux-2.4/net/sched/sch_hfsc.c      1970-01-01 01:00:00.000000000 +0100
+++ linux-2.4-hfsc/net/sched/sch_hfsc.c 2004-01-29 15:02:14.000000000 +0100
@@ -0,0 +1,1864 @@
+/*
+ * Copyright (c) 2003 Patrick McHardy, <kaber@xxxxxxxxx>
+ *
+ * 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@xxxxxxxxxxxx> 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/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;
+
+       MOD_INC_USE_COUNT;
+       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);
+       MOD_DEC_USE_COUNT;
+}
+
+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)
+};
+
+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);
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