PKT SCHED: Add HTB scheduler.

net/sched/sch_htb.c

+/* vim: ts=8 sw=8
+ * net/sched/sch_htb.c	Hierarchical token bucket, feed tree version
+ *
+ *		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.
+ *
+ * Authors:	Martin Devera, <devik@cdi.cz>
+ *
+ * Credits (in time order) for older HTB versions:
+ *		Ondrej Kraus, <krauso@barr.cz> 
+ *			found missing INIT_QDISC(htb)
+ *		Vladimir Smelhaus, Aamer Akhter, Bert Hubert
+ *			helped a lot to locate nasty class stall bug
+ *		Andi Kleen, Jamal Hadi, Bert Hubert
+ *			code review and helpful comments on shaping
+ *		and many others. thanks.
+ *
+ * $Id: sch_htb.c,v 1.13 2002/05/25 09:04:50 devik Exp $
+ */
+#include <linux/config.h>
+#include <linux/module.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <asm/bitops.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/version.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/socket.h>
+#include <linux/sockios.h>
+#include <linux/in.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/if_ether.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/notifier.h>
+#include <net/ip.h>
+#include <net/route.h>
+#include <linux/skbuff.h>
+#include <linux/list.h>
+#include <linux/compiler.h>
+#include <net/sock.h>
+#include <net/pkt_sched.h>
+#include <linux/rbtree.h>
+
+/* HTB algorithm.
+    Author: devik@cdi.cz
+    ========================================================================
+    HTB is like TBF with multiple classes. It is also similar to CBQ because
+    it allows to assign priority to each class in hierarchy. 
+    In fact it is another implementation of Floyd's formal sharing.
+
+    Levels:
+    Each class is assigned level. Leaf has ALWAYS level 0 and root 
+    classes have level TC_HTB_MAXDEPTH-1. Interior nodes has level
+    one less than their parent.
+*/
+
+#define HTB_HSIZE 16	/* classid hash size */
+#define HTB_EWMAC 2	/* rate average over HTB_EWMAC*HTB_HSIZE sec */
+#define HTB_DEBUG 1	/* compile debugging support (activated by tc tool) */
+#define HTB_RATECM 1    /* whether to use rate computer */
+#define HTB_HYSTERESIS 1/* whether to use mode hysteresis for speedup */
+#define HTB_QLOCK(S) spin_lock_bh(&(S)->dev->queue_lock)
+#define HTB_QUNLOCK(S) spin_unlock_bh(&(S)->dev->queue_lock)
+#define HTB_VER 0x30006	/* major must be matched with number suplied by TC as version */
+
+#if HTB_VER >> 16 != TC_HTB_PROTOVER
+#error "Mismatched sch_htb.c and pkt_sch.h"
+#endif
+
+/* temporary debug defines to be removed after beta stage */
+#define DEVIK_MEND(N)
+#define DEVIK_MSTART(N)
+
+/* debugging support; S is subsystem, these are defined:
+  0 - netlink messages
+  1 - enqueue
+  2 - drop & requeue
+  3 - dequeue main
+  4 - dequeue one prio DRR part
+  5 - dequeue class accounting
+  6 - class overlimit status computation
+  7 - hint tree
+  8 - event queue
+ 10 - rate estimator
+ 11 - classifier 
+ 12 - fast dequeue cache
+
+ L is level; 0 = none, 1 = basic info, 2 = detailed, 3 = full
+ q->debug uint32 contains 16 2-bit fields one for subsystem starting
+ from LSB
+ */
+#ifdef HTB_DEBUG
+#define HTB_DBG(S,L,FMT,ARG...) if (((q->debug>>(2*S))&3) >= L) \
+	printk(KERN_DEBUG FMT,##ARG)
+#define HTB_CHCL(cl) BUG_TRAP((cl)->magic == HTB_CMAGIC)
+#define HTB_PASSQ q,
+#define HTB_ARGQ struct htb_sched *q,
+#define static
+#define __inline__
+#define inline
+#define HTB_CMAGIC 0xFEFAFEF1
+#define htb_safe_rb_erase(N,R) do { BUG_TRAP((N)->rb_color != -1); \
+		if ((N)->rb_color == -1) break; \
+		rb_erase(N,R); \
+		(N)->rb_color = -1; } while (0)
+#else
+#define HTB_DBG(S,L,FMT,ARG...)
+#define HTB_PASSQ
+#define HTB_ARGQ
+#define HTB_CHCL(cl)
+#define htb_safe_rb_erase(N,R) rb_erase(N,R)
+#endif
+
+
+/* used internaly to keep status of single class */
+enum htb_cmode {
+    HTB_CANT_SEND,		/* class can't send and can't borrow */
+    HTB_MAY_BORROW,		/* class can't send but may borrow */
+    HTB_CAN_SEND		/* class can send */
+};
+
+/* interior & leaf nodes; props specific to leaves are marked L: */
+struct htb_class
+{
+#ifdef HTB_DEBUG
+	unsigned magic;
+#endif
+    /* general class parameters */
+    u32 classid;
+    struct tc_stats	stats;	/* generic stats */
+    struct tc_htb_xstats xstats;/* our special stats */
+    int refcnt;			/* usage count of this class */
+
+#ifdef HTB_RATECM
+    /* rate measurement counters */
+    unsigned long rate_bytes,sum_bytes;
+    unsigned long rate_packets,sum_packets;
+#endif
+
+    /* topology */
+    int level;			/* our level (see above) */
+    struct htb_class *parent;	/* parent class */
+    struct list_head hlist;	/* classid hash list item */
+    struct list_head sibling;	/* sibling list item */
+    struct list_head children;	/* children list */
+
+    union {
+	    struct htb_class_leaf {
+		    struct Qdisc *q;
+		    int prio;
+		    int aprio;	
+		    int quantum;
+		    int deficit[TC_HTB_MAXDEPTH];
+		    struct list_head drop_list;
+	    } leaf;
+	    struct htb_class_inner {
+		    rb_root_t feed[TC_HTB_NUMPRIO];	/* feed trees */
+		    rb_node_t *ptr[TC_HTB_NUMPRIO];	/* current class ptr */
+	    } inner;
+    } un;
+    rb_node_t node[TC_HTB_NUMPRIO];	/* node for self or feed tree */
+    rb_node_t pq_node;			/* node for event queue */
+    unsigned long pq_key;	/* the same type as jiffies global */
+    
+    int prio_activity;		/* for which prios are we active */
+    enum htb_cmode cmode;	/* current mode of the class */
+
+    /* class attached filters */
+    struct tcf_proto *filter_list;
+    int filter_cnt;
+
+    int warned;		/* only one warning about non work conserving .. */
+
+    /* token bucket parameters */
+    struct qdisc_rate_table *rate;	/* rate table of the class itself */
+    struct qdisc_rate_table *ceil;	/* ceiling rate (limits borrows too) */
+    long buffer,cbuffer;		/* token bucket depth/rate */
+    long mbuffer;			/* max wait time */
+    long tokens,ctokens;		/* current number of tokens */
+    psched_time_t t_c;			/* checkpoint time */
+};
+
+/* TODO: maybe compute rate when size is too large .. or drop ? */
+static __inline__ long L2T(struct htb_class *cl,struct qdisc_rate_table *rate,
+	int size)
+{ 
+    int slot = size >> rate->rate.cell_log;
+    if (slot > 255) {
+	cl->xstats.giants++;
+	slot = 255;
+    }
+    return rate->data[slot];
+}
+
+struct htb_sched
+{
+    struct list_head root;			/* root classes list */
+    struct list_head hash[HTB_HSIZE];		/* hashed by classid */
+    struct list_head drops[TC_HTB_NUMPRIO];	/* active leaves (for drops) */
+    
+    /* self list - roots of self generating tree */
+    rb_root_t row[TC_HTB_MAXDEPTH][TC_HTB_NUMPRIO];
+    int row_mask[TC_HTB_MAXDEPTH];
+    rb_node_t *ptr[TC_HTB_MAXDEPTH][TC_HTB_NUMPRIO];
+
+    /* self wait list - roots of wait PQs per row */
+    rb_root_t wait_pq[TC_HTB_MAXDEPTH];
+
+    /* time of nearest event per level (row) */
+    unsigned long near_ev_cache[TC_HTB_MAXDEPTH];
+
+    /* whether we hit non-work conserving class during this dequeue; we use */
+    int nwc_hit;	/* this to disable mindelay complaint in dequeue */
+
+    int defcls;		/* class where unclassified flows go to */
+    u32 debug;		/* subsystem debug levels */
+
+    /* filters for qdisc itself */
+    struct tcf_proto *filter_list;
+    int filter_cnt;
+
+    int rate2quantum;		/* quant = rate / rate2quantum */
+    psched_time_t now;		/* cached dequeue time */
+    struct timer_list timer;	/* send delay timer */
+#ifdef HTB_RATECM
+    struct timer_list rttim;	/* rate computer timer */
+    int recmp_bucket;		/* which hash bucket to recompute next */
+#endif
+    
+    /* non shaped skbs; let them go directly thru */
+    struct sk_buff_head direct_queue;
+    int direct_qlen;  /* max qlen of above */
+
+    long direct_pkts;
+};
+
+/* compute hash of size HTB_HSIZE for given handle */
+static __inline__ int htb_hash(u32 h) 
+{
+#if HTB_HSIZE != 16
+ #error "Declare new hash for your HTB_HSIZE"
+#endif
+    h ^= h>>8;	/* stolen from cbq_hash */
+    h ^= h>>4;
+    return h & 0xf;
+}
+
+/* find class in global hash table using given handle */
+static __inline__ struct htb_class *htb_find(u32 handle, struct Qdisc *sch)
+{
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+	struct list_head *p;
+	if (TC_H_MAJ(handle) != sch->handle) 
+		return NULL;
+	
+	list_for_each (p,q->hash+htb_hash(handle)) {
+		struct htb_class *cl = list_entry(p,struct htb_class,hlist);
+		if (cl->classid == handle)
+			return cl;
+	}
+	return NULL;
+}
+
+/**
+ * htb_classify - classify a packet into class
+ *
+ * It returns NULL if the packet should be dropped or -1 if the packet
+ * should be passed directly thru. In all other cases leaf class is returned.
+ * We allow direct class selection by classid in priority. The we examine
+ * filters in qdisc and in inner nodes (if higher filter points to the inner
+ * node). If we end up with classid MAJOR:0 we enqueue the skb into special
+ * internal fifo (direct). These packets then go directly thru. If we still 
+ * have no valid leaf we try to use MAJOR:default leaf. It still unsuccessfull
+ * then finish and return direct queue.
+ */
+#define HTB_DIRECT (struct htb_class*)-1
+static struct htb_class *htb_classify(struct sk_buff *skb, struct Qdisc *sch)
+{
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+	struct htb_class *cl;
+	struct tcf_result res;
+	struct tcf_proto *tcf;
+	int result;
+
+	/* allow to select class by setting skb->priority to valid classid;
+	   note that nfmark can be used too by attaching filter fw with no
+	   rules in it */
+	if (skb->priority == sch->handle)
+		return HTB_DIRECT;  /* X:0 (direct flow) selected */
+	if ((cl = htb_find(skb->priority,sch)) != NULL) 
+		return cl;
+
+	tcf = q->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 = (void*)res.class) == NULL) {
+			if (res.classid == sch->handle)
+				return HTB_DIRECT;  /* X:0 (direct flow) */
+			if ((cl = htb_find(res.classid,sch)) == NULL)
+				break; /* filter selected invalid classid */
+		}
+		if (!cl->level)
+			return cl; /* we hit leaf; return it */
+
+		/* we have got inner class; apply inner filter chain */
+		tcf = cl->filter_list;
+	}
+	/* classification failed; try to use default class */
+	cl = htb_find(TC_H_MAKE(TC_H_MAJ(sch->handle),q->defcls),sch);
+	if (!cl || cl->level)
+		return HTB_DIRECT; /* bad default .. this is safe bet */
+	return cl;
+}
+
+#ifdef HTB_DEBUG
+static void htb_next_rb_node(rb_node_t **n);
+#define HTB_DUMTREE(root,memb) if(root) { \
+	rb_node_t *n = (root)->rb_node; \
+	while (n->rb_left) n = n->rb_left; \
+	while (n) { \
+		struct htb_class *cl = rb_entry(n, struct htb_class, memb); \
+		printk(" %x",cl->classid); htb_next_rb_node (&n); \
+	} }
+
+static void htb_debug_dump (struct htb_sched *q)
+{
+	int i,p;
+	printk(KERN_DEBUG "htb*g j=%lu\n",jiffies);
+	/* rows */
+	for (i=TC_HTB_MAXDEPTH-1;i>=0;i--) {
+		printk(KERN_DEBUG "htb*r%d m=%x",i,q->row_mask[i]);
+		for (p=0;p<TC_HTB_NUMPRIO;p++) {
+			if (!q->row[i][p].rb_node) continue;
+			printk(" p%d:",p);
+			HTB_DUMTREE(q->row[i]+p,node[p]);
+		}
+		printk("\n");
+	}
+	/* classes */
+	for (i = 0; i < HTB_HSIZE; i++) {
+		struct list_head *l;
+		list_for_each (l,q->hash+i) {
+			struct htb_class *cl = list_entry(l,struct htb_class,hlist);
+			long diff = PSCHED_TDIFF_SAFE(q->now, cl->t_c, (u32)cl->mbuffer, 0);
+			printk(KERN_DEBUG "htb*c%x m=%d t=%ld c=%ld pq=%lu df=%ld ql=%d "
+					"pa=%x f:",
+				cl->classid,cl->cmode,cl->tokens,cl->ctokens,
+				cl->pq_node.rb_color==-1?0:cl->pq_key,diff,
+				cl->level?0:cl->un.leaf.q->q.qlen,cl->prio_activity);
+			if (cl->level)
+			for (p=0;p<TC_HTB_NUMPRIO;p++) {
+				if (!cl->un.inner.feed[p].rb_node) continue;
+				printk(" p%d a=%x:",p,cl->un.inner.ptr[p]?rb_entry(cl->un.inner.ptr[p], struct htb_class,node[p])->classid:0);
+				HTB_DUMTREE(cl->un.inner.feed+p,node[p]);
+			}
+			printk("\n");
+		}
+	}
+}
+#endif
+/**
+ * htb_add_to_id_tree - adds class to the round robin list
+ *
+ * Routine adds class to the list (actually tree) sorted by classid.
+ * Make sure that class is not already on such list for given prio.
+ */
+static void htb_add_to_id_tree (HTB_ARGQ rb_root_t *root,
+		struct htb_class *cl,int prio)
+{
+	rb_node_t **p = &root->rb_node, *parent = NULL;
+	HTB_DBG(7,3,"htb_add_id_tree cl=%X prio=%d\n",cl->classid,prio);
+#ifdef HTB_DEBUG
+	if (cl->node[prio].rb_color != -1) { BUG_TRAP(0); return; }
+	HTB_CHCL(cl);
+	if (*p) {
+		struct htb_class *x = rb_entry(*p,struct htb_class,node[prio]);
+		HTB_CHCL(x);
+	}
+#endif
+	while (*p) {
+		struct htb_class *c; parent = *p;
+		c = rb_entry(parent, struct htb_class, node[prio]);
+		HTB_CHCL(c);
+		if (cl->classid > c->classid)
+			p = &parent->rb_right;
+		else 
+			p = &parent->rb_left;
+	}
+	rb_link_node(&cl->node[prio], parent, p);
+	rb_insert_color(&cl->node[prio], root);
+}
+
+/**
+ * htb_add_to_wait_tree - adds class to the event queue with delay
+ *
+ * The class is added to priority event queue to indicate that class will
+ * change its mode in cl->pq_key microseconds. Make sure that class is not
+ * already in the queue.
+ */
+static void htb_add_to_wait_tree (struct htb_sched *q,
+		struct htb_class *cl,long delay,int debug_hint)
+{
+	rb_node_t **p = &q->wait_pq[cl->level].rb_node, *parent = NULL;
+	HTB_DBG(7,3,"htb_add_wt cl=%X key=%lu\n",cl->classid,cl->pq_key);
+#ifdef HTB_DEBUG
+	if (cl->pq_node.rb_color != -1) { BUG_TRAP(0); return; }
+	HTB_CHCL(cl);
+	if ((delay <= 0 || delay > cl->mbuffer) && net_ratelimit())
+		printk(KERN_ERR "HTB: suspicious delay in wait_tree d=%ld cl=%X h=%d\n",delay,cl->classid,debug_hint);
+#endif
+	DEVIK_MSTART(9);
+	cl->pq_key = jiffies + PSCHED_US2JIFFIE(delay);
+	if (cl->pq_key == jiffies)
+		cl->pq_key++;
+
+	/* update the nearest event cache */
+	if (q->near_ev_cache[cl->level] - cl->pq_key < 0x80000000)
+		q->near_ev_cache[cl->level] = cl->pq_key;
+	
+	while (*p) {
+		struct htb_class *c; parent = *p;
+		c = rb_entry(parent, struct htb_class, pq_node);
+		if (cl->pq_key - c->pq_key < 0x80000000)
+			p = &parent->rb_right;
+		else 
+			p = &parent->rb_left;
+	}
+	rb_link_node(&cl->pq_node, parent, p);
+	rb_insert_color(&cl->pq_node, &q->wait_pq[cl->level]);
+	DEVIK_MEND(9);
+}
+
+/**
+ * htb_next_rb_node - finds next node in binary tree
+ *
+ * When we are past last key we return NULL.
+ * Average complexity is 2 steps per call.
+ */
+static void htb_next_rb_node(rb_node_t **n)
+{
+	rb_node_t *p;
+	if ((*n)->rb_right) {
+		*n = (*n)->rb_right;
+		while ((*n)->rb_left) 
+			*n = (*n)->rb_left;
+		return;
+	}
+	while ((p = (*n)->rb_parent) != NULL) {
+		if (p->rb_left == *n) break;
+		*n = p;
+	}
+	*n = p;
+}
+
+/**
+ * htb_add_class_to_row - add class to its row
+ *
+ * The class is added to row at priorities marked in mask.
+ * It does nothing if mask == 0.
+ */
+static inline void htb_add_class_to_row(struct htb_sched *q, 
+		struct htb_class *cl,int mask)
+{
+	HTB_DBG(7,2,"htb_addrow cl=%X mask=%X rmask=%X\n",
+			cl->classid,mask,q->row_mask[cl->level]);
+	HTB_CHCL(cl);
+	q->row_mask[cl->level] |= mask;
+	while (mask) {
+		int prio = ffz(~mask);
+		mask &= ~(1 << prio);
+		htb_add_to_id_tree(HTB_PASSQ q->row[cl->level]+prio,cl,prio);
+	}
+}
+
+/**
+ * htb_remove_class_from_row - removes class from its row
+ *
+ * The class is removed from row at priorities marked in mask.
+ * It does nothing if mask == 0.
+ */
+static __inline__ void htb_remove_class_from_row(struct htb_sched *q,
+		struct htb_class *cl,int mask)
+{
+	int m = 0;
+	HTB_CHCL(cl);
+	while (mask) {
+		int prio = ffz(~mask);
+		mask &= ~(1 << prio);
+		if (q->ptr[cl->level][prio] == cl->node+prio)
+			htb_next_rb_node(q->ptr[cl->level]+prio);
+		htb_safe_rb_erase(cl->node + prio,q->row[cl->level]+prio);
+		if (!q->row[cl->level][prio].rb_node) 
+			m |= 1 << prio;
+	}
+	HTB_DBG(7,2,"htb_delrow cl=%X mask=%X rmask=%X maskdel=%X\n",
+			cl->classid,mask,q->row_mask[cl->level],m);
+	q->row_mask[cl->level] &= ~m;
+}
+
+/**
+ * htb_activate_prios - creates active classe's feed chain
+ *
+ * The class is connected to ancestors and/or appropriate rows
+ * for priorities it is participating on. cl->cmode must be new 
+ * (activated) mode. It does nothing if cl->prio_activity == 0.
+ */
+static void htb_activate_prios(struct htb_sched *q,struct htb_class *cl)
+{
+	struct htb_class *p = cl->parent;
+	long m,mask = cl->prio_activity;
+	HTB_DBG(7,2,"htb_act_prios cl=%X mask=%lX cmode=%d\n",cl->classid,mask,cl->cmode);
+	HTB_CHCL(cl);
+
+	while (cl->cmode == HTB_MAY_BORROW && p && mask) {
+		HTB_CHCL(p);
+		m = mask; while (m) {
+			int prio = ffz(~m);
+			m &= ~(1 << prio);
+			
+			if (p->un.inner.feed[prio].rb_node)
+				/* parent already has its feed in use so that
+				   reset bit in mask as parent is already ok */
+				mask &= ~(1 << prio);
+			
+			htb_add_to_id_tree(HTB_PASSQ p->un.inner.feed+prio,cl,prio);
+		}
+		HTB_DBG(7,3,"htb_act_pr_aft p=%X pact=%X mask=%lX pmode=%d\n",
+				p->classid,p->prio_activity,mask,p->cmode);
+		p->prio_activity |= mask;
+		cl = p; p = cl->parent;
+		HTB_CHCL(cl);
+	}
+	if (cl->cmode == HTB_CAN_SEND && mask)
+		htb_add_class_to_row(q,cl,mask);
+}
+
+/**
+ * htb_deactivate_prios - remove class from feed chain
+ *
+ * cl->cmode must represent old mode (before deactivation). It does 
+ * nothing if cl->prio_activity == 0. Class is removed from all feed
+ * chains and rows.
+ */
+static void htb_deactivate_prios(struct htb_sched *q, struct htb_class *cl)
+{
+	struct htb_class *p = cl->parent;
+	long m,mask = cl->prio_activity;
+	HTB_DBG(7,2,"htb_deact_prios cl=%X mask=%lX cmode=%d\n",cl->classid,mask,cl->cmode);
+	HTB_CHCL(cl);
+
+	while (cl->cmode == HTB_MAY_BORROW && p && mask) {
+		m = mask; mask = 0; 
+		while (m) {
+			int prio = ffz(~m);
+			m &= ~(1 << prio);
+			
+			if (p->un.inner.ptr[prio] == cl->node+prio)
+				htb_next_rb_node(p->un.inner.ptr + prio);
+			
+			htb_safe_rb_erase(cl->node + prio,p->un.inner.feed + prio);
+			
+			if (!p->un.inner.feed[prio].rb_node) 
+				mask |= 1 << prio;
+		}
+		HTB_DBG(7,3,"htb_deact_pr_aft p=%X pact=%X mask=%lX pmode=%d\n",
+				p->classid,p->prio_activity,mask,p->cmode);
+		p->prio_activity &= ~mask;
+		cl = p; p = cl->parent;
+		HTB_CHCL(cl);
+	}
+	if (cl->cmode == HTB_CAN_SEND && mask) 
+		htb_remove_class_from_row(q,cl,mask);
+}
+
+/**
+ * htb_class_mode - computes and returns current class mode
+ *
+ * It computes cl's mode at time cl->t_c+diff and returns it. If mode
+ * is not HTB_CAN_SEND then cl->pq_key is updated to time difference
+ * from now to time when cl will change its state. 
+ * Also it is worth to note that class mode doesn't change simply
+ * at cl->{c,}tokens == 0 but there can rather be hysteresis of 
+ * 0 .. -cl->{c,}buffer range. It is meant to limit number of
+ * mode transitions per time unit. The speed gain is about 1/6.
+ */
+static __inline__ enum htb_cmode 
+htb_class_mode(struct htb_class *cl,long *diff)
+{
+    long toks;
+
+    if ((toks = (cl->ctokens + *diff)) < (
+#ifdef HTB_HYSTERESIS
+	    cl->cmode != HTB_CANT_SEND ? -cl->cbuffer :
+#endif
+       	    0)) {
+	    *diff = -toks;
+	    return HTB_CANT_SEND;
+    }
+    if ((toks = (cl->tokens + *diff)) >= (
+#ifdef HTB_HYSTERESIS
+	    cl->cmode == HTB_CAN_SEND ? -cl->buffer :
+#endif
+	    0))
+	    return HTB_CAN_SEND;
+
+    *diff = -toks;
+    return HTB_MAY_BORROW;
+}
+
+/**
+ * htb_change_class_mode - changes classe's mode
+ *
+ * This should be the only way how to change classe's mode under normal
+ * cirsumstances. Routine will update feed lists linkage, change mode
+ * and add class to the wait event queue if appropriate. New mode should
+ * be different from old one and cl->pq_key has to be valid if changing
+ * to mode other than HTB_CAN_SEND (see htb_add_to_wait_tree).
+ */
+static void 
+htb_change_class_mode(struct htb_sched *q, struct htb_class *cl, long *diff)
+{ 
+	enum htb_cmode new_mode = htb_class_mode(cl,diff);
+	
+	HTB_CHCL(cl);
+	HTB_DBG(7,1,"htb_chging_clmode %d->%d cl=%X\n",cl->cmode,new_mode,cl->classid);
+
+	if (new_mode == cl->cmode)
+		return;	
+	
+	if (cl->prio_activity) { /* not neccessary: speed optimization */
+		if (cl->cmode != HTB_CANT_SEND) 
+			htb_deactivate_prios(q,cl);
+		cl->cmode = new_mode;
+		if (new_mode != HTB_CANT_SEND) 
+			htb_activate_prios(q,cl);
+	} else 
+		cl->cmode = new_mode;
+}
+
+/**
+ * htb_activate - inserts leaf cl into appropriate active feeds 
+ *
+ * Routine learns (new) priority of leaf and activates feed chain
+ * for the prio. It can be called on already active leaf safely.
+ * It also adds leaf into droplist.
+ */
+static __inline__ void htb_activate(struct htb_sched *q,struct htb_class *cl)
+{
+	BUG_TRAP(!cl->level && cl->un.leaf.q && cl->un.leaf.q->q.qlen);
+	HTB_CHCL(cl);
+	if (!cl->prio_activity) {
+		cl->prio_activity = 1 << (cl->un.leaf.aprio = cl->un.leaf.prio);
+		htb_activate_prios(q,cl);
+		list_add_tail(&cl->un.leaf.drop_list,q->drops+cl->un.leaf.aprio);
+	}
+}
+
+/**
+ * htb_deactivate - remove leaf cl from active feeds 
+ *
+ * Make sure that leaf is active. In the other words it can't be called
+ * with non-active leaf. It also removes class from the drop list.
+ */
+static __inline__ void 
+htb_deactivate(struct htb_sched *q,struct htb_class *cl)
+{
+	BUG_TRAP(cl->prio_activity);
+	HTB_CHCL(cl);
+	htb_deactivate_prios(q,cl);
+	cl->prio_activity = 0;
+	list_del_init(&cl->un.leaf.drop_list);
+}
+
+static int htb_enqueue(struct sk_buff *skb, struct Qdisc *sch)
+{
+    struct htb_sched *q = (struct htb_sched *)sch->data;
+    struct htb_class *cl = htb_classify(skb,sch);
+
+    DEVIK_MSTART(0);
+    if (cl == HTB_DIRECT || !cl) {
+	/* enqueue to helper queue */
+	if (q->direct_queue.qlen < q->direct_qlen && cl) {
+	    __skb_queue_tail(&q->direct_queue, skb);
+	    q->direct_pkts++;
+	} else {
+	    kfree_skb (skb);
+	    sch->stats.drops++;
+	    DEVIK_MEND(0);
+	    return NET_XMIT_DROP;
+	}
+    } else if (cl->un.leaf.q->enqueue(skb, cl->un.leaf.q) != NET_XMIT_SUCCESS) {
+	sch->stats.drops++;
+	cl->stats.drops++;
+	DEVIK_MEND(0);
+	return NET_XMIT_DROP;
+    } else {
+	cl->stats.packets++; cl->stats.bytes += skb->len;
+	DEVIK_MSTART(1);
+	htb_activate (q,cl);
+	DEVIK_MEND(1);
+    }
+
+    sch->q.qlen++;
+    sch->stats.packets++; sch->stats.bytes += skb->len;
+    HTB_DBG(1,1,"htb_enq_ok cl=%X skb=%p\n",cl?cl->classid:0,skb);
+    DEVIK_MEND(0);
+    return NET_XMIT_SUCCESS;
+}
+
+/* TODO: requeuing packet charges it to policers again !! */
+static int htb_requeue(struct sk_buff *skb, struct Qdisc *sch)
+{
+    struct htb_sched *q = (struct htb_sched *)sch->data;
+    struct htb_class *cl = htb_classify(skb,sch);
+
+    if (cl == HTB_DIRECT || !cl) {
+	/* enqueue to helper queue */
+	if (q->direct_queue.qlen < q->direct_qlen && cl) {
+	    __skb_queue_tail(&q->direct_queue, skb);
+	    q->direct_pkts++;
+	} else {
+	    kfree_skb (skb);
+	    sch->stats.drops++;
+	    return NET_XMIT_DROP;
+	}
+    } else if (cl->un.leaf.q->ops->requeue(skb, cl->un.leaf.q) != NET_XMIT_SUCCESS) {
+	sch->stats.drops++;
+	cl->stats.drops++;
+	return NET_XMIT_DROP;
+    } else 
+	    htb_activate (q,cl);
+
+    sch->q.qlen++;
+    HTB_DBG(1,1,"htb_req_ok cl=%X skb=%p\n",cl?cl->classid:0,skb);
+    return NET_XMIT_SUCCESS;
+}
+
+static void htb_timer(unsigned long arg)
+{
+    struct Qdisc *sch = (struct Qdisc*)arg;
+    sch->flags &= ~TCQ_F_THROTTLED;
+    wmb();
+    netif_schedule(sch->dev);
+}
+
+#ifdef HTB_RATECM
+#define RT_GEN(D,R) R+=D-(R/HTB_EWMAC);D=0
+static void htb_rate_timer(unsigned long arg)
+{
+	struct Qdisc *sch = (struct Qdisc*)arg;
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+	struct list_head *p;
+
+	/* lock queue so that we can muck with it */
+	HTB_QLOCK(sch);
+	HTB_DBG(10,1,"htb_rttmr j=%ld\n",jiffies);
+
+	q->rttim.expires = jiffies + HZ;
+	add_timer(&q->rttim);
+
+	/* scan and recompute one bucket at time */
+	if (++q->recmp_bucket >= HTB_HSIZE) 
+		q->recmp_bucket = 0;
+	list_for_each (p,q->hash+q->recmp_bucket) {
+		struct htb_class *cl = list_entry(p,struct htb_class,hlist);
+		HTB_DBG(10,2,"htb_rttmr_cl cl=%X sbyte=%lu spkt=%lu\n",
+				cl->classid,cl->sum_bytes,cl->sum_packets);
+		RT_GEN (cl->sum_bytes,cl->rate_bytes);
+		RT_GEN (cl->sum_packets,cl->rate_packets);
+	}
+	HTB_QUNLOCK(sch);
+}
+#endif
+
+/**
+ * htb_charge_class - charges ammount "bytes" to leaf and ancestors
+ *
+ * Routine assumes that packet "bytes" long was dequeued from leaf cl
+ * borrowing from "level". It accounts bytes to ceil leaky bucket for
+ * leaf and all ancestors and to rate bucket for ancestors at levels
+ * "level" and higher. It also handles possible change of mode resulting
+ * from the update. Note that mode can also increase here (MAY_BORROW to
+ * CAN_SEND) because we can use more precise clock that event queue here.
+ * In such case we remove class from event queue first.
+ */
+static void htb_charge_class(struct htb_sched *q,struct htb_class *cl,
+		int level,int bytes)
+{	
+	long toks,diff;
+	enum htb_cmode old_mode;
+	HTB_DBG(5,1,"htb_chrg_cl cl=%X lev=%d len=%d\n",cl->classid,level,bytes);
+
+#define HTB_ACCNT(T,B,R) toks = diff + cl->T; \
+	if (toks > cl->B) toks = cl->B; \
+	toks -= L2T(cl, cl->R, bytes); \
+	if (toks <= -cl->mbuffer) toks = 1-cl->mbuffer; \
+	cl->T = toks
+
+	while (cl) {
+		HTB_CHCL(cl);
+		diff = PSCHED_TDIFF_SAFE(q->now, cl->t_c, (u32)cl->mbuffer, 0);
+#ifdef HTB_DEBUG
+		if (diff > cl->mbuffer || diff < 0 || PSCHED_TLESS(q->now, cl->t_c)) {
+			if (net_ratelimit())
+				printk(KERN_ERR "HTB: bad diff in charge, cl=%X diff=%lX now=%Lu then=%Lu j=%lu\n",
+						cl->classid,diff,q->now,cl->t_c,jiffies);
+			diff = 1000;
+		}
+#endif
+		if (cl->level >= level) {
+			if (cl->level == level) cl->xstats.lends++;
+			HTB_ACCNT (tokens,buffer,rate);
+		} else {
+			cl->xstats.borrows++;
+			cl->tokens += diff; /* we moved t_c; update tokens */
+		}
+		HTB_ACCNT (ctokens,cbuffer,ceil);
+		cl->t_c = q->now;
+		HTB_DBG(5,2,"htb_chrg_clp cl=%X diff=%ld tok=%ld ctok=%ld\n",cl->classid,diff,cl->tokens,cl->ctokens);
+
+		old_mode = cl->cmode; diff = 0;
+		htb_change_class_mode(q,cl,&diff);
+		if (old_mode != cl->cmode) {
+			if (old_mode != HTB_CAN_SEND)
+				htb_safe_rb_erase(&cl->pq_node,q->wait_pq+cl->level);
+			if (cl->cmode != HTB_CAN_SEND)
+				htb_add_to_wait_tree (q,cl,diff,1);
+		}
+		
+#ifdef HTB_RATECM
+		/* update rate counters */
+		cl->sum_bytes += bytes; cl->sum_packets++;
+#endif
+
+		/* update byte stats except for leaves which are already updated */
+		if (cl->level) {
+			cl->stats.bytes += bytes;
+			cl->stats.packets++;
+		}
+		cl = cl->parent;
+	}
+}
+
+/**
+ * htb_do_events - make mode changes to classes at the level
+ *
+ * Scans event queue for pending events and applies them. Returns jiffies to
+ * next pending event (0 for no event in pq).
+ */
+static long htb_do_events(struct htb_sched *q,int level)
+{
+	int i;
+	HTB_DBG(8,1,"htb_do_events l=%d root=%p rmask=%X\n",
+			level,q->wait_pq[level].rb_node,q->row_mask[level]);
+	for (i = 0; i < 500; i++) {
+		struct htb_class *cl;
+		long diff;
+		rb_node_t *p = q->wait_pq[level].rb_node;
+		if (!p) return 0;
+		while (p->rb_left) p = p->rb_left;
+
+		cl = rb_entry(p, struct htb_class, pq_node);
+		if (cl->pq_key - (jiffies+1) < 0x80000000) {
+			HTB_DBG(8,3,"htb_do_ev_ret delay=%ld\n",cl->pq_key - jiffies);
+			return cl->pq_key - jiffies;
+		}
+		htb_safe_rb_erase(p,q->wait_pq+level);
+		diff = PSCHED_TDIFF_SAFE(q->now, cl->t_c, (u32)cl->mbuffer, 0);
+#ifdef HTB_DEBUG
+		if (diff > cl->mbuffer || diff < 0 || PSCHED_TLESS(q->now, cl->t_c)) {
+			if (net_ratelimit())
+				printk(KERN_ERR "HTB: bad diff in events, cl=%X diff=%lX now=%Lu then=%Lu j=%lu\n",
+						cl->classid,diff,q->now,cl->t_c,jiffies);
+			diff = 1000;
+		}
+#endif
+		htb_change_class_mode(q,cl,&diff);
+		if (cl->cmode != HTB_CAN_SEND)
+			htb_add_to_wait_tree (q,cl,diff,2);
+	}
+	if (net_ratelimit())
+		printk(KERN_WARNING "htb: too many events !\n");
+	return HZ/10;
+}
+
+/**
+ * htb_lookup_leaf - returns next leaf class in DRR order
+ *
+ * Find leaf where current feed pointers points to.
+ */
+static struct htb_class *
+htb_lookup_leaf(rb_root_t *tree,int prio,rb_node_t **pptr)
+{
+	int i;
+	struct {
+		rb_node_t *root;
+		rb_node_t **pptr;
+	} stk[TC_HTB_MAXDEPTH],*sp = stk;
+	
+	sp->root = tree->rb_node;
+	sp->pptr = pptr;
+
+	for (i = 0; i < 65535; i++) {
+		if (!*sp->pptr) { /* we are at right end; rewind & go up */
+			*sp->pptr = sp->root;
+			while ((*sp->pptr)->rb_left) 
+				*sp->pptr = (*sp->pptr)->rb_left;
+			if (sp > stk) {
+				sp--;
+				BUG_TRAP(*sp->pptr); if(!*sp->pptr) return NULL;
+				htb_next_rb_node (sp->pptr);
+			}
+		} else {
+			struct htb_class *cl;
+			cl = rb_entry(*sp->pptr,struct htb_class,node[prio]);
+			HTB_CHCL(cl);
+			if (!cl->level) 
+				return cl;
+			(++sp)->root = cl->un.inner.feed[prio].rb_node;
+			sp->pptr = cl->un.inner.ptr+prio;
+		}
+	}
+	BUG_TRAP(0);
+	return NULL;
+}
+
+/* dequeues packet at given priority and level; call only if
+   you are sure that there is active class at prio/level */
+static struct sk_buff *
+htb_dequeue_tree(struct htb_sched *q,int prio,int level)
+{
+	struct sk_buff *skb = NULL;
+	//struct htb_sched *q = (struct htb_sched *)sch->data;
+	struct htb_class *cl,*start;
+	/* look initial class up in the row */
+	DEVIK_MSTART(6);
+	start = cl = htb_lookup_leaf (q->row[level]+prio,prio,q->ptr[level]+prio);
+	
+	do {
+		BUG_TRAP(cl && cl->un.leaf.q->q.qlen); if (!cl) return NULL;
+		HTB_DBG(4,1,"htb_deq_tr prio=%d lev=%d cl=%X defic=%d\n",
+				prio,level,cl->classid,cl->un.leaf.deficit[level]);
+	
+		if (likely((skb = cl->un.leaf.q->dequeue(cl->un.leaf.q)) != NULL)) 
+			break;
+		if (!cl->warned) {
+			printk(KERN_WARNING "htb: class %X isn't work conserving ?!\n",cl->classid);
+			cl->warned = 1;
+		}
+		q->nwc_hit++;
+		htb_next_rb_node((level?cl->parent->un.inner.ptr:q->ptr[0])+prio);
+		cl = htb_lookup_leaf (q->row[level]+prio,prio,q->ptr[level]+prio);
+	} while (cl != start);
+
+	DEVIK_MEND(6);
+	DEVIK_MSTART(7);
+	if (likely(skb != NULL)) {
+		if ((cl->un.leaf.deficit[level] -= skb->len) < 0) {
+			HTB_DBG(4,2,"htb_next_cl oldptr=%p quant_add=%d\n",
+				level?cl->parent->un.inner.ptr[prio]:q->ptr[0][prio],cl->un.leaf.quantum);
+			cl->un.leaf.deficit[level] += cl->un.leaf.quantum;
+			htb_next_rb_node((level?cl->parent->un.inner.ptr:q->ptr[0])+prio);
+		}
+		/* this used to be after charge_class but this constelation
+		   gives us slightly better performance */
+		if (!cl->un.leaf.q->q.qlen)
+			htb_deactivate (q,cl);
+	DEVIK_MSTART(8);
+		htb_charge_class (q,cl,level,skb->len);
+	DEVIK_MEND(8);
+	}
+	DEVIK_MEND(7);
+	return skb;
+}
+
+static void htb_delay_by(struct Qdisc *sch,long delay)
+{
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+	if (netif_queue_stopped(sch->dev)) return;
+	if (delay <= 0) delay = 1;
+	if (unlikely(delay > 5*HZ)) {
+		if (net_ratelimit())
+			printk(KERN_INFO "HTB delay %ld > 5sec\n", delay);
+		delay = 5*HZ;
+	}
+	del_timer(&q->timer);
+	q->timer.expires = jiffies + delay;
+	add_timer(&q->timer);
+	sch->flags |= TCQ_F_THROTTLED;
+	sch->stats.overlimits++;
+	HTB_DBG(3,1,"htb_deq t_delay=%ld\n",delay);
+}
+
+static struct sk_buff *htb_dequeue(struct Qdisc *sch)
+{
+	struct sk_buff *skb = NULL;
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+	int level;
+	long min_delay;
+
+	HTB_DBG(3,1,"htb_deq dircnt=%d qlen=%d\n",skb_queue_len(&q->direct_queue),
+			sch->q.qlen);
+
+	/* try to dequeue direct packets as high prio (!) to minimize cpu work */
+	if ((skb = __skb_dequeue(&q->direct_queue)) != NULL) {
+		sch->flags &= ~TCQ_F_THROTTLED;
+		sch->q.qlen--;
+		return skb;
+	}
+
+	DEVIK_MSTART(2);
+	if (!sch->q.qlen) goto fin;
+	PSCHED_GET_TIME(q->now);
+
+	min_delay = HZ*5;
+	q->nwc_hit = 0;
+	for (level = 0; level < TC_HTB_MAXDEPTH; level++) {
+		/* common case optimization - skip event handler quickly */
+		int m;
+		long delay;
+	DEVIK_MSTART(3);
+		if (jiffies - q->near_ev_cache[level] < 0x80000000 || 0) {
+			delay = htb_do_events(q,level);
+			q->near_ev_cache[level] += delay ? delay : HZ;
+		} else
+			delay = q->near_ev_cache[level] - jiffies;	
+		
+		if (delay && min_delay > delay) 
+			min_delay = delay;
+	DEVIK_MEND(3);
+	DEVIK_MSTART(5);
+		m = ~q->row_mask[level];
+		while (m != (int)(-1)) {
+			int prio = ffz (m);
+			m |= 1 << prio;
+			skb = htb_dequeue_tree(q,prio,level);
+			if (likely(skb != NULL)) {
+				sch->q.qlen--;
+				sch->flags &= ~TCQ_F_THROTTLED;
+	DEVIK_MEND(5);
+				goto fin;
+			}
+		}
+	DEVIK_MEND(5);
+	}
+	DEVIK_MSTART(4);
+#ifdef HTB_DEBUG
+	if (!q->nwc_hit && min_delay >= 5*HZ && net_ratelimit()) { 
+		printk(KERN_ERR "HTB: mindelay=%ld, report it please !\n",min_delay);
+		htb_debug_dump(q);
+	}
+#endif
+	htb_delay_by (sch,min_delay);
+	DEVIK_MEND(4);
+fin:
+	HTB_DBG(3,1,"htb_deq_end %s j=%lu skb=%p\n",sch->dev->name,jiffies,skb);
+	DEVIK_MEND(2);
+	return skb;
+}
+
+/* try to drop from each class (by prio) until one succeed */
+static int htb_drop(struct Qdisc* sch)
+{
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+	int prio;
+
+	for (prio = TC_HTB_NUMPRIO - 1; prio >= 0; prio--) {
+		struct list_head *p;
+		list_for_each (p,q->drops+prio) {
+			struct htb_class *cl = list_entry(p,struct htb_class,
+					un.leaf.drop_list);
+			if (cl->un.leaf.q->ops->drop && 
+				cl->un.leaf.q->ops->drop(cl->un.leaf.q)) {
+				sch->q.qlen--;
+				if (!cl->un.leaf.q->q.qlen)
+					htb_deactivate (q,cl);
+				return 1;
+			}
+		}
+	}
+	return 0;
+}
+
+/* reset all classes */
+/* always caled under BH & queue lock */
+static void htb_reset(struct Qdisc* sch)
+{
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+	int i;
+	HTB_DBG(0,1,"htb_reset sch=%X, handle=%X\n",(int)sch,sch->handle);
+
+	for (i = 0; i < HTB_HSIZE; i++) {
+		struct list_head *p;
+		list_for_each (p,q->hash+i) {
+			struct htb_class *cl = list_entry(p,struct htb_class,hlist);
+			if (cl->level)
+				memset(&cl->un.inner,0,sizeof(cl->un.inner));
+			else {
+				if (cl->un.leaf.q) 
+					qdisc_reset(cl->un.leaf.q);
+				INIT_LIST_HEAD(&cl->un.leaf.drop_list);
+			}
+			cl->prio_activity = 0;
+			cl->cmode = HTB_CAN_SEND;
+#ifdef HTB_DEBUG
+			cl->pq_node.rb_color = -1;
+			memset(cl->node,255,sizeof(cl->node));
+#endif
+
+		}
+	}
+	sch->flags &= ~TCQ_F_THROTTLED;
+	del_timer(&q->timer);
+	__skb_queue_purge(&q->direct_queue);
+	sch->q.qlen = 0;
+	memset(q->row,0,sizeof(q->row));
+	memset(q->row_mask,0,sizeof(q->row_mask));
+	memset(q->wait_pq,0,sizeof(q->wait_pq));
+	memset(q->ptr,0,sizeof(q->ptr));
+	for (i = 0; i < TC_HTB_NUMPRIO; i++)
+		INIT_LIST_HEAD(q->drops+i);
+}
+
+static int htb_init(struct Qdisc *sch, struct rtattr *opt)
+{
+	struct htb_sched *q = (struct htb_sched*)sch->data;
+	struct rtattr *tb[TCA_HTB_INIT];
+	struct tc_htb_glob *gopt;
+	int i;
+#ifdef HTB_DEBUG
+	printk(KERN_INFO "HTB init, kernel part version %d.%d\n",
+			  HTB_VER >> 16,HTB_VER & 0xffff);
+#endif
+	if (!opt || rtattr_parse(tb, TCA_HTB_INIT, RTA_DATA(opt), RTA_PAYLOAD(opt)) ||
+			tb[TCA_HTB_INIT-1] == NULL ||
+			RTA_PAYLOAD(tb[TCA_HTB_INIT-1]) < sizeof(*gopt)) {
+		printk(KERN_ERR "HTB: hey probably you have bad tc tool ?\n");
+		return -EINVAL;
+	}
+	gopt = RTA_DATA(tb[TCA_HTB_INIT-1]);
+	if (gopt->version != HTB_VER >> 16) {
+		printk(KERN_ERR "HTB: need tc/htb version %d (minor is %d), you have %d\n",
+				HTB_VER >> 16,HTB_VER & 0xffff,gopt->version);
+		return -EINVAL;
+	}
+	memset(q,0,sizeof(*q));
+	q->debug = gopt->debug;
+	HTB_DBG(0,1,"htb_init sch=%p handle=%X r2q=%d\n",sch,sch->handle,gopt->rate2quantum);
+
+	INIT_LIST_HEAD(&q->root);
+	for (i = 0; i < HTB_HSIZE; i++)
+		INIT_LIST_HEAD(q->hash+i);
+	for (i = 0; i < TC_HTB_NUMPRIO; i++)
+		INIT_LIST_HEAD(q->drops+i);
+
+	init_timer(&q->timer);
+	skb_queue_head_init(&q->direct_queue);
+
+	q->direct_qlen = sch->dev->tx_queue_len;
+	q->timer.function = htb_timer;
+	q->timer.data = (unsigned long)sch;
+
+#ifdef HTB_RATECM
+	init_timer(&q->rttim);
+	q->rttim.function = htb_rate_timer;
+	q->rttim.data = (unsigned long)sch;
+	q->rttim.expires = jiffies + HZ;
+	add_timer(&q->rttim);
+#endif
+	if ((q->rate2quantum = gopt->rate2quantum) < 1)
+		q->rate2quantum = 1;
+	q->defcls = gopt->defcls;
+
+	MOD_INC_USE_COUNT;
+	return 0;
+}
+
+static int htb_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+	struct htb_sched *q = (struct htb_sched*)sch->data;
+	unsigned char	 *b = skb->tail;
+	struct rtattr *rta;
+	struct tc_htb_glob gopt;
+	HTB_DBG(0,1,"htb_dump sch=%p, handle=%X\n",sch,sch->handle);
+	/* stats */
+	HTB_QLOCK(sch);
+	gopt.direct_pkts = q->direct_pkts;
+
+#ifdef HTB_DEBUG
+	htb_debug_dump(q);
+#endif
+	gopt.version = HTB_VER;
+	gopt.rate2quantum = q->rate2quantum;
+	gopt.defcls = q->defcls;
+	gopt.debug = q->debug;
+	rta = (struct rtattr*)b;
+	RTA_PUT(skb, TCA_OPTIONS, 0, NULL);
+	RTA_PUT(skb, TCA_HTB_INIT, sizeof(gopt), &gopt);
+	rta->rta_len = skb->tail - b;
+	sch->stats.qlen = sch->q.qlen;
+	RTA_PUT(skb, TCA_STATS, sizeof(sch->stats), &sch->stats);
+	HTB_QUNLOCK(sch);
+	return skb->len;
+rtattr_failure:
+	HTB_QUNLOCK(sch);
+	skb_trim(skb, skb->tail - skb->data);
+	return -1;
+}
+
+static int htb_dump_class(struct Qdisc *sch, unsigned long arg,
+	struct sk_buff *skb, struct tcmsg *tcm)
+{
+#ifdef HTB_DEBUG
+	struct htb_sched *q = (struct htb_sched*)sch->data;
+#endif
+	struct htb_class *cl = (struct htb_class*)arg;
+	unsigned char	 *b = skb->tail;
+	struct rtattr *rta;
+	struct tc_htb_opt opt;
+
+	HTB_DBG(0,1,"htb_dump_class handle=%X clid=%X\n",sch->handle,cl->classid);
+
+	HTB_QLOCK(sch);
+	tcm->tcm_parent = cl->parent ? cl->parent->classid : TC_H_ROOT;
+	tcm->tcm_handle = cl->classid;
+	if (!cl->level && cl->un.leaf.q) {
+		tcm->tcm_info = cl->un.leaf.q->handle;
+		cl->stats.qlen = cl->un.leaf.q->q.qlen;
+	}
+
+	rta = (struct rtattr*)b;
+	RTA_PUT(skb, TCA_OPTIONS, 0, NULL);
+
+	memset (&opt,0,sizeof(opt));
+
+	opt.rate = cl->rate->rate; opt.buffer = cl->buffer;
+	opt.ceil = cl->ceil->rate; opt.cbuffer = cl->cbuffer;
+	opt.quantum = cl->un.leaf.quantum; opt.prio = cl->un.leaf.prio;
+	opt.level = cl->level; 
+	RTA_PUT(skb, TCA_HTB_PARMS, sizeof(opt), &opt);
+	rta->rta_len = skb->tail - b;
+
+#ifdef HTB_RATECM
+	cl->stats.bps = cl->rate_bytes/(HTB_EWMAC*HTB_HSIZE);
+	cl->stats.pps = cl->rate_packets/(HTB_EWMAC*HTB_HSIZE);
+#endif
+
+	cl->xstats.tokens = cl->tokens;
+	cl->xstats.ctokens = cl->ctokens;
+	RTA_PUT(skb, TCA_STATS, sizeof(cl->stats), &cl->stats);
+	RTA_PUT(skb, TCA_XSTATS, sizeof(cl->xstats), &cl->xstats);
+	HTB_QUNLOCK(sch);
+	return skb->len;
+rtattr_failure:
+	HTB_QUNLOCK(sch);
+	skb_trim(skb, b - skb->data);
+	return -1;
+}
+
+static int htb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
+	struct Qdisc **old)
+{
+	struct htb_class *cl = (struct htb_class*)arg;
+
+	if (cl && !cl->level) {
+		if (new == NULL && (new = qdisc_create_dflt(sch->dev, 
+					&pfifo_qdisc_ops)) == NULL)
+					return -ENOBUFS;
+		sch_tree_lock(sch);
+		if ((*old = xchg(&cl->un.leaf.q, new)) != NULL) {
+			/* TODO: is it correct ? Why CBQ doesn't do it ? */
+			sch->q.qlen -= (*old)->q.qlen;	
+			qdisc_reset(*old);
+		}
+		sch_tree_unlock(sch);
+		return 0;
+	}
+	return -ENOENT;
+}
+
+static struct Qdisc * htb_leaf(struct Qdisc *sch, unsigned long arg)
+{
+	struct htb_class *cl = (struct htb_class*)arg;
+	return (cl && !cl->level) ? cl->un.leaf.q : NULL;
+}
+
+static unsigned long htb_get(struct Qdisc *sch, u32 classid)
+{
+#ifdef HTB_DEBUG
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+#endif
+	struct htb_class *cl = htb_find(classid,sch);
+	HTB_DBG(0,1,"htb_get clid=%X q=%p cl=%p ref=%d\n",classid,q,cl,cl?cl->refcnt:0);
+	if (cl) 
+		cl->refcnt++;
+	return (unsigned long)cl;
+}
+
+static void htb_destroy_filters(struct tcf_proto **fl)
+{
+	struct tcf_proto *tp;
+
+	while ((tp = *fl) != NULL) {
+		*fl = tp->next;
+		tp->ops->destroy(tp);
+	}
+}
+
+static void htb_destroy_class(struct Qdisc* sch,struct htb_class *cl)
+{
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+	HTB_DBG(0,1,"htb_destrycls clid=%X ref=%d\n", cl?cl->classid:0,cl?cl->refcnt:0);
+	if (!cl->level) {
+		BUG_TRAP(cl->un.leaf.q);
+		sch->q.qlen -= cl->un.leaf.q->q.qlen;
+		qdisc_destroy(cl->un.leaf.q);
+	}
+	qdisc_put_rtab(cl->rate);
+	qdisc_put_rtab(cl->ceil);
+	
+#ifdef CONFIG_NET_ESTIMATOR
+	qdisc_kill_estimator(&cl->stats);
+#endif
+	htb_destroy_filters (&cl->filter_list);
+	
+	while (!list_empty(&cl->children)) 
+		htb_destroy_class (sch,list_entry(cl->children.next,
+					struct htb_class,sibling));
+
+	/* note: this delete may happen twice (see htb_delete) */
+	list_del(&cl->hlist);
+	list_del(&cl->sibling);
+	
+	if (cl->prio_activity)
+		htb_deactivate (q,cl);
+	
+	if (cl->cmode != HTB_CAN_SEND)
+		htb_safe_rb_erase(&cl->pq_node,q->wait_pq+cl->level);
+	
+	kfree(cl);
+}
+
+/* always caled under BH & queue lock */
+static void htb_destroy(struct Qdisc* sch)
+{
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+	HTB_DBG(0,1,"htb_destroy q=%p\n",q);
+
+	del_timer_sync (&q->timer);
+#ifdef HTB_RATECM
+	del_timer_sync (&q->rttim);
+#endif
+	while (!list_empty(&q->root)) 
+		htb_destroy_class (sch,list_entry(q->root.next,
+					struct htb_class,sibling));
+
+	htb_destroy_filters(&q->filter_list);
+	__skb_queue_purge(&q->direct_queue);
+	MOD_DEC_USE_COUNT;
+}
+
+static int htb_delete(struct Qdisc *sch, unsigned long arg)
+{
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+	struct htb_class *cl = (struct htb_class*)arg;
+	HTB_DBG(0,1,"htb_delete q=%p cl=%X ref=%d\n",q,cl?cl->classid:0,cl?cl->refcnt:0);
+
+	// TODO: why don't allow to delete subtree ? references ? does
+	// tc subsys quarantee us that in htb_destroy it holds no class
+	// refs so that we can remove children safely there ?
+	if (!list_empty(&cl->children) || cl->filter_cnt)
+		return -EBUSY;
+	
+	sch_tree_lock(sch);
+	
+	/* delete from hash and active; remainder in destroy_class */
+	list_del_init(&cl->hlist);
+	if (cl->prio_activity)
+		htb_deactivate (q,cl);
+
+	if (--cl->refcnt == 0)
+		htb_destroy_class(sch,cl);
+
+	sch_tree_unlock(sch);
+	return 0;
+}
+
+static void htb_put(struct Qdisc *sch, unsigned long arg)
+{
+#ifdef HTB_DEBUG
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+#endif
+	struct htb_class *cl = (struct htb_class*)arg;
+	HTB_DBG(0,1,"htb_put q=%p cl=%X ref=%d\n",q,cl?cl->classid:0,cl?cl->refcnt:0);
+
+	if (--cl->refcnt == 0)
+		htb_destroy_class(sch,cl);
+}
+
+static int htb_change_class(struct Qdisc *sch, u32 classid, 
+		u32 parentid, struct rtattr **tca, unsigned long *arg)
+{
+	int err = -EINVAL;
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+	struct htb_class *cl = (struct htb_class*)*arg,*parent;
+	struct rtattr *opt = tca[TCA_OPTIONS-1];
+	struct qdisc_rate_table *rtab = NULL, *ctab = NULL;
+	struct rtattr *tb[TCA_HTB_RTAB];
+	struct tc_htb_opt *hopt;
+
+	/* extract all subattrs from opt attr */
+	if (!opt || rtattr_parse(tb, TCA_HTB_RTAB, RTA_DATA(opt), RTA_PAYLOAD(opt)) ||
+			tb[TCA_HTB_PARMS-1] == NULL ||
+			RTA_PAYLOAD(tb[TCA_HTB_PARMS-1]) < sizeof(*hopt))
+		goto failure;
+	
+	parent = parentid == TC_H_ROOT ? NULL : htb_find (parentid,sch);
+
+	hopt = RTA_DATA(tb[TCA_HTB_PARMS-1]);
+	HTB_DBG(0,1,"htb_chg cl=%p, clid=%X, opt/prio=%d, rate=%u, buff=%d, quant=%d\n", cl,cl?cl->classid:0,(int)hopt->prio,hopt->rate.rate,hopt->buffer,hopt->quantum);
+	rtab = qdisc_get_rtab(&hopt->rate, tb[TCA_HTB_RTAB-1]);
+	ctab = qdisc_get_rtab(&hopt->ceil, tb[TCA_HTB_CTAB-1]);
+	if (!rtab || !ctab) goto failure;
+
+	if (!cl) { /* new class */
+		/* check maximal depth */
+		if (parent && parent->parent && parent->parent->level < 2) {
+			printk(KERN_ERR "htb: tree is too deep\n");
+			goto failure;
+		}
+		err = -ENOBUFS;
+		if ((cl = kmalloc(sizeof(*cl), GFP_KERNEL)) == NULL)
+			goto failure;
+		
+		memset(cl, 0, sizeof(*cl));
+		cl->refcnt = 1;
+		INIT_LIST_HEAD(&cl->sibling);
+		INIT_LIST_HEAD(&cl->hlist);
+		INIT_LIST_HEAD(&cl->children);
+		INIT_LIST_HEAD(&cl->un.leaf.drop_list);
+#ifdef HTB_DEBUG
+		cl->magic = HTB_CMAGIC;
+#endif
+
+		sch_tree_lock(sch);
+		if (parent && !parent->level) {
+			/* turn parent into inner node */
+			sch->q.qlen -= parent->un.leaf.q->q.qlen;
+			qdisc_destroy (parent->un.leaf.q);
+			if (parent->prio_activity) 
+				htb_deactivate (q,parent);
+
+			/* remove from evt list because of level change */
+			if (parent->cmode != HTB_CAN_SEND) {
+				htb_safe_rb_erase(&parent->pq_node,q->wait_pq /*+0*/);
+				parent->cmode = HTB_CAN_SEND;
+			}
+			parent->level = (parent->parent ? parent->parent->level
+					: TC_HTB_MAXDEPTH) - 1;
+			memset (&parent->un.inner,0,sizeof(parent->un.inner));
+		}
+		/* leaf (we) needs elementary qdisc */
+		if (!(cl->un.leaf.q = qdisc_create_dflt(sch->dev, &pfifo_qdisc_ops)))
+			cl->un.leaf.q = &noop_qdisc;
+
+		cl->classid = classid; cl->parent = parent;
+
+		/* set class to be in HTB_CAN_SEND state */
+		cl->tokens = hopt->buffer;
+		cl->ctokens = hopt->cbuffer;
+		cl->mbuffer = 60000000; /* 1min */
+		PSCHED_GET_TIME(cl->t_c);
+		cl->cmode = HTB_CAN_SEND;
+
+		/* attach to the hash list and parent's family */
+		list_add_tail(&cl->hlist, q->hash+htb_hash(classid));
+		list_add_tail(&cl->sibling, parent ? &parent->children : &q->root);
+#ifdef HTB_DEBUG
+		{ 
+			int i;
+			for (i = 0; i < TC_HTB_NUMPRIO; i++) cl->node[i].rb_color = -1;
+			cl->pq_node.rb_color = -1;
+		}
+#endif
+	} else sch_tree_lock(sch);
+
+	cl->un.leaf.quantum = rtab->rate.rate / q->rate2quantum;
+	if (!hopt->quantum && cl->un.leaf.quantum < 1000) {
+		printk(KERN_WARNING "HTB: quantum of class %X is small. Consider r2q change.", cl->classid);
+		cl->un.leaf.quantum = 1000;
+	}
+	if (!hopt->quantum && cl->un.leaf.quantum > 200000) {
+		printk(KERN_WARNING "HTB: quantum of class %X is big. Consider r2q change.", cl->classid);
+		cl->un.leaf.quantum = 200000;
+	}
+	if (hopt->quantum)
+		cl->un.leaf.quantum = hopt->quantum;
+	if ((cl->un.leaf.prio = hopt->prio) >= TC_HTB_NUMPRIO)
+		cl->un.leaf.prio = TC_HTB_NUMPRIO - 1;
+
+	cl->buffer = hopt->buffer;
+	cl->cbuffer = hopt->cbuffer;
+	if (cl->rate) qdisc_put_rtab(cl->rate); cl->rate = rtab;
+	if (cl->ceil) qdisc_put_rtab(cl->ceil); cl->ceil = ctab;
+	sch_tree_unlock(sch);
+
+	*arg = (unsigned long)cl;
+	return 0;
+
+failure:
+	if (rtab) qdisc_put_rtab(rtab);
+	if (ctab) qdisc_put_rtab(ctab);
+	return err;
+}
+
+static struct tcf_proto **htb_find_tcf(struct Qdisc *sch, unsigned long arg)
+{
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+	struct htb_class *cl = (struct htb_class *)arg;
+	struct tcf_proto **fl = cl ? &cl->filter_list : &q->filter_list;
+	HTB_DBG(0,2,"htb_tcf q=%p clid=%X fref=%d fl=%p\n",q,cl?cl->classid:0,cl?cl->filter_cnt:q->filter_cnt,*fl);
+	return fl;
+}
+
+static unsigned long htb_bind_filter(struct Qdisc *sch, unsigned long parent,
+	u32 classid)
+{
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+	struct htb_class *cl = htb_find (classid,sch);
+	HTB_DBG(0,2,"htb_bind q=%p clid=%X cl=%p fref=%d\n",q,classid,cl,cl?cl->filter_cnt:q->filter_cnt);
+	/*if (cl && !cl->level) return 0;
+	  The line above used to be there to prevent attaching filters to 
+	  leaves. But at least tc_index filter uses this just to get class 
+	  for other reasons so that we have to allow for it.
+	  ----
+	  19.6.2002 As Werner explained it is ok - bind filter is just
+	  another way to "lock" the class - unlike "get" this lock can
+	  be broken by class during destroy IIUC.
+	 */
+	if (cl) 
+		cl->filter_cnt++; 
+	else 
+		q->filter_cnt++;
+	return (unsigned long)cl;
+}
+
+static void htb_unbind_filter(struct Qdisc *sch, unsigned long arg)
+{
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+	struct htb_class *cl = (struct htb_class *)arg;
+	HTB_DBG(0,2,"htb_unbind q=%p cl=%p fref=%d\n",q,cl,cl?cl->filter_cnt:q->filter_cnt);
+	if (cl) 
+		cl->filter_cnt--; 
+	else 
+		q->filter_cnt--;
+}
+
+static void htb_walk(struct Qdisc *sch, struct qdisc_walker *arg)
+{
+	struct htb_sched *q = (struct htb_sched *)sch->data;
+	int i;
+
+	if (arg->stop)
+		return;
+
+	for (i = 0; i < HTB_HSIZE; i++) {
+		struct list_head *p;
+		list_for_each (p,q->hash+i) {
+			struct htb_class *cl = list_entry(p,struct htb_class,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 struct Qdisc_class_ops htb_class_ops =
+{
+    htb_graft,
+    htb_leaf,
+    htb_get,
+    htb_put,
+    htb_change_class,
+    htb_delete,
+    htb_walk,
+
+    htb_find_tcf,
+    htb_bind_filter,
+    htb_unbind_filter,
+
+    htb_dump_class,
+};
+
+struct Qdisc_ops htb_qdisc_ops =
+{
+    NULL,
+    &htb_class_ops,
+    "htb",
+    sizeof(struct htb_sched),
+
+    htb_enqueue,
+    htb_dequeue,
+    htb_requeue,
+    htb_drop,
+
+    htb_init,
+    htb_reset,
+    htb_destroy,
+    NULL /* htb_change */,
+
+    htb_dump,
+};
+
+#ifdef MODULE
+int init_module(void)
+{
+    return register_qdisc(&htb_qdisc_ops);
+}
+
+void cleanup_module(void) 
+{
+    unregister_qdisc(&htb_qdisc_ops);
+}
+MODULE_LICENSE("GPL");
+#endif