Initial import

1 files changed, 1630 insertions, 0 deletions

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
new file mode 100644
index 000000000..f1acb0f60
--- /dev/null
+++ b/net/sched/sch_htb.c
@@ -0,0 +1,1630 @@
+/*
+ * 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:
+ *              Stef Coene <stef.coene@docum.org>
+ *			HTB support at LARTC mailing list
+ *		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
+ *		Tomasz Wrona, <tw@eter.tym.pl>
+ *			created test case so that I was able to fix nasty bug
+ *		Wilfried Weissmann
+ *			spotted bug in dequeue code and helped with fix
+ *		Jiri Fojtasek
+ *			fixed requeue routine
+ *		and many others. thanks.
+ */
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/skbuff.h>
+#include <linux/list.h>
+#include <linux/compiler.h>
+#include <linux/rbtree.h>
+#include <linux/workqueue.h>
+#include <linux/slab.h>
+#include <net/netlink.h>
+#include <net/sch_generic.h>
+#include <net/pkt_sched.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.
+*/
+
+static int htb_hysteresis __read_mostly = 0; /* whether to use mode hysteresis for speedup */
+#define HTB_VER 0x30011		/* 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
+
+/* Module parameter and sysfs export */
+module_param    (htb_hysteresis, int, 0640);
+MODULE_PARM_DESC(htb_hysteresis, "Hysteresis mode, less CPU load, less accurate");
+
+static int htb_rate_est = 0; /* htb classes have a default rate estimator */
+module_param(htb_rate_est, int, 0640);
+MODULE_PARM_DESC(htb_rate_est, "setup a default rate estimator (4sec 16sec) for htb classes");
+
+/* 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 */
+};
+
+struct htb_prio {
+	union {
+		struct rb_root	row;
+		struct rb_root	feed;
+	};
+	struct rb_node	*ptr;
+	/* When class changes from state 1->2 and disconnects from
+	 * parent's feed then we lost ptr value and start from the
+	 * first child again. Here we store classid of the
+	 * last valid ptr (used when ptr is NULL).
+	 */
+	u32		last_ptr_id;
+};
+
+/* interior & leaf nodes; props specific to leaves are marked L:
+ * To reduce false sharing, place mostly read fields at beginning,
+ * and mostly written ones at the end.
+ */
+struct htb_class {
+	struct Qdisc_class_common common;
+	struct psched_ratecfg	rate;
+	struct psched_ratecfg	ceil;
+	s64			buffer, cbuffer;/* token bucket depth/rate */
+	s64			mbuffer;	/* max wait time */
+	u32			prio;		/* these two are used only by leaves... */
+	int			quantum;	/* but stored for parent-to-leaf return */
+
+	struct tcf_proto __rcu	*filter_list;	/* class attached filters */
+	int			filter_cnt;
+	int			refcnt;		/* usage count of this class */
+
+	int			level;		/* our level (see above) */
+	unsigned int		children;
+	struct htb_class	*parent;	/* parent class */
+
+	struct gnet_stats_rate_est64 rate_est;
+
+	/*
+	 * Written often fields
+	 */
+	struct gnet_stats_basic_packed bstats;
+	struct gnet_stats_queue	qstats;
+	struct tc_htb_xstats	xstats;	/* our special stats */
+
+	/* token bucket parameters */
+	s64			tokens, ctokens;/* current number of tokens */
+	s64			t_c;		/* checkpoint time */
+
+	union {
+		struct htb_class_leaf {
+			struct list_head drop_list;
+			int		deficit[TC_HTB_MAXDEPTH];
+			struct Qdisc	*q;
+		} leaf;
+		struct htb_class_inner {
+			struct htb_prio clprio[TC_HTB_NUMPRIO];
+		} inner;
+	} un;
+	s64			pq_key;
+
+	int			prio_activity;	/* for which prios are we active */
+	enum htb_cmode		cmode;		/* current mode of the class */
+	struct rb_node		pq_node;	/* node for event queue */
+	struct rb_node		node[TC_HTB_NUMPRIO];	/* node for self or feed tree */
+};
+
+struct htb_level {
+	struct rb_root	wait_pq;
+	struct htb_prio hprio[TC_HTB_NUMPRIO];
+};
+
+struct htb_sched {
+	struct Qdisc_class_hash clhash;
+	int			defcls;		/* class where unclassified flows go to */
+	int			rate2quantum;	/* quant = rate / rate2quantum */
+
+	/* filters for qdisc itself */
+	struct tcf_proto __rcu	*filter_list;
+
+#define HTB_WARN_TOOMANYEVENTS	0x1
+	unsigned int		warned;	/* only one warning */
+	int			direct_qlen;
+	struct work_struct	work;
+
+	/* non shaped skbs; let them go directly thru */
+	struct sk_buff_head	direct_queue;
+	long			direct_pkts;
+
+	struct qdisc_watchdog	watchdog;
+
+	s64			now;	/* cached dequeue time */
+	struct list_head	drops[TC_HTB_NUMPRIO];/* active leaves (for drops) */
+
+	/* time of nearest event per level (row) */
+	s64			near_ev_cache[TC_HTB_MAXDEPTH];
+
+	int			row_mask[TC_HTB_MAXDEPTH];
+
+	struct htb_level	hlevel[TC_HTB_MAXDEPTH];
+};
+
+/* 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 = qdisc_priv(sch);
+	struct Qdisc_class_common *clc;
+
+	clc = qdisc_class_find(&q->clhash, handle);
+	if (clc == NULL)
+		return NULL;
+	return container_of(clc, struct htb_class, common);
+}
+
+/**
+ * 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 unsuccessful
+ * then finish and return direct queue.
+ */
+#define HTB_DIRECT ((struct htb_class *)-1L)
+
+static struct htb_class *htb_classify(struct sk_buff *skb, struct Qdisc *sch,
+				      int *qerr)
+{
+	struct htb_sched *q = qdisc_priv(sch);
+	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 */
+	cl = htb_find(skb->priority, sch);
+	if (cl) {
+		if (cl->level == 0)
+			return cl;
+		/* Start with inner filter chain if a non-leaf class is selected */
+		tcf = rcu_dereference_bh(cl->filter_list);
+	} else {
+		tcf = rcu_dereference_bh(q->filter_list);
+	}
+
+	*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
+	while (tcf && (result = tc_classify(skb, tcf, &res)) >= 0) {
+#ifdef CONFIG_NET_CLS_ACT
+		switch (result) {
+		case TC_ACT_QUEUED:
+		case TC_ACT_STOLEN:
+			*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
+		case TC_ACT_SHOT:
+			return NULL;
+		}
+#endif
+		cl = (void *)res.class;
+		if (!cl) {
+			if (res.classid == sch->handle)
+				return HTB_DIRECT;	/* X:0 (direct flow) */
+			cl = htb_find(res.classid, sch);
+			if (!cl)
+				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 = rcu_dereference_bh(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;
+}
+
+/**
+ * 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(struct rb_root *root,
+			       struct htb_class *cl, int prio)
+{
+	struct rb_node **p = &root->rb_node, *parent = NULL;
+
+	while (*p) {
+		struct htb_class *c;
+		parent = *p;
+		c = rb_entry(parent, struct htb_class, node[prio]);
+
+		if (cl->common.classid > c->common.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, s64 delay)
+{
+	struct rb_node **p = &q->hlevel[cl->level].wait_pq.rb_node, *parent = NULL;
+
+	cl->pq_key = q->now + delay;
+	if (cl->pq_key == q->now)
+		cl->pq_key++;
+
+	/* update the nearest event cache */
+	if (q->near_ev_cache[cl->level] > cl->pq_key)
+		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)
+			p = &parent->rb_right;
+		else
+			p = &parent->rb_left;
+	}
+	rb_link_node(&cl->pq_node, parent, p);
+	rb_insert_color(&cl->pq_node, &q->hlevel[cl->level].wait_pq);
+}
+
+/**
+ * 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 inline void htb_next_rb_node(struct rb_node **n)
+{
+	*n = rb_next(*n);
+}
+
+/**
+ * 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)
+{
+	q->row_mask[cl->level] |= mask;
+	while (mask) {
+		int prio = ffz(~mask);
+		mask &= ~(1 << prio);
+		htb_add_to_id_tree(&q->hlevel[cl->level].hprio[prio].row, cl, prio);
+	}
+}
+
+/* If this triggers, it is a bug in this code, but it need not be fatal */
+static void htb_safe_rb_erase(struct rb_node *rb, struct rb_root *root)
+{
+	if (RB_EMPTY_NODE(rb)) {
+		WARN_ON(1);
+	} else {
+		rb_erase(rb, root);
+		RB_CLEAR_NODE(rb);
+	}
+}
+
+
+/**
+ * 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;
+	struct htb_level *hlevel = &q->hlevel[cl->level];
+
+	while (mask) {
+		int prio = ffz(~mask);
+		struct htb_prio *hprio = &hlevel->hprio[prio];
+
+		mask &= ~(1 << prio);
+		if (hprio->ptr == cl->node + prio)
+			htb_next_rb_node(&hprio->ptr);
+
+		htb_safe_rb_erase(cl->node + prio, &hprio->row);
+		if (!hprio->row.rb_node)
+			m |= 1 << prio;
+	}
+	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;
+
+	while (cl->cmode == HTB_MAY_BORROW && p && mask) {
+		m = mask;
+		while (m) {
+			int prio = ffz(~m);
+			m &= ~(1 << prio);
+
+			if (p->un.inner.clprio[prio].feed.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(&p->un.inner.clprio[prio].feed, cl, prio);
+		}
+		p->prio_activity |= mask;
+		cl = p;
+		p = cl->parent;
+
+	}
+	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;
+
+	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.clprio[prio].ptr == cl->node + prio) {
+				/* we are removing child which is pointed to from
+				 * parent feed - forget the pointer but remember
+				 * classid
+				 */
+				p->un.inner.clprio[prio].last_ptr_id = cl->common.classid;
+				p->un.inner.clprio[prio].ptr = NULL;
+			}
+
+			htb_safe_rb_erase(cl->node + prio,
+					  &p->un.inner.clprio[prio].feed);
+
+			if (!p->un.inner.clprio[prio].feed.rb_node)
+				mask |= 1 << prio;
+		}
+
+		p->prio_activity &= ~mask;
+		cl = p;
+		p = cl->parent;
+
+	}
+	if (cl->cmode == HTB_CAN_SEND && mask)
+		htb_remove_class_from_row(q, cl, mask);
+}
+
+static inline s64 htb_lowater(const struct htb_class *cl)
+{
+	if (htb_hysteresis)
+		return cl->cmode != HTB_CANT_SEND ? -cl->cbuffer : 0;
+	else
+		return 0;
+}
+static inline s64 htb_hiwater(const struct htb_class *cl)
+{
+	if (htb_hysteresis)
+		return cl->cmode == HTB_CAN_SEND ? -cl->buffer : 0;
+	else
+		return 0;
+}
+
+
+/**
+ * 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, s64 *diff)
+{
+	s64 toks;
+
+	if ((toks = (cl->ctokens + *diff)) < htb_lowater(cl)) {
+		*diff = -toks;
+		return HTB_CANT_SEND;
+	}
+
+	if ((toks = (cl->tokens + *diff)) >= htb_hiwater(cl))
+		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, s64 *diff)
+{
+	enum htb_cmode new_mode = htb_class_mode(cl, diff);
+
+	if (new_mode == cl->cmode)
+		return;
+
+	if (cl->prio_activity) {	/* not necessary: 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)
+{
+	WARN_ON(cl->level || !cl->un.leaf.q || !cl->un.leaf.q->q.qlen);
+
+	if (!cl->prio_activity) {
+		cl->prio_activity = 1 << cl->prio;
+		htb_activate_prios(q, cl);
+		list_add_tail(&cl->un.leaf.drop_list,
+			      q->drops + cl->prio);
+	}
+}
+
+/**
+ * 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)
+{
+	WARN_ON(!cl->prio_activity);
+
+	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)
+{
+	int uninitialized_var(ret);
+	struct htb_sched *q = qdisc_priv(sch);
+	struct htb_class *cl = htb_classify(skb, sch, &ret);
+
+	if (cl == HTB_DIRECT) {
+		/* enqueue to helper queue */
+		if (q->direct_queue.qlen < q->direct_qlen) {
+			__skb_queue_tail(&q->direct_queue, skb);
+			q->direct_pkts++;
+		} else {
+			return qdisc_drop(skb, sch);
+		}
+#ifdef CONFIG_NET_CLS_ACT
+	} else if (!cl) {
+		if (ret & __NET_XMIT_BYPASS)
+			qdisc_qstats_drop(sch);
+		kfree_skb(skb);
+		return ret;
+#endif
+	} else if ((ret = qdisc_enqueue(skb, cl->un.leaf.q)) != NET_XMIT_SUCCESS) {
+		if (net_xmit_drop_count(ret)) {
+			qdisc_qstats_drop(sch);
+			cl->qstats.drops++;
+		}
+		return ret;
+	} else {
+		htb_activate(q, cl);
+	}
+
+	sch->q.qlen++;
+	return NET_XMIT_SUCCESS;
+}
+
+static inline void htb_accnt_tokens(struct htb_class *cl, int bytes, s64 diff)
+{
+	s64 toks = diff + cl->tokens;
+
+	if (toks > cl->buffer)
+		toks = cl->buffer;
+	toks -= (s64) psched_l2t_ns(&cl->rate, bytes);
+	if (toks <= -cl->mbuffer)
+		toks = 1 - cl->mbuffer;
+
+	cl->tokens = toks;
+}
+
+static inline void htb_accnt_ctokens(struct htb_class *cl, int bytes, s64 diff)
+{
+	s64 toks = diff + cl->ctokens;
+
+	if (toks > cl->cbuffer)
+		toks = cl->cbuffer;
+	toks -= (s64) psched_l2t_ns(&cl->ceil, bytes);
+	if (toks <= -cl->mbuffer)
+		toks = 1 - cl->mbuffer;
+
+	cl->ctokens = toks;
+}
+
+/**
+ * htb_charge_class - charges amount "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, struct sk_buff *skb)
+{
+	int bytes = qdisc_pkt_len(skb);
+	enum htb_cmode old_mode;
+	s64 diff;
+
+	while (cl) {
+		diff = min_t(s64, q->now - cl->t_c, cl->mbuffer);
+		if (cl->level >= level) {
+			if (cl->level == level)
+				cl->xstats.lends++;
+			htb_accnt_tokens(cl, bytes, diff);
+		} else {
+			cl->xstats.borrows++;
+			cl->tokens += diff;	/* we moved t_c; update tokens */
+		}
+		htb_accnt_ctokens(cl, bytes, diff);
+		cl->t_c = q->now;
+
+		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->hlevel[cl->level].wait_pq);
+			if (cl->cmode != HTB_CAN_SEND)
+				htb_add_to_wait_tree(q, cl, diff);
+		}
+
+		/* update basic stats except for leaves which are already updated */
+		if (cl->level)
+			bstats_update(&cl->bstats, skb);
+
+		cl = cl->parent;
+	}
+}
+
+/**
+ * htb_do_events - make mode changes to classes at the level
+ *
+ * Scans event queue for pending events and applies them. Returns time of
+ * next pending event (0 for no event in pq, q->now for too many events).
+ * Note: Applied are events whose have cl->pq_key <= q->now.
+ */
+static s64 htb_do_events(struct htb_sched *q, const int level,
+			 unsigned long start)
+{
+	/* don't run for longer than 2 jiffies; 2 is used instead of
+	 * 1 to simplify things when jiffy is going to be incremented
+	 * too soon
+	 */
+	unsigned long stop_at = start + 2;
+	struct rb_root *wait_pq = &q->hlevel[level].wait_pq;
+
+	while (time_before(jiffies, stop_at)) {
+		struct htb_class *cl;
+		s64 diff;
+		struct rb_node *p = rb_first(wait_pq);
+
+		if (!p)
+			return 0;
+
+		cl = rb_entry(p, struct htb_class, pq_node);
+		if (cl->pq_key > q->now)
+			return cl->pq_key;
+
+		htb_safe_rb_erase(p, wait_pq);
+		diff = min_t(s64, q->now - cl->t_c, cl->mbuffer);
+		htb_change_class_mode(q, cl, &diff);
+		if (cl->cmode != HTB_CAN_SEND)
+			htb_add_to_wait_tree(q, cl, diff);
+	}
+
+	/* too much load - let's continue after a break for scheduling */
+	if (!(q->warned & HTB_WARN_TOOMANYEVENTS)) {
+		pr_warn("htb: too many events!\n");
+		q->warned |= HTB_WARN_TOOMANYEVENTS;
+	}
+
+	return q->now;
+}
+
+/* Returns class->node+prio from id-tree where classe's id is >= id. NULL
+ * is no such one exists.
+ */
+static struct rb_node *htb_id_find_next_upper(int prio, struct rb_node *n,
+					      u32 id)
+{
+	struct rb_node *r = NULL;
+	while (n) {
+		struct htb_class *cl =
+		    rb_entry(n, struct htb_class, node[prio]);
+
+		if (id > cl->common.classid) {
+			n = n->rb_right;
+		} else if (id < cl->common.classid) {
+			r = n;
+			n = n->rb_left;
+		} else {
+			return n;
+		}
+	}
+	return r;
+}
+
+/**
+ * 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(struct htb_prio *hprio, const int prio)
+{
+	int i;
+	struct {
+		struct rb_node *root;
+		struct rb_node **pptr;
+		u32 *pid;
+	} stk[TC_HTB_MAXDEPTH], *sp = stk;
+
+	BUG_ON(!hprio->row.rb_node);
+	sp->root = hprio->row.rb_node;
+	sp->pptr = &hprio->ptr;
+	sp->pid = &hprio->last_ptr_id;
+
+	for (i = 0; i < 65535; i++) {
+		if (!*sp->pptr && *sp->pid) {
+			/* ptr was invalidated but id is valid - try to recover
+			 * the original or next ptr
+			 */
+			*sp->pptr =
+			    htb_id_find_next_upper(prio, sp->root, *sp->pid);
+		}
+		*sp->pid = 0;	/* ptr is valid now so that remove this hint as it
+				 * can become out of date quickly
+				 */
+		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--;
+				if (!*sp->pptr) {
+					WARN_ON(1);
+					return NULL;
+				}
+				htb_next_rb_node(sp->pptr);
+			}
+		} else {
+			struct htb_class *cl;
+			struct htb_prio *clp;
+
+			cl = rb_entry(*sp->pptr, struct htb_class, node[prio]);
+			if (!cl->level)
+				return cl;
+			clp = &cl->un.inner.clprio[prio];
+			(++sp)->root = clp->feed.rb_node;
+			sp->pptr = &clp->ptr;
+			sp->pid = &clp->last_ptr_id;
+		}
+	}
+	WARN_ON(1);
+	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, const int prio,
+					const int level)
+{
+	struct sk_buff *skb = NULL;
+	struct htb_class *cl, *start;
+	struct htb_level *hlevel = &q->hlevel[level];
+	struct htb_prio *hprio = &hlevel->hprio[prio];
+
+	/* look initial class up in the row */
+	start = cl = htb_lookup_leaf(hprio, prio);
+
+	do {
+next:
+		if (unlikely(!cl))
+			return NULL;
+
+		/* class can be empty - it is unlikely but can be true if leaf
+		 * qdisc drops packets in enqueue routine or if someone used
+		 * graft operation on the leaf since last dequeue;
+		 * simply deactivate and skip such class
+		 */
+		if (unlikely(cl->un.leaf.q->q.qlen == 0)) {
+			struct htb_class *next;
+			htb_deactivate(q, cl);
+
+			/* row/level might become empty */
+			if ((q->row_mask[level] & (1 << prio)) == 0)
+				return NULL;
+
+			next = htb_lookup_leaf(hprio, prio);
+
+			if (cl == start)	/* fix start if we just deleted it */
+				start = next;
+			cl = next;
+			goto next;
+		}
+
+		skb = cl->un.leaf.q->dequeue(cl->un.leaf.q);
+		if (likely(skb != NULL))
+			break;
+
+		qdisc_warn_nonwc("htb", cl->un.leaf.q);
+		htb_next_rb_node(level ? &cl->parent->un.inner.clprio[prio].ptr:
+					 &q->hlevel[0].hprio[prio].ptr);
+		cl = htb_lookup_leaf(hprio, prio);
+
+	} while (cl != start);
+
+	if (likely(skb != NULL)) {
+		bstats_update(&cl->bstats, skb);
+		cl->un.leaf.deficit[level] -= qdisc_pkt_len(skb);
+		if (cl->un.leaf.deficit[level] < 0) {
+			cl->un.leaf.deficit[level] += cl->quantum;
+			htb_next_rb_node(level ? &cl->parent->un.inner.clprio[prio].ptr :
+						 &q->hlevel[0].hprio[prio].ptr);
+		}
+		/* 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);
+		htb_charge_class(q, cl, level, skb);
+	}
+	return skb;
+}
+
+static struct sk_buff *htb_dequeue(struct Qdisc *sch)
+{
+	struct sk_buff *skb;
+	struct htb_sched *q = qdisc_priv(sch);
+	int level;
+	s64 next_event;
+	unsigned long start_at;
+
+	/* try to dequeue direct packets as high prio (!) to minimize cpu work */
+	skb = __skb_dequeue(&q->direct_queue);
+	if (skb != NULL) {
+ok:
+		qdisc_bstats_update(sch, skb);
+		qdisc_unthrottled(sch);
+		sch->q.qlen--;
+		return skb;
+	}
+
+	if (!sch->q.qlen)
+		goto fin;
+	q->now = ktime_get_ns();
+	start_at = jiffies;
+
+	next_event = q->now + 5LLU * NSEC_PER_SEC;
+
+	for (level = 0; level < TC_HTB_MAXDEPTH; level++) {
+		/* common case optimization - skip event handler quickly */
+		int m;
+		s64 event = q->near_ev_cache[level];
+
+		if (q->now >= event) {
+			event = htb_do_events(q, level, start_at);
+			if (!event)
+				event = q->now + NSEC_PER_SEC;
+			q->near_ev_cache[level] = event;
+		}
+
+		if (next_event > event)
+			next_event = event;
+
+		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))
+				goto ok;
+		}
+	}
+	qdisc_qstats_overlimit(sch);
+	if (likely(next_event > q->now)) {
+		if (!test_bit(__QDISC_STATE_DEACTIVATED,
+			      &qdisc_root_sleeping(q->watchdog.qdisc)->state)) {
+			ktime_t time = ns_to_ktime(next_event);
+			qdisc_throttled(q->watchdog.qdisc);
+			hrtimer_start(&q->watchdog.timer, time,
+				      HRTIMER_MODE_ABS_PINNED);
+		}
+	} else {
+		schedule_work(&q->work);
+	}
+fin:
+	return skb;
+}
+
+/* try to drop from each class (by prio) until one succeed */
+static unsigned int htb_drop(struct Qdisc *sch)
+{
+	struct htb_sched *q = qdisc_priv(sch);
+	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);
+			unsigned int len;
+			if (cl->un.leaf.q->ops->drop &&
+			    (len = 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 len;
+			}
+		}
+	}
+	return 0;
+}
+
+/* reset all classes */
+/* always caled under BH & queue lock */
+static void htb_reset(struct Qdisc *sch)
+{
+	struct htb_sched *q = qdisc_priv(sch);
+	struct htb_class *cl;
+	unsigned int i;
+
+	for (i = 0; i < q->clhash.hashsize; i++) {
+		hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
+			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;
+
+		}
+	}
+	qdisc_watchdog_cancel(&q->watchdog);
+	__skb_queue_purge(&q->direct_queue);
+	sch->q.qlen = 0;
+	memset(q->hlevel, 0, sizeof(q->hlevel));
+	memset(q->row_mask, 0, sizeof(q->row_mask));
+	for (i = 0; i < TC_HTB_NUMPRIO; i++)
+		INIT_LIST_HEAD(q->drops + i);
+}
+
+static const struct nla_policy htb_policy[TCA_HTB_MAX + 1] = {
+	[TCA_HTB_PARMS]	= { .len = sizeof(struct tc_htb_opt) },
+	[TCA_HTB_INIT]	= { .len = sizeof(struct tc_htb_glob) },
+	[TCA_HTB_CTAB]	= { .type = NLA_BINARY, .len = TC_RTAB_SIZE },
+	[TCA_HTB_RTAB]	= { .type = NLA_BINARY, .len = TC_RTAB_SIZE },
+	[TCA_HTB_DIRECT_QLEN] = { .type = NLA_U32 },
+	[TCA_HTB_RATE64] = { .type = NLA_U64 },
+	[TCA_HTB_CEIL64] = { .type = NLA_U64 },
+};
+
+static void htb_work_func(struct work_struct *work)
+{
+	struct htb_sched *q = container_of(work, struct htb_sched, work);
+	struct Qdisc *sch = q->watchdog.qdisc;
+
+	__netif_schedule(qdisc_root(sch));
+}
+
+static int htb_init(struct Qdisc *sch, struct nlattr *opt)
+{
+	struct htb_sched *q = qdisc_priv(sch);
+	struct nlattr *tb[TCA_HTB_MAX + 1];
+	struct tc_htb_glob *gopt;
+	int err;
+	int i;
+
+	if (!opt)
+		return -EINVAL;
+
+	err = nla_parse_nested(tb, TCA_HTB_MAX, opt, htb_policy);
+	if (err < 0)
+		return err;
+
+	if (!tb[TCA_HTB_INIT])
+		return -EINVAL;
+
+	gopt = nla_data(tb[TCA_HTB_INIT]);
+	if (gopt->version != HTB_VER >> 16)
+		return -EINVAL;
+
+	err = qdisc_class_hash_init(&q->clhash);
+	if (err < 0)
+		return err;
+	for (i = 0; i < TC_HTB_NUMPRIO; i++)
+		INIT_LIST_HEAD(q->drops + i);
+
+	qdisc_watchdog_init(&q->watchdog, sch);
+	INIT_WORK(&q->work, htb_work_func);
+	__skb_queue_head_init(&q->direct_queue);
+
+	if (tb[TCA_HTB_DIRECT_QLEN])
+		q->direct_qlen = nla_get_u32(tb[TCA_HTB_DIRECT_QLEN]);
+	else {
+		q->direct_qlen = qdisc_dev(sch)->tx_queue_len;
+		if (q->direct_qlen < 2)	/* some devices have zero tx_queue_len */
+			q->direct_qlen = 2;
+	}
+	if ((q->rate2quantum = gopt->rate2quantum) < 1)
+		q->rate2quantum = 1;
+	q->defcls = gopt->defcls;
+
+	return 0;
+}
+
+static int htb_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+	struct htb_sched *q = qdisc_priv(sch);
+	struct nlattr *nest;
+	struct tc_htb_glob gopt;
+
+	/* Its safe to not acquire qdisc lock. As we hold RTNL,
+	 * no change can happen on the qdisc parameters.
+	 */
+
+	gopt.direct_pkts = q->direct_pkts;
+	gopt.version = HTB_VER;
+	gopt.rate2quantum = q->rate2quantum;
+	gopt.defcls = q->defcls;
+	gopt.debug = 0;
+
+	nest = nla_nest_start(skb, TCA_OPTIONS);
+	if (nest == NULL)
+		goto nla_put_failure;
+	if (nla_put(skb, TCA_HTB_INIT, sizeof(gopt), &gopt) ||
+	    nla_put_u32(skb, TCA_HTB_DIRECT_QLEN, q->direct_qlen))
+		goto nla_put_failure;
+
+	return nla_nest_end(skb, nest);
+
+nla_put_failure:
+	nla_nest_cancel(skb, nest);
+	return -1;
+}
+
+static int htb_dump_class(struct Qdisc *sch, unsigned long arg,
+			  struct sk_buff *skb, struct tcmsg *tcm)
+{
+	struct htb_class *cl = (struct htb_class *)arg;
+	struct nlattr *nest;
+	struct tc_htb_opt opt;
+
+	/* Its safe to not acquire qdisc lock. As we hold RTNL,
+	 * no change can happen on the class parameters.
+	 */
+	tcm->tcm_parent = cl->parent ? cl->parent->common.classid : TC_H_ROOT;
+	tcm->tcm_handle = cl->common.classid;
+	if (!cl->level && cl->un.leaf.q)
+		tcm->tcm_info = cl->un.leaf.q->handle;
+
+	nest = nla_nest_start(skb, TCA_OPTIONS);
+	if (nest == NULL)
+		goto nla_put_failure;
+
+	memset(&opt, 0, sizeof(opt));
+
+	psched_ratecfg_getrate(&opt.rate, &cl->rate);
+	opt.buffer = PSCHED_NS2TICKS(cl->buffer);
+	psched_ratecfg_getrate(&opt.ceil, &cl->ceil);
+	opt.cbuffer = PSCHED_NS2TICKS(cl->cbuffer);
+	opt.quantum = cl->quantum;
+	opt.prio = cl->prio;
+	opt.level = cl->level;
+	if (nla_put(skb, TCA_HTB_PARMS, sizeof(opt), &opt))
+		goto nla_put_failure;
+	if ((cl->rate.rate_bytes_ps >= (1ULL << 32)) &&
+	    nla_put_u64(skb, TCA_HTB_RATE64, cl->rate.rate_bytes_ps))
+		goto nla_put_failure;
+	if ((cl->ceil.rate_bytes_ps >= (1ULL << 32)) &&
+	    nla_put_u64(skb, TCA_HTB_CEIL64, cl->ceil.rate_bytes_ps))
+		goto nla_put_failure;
+
+	return nla_nest_end(skb, nest);
+
+nla_put_failure:
+	nla_nest_cancel(skb, nest);
+	return -1;
+}
+
+static int
+htb_dump_class_stats(struct Qdisc *sch, unsigned long arg, struct gnet_dump *d)
+{
+	struct htb_class *cl = (struct htb_class *)arg;
+	__u32 qlen = 0;
+
+	if (!cl->level && cl->un.leaf.q)
+		qlen = cl->un.leaf.q->q.qlen;
+	cl->xstats.tokens = PSCHED_NS2TICKS(cl->tokens);
+	cl->xstats.ctokens = PSCHED_NS2TICKS(cl->ctokens);
+
+	if (gnet_stats_copy_basic(d, NULL, &cl->bstats) < 0 ||
+	    gnet_stats_copy_rate_est(d, NULL, &cl->rate_est) < 0 ||
+	    gnet_stats_copy_queue(d, NULL, &cl->qstats, qlen) < 0)
+		return -1;
+
+	return gnet_stats_copy_app(d, &cl->xstats, sizeof(cl->xstats));
+}
+
+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->level)
+		return -EINVAL;
+	if (new == NULL &&
+	    (new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
+				     cl->common.classid)) == NULL)
+		return -ENOBUFS;
+
+	sch_tree_lock(sch);
+	*old = cl->un.leaf.q;
+	cl->un.leaf.q = new;
+	if (*old != NULL) {
+		qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
+		qdisc_reset(*old);
+	}
+	sch_tree_unlock(sch);
+	return 0;
+}
+
+static struct Qdisc *htb_leaf(struct Qdisc *sch, unsigned long arg)
+{
+	struct htb_class *cl = (struct htb_class *)arg;
+	return !cl->level ? cl->un.leaf.q : NULL;
+}
+
+static void htb_qlen_notify(struct Qdisc *sch, unsigned long arg)
+{
+	struct htb_class *cl = (struct htb_class *)arg;
+
+	if (cl->un.leaf.q->q.qlen == 0)
+		htb_deactivate(qdisc_priv(sch), cl);
+}
+
+static unsigned long htb_get(struct Qdisc *sch, u32 classid)
+{
+	struct htb_class *cl = htb_find(classid, sch);
+	if (cl)
+		cl->refcnt++;
+	return (unsigned long)cl;
+}
+
+static inline int htb_parent_last_child(struct htb_class *cl)
+{
+	if (!cl->parent)
+		/* the root class */
+		return 0;
+	if (cl->parent->children > 1)
+		/* not the last child */
+		return 0;
+	return 1;
+}
+
+static void htb_parent_to_leaf(struct htb_sched *q, struct htb_class *cl,
+			       struct Qdisc *new_q)
+{
+	struct htb_class *parent = cl->parent;
+
+	WARN_ON(cl->level || !cl->un.leaf.q || cl->prio_activity);
+
+	if (parent->cmode != HTB_CAN_SEND)
+		htb_safe_rb_erase(&parent->pq_node,
+				  &q->hlevel[parent->level].wait_pq);
+
+	parent->level = 0;
+	memset(&parent->un.inner, 0, sizeof(parent->un.inner));
+	INIT_LIST_HEAD(&parent->un.leaf.drop_list);
+	parent->un.leaf.q = new_q ? new_q : &noop_qdisc;
+	parent->tokens = parent->buffer;
+	parent->ctokens = parent->cbuffer;
+	parent->t_c = ktime_get_ns();
+	parent->cmode = HTB_CAN_SEND;
+}
+
+static void htb_destroy_class(struct Qdisc *sch, struct htb_class *cl)
+{
+	if (!cl->level) {
+		WARN_ON(!cl->un.leaf.q);
+		qdisc_destroy(cl->un.leaf.q);
+	}
+	gen_kill_estimator(&cl->bstats, &cl->rate_est);
+	tcf_destroy_chain(&cl->filter_list);
+	kfree(cl);
+}
+
+static void htb_destroy(struct Qdisc *sch)
+{
+	struct htb_sched *q = qdisc_priv(sch);
+	struct hlist_node *next;
+	struct htb_class *cl;
+	unsigned int i;
+
+	cancel_work_sync(&q->work);
+	qdisc_watchdog_cancel(&q->watchdog);
+	/* This line used to be after htb_destroy_class call below
+	 * and surprisingly it worked in 2.4. But it must precede it
+	 * because filter need its target class alive to be able to call
+	 * unbind_filter on it (without Oops).
+	 */
+	tcf_destroy_chain(&q->filter_list);
+
+	for (i = 0; i < q->clhash.hashsize; i++) {
+		hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode)
+			tcf_destroy_chain(&cl->filter_list);
+	}
+	for (i = 0; i < q->clhash.hashsize; i++) {
+		hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],
+					  common.hnode)
+			htb_destroy_class(sch, cl);
+	}
+	qdisc_class_hash_destroy(&q->clhash);
+	__skb_queue_purge(&q->direct_queue);
+}
+
+static int htb_delete(struct Qdisc *sch, unsigned long arg)
+{
+	struct htb_sched *q = qdisc_priv(sch);
+	struct htb_class *cl = (struct htb_class *)arg;
+	unsigned int qlen;
+	struct Qdisc *new_q = NULL;
+	int last_child = 0;
+
+	/* TODO: why don't allow to delete subtree ? references ? does
+	 * tc subsys guarantee us that in htb_destroy it holds no class
+	 * refs so that we can remove children safely there ?
+	 */
+	if (cl->children || cl->filter_cnt)
+		return -EBUSY;
+
+	if (!cl->level && htb_parent_last_child(cl)) {
+		new_q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
+					  cl->parent->common.classid);
+		last_child = 1;
+	}
+
+	sch_tree_lock(sch);
+
+	if (!cl->level) {
+		qlen = cl->un.leaf.q->q.qlen;
+		qdisc_reset(cl->un.leaf.q);
+		qdisc_tree_decrease_qlen(cl->un.leaf.q, qlen);
+	}
+
+	/* delete from hash and active; remainder in destroy_class */
+	qdisc_class_hash_remove(&q->clhash, &cl->common);
+	if (cl->parent)
+		cl->parent->children--;
+
+	if (cl->prio_activity)
+		htb_deactivate(q, cl);
+
+	if (cl->cmode != HTB_CAN_SEND)
+		htb_safe_rb_erase(&cl->pq_node,
+				  &q->hlevel[cl->level].wait_pq);
+
+	if (last_child)
+		htb_parent_to_leaf(q, cl, new_q);
+
+	BUG_ON(--cl->refcnt == 0);
+	/*
+	 * This shouldn't happen: we "hold" one cops->get() when called
+	 * from tc_ctl_tclass; the destroy method is done from cops->put().
+	 */
+
+	sch_tree_unlock(sch);
+	return 0;
+}
+
+static void htb_put(struct Qdisc *sch, unsigned long arg)
+{
+	struct htb_class *cl = (struct htb_class *)arg;
+
+	if (--cl->refcnt == 0)
+		htb_destroy_class(sch, cl);
+}
+
+static int htb_change_class(struct Qdisc *sch, u32 classid,
+			    u32 parentid, struct nlattr **tca,
+			    unsigned long *arg)
+{
+	int err = -EINVAL;
+	struct htb_sched *q = qdisc_priv(sch);
+	struct htb_class *cl = (struct htb_class *)*arg, *parent;
+	struct nlattr *opt = tca[TCA_OPTIONS];
+	struct nlattr *tb[TCA_HTB_MAX + 1];
+	struct tc_htb_opt *hopt;
+	u64 rate64, ceil64;
+
+	/* extract all subattrs from opt attr */
+	if (!opt)
+		goto failure;
+
+	err = nla_parse_nested(tb, TCA_HTB_MAX, opt, htb_policy);
+	if (err < 0)
+		goto failure;
+
+	err = -EINVAL;
+	if (tb[TCA_HTB_PARMS] == NULL)
+		goto failure;
+
+	parent = parentid == TC_H_ROOT ? NULL : htb_find(parentid, sch);
+
+	hopt = nla_data(tb[TCA_HTB_PARMS]);
+	if (!hopt->rate.rate || !hopt->ceil.rate)
+		goto failure;
+
+	/* Keeping backward compatible with rate_table based iproute2 tc */
+	if (hopt->rate.linklayer == TC_LINKLAYER_UNAWARE)
+		qdisc_put_rtab(qdisc_get_rtab(&hopt->rate, tb[TCA_HTB_RTAB]));
+
+	if (hopt->ceil.linklayer == TC_LINKLAYER_UNAWARE)
+		qdisc_put_rtab(qdisc_get_rtab(&hopt->ceil, tb[TCA_HTB_CTAB]));
+
+	if (!cl) {		/* new class */
+		struct Qdisc *new_q;
+		int prio;
+		struct {
+			struct nlattr		nla;
+			struct gnet_estimator	opt;
+		} est = {
+			.nla = {
+				.nla_len	= nla_attr_size(sizeof(est.opt)),
+				.nla_type	= TCA_RATE,
+			},
+			.opt = {
+				/* 4s interval, 16s averaging constant */
+				.interval	= 2,
+				.ewma_log	= 2,
+			},
+		};
+
+		/* check for valid classid */
+		if (!classid || TC_H_MAJ(classid ^ sch->handle) ||
+		    htb_find(classid, sch))
+			goto failure;
+
+		/* check maximal depth */
+		if (parent && parent->parent && parent->parent->level < 2) {
+			pr_err("htb: tree is too deep\n");
+			goto failure;
+		}
+		err = -ENOBUFS;
+		cl = kzalloc(sizeof(*cl), GFP_KERNEL);
+		if (!cl)
+			goto failure;
+
+		if (htb_rate_est || tca[TCA_RATE]) {
+			err = gen_new_estimator(&cl->bstats, NULL,
+						&cl->rate_est,
+						qdisc_root_sleeping_lock(sch),
+						tca[TCA_RATE] ? : &est.nla);
+			if (err) {
+				kfree(cl);
+				goto failure;
+			}
+		}
+
+		cl->refcnt = 1;
+		cl->children = 0;
+		INIT_LIST_HEAD(&cl->un.leaf.drop_list);
+		RB_CLEAR_NODE(&cl->pq_node);
+
+		for (prio = 0; prio < TC_HTB_NUMPRIO; prio++)
+			RB_CLEAR_NODE(&cl->node[prio]);
+
+		/* create leaf qdisc early because it uses kmalloc(GFP_KERNEL)
+		 * so that can't be used inside of sch_tree_lock
+		 * -- thanks to Karlis Peisenieks
+		 */
+		new_q = qdisc_create_dflt(sch->dev_queue,
+					  &pfifo_qdisc_ops, classid);
+		sch_tree_lock(sch);
+		if (parent && !parent->level) {
+			unsigned int qlen = parent->un.leaf.q->q.qlen;
+
+			/* turn parent into inner node */
+			qdisc_reset(parent->un.leaf.q);
+			qdisc_tree_decrease_qlen(parent->un.leaf.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->hlevel[0].wait_pq);
+				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 */
+		cl->un.leaf.q = new_q ? new_q : &noop_qdisc;
+
+		cl->common.classid = classid;
+		cl->parent = parent;
+
+		/* set class to be in HTB_CAN_SEND state */
+		cl->tokens = PSCHED_TICKS2NS(hopt->buffer);
+		cl->ctokens = PSCHED_TICKS2NS(hopt->cbuffer);
+		cl->mbuffer = 60ULL * NSEC_PER_SEC;	/* 1min */
+		cl->t_c = ktime_get_ns();
+		cl->cmode = HTB_CAN_SEND;
+
+		/* attach to the hash list and parent's family */
+		qdisc_class_hash_insert(&q->clhash, &cl->common);
+		if (parent)
+			parent->children++;
+	} else {
+		if (tca[TCA_RATE]) {
+			spinlock_t *lock = qdisc_root_sleeping_lock(sch);
+
+			err = gen_replace_estimator(&cl->bstats, NULL,
+						    &cl->rate_est,
+						    lock,
+						    tca[TCA_RATE]);
+			if (err)
+				return err;
+		}
+		sch_tree_lock(sch);
+	}
+
+	rate64 = tb[TCA_HTB_RATE64] ? nla_get_u64(tb[TCA_HTB_RATE64]) : 0;
+
+	ceil64 = tb[TCA_HTB_CEIL64] ? nla_get_u64(tb[TCA_HTB_CEIL64]) : 0;
+
+	psched_ratecfg_precompute(&cl->rate, &hopt->rate, rate64);
+	psched_ratecfg_precompute(&cl->ceil, &hopt->ceil, ceil64);
+
+	/* it used to be a nasty bug here, we have to check that node
+	 * is really leaf before changing cl->un.leaf !
+	 */
+	if (!cl->level) {
+		u64 quantum = cl->rate.rate_bytes_ps;
+
+		do_div(quantum, q->rate2quantum);
+		cl->quantum = min_t(u64, quantum, INT_MAX);
+
+		if (!hopt->quantum && cl->quantum < 1000) {
+			pr_warn("HTB: quantum of class %X is small. Consider r2q change.\n",
+				cl->common.classid);
+			cl->quantum = 1000;
+		}
+		if (!hopt->quantum && cl->quantum > 200000) {
+			pr_warn("HTB: quantum of class %X is big. Consider r2q change.\n",
+				cl->common.classid);
+			cl->quantum = 200000;
+		}
+		if (hopt->quantum)
+			cl->quantum = hopt->quantum;
+		if ((cl->prio = hopt->prio) >= TC_HTB_NUMPRIO)
+			cl->prio = TC_HTB_NUMPRIO - 1;
+	}
+
+	cl->buffer = PSCHED_TICKS2NS(hopt->buffer);
+	cl->cbuffer = PSCHED_TICKS2NS(hopt->cbuffer);
+
+	sch_tree_unlock(sch);
+
+	qdisc_class_hash_grow(sch, &q->clhash);
+
+	*arg = (unsigned long)cl;
+	return 0;
+
+failure:
+	return err;
+}
+
+static struct tcf_proto __rcu **htb_find_tcf(struct Qdisc *sch,
+					     unsigned long arg)
+{
+	struct htb_sched *q = qdisc_priv(sch);
+	struct htb_class *cl = (struct htb_class *)arg;
+	struct tcf_proto __rcu **fl = cl ? &cl->filter_list : &q->filter_list;
+
+	return fl;
+}
+
+static unsigned long htb_bind_filter(struct Qdisc *sch, unsigned long parent,
+				     u32 classid)
+{
+	struct htb_class *cl = htb_find(classid, sch);
+
+	/*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++;
+	return (unsigned long)cl;
+}
+
+static void htb_unbind_filter(struct Qdisc *sch, unsigned long arg)
+{
+	struct htb_class *cl = (struct htb_class *)arg;
+
+	if (cl)
+		cl->filter_cnt--;
+}
+
+static void htb_walk(struct Qdisc *sch, struct qdisc_walker *arg)
+{
+	struct htb_sched *q = qdisc_priv(sch);
+	struct htb_class *cl;
+	unsigned int i;
+
+	if (arg->stop)
+		return;
+
+	for (i = 0; i < q->clhash.hashsize; i++) {
+		hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
+			if (arg->count < arg->skip) {
+				arg->count++;
+				continue;
+			}
+			if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
+				arg->stop = 1;
+				return;
+			}
+			arg->count++;
+		}
+	}
+}
+
+static const struct Qdisc_class_ops htb_class_ops = {
+	.graft		=	htb_graft,
+	.leaf		=	htb_leaf,
+	.qlen_notify	=	htb_qlen_notify,
+	.get		=	htb_get,
+	.put		=	htb_put,
+	.change		=	htb_change_class,
+	.delete		=	htb_delete,
+	.walk		=	htb_walk,
+	.tcf_chain	=	htb_find_tcf,
+	.bind_tcf	=	htb_bind_filter,
+	.unbind_tcf	=	htb_unbind_filter,
+	.dump		=	htb_dump_class,
+	.dump_stats	=	htb_dump_class_stats,
+};
+
+static struct Qdisc_ops htb_qdisc_ops __read_mostly = {
+	.cl_ops		=	&htb_class_ops,
+	.id		=	"htb",
+	.priv_size	=	sizeof(struct htb_sched),
+	.enqueue	=	htb_enqueue,
+	.dequeue	=	htb_dequeue,
+	.peek		=	qdisc_peek_dequeued,
+	.drop		=	htb_drop,
+	.init		=	htb_init,
+	.reset		=	htb_reset,
+	.destroy	=	htb_destroy,
+	.dump		=	htb_dump,
+	.owner		=	THIS_MODULE,
+};
+
+static int __init htb_module_init(void)
+{
+	return register_qdisc(&htb_qdisc_ops);
+}
+static void __exit htb_module_exit(void)
+{
+	unregister_qdisc(&htb_qdisc_ops);
+}
+
+module_init(htb_module_init)
+module_exit(htb_module_exit)
+MODULE_LICENSE("GPL");