--- a/include/linux/pkt_sched.h	2011-02-28 13:28:57.763177314 -0800
+++ b/include/linux/pkt_sched.h	2011-02-28 13:29:10.466792117 -0800
@@ -588,4 +588,18 @@ struct tc_sfb_xstats {
 
 #define SFB_MAX_PROB 0xFFFF
 
+/* QFQ */
+enum {
+	TCA_QFQ_WEIGHT,
+	TCA_QFQ_LMAX,
+	__TCA_QFQ_MAX
+};
+
+#define TCA_QFQ_MAX	(__TCA_QFQ_MAX - 1)
+
+struct tc_qfq_stats {
+	__u32 weight;
+	__u32 lmax;
+};
+
 #endif
--- a/net/sched/Kconfig	2011-02-28 13:28:57.771177070 -0800
+++ b/net/sched/Kconfig	2011-02-28 17:13:01.119718271 -0800
@@ -239,6 +239,17 @@ config NET_SCH_CHOKE
 	  To compile this code as a module, choose M here: the
 	  module will be called sch_choke.
 
+config NET_SCH_QFQ
+	tristate "Quick Fair Queueing scheduler (QFQ)"
+	help
+	  Say Y here if you want to use the Quick Fair Queueing Scheduler (QFQ)
+	  packet scheduling algorithm.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called sch_qfq.
+
+	  If unsure, say N.
+
 config NET_SCH_INGRESS
 	tristate "Ingress Qdisc"
 	depends on NET_CLS_ACT
--- a/net/sched/Makefile	2011-02-28 13:28:57.783176704 -0800
+++ b/net/sched/Makefile	2011-02-28 13:29:10.470791996 -0800
@@ -35,6 +35,7 @@ obj-$(CONFIG_NET_SCH_NETEM)	+= sch_netem
 obj-$(CONFIG_NET_SCH_DRR)	+= sch_drr.o
 obj-$(CONFIG_NET_SCH_MQPRIO)	+= sch_mqprio.o
 obj-$(CONFIG_NET_SCH_CHOKE)	+= sch_choke.o
+obj-$(CONFIG_NET_SCH_QFQ)	+= sch_qfq.o
 
 obj-$(CONFIG_NET_CLS_U32)	+= cls_u32.o
 obj-$(CONFIG_NET_CLS_ROUTE4)	+= cls_route.o
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ b/net/sched/sch_qfq.c	2011-02-28 17:10:48.961445894 -0800
@@ -0,0 +1,1124 @@
+/*
+ * net/sched/sch_qfq.c         Quick Fair Queueing Scheduler.
+ *
+ * Copyright (c) 2009 Fabio Checconi, Luigi Rizzo, and Paolo Valente.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/netdevice.h>
+#include <linux/pkt_sched.h>
+#include <net/sch_generic.h>
+#include <net/pkt_sched.h>
+#include <net/pkt_cls.h>
+
+
+/*  Quick Fair Queueing
+    ===================
+
+    Sources:
+    Fabio Checconi and Scuola Superiore and S. Anna
+    and Paolo Valente and Luigi Riz "QFQ: Efficient Packet Scheduling
+    with Tight Bandwidth Distribution Guarantees"
+
+    See also:
+    http://retis.sssup.it/~fabio/linux/qfq/
+ */
+
+/*
+
+  Virtual time computations.
+
+  S, F and V are all computed in fixed point arithmetic with
+  FRAC_BITS decimal bits.
+
+  QFQ_MAX_INDEX is the maximum index allowed for a group. We need
+	one bit per index.
+  QFQ_MAX_WSHIFT is the maximum power of two supported as a weight.
+
+  The layout of the bits is as below:
+
+                   [ MTU_SHIFT ][      FRAC_BITS    ]
+                   [ MAX_INDEX    ][ MIN_SLOT_SHIFT ]
+				 ^.__grp->index = 0
+				 *.__grp->slot_shift
+
+  where MIN_SLOT_SHIFT is derived by difference from the others.
+
+  The max group index corresponds to Lmax/w_min, where
+  Lmax=1<<MTU_SHIFT, w_min = 1 .
+  From this, and knowing how many groups (MAX_INDEX) we want,
+  we can derive the shift corresponding to each group.
+
+  Because we often need to compute
+	F = S + len/w_i  and V = V + len/wsum
+  instead of storing w_i store the value
+	inv_w = (1<<FRAC_BITS)/w_i
+  so we can do F = S + len * inv_w * wsum.
+  We use W_TOT in the formulas so we can easily move between
+  static and adaptive weight sum.
+
+  The per-scheduler-instance data contain all the data structures
+  for the scheduler: bitmaps and bucket lists.
+
+ */
+
+/*
+ * Maximum number of consecutive slots occupied by backlogged classes
+ * inside a group.
+ */
+#define QFQ_MAX_SLOTS	32
+
+/*
+ * Shifts used for class<->group mapping.  We allow class weights that are
+ * in the range [1, 2^MAX_WSHIFT], and we try to map each class i to the
+ * group with the smallest index that can support the L_i / r_i configured
+ * for the class.
+ *
+ * grp->index is the index of the group; and grp->slot_shift
+ * is the shift for the corresponding (scaled) sigma_i.
+ */
+#define QFQ_MAX_INDEX		19
+#define QFQ_MAX_WSHIFT		16
+
+#define	QFQ_MAX_WEIGHT		(1<<QFQ_MAX_WSHIFT)
+#define QFQ_MAX_WSUM		(2*QFQ_MAX_WEIGHT)
+
+#define FRAC_BITS		30	/* fixed point arithmetic */
+#define ONE_FP			(1UL << FRAC_BITS)
+#define IWSUM			(ONE_FP/QFQ_MAX_WSUM)
+
+#define QFQ_MTU_SHIFT		11
+#define QFQ_MIN_SLOT_SHIFT	(FRAC_BITS + QFQ_MTU_SHIFT - QFQ_MAX_INDEX)
+
+/*
+ * Possible group states.  These values are used as indexes for the bitmaps
+ * array of struct qfq_queue.
+ */
+enum qfq_state { ER, IR, EB, IB, QFQ_MAX_STATE };
+
+struct qfq_group;
+
+struct qfq_class {
+	struct Qdisc_class_common common;
+
+	unsigned int refcnt;
+	unsigned int filter_cnt;
+
+	struct gnet_stats_basic_packed bstats;
+	struct gnet_stats_queue qstats;
+	struct gnet_stats_rate_est rate_est;
+	struct Qdisc *qdisc;
+
+	struct qfq_class *next;	/* Link for the slot list. */
+	u64 S, F;		/* flow timestamps (exact) */
+
+	/* group we belong to. In principle we would need the index,
+	 * which is log_2(lmax/weight), but we never reference it
+	 * directly, only the group.
+	 */
+	struct qfq_group *grp;
+
+	/* these are copied from the flowset. */
+	u32	inv_w;		/* ONE_FP/weight */
+	u32	lmax;		/* Max packet size for this flow. */
+};
+
+struct qfq_group {
+	u64 S, F;			/* group timestamps (approx). */
+	unsigned int slot_shift;	/* Slot shift. */
+	unsigned int index;		/* Group index. */
+	unsigned int front;		/* Index of the front slot. */
+	unsigned long full_slots;	/* non-empty slots */
+
+	/* Array of RR lists of active classes. */
+	struct qfq_class *slots[QFQ_MAX_SLOTS];
+};
+
+struct qfq_sched {
+	struct tcf_proto *filter_list;
+	struct Qdisc_class_hash clhash;
+
+	u64		V;		/* Precise virtual time. */
+	u32		wsum;		/* weight sum */
+
+	unsigned long bitmaps[QFQ_MAX_STATE];	    /* Group bitmaps. */
+	struct qfq_group groups[QFQ_MAX_INDEX + 1]; /* The groups. */
+};
+
+static struct qfq_class *qfq_find_class(struct Qdisc *sch, u32 classid)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct Qdisc_class_common *clc;
+
+	clc = qdisc_class_find(&q->clhash, classid);
+	if (clc == NULL)
+		return NULL;
+	return container_of(clc, struct qfq_class, common);
+}
+
+static void qfq_purge_queue(struct qfq_class *cl)
+{
+	unsigned int len = cl->qdisc->q.qlen;
+
+	qdisc_reset(cl->qdisc);
+	qdisc_tree_decrease_qlen(cl->qdisc, len);
+}
+
+static const struct nla_policy qfq_policy[TCA_QFQ_MAX + 1] = {
+	[TCA_QFQ_WEIGHT] = { .type = NLA_U32 },
+	[TCA_QFQ_LMAX] = { .type = NLA_U32 },
+};
+
+/*
+ * Calculate a flow index, given its weight and maximum packet length.
+ * index = log_2(maxlen/weight) but we need to apply the scaling.
+ * This is used only once at flow creation.
+ */
+static int qfq_calc_index(u32 inv_w, unsigned int maxlen)
+{
+	u64 slot_size = (u64)maxlen * inv_w;
+	unsigned long size_map;
+	int index = 0;
+
+	size_map = slot_size >> QFQ_MIN_SLOT_SHIFT;
+	if (!size_map)
+		goto out;
+
+	index = __fls(size_map) + 1;	/* basically a log_2 */
+	index -= !(slot_size - (1ULL << (index + QFQ_MIN_SLOT_SHIFT - 1)));
+
+	if (index < 0)
+		index = 0;
+out:
+	pr_debug("qfq calc_index: W = %lu, L = %u, I = %d\n",
+		 (unsigned long) ONE_FP/inv_w, maxlen, index);
+
+	return index;
+}
+
+static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
+			    struct nlattr **tca, unsigned long *arg)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_class *cl = (struct qfq_class *)*arg;
+	struct nlattr *tb[TCA_QFQ_MAX + 1];
+	u32 weight, lmax, inv_w;
+	int i, err;
+
+	if (tca[TCA_OPTIONS] == NULL)
+		return -EINVAL;
+
+	err = nla_parse_nested(tb, TCA_QFQ_MAX, tca[TCA_OPTIONS], qfq_policy);
+	if (err < 0)
+		return err;
+
+	if (tb[TCA_QFQ_WEIGHT]) {
+		weight = nla_get_u32(tb[TCA_QFQ_WEIGHT]);
+		if (!weight || weight > (1UL << QFQ_MAX_WSHIFT)) {
+			pr_notice("qfq: invalid weight %u\n", weight);
+			return -EINVAL;
+		}
+	} else
+		weight = 1;
+
+	inv_w = ONE_FP / weight;
+	weight = ONE_FP / inv_w;
+	if (q->wsum + weight > QFQ_MAX_WSUM) {
+		pr_notice("qfq: total weight out of range (%u + %u)\n",
+			  weight, q->wsum);
+		return -EINVAL;
+	}
+
+	if (tb[TCA_QFQ_LMAX]) {
+		lmax = nla_get_u32(tb[TCA_QFQ_LMAX]);
+		if (!lmax || lmax > (1UL << QFQ_MTU_SHIFT)) {
+			pr_notice("qfq: invalid max length %u\n", lmax);
+			return -EINVAL;
+		}
+	} else
+		lmax = 1UL << QFQ_MTU_SHIFT;
+
+	if (cl != NULL) {
+		if (tca[TCA_RATE]) {
+			err = gen_replace_estimator(&cl->bstats, &cl->rate_est,
+						    qdisc_root_sleeping_lock(sch),
+						    tca[TCA_RATE]);
+			if (err)
+				return err;
+		}
+
+		sch_tree_lock(sch);
+		if (tb[TCA_QFQ_WEIGHT]) {
+			q->wsum = weight - ONE_FP / cl->inv_w;
+			cl->inv_w = inv_w;
+		}
+		sch_tree_unlock(sch);
+
+		return 0;
+	}
+
+	cl = kzalloc(sizeof(struct qfq_class), GFP_KERNEL);
+	if (cl == NULL)
+		return -ENOBUFS;
+
+	cl->refcnt = 1;
+	cl->common.classid = classid;
+	cl->lmax = lmax;
+	cl->inv_w = inv_w;
+	i = qfq_calc_index(cl->inv_w, cl->lmax);
+
+	cl->grp = &q->groups[i];
+	q->wsum += weight;
+
+	cl->qdisc = qdisc_create_dflt(sch->dev_queue,
+				      &pfifo_qdisc_ops, classid);
+	if (cl->qdisc == NULL)
+		cl->qdisc = &noop_qdisc;
+
+	if (tca[TCA_RATE]) {
+		err = gen_new_estimator(&cl->bstats, &cl->rate_est,
+					qdisc_root_sleeping_lock(sch),
+					tca[TCA_RATE]);
+		if (err) {
+			qdisc_destroy(cl->qdisc);
+			kfree(cl);
+			return err;
+		}
+	}
+
+	sch_tree_lock(sch);
+	qdisc_class_hash_insert(&q->clhash, &cl->common);
+	sch_tree_unlock(sch);
+
+	qdisc_class_hash_grow(sch, &q->clhash);
+
+	*arg = (unsigned long)cl;
+	return 0;
+}
+
+static void qfq_destroy_class(struct Qdisc *sch, struct qfq_class *cl)
+{
+	struct qfq_sched *q = (struct qfq_sched *)sch;
+
+	if (cl->inv_w) {
+		q->wsum -= ONE_FP / cl->inv_w;
+		cl->inv_w = 0;
+	}
+
+	gen_kill_estimator(&cl->bstats, &cl->rate_est);
+	qdisc_destroy(cl->qdisc);
+	kfree(cl);
+}
+
+static int qfq_delete_class(struct Qdisc *sch, unsigned long arg)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_class *cl = (struct qfq_class *)arg;
+
+	if (cl->filter_cnt > 0)
+		return -EBUSY;
+
+	sch_tree_lock(sch);
+
+	qfq_purge_queue(cl);
+	qdisc_class_hash_remove(&q->clhash, &cl->common);
+
+	if (--cl->refcnt == 0)
+		qfq_destroy_class(sch, cl);
+
+	sch_tree_unlock(sch);
+	return 0;
+}
+
+static unsigned long qfq_get_class(struct Qdisc *sch, u32 classid)
+{
+	struct qfq_class *cl = qfq_find_class(sch, classid);
+
+	if (cl != NULL)
+		cl->refcnt++;
+
+	return (unsigned long)cl;
+}
+
+static void qfq_put_class(struct Qdisc *sch, unsigned long arg)
+{
+	struct qfq_class *cl = (struct qfq_class *)arg;
+
+	if (--cl->refcnt == 0)
+		qfq_destroy_class(sch, cl);
+}
+
+static struct tcf_proto **qfq_tcf_chain(struct Qdisc *sch, unsigned long cl)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+
+	if (cl)
+		return NULL;
+
+	return &q->filter_list;
+}
+
+static unsigned long qfq_bind_tcf(struct Qdisc *sch, unsigned long parent,
+				  u32 classid)
+{
+	struct qfq_class *cl = qfq_find_class(sch, classid);
+
+	if (cl != NULL)
+		cl->filter_cnt++;
+
+	return (unsigned long)cl;
+}
+
+static void qfq_unbind_tcf(struct Qdisc *sch, unsigned long arg)
+{
+	struct qfq_class *cl = (struct qfq_class *)arg;
+
+	cl->filter_cnt--;
+}
+
+static int qfq_graft_class(struct Qdisc *sch, unsigned long arg,
+			   struct Qdisc *new, struct Qdisc **old)
+{
+	struct qfq_class *cl = (struct qfq_class *)arg;
+
+	if (new == NULL) {
+		new = qdisc_create_dflt(sch->dev_queue,
+					&pfifo_qdisc_ops, cl->common.classid);
+		if (new == NULL)
+			new = &noop_qdisc;
+	}
+
+	sch_tree_lock(sch);
+	qfq_purge_queue(cl);
+	*old = cl->qdisc;
+	cl->qdisc = new;
+	sch_tree_unlock(sch);
+	return 0;
+}
+
+static struct Qdisc *qfq_class_leaf(struct Qdisc *sch, unsigned long arg)
+{
+	struct qfq_class *cl = (struct qfq_class *)arg;
+
+	return cl->qdisc;
+}
+
+static int qfq_dump_class(struct Qdisc *sch, unsigned long arg,
+			  struct sk_buff *skb, struct tcmsg *tcm)
+{
+	struct qfq_class *cl = (struct qfq_class *)arg;
+	struct nlattr *nest;
+
+	tcm->tcm_parent	= TC_H_ROOT;
+	tcm->tcm_handle	= cl->common.classid;
+	tcm->tcm_info	= cl->qdisc->handle;
+
+	nest = nla_nest_start(skb, TCA_OPTIONS);
+	if (nest == NULL)
+		goto nla_put_failure;
+	NLA_PUT_U32(skb, TCA_QFQ_WEIGHT, ONE_FP/cl->inv_w);
+	NLA_PUT_U32(skb, TCA_QFQ_LMAX, cl->lmax);
+	return nla_nest_end(skb, nest);
+
+nla_put_failure:
+	nla_nest_cancel(skb, nest);
+	return -EMSGSIZE;
+}
+
+static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg,
+				struct gnet_dump *d)
+{
+	struct qfq_class *cl = (struct qfq_class *)arg;
+	struct tc_qfq_stats xstats;
+
+	memset(&xstats, 0, sizeof(xstats));
+
+	xstats.weight = ONE_FP/cl->inv_w;
+	xstats.lmax = cl->lmax;
+
+	if (gnet_stats_copy_basic(d, &cl->bstats) < 0 ||
+	    gnet_stats_copy_rate_est(d, NULL, &cl->rate_est) < 0 ||
+	    gnet_stats_copy_queue(d, &cl->qdisc->qstats) < 0)
+		return -1;
+
+	return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
+}
+
+static void qfq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_class *cl;
+	struct hlist_node *n;
+	unsigned int i;
+
+	if (arg->stop)
+		return;
+
+	for (i = 0; i < q->clhash.hashsize; i++) {
+		hlist_for_each_entry(cl, n, &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 struct qfq_class *qfq_classify(struct sk_buff *skb, struct Qdisc *sch,
+				      int *qerr)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_class *cl;
+	struct tcf_result res;
+	int result;
+
+	if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
+		pr_debug("qfq_classify: found %d\n", skb->priority);
+		cl = qfq_find_class(sch, skb->priority);
+		if (cl != NULL)
+			return cl;
+	}
+
+	*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
+	result = tc_classify(skb, q->filter_list, &res);
+	if (result >= 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 = (struct qfq_class *)res.class;
+		if (cl == NULL)
+			cl = qfq_find_class(sch, res.classid);
+		return cl;
+	}
+
+	return NULL;
+}
+
+/* Generic comparison function, handling wraparound. */
+static inline int qfq_gt(u64 a, u64 b)
+{
+	return (s64)(a - b) > 0;
+}
+
+/* Round a precise timestamp to its slotted value. */
+static inline u64 qfq_round_down(u64 ts, unsigned int shift)
+{
+	return ts & ~((1ULL << shift) - 1);
+}
+
+/* return the pointer to the group with lowest index in the bitmap */
+static inline struct qfq_group *qfq_ffs(struct qfq_sched *q,
+					unsigned long bitmap)
+{
+	int index = __ffs(bitmap);
+	return &q->groups[index];
+}
+/* Calculate a mask to mimic what would be ffs_from(). */
+static inline unsigned long mask_from(unsigned long bitmap, int from)
+{
+	return bitmap & ~((1UL << from) - 1);
+}
+
+/*
+ * The state computation relies on ER=0, IR=1, EB=2, IB=3
+ * First compute eligibility comparing grp->S, q->V,
+ * then check if someone is blocking us and possibly add EB
+ */
+static int qfq_calc_state(struct qfq_sched *q, const struct qfq_group *grp)
+{
+	/* if S > V we are not eligible */
+	unsigned int state = qfq_gt(grp->S, q->V);
+	unsigned long mask = mask_from(q->bitmaps[ER], grp->index);
+	struct qfq_group *next;
+
+	if (mask) {
+		next = qfq_ffs(q, mask);
+		if (qfq_gt(grp->F, next->F))
+			state |= EB;
+	}
+
+	return state;
+}
+
+
+/*
+ * In principle
+ *	q->bitmaps[dst] |= q->bitmaps[src] & mask;
+ *	q->bitmaps[src] &= ~mask;
+ * but we should make sure that src != dst
+ */
+static inline void qfq_move_groups(struct qfq_sched *q, unsigned long mask,
+				   int src, int dst)
+{
+	q->bitmaps[dst] |= q->bitmaps[src] & mask;
+	q->bitmaps[src] &= ~mask;
+}
+
+static void qfq_unblock_groups(struct qfq_sched *q, int index, u64 old_F)
+{
+	unsigned long mask = mask_from(q->bitmaps[ER], index + 1);
+	struct qfq_group *next;
+
+	if (mask) {
+		next = qfq_ffs(q, mask);
+		if (!qfq_gt(next->F, old_F))
+			return;
+	}
+
+	mask = (1UL << index) - 1;
+	qfq_move_groups(q, mask, EB, ER);
+	qfq_move_groups(q, mask, IB, IR);
+}
+
+/*
+ * perhaps
+ *
+	old_V ^= q->V;
+	old_V >>= QFQ_MIN_SLOT_SHIFT;
+	if (old_V) {
+		...
+	}
+ *
+ */
+static void qfq_make_eligible(struct qfq_sched *q, u64 old_V)
+{
+	unsigned long vslot = q->V >> QFQ_MIN_SLOT_SHIFT;
+	unsigned long old_vslot = old_V >> QFQ_MIN_SLOT_SHIFT;
+
+	if (vslot != old_vslot) {
+		unsigned long mask = (1UL << fls(vslot ^ old_vslot)) - 1;
+		qfq_move_groups(q, mask, IR, ER);
+		qfq_move_groups(q, mask, IB, EB);
+	}
+}
+
+/*
+ * XXX we should make sure that slot becomes less than 32.
+ * This is guaranteed by the input values.
+ * roundedS is always cl->S rounded on grp->slot_shift bits.
+ */
+static void qfq_slot_insert(struct qfq_group *grp, struct qfq_class *cl,
+				   u64 roundedS)
+{
+	u64 slot = (roundedS - grp->S) >> grp->slot_shift;
+	unsigned int i = (grp->front + slot) % QFQ_MAX_SLOTS;
+
+	cl->next = grp->slots[i];
+	grp->slots[i] = cl;
+	__set_bit(slot, &grp->full_slots);
+}
+
+/*
+ * remove the entry from the slot
+ */
+static void qfq_front_slot_remove(struct qfq_group *grp)
+{
+	struct qfq_class **h = &grp->slots[grp->front];
+
+	*h = (*h)->next;
+	if (!*h)
+		__clear_bit(0, &grp->full_slots);
+}
+
+/*
+ * Returns the first full queue in a group. As a side effect,
+ * adjust the bucket list so the first non-empty bucket is at
+ * position 0 in full_slots.
+ */
+static struct qfq_class *qfq_slot_scan(struct qfq_group *grp)
+{
+	unsigned int i;
+
+	pr_debug("qfq slot_scan: grp %u full %#lx\n",
+		 grp->index, grp->full_slots);
+
+	if (grp->full_slots == 0)
+		return NULL;
+
+	i = __ffs(grp->full_slots);  /* zero based */
+	if (i > 0) {
+		grp->front = (grp->front + i) % QFQ_MAX_SLOTS;
+		grp->full_slots >>= i;
+	}
+
+	return grp->slots[grp->front];
+}
+
+/*
+ * adjust the bucket list. When the start time of a group decreases,
+ * we move the index down (modulo QFQ_MAX_SLOTS) so we don't need to
+ * move the objects. The mask of occupied slots must be shifted
+ * because we use ffs() to find the first non-empty slot.
+ * This covers decreases in the group's start time, but what about
+ * increases of the start time ?
+ * Here too we should make sure that i is less than 32
+ */
+static void qfq_slot_rotate(struct qfq_group *grp, u64 roundedS)
+{
+	unsigned int i = (grp->S - roundedS) >> grp->slot_shift;
+
+	grp->full_slots <<= i;
+	grp->front = (grp->front - i) % QFQ_MAX_SLOTS;
+}
+
+static void qfq_update_eligible(struct qfq_sched *q, u64 old_V)
+{
+	struct qfq_group *grp;
+	unsigned long ineligible;
+
+	ineligible = q->bitmaps[IR] | q->bitmaps[IB];
+	if (ineligible) {
+		if (!q->bitmaps[ER]) {
+			grp = qfq_ffs(q, ineligible);
+			if (qfq_gt(grp->S, q->V))
+				q->V = grp->S;
+		}
+		qfq_make_eligible(q, old_V);
+	}
+}
+
+/* What is length of next packet in queue (0 if queue is empty) */
+static unsigned int qdisc_peek_len(struct Qdisc *sch)
+{
+	struct sk_buff *skb;
+
+	skb = sch->ops->peek(sch);
+	return skb ? qdisc_pkt_len(skb) : 0;
+}
+
+/*
+ * Updates the class, returns true if also the group needs to be updated.
+ */
+static bool qfq_update_class(struct qfq_group *grp, struct qfq_class *cl)
+{
+	unsigned int len = qdisc_peek_len(cl->qdisc);
+
+	cl->S = cl->F;
+	if (!len)
+		qfq_front_slot_remove(grp);	/* queue is empty */
+	else {
+		u64 roundedS;
+
+		cl->F = cl->S + (u64)len * cl->inv_w;
+		roundedS = qfq_round_down(cl->S, grp->slot_shift);
+		if (roundedS == grp->S)
+			return false;
+
+		qfq_front_slot_remove(grp);
+		qfq_slot_insert(grp, cl, roundedS);
+	}
+
+	return true;
+}
+
+static struct sk_buff *qfq_dequeue(struct Qdisc *sch)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_group *grp;
+	struct qfq_class *cl;
+	struct sk_buff *skb;
+	unsigned int len;
+	u64 old_V;
+
+	if (!q->bitmaps[ER])
+		return NULL;
+
+	grp = qfq_ffs(q, q->bitmaps[ER]);
+
+	cl = grp->slots[grp->front];
+	skb = qdisc_dequeue_peeked(cl->qdisc);
+	if (!skb) {
+		WARN_ONCE(1, "qfq_dequeue: non-workconserving leaf\n");
+		return NULL;
+	}
+
+	sch->q.qlen--;
+	qdisc_bstats_update(sch, skb);
+
+	old_V = q->V;
+	len = qdisc_pkt_len(skb);
+	q->V += (u64)len * IWSUM;
+	pr_debug("qfq dequeue: len %u F %lld now %lld\n",
+		 len, (unsigned long long) cl->F, (unsigned long long) q->V);
+
+	if (qfq_update_class(grp, cl)) {
+		u64 old_F = grp->F;
+
+		cl = qfq_slot_scan(grp);
+		if (!cl)
+			__clear_bit(grp->index, &q->bitmaps[ER]);
+		else {
+			u64 roundedS = qfq_round_down(cl->S, grp->slot_shift);
+			unsigned int s;
+
+			if (grp->S == roundedS)
+				goto skip_unblock;
+			grp->S = roundedS;
+			grp->F = roundedS + (2ULL << grp->slot_shift);
+			__clear_bit(grp->index, &q->bitmaps[ER]);
+			s = qfq_calc_state(q, grp);
+			__set_bit(grp->index, &q->bitmaps[s]);
+		}
+
+		qfq_unblock_groups(q, grp->index, old_F);
+	}
+
+skip_unblock:
+	qfq_update_eligible(q, old_V);
+
+	return skb;
+}
+
+/*
+ * Assign a reasonable start time for a new flow k in group i.
+ * Admissible values for \hat(F) are multiples of \sigma_i
+ * no greater than V+\sigma_i . Larger values mean that
+ * we had a wraparound so we consider the timestamp to be stale.
+ *
+ * If F is not stale and F >= V then we set S = F.
+ * Otherwise we should assign S = V, but this may violate
+ * the ordering in ER. So, if we have groups in ER, set S to
+ * the F_j of the first group j which would be blocking us.
+ * We are guaranteed not to move S backward because
+ * otherwise our group i would still be blocked.
+ */
+static void qfq_update_start(struct qfq_sched *q, struct qfq_class *cl)
+{
+	unsigned long mask;
+	uint32_t limit, roundedF;
+	int slot_shift = cl->grp->slot_shift;
+
+	roundedF = qfq_round_down(cl->F, slot_shift);
+	limit = qfq_round_down(q->V, slot_shift) + (1UL << slot_shift);
+
+	if (!qfq_gt(cl->F, q->V) || qfq_gt(roundedF, limit)) {
+		/* timestamp was stale */
+		mask = mask_from(q->bitmaps[ER], cl->grp->index);
+		if (mask) {
+			struct qfq_group *next = qfq_ffs(q, mask);
+			if (qfq_gt(roundedF, next->F)) {
+				cl->S = next->F;
+				return;
+			}
+		}
+		cl->S = q->V;
+	} else  /* timestamp is not stale */
+		cl->S = cl->F;
+}
+
+static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_group *grp;
+	struct qfq_class *cl;
+	int err;
+	u64 roundedS;
+	int s;
+
+	cl = qfq_classify(skb, sch, &err);
+	if (cl == NULL) {
+		if (err & __NET_XMIT_BYPASS)
+			sch->qstats.drops++;
+		kfree_skb(skb);
+		return err;
+	}
+	pr_debug("qfq_enqueue: cl = %x\n", cl->common.classid);
+
+	err = qdisc_enqueue(skb, cl->qdisc);
+	if (unlikely(err != NET_XMIT_SUCCESS)) {
+		pr_debug("qfq_enqueue: enqueue failed %d\n", err);
+		if (net_xmit_drop_count(err)) {
+			cl->qstats.drops++;
+			sch->qstats.drops++;
+		}
+		return err;
+	}
+
+	bstats_update(&cl->bstats, skb);
+	++sch->q.qlen;
+
+	/* If the new skb is not the head of queue, then done here. */
+	if (skb != qdisc_peek_head(cl->qdisc))
+		return err;
+
+	/* If reach this point, queue q was idle */
+	grp = cl->grp;
+	qfq_update_start(q, cl);
+
+	/* compute new finish time and rounded start. */
+	cl->F = cl->S + (u64)qdisc_pkt_len(skb) * cl->inv_w;
+	roundedS = qfq_round_down(cl->S, grp->slot_shift);
+
+	/*
+	 * insert cl in the correct bucket.
+	 * If cl->S >= grp->S we don't need to adjust the
+	 * bucket list and simply go to the insertion phase.
+	 * Otherwise grp->S is decreasing, we must make room
+	 * in the bucket list, and also recompute the group state.
+	 * Finally, if there were no flows in this group and nobody
+	 * was in ER make sure to adjust V.
+	 */
+	if (grp->full_slots) {
+		if (!qfq_gt(grp->S, cl->S))
+			goto skip_update;
+
+		/* create a slot for this cl->S */
+		qfq_slot_rotate(grp, roundedS);
+		/* group was surely ineligible, remove */
+		__clear_bit(grp->index, &q->bitmaps[IR]);
+		__clear_bit(grp->index, &q->bitmaps[IB]);
+	} else if (!q->bitmaps[ER] && qfq_gt(roundedS, q->V))
+		q->V = roundedS;
+
+	grp->S = roundedS;
+	grp->F = roundedS + (2ULL << grp->slot_shift);
+	s = qfq_calc_state(q, grp);
+	__set_bit(grp->index, &q->bitmaps[s]);
+
+	pr_debug("qfq enqueue: new state %d %#lx S %lld F %lld V %lld\n",
+		 s, q->bitmaps[s],
+		 (unsigned long long) cl->S,
+		 (unsigned long long) cl->F,
+		 (unsigned long long) q->V);
+
+skip_update:
+	qfq_slot_insert(grp, cl, roundedS);
+
+	return err;
+}
+
+
+static void qfq_slot_remove(struct qfq_sched *q, struct qfq_group *grp,
+			    struct qfq_class *cl, struct qfq_class **pprev)
+{
+	unsigned int i, offset;
+	u64 roundedS;
+
+	roundedS = qfq_round_down(cl->S, grp->slot_shift);
+	offset = (roundedS - grp->S) >> grp->slot_shift;
+	i = (grp->front + offset) % QFQ_MAX_SLOTS;
+
+	if (!pprev) {
+		pprev = &grp->slots[i];
+		while (*pprev && *pprev != cl)
+			pprev = &(*pprev)->next;
+	}
+
+	*pprev = cl->next;
+	if (!grp->slots[i])
+		__clear_bit(offset, &grp->full_slots);
+}
+
+/*
+ * called to forcibly destroy a queue.
+ * If the queue is not in the front bucket, or if it has
+ * other queues in the front bucket, we can simply remove
+ * the queue with no other side effects.
+ * Otherwise we must propagate the event up.
+ */
+static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl,
+				 struct qfq_class **pprev)
+{
+	struct qfq_group *grp = cl->grp;
+	unsigned long mask;
+	u64 roundedS;
+	int s;
+
+	cl->F = cl->S;
+	qfq_slot_remove(q, grp, cl, pprev);
+
+	if (!grp->full_slots) {
+		__clear_bit(grp->index, &q->bitmaps[IR]);
+		__clear_bit(grp->index, &q->bitmaps[EB]);
+		__clear_bit(grp->index, &q->bitmaps[IB]);
+
+		if (test_bit(grp->index, &q->bitmaps[ER]) &&
+		    !(q->bitmaps[ER] & ~((1UL << grp->index) - 1))) {
+			mask = q->bitmaps[ER] & ((1UL << grp->index) - 1);
+			if (mask)
+				mask = ~((1UL << __fls(mask)) - 1);
+			else
+				mask = ~0UL;
+			qfq_move_groups(q, mask, EB, ER);
+			qfq_move_groups(q, mask, IB, IR);
+		}
+		__clear_bit(grp->index, &q->bitmaps[ER]);
+	} else if (!grp->slots[grp->front]) {
+		cl = qfq_slot_scan(grp);
+		roundedS = qfq_round_down(cl->S, grp->slot_shift);
+		if (grp->S != roundedS) {
+			__clear_bit(grp->index, &q->bitmaps[ER]);
+			__clear_bit(grp->index, &q->bitmaps[IR]);
+			__clear_bit(grp->index, &q->bitmaps[EB]);
+			__clear_bit(grp->index, &q->bitmaps[IB]);
+			grp->S = roundedS;
+			grp->F = roundedS + (2ULL << grp->slot_shift);
+			s = qfq_calc_state(q, grp);
+			__set_bit(grp->index, &q->bitmaps[s]);
+		}
+	}
+
+	qfq_update_eligible(q, q->V);
+}
+
+static void qfq_qlen_notify(struct Qdisc *sch, unsigned long arg)
+{
+	struct qfq_sched *q = (struct qfq_sched *)sch;
+	struct qfq_class *cl = (struct qfq_class *)arg;
+
+	if (cl->qdisc->q.qlen == 0)
+		qfq_deactivate_class(q, cl, NULL);
+}
+
+static unsigned int qfq_drop(struct Qdisc *sch)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_group *grp;
+	struct qfq_class *cl, **pp;
+	unsigned int i, j, len;
+
+	for (i = 0; i <= QFQ_MAX_INDEX; i++) {
+		grp = &q->groups[i];
+		for (j = 0; j < QFQ_MAX_SLOTS; j++) {
+			for (pp = &grp->slots[j]; *pp; pp = &(*pp)->next) {
+				cl = *pp;
+				if (!cl->qdisc->ops->drop)
+					continue;
+
+				len = cl->qdisc->ops->drop(cl->qdisc);
+				if (len > 0) {
+					sch->q.qlen--;
+					if (!cl->qdisc->q.qlen)
+						qfq_deactivate_class(q, cl, pp);
+
+					return len;
+				}
+			}
+		}
+	}
+
+	return 0;
+}
+
+static int qfq_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_group *grp;
+	int i, err;
+
+	err = qdisc_class_hash_init(&q->clhash);
+	if (err < 0)
+		return err;
+
+	for (i = 0; i <= QFQ_MAX_INDEX; i++) {
+		grp = &q->groups[i];
+		grp->index = i;
+	}
+
+	return 0;
+}
+
+static void qfq_reset_qdisc(struct Qdisc *sch)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_group *grp;
+	struct qfq_class *cl, **pp;
+	struct hlist_node *n;
+	unsigned int i, j;
+
+	for (i = 0; i <= QFQ_MAX_INDEX; i++) {
+		grp = &q->groups[i];
+		for (j = 0; j < QFQ_MAX_SLOTS; j++) {
+			for (pp = &grp->slots[j]; *pp; pp = &(*pp)->next) {
+				cl = *pp;
+				if (cl->qdisc->q.qlen)
+					qfq_deactivate_class(q, cl, pp);
+			}
+		}
+	}
+
+	for (i = 0; i < q->clhash.hashsize; i++) {
+		hlist_for_each_entry(cl, n, &q->clhash.hash[i], common.hnode)
+			qdisc_reset(cl->qdisc);
+	}
+	sch->q.qlen = 0;
+}
+
+static void qfq_destroy_qdisc(struct Qdisc *sch)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_class *cl;
+	struct hlist_node *n, *next;
+	unsigned int i;
+
+	tcf_destroy_chain(&q->filter_list);
+
+	for (i = 0; i < q->clhash.hashsize; i++) {
+		hlist_for_each_entry_safe(cl, n, next, &q->clhash.hash[i],
+					  common.hnode)
+			qfq_destroy_class(sch, cl);
+	}
+	qdisc_class_hash_destroy(&q->clhash);
+}
+
+static const struct Qdisc_class_ops qfq_class_ops = {
+	.change		= qfq_change_class,
+	.delete		= qfq_delete_class,
+	.get		= qfq_get_class,
+	.put		= qfq_put_class,
+	.tcf_chain	= qfq_tcf_chain,
+	.bind_tcf	= qfq_bind_tcf,
+	.unbind_tcf	= qfq_unbind_tcf,
+	.graft		= qfq_graft_class,
+	.leaf		= qfq_class_leaf,
+	.qlen_notify	= qfq_qlen_notify,
+	.dump		= qfq_dump_class,
+	.dump_stats	= qfq_dump_class_stats,
+	.walk		= qfq_walk,
+};
+
+static struct Qdisc_ops qfq_qdisc_ops __read_mostly = {
+	.cl_ops		= &qfq_class_ops,
+	.id		= "qfq",
+	.priv_size	= sizeof(struct qfq_sched),
+	.enqueue	= qfq_enqueue,
+	.dequeue	= qfq_dequeue,
+	.peek		= qdisc_peek_dequeued,
+	.drop		= qfq_drop,
+	.init		= qfq_init_qdisc,
+	.reset		= qfq_reset_qdisc,
+	.destroy	= qfq_destroy_qdisc,
+	.owner		= THIS_MODULE,
+};
+
+static int __init qfq_init(void)
+{
+	return register_qdisc(&qfq_qdisc_ops);
+}
+
+static void __exit qfq_exit(void)
+{
+	unregister_qdisc(&qfq_qdisc_ops);
+}
+
+module_init(qfq_init);
+module_exit(qfq_exit);
+MODULE_LICENSE("GPL");
