Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1532 insertions, 0 deletions

diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c
new file mode 100644
index 000000000..20dc1851d
--- /dev/null
+++ b/net/sched/sch_qfq.c
@@ -0,0 +1,1532 @@
+/*
+ * net/sched/sch_qfq.c         Quick Fair Queueing Plus Scheduler.
+ *
+ * Copyright (c) 2009 Fabio Checconi, Luigi Rizzo, and Paolo Valente.
+ * Copyright (c) 2012 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 Plus
+    ========================
+
+    Sources:
+
+    [1] Paolo Valente,
+    "Reducing the Execution Time of Fair-Queueing Schedulers."
+    http://algo.ing.unimo.it/people/paolo/agg-sched/agg-sched.pdf
+
+    Sources for QFQ:
+
+    [2] Fabio Checconi, Luigi Rizzo, and Paolo Valente: "QFQ: Efficient
+    Packet Scheduling with Tight Bandwidth Distribution Guarantees."
+
+    See also:
+    http://retis.sssup.it/~fabio/linux/qfq/
+ */
+
+/*
+
+  QFQ+ divides classes into aggregates of at most MAX_AGG_CLASSES
+  classes. Each aggregate is timestamped with a virtual start time S
+  and a virtual finish time F, and scheduled according to its
+  timestamps. S and F are computed as a function of a system virtual
+  time function V. The classes within each aggregate are instead
+  scheduled with DRR.
+
+  To speed up operations, QFQ+ divides also aggregates into a limited
+  number of groups. Which group a class belongs to depends on the
+  ratio between the maximum packet length for the class and the weight
+  of the class. Groups have their own S and F. In the end, QFQ+
+  schedules groups, then aggregates within groups, then classes within
+  aggregates. See [1] and [2] for a full description.
+
+  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 aggregate<->group mapping.  We allow class weights that are
+ * in the range [1, 2^MAX_WSHIFT], and we try to map each aggregate i to the
+ * group with the smallest index that can support the L_i / r_i configured
+ * for the classes in the aggregate.
+ *
+ * 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		24
+#define QFQ_MAX_WSHIFT		10
+
+#define	QFQ_MAX_WEIGHT		(1<<QFQ_MAX_WSHIFT) /* see qfq_slot_insert */
+#define QFQ_MAX_WSUM		(64*QFQ_MAX_WEIGHT)
+
+#define FRAC_BITS		30	/* fixed point arithmetic */
+#define ONE_FP			(1UL << FRAC_BITS)
+
+#define QFQ_MTU_SHIFT		16	/* to support TSO/GSO */
+#define QFQ_MIN_LMAX		512	/* see qfq_slot_insert */
+
+#define QFQ_MAX_AGG_CLASSES	8 /* max num classes per aggregate allowed */
+
+/*
+ * 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_aggregate;
+
+struct qfq_class {
+	struct Qdisc_class_common common;
+
+	unsigned int filter_cnt;
+
+	struct gnet_stats_basic_packed bstats;
+	struct gnet_stats_queue qstats;
+	struct net_rate_estimator __rcu *rate_est;
+	struct Qdisc *qdisc;
+	struct list_head alist;		/* Link for active-classes list. */
+	struct qfq_aggregate *agg;	/* Parent aggregate. */
+	int deficit;			/* DRR deficit counter. */
+};
+
+struct qfq_aggregate {
+	struct hlist_node 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	class_weight; /* Weight of each class in this aggregate. */
+	/* Max pkt size for the classes in this aggregate, DRR quantum. */
+	int	lmax;
+
+	u32	inv_w;	    /* ONE_FP/(sum of weights of classes in aggr.). */
+	u32	budgetmax;  /* Max budget for this aggregate. */
+	u32	initial_budget, budget;     /* Initial and current budget. */
+
+	int		  num_classes;	/* Number of classes in this aggr. */
+	struct list_head  active;	/* DRR queue of active classes. */
+
+	struct hlist_node nonfull_next;	/* See nonfull_aggs in qfq_sched. */
+};
+
+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 aggregates. */
+	struct hlist_head slots[QFQ_MAX_SLOTS];
+};
+
+struct qfq_sched {
+	struct tcf_proto __rcu *filter_list;
+	struct tcf_block	*block;
+	struct Qdisc_class_hash clhash;
+
+	u64			oldV, V;	/* Precise virtual times. */
+	struct qfq_aggregate	*in_serv_agg;   /* Aggregate being served. */
+	u32			wsum;		/* weight sum */
+	u32			iwsum;		/* inverse weight sum */
+
+	unsigned long bitmaps[QFQ_MAX_STATE];	    /* Group bitmaps. */
+	struct qfq_group groups[QFQ_MAX_INDEX + 1]; /* The groups. */
+	u32 min_slot_shift;	/* Index of the group-0 bit in the bitmaps. */
+
+	u32 max_agg_classes;		/* Max number of classes per aggr. */
+	struct hlist_head nonfull_aggs; /* Aggs with room for more classes. */
+};
+
+/*
+ * Possible reasons why the timestamps of an aggregate are updated
+ * enqueue: the aggregate switches from idle to active and must scheduled
+ *	    for service
+ * requeue: the aggregate finishes its budget, so it stops being served and
+ *	    must be rescheduled for service
+ */
+enum update_reason {enqueue, requeue};
+
+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;
+	unsigned int backlog = cl->qdisc->qstats.backlog;
+
+	qdisc_reset(cl->qdisc);
+	qdisc_tree_reduce_backlog(cl->qdisc, len, backlog);
+}
+
+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, u32 min_slot_shift)
+{
+	u64 slot_size = (u64)maxlen * inv_w;
+	unsigned long size_map;
+	int index = 0;
+
+	size_map = slot_size >> min_slot_shift;
+	if (!size_map)
+		goto out;
+
+	index = __fls(size_map) + 1;	/* basically a log_2 */
+	index -= !(slot_size - (1ULL << (index + 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 void qfq_deactivate_agg(struct qfq_sched *, struct qfq_aggregate *);
+static void qfq_activate_agg(struct qfq_sched *, struct qfq_aggregate *,
+			     enum update_reason);
+
+static void qfq_init_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
+			 u32 lmax, u32 weight)
+{
+	INIT_LIST_HEAD(&agg->active);
+	hlist_add_head(&agg->nonfull_next, &q->nonfull_aggs);
+
+	agg->lmax = lmax;
+	agg->class_weight = weight;
+}
+
+static struct qfq_aggregate *qfq_find_agg(struct qfq_sched *q,
+					  u32 lmax, u32 weight)
+{
+	struct qfq_aggregate *agg;
+
+	hlist_for_each_entry(agg, &q->nonfull_aggs, nonfull_next)
+		if (agg->lmax == lmax && agg->class_weight == weight)
+			return agg;
+
+	return NULL;
+}
+
+
+/* Update aggregate as a function of the new number of classes. */
+static void qfq_update_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
+			   int new_num_classes)
+{
+	u32 new_agg_weight;
+
+	if (new_num_classes == q->max_agg_classes)
+		hlist_del_init(&agg->nonfull_next);
+
+	if (agg->num_classes > new_num_classes &&
+	    new_num_classes == q->max_agg_classes - 1) /* agg no more full */
+		hlist_add_head(&agg->nonfull_next, &q->nonfull_aggs);
+
+	/* The next assignment may let
+	 * agg->initial_budget > agg->budgetmax
+	 * hold, we will take it into account in charge_actual_service().
+	 */
+	agg->budgetmax = new_num_classes * agg->lmax;
+	new_agg_weight = agg->class_weight * new_num_classes;
+	agg->inv_w = ONE_FP/new_agg_weight;
+
+	if (agg->grp == NULL) {
+		int i = qfq_calc_index(agg->inv_w, agg->budgetmax,
+				       q->min_slot_shift);
+		agg->grp = &q->groups[i];
+	}
+
+	q->wsum +=
+		(int) agg->class_weight * (new_num_classes - agg->num_classes);
+	q->iwsum = ONE_FP / q->wsum;
+
+	agg->num_classes = new_num_classes;
+}
+
+/* Add class to aggregate. */
+static void qfq_add_to_agg(struct qfq_sched *q,
+			   struct qfq_aggregate *agg,
+			   struct qfq_class *cl)
+{
+	cl->agg = agg;
+
+	qfq_update_agg(q, agg, agg->num_classes+1);
+	if (cl->qdisc->q.qlen > 0) { /* adding an active class */
+		list_add_tail(&cl->alist, &agg->active);
+		if (list_first_entry(&agg->active, struct qfq_class, alist) ==
+		    cl && q->in_serv_agg != agg) /* agg was inactive */
+			qfq_activate_agg(q, agg, enqueue); /* schedule agg */
+	}
+}
+
+static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *);
+
+static void qfq_destroy_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
+{
+	hlist_del_init(&agg->nonfull_next);
+	q->wsum -= agg->class_weight;
+	if (q->wsum != 0)
+		q->iwsum = ONE_FP / q->wsum;
+
+	if (q->in_serv_agg == agg)
+		q->in_serv_agg = qfq_choose_next_agg(q);
+	kfree(agg);
+}
+
+/* Deschedule class from within its parent aggregate. */
+static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl)
+{
+	struct qfq_aggregate *agg = cl->agg;
+
+
+	list_del(&cl->alist); /* remove from RR queue of the aggregate */
+	if (list_empty(&agg->active)) /* agg is now inactive */
+		qfq_deactivate_agg(q, agg);
+}
+
+/* Remove class from its parent aggregate. */
+static void qfq_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl)
+{
+	struct qfq_aggregate *agg = cl->agg;
+
+	cl->agg = NULL;
+	if (agg->num_classes == 1) { /* agg being emptied, destroy it */
+		qfq_destroy_agg(q, agg);
+		return;
+	}
+	qfq_update_agg(q, agg, agg->num_classes-1);
+}
+
+/* Deschedule class and remove it from its parent aggregate. */
+static void qfq_deact_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl)
+{
+	if (cl->qdisc->q.qlen > 0) /* class is active */
+		qfq_deactivate_class(q, cl);
+
+	qfq_rm_from_agg(q, cl);
+}
+
+/* Move class to a new aggregate, matching the new class weight and/or lmax */
+static int qfq_change_agg(struct Qdisc *sch, struct qfq_class *cl, u32 weight,
+			   u32 lmax)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_aggregate *new_agg = qfq_find_agg(q, lmax, weight);
+
+	if (new_agg == NULL) { /* create new aggregate */
+		new_agg = kzalloc(sizeof(*new_agg), GFP_ATOMIC);
+		if (new_agg == NULL)
+			return -ENOBUFS;
+		qfq_init_agg(q, new_agg, lmax, weight);
+	}
+	qfq_deact_rm_from_agg(q, cl);
+	qfq_add_to_agg(q, new_agg, cl);
+
+	return 0;
+}
+
+static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
+			    struct nlattr **tca, unsigned long *arg,
+			    struct netlink_ext_ack *extack)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_class *cl = (struct qfq_class *)*arg;
+	bool existing = false;
+	struct nlattr *tb[TCA_QFQ_MAX + 1];
+	struct qfq_aggregate *new_agg = NULL;
+	u32 weight, lmax, inv_w;
+	int err;
+	int delta_w;
+
+	if (tca[TCA_OPTIONS] == NULL) {
+		pr_notice("qfq: no options\n");
+		return -EINVAL;
+	}
+
+	err = nla_parse_nested(tb, TCA_QFQ_MAX, tca[TCA_OPTIONS], qfq_policy,
+			       NULL);
+	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;
+
+	if (tb[TCA_QFQ_LMAX]) {
+		lmax = nla_get_u32(tb[TCA_QFQ_LMAX]);
+		if (lmax < QFQ_MIN_LMAX || lmax > (1UL << QFQ_MTU_SHIFT)) {
+			pr_notice("qfq: invalid max length %u\n", lmax);
+			return -EINVAL;
+		}
+	} else
+		lmax = psched_mtu(qdisc_dev(sch));
+
+	inv_w = ONE_FP / weight;
+	weight = ONE_FP / inv_w;
+
+	if (cl != NULL &&
+	    lmax == cl->agg->lmax &&
+	    weight == cl->agg->class_weight)
+		return 0; /* nothing to change */
+
+	delta_w = weight - (cl ? cl->agg->class_weight : 0);
+
+	if (q->wsum + delta_w > QFQ_MAX_WSUM) {
+		pr_notice("qfq: total weight out of range (%d + %u)\n",
+			  delta_w, q->wsum);
+		return -EINVAL;
+	}
+
+	if (cl != NULL) { /* modify existing class */
+		if (tca[TCA_RATE]) {
+			err = gen_replace_estimator(&cl->bstats, NULL,
+						    &cl->rate_est,
+						    NULL,
+						    qdisc_root_sleeping_running(sch),
+						    tca[TCA_RATE]);
+			if (err)
+				return err;
+		}
+		existing = true;
+		goto set_change_agg;
+	}
+
+	/* create and init new class */
+	cl = kzalloc(sizeof(struct qfq_class), GFP_KERNEL);
+	if (cl == NULL)
+		return -ENOBUFS;
+
+	cl->common.classid = classid;
+	cl->deficit = lmax;
+
+	cl->qdisc = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
+				      classid, NULL);
+	if (cl->qdisc == NULL)
+		cl->qdisc = &noop_qdisc;
+
+	if (tca[TCA_RATE]) {
+		err = gen_new_estimator(&cl->bstats, NULL,
+					&cl->rate_est,
+					NULL,
+					qdisc_root_sleeping_running(sch),
+					tca[TCA_RATE]);
+		if (err)
+			goto destroy_class;
+	}
+
+	if (cl->qdisc != &noop_qdisc)
+		qdisc_hash_add(cl->qdisc, true);
+
+set_change_agg:
+	sch_tree_lock(sch);
+	new_agg = qfq_find_agg(q, lmax, weight);
+	if (new_agg == NULL) { /* create new aggregate */
+		sch_tree_unlock(sch);
+		new_agg = kzalloc(sizeof(*new_agg), GFP_KERNEL);
+		if (new_agg == NULL) {
+			err = -ENOBUFS;
+			gen_kill_estimator(&cl->rate_est);
+			goto destroy_class;
+		}
+		sch_tree_lock(sch);
+		qfq_init_agg(q, new_agg, lmax, weight);
+	}
+	if (existing)
+		qfq_deact_rm_from_agg(q, cl);
+	else
+		qdisc_class_hash_insert(&q->clhash, &cl->common);
+	qfq_add_to_agg(q, new_agg, cl);
+	sch_tree_unlock(sch);
+	qdisc_class_hash_grow(sch, &q->clhash);
+
+	*arg = (unsigned long)cl;
+	return 0;
+
+destroy_class:
+	qdisc_put(cl->qdisc);
+	kfree(cl);
+	return err;
+}
+
+static void qfq_destroy_class(struct Qdisc *sch, struct qfq_class *cl)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+
+	qfq_rm_from_agg(q, cl);
+	gen_kill_estimator(&cl->rate_est);
+	qdisc_put(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);
+
+	sch_tree_unlock(sch);
+
+	qfq_destroy_class(sch, cl);
+	return 0;
+}
+
+static unsigned long qfq_search_class(struct Qdisc *sch, u32 classid)
+{
+	return (unsigned long)qfq_find_class(sch, classid);
+}
+
+static struct tcf_block *qfq_tcf_block(struct Qdisc *sch, unsigned long cl,
+				       struct netlink_ext_ack *extack)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+
+	if (cl)
+		return NULL;
+
+	return q->block;
+}
+
+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 netlink_ext_ack *extack)
+{
+	struct qfq_class *cl = (struct qfq_class *)arg;
+
+	if (new == NULL) {
+		new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
+					cl->common.classid, NULL);
+		if (new == NULL)
+			new = &noop_qdisc;
+	}
+
+	*old = qdisc_replace(sch, new, &cl->qdisc);
+	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;
+	if (nla_put_u32(skb, TCA_QFQ_WEIGHT, cl->agg->class_weight) ||
+	    nla_put_u32(skb, TCA_QFQ_LMAX, cl->agg->lmax))
+		goto nla_put_failure;
+	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 = cl->agg->class_weight;
+	xstats.lmax = cl->agg->lmax;
+
+	if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
+				  d, NULL, &cl->bstats) < 0 ||
+	    gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
+	    gnet_stats_copy_queue(d, NULL,
+				  &cl->qdisc->qstats, cl->qdisc->q.qlen) < 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;
+	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 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;
+	struct tcf_proto *fl;
+	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;
+	fl = rcu_dereference_bh(q->filter_list);
+	result = tcf_classify(skb, fl, &res, false);
+	if (result >= 0) {
+#ifdef CONFIG_NET_CLS_ACT
+		switch (result) {
+		case TC_ACT_QUEUED:
+		case TC_ACT_STOLEN:
+		case TC_ACT_TRAP:
+			*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
+			/* fall through */
+		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 >>= q->min_slot_shift;
+	if (old_V) {
+		...
+	}
+ *
+ */
+static void qfq_make_eligible(struct qfq_sched *q)
+{
+	unsigned long vslot = q->V >> q->min_slot_shift;
+	unsigned long old_vslot = q->oldV >> q->min_slot_shift;
+
+	if (vslot != old_vslot) {
+		unsigned long mask;
+		int last_flip_pos = fls(vslot ^ old_vslot);
+
+		if (last_flip_pos > 31) /* higher than the number of groups */
+			mask = ~0UL;    /* make all groups eligible */
+		else
+			mask = (1UL << last_flip_pos) - 1;
+
+		qfq_move_groups(q, mask, IR, ER);
+		qfq_move_groups(q, mask, IB, EB);
+	}
+}
+
+/*
+ * The index of the slot in which the input aggregate agg is to be
+ * inserted must not be higher than QFQ_MAX_SLOTS-2. There is a '-2'
+ * and not a '-1' because the start time of the group may be moved
+ * backward by one slot after the aggregate has been inserted, and
+ * this would cause non-empty slots to be right-shifted by one
+ * position.
+ *
+ * QFQ+ fully satisfies this bound to the slot index if the parameters
+ * of the classes are not changed dynamically, and if QFQ+ never
+ * happens to postpone the service of agg unjustly, i.e., it never
+ * happens that the aggregate becomes backlogged and eligible, or just
+ * eligible, while an aggregate with a higher approximated finish time
+ * is being served. In particular, in this case QFQ+ guarantees that
+ * the timestamps of agg are low enough that the slot index is never
+ * higher than 2. Unfortunately, QFQ+ cannot provide the same
+ * guarantee if it happens to unjustly postpone the service of agg, or
+ * if the parameters of some class are changed.
+ *
+ * As for the first event, i.e., an out-of-order service, the
+ * upper bound to the slot index guaranteed by QFQ+ grows to
+ * 2 +
+ * QFQ_MAX_AGG_CLASSES * ((1<<QFQ_MTU_SHIFT)/QFQ_MIN_LMAX) *
+ * (current_max_weight/current_wsum) <= 2 + 8 * 128 * 1.
+ *
+ * The following function deals with this problem by backward-shifting
+ * the timestamps of agg, if needed, so as to guarantee that the slot
+ * index is never higher than QFQ_MAX_SLOTS-2. This backward-shift may
+ * cause the service of other aggregates to be postponed, yet the
+ * worst-case guarantees of these aggregates are not violated.  In
+ * fact, in case of no out-of-order service, the timestamps of agg
+ * would have been even lower than they are after the backward shift,
+ * because QFQ+ would have guaranteed a maximum value equal to 2 for
+ * the slot index, and 2 < QFQ_MAX_SLOTS-2. Hence the aggregates whose
+ * service is postponed because of the backward-shift would have
+ * however waited for the service of agg before being served.
+ *
+ * The other event that may cause the slot index to be higher than 2
+ * for agg is a recent change of the parameters of some class. If the
+ * weight of a class is increased or the lmax (max_pkt_size) of the
+ * class is decreased, then a new aggregate with smaller slot size
+ * than the original parent aggregate of the class may happen to be
+ * activated. The activation of this aggregate should be properly
+ * delayed to when the service of the class has finished in the ideal
+ * system tracked by QFQ+. If the activation of the aggregate is not
+ * delayed to this reference time instant, then this aggregate may be
+ * unjustly served before other aggregates waiting for service. This
+ * may cause the above bound to the slot index to be violated for some
+ * of these unlucky aggregates.
+ *
+ * Instead of delaying the activation of the new aggregate, which is
+ * quite complex, the above-discussed capping of the slot index is
+ * used to handle also the consequences of a change of the parameters
+ * of a class.
+ */
+static void qfq_slot_insert(struct qfq_group *grp, struct qfq_aggregate *agg,
+			    u64 roundedS)
+{
+	u64 slot = (roundedS - grp->S) >> grp->slot_shift;
+	unsigned int i; /* slot index in the bucket list */
+
+	if (unlikely(slot > QFQ_MAX_SLOTS - 2)) {
+		u64 deltaS = roundedS - grp->S -
+			((u64)(QFQ_MAX_SLOTS - 2)<<grp->slot_shift);
+		agg->S -= deltaS;
+		agg->F -= deltaS;
+		slot = QFQ_MAX_SLOTS - 2;
+	}
+
+	i = (grp->front + slot) % QFQ_MAX_SLOTS;
+
+	hlist_add_head(&agg->next, &grp->slots[i]);
+	__set_bit(slot, &grp->full_slots);
+}
+
+/* Maybe introduce hlist_first_entry?? */
+static struct qfq_aggregate *qfq_slot_head(struct qfq_group *grp)
+{
+	return hlist_entry(grp->slots[grp->front].first,
+			   struct qfq_aggregate, next);
+}
+
+/*
+ * remove the entry from the slot
+ */
+static void qfq_front_slot_remove(struct qfq_group *grp)
+{
+	struct qfq_aggregate *agg = qfq_slot_head(grp);
+
+	BUG_ON(!agg);
+	hlist_del(&agg->next);
+	if (hlist_empty(&grp->slots[grp->front]))
+		__clear_bit(0, &grp->full_slots);
+}
+
+/*
+ * Returns the first aggregate in the first non-empty bucket of the
+ * group. As a side effect, adjusts the bucket list so the first
+ * non-empty bucket is at position 0 in full_slots.
+ */
+static struct qfq_aggregate *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 qfq_slot_head(grp);
+}
+
+/*
+ * 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)
+{
+	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);
+	}
+}
+
+/* Dequeue head packet of the head class in the DRR queue of the aggregate. */
+static void agg_dequeue(struct qfq_aggregate *agg,
+			struct qfq_class *cl, unsigned int len)
+{
+	qdisc_dequeue_peeked(cl->qdisc);
+
+	cl->deficit -= (int) len;
+
+	if (cl->qdisc->q.qlen == 0) /* no more packets, remove from list */
+		list_del(&cl->alist);
+	else if (cl->deficit < qdisc_pkt_len(cl->qdisc->ops->peek(cl->qdisc))) {
+		cl->deficit += agg->lmax;
+		list_move_tail(&cl->alist, &agg->active);
+	}
+}
+
+static inline struct sk_buff *qfq_peek_skb(struct qfq_aggregate *agg,
+					   struct qfq_class **cl,
+					   unsigned int *len)
+{
+	struct sk_buff *skb;
+
+	*cl = list_first_entry(&agg->active, struct qfq_class, alist);
+	skb = (*cl)->qdisc->ops->peek((*cl)->qdisc);
+	if (skb == NULL)
+		WARN_ONCE(1, "qfq_dequeue: non-workconserving leaf\n");
+	else
+		*len = qdisc_pkt_len(skb);
+
+	return skb;
+}
+
+/* Update F according to the actual service received by the aggregate. */
+static inline void charge_actual_service(struct qfq_aggregate *agg)
+{
+	/* Compute the service received by the aggregate, taking into
+	 * account that, after decreasing the number of classes in
+	 * agg, it may happen that
+	 * agg->initial_budget - agg->budget > agg->bugdetmax
+	 */
+	u32 service_received = min(agg->budgetmax,
+				   agg->initial_budget - agg->budget);
+
+	agg->F = agg->S + (u64)service_received * agg->inv_w;
+}
+
+/* Assign a reasonable start time for a new aggregate 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 EB (see [2]). 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_aggregate *agg)
+{
+	unsigned long mask;
+	u64 limit, roundedF;
+	int slot_shift = agg->grp->slot_shift;
+
+	roundedF = qfq_round_down(agg->F, slot_shift);
+	limit = qfq_round_down(q->V, slot_shift) + (1ULL << slot_shift);
+
+	if (!qfq_gt(agg->F, q->V) || qfq_gt(roundedF, limit)) {
+		/* timestamp was stale */
+		mask = mask_from(q->bitmaps[ER], agg->grp->index);
+		if (mask) {
+			struct qfq_group *next = qfq_ffs(q, mask);
+			if (qfq_gt(roundedF, next->F)) {
+				if (qfq_gt(limit, next->F))
+					agg->S = next->F;
+				else /* preserve timestamp correctness */
+					agg->S = limit;
+				return;
+			}
+		}
+		agg->S = q->V;
+	} else  /* timestamp is not stale */
+		agg->S = agg->F;
+}
+
+/* Update the timestamps of agg before scheduling/rescheduling it for
+ * service.  In particular, assign to agg->F its maximum possible
+ * value, i.e., the virtual finish time with which the aggregate
+ * should be labeled if it used all its budget once in service.
+ */
+static inline void
+qfq_update_agg_ts(struct qfq_sched *q,
+		    struct qfq_aggregate *agg, enum update_reason reason)
+{
+	if (reason != requeue)
+		qfq_update_start(q, agg);
+	else /* just charge agg for the service received */
+		agg->S = agg->F;
+
+	agg->F = agg->S + (u64)agg->budgetmax * agg->inv_w;
+}
+
+static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg);
+
+static struct sk_buff *qfq_dequeue(struct Qdisc *sch)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_aggregate *in_serv_agg = q->in_serv_agg;
+	struct qfq_class *cl;
+	struct sk_buff *skb = NULL;
+	/* next-packet len, 0 means no more active classes in in-service agg */
+	unsigned int len = 0;
+
+	if (in_serv_agg == NULL)
+		return NULL;
+
+	if (!list_empty(&in_serv_agg->active))
+		skb = qfq_peek_skb(in_serv_agg, &cl, &len);
+
+	/*
+	 * If there are no active classes in the in-service aggregate,
+	 * or if the aggregate has not enough budget to serve its next
+	 * class, then choose the next aggregate to serve.
+	 */
+	if (len == 0 || in_serv_agg->budget < len) {
+		charge_actual_service(in_serv_agg);
+
+		/* recharge the budget of the aggregate */
+		in_serv_agg->initial_budget = in_serv_agg->budget =
+			in_serv_agg->budgetmax;
+
+		if (!list_empty(&in_serv_agg->active)) {
+			/*
+			 * Still active: reschedule for
+			 * service. Possible optimization: if no other
+			 * aggregate is active, then there is no point
+			 * in rescheduling this aggregate, and we can
+			 * just keep it as the in-service one. This
+			 * should be however a corner case, and to
+			 * handle it, we would need to maintain an
+			 * extra num_active_aggs field.
+			*/
+			qfq_update_agg_ts(q, in_serv_agg, requeue);
+			qfq_schedule_agg(q, in_serv_agg);
+		} else if (sch->q.qlen == 0) { /* no aggregate to serve */
+			q->in_serv_agg = NULL;
+			return NULL;
+		}
+
+		/*
+		 * If we get here, there are other aggregates queued:
+		 * choose the new aggregate to serve.
+		 */
+		in_serv_agg = q->in_serv_agg = qfq_choose_next_agg(q);
+		skb = qfq_peek_skb(in_serv_agg, &cl, &len);
+	}
+	if (!skb)
+		return NULL;
+
+	qdisc_qstats_backlog_dec(sch, skb);
+	sch->q.qlen--;
+	qdisc_bstats_update(sch, skb);
+
+	agg_dequeue(in_serv_agg, cl, len);
+	/* If lmax is lowered, through qfq_change_class, for a class
+	 * owning pending packets with larger size than the new value
+	 * of lmax, then the following condition may hold.
+	 */
+	if (unlikely(in_serv_agg->budget < len))
+		in_serv_agg->budget = 0;
+	else
+		in_serv_agg->budget -= len;
+
+	q->V += (u64)len * q->iwsum;
+	pr_debug("qfq dequeue: len %u F %lld now %lld\n",
+		 len, (unsigned long long) in_serv_agg->F,
+		 (unsigned long long) q->V);
+
+	return skb;
+}
+
+static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *q)
+{
+	struct qfq_group *grp;
+	struct qfq_aggregate *agg, *new_front_agg;
+	u64 old_F;
+
+	qfq_update_eligible(q);
+	q->oldV = q->V;
+
+	if (!q->bitmaps[ER])
+		return NULL;
+
+	grp = qfq_ffs(q, q->bitmaps[ER]);
+	old_F = grp->F;
+
+	agg = qfq_slot_head(grp);
+
+	/* agg starts to be served, remove it from schedule */
+	qfq_front_slot_remove(grp);
+
+	new_front_agg = qfq_slot_scan(grp);
+
+	if (new_front_agg == NULL) /* group is now inactive, remove from ER */
+		__clear_bit(grp->index, &q->bitmaps[ER]);
+	else {
+		u64 roundedS = qfq_round_down(new_front_agg->S,
+					      grp->slot_shift);
+		unsigned int s;
+
+		if (grp->S == roundedS)
+			return agg;
+		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);
+
+	return agg;
+}
+
+static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
+		       struct sk_buff **to_free)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_class *cl;
+	struct qfq_aggregate *agg;
+	int err = 0;
+
+	cl = qfq_classify(skb, sch, &err);
+	if (cl == NULL) {
+		if (err & __NET_XMIT_BYPASS)
+			qdisc_qstats_drop(sch);
+		__qdisc_drop(skb, to_free);
+		return err;
+	}
+	pr_debug("qfq_enqueue: cl = %x\n", cl->common.classid);
+
+	if (unlikely(cl->agg->lmax < qdisc_pkt_len(skb))) {
+		pr_debug("qfq: increasing maxpkt from %u to %u for class %u",
+			 cl->agg->lmax, qdisc_pkt_len(skb), cl->common.classid);
+		err = qfq_change_agg(sch, cl, cl->agg->class_weight,
+				     qdisc_pkt_len(skb));
+		if (err) {
+			cl->qstats.drops++;
+			return qdisc_drop(skb, sch, to_free);
+		}
+	}
+
+	err = qdisc_enqueue(skb, cl->qdisc, to_free);
+	if (unlikely(err != NET_XMIT_SUCCESS)) {
+		pr_debug("qfq_enqueue: enqueue failed %d\n", err);
+		if (net_xmit_drop_count(err)) {
+			cl->qstats.drops++;
+			qdisc_qstats_drop(sch);
+		}
+		return err;
+	}
+
+	bstats_update(&cl->bstats, skb);
+	qdisc_qstats_backlog_inc(sch, skb);
+	++sch->q.qlen;
+
+	agg = cl->agg;
+	/* if the queue was not empty, then done here */
+	if (cl->qdisc->q.qlen != 1) {
+		if (unlikely(skb == cl->qdisc->ops->peek(cl->qdisc)) &&
+		    list_first_entry(&agg->active, struct qfq_class, alist)
+		    == cl && cl->deficit < qdisc_pkt_len(skb))
+			list_move_tail(&cl->alist, &agg->active);
+
+		return err;
+	}
+
+	/* schedule class for service within the aggregate */
+	cl->deficit = agg->lmax;
+	list_add_tail(&cl->alist, &agg->active);
+
+	if (list_first_entry(&agg->active, struct qfq_class, alist) != cl ||
+	    q->in_serv_agg == agg)
+		return err; /* non-empty or in service, nothing else to do */
+
+	qfq_activate_agg(q, agg, enqueue);
+
+	return err;
+}
+
+/*
+ * Schedule aggregate according to its timestamps.
+ */
+static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
+{
+	struct qfq_group *grp = agg->grp;
+	u64 roundedS;
+	int s;
+
+	roundedS = qfq_round_down(agg->S, grp->slot_shift);
+
+	/*
+	 * Insert agg in the correct bucket.
+	 * If agg->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, agg->S))
+			goto skip_update;
+
+		/* create a slot for this agg->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->in_serv_agg == NULL)
+		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) agg->S,
+		 (unsigned long long) agg->F,
+		 (unsigned long long) q->V);
+
+skip_update:
+	qfq_slot_insert(grp, agg, roundedS);
+}
+
+
+/* Update agg ts and schedule agg for service */
+static void qfq_activate_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
+			     enum update_reason reason)
+{
+	agg->initial_budget = agg->budget = agg->budgetmax; /* recharge budg. */
+
+	qfq_update_agg_ts(q, agg, reason);
+	if (q->in_serv_agg == NULL) { /* no aggr. in service or scheduled */
+		q->in_serv_agg = agg; /* start serving this aggregate */
+		 /* update V: to be in service, agg must be eligible */
+		q->oldV = q->V = agg->S;
+	} else if (agg != q->in_serv_agg)
+		qfq_schedule_agg(q, agg);
+}
+
+static void qfq_slot_remove(struct qfq_sched *q, struct qfq_group *grp,
+			    struct qfq_aggregate *agg)
+{
+	unsigned int i, offset;
+	u64 roundedS;
+
+	roundedS = qfq_round_down(agg->S, grp->slot_shift);
+	offset = (roundedS - grp->S) >> grp->slot_shift;
+
+	i = (grp->front + offset) % QFQ_MAX_SLOTS;
+
+	hlist_del(&agg->next);
+	if (hlist_empty(&grp->slots[i]))
+		__clear_bit(offset, &grp->full_slots);
+}
+
+/*
+ * Called to forcibly deschedule an aggregate.  If the aggregate is
+ * not in the front bucket, or if the latter has other aggregates in
+ * the front bucket, we can simply remove the aggregate with no other
+ * side effects.
+ * Otherwise we must propagate the event up.
+ */
+static void qfq_deactivate_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
+{
+	struct qfq_group *grp = agg->grp;
+	unsigned long mask;
+	u64 roundedS;
+	int s;
+
+	if (agg == q->in_serv_agg) {
+		charge_actual_service(agg);
+		q->in_serv_agg = qfq_choose_next_agg(q);
+		return;
+	}
+
+	agg->F = agg->S;
+	qfq_slot_remove(q, grp, agg);
+
+	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 (hlist_empty(&grp->slots[grp->front])) {
+		agg = qfq_slot_scan(grp);
+		roundedS = qfq_round_down(agg->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]);
+		}
+	}
+}
+
+static void qfq_qlen_notify(struct Qdisc *sch, unsigned long arg)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_class *cl = (struct qfq_class *)arg;
+
+	qfq_deactivate_class(q, cl);
+}
+
+static int qfq_init_qdisc(struct Qdisc *sch, struct nlattr *opt,
+			  struct netlink_ext_ack *extack)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_group *grp;
+	int i, j, err;
+	u32 max_cl_shift, maxbudg_shift, max_classes;
+
+	err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
+	if (err)
+		return err;
+
+	err = qdisc_class_hash_init(&q->clhash);
+	if (err < 0)
+		return err;
+
+	max_classes = min_t(u64, (u64)qdisc_dev(sch)->tx_queue_len + 1,
+			    QFQ_MAX_AGG_CLASSES);
+	/* max_cl_shift = floor(log_2(max_classes)) */
+	max_cl_shift = __fls(max_classes);
+	q->max_agg_classes = 1<<max_cl_shift;
+
+	/* maxbudg_shift = log2(max_len * max_classes_per_agg) */
+	maxbudg_shift = QFQ_MTU_SHIFT + max_cl_shift;
+	q->min_slot_shift = FRAC_BITS + maxbudg_shift - QFQ_MAX_INDEX;
+
+	for (i = 0; i <= QFQ_MAX_INDEX; i++) {
+		grp = &q->groups[i];
+		grp->index = i;
+		grp->slot_shift = q->min_slot_shift + i;
+		for (j = 0; j < QFQ_MAX_SLOTS; j++)
+			INIT_HLIST_HEAD(&grp->slots[j]);
+	}
+
+	INIT_HLIST_HEAD(&q->nonfull_aggs);
+
+	return 0;
+}
+
+static void qfq_reset_qdisc(struct Qdisc *sch)
+{
+	struct qfq_sched *q = qdisc_priv(sch);
+	struct qfq_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->qdisc->q.qlen > 0)
+				qfq_deactivate_class(q, cl);
+
+			qdisc_reset(cl->qdisc);
+		}
+	}
+	sch->qstats.backlog = 0;
+	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 *next;
+	unsigned int i;
+
+	tcf_block_put(q->block);
+
+	for (i = 0; i < q->clhash.hashsize; i++) {
+		hlist_for_each_entry_safe(cl, 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,
+	.find		= qfq_search_class,
+	.tcf_block	= qfq_tcf_block,
+	.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,
+	.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");