1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * net/sched/sch_qfq.c Quick Fair Queueing Plus Scheduler.
4 *
5 * Copyright (c) 2009 Fabio Checconi, Luigi Rizzo, and Paolo Valente.
6 * Copyright (c) 2012 Paolo Valente.
7 */
8
9#include <linux/module.h>
10#include <linux/init.h>
11#include <linux/bitops.h>
12#include <linux/errno.h>
13#include <linux/netdevice.h>
14#include <linux/pkt_sched.h>
15#include <net/sch_generic.h>
16#include <net/pkt_sched.h>
17#include <net/pkt_cls.h>
18
19
20/* Quick Fair Queueing Plus
21 ========================
22
23 Sources:
24
25 [1] Paolo Valente,
26 "Reducing the Execution Time of Fair-Queueing Schedulers."
27 http://algo.ing.unimo.it/people/paolo/agg-sched/agg-sched.pdf
28
29 Sources for QFQ:
30
31 [2] Fabio Checconi, Luigi Rizzo, and Paolo Valente: "QFQ: Efficient
32 Packet Scheduling with Tight Bandwidth Distribution Guarantees."
33
34 See also:
35 http://retis.sssup.it/~fabio/linux/qfq/
36 */
37
38/*
39
40 QFQ+ divides classes into aggregates of at most MAX_AGG_CLASSES
41 classes. Each aggregate is timestamped with a virtual start time S
42 and a virtual finish time F, and scheduled according to its
43 timestamps. S and F are computed as a function of a system virtual
44 time function V. The classes within each aggregate are instead
45 scheduled with DRR.
46
47 To speed up operations, QFQ+ divides also aggregates into a limited
48 number of groups. Which group a class belongs to depends on the
49 ratio between the maximum packet length for the class and the weight
50 of the class. Groups have their own S and F. In the end, QFQ+
51 schedules groups, then aggregates within groups, then classes within
52 aggregates. See [1] and [2] for a full description.
53
54 Virtual time computations.
55
56 S, F and V are all computed in fixed point arithmetic with
57 FRAC_BITS decimal bits.
58
59 QFQ_MAX_INDEX is the maximum index allowed for a group. We need
60 one bit per index.
61 QFQ_MAX_WSHIFT is the maximum power of two supported as a weight.
62
63 The layout of the bits is as below:
64
65 [ MTU_SHIFT ][ FRAC_BITS ]
66 [ MAX_INDEX ][ MIN_SLOT_SHIFT ]
67 ^.__grp->index = 0
68 *.__grp->slot_shift
69
70 where MIN_SLOT_SHIFT is derived by difference from the others.
71
72 The max group index corresponds to Lmax/w_min, where
73 Lmax=1<<MTU_SHIFT, w_min = 1 .
74 From this, and knowing how many groups (MAX_INDEX) we want,
75 we can derive the shift corresponding to each group.
76
77 Because we often need to compute
78 F = S + len/w_i and V = V + len/wsum
79 instead of storing w_i store the value
80 inv_w = (1<<FRAC_BITS)/w_i
81 so we can do F = S + len * inv_w * wsum.
82 We use W_TOT in the formulas so we can easily move between
83 static and adaptive weight sum.
84
85 The per-scheduler-instance data contain all the data structures
86 for the scheduler: bitmaps and bucket lists.
87
88 */
89
90/*
91 * Maximum number of consecutive slots occupied by backlogged classes
92 * inside a group.
93 */
94#define QFQ_MAX_SLOTS 32
95
96/*
97 * Shifts used for aggregate<->group mapping. We allow class weights that are
98 * in the range [1, 2^MAX_WSHIFT], and we try to map each aggregate i to the
99 * group with the smallest index that can support the L_i / r_i configured
100 * for the classes in the aggregate.
101 *
102 * grp->index is the index of the group; and grp->slot_shift
103 * is the shift for the corresponding (scaled) sigma_i.
104 */
105#define QFQ_MAX_INDEX 24
106#define QFQ_MAX_WSHIFT 10
107
108#define QFQ_MAX_WEIGHT (1<<QFQ_MAX_WSHIFT) /* see qfq_slot_insert */
109#define QFQ_MAX_WSUM (64*QFQ_MAX_WEIGHT)
110
111#define FRAC_BITS 30 /* fixed point arithmetic */
112#define ONE_FP (1UL << FRAC_BITS)
113
114#define QFQ_MTU_SHIFT 16 /* to support TSO/GSO */
115#define QFQ_MIN_LMAX 512 /* see qfq_slot_insert */
116#define QFQ_MAX_LMAX (1UL << QFQ_MTU_SHIFT)
117
118#define QFQ_MAX_AGG_CLASSES 8 /* max num classes per aggregate allowed */
119
120/*
121 * Possible group states. These values are used as indexes for the bitmaps
122 * array of struct qfq_queue.
123 */
124enum qfq_state { ER, IR, EB, IB, QFQ_MAX_STATE };
125
126struct qfq_group;
127
128struct qfq_aggregate;
129
130struct qfq_class {
131 struct Qdisc_class_common common;
132
133 struct gnet_stats_basic_sync bstats;
134 struct gnet_stats_queue qstats;
135 struct net_rate_estimator __rcu *rate_est;
136 struct Qdisc *qdisc;
137 struct list_head alist; /* Link for active-classes list. */
138 struct qfq_aggregate *agg; /* Parent aggregate. */
139 int deficit; /* DRR deficit counter. */
140};
141
142struct qfq_aggregate {
143 struct hlist_node next; /* Link for the slot list. */
144 u64 S, F; /* flow timestamps (exact) */
145
146 /* group we belong to. In principle we would need the index,
147 * which is log_2(lmax/weight), but we never reference it
148 * directly, only the group.
149 */
150 struct qfq_group *grp;
151
152 /* these are copied from the flowset. */
153 u32 class_weight; /* Weight of each class in this aggregate. */
154 /* Max pkt size for the classes in this aggregate, DRR quantum. */
155 int lmax;
156
157 u32 inv_w; /* ONE_FP/(sum of weights of classes in aggr.). */
158 u32 budgetmax; /* Max budget for this aggregate. */
159 u32 initial_budget, budget; /* Initial and current budget. */
160
161 int num_classes; /* Number of classes in this aggr. */
162 struct list_head active; /* DRR queue of active classes. */
163
164 struct hlist_node nonfull_next; /* See nonfull_aggs in qfq_sched. */
165};
166
167struct qfq_group {
168 u64 S, F; /* group timestamps (approx). */
169 unsigned int slot_shift; /* Slot shift. */
170 unsigned int index; /* Group index. */
171 unsigned int front; /* Index of the front slot. */
172 unsigned long full_slots; /* non-empty slots */
173
174 /* Array of RR lists of active aggregates. */
175 struct hlist_head slots[QFQ_MAX_SLOTS];
176};
177
178struct qfq_sched {
179 struct tcf_proto __rcu *filter_list;
180 struct tcf_block *block;
181 struct Qdisc_class_hash clhash;
182
183 u64 oldV, V; /* Precise virtual times. */
184 struct qfq_aggregate *in_serv_agg; /* Aggregate being served. */
185 u32 wsum; /* weight sum */
186 u32 iwsum; /* inverse weight sum */
187
188 unsigned long bitmaps[QFQ_MAX_STATE]; /* Group bitmaps. */
189 struct qfq_group groups[QFQ_MAX_INDEX + 1]; /* The groups. */
190 u32 min_slot_shift; /* Index of the group-0 bit in the bitmaps. */
191
192 u32 max_agg_classes; /* Max number of classes per aggr. */
193 struct hlist_head nonfull_aggs; /* Aggs with room for more classes. */
194};
195
196/*
197 * Possible reasons why the timestamps of an aggregate are updated
198 * enqueue: the aggregate switches from idle to active and must scheduled
199 * for service
200 * requeue: the aggregate finishes its budget, so it stops being served and
201 * must be rescheduled for service
202 */
203enum update_reason {enqueue, requeue};
204
205static struct qfq_class *qfq_find_class(struct Qdisc *sch, u32 classid)
206{
207 struct qfq_sched *q = qdisc_priv(sch);
208 struct Qdisc_class_common *clc;
209
210 clc = qdisc_class_find(hash: &q->clhash, id: classid);
211 if (clc == NULL)
212 return NULL;
213 return container_of(clc, struct qfq_class, common);
214}
215
216static const struct netlink_range_validation lmax_range = {
217 .min = QFQ_MIN_LMAX,
218 .max = QFQ_MAX_LMAX,
219};
220
221static const struct nla_policy qfq_policy[TCA_QFQ_MAX + 1] = {
222 [TCA_QFQ_WEIGHT] = NLA_POLICY_RANGE(NLA_U32, 1, QFQ_MAX_WEIGHT),
223 [TCA_QFQ_LMAX] = NLA_POLICY_FULL_RANGE(NLA_U32, &lmax_range),
224};
225
226/*
227 * Calculate a flow index, given its weight and maximum packet length.
228 * index = log_2(maxlen/weight) but we need to apply the scaling.
229 * This is used only once at flow creation.
230 */
231static int qfq_calc_index(u32 inv_w, unsigned int maxlen, u32 min_slot_shift)
232{
233 u64 slot_size = (u64)maxlen * inv_w;
234 unsigned long size_map;
235 int index = 0;
236
237 size_map = slot_size >> min_slot_shift;
238 if (!size_map)
239 goto out;
240
241 index = __fls(word: size_map) + 1; /* basically a log_2 */
242 index -= !(slot_size - (1ULL << (index + min_slot_shift - 1)));
243
244 if (index < 0)
245 index = 0;
246out:
247 pr_debug("qfq calc_index: W = %lu, L = %u, I = %d\n",
248 (unsigned long) ONE_FP/inv_w, maxlen, index);
249
250 return index;
251}
252
253static void qfq_deactivate_agg(struct qfq_sched *, struct qfq_aggregate *);
254static void qfq_activate_agg(struct qfq_sched *, struct qfq_aggregate *,
255 enum update_reason);
256
257static void qfq_init_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
258 u32 lmax, u32 weight)
259{
260 INIT_LIST_HEAD(list: &agg->active);
261 hlist_add_head(n: &agg->nonfull_next, h: &q->nonfull_aggs);
262
263 agg->lmax = lmax;
264 agg->class_weight = weight;
265}
266
267static struct qfq_aggregate *qfq_find_agg(struct qfq_sched *q,
268 u32 lmax, u32 weight)
269{
270 struct qfq_aggregate *agg;
271
272 hlist_for_each_entry(agg, &q->nonfull_aggs, nonfull_next)
273 if (agg->lmax == lmax && agg->class_weight == weight)
274 return agg;
275
276 return NULL;
277}
278
279
280/* Update aggregate as a function of the new number of classes. */
281static void qfq_update_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
282 int new_num_classes)
283{
284 u32 new_agg_weight;
285
286 if (new_num_classes == q->max_agg_classes)
287 hlist_del_init(n: &agg->nonfull_next);
288
289 if (agg->num_classes > new_num_classes &&
290 new_num_classes == q->max_agg_classes - 1) /* agg no more full */
291 hlist_add_head(n: &agg->nonfull_next, h: &q->nonfull_aggs);
292
293 /* The next assignment may let
294 * agg->initial_budget > agg->budgetmax
295 * hold, we will take it into account in charge_actual_service().
296 */
297 agg->budgetmax = new_num_classes * agg->lmax;
298 new_agg_weight = agg->class_weight * new_num_classes;
299 agg->inv_w = ONE_FP/new_agg_weight;
300
301 if (agg->grp == NULL) {
302 int i = qfq_calc_index(inv_w: agg->inv_w, maxlen: agg->budgetmax,
303 min_slot_shift: q->min_slot_shift);
304 agg->grp = &q->groups[i];
305 }
306
307 q->wsum +=
308 (int) agg->class_weight * (new_num_classes - agg->num_classes);
309 q->iwsum = ONE_FP / q->wsum;
310
311 agg->num_classes = new_num_classes;
312}
313
314/* Add class to aggregate. */
315static void qfq_add_to_agg(struct qfq_sched *q,
316 struct qfq_aggregate *agg,
317 struct qfq_class *cl)
318{
319 cl->agg = agg;
320
321 qfq_update_agg(q, agg, new_num_classes: agg->num_classes+1);
322 if (cl->qdisc->q.qlen > 0) { /* adding an active class */
323 list_add_tail(new: &cl->alist, head: &agg->active);
324 if (list_first_entry(&agg->active, struct qfq_class, alist) ==
325 cl && q->in_serv_agg != agg) /* agg was inactive */
326 qfq_activate_agg(q, agg, enqueue); /* schedule agg */
327 }
328}
329
330static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *);
331
332static void qfq_destroy_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
333{
334 hlist_del_init(n: &agg->nonfull_next);
335 q->wsum -= agg->class_weight;
336 if (q->wsum != 0)
337 q->iwsum = ONE_FP / q->wsum;
338
339 if (q->in_serv_agg == agg)
340 q->in_serv_agg = qfq_choose_next_agg(q);
341 kfree(objp: agg);
342}
343
344/* Deschedule class from within its parent aggregate. */
345static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl)
346{
347 struct qfq_aggregate *agg = cl->agg;
348
349
350 list_del(entry: &cl->alist); /* remove from RR queue of the aggregate */
351 if (list_empty(head: &agg->active)) /* agg is now inactive */
352 qfq_deactivate_agg(q, agg);
353}
354
355/* Remove class from its parent aggregate. */
356static void qfq_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl)
357{
358 struct qfq_aggregate *agg = cl->agg;
359
360 cl->agg = NULL;
361 if (agg->num_classes == 1) { /* agg being emptied, destroy it */
362 qfq_destroy_agg(q, agg);
363 return;
364 }
365 qfq_update_agg(q, agg, new_num_classes: agg->num_classes-1);
366}
367
368/* Deschedule class and remove it from its parent aggregate. */
369static void qfq_deact_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl)
370{
371 if (cl->qdisc->q.qlen > 0) /* class is active */
372 qfq_deactivate_class(q, cl);
373
374 qfq_rm_from_agg(q, cl);
375}
376
377/* Move class to a new aggregate, matching the new class weight and/or lmax */
378static int qfq_change_agg(struct Qdisc *sch, struct qfq_class *cl, u32 weight,
379 u32 lmax)
380{
381 struct qfq_sched *q = qdisc_priv(sch);
382 struct qfq_aggregate *new_agg;
383
384 /* 'lmax' can range from [QFQ_MIN_LMAX, pktlen + stab overhead] */
385 if (lmax > QFQ_MAX_LMAX)
386 return -EINVAL;
387
388 new_agg = qfq_find_agg(q, lmax, weight);
389 if (new_agg == NULL) { /* create new aggregate */
390 new_agg = kzalloc(size: sizeof(*new_agg), GFP_ATOMIC);
391 if (new_agg == NULL)
392 return -ENOBUFS;
393 qfq_init_agg(q, agg: new_agg, lmax, weight);
394 }
395 qfq_deact_rm_from_agg(q, cl);
396 qfq_add_to_agg(q, agg: new_agg, cl);
397
398 return 0;
399}
400
401static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
402 struct nlattr **tca, unsigned long *arg,
403 struct netlink_ext_ack *extack)
404{
405 struct qfq_sched *q = qdisc_priv(sch);
406 struct qfq_class *cl = (struct qfq_class *)*arg;
407 bool existing = false;
408 struct nlattr *tb[TCA_QFQ_MAX + 1];
409 struct qfq_aggregate *new_agg = NULL;
410 u32 weight, lmax, inv_w;
411 int err;
412 int delta_w;
413
414 if (NL_REQ_ATTR_CHECK(extack, NULL, tca, TCA_OPTIONS)) {
415 NL_SET_ERR_MSG_MOD(extack, "missing options");
416 return -EINVAL;
417 }
418
419 err = nla_parse_nested_deprecated(tb, TCA_QFQ_MAX, nla: tca[TCA_OPTIONS],
420 policy: qfq_policy, extack);
421 if (err < 0)
422 return err;
423
424 if (tb[TCA_QFQ_WEIGHT])
425 weight = nla_get_u32(nla: tb[TCA_QFQ_WEIGHT]);
426 else
427 weight = 1;
428
429 if (tb[TCA_QFQ_LMAX]) {
430 lmax = nla_get_u32(nla: tb[TCA_QFQ_LMAX]);
431 } else {
432 /* MTU size is user controlled */
433 lmax = psched_mtu(dev: qdisc_dev(qdisc: sch));
434 if (lmax < QFQ_MIN_LMAX || lmax > QFQ_MAX_LMAX) {
435 NL_SET_ERR_MSG_MOD(extack,
436 "MTU size out of bounds for qfq");
437 return -EINVAL;
438 }
439 }
440
441 inv_w = ONE_FP / weight;
442 weight = ONE_FP / inv_w;
443
444 if (cl != NULL &&
445 lmax == cl->agg->lmax &&
446 weight == cl->agg->class_weight)
447 return 0; /* nothing to change */
448
449 delta_w = weight - (cl ? cl->agg->class_weight : 0);
450
451 if (q->wsum + delta_w > QFQ_MAX_WSUM) {
452 NL_SET_ERR_MSG_FMT_MOD(extack,
453 "total weight out of range (%d + %u)\n",
454 delta_w, q->wsum);
455 return -EINVAL;
456 }
457
458 if (cl != NULL) { /* modify existing class */
459 if (tca[TCA_RATE]) {
460 err = gen_replace_estimator(bstats: &cl->bstats, NULL,
461 ptr: &cl->rate_est,
462 NULL,
463 running: true,
464 opt: tca[TCA_RATE]);
465 if (err)
466 return err;
467 }
468 existing = true;
469 goto set_change_agg;
470 }
471
472 /* create and init new class */
473 cl = kzalloc(size: sizeof(struct qfq_class), GFP_KERNEL);
474 if (cl == NULL)
475 return -ENOBUFS;
476
477 gnet_stats_basic_sync_init(b: &cl->bstats);
478 cl->common.classid = classid;
479 cl->deficit = lmax;
480
481 cl->qdisc = qdisc_create_dflt(dev_queue: sch->dev_queue, ops: &pfifo_qdisc_ops,
482 parentid: classid, NULL);
483 if (cl->qdisc == NULL)
484 cl->qdisc = &noop_qdisc;
485
486 if (tca[TCA_RATE]) {
487 err = gen_new_estimator(bstats: &cl->bstats, NULL,
488 rate_est: &cl->rate_est,
489 NULL,
490 running: true,
491 opt: tca[TCA_RATE]);
492 if (err)
493 goto destroy_class;
494 }
495
496 if (cl->qdisc != &noop_qdisc)
497 qdisc_hash_add(q: cl->qdisc, invisible: true);
498
499set_change_agg:
500 sch_tree_lock(q: sch);
501 new_agg = qfq_find_agg(q, lmax, weight);
502 if (new_agg == NULL) { /* create new aggregate */
503 sch_tree_unlock(q: sch);
504 new_agg = kzalloc(size: sizeof(*new_agg), GFP_KERNEL);
505 if (new_agg == NULL) {
506 err = -ENOBUFS;
507 gen_kill_estimator(ptr: &cl->rate_est);
508 goto destroy_class;
509 }
510 sch_tree_lock(q: sch);
511 qfq_init_agg(q, agg: new_agg, lmax, weight);
512 }
513 if (existing)
514 qfq_deact_rm_from_agg(q, cl);
515 else
516 qdisc_class_hash_insert(&q->clhash, &cl->common);
517 qfq_add_to_agg(q, agg: new_agg, cl);
518 sch_tree_unlock(q: sch);
519 qdisc_class_hash_grow(sch, &q->clhash);
520
521 *arg = (unsigned long)cl;
522 return 0;
523
524destroy_class:
525 qdisc_put(qdisc: cl->qdisc);
526 kfree(objp: cl);
527 return err;
528}
529
530static void qfq_destroy_class(struct Qdisc *sch, struct qfq_class *cl)
531{
532 struct qfq_sched *q = qdisc_priv(sch);
533
534 qfq_rm_from_agg(q, cl);
535 gen_kill_estimator(ptr: &cl->rate_est);
536 qdisc_put(qdisc: cl->qdisc);
537 kfree(objp: cl);
538}
539
540static int qfq_delete_class(struct Qdisc *sch, unsigned long arg,
541 struct netlink_ext_ack *extack)
542{
543 struct qfq_sched *q = qdisc_priv(sch);
544 struct qfq_class *cl = (struct qfq_class *)arg;
545
546 if (qdisc_class_in_use(cl: &cl->common)) {
547 NL_SET_ERR_MSG_MOD(extack, "QFQ class in use");
548 return -EBUSY;
549 }
550
551 sch_tree_lock(q: sch);
552
553 qdisc_purge_queue(sch: cl->qdisc);
554 qdisc_class_hash_remove(&q->clhash, &cl->common);
555
556 sch_tree_unlock(q: sch);
557
558 qfq_destroy_class(sch, cl);
559 return 0;
560}
561
562static unsigned long qfq_search_class(struct Qdisc *sch, u32 classid)
563{
564 return (unsigned long)qfq_find_class(sch, classid);
565}
566
567static struct tcf_block *qfq_tcf_block(struct Qdisc *sch, unsigned long cl,
568 struct netlink_ext_ack *extack)
569{
570 struct qfq_sched *q = qdisc_priv(sch);
571
572 if (cl)
573 return NULL;
574
575 return q->block;
576}
577
578static unsigned long qfq_bind_tcf(struct Qdisc *sch, unsigned long parent,
579 u32 classid)
580{
581 struct qfq_class *cl = qfq_find_class(sch, classid);
582
583 if (cl)
584 qdisc_class_get(cl: &cl->common);
585
586 return (unsigned long)cl;
587}
588
589static void qfq_unbind_tcf(struct Qdisc *sch, unsigned long arg)
590{
591 struct qfq_class *cl = (struct qfq_class *)arg;
592
593 qdisc_class_put(cl: &cl->common);
594}
595
596static int qfq_graft_class(struct Qdisc *sch, unsigned long arg,
597 struct Qdisc *new, struct Qdisc **old,
598 struct netlink_ext_ack *extack)
599{
600 struct qfq_class *cl = (struct qfq_class *)arg;
601
602 if (new == NULL) {
603 new = qdisc_create_dflt(dev_queue: sch->dev_queue, ops: &pfifo_qdisc_ops,
604 parentid: cl->common.classid, NULL);
605 if (new == NULL)
606 new = &noop_qdisc;
607 }
608
609 *old = qdisc_replace(sch, new, pold: &cl->qdisc);
610 return 0;
611}
612
613static struct Qdisc *qfq_class_leaf(struct Qdisc *sch, unsigned long arg)
614{
615 struct qfq_class *cl = (struct qfq_class *)arg;
616
617 return cl->qdisc;
618}
619
620static int qfq_dump_class(struct Qdisc *sch, unsigned long arg,
621 struct sk_buff *skb, struct tcmsg *tcm)
622{
623 struct qfq_class *cl = (struct qfq_class *)arg;
624 struct nlattr *nest;
625
626 tcm->tcm_parent = TC_H_ROOT;
627 tcm->tcm_handle = cl->common.classid;
628 tcm->tcm_info = cl->qdisc->handle;
629
630 nest = nla_nest_start_noflag(skb, attrtype: TCA_OPTIONS);
631 if (nest == NULL)
632 goto nla_put_failure;
633 if (nla_put_u32(skb, attrtype: TCA_QFQ_WEIGHT, value: cl->agg->class_weight) ||
634 nla_put_u32(skb, attrtype: TCA_QFQ_LMAX, value: cl->agg->lmax))
635 goto nla_put_failure;
636 return nla_nest_end(skb, start: nest);
637
638nla_put_failure:
639 nla_nest_cancel(skb, start: nest);
640 return -EMSGSIZE;
641}
642
643static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg,
644 struct gnet_dump *d)
645{
646 struct qfq_class *cl = (struct qfq_class *)arg;
647 struct tc_qfq_stats xstats;
648
649 memset(&xstats, 0, sizeof(xstats));
650
651 xstats.weight = cl->agg->class_weight;
652 xstats.lmax = cl->agg->lmax;
653
654 if (gnet_stats_copy_basic(d, NULL, b: &cl->bstats, running: true) < 0 ||
655 gnet_stats_copy_rate_est(d, ptr: &cl->rate_est) < 0 ||
656 qdisc_qstats_copy(d, sch: cl->qdisc) < 0)
657 return -1;
658
659 return gnet_stats_copy_app(d, st: &xstats, len: sizeof(xstats));
660}
661
662static void qfq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
663{
664 struct qfq_sched *q = qdisc_priv(sch);
665 struct qfq_class *cl;
666 unsigned int i;
667
668 if (arg->stop)
669 return;
670
671 for (i = 0; i < q->clhash.hashsize; i++) {
672 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
673 if (!tc_qdisc_stats_dump(sch, cl: (unsigned long)cl, arg))
674 return;
675 }
676 }
677}
678
679static struct qfq_class *qfq_classify(struct sk_buff *skb, struct Qdisc *sch,
680 int *qerr)
681{
682 struct qfq_sched *q = qdisc_priv(sch);
683 struct qfq_class *cl;
684 struct tcf_result res;
685 struct tcf_proto *fl;
686 int result;
687
688 if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
689 pr_debug("qfq_classify: found %d\n", skb->priority);
690 cl = qfq_find_class(sch, classid: skb->priority);
691 if (cl != NULL)
692 return cl;
693 }
694
695 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
696 fl = rcu_dereference_bh(q->filter_list);
697 result = tcf_classify(skb, NULL, tp: fl, res: &res, compat_mode: false);
698 if (result >= 0) {
699#ifdef CONFIG_NET_CLS_ACT
700 switch (result) {
701 case TC_ACT_QUEUED:
702 case TC_ACT_STOLEN:
703 case TC_ACT_TRAP:
704 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
705 fallthrough;
706 case TC_ACT_SHOT:
707 return NULL;
708 }
709#endif
710 cl = (struct qfq_class *)res.class;
711 if (cl == NULL)
712 cl = qfq_find_class(sch, classid: res.classid);
713 return cl;
714 }
715
716 return NULL;
717}
718
719/* Generic comparison function, handling wraparound. */
720static inline int qfq_gt(u64 a, u64 b)
721{
722 return (s64)(a - b) > 0;
723}
724
725/* Round a precise timestamp to its slotted value. */
726static inline u64 qfq_round_down(u64 ts, unsigned int shift)
727{
728 return ts & ~((1ULL << shift) - 1);
729}
730
731/* return the pointer to the group with lowest index in the bitmap */
732static inline struct qfq_group *qfq_ffs(struct qfq_sched *q,
733 unsigned long bitmap)
734{
735 int index = __ffs(bitmap);
736 return &q->groups[index];
737}
738/* Calculate a mask to mimic what would be ffs_from(). */
739static inline unsigned long mask_from(unsigned long bitmap, int from)
740{
741 return bitmap & ~((1UL << from) - 1);
742}
743
744/*
745 * The state computation relies on ER=0, IR=1, EB=2, IB=3
746 * First compute eligibility comparing grp->S, q->V,
747 * then check if someone is blocking us and possibly add EB
748 */
749static int qfq_calc_state(struct qfq_sched *q, const struct qfq_group *grp)
750{
751 /* if S > V we are not eligible */
752 unsigned int state = qfq_gt(a: grp->S, b: q->V);
753 unsigned long mask = mask_from(bitmap: q->bitmaps[ER], from: grp->index);
754 struct qfq_group *next;
755
756 if (mask) {
757 next = qfq_ffs(q, bitmap: mask);
758 if (qfq_gt(a: grp->F, b: next->F))
759 state |= EB;
760 }
761
762 return state;
763}
764
765
766/*
767 * In principle
768 * q->bitmaps[dst] |= q->bitmaps[src] & mask;
769 * q->bitmaps[src] &= ~mask;
770 * but we should make sure that src != dst
771 */
772static inline void qfq_move_groups(struct qfq_sched *q, unsigned long mask,
773 int src, int dst)
774{
775 q->bitmaps[dst] |= q->bitmaps[src] & mask;
776 q->bitmaps[src] &= ~mask;
777}
778
779static void qfq_unblock_groups(struct qfq_sched *q, int index, u64 old_F)
780{
781 unsigned long mask = mask_from(bitmap: q->bitmaps[ER], from: index + 1);
782 struct qfq_group *next;
783
784 if (mask) {
785 next = qfq_ffs(q, bitmap: mask);
786 if (!qfq_gt(a: next->F, b: old_F))
787 return;
788 }
789
790 mask = (1UL << index) - 1;
791 qfq_move_groups(q, mask, src: EB, dst: ER);
792 qfq_move_groups(q, mask, src: IB, dst: IR);
793}
794
795/*
796 * perhaps
797 *
798 old_V ^= q->V;
799 old_V >>= q->min_slot_shift;
800 if (old_V) {
801 ...
802 }
803 *
804 */
805static void qfq_make_eligible(struct qfq_sched *q)
806{
807 unsigned long vslot = q->V >> q->min_slot_shift;
808 unsigned long old_vslot = q->oldV >> q->min_slot_shift;
809
810 if (vslot != old_vslot) {
811 unsigned long mask;
812 int last_flip_pos = fls(x: vslot ^ old_vslot);
813
814 if (last_flip_pos > 31) /* higher than the number of groups */
815 mask = ~0UL; /* make all groups eligible */
816 else
817 mask = (1UL << last_flip_pos) - 1;
818
819 qfq_move_groups(q, mask, src: IR, dst: ER);
820 qfq_move_groups(q, mask, src: IB, dst: EB);
821 }
822}
823
824/*
825 * The index of the slot in which the input aggregate agg is to be
826 * inserted must not be higher than QFQ_MAX_SLOTS-2. There is a '-2'
827 * and not a '-1' because the start time of the group may be moved
828 * backward by one slot after the aggregate has been inserted, and
829 * this would cause non-empty slots to be right-shifted by one
830 * position.
831 *
832 * QFQ+ fully satisfies this bound to the slot index if the parameters
833 * of the classes are not changed dynamically, and if QFQ+ never
834 * happens to postpone the service of agg unjustly, i.e., it never
835 * happens that the aggregate becomes backlogged and eligible, or just
836 * eligible, while an aggregate with a higher approximated finish time
837 * is being served. In particular, in this case QFQ+ guarantees that
838 * the timestamps of agg are low enough that the slot index is never
839 * higher than 2. Unfortunately, QFQ+ cannot provide the same
840 * guarantee if it happens to unjustly postpone the service of agg, or
841 * if the parameters of some class are changed.
842 *
843 * As for the first event, i.e., an out-of-order service, the
844 * upper bound to the slot index guaranteed by QFQ+ grows to
845 * 2 +
846 * QFQ_MAX_AGG_CLASSES * ((1<<QFQ_MTU_SHIFT)/QFQ_MIN_LMAX) *
847 * (current_max_weight/current_wsum) <= 2 + 8 * 128 * 1.
848 *
849 * The following function deals with this problem by backward-shifting
850 * the timestamps of agg, if needed, so as to guarantee that the slot
851 * index is never higher than QFQ_MAX_SLOTS-2. This backward-shift may
852 * cause the service of other aggregates to be postponed, yet the
853 * worst-case guarantees of these aggregates are not violated. In
854 * fact, in case of no out-of-order service, the timestamps of agg
855 * would have been even lower than they are after the backward shift,
856 * because QFQ+ would have guaranteed a maximum value equal to 2 for
857 * the slot index, and 2 < QFQ_MAX_SLOTS-2. Hence the aggregates whose
858 * service is postponed because of the backward-shift would have
859 * however waited for the service of agg before being served.
860 *
861 * The other event that may cause the slot index to be higher than 2
862 * for agg is a recent change of the parameters of some class. If the
863 * weight of a class is increased or the lmax (max_pkt_size) of the
864 * class is decreased, then a new aggregate with smaller slot size
865 * than the original parent aggregate of the class may happen to be
866 * activated. The activation of this aggregate should be properly
867 * delayed to when the service of the class has finished in the ideal
868 * system tracked by QFQ+. If the activation of the aggregate is not
869 * delayed to this reference time instant, then this aggregate may be
870 * unjustly served before other aggregates waiting for service. This
871 * may cause the above bound to the slot index to be violated for some
872 * of these unlucky aggregates.
873 *
874 * Instead of delaying the activation of the new aggregate, which is
875 * quite complex, the above-discussed capping of the slot index is
876 * used to handle also the consequences of a change of the parameters
877 * of a class.
878 */
879static void qfq_slot_insert(struct qfq_group *grp, struct qfq_aggregate *agg,
880 u64 roundedS)
881{
882 u64 slot = (roundedS - grp->S) >> grp->slot_shift;
883 unsigned int i; /* slot index in the bucket list */
884
885 if (unlikely(slot > QFQ_MAX_SLOTS - 2)) {
886 u64 deltaS = roundedS - grp->S -
887 ((u64)(QFQ_MAX_SLOTS - 2)<<grp->slot_shift);
888 agg->S -= deltaS;
889 agg->F -= deltaS;
890 slot = QFQ_MAX_SLOTS - 2;
891 }
892
893 i = (grp->front + slot) % QFQ_MAX_SLOTS;
894
895 hlist_add_head(n: &agg->next, h: &grp->slots[i]);
896 __set_bit(slot, &grp->full_slots);
897}
898
899/* Maybe introduce hlist_first_entry?? */
900static struct qfq_aggregate *qfq_slot_head(struct qfq_group *grp)
901{
902 return hlist_entry(grp->slots[grp->front].first,
903 struct qfq_aggregate, next);
904}
905
906/*
907 * remove the entry from the slot
908 */
909static void qfq_front_slot_remove(struct qfq_group *grp)
910{
911 struct qfq_aggregate *agg = qfq_slot_head(grp);
912
913 BUG_ON(!agg);
914 hlist_del(n: &agg->next);
915 if (hlist_empty(h: &grp->slots[grp->front]))
916 __clear_bit(0, &grp->full_slots);
917}
918
919/*
920 * Returns the first aggregate in the first non-empty bucket of the
921 * group. As a side effect, adjusts the bucket list so the first
922 * non-empty bucket is at position 0 in full_slots.
923 */
924static struct qfq_aggregate *qfq_slot_scan(struct qfq_group *grp)
925{
926 unsigned int i;
927
928 pr_debug("qfq slot_scan: grp %u full %#lx\n",
929 grp->index, grp->full_slots);
930
931 if (grp->full_slots == 0)
932 return NULL;
933
934 i = __ffs(grp->full_slots); /* zero based */
935 if (i > 0) {
936 grp->front = (grp->front + i) % QFQ_MAX_SLOTS;
937 grp->full_slots >>= i;
938 }
939
940 return qfq_slot_head(grp);
941}
942
943/*
944 * adjust the bucket list. When the start time of a group decreases,
945 * we move the index down (modulo QFQ_MAX_SLOTS) so we don't need to
946 * move the objects. The mask of occupied slots must be shifted
947 * because we use ffs() to find the first non-empty slot.
948 * This covers decreases in the group's start time, but what about
949 * increases of the start time ?
950 * Here too we should make sure that i is less than 32
951 */
952static void qfq_slot_rotate(struct qfq_group *grp, u64 roundedS)
953{
954 unsigned int i = (grp->S - roundedS) >> grp->slot_shift;
955
956 grp->full_slots <<= i;
957 grp->front = (grp->front - i) % QFQ_MAX_SLOTS;
958}
959
960static void qfq_update_eligible(struct qfq_sched *q)
961{
962 struct qfq_group *grp;
963 unsigned long ineligible;
964
965 ineligible = q->bitmaps[IR] | q->bitmaps[IB];
966 if (ineligible) {
967 if (!q->bitmaps[ER]) {
968 grp = qfq_ffs(q, bitmap: ineligible);
969 if (qfq_gt(a: grp->S, b: q->V))
970 q->V = grp->S;
971 }
972 qfq_make_eligible(q);
973 }
974}
975
976/* Dequeue head packet of the head class in the DRR queue of the aggregate. */
977static struct sk_buff *agg_dequeue(struct qfq_aggregate *agg,
978 struct qfq_class *cl, unsigned int len)
979{
980 struct sk_buff *skb = qdisc_dequeue_peeked(sch: cl->qdisc);
981
982 if (!skb)
983 return NULL;
984
985 cl->deficit -= (int) len;
986
987 if (cl->qdisc->q.qlen == 0) /* no more packets, remove from list */
988 list_del(entry: &cl->alist);
989 else if (cl->deficit < qdisc_pkt_len(skb: cl->qdisc->ops->peek(cl->qdisc))) {
990 cl->deficit += agg->lmax;
991 list_move_tail(list: &cl->alist, head: &agg->active);
992 }
993
994 return skb;
995}
996
997static inline struct sk_buff *qfq_peek_skb(struct qfq_aggregate *agg,
998 struct qfq_class **cl,
999 unsigned int *len)
1000{
1001 struct sk_buff *skb;
1002
1003 *cl = list_first_entry(&agg->active, struct qfq_class, alist);
1004 skb = (*cl)->qdisc->ops->peek((*cl)->qdisc);
1005 if (skb == NULL)
1006 qdisc_warn_nonwc(txt: "qfq_dequeue", qdisc: (*cl)->qdisc);
1007 else
1008 *len = qdisc_pkt_len(skb);
1009
1010 return skb;
1011}
1012
1013/* Update F according to the actual service received by the aggregate. */
1014static inline void charge_actual_service(struct qfq_aggregate *agg)
1015{
1016 /* Compute the service received by the aggregate, taking into
1017 * account that, after decreasing the number of classes in
1018 * agg, it may happen that
1019 * agg->initial_budget - agg->budget > agg->bugdetmax
1020 */
1021 u32 service_received = min(agg->budgetmax,
1022 agg->initial_budget - agg->budget);
1023
1024 agg->F = agg->S + (u64)service_received * agg->inv_w;
1025}
1026
1027/* Assign a reasonable start time for a new aggregate in group i.
1028 * Admissible values for \hat(F) are multiples of \sigma_i
1029 * no greater than V+\sigma_i . Larger values mean that
1030 * we had a wraparound so we consider the timestamp to be stale.
1031 *
1032 * If F is not stale and F >= V then we set S = F.
1033 * Otherwise we should assign S = V, but this may violate
1034 * the ordering in EB (see [2]). So, if we have groups in ER,
1035 * set S to the F_j of the first group j which would be blocking us.
1036 * We are guaranteed not to move S backward because
1037 * otherwise our group i would still be blocked.
1038 */
1039static void qfq_update_start(struct qfq_sched *q, struct qfq_aggregate *agg)
1040{
1041 unsigned long mask;
1042 u64 limit, roundedF;
1043 int slot_shift = agg->grp->slot_shift;
1044
1045 roundedF = qfq_round_down(ts: agg->F, shift: slot_shift);
1046 limit = qfq_round_down(ts: q->V, shift: slot_shift) + (1ULL << slot_shift);
1047
1048 if (!qfq_gt(a: agg->F, b: q->V) || qfq_gt(a: roundedF, b: limit)) {
1049 /* timestamp was stale */
1050 mask = mask_from(bitmap: q->bitmaps[ER], from: agg->grp->index);
1051 if (mask) {
1052 struct qfq_group *next = qfq_ffs(q, bitmap: mask);
1053 if (qfq_gt(a: roundedF, b: next->F)) {
1054 if (qfq_gt(a: limit, b: next->F))
1055 agg->S = next->F;
1056 else /* preserve timestamp correctness */
1057 agg->S = limit;
1058 return;
1059 }
1060 }
1061 agg->S = q->V;
1062 } else /* timestamp is not stale */
1063 agg->S = agg->F;
1064}
1065
1066/* Update the timestamps of agg before scheduling/rescheduling it for
1067 * service. In particular, assign to agg->F its maximum possible
1068 * value, i.e., the virtual finish time with which the aggregate
1069 * should be labeled if it used all its budget once in service.
1070 */
1071static inline void
1072qfq_update_agg_ts(struct qfq_sched *q,
1073 struct qfq_aggregate *agg, enum update_reason reason)
1074{
1075 if (reason != requeue)
1076 qfq_update_start(q, agg);
1077 else /* just charge agg for the service received */
1078 agg->S = agg->F;
1079
1080 agg->F = agg->S + (u64)agg->budgetmax * agg->inv_w;
1081}
1082
1083static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg);
1084
1085static struct sk_buff *qfq_dequeue(struct Qdisc *sch)
1086{
1087 struct qfq_sched *q = qdisc_priv(sch);
1088 struct qfq_aggregate *in_serv_agg = q->in_serv_agg;
1089 struct qfq_class *cl;
1090 struct sk_buff *skb = NULL;
1091 /* next-packet len, 0 means no more active classes in in-service agg */
1092 unsigned int len = 0;
1093
1094 if (in_serv_agg == NULL)
1095 return NULL;
1096
1097 if (!list_empty(head: &in_serv_agg->active))
1098 skb = qfq_peek_skb(agg: in_serv_agg, cl: &cl, len: &len);
1099
1100 /*
1101 * If there are no active classes in the in-service aggregate,
1102 * or if the aggregate has not enough budget to serve its next
1103 * class, then choose the next aggregate to serve.
1104 */
1105 if (len == 0 || in_serv_agg->budget < len) {
1106 charge_actual_service(agg: in_serv_agg);
1107
1108 /* recharge the budget of the aggregate */
1109 in_serv_agg->initial_budget = in_serv_agg->budget =
1110 in_serv_agg->budgetmax;
1111
1112 if (!list_empty(head: &in_serv_agg->active)) {
1113 /*
1114 * Still active: reschedule for
1115 * service. Possible optimization: if no other
1116 * aggregate is active, then there is no point
1117 * in rescheduling this aggregate, and we can
1118 * just keep it as the in-service one. This
1119 * should be however a corner case, and to
1120 * handle it, we would need to maintain an
1121 * extra num_active_aggs field.
1122 */
1123 qfq_update_agg_ts(q, agg: in_serv_agg, reason: requeue);
1124 qfq_schedule_agg(q, agg: in_serv_agg);
1125 } else if (sch->q.qlen == 0) { /* no aggregate to serve */
1126 q->in_serv_agg = NULL;
1127 return NULL;
1128 }
1129
1130 /*
1131 * If we get here, there are other aggregates queued:
1132 * choose the new aggregate to serve.
1133 */
1134 in_serv_agg = q->in_serv_agg = qfq_choose_next_agg(q);
1135 skb = qfq_peek_skb(agg: in_serv_agg, cl: &cl, len: &len);
1136 }
1137 if (!skb)
1138 return NULL;
1139
1140 sch->q.qlen--;
1141
1142 skb = agg_dequeue(agg: in_serv_agg, cl, len);
1143
1144 if (!skb) {
1145 sch->q.qlen++;
1146 return NULL;
1147 }
1148
1149 qdisc_qstats_backlog_dec(sch, skb);
1150 qdisc_bstats_update(sch, skb);
1151
1152 /* If lmax is lowered, through qfq_change_class, for a class
1153 * owning pending packets with larger size than the new value
1154 * of lmax, then the following condition may hold.
1155 */
1156 if (unlikely(in_serv_agg->budget < len))
1157 in_serv_agg->budget = 0;
1158 else
1159 in_serv_agg->budget -= len;
1160
1161 q->V += (u64)len * q->iwsum;
1162 pr_debug("qfq dequeue: len %u F %lld now %lld\n",
1163 len, (unsigned long long) in_serv_agg->F,
1164 (unsigned long long) q->V);
1165
1166 return skb;
1167}
1168
1169static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *q)
1170{
1171 struct qfq_group *grp;
1172 struct qfq_aggregate *agg, *new_front_agg;
1173 u64 old_F;
1174
1175 qfq_update_eligible(q);
1176 q->oldV = q->V;
1177
1178 if (!q->bitmaps[ER])
1179 return NULL;
1180
1181 grp = qfq_ffs(q, bitmap: q->bitmaps[ER]);
1182 old_F = grp->F;
1183
1184 agg = qfq_slot_head(grp);
1185
1186 /* agg starts to be served, remove it from schedule */
1187 qfq_front_slot_remove(grp);
1188
1189 new_front_agg = qfq_slot_scan(grp);
1190
1191 if (new_front_agg == NULL) /* group is now inactive, remove from ER */
1192 __clear_bit(grp->index, &q->bitmaps[ER]);
1193 else {
1194 u64 roundedS = qfq_round_down(ts: new_front_agg->S,
1195 shift: grp->slot_shift);
1196 unsigned int s;
1197
1198 if (grp->S == roundedS)
1199 return agg;
1200 grp->S = roundedS;
1201 grp->F = roundedS + (2ULL << grp->slot_shift);
1202 __clear_bit(grp->index, &q->bitmaps[ER]);
1203 s = qfq_calc_state(q, grp);
1204 __set_bit(grp->index, &q->bitmaps[s]);
1205 }
1206
1207 qfq_unblock_groups(q, index: grp->index, old_F);
1208
1209 return agg;
1210}
1211
1212static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
1213 struct sk_buff **to_free)
1214{
1215 unsigned int len = qdisc_pkt_len(skb), gso_segs;
1216 struct qfq_sched *q = qdisc_priv(sch);
1217 struct qfq_class *cl;
1218 struct qfq_aggregate *agg;
1219 int err = 0;
1220 bool first;
1221
1222 cl = qfq_classify(skb, sch, qerr: &err);
1223 if (cl == NULL) {
1224 if (err & __NET_XMIT_BYPASS)
1225 qdisc_qstats_drop(sch);
1226 __qdisc_drop(skb, to_free);
1227 return err;
1228 }
1229 pr_debug("qfq_enqueue: cl = %x\n", cl->common.classid);
1230
1231 if (unlikely(cl->agg->lmax < len)) {
1232 pr_debug("qfq: increasing maxpkt from %u to %u for class %u",
1233 cl->agg->lmax, len, cl->common.classid);
1234 err = qfq_change_agg(sch, cl, weight: cl->agg->class_weight, lmax: len);
1235 if (err) {
1236 cl->qstats.drops++;
1237 return qdisc_drop(skb, sch, to_free);
1238 }
1239 }
1240
1241 gso_segs = skb_is_gso(skb) ? skb_shinfo(skb)->gso_segs : 1;
1242 first = !cl->qdisc->q.qlen;
1243 err = qdisc_enqueue(skb, sch: cl->qdisc, to_free);
1244 if (unlikely(err != NET_XMIT_SUCCESS)) {
1245 pr_debug("qfq_enqueue: enqueue failed %d\n", err);
1246 if (net_xmit_drop_count(err)) {
1247 cl->qstats.drops++;
1248 qdisc_qstats_drop(sch);
1249 }
1250 return err;
1251 }
1252
1253 _bstats_update(bstats: &cl->bstats, bytes: len, packets: gso_segs);
1254 sch->qstats.backlog += len;
1255 ++sch->q.qlen;
1256
1257 agg = cl->agg;
1258 /* if the queue was not empty, then done here */
1259 if (!first) {
1260 if (unlikely(skb == cl->qdisc->ops->peek(cl->qdisc)) &&
1261 list_first_entry(&agg->active, struct qfq_class, alist)
1262 == cl && cl->deficit < len)
1263 list_move_tail(list: &cl->alist, head: &agg->active);
1264
1265 return err;
1266 }
1267
1268 /* schedule class for service within the aggregate */
1269 cl->deficit = agg->lmax;
1270 list_add_tail(new: &cl->alist, head: &agg->active);
1271
1272 if (list_first_entry(&agg->active, struct qfq_class, alist) != cl ||
1273 q->in_serv_agg == agg)
1274 return err; /* non-empty or in service, nothing else to do */
1275
1276 qfq_activate_agg(q, agg, enqueue);
1277
1278 return err;
1279}
1280
1281/*
1282 * Schedule aggregate according to its timestamps.
1283 */
1284static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
1285{
1286 struct qfq_group *grp = agg->grp;
1287 u64 roundedS;
1288 int s;
1289
1290 roundedS = qfq_round_down(ts: agg->S, shift: grp->slot_shift);
1291
1292 /*
1293 * Insert agg in the correct bucket.
1294 * If agg->S >= grp->S we don't need to adjust the
1295 * bucket list and simply go to the insertion phase.
1296 * Otherwise grp->S is decreasing, we must make room
1297 * in the bucket list, and also recompute the group state.
1298 * Finally, if there were no flows in this group and nobody
1299 * was in ER make sure to adjust V.
1300 */
1301 if (grp->full_slots) {
1302 if (!qfq_gt(a: grp->S, b: agg->S))
1303 goto skip_update;
1304
1305 /* create a slot for this agg->S */
1306 qfq_slot_rotate(grp, roundedS);
1307 /* group was surely ineligible, remove */
1308 __clear_bit(grp->index, &q->bitmaps[IR]);
1309 __clear_bit(grp->index, &q->bitmaps[IB]);
1310 } else if (!q->bitmaps[ER] && qfq_gt(a: roundedS, b: q->V) &&
1311 q->in_serv_agg == NULL)
1312 q->V = roundedS;
1313
1314 grp->S = roundedS;
1315 grp->F = roundedS + (2ULL << grp->slot_shift);
1316 s = qfq_calc_state(q, grp);
1317 __set_bit(grp->index, &q->bitmaps[s]);
1318
1319 pr_debug("qfq enqueue: new state %d %#lx S %lld F %lld V %lld\n",
1320 s, q->bitmaps[s],
1321 (unsigned long long) agg->S,
1322 (unsigned long long) agg->F,
1323 (unsigned long long) q->V);
1324
1325skip_update:
1326 qfq_slot_insert(grp, agg, roundedS);
1327}
1328
1329
1330/* Update agg ts and schedule agg for service */
1331static void qfq_activate_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
1332 enum update_reason reason)
1333{
1334 agg->initial_budget = agg->budget = agg->budgetmax; /* recharge budg. */
1335
1336 qfq_update_agg_ts(q, agg, reason);
1337 if (q->in_serv_agg == NULL) { /* no aggr. in service or scheduled */
1338 q->in_serv_agg = agg; /* start serving this aggregate */
1339 /* update V: to be in service, agg must be eligible */
1340 q->oldV = q->V = agg->S;
1341 } else if (agg != q->in_serv_agg)
1342 qfq_schedule_agg(q, agg);
1343}
1344
1345static void qfq_slot_remove(struct qfq_sched *q, struct qfq_group *grp,
1346 struct qfq_aggregate *agg)
1347{
1348 unsigned int i, offset;
1349 u64 roundedS;
1350
1351 roundedS = qfq_round_down(ts: agg->S, shift: grp->slot_shift);
1352 offset = (roundedS - grp->S) >> grp->slot_shift;
1353
1354 i = (grp->front + offset) % QFQ_MAX_SLOTS;
1355
1356 hlist_del(n: &agg->next);
1357 if (hlist_empty(h: &grp->slots[i]))
1358 __clear_bit(offset, &grp->full_slots);
1359}
1360
1361/*
1362 * Called to forcibly deschedule an aggregate. If the aggregate is
1363 * not in the front bucket, or if the latter has other aggregates in
1364 * the front bucket, we can simply remove the aggregate with no other
1365 * side effects.
1366 * Otherwise we must propagate the event up.
1367 */
1368static void qfq_deactivate_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
1369{
1370 struct qfq_group *grp = agg->grp;
1371 unsigned long mask;
1372 u64 roundedS;
1373 int s;
1374
1375 if (agg == q->in_serv_agg) {
1376 charge_actual_service(agg);
1377 q->in_serv_agg = qfq_choose_next_agg(q);
1378 return;
1379 }
1380
1381 agg->F = agg->S;
1382 qfq_slot_remove(q, grp, agg);
1383
1384 if (!grp->full_slots) {
1385 __clear_bit(grp->index, &q->bitmaps[IR]);
1386 __clear_bit(grp->index, &q->bitmaps[EB]);
1387 __clear_bit(grp->index, &q->bitmaps[IB]);
1388
1389 if (test_bit(grp->index, &q->bitmaps[ER]) &&
1390 !(q->bitmaps[ER] & ~((1UL << grp->index) - 1))) {
1391 mask = q->bitmaps[ER] & ((1UL << grp->index) - 1);
1392 if (mask)
1393 mask = ~((1UL << __fls(word: mask)) - 1);
1394 else
1395 mask = ~0UL;
1396 qfq_move_groups(q, mask, src: EB, dst: ER);
1397 qfq_move_groups(q, mask, src: IB, dst: IR);
1398 }
1399 __clear_bit(grp->index, &q->bitmaps[ER]);
1400 } else if (hlist_empty(h: &grp->slots[grp->front])) {
1401 agg = qfq_slot_scan(grp);
1402 roundedS = qfq_round_down(ts: agg->S, shift: grp->slot_shift);
1403 if (grp->S != roundedS) {
1404 __clear_bit(grp->index, &q->bitmaps[ER]);
1405 __clear_bit(grp->index, &q->bitmaps[IR]);
1406 __clear_bit(grp->index, &q->bitmaps[EB]);
1407 __clear_bit(grp->index, &q->bitmaps[IB]);
1408 grp->S = roundedS;
1409 grp->F = roundedS + (2ULL << grp->slot_shift);
1410 s = qfq_calc_state(q, grp);
1411 __set_bit(grp->index, &q->bitmaps[s]);
1412 }
1413 }
1414}
1415
1416static void qfq_qlen_notify(struct Qdisc *sch, unsigned long arg)
1417{
1418 struct qfq_sched *q = qdisc_priv(sch);
1419 struct qfq_class *cl = (struct qfq_class *)arg;
1420
1421 qfq_deactivate_class(q, cl);
1422}
1423
1424static int qfq_init_qdisc(struct Qdisc *sch, struct nlattr *opt,
1425 struct netlink_ext_ack *extack)
1426{
1427 struct qfq_sched *q = qdisc_priv(sch);
1428 struct qfq_group *grp;
1429 int i, j, err;
1430 u32 max_cl_shift, maxbudg_shift, max_classes;
1431
1432 err = tcf_block_get(p_block: &q->block, p_filter_chain: &q->filter_list, q: sch, extack);
1433 if (err)
1434 return err;
1435
1436 err = qdisc_class_hash_init(&q->clhash);
1437 if (err < 0)
1438 return err;
1439
1440 max_classes = min_t(u64, (u64)qdisc_dev(sch)->tx_queue_len + 1,
1441 QFQ_MAX_AGG_CLASSES);
1442 /* max_cl_shift = floor(log_2(max_classes)) */
1443 max_cl_shift = __fls(word: max_classes);
1444 q->max_agg_classes = 1<<max_cl_shift;
1445
1446 /* maxbudg_shift = log2(max_len * max_classes_per_agg) */
1447 maxbudg_shift = QFQ_MTU_SHIFT + max_cl_shift;
1448 q->min_slot_shift = FRAC_BITS + maxbudg_shift - QFQ_MAX_INDEX;
1449
1450 for (i = 0; i <= QFQ_MAX_INDEX; i++) {
1451 grp = &q->groups[i];
1452 grp->index = i;
1453 grp->slot_shift = q->min_slot_shift + i;
1454 for (j = 0; j < QFQ_MAX_SLOTS; j++)
1455 INIT_HLIST_HEAD(&grp->slots[j]);
1456 }
1457
1458 INIT_HLIST_HEAD(&q->nonfull_aggs);
1459
1460 return 0;
1461}
1462
1463static void qfq_reset_qdisc(struct Qdisc *sch)
1464{
1465 struct qfq_sched *q = qdisc_priv(sch);
1466 struct qfq_class *cl;
1467 unsigned int i;
1468
1469 for (i = 0; i < q->clhash.hashsize; i++) {
1470 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
1471 if (cl->qdisc->q.qlen > 0)
1472 qfq_deactivate_class(q, cl);
1473
1474 qdisc_reset(qdisc: cl->qdisc);
1475 }
1476 }
1477}
1478
1479static void qfq_destroy_qdisc(struct Qdisc *sch)
1480{
1481 struct qfq_sched *q = qdisc_priv(sch);
1482 struct qfq_class *cl;
1483 struct hlist_node *next;
1484 unsigned int i;
1485
1486 tcf_block_put(block: q->block);
1487
1488 for (i = 0; i < q->clhash.hashsize; i++) {
1489 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],
1490 common.hnode) {
1491 qfq_destroy_class(sch, cl);
1492 }
1493 }
1494 qdisc_class_hash_destroy(&q->clhash);
1495}
1496
1497static const struct Qdisc_class_ops qfq_class_ops = {
1498 .change = qfq_change_class,
1499 .delete = qfq_delete_class,
1500 .find = qfq_search_class,
1501 .tcf_block = qfq_tcf_block,
1502 .bind_tcf = qfq_bind_tcf,
1503 .unbind_tcf = qfq_unbind_tcf,
1504 .graft = qfq_graft_class,
1505 .leaf = qfq_class_leaf,
1506 .qlen_notify = qfq_qlen_notify,
1507 .dump = qfq_dump_class,
1508 .dump_stats = qfq_dump_class_stats,
1509 .walk = qfq_walk,
1510};
1511
1512static struct Qdisc_ops qfq_qdisc_ops __read_mostly = {
1513 .cl_ops = &qfq_class_ops,
1514 .id = "qfq",
1515 .priv_size = sizeof(struct qfq_sched),
1516 .enqueue = qfq_enqueue,
1517 .dequeue = qfq_dequeue,
1518 .peek = qdisc_peek_dequeued,
1519 .init = qfq_init_qdisc,
1520 .reset = qfq_reset_qdisc,
1521 .destroy = qfq_destroy_qdisc,
1522 .owner = THIS_MODULE,
1523};
1524
1525static int __init qfq_init(void)
1526{
1527 return register_qdisc(qops: &qfq_qdisc_ops);
1528}
1529
1530static void __exit qfq_exit(void)
1531{
1532 unregister_qdisc(qops: &qfq_qdisc_ops);
1533}
1534
1535module_init(qfq_init);
1536module_exit(qfq_exit);
1537MODULE_LICENSE("GPL");
1538

source code of linux/net/sched/sch_qfq.c