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 */
124 enum qfq_state { ER, IR, EB, IB, QFQ_MAX_STATE };
125
126 struct qfq_group;
127
128 struct qfq_aggregate;
129
130 struct qfq_class {
131 struct Qdisc_class_common common;
132
133 unsigned int filter_cnt;
134
135 struct gnet_stats_basic_packed bstats;
136 struct gnet_stats_queue qstats;
137 struct net_rate_estimator __rcu *rate_est;
138 struct Qdisc *qdisc;
139 struct list_head alist; /* Link for active-classes list. */
140 struct qfq_aggregate *agg; /* Parent aggregate. */
141 int deficit; /* DRR deficit counter. */
142 };
143
144 struct qfq_aggregate {
145 struct hlist_node next; /* Link for the slot list. */
146 u64 S, F; /* flow timestamps (exact) */
147
148 /* group we belong to. In principle we would need the index,
149 * which is log_2(lmax/weight), but we never reference it
150 * directly, only the group.
151 */
152 struct qfq_group *grp;
153
154 /* these are copied from the flowset. */
155 u32 class_weight; /* Weight of each class in this aggregate. */
156 /* Max pkt size for the classes in this aggregate, DRR quantum. */
157 int lmax;
158
159 u32 inv_w; /* ONE_FP/(sum of weights of classes in aggr.). */
160 u32 budgetmax; /* Max budget for this aggregate. */
161 u32 initial_budget, budget; /* Initial and current budget. */
162
163 int num_classes; /* Number of classes in this aggr. */
164 struct list_head active; /* DRR queue of active classes. */
165
166 struct hlist_node nonfull_next; /* See nonfull_aggs in qfq_sched. */
167 };
168
169 struct qfq_group {
170 u64 S, F; /* group timestamps (approx). */
171 unsigned int slot_shift; /* Slot shift. */
172 unsigned int index; /* Group index. */
173 unsigned int front; /* Index of the front slot. */
174 unsigned long full_slots; /* non-empty slots */
175
176 /* Array of RR lists of active aggregates. */
177 struct hlist_head slots[QFQ_MAX_SLOTS];
178 };
179
180 struct qfq_sched {
181 struct tcf_proto __rcu *filter_list;
182 struct tcf_block *block;
183 struct Qdisc_class_hash clhash;
184
185 u64 oldV, V; /* Precise virtual times. */
186 struct qfq_aggregate *in_serv_agg; /* Aggregate being served. */
187 u32 wsum; /* weight sum */
188 u32 iwsum; /* inverse weight sum */
189
190 unsigned long bitmaps[QFQ_MAX_STATE]; /* Group bitmaps. */
191 struct qfq_group groups[QFQ_MAX_INDEX + 1]; /* The groups. */
192 u32 min_slot_shift; /* Index of the group-0 bit in the bitmaps. */
193
194 u32 max_agg_classes; /* Max number of classes per aggr. */
195 struct hlist_head nonfull_aggs; /* Aggs with room for more classes. */
196 };
197
198 /*
199 * Possible reasons why the timestamps of an aggregate are updated
200 * enqueue: the aggregate switches from idle to active and must scheduled
201 * for service
202 * requeue: the aggregate finishes its budget, so it stops being served and
203 * must be rescheduled for service
204 */
205 enum update_reason {enqueue, requeue};
206
qfq_find_class(struct Qdisc * sch,u32 classid)207 static struct qfq_class *qfq_find_class(struct Qdisc *sch, u32 classid)
208 {
209 struct qfq_sched *q = qdisc_priv(sch);
210 struct Qdisc_class_common *clc;
211
212 clc = qdisc_class_find(&q->clhash, classid);
213 if (clc == NULL)
214 return NULL;
215 return container_of(clc, struct qfq_class, common);
216 }
217
218 static struct netlink_range_validation lmax_range = {
219 .min = QFQ_MIN_LMAX,
220 .max = QFQ_MAX_LMAX,
221 };
222
223 static const struct nla_policy qfq_policy[TCA_QFQ_MAX + 1] = {
224 [TCA_QFQ_WEIGHT] = NLA_POLICY_RANGE(NLA_U32, 1, QFQ_MAX_WEIGHT),
225 [TCA_QFQ_LMAX] = NLA_POLICY_FULL_RANGE(NLA_U32, &lmax_range),
226 };
227
228 /*
229 * Calculate a flow index, given its weight and maximum packet length.
230 * index = log_2(maxlen/weight) but we need to apply the scaling.
231 * This is used only once at flow creation.
232 */
qfq_calc_index(u32 inv_w,unsigned int maxlen,u32 min_slot_shift)233 static int qfq_calc_index(u32 inv_w, unsigned int maxlen, u32 min_slot_shift)
234 {
235 u64 slot_size = (u64)maxlen * inv_w;
236 unsigned long size_map;
237 int index = 0;
238
239 size_map = slot_size >> min_slot_shift;
240 if (!size_map)
241 goto out;
242
243 index = __fls(size_map) + 1; /* basically a log_2 */
244 index -= !(slot_size - (1ULL << (index + min_slot_shift - 1)));
245
246 if (index < 0)
247 index = 0;
248 out:
249 pr_debug("qfq calc_index: W = %lu, L = %u, I = %d\n",
250 (unsigned long) ONE_FP/inv_w, maxlen, index);
251
252 return index;
253 }
254
255 static void qfq_deactivate_agg(struct qfq_sched *, struct qfq_aggregate *);
256 static void qfq_activate_agg(struct qfq_sched *, struct qfq_aggregate *,
257 enum update_reason);
258
qfq_init_agg(struct qfq_sched * q,struct qfq_aggregate * agg,u32 lmax,u32 weight)259 static void qfq_init_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
260 u32 lmax, u32 weight)
261 {
262 INIT_LIST_HEAD(&agg->active);
263 hlist_add_head(&agg->nonfull_next, &q->nonfull_aggs);
264
265 agg->lmax = lmax;
266 agg->class_weight = weight;
267 }
268
qfq_find_agg(struct qfq_sched * q,u32 lmax,u32 weight)269 static struct qfq_aggregate *qfq_find_agg(struct qfq_sched *q,
270 u32 lmax, u32 weight)
271 {
272 struct qfq_aggregate *agg;
273
274 hlist_for_each_entry(agg, &q->nonfull_aggs, nonfull_next)
275 if (agg->lmax == lmax && agg->class_weight == weight)
276 return agg;
277
278 return NULL;
279 }
280
281
282 /* Update aggregate as a function of the new number of classes. */
qfq_update_agg(struct qfq_sched * q,struct qfq_aggregate * agg,int new_num_classes)283 static void qfq_update_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
284 int new_num_classes)
285 {
286 u32 new_agg_weight;
287
288 if (new_num_classes == q->max_agg_classes)
289 hlist_del_init(&agg->nonfull_next);
290
291 if (agg->num_classes > new_num_classes &&
292 new_num_classes == q->max_agg_classes - 1) /* agg no more full */
293 hlist_add_head(&agg->nonfull_next, &q->nonfull_aggs);
294
295 /* The next assignment may let
296 * agg->initial_budget > agg->budgetmax
297 * hold, we will take it into account in charge_actual_service().
298 */
299 agg->budgetmax = new_num_classes * agg->lmax;
300 new_agg_weight = agg->class_weight * new_num_classes;
301 agg->inv_w = ONE_FP/new_agg_weight;
302
303 if (agg->grp == NULL) {
304 int i = qfq_calc_index(agg->inv_w, agg->budgetmax,
305 q->min_slot_shift);
306 agg->grp = &q->groups[i];
307 }
308
309 q->wsum +=
310 (int) agg->class_weight * (new_num_classes - agg->num_classes);
311 q->iwsum = ONE_FP / q->wsum;
312
313 agg->num_classes = new_num_classes;
314 }
315
316 /* Add class to aggregate. */
qfq_add_to_agg(struct qfq_sched * q,struct qfq_aggregate * agg,struct qfq_class * cl)317 static void qfq_add_to_agg(struct qfq_sched *q,
318 struct qfq_aggregate *agg,
319 struct qfq_class *cl)
320 {
321 cl->agg = agg;
322
323 qfq_update_agg(q, agg, agg->num_classes+1);
324 if (cl->qdisc->q.qlen > 0) { /* adding an active class */
325 list_add_tail(&cl->alist, &agg->active);
326 if (list_first_entry(&agg->active, struct qfq_class, alist) ==
327 cl && q->in_serv_agg != agg) /* agg was inactive */
328 qfq_activate_agg(q, agg, enqueue); /* schedule agg */
329 }
330 }
331
332 static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *);
333
qfq_destroy_agg(struct qfq_sched * q,struct qfq_aggregate * agg)334 static void qfq_destroy_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
335 {
336 hlist_del_init(&agg->nonfull_next);
337 q->wsum -= agg->class_weight;
338 if (q->wsum != 0)
339 q->iwsum = ONE_FP / q->wsum;
340
341 if (q->in_serv_agg == agg)
342 q->in_serv_agg = qfq_choose_next_agg(q);
343 kfree(agg);
344 }
345
346 /* Deschedule class from within its parent aggregate. */
qfq_deactivate_class(struct qfq_sched * q,struct qfq_class * cl)347 static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl)
348 {
349 struct qfq_aggregate *agg = cl->agg;
350
351
352 list_del(&cl->alist); /* remove from RR queue of the aggregate */
353 if (list_empty(&agg->active)) /* agg is now inactive */
354 qfq_deactivate_agg(q, agg);
355 }
356
357 /* Remove class from its parent aggregate. */
qfq_rm_from_agg(struct qfq_sched * q,struct qfq_class * cl)358 static void qfq_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl)
359 {
360 struct qfq_aggregate *agg = cl->agg;
361
362 cl->agg = NULL;
363 if (agg->num_classes == 1) { /* agg being emptied, destroy it */
364 qfq_destroy_agg(q, agg);
365 return;
366 }
367 qfq_update_agg(q, agg, agg->num_classes-1);
368 }
369
370 /* Deschedule class and remove it from its parent aggregate. */
qfq_deact_rm_from_agg(struct qfq_sched * q,struct qfq_class * cl)371 static void qfq_deact_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl)
372 {
373 if (cl->qdisc->q.qlen > 0) /* class is active */
374 qfq_deactivate_class(q, cl);
375
376 qfq_rm_from_agg(q, cl);
377 }
378
379 /* Move class to a new aggregate, matching the new class weight and/or lmax */
qfq_change_agg(struct Qdisc * sch,struct qfq_class * cl,u32 weight,u32 lmax)380 static int qfq_change_agg(struct Qdisc *sch, struct qfq_class *cl, u32 weight,
381 u32 lmax)
382 {
383 struct qfq_sched *q = qdisc_priv(sch);
384 struct qfq_aggregate *new_agg;
385
386 /* 'lmax' can range from [QFQ_MIN_LMAX, pktlen + stab overhead] */
387 if (lmax > QFQ_MAX_LMAX)
388 return -EINVAL;
389
390 new_agg = qfq_find_agg(q, lmax, weight);
391 if (new_agg == NULL) { /* create new aggregate */
392 new_agg = kzalloc(sizeof(*new_agg), GFP_ATOMIC);
393 if (new_agg == NULL)
394 return -ENOBUFS;
395 qfq_init_agg(q, new_agg, lmax, weight);
396 }
397 qfq_deact_rm_from_agg(q, cl);
398 qfq_add_to_agg(q, new_agg, cl);
399
400 return 0;
401 }
402
qfq_change_class(struct Qdisc * sch,u32 classid,u32 parentid,struct nlattr ** tca,unsigned long * arg,struct netlink_ext_ack * extack)403 static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
404 struct nlattr **tca, unsigned long *arg,
405 struct netlink_ext_ack *extack)
406 {
407 struct qfq_sched *q = qdisc_priv(sch);
408 struct qfq_class *cl = (struct qfq_class *)*arg;
409 bool existing = false;
410 struct nlattr *tb[TCA_QFQ_MAX + 1];
411 struct qfq_aggregate *new_agg = NULL;
412 u32 weight, lmax, inv_w;
413 int err;
414 int delta_w;
415
416 if (tca[TCA_OPTIONS] == NULL) {
417 pr_notice("qfq: no options\n");
418 return -EINVAL;
419 }
420
421 err = nla_parse_nested_deprecated(tb, TCA_QFQ_MAX, tca[TCA_OPTIONS],
422 qfq_policy, extack);
423 if (err < 0)
424 return err;
425
426 if (tb[TCA_QFQ_WEIGHT])
427 weight = nla_get_u32(tb[TCA_QFQ_WEIGHT]);
428 else
429 weight = 1;
430
431 if (tb[TCA_QFQ_LMAX]) {
432 lmax = nla_get_u32(tb[TCA_QFQ_LMAX]);
433 } else {
434 /* MTU size is user controlled */
435 lmax = psched_mtu(qdisc_dev(sch));
436 if (lmax < QFQ_MIN_LMAX || lmax > QFQ_MAX_LMAX) {
437 NL_SET_ERR_MSG_MOD(extack,
438 "MTU size out of bounds for qfq");
439 return -EINVAL;
440 }
441 }
442
443 inv_w = ONE_FP / weight;
444 weight = ONE_FP / inv_w;
445
446 if (cl != NULL &&
447 lmax == cl->agg->lmax &&
448 weight == cl->agg->class_weight)
449 return 0; /* nothing to change */
450
451 delta_w = weight - (cl ? cl->agg->class_weight : 0);
452
453 if (q->wsum + delta_w > QFQ_MAX_WSUM) {
454 pr_notice("qfq: total weight out of range (%d + %u)\n",
455 delta_w, q->wsum);
456 return -EINVAL;
457 }
458
459 if (cl != NULL) { /* modify existing class */
460 if (tca[TCA_RATE]) {
461 err = gen_replace_estimator(&cl->bstats, NULL,
462 &cl->rate_est,
463 NULL,
464 qdisc_root_sleeping_running(sch),
465 tca[TCA_RATE]);
466 if (err)
467 return err;
468 }
469 existing = true;
470 goto set_change_agg;
471 }
472
473 /* create and init new class */
474 cl = kzalloc(sizeof(struct qfq_class), GFP_KERNEL);
475 if (cl == NULL)
476 return -ENOBUFS;
477
478 cl->common.classid = classid;
479 cl->deficit = lmax;
480
481 cl->qdisc = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
482 classid, NULL);
483 if (cl->qdisc == NULL)
484 cl->qdisc = &noop_qdisc;
485
486 if (tca[TCA_RATE]) {
487 err = gen_new_estimator(&cl->bstats, NULL,
488 &cl->rate_est,
489 NULL,
490 qdisc_root_sleeping_running(sch),
491 tca[TCA_RATE]);
492 if (err)
493 goto destroy_class;
494 }
495
496 if (cl->qdisc != &noop_qdisc)
497 qdisc_hash_add(cl->qdisc, true);
498
499 set_change_agg:
500 sch_tree_lock(sch);
501 new_agg = qfq_find_agg(q, lmax, weight);
502 if (new_agg == NULL) { /* create new aggregate */
503 sch_tree_unlock(sch);
504 new_agg = kzalloc(sizeof(*new_agg), GFP_KERNEL);
505 if (new_agg == NULL) {
506 err = -ENOBUFS;
507 gen_kill_estimator(&cl->rate_est);
508 goto destroy_class;
509 }
510 sch_tree_lock(sch);
511 qfq_init_agg(q, 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, new_agg, cl);
518 sch_tree_unlock(sch);
519 qdisc_class_hash_grow(sch, &q->clhash);
520
521 *arg = (unsigned long)cl;
522 return 0;
523
524 destroy_class:
525 qdisc_put(cl->qdisc);
526 kfree(cl);
527 return err;
528 }
529
qfq_destroy_class(struct Qdisc * sch,struct qfq_class * cl)530 static 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(&cl->rate_est);
536 qdisc_put(cl->qdisc);
537 kfree(cl);
538 }
539
qfq_delete_class(struct Qdisc * sch,unsigned long arg,struct netlink_ext_ack * extack)540 static 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 (cl->filter_cnt > 0)
547 return -EBUSY;
548
549 sch_tree_lock(sch);
550
551 qdisc_purge_queue(cl->qdisc);
552 qdisc_class_hash_remove(&q->clhash, &cl->common);
553
554 sch_tree_unlock(sch);
555
556 qfq_destroy_class(sch, cl);
557 return 0;
558 }
559
qfq_search_class(struct Qdisc * sch,u32 classid)560 static unsigned long qfq_search_class(struct Qdisc *sch, u32 classid)
561 {
562 return (unsigned long)qfq_find_class(sch, classid);
563 }
564
qfq_tcf_block(struct Qdisc * sch,unsigned long cl,struct netlink_ext_ack * extack)565 static struct tcf_block *qfq_tcf_block(struct Qdisc *sch, unsigned long cl,
566 struct netlink_ext_ack *extack)
567 {
568 struct qfq_sched *q = qdisc_priv(sch);
569
570 if (cl)
571 return NULL;
572
573 return q->block;
574 }
575
qfq_bind_tcf(struct Qdisc * sch,unsigned long parent,u32 classid)576 static unsigned long qfq_bind_tcf(struct Qdisc *sch, unsigned long parent,
577 u32 classid)
578 {
579 struct qfq_class *cl = qfq_find_class(sch, classid);
580
581 if (cl != NULL)
582 cl->filter_cnt++;
583
584 return (unsigned long)cl;
585 }
586
qfq_unbind_tcf(struct Qdisc * sch,unsigned long arg)587 static void qfq_unbind_tcf(struct Qdisc *sch, unsigned long arg)
588 {
589 struct qfq_class *cl = (struct qfq_class *)arg;
590
591 cl->filter_cnt--;
592 }
593
qfq_graft_class(struct Qdisc * sch,unsigned long arg,struct Qdisc * new,struct Qdisc ** old,struct netlink_ext_ack * extack)594 static int qfq_graft_class(struct Qdisc *sch, unsigned long arg,
595 struct Qdisc *new, struct Qdisc **old,
596 struct netlink_ext_ack *extack)
597 {
598 struct qfq_class *cl = (struct qfq_class *)arg;
599
600 if (new == NULL) {
601 new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
602 cl->common.classid, NULL);
603 if (new == NULL)
604 new = &noop_qdisc;
605 }
606
607 *old = qdisc_replace(sch, new, &cl->qdisc);
608 return 0;
609 }
610
qfq_class_leaf(struct Qdisc * sch,unsigned long arg)611 static struct Qdisc *qfq_class_leaf(struct Qdisc *sch, unsigned long arg)
612 {
613 struct qfq_class *cl = (struct qfq_class *)arg;
614
615 return cl->qdisc;
616 }
617
qfq_dump_class(struct Qdisc * sch,unsigned long arg,struct sk_buff * skb,struct tcmsg * tcm)618 static int qfq_dump_class(struct Qdisc *sch, unsigned long arg,
619 struct sk_buff *skb, struct tcmsg *tcm)
620 {
621 struct qfq_class *cl = (struct qfq_class *)arg;
622 struct nlattr *nest;
623
624 tcm->tcm_parent = TC_H_ROOT;
625 tcm->tcm_handle = cl->common.classid;
626 tcm->tcm_info = cl->qdisc->handle;
627
628 nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
629 if (nest == NULL)
630 goto nla_put_failure;
631 if (nla_put_u32(skb, TCA_QFQ_WEIGHT, cl->agg->class_weight) ||
632 nla_put_u32(skb, TCA_QFQ_LMAX, cl->agg->lmax))
633 goto nla_put_failure;
634 return nla_nest_end(skb, nest);
635
636 nla_put_failure:
637 nla_nest_cancel(skb, nest);
638 return -EMSGSIZE;
639 }
640
qfq_dump_class_stats(struct Qdisc * sch,unsigned long arg,struct gnet_dump * d)641 static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg,
642 struct gnet_dump *d)
643 {
644 struct qfq_class *cl = (struct qfq_class *)arg;
645 struct tc_qfq_stats xstats;
646
647 memset(&xstats, 0, sizeof(xstats));
648
649 xstats.weight = cl->agg->class_weight;
650 xstats.lmax = cl->agg->lmax;
651
652 if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
653 d, NULL, &cl->bstats) < 0 ||
654 gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
655 qdisc_qstats_copy(d, cl->qdisc) < 0)
656 return -1;
657
658 return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
659 }
660
qfq_walk(struct Qdisc * sch,struct qdisc_walker * arg)661 static void qfq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
662 {
663 struct qfq_sched *q = qdisc_priv(sch);
664 struct qfq_class *cl;
665 unsigned int i;
666
667 if (arg->stop)
668 return;
669
670 for (i = 0; i < q->clhash.hashsize; i++) {
671 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
672 if (arg->count < arg->skip) {
673 arg->count++;
674 continue;
675 }
676 if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
677 arg->stop = 1;
678 return;
679 }
680 arg->count++;
681 }
682 }
683 }
684
qfq_classify(struct sk_buff * skb,struct Qdisc * sch,int * qerr)685 static struct qfq_class *qfq_classify(struct sk_buff *skb, struct Qdisc *sch,
686 int *qerr)
687 {
688 struct qfq_sched *q = qdisc_priv(sch);
689 struct qfq_class *cl;
690 struct tcf_result res;
691 struct tcf_proto *fl;
692 int result;
693
694 if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
695 pr_debug("qfq_classify: found %d\n", skb->priority);
696 cl = qfq_find_class(sch, skb->priority);
697 if (cl != NULL)
698 return cl;
699 }
700
701 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
702 fl = rcu_dereference_bh(q->filter_list);
703 result = tcf_classify(skb, NULL, fl, &res, false);
704 if (result >= 0) {
705 #ifdef CONFIG_NET_CLS_ACT
706 switch (result) {
707 case TC_ACT_QUEUED:
708 case TC_ACT_STOLEN:
709 case TC_ACT_TRAP:
710 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
711 fallthrough;
712 case TC_ACT_SHOT:
713 return NULL;
714 }
715 #endif
716 cl = (struct qfq_class *)res.class;
717 if (cl == NULL)
718 cl = qfq_find_class(sch, res.classid);
719 return cl;
720 }
721
722 return NULL;
723 }
724
725 /* Generic comparison function, handling wraparound. */
qfq_gt(u64 a,u64 b)726 static inline int qfq_gt(u64 a, u64 b)
727 {
728 return (s64)(a - b) > 0;
729 }
730
731 /* Round a precise timestamp to its slotted value. */
qfq_round_down(u64 ts,unsigned int shift)732 static inline u64 qfq_round_down(u64 ts, unsigned int shift)
733 {
734 return ts & ~((1ULL << shift) - 1);
735 }
736
737 /* return the pointer to the group with lowest index in the bitmap */
qfq_ffs(struct qfq_sched * q,unsigned long bitmap)738 static inline struct qfq_group *qfq_ffs(struct qfq_sched *q,
739 unsigned long bitmap)
740 {
741 int index = __ffs(bitmap);
742 return &q->groups[index];
743 }
744 /* Calculate a mask to mimic what would be ffs_from(). */
mask_from(unsigned long bitmap,int from)745 static inline unsigned long mask_from(unsigned long bitmap, int from)
746 {
747 return bitmap & ~((1UL << from) - 1);
748 }
749
750 /*
751 * The state computation relies on ER=0, IR=1, EB=2, IB=3
752 * First compute eligibility comparing grp->S, q->V,
753 * then check if someone is blocking us and possibly add EB
754 */
qfq_calc_state(struct qfq_sched * q,const struct qfq_group * grp)755 static int qfq_calc_state(struct qfq_sched *q, const struct qfq_group *grp)
756 {
757 /* if S > V we are not eligible */
758 unsigned int state = qfq_gt(grp->S, q->V);
759 unsigned long mask = mask_from(q->bitmaps[ER], grp->index);
760 struct qfq_group *next;
761
762 if (mask) {
763 next = qfq_ffs(q, mask);
764 if (qfq_gt(grp->F, next->F))
765 state |= EB;
766 }
767
768 return state;
769 }
770
771
772 /*
773 * In principle
774 * q->bitmaps[dst] |= q->bitmaps[src] & mask;
775 * q->bitmaps[src] &= ~mask;
776 * but we should make sure that src != dst
777 */
qfq_move_groups(struct qfq_sched * q,unsigned long mask,int src,int dst)778 static inline void qfq_move_groups(struct qfq_sched *q, unsigned long mask,
779 int src, int dst)
780 {
781 q->bitmaps[dst] |= q->bitmaps[src] & mask;
782 q->bitmaps[src] &= ~mask;
783 }
784
qfq_unblock_groups(struct qfq_sched * q,int index,u64 old_F)785 static void qfq_unblock_groups(struct qfq_sched *q, int index, u64 old_F)
786 {
787 unsigned long mask = mask_from(q->bitmaps[ER], index + 1);
788 struct qfq_group *next;
789
790 if (mask) {
791 next = qfq_ffs(q, mask);
792 if (!qfq_gt(next->F, old_F))
793 return;
794 }
795
796 mask = (1UL << index) - 1;
797 qfq_move_groups(q, mask, EB, ER);
798 qfq_move_groups(q, mask, IB, IR);
799 }
800
801 /*
802 * perhaps
803 *
804 old_V ^= q->V;
805 old_V >>= q->min_slot_shift;
806 if (old_V) {
807 ...
808 }
809 *
810 */
qfq_make_eligible(struct qfq_sched * q)811 static void qfq_make_eligible(struct qfq_sched *q)
812 {
813 unsigned long vslot = q->V >> q->min_slot_shift;
814 unsigned long old_vslot = q->oldV >> q->min_slot_shift;
815
816 if (vslot != old_vslot) {
817 unsigned long mask;
818 int last_flip_pos = fls(vslot ^ old_vslot);
819
820 if (last_flip_pos > 31) /* higher than the number of groups */
821 mask = ~0UL; /* make all groups eligible */
822 else
823 mask = (1UL << last_flip_pos) - 1;
824
825 qfq_move_groups(q, mask, IR, ER);
826 qfq_move_groups(q, mask, IB, EB);
827 }
828 }
829
830 /*
831 * The index of the slot in which the input aggregate agg is to be
832 * inserted must not be higher than QFQ_MAX_SLOTS-2. There is a '-2'
833 * and not a '-1' because the start time of the group may be moved
834 * backward by one slot after the aggregate has been inserted, and
835 * this would cause non-empty slots to be right-shifted by one
836 * position.
837 *
838 * QFQ+ fully satisfies this bound to the slot index if the parameters
839 * of the classes are not changed dynamically, and if QFQ+ never
840 * happens to postpone the service of agg unjustly, i.e., it never
841 * happens that the aggregate becomes backlogged and eligible, or just
842 * eligible, while an aggregate with a higher approximated finish time
843 * is being served. In particular, in this case QFQ+ guarantees that
844 * the timestamps of agg are low enough that the slot index is never
845 * higher than 2. Unfortunately, QFQ+ cannot provide the same
846 * guarantee if it happens to unjustly postpone the service of agg, or
847 * if the parameters of some class are changed.
848 *
849 * As for the first event, i.e., an out-of-order service, the
850 * upper bound to the slot index guaranteed by QFQ+ grows to
851 * 2 +
852 * QFQ_MAX_AGG_CLASSES * ((1<<QFQ_MTU_SHIFT)/QFQ_MIN_LMAX) *
853 * (current_max_weight/current_wsum) <= 2 + 8 * 128 * 1.
854 *
855 * The following function deals with this problem by backward-shifting
856 * the timestamps of agg, if needed, so as to guarantee that the slot
857 * index is never higher than QFQ_MAX_SLOTS-2. This backward-shift may
858 * cause the service of other aggregates to be postponed, yet the
859 * worst-case guarantees of these aggregates are not violated. In
860 * fact, in case of no out-of-order service, the timestamps of agg
861 * would have been even lower than they are after the backward shift,
862 * because QFQ+ would have guaranteed a maximum value equal to 2 for
863 * the slot index, and 2 < QFQ_MAX_SLOTS-2. Hence the aggregates whose
864 * service is postponed because of the backward-shift would have
865 * however waited for the service of agg before being served.
866 *
867 * The other event that may cause the slot index to be higher than 2
868 * for agg is a recent change of the parameters of some class. If the
869 * weight of a class is increased or the lmax (max_pkt_size) of the
870 * class is decreased, then a new aggregate with smaller slot size
871 * than the original parent aggregate of the class may happen to be
872 * activated. The activation of this aggregate should be properly
873 * delayed to when the service of the class has finished in the ideal
874 * system tracked by QFQ+. If the activation of the aggregate is not
875 * delayed to this reference time instant, then this aggregate may be
876 * unjustly served before other aggregates waiting for service. This
877 * may cause the above bound to the slot index to be violated for some
878 * of these unlucky aggregates.
879 *
880 * Instead of delaying the activation of the new aggregate, which is
881 * quite complex, the above-discussed capping of the slot index is
882 * used to handle also the consequences of a change of the parameters
883 * of a class.
884 */
qfq_slot_insert(struct qfq_group * grp,struct qfq_aggregate * agg,u64 roundedS)885 static void qfq_slot_insert(struct qfq_group *grp, struct qfq_aggregate *agg,
886 u64 roundedS)
887 {
888 u64 slot = (roundedS - grp->S) >> grp->slot_shift;
889 unsigned int i; /* slot index in the bucket list */
890
891 if (unlikely(slot > QFQ_MAX_SLOTS - 2)) {
892 u64 deltaS = roundedS - grp->S -
893 ((u64)(QFQ_MAX_SLOTS - 2)<<grp->slot_shift);
894 agg->S -= deltaS;
895 agg->F -= deltaS;
896 slot = QFQ_MAX_SLOTS - 2;
897 }
898
899 i = (grp->front + slot) % QFQ_MAX_SLOTS;
900
901 hlist_add_head(&agg->next, &grp->slots[i]);
902 __set_bit(slot, &grp->full_slots);
903 }
904
905 /* Maybe introduce hlist_first_entry?? */
qfq_slot_head(struct qfq_group * grp)906 static struct qfq_aggregate *qfq_slot_head(struct qfq_group *grp)
907 {
908 return hlist_entry(grp->slots[grp->front].first,
909 struct qfq_aggregate, next);
910 }
911
912 /*
913 * remove the entry from the slot
914 */
qfq_front_slot_remove(struct qfq_group * grp)915 static void qfq_front_slot_remove(struct qfq_group *grp)
916 {
917 struct qfq_aggregate *agg = qfq_slot_head(grp);
918
919 BUG_ON(!agg);
920 hlist_del(&agg->next);
921 if (hlist_empty(&grp->slots[grp->front]))
922 __clear_bit(0, &grp->full_slots);
923 }
924
925 /*
926 * Returns the first aggregate in the first non-empty bucket of the
927 * group. As a side effect, adjusts the bucket list so the first
928 * non-empty bucket is at position 0 in full_slots.
929 */
qfq_slot_scan(struct qfq_group * grp)930 static struct qfq_aggregate *qfq_slot_scan(struct qfq_group *grp)
931 {
932 unsigned int i;
933
934 pr_debug("qfq slot_scan: grp %u full %#lx\n",
935 grp->index, grp->full_slots);
936
937 if (grp->full_slots == 0)
938 return NULL;
939
940 i = __ffs(grp->full_slots); /* zero based */
941 if (i > 0) {
942 grp->front = (grp->front + i) % QFQ_MAX_SLOTS;
943 grp->full_slots >>= i;
944 }
945
946 return qfq_slot_head(grp);
947 }
948
949 /*
950 * adjust the bucket list. When the start time of a group decreases,
951 * we move the index down (modulo QFQ_MAX_SLOTS) so we don't need to
952 * move the objects. The mask of occupied slots must be shifted
953 * because we use ffs() to find the first non-empty slot.
954 * This covers decreases in the group's start time, but what about
955 * increases of the start time ?
956 * Here too we should make sure that i is less than 32
957 */
qfq_slot_rotate(struct qfq_group * grp,u64 roundedS)958 static void qfq_slot_rotate(struct qfq_group *grp, u64 roundedS)
959 {
960 unsigned int i = (grp->S - roundedS) >> grp->slot_shift;
961
962 grp->full_slots <<= i;
963 grp->front = (grp->front - i) % QFQ_MAX_SLOTS;
964 }
965
qfq_update_eligible(struct qfq_sched * q)966 static void qfq_update_eligible(struct qfq_sched *q)
967 {
968 struct qfq_group *grp;
969 unsigned long ineligible;
970
971 ineligible = q->bitmaps[IR] | q->bitmaps[IB];
972 if (ineligible) {
973 if (!q->bitmaps[ER]) {
974 grp = qfq_ffs(q, ineligible);
975 if (qfq_gt(grp->S, q->V))
976 q->V = grp->S;
977 }
978 qfq_make_eligible(q);
979 }
980 }
981
982 /* Dequeue head packet of the head class in the DRR queue of the aggregate. */
agg_dequeue(struct qfq_aggregate * agg,struct qfq_class * cl,unsigned int len)983 static struct sk_buff *agg_dequeue(struct qfq_aggregate *agg,
984 struct qfq_class *cl, unsigned int len)
985 {
986 struct sk_buff *skb = qdisc_dequeue_peeked(cl->qdisc);
987
988 if (!skb)
989 return NULL;
990
991 cl->deficit -= (int) len;
992
993 if (cl->qdisc->q.qlen == 0) /* no more packets, remove from list */
994 list_del(&cl->alist);
995 else if (cl->deficit < qdisc_pkt_len(cl->qdisc->ops->peek(cl->qdisc))) {
996 cl->deficit += agg->lmax;
997 list_move_tail(&cl->alist, &agg->active);
998 }
999
1000 return skb;
1001 }
1002
qfq_peek_skb(struct qfq_aggregate * agg,struct qfq_class ** cl,unsigned int * len)1003 static inline struct sk_buff *qfq_peek_skb(struct qfq_aggregate *agg,
1004 struct qfq_class **cl,
1005 unsigned int *len)
1006 {
1007 struct sk_buff *skb;
1008
1009 *cl = list_first_entry(&agg->active, struct qfq_class, alist);
1010 skb = (*cl)->qdisc->ops->peek((*cl)->qdisc);
1011 if (skb == NULL)
1012 WARN_ONCE(1, "qfq_dequeue: non-workconserving leaf\n");
1013 else
1014 *len = qdisc_pkt_len(skb);
1015
1016 return skb;
1017 }
1018
1019 /* Update F according to the actual service received by the aggregate. */
charge_actual_service(struct qfq_aggregate * agg)1020 static inline void charge_actual_service(struct qfq_aggregate *agg)
1021 {
1022 /* Compute the service received by the aggregate, taking into
1023 * account that, after decreasing the number of classes in
1024 * agg, it may happen that
1025 * agg->initial_budget - agg->budget > agg->bugdetmax
1026 */
1027 u32 service_received = min(agg->budgetmax,
1028 agg->initial_budget - agg->budget);
1029
1030 agg->F = agg->S + (u64)service_received * agg->inv_w;
1031 }
1032
1033 /* Assign a reasonable start time for a new aggregate in group i.
1034 * Admissible values for \hat(F) are multiples of \sigma_i
1035 * no greater than V+\sigma_i . Larger values mean that
1036 * we had a wraparound so we consider the timestamp to be stale.
1037 *
1038 * If F is not stale and F >= V then we set S = F.
1039 * Otherwise we should assign S = V, but this may violate
1040 * the ordering in EB (see [2]). So, if we have groups in ER,
1041 * set S to the F_j of the first group j which would be blocking us.
1042 * We are guaranteed not to move S backward because
1043 * otherwise our group i would still be blocked.
1044 */
qfq_update_start(struct qfq_sched * q,struct qfq_aggregate * agg)1045 static void qfq_update_start(struct qfq_sched *q, struct qfq_aggregate *agg)
1046 {
1047 unsigned long mask;
1048 u64 limit, roundedF;
1049 int slot_shift = agg->grp->slot_shift;
1050
1051 roundedF = qfq_round_down(agg->F, slot_shift);
1052 limit = qfq_round_down(q->V, slot_shift) + (1ULL << slot_shift);
1053
1054 if (!qfq_gt(agg->F, q->V) || qfq_gt(roundedF, limit)) {
1055 /* timestamp was stale */
1056 mask = mask_from(q->bitmaps[ER], agg->grp->index);
1057 if (mask) {
1058 struct qfq_group *next = qfq_ffs(q, mask);
1059 if (qfq_gt(roundedF, next->F)) {
1060 if (qfq_gt(limit, next->F))
1061 agg->S = next->F;
1062 else /* preserve timestamp correctness */
1063 agg->S = limit;
1064 return;
1065 }
1066 }
1067 agg->S = q->V;
1068 } else /* timestamp is not stale */
1069 agg->S = agg->F;
1070 }
1071
1072 /* Update the timestamps of agg before scheduling/rescheduling it for
1073 * service. In particular, assign to agg->F its maximum possible
1074 * value, i.e., the virtual finish time with which the aggregate
1075 * should be labeled if it used all its budget once in service.
1076 */
1077 static inline void
qfq_update_agg_ts(struct qfq_sched * q,struct qfq_aggregate * agg,enum update_reason reason)1078 qfq_update_agg_ts(struct qfq_sched *q,
1079 struct qfq_aggregate *agg, enum update_reason reason)
1080 {
1081 if (reason != requeue)
1082 qfq_update_start(q, agg);
1083 else /* just charge agg for the service received */
1084 agg->S = agg->F;
1085
1086 agg->F = agg->S + (u64)agg->budgetmax * agg->inv_w;
1087 }
1088
1089 static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg);
1090
qfq_dequeue(struct Qdisc * sch)1091 static struct sk_buff *qfq_dequeue(struct Qdisc *sch)
1092 {
1093 struct qfq_sched *q = qdisc_priv(sch);
1094 struct qfq_aggregate *in_serv_agg = q->in_serv_agg;
1095 struct qfq_class *cl;
1096 struct sk_buff *skb = NULL;
1097 /* next-packet len, 0 means no more active classes in in-service agg */
1098 unsigned int len = 0;
1099
1100 if (in_serv_agg == NULL)
1101 return NULL;
1102
1103 if (!list_empty(&in_serv_agg->active))
1104 skb = qfq_peek_skb(in_serv_agg, &cl, &len);
1105
1106 /*
1107 * If there are no active classes in the in-service aggregate,
1108 * or if the aggregate has not enough budget to serve its next
1109 * class, then choose the next aggregate to serve.
1110 */
1111 if (len == 0 || in_serv_agg->budget < len) {
1112 charge_actual_service(in_serv_agg);
1113
1114 /* recharge the budget of the aggregate */
1115 in_serv_agg->initial_budget = in_serv_agg->budget =
1116 in_serv_agg->budgetmax;
1117
1118 if (!list_empty(&in_serv_agg->active)) {
1119 /*
1120 * Still active: reschedule for
1121 * service. Possible optimization: if no other
1122 * aggregate is active, then there is no point
1123 * in rescheduling this aggregate, and we can
1124 * just keep it as the in-service one. This
1125 * should be however a corner case, and to
1126 * handle it, we would need to maintain an
1127 * extra num_active_aggs field.
1128 */
1129 qfq_update_agg_ts(q, in_serv_agg, requeue);
1130 qfq_schedule_agg(q, in_serv_agg);
1131 } else if (sch->q.qlen == 0) { /* no aggregate to serve */
1132 q->in_serv_agg = NULL;
1133 return NULL;
1134 }
1135
1136 /*
1137 * If we get here, there are other aggregates queued:
1138 * choose the new aggregate to serve.
1139 */
1140 in_serv_agg = q->in_serv_agg = qfq_choose_next_agg(q);
1141 skb = qfq_peek_skb(in_serv_agg, &cl, &len);
1142 }
1143 if (!skb)
1144 return NULL;
1145
1146 sch->q.qlen--;
1147
1148 skb = agg_dequeue(in_serv_agg, cl, len);
1149
1150 if (!skb) {
1151 sch->q.qlen++;
1152 return NULL;
1153 }
1154
1155 qdisc_qstats_backlog_dec(sch, skb);
1156 qdisc_bstats_update(sch, skb);
1157
1158 /* If lmax is lowered, through qfq_change_class, for a class
1159 * owning pending packets with larger size than the new value
1160 * of lmax, then the following condition may hold.
1161 */
1162 if (unlikely(in_serv_agg->budget < len))
1163 in_serv_agg->budget = 0;
1164 else
1165 in_serv_agg->budget -= len;
1166
1167 q->V += (u64)len * q->iwsum;
1168 pr_debug("qfq dequeue: len %u F %lld now %lld\n",
1169 len, (unsigned long long) in_serv_agg->F,
1170 (unsigned long long) q->V);
1171
1172 return skb;
1173 }
1174
qfq_choose_next_agg(struct qfq_sched * q)1175 static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *q)
1176 {
1177 struct qfq_group *grp;
1178 struct qfq_aggregate *agg, *new_front_agg;
1179 u64 old_F;
1180
1181 qfq_update_eligible(q);
1182 q->oldV = q->V;
1183
1184 if (!q->bitmaps[ER])
1185 return NULL;
1186
1187 grp = qfq_ffs(q, q->bitmaps[ER]);
1188 old_F = grp->F;
1189
1190 agg = qfq_slot_head(grp);
1191
1192 /* agg starts to be served, remove it from schedule */
1193 qfq_front_slot_remove(grp);
1194
1195 new_front_agg = qfq_slot_scan(grp);
1196
1197 if (new_front_agg == NULL) /* group is now inactive, remove from ER */
1198 __clear_bit(grp->index, &q->bitmaps[ER]);
1199 else {
1200 u64 roundedS = qfq_round_down(new_front_agg->S,
1201 grp->slot_shift);
1202 unsigned int s;
1203
1204 if (grp->S == roundedS)
1205 return agg;
1206 grp->S = roundedS;
1207 grp->F = roundedS + (2ULL << grp->slot_shift);
1208 __clear_bit(grp->index, &q->bitmaps[ER]);
1209 s = qfq_calc_state(q, grp);
1210 __set_bit(grp->index, &q->bitmaps[s]);
1211 }
1212
1213 qfq_unblock_groups(q, grp->index, old_F);
1214
1215 return agg;
1216 }
1217
qfq_enqueue(struct sk_buff * skb,struct Qdisc * sch,struct sk_buff ** to_free)1218 static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
1219 struct sk_buff **to_free)
1220 {
1221 unsigned int len = qdisc_pkt_len(skb), gso_segs;
1222 struct qfq_sched *q = qdisc_priv(sch);
1223 struct qfq_class *cl;
1224 struct qfq_aggregate *agg;
1225 int err = 0;
1226 bool first;
1227
1228 cl = qfq_classify(skb, sch, &err);
1229 if (cl == NULL) {
1230 if (err & __NET_XMIT_BYPASS)
1231 qdisc_qstats_drop(sch);
1232 __qdisc_drop(skb, to_free);
1233 return err;
1234 }
1235 pr_debug("qfq_enqueue: cl = %x\n", cl->common.classid);
1236
1237 if (unlikely(cl->agg->lmax < len)) {
1238 pr_debug("qfq: increasing maxpkt from %u to %u for class %u",
1239 cl->agg->lmax, len, cl->common.classid);
1240 err = qfq_change_agg(sch, cl, cl->agg->class_weight, len);
1241 if (err) {
1242 cl->qstats.drops++;
1243 return qdisc_drop(skb, sch, to_free);
1244 }
1245 }
1246
1247 gso_segs = skb_is_gso(skb) ? skb_shinfo(skb)->gso_segs : 1;
1248 first = !cl->qdisc->q.qlen;
1249 err = qdisc_enqueue(skb, cl->qdisc, to_free);
1250 if (unlikely(err != NET_XMIT_SUCCESS)) {
1251 pr_debug("qfq_enqueue: enqueue failed %d\n", err);
1252 if (net_xmit_drop_count(err)) {
1253 cl->qstats.drops++;
1254 qdisc_qstats_drop(sch);
1255 }
1256 return err;
1257 }
1258
1259 cl->bstats.bytes += len;
1260 cl->bstats.packets += gso_segs;
1261 sch->qstats.backlog += len;
1262 ++sch->q.qlen;
1263
1264 agg = cl->agg;
1265 /* if the queue was not empty, then done here */
1266 if (!first) {
1267 if (unlikely(skb == cl->qdisc->ops->peek(cl->qdisc)) &&
1268 list_first_entry(&agg->active, struct qfq_class, alist)
1269 == cl && cl->deficit < len)
1270 list_move_tail(&cl->alist, &agg->active);
1271
1272 return err;
1273 }
1274
1275 /* schedule class for service within the aggregate */
1276 cl->deficit = agg->lmax;
1277 list_add_tail(&cl->alist, &agg->active);
1278
1279 if (list_first_entry(&agg->active, struct qfq_class, alist) != cl ||
1280 q->in_serv_agg == agg)
1281 return err; /* non-empty or in service, nothing else to do */
1282
1283 qfq_activate_agg(q, agg, enqueue);
1284
1285 return err;
1286 }
1287
1288 /*
1289 * Schedule aggregate according to its timestamps.
1290 */
qfq_schedule_agg(struct qfq_sched * q,struct qfq_aggregate * agg)1291 static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
1292 {
1293 struct qfq_group *grp = agg->grp;
1294 u64 roundedS;
1295 int s;
1296
1297 roundedS = qfq_round_down(agg->S, grp->slot_shift);
1298
1299 /*
1300 * Insert agg in the correct bucket.
1301 * If agg->S >= grp->S we don't need to adjust the
1302 * bucket list and simply go to the insertion phase.
1303 * Otherwise grp->S is decreasing, we must make room
1304 * in the bucket list, and also recompute the group state.
1305 * Finally, if there were no flows in this group and nobody
1306 * was in ER make sure to adjust V.
1307 */
1308 if (grp->full_slots) {
1309 if (!qfq_gt(grp->S, agg->S))
1310 goto skip_update;
1311
1312 /* create a slot for this agg->S */
1313 qfq_slot_rotate(grp, roundedS);
1314 /* group was surely ineligible, remove */
1315 __clear_bit(grp->index, &q->bitmaps[IR]);
1316 __clear_bit(grp->index, &q->bitmaps[IB]);
1317 } else if (!q->bitmaps[ER] && qfq_gt(roundedS, q->V) &&
1318 q->in_serv_agg == NULL)
1319 q->V = roundedS;
1320
1321 grp->S = roundedS;
1322 grp->F = roundedS + (2ULL << grp->slot_shift);
1323 s = qfq_calc_state(q, grp);
1324 __set_bit(grp->index, &q->bitmaps[s]);
1325
1326 pr_debug("qfq enqueue: new state %d %#lx S %lld F %lld V %lld\n",
1327 s, q->bitmaps[s],
1328 (unsigned long long) agg->S,
1329 (unsigned long long) agg->F,
1330 (unsigned long long) q->V);
1331
1332 skip_update:
1333 qfq_slot_insert(grp, agg, roundedS);
1334 }
1335
1336
1337 /* Update agg ts and schedule agg for service */
qfq_activate_agg(struct qfq_sched * q,struct qfq_aggregate * agg,enum update_reason reason)1338 static void qfq_activate_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
1339 enum update_reason reason)
1340 {
1341 agg->initial_budget = agg->budget = agg->budgetmax; /* recharge budg. */
1342
1343 qfq_update_agg_ts(q, agg, reason);
1344 if (q->in_serv_agg == NULL) { /* no aggr. in service or scheduled */
1345 q->in_serv_agg = agg; /* start serving this aggregate */
1346 /* update V: to be in service, agg must be eligible */
1347 q->oldV = q->V = agg->S;
1348 } else if (agg != q->in_serv_agg)
1349 qfq_schedule_agg(q, agg);
1350 }
1351
qfq_slot_remove(struct qfq_sched * q,struct qfq_group * grp,struct qfq_aggregate * agg)1352 static void qfq_slot_remove(struct qfq_sched *q, struct qfq_group *grp,
1353 struct qfq_aggregate *agg)
1354 {
1355 unsigned int i, offset;
1356 u64 roundedS;
1357
1358 roundedS = qfq_round_down(agg->S, grp->slot_shift);
1359 offset = (roundedS - grp->S) >> grp->slot_shift;
1360
1361 i = (grp->front + offset) % QFQ_MAX_SLOTS;
1362
1363 hlist_del(&agg->next);
1364 if (hlist_empty(&grp->slots[i]))
1365 __clear_bit(offset, &grp->full_slots);
1366 }
1367
1368 /*
1369 * Called to forcibly deschedule an aggregate. If the aggregate is
1370 * not in the front bucket, or if the latter has other aggregates in
1371 * the front bucket, we can simply remove the aggregate with no other
1372 * side effects.
1373 * Otherwise we must propagate the event up.
1374 */
qfq_deactivate_agg(struct qfq_sched * q,struct qfq_aggregate * agg)1375 static void qfq_deactivate_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
1376 {
1377 struct qfq_group *grp = agg->grp;
1378 unsigned long mask;
1379 u64 roundedS;
1380 int s;
1381
1382 if (agg == q->in_serv_agg) {
1383 charge_actual_service(agg);
1384 q->in_serv_agg = qfq_choose_next_agg(q);
1385 return;
1386 }
1387
1388 agg->F = agg->S;
1389 qfq_slot_remove(q, grp, agg);
1390
1391 if (!grp->full_slots) {
1392 __clear_bit(grp->index, &q->bitmaps[IR]);
1393 __clear_bit(grp->index, &q->bitmaps[EB]);
1394 __clear_bit(grp->index, &q->bitmaps[IB]);
1395
1396 if (test_bit(grp->index, &q->bitmaps[ER]) &&
1397 !(q->bitmaps[ER] & ~((1UL << grp->index) - 1))) {
1398 mask = q->bitmaps[ER] & ((1UL << grp->index) - 1);
1399 if (mask)
1400 mask = ~((1UL << __fls(mask)) - 1);
1401 else
1402 mask = ~0UL;
1403 qfq_move_groups(q, mask, EB, ER);
1404 qfq_move_groups(q, mask, IB, IR);
1405 }
1406 __clear_bit(grp->index, &q->bitmaps[ER]);
1407 } else if (hlist_empty(&grp->slots[grp->front])) {
1408 agg = qfq_slot_scan(grp);
1409 roundedS = qfq_round_down(agg->S, grp->slot_shift);
1410 if (grp->S != roundedS) {
1411 __clear_bit(grp->index, &q->bitmaps[ER]);
1412 __clear_bit(grp->index, &q->bitmaps[IR]);
1413 __clear_bit(grp->index, &q->bitmaps[EB]);
1414 __clear_bit(grp->index, &q->bitmaps[IB]);
1415 grp->S = roundedS;
1416 grp->F = roundedS + (2ULL << grp->slot_shift);
1417 s = qfq_calc_state(q, grp);
1418 __set_bit(grp->index, &q->bitmaps[s]);
1419 }
1420 }
1421 }
1422
qfq_qlen_notify(struct Qdisc * sch,unsigned long arg)1423 static void qfq_qlen_notify(struct Qdisc *sch, unsigned long arg)
1424 {
1425 struct qfq_sched *q = qdisc_priv(sch);
1426 struct qfq_class *cl = (struct qfq_class *)arg;
1427
1428 qfq_deactivate_class(q, cl);
1429 }
1430
qfq_init_qdisc(struct Qdisc * sch,struct nlattr * opt,struct netlink_ext_ack * extack)1431 static int qfq_init_qdisc(struct Qdisc *sch, struct nlattr *opt,
1432 struct netlink_ext_ack *extack)
1433 {
1434 struct qfq_sched *q = qdisc_priv(sch);
1435 struct qfq_group *grp;
1436 int i, j, err;
1437 u32 max_cl_shift, maxbudg_shift, max_classes;
1438
1439 err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
1440 if (err)
1441 return err;
1442
1443 err = qdisc_class_hash_init(&q->clhash);
1444 if (err < 0)
1445 return err;
1446
1447 max_classes = min_t(u64, (u64)qdisc_dev(sch)->tx_queue_len + 1,
1448 QFQ_MAX_AGG_CLASSES);
1449 /* max_cl_shift = floor(log_2(max_classes)) */
1450 max_cl_shift = __fls(max_classes);
1451 q->max_agg_classes = 1<<max_cl_shift;
1452
1453 /* maxbudg_shift = log2(max_len * max_classes_per_agg) */
1454 maxbudg_shift = QFQ_MTU_SHIFT + max_cl_shift;
1455 q->min_slot_shift = FRAC_BITS + maxbudg_shift - QFQ_MAX_INDEX;
1456
1457 for (i = 0; i <= QFQ_MAX_INDEX; i++) {
1458 grp = &q->groups[i];
1459 grp->index = i;
1460 grp->slot_shift = q->min_slot_shift + i;
1461 for (j = 0; j < QFQ_MAX_SLOTS; j++)
1462 INIT_HLIST_HEAD(&grp->slots[j]);
1463 }
1464
1465 INIT_HLIST_HEAD(&q->nonfull_aggs);
1466
1467 return 0;
1468 }
1469
qfq_reset_qdisc(struct Qdisc * sch)1470 static void qfq_reset_qdisc(struct Qdisc *sch)
1471 {
1472 struct qfq_sched *q = qdisc_priv(sch);
1473 struct qfq_class *cl;
1474 unsigned int i;
1475
1476 for (i = 0; i < q->clhash.hashsize; i++) {
1477 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
1478 if (cl->qdisc->q.qlen > 0)
1479 qfq_deactivate_class(q, cl);
1480
1481 qdisc_reset(cl->qdisc);
1482 }
1483 }
1484 }
1485
qfq_destroy_qdisc(struct Qdisc * sch)1486 static void qfq_destroy_qdisc(struct Qdisc *sch)
1487 {
1488 struct qfq_sched *q = qdisc_priv(sch);
1489 struct qfq_class *cl;
1490 struct hlist_node *next;
1491 unsigned int i;
1492
1493 tcf_block_put(q->block);
1494
1495 for (i = 0; i < q->clhash.hashsize; i++) {
1496 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],
1497 common.hnode) {
1498 qfq_destroy_class(sch, cl);
1499 }
1500 }
1501 qdisc_class_hash_destroy(&q->clhash);
1502 }
1503
1504 static const struct Qdisc_class_ops qfq_class_ops = {
1505 .change = qfq_change_class,
1506 .delete = qfq_delete_class,
1507 .find = qfq_search_class,
1508 .tcf_block = qfq_tcf_block,
1509 .bind_tcf = qfq_bind_tcf,
1510 .unbind_tcf = qfq_unbind_tcf,
1511 .graft = qfq_graft_class,
1512 .leaf = qfq_class_leaf,
1513 .qlen_notify = qfq_qlen_notify,
1514 .dump = qfq_dump_class,
1515 .dump_stats = qfq_dump_class_stats,
1516 .walk = qfq_walk,
1517 };
1518
1519 static struct Qdisc_ops qfq_qdisc_ops __read_mostly = {
1520 .cl_ops = &qfq_class_ops,
1521 .id = "qfq",
1522 .priv_size = sizeof(struct qfq_sched),
1523 .enqueue = qfq_enqueue,
1524 .dequeue = qfq_dequeue,
1525 .peek = qdisc_peek_dequeued,
1526 .init = qfq_init_qdisc,
1527 .reset = qfq_reset_qdisc,
1528 .destroy = qfq_destroy_qdisc,
1529 .owner = THIS_MODULE,
1530 };
1531
qfq_init(void)1532 static int __init qfq_init(void)
1533 {
1534 return register_qdisc(&qfq_qdisc_ops);
1535 }
1536
qfq_exit(void)1537 static void __exit qfq_exit(void)
1538 {
1539 unregister_qdisc(&qfq_qdisc_ops);
1540 }
1541
1542 module_init(qfq_init);
1543 module_exit(qfq_exit);
1544 MODULE_LICENSE("GPL");
1545