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Linux/net/sched/sch_qfq.c

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

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