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Linux/net/sched/sch_qfq.c

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

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