~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/net/sched/sch_qfq.c

Version: ~ [ linux-5.13-rc5 ] ~ [ linux-5.12.9 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.42 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.124 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.193 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.235 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.271 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.271 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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 refcnt;
136         unsigned int filter_cnt;
137 
138         struct gnet_stats_basic_packed bstats;
139         struct gnet_stats_queue qstats;
140         struct gnet_stats_rate_est64 rate_est;
141         struct Qdisc *qdisc;
142         struct list_head alist;         /* Link for active-classes list. */
143         struct qfq_aggregate *agg;      /* Parent aggregate. */
144         int deficit;                    /* DRR deficit counter. */
145 };
146 
147 struct qfq_aggregate {
148         struct hlist_node next; /* Link for the slot list. */
149         u64 S, F;               /* flow timestamps (exact) */
150 
151         /* group we belong to. In principle we would need the index,
152          * which is log_2(lmax/weight), but we never reference it
153          * directly, only the group.
154          */
155         struct qfq_group *grp;
156 
157         /* these are copied from the flowset. */
158         u32     class_weight; /* Weight of each class in this aggregate. */
159         /* Max pkt size for the classes in this aggregate, DRR quantum. */
160         int     lmax;
161 
162         u32     inv_w;      /* ONE_FP/(sum of weights of classes in aggr.). */
163         u32     budgetmax;  /* Max budget for this aggregate. */
164         u32     initial_budget, budget;     /* Initial and current budget. */
165 
166         int               num_classes;  /* Number of classes in this aggr. */
167         struct list_head  active;       /* DRR queue of active classes. */
168 
169         struct hlist_node nonfull_next; /* See nonfull_aggs in qfq_sched. */
170 };
171 
172 struct qfq_group {
173         u64 S, F;                       /* group timestamps (approx). */
174         unsigned int slot_shift;        /* Slot shift. */
175         unsigned int index;             /* Group index. */
176         unsigned int front;             /* Index of the front slot. */
177         unsigned long full_slots;       /* non-empty slots */
178 
179         /* Array of RR lists of active aggregates. */
180         struct hlist_head slots[QFQ_MAX_SLOTS];
181 };
182 
183 struct qfq_sched {
184         struct tcf_proto __rcu *filter_list;
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 void qfq_purge_queue(struct qfq_class *cl)
221 {
222         unsigned int len = cl->qdisc->q.qlen;
223         unsigned int backlog = cl->qdisc->qstats.backlog;
224 
225         qdisc_reset(cl->qdisc);
226         qdisc_tree_reduce_backlog(cl->qdisc, len, backlog);
227 }
228 
229 static const struct nla_policy qfq_policy[TCA_QFQ_MAX + 1] = {
230         [TCA_QFQ_WEIGHT] = { .type = NLA_U32 },
231         [TCA_QFQ_LMAX] = { .type = NLA_U32 },
232 };
233 
234 /*
235  * Calculate a flow index, given its weight and maximum packet length.
236  * index = log_2(maxlen/weight) but we need to apply the scaling.
237  * This is used only once at flow creation.
238  */
239 static int qfq_calc_index(u32 inv_w, unsigned int maxlen, u32 min_slot_shift)
240 {
241         u64 slot_size = (u64)maxlen * inv_w;
242         unsigned long size_map;
243         int index = 0;
244 
245         size_map = slot_size >> min_slot_shift;
246         if (!size_map)
247                 goto out;
248 
249         index = __fls(size_map) + 1;    /* basically a log_2 */
250         index -= !(slot_size - (1ULL << (index + min_slot_shift - 1)));
251 
252         if (index < 0)
253                 index = 0;
254 out:
255         pr_debug("qfq calc_index: W = %lu, L = %u, I = %d\n",
256                  (unsigned long) ONE_FP/inv_w, maxlen, index);
257 
258         return index;
259 }
260 
261 static void qfq_deactivate_agg(struct qfq_sched *, struct qfq_aggregate *);
262 static void qfq_activate_agg(struct qfq_sched *, struct qfq_aggregate *,
263                              enum update_reason);
264 
265 static void qfq_init_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
266                          u32 lmax, u32 weight)
267 {
268         INIT_LIST_HEAD(&agg->active);
269         hlist_add_head(&agg->nonfull_next, &q->nonfull_aggs);
270 
271         agg->lmax = lmax;
272         agg->class_weight = weight;
273 }
274 
275 static struct qfq_aggregate *qfq_find_agg(struct qfq_sched *q,
276                                           u32 lmax, u32 weight)
277 {
278         struct qfq_aggregate *agg;
279 
280         hlist_for_each_entry(agg, &q->nonfull_aggs, nonfull_next)
281                 if (agg->lmax == lmax && agg->class_weight == weight)
282                         return agg;
283 
284         return NULL;
285 }
286 
287 
288 /* Update aggregate as a function of the new number of classes. */
289 static void qfq_update_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
290                            int new_num_classes)
291 {
292         u32 new_agg_weight;
293 
294         if (new_num_classes == q->max_agg_classes)
295                 hlist_del_init(&agg->nonfull_next);
296 
297         if (agg->num_classes > new_num_classes &&
298             new_num_classes == q->max_agg_classes - 1) /* agg no more full */
299                 hlist_add_head(&agg->nonfull_next, &q->nonfull_aggs);
300 
301         /* The next assignment may let
302          * agg->initial_budget > agg->budgetmax
303          * hold, we will take it into account in charge_actual_service().
304          */
305         agg->budgetmax = new_num_classes * agg->lmax;
306         new_agg_weight = agg->class_weight * new_num_classes;
307         agg->inv_w = ONE_FP/new_agg_weight;
308 
309         if (agg->grp == NULL) {
310                 int i = qfq_calc_index(agg->inv_w, agg->budgetmax,
311                                        q->min_slot_shift);
312                 agg->grp = &q->groups[i];
313         }
314 
315         q->wsum +=
316                 (int) agg->class_weight * (new_num_classes - agg->num_classes);
317         q->iwsum = ONE_FP / q->wsum;
318 
319         agg->num_classes = new_num_classes;
320 }
321 
322 /* Add class to aggregate. */
323 static void qfq_add_to_agg(struct qfq_sched *q,
324                            struct qfq_aggregate *agg,
325                            struct qfq_class *cl)
326 {
327         cl->agg = agg;
328 
329         qfq_update_agg(q, agg, agg->num_classes+1);
330         if (cl->qdisc->q.qlen > 0) { /* adding an active class */
331                 list_add_tail(&cl->alist, &agg->active);
332                 if (list_first_entry(&agg->active, struct qfq_class, alist) ==
333                     cl && q->in_serv_agg != agg) /* agg was inactive */
334                         qfq_activate_agg(q, agg, enqueue); /* schedule agg */
335         }
336 }
337 
338 static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *);
339 
340 static void qfq_destroy_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
341 {
342         hlist_del_init(&agg->nonfull_next);
343         q->wsum -= agg->class_weight;
344         if (q->wsum != 0)
345                 q->iwsum = ONE_FP / q->wsum;
346 
347         if (q->in_serv_agg == agg)
348                 q->in_serv_agg = qfq_choose_next_agg(q);
349         kfree(agg);
350 }
351 
352 /* Deschedule class from within its parent aggregate. */
353 static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl)
354 {
355         struct qfq_aggregate *agg = cl->agg;
356 
357 
358         list_del(&cl->alist); /* remove from RR queue of the aggregate */
359         if (list_empty(&agg->active)) /* agg is now inactive */
360                 qfq_deactivate_agg(q, agg);
361 }
362 
363 /* Remove class from its parent aggregate. */
364 static void qfq_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl)
365 {
366         struct qfq_aggregate *agg = cl->agg;
367 
368         cl->agg = NULL;
369         if (agg->num_classes == 1) { /* agg being emptied, destroy it */
370                 qfq_destroy_agg(q, agg);
371                 return;
372         }
373         qfq_update_agg(q, agg, agg->num_classes-1);
374 }
375 
376 /* Deschedule class and remove it from its parent aggregate. */
377 static void qfq_deact_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl)
378 {
379         if (cl->qdisc->q.qlen > 0) /* class is active */
380                 qfq_deactivate_class(q, cl);
381 
382         qfq_rm_from_agg(q, cl);
383 }
384 
385 /* Move class to a new aggregate, matching the new class weight and/or lmax */
386 static int qfq_change_agg(struct Qdisc *sch, struct qfq_class *cl, u32 weight,
387                            u32 lmax)
388 {
389         struct qfq_sched *q = qdisc_priv(sch);
390         struct qfq_aggregate *new_agg = qfq_find_agg(q, lmax, weight);
391 
392         if (new_agg == NULL) { /* create new aggregate */
393                 new_agg = kzalloc(sizeof(*new_agg), GFP_ATOMIC);
394                 if (new_agg == NULL)
395                         return -ENOBUFS;
396                 qfq_init_agg(q, new_agg, lmax, weight);
397         }
398         qfq_deact_rm_from_agg(q, cl);
399         qfq_add_to_agg(q, new_agg, cl);
400 
401         return 0;
402 }
403 
404 static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
405                             struct nlattr **tca, unsigned long *arg)
406 {
407         struct qfq_sched *q = qdisc_priv(sch);
408         struct qfq_class *cl = (struct qfq_class *)*arg;
409         bool existing = false;
410         struct nlattr *tb[TCA_QFQ_MAX + 1];
411         struct qfq_aggregate *new_agg = NULL;
412         u32 weight, lmax, inv_w;
413         int err;
414         int delta_w;
415 
416         if (tca[TCA_OPTIONS] == NULL) {
417                 pr_notice("qfq: no options\n");
418                 return -EINVAL;
419         }
420 
421         err = nla_parse_nested(tb, TCA_QFQ_MAX, tca[TCA_OPTIONS], qfq_policy);
422         if (err < 0)
423                 return err;
424 
425         if (tb[TCA_QFQ_WEIGHT]) {
426                 weight = nla_get_u32(tb[TCA_QFQ_WEIGHT]);
427                 if (!weight || weight > (1UL << QFQ_MAX_WSHIFT)) {
428                         pr_notice("qfq: invalid weight %u\n", weight);
429                         return -EINVAL;
430                 }
431         } else
432                 weight = 1;
433 
434         if (tb[TCA_QFQ_LMAX]) {
435                 lmax = nla_get_u32(tb[TCA_QFQ_LMAX]);
436                 if (lmax < QFQ_MIN_LMAX || lmax > (1UL << QFQ_MTU_SHIFT)) {
437                         pr_notice("qfq: invalid max length %u\n", lmax);
438                         return -EINVAL;
439                 }
440         } else
441                 lmax = psched_mtu(qdisc_dev(sch));
442 
443         inv_w = ONE_FP / weight;
444         weight = ONE_FP / inv_w;
445 
446         if (cl != NULL &&
447             lmax == cl->agg->lmax &&
448             weight == cl->agg->class_weight)
449                 return 0; /* nothing to change */
450 
451         delta_w = weight - (cl ? cl->agg->class_weight : 0);
452 
453         if (q->wsum + delta_w > QFQ_MAX_WSUM) {
454                 pr_notice("qfq: total weight out of range (%d + %u)\n",
455                           delta_w, q->wsum);
456                 return -EINVAL;
457         }
458 
459         if (cl != NULL) { /* modify existing class */
460                 if (tca[TCA_RATE]) {
461                         err = gen_replace_estimator(&cl->bstats, NULL,
462                                                     &cl->rate_est,
463                                                     NULL,
464                                                     qdisc_root_sleeping_running(sch),
465                                                     tca[TCA_RATE]);
466                         if (err)
467                                 return err;
468                 }
469                 existing = true;
470                 goto set_change_agg;
471         }
472 
473         /* create and init new class */
474         cl = kzalloc(sizeof(struct qfq_class), GFP_KERNEL);
475         if (cl == NULL)
476                 return -ENOBUFS;
477 
478         cl->refcnt = 1;
479         cl->common.classid = classid;
480         cl->deficit = lmax;
481 
482         cl->qdisc = qdisc_create_dflt(sch->dev_queue,
483                                       &pfifo_qdisc_ops, classid);
484         if (cl->qdisc == NULL)
485                 cl->qdisc = &noop_qdisc;
486 
487         if (tca[TCA_RATE]) {
488                 err = gen_new_estimator(&cl->bstats, NULL,
489                                         &cl->rate_est,
490                                         NULL,
491                                         qdisc_root_sleeping_running(sch),
492                                         tca[TCA_RATE]);
493                 if (err)
494                         goto destroy_class;
495         }
496 
497         sch_tree_lock(sch);
498         qdisc_class_hash_insert(&q->clhash, &cl->common);
499         sch_tree_unlock(sch);
500 
501         qdisc_class_hash_grow(sch, &q->clhash);
502 
503 set_change_agg:
504         sch_tree_lock(sch);
505         new_agg = qfq_find_agg(q, lmax, weight);
506         if (new_agg == NULL) { /* create new aggregate */
507                 sch_tree_unlock(sch);
508                 new_agg = kzalloc(sizeof(*new_agg), GFP_KERNEL);
509                 if (new_agg == NULL) {
510                         err = -ENOBUFS;
511                         gen_kill_estimator(&cl->bstats, &cl->rate_est);
512                         goto destroy_class;
513                 }
514                 sch_tree_lock(sch);
515                 qfq_init_agg(q, new_agg, lmax, weight);
516         }
517         if (existing)
518                 qfq_deact_rm_from_agg(q, cl);
519         qfq_add_to_agg(q, new_agg, cl);
520         sch_tree_unlock(sch);
521 
522         *arg = (unsigned long)cl;
523         return 0;
524 
525 destroy_class:
526         qdisc_destroy(cl->qdisc);
527         kfree(cl);
528         return err;
529 }
530 
531 static void qfq_destroy_class(struct Qdisc *sch, struct qfq_class *cl)
532 {
533         struct qfq_sched *q = qdisc_priv(sch);
534 
535         qfq_rm_from_agg(q, cl);
536         gen_kill_estimator(&cl->bstats, &cl->rate_est);
537         qdisc_destroy(cl->qdisc);
538         kfree(cl);
539 }
540 
541 static int qfq_delete_class(struct Qdisc *sch, unsigned long arg)
542 {
543         struct qfq_sched *q = qdisc_priv(sch);
544         struct qfq_class *cl = (struct qfq_class *)arg;
545 
546         if (cl->filter_cnt > 0)
547                 return -EBUSY;
548 
549         sch_tree_lock(sch);
550 
551         qfq_purge_queue(cl);
552         qdisc_class_hash_remove(&q->clhash, &cl->common);
553 
554         BUG_ON(--cl->refcnt == 0);
555         /*
556          * This shouldn't happen: we "hold" one cops->get() when called
557          * from tc_ctl_tclass; the destroy method is done from cops->put().
558          */
559 
560         sch_tree_unlock(sch);
561         return 0;
562 }
563 
564 static unsigned long qfq_get_class(struct Qdisc *sch, u32 classid)
565 {
566         struct qfq_class *cl = qfq_find_class(sch, classid);
567 
568         if (cl != NULL)
569                 cl->refcnt++;
570 
571         return (unsigned long)cl;
572 }
573 
574 static void qfq_put_class(struct Qdisc *sch, unsigned long arg)
575 {
576         struct qfq_class *cl = (struct qfq_class *)arg;
577 
578         if (--cl->refcnt == 0)
579                 qfq_destroy_class(sch, cl);
580 }
581 
582 static struct tcf_proto __rcu **qfq_tcf_chain(struct Qdisc *sch,
583                                               unsigned long cl)
584 {
585         struct qfq_sched *q = qdisc_priv(sch);
586 
587         if (cl)
588                 return NULL;
589 
590         return &q->filter_list;
591 }
592 
593 static unsigned long qfq_bind_tcf(struct Qdisc *sch, unsigned long parent,
594                                   u32 classid)
595 {
596         struct qfq_class *cl = qfq_find_class(sch, classid);
597 
598         if (cl != NULL)
599                 cl->filter_cnt++;
600 
601         return (unsigned long)cl;
602 }
603 
604 static void qfq_unbind_tcf(struct Qdisc *sch, unsigned long arg)
605 {
606         struct qfq_class *cl = (struct qfq_class *)arg;
607 
608         cl->filter_cnt--;
609 }
610 
611 static int qfq_graft_class(struct Qdisc *sch, unsigned long arg,
612                            struct Qdisc *new, struct Qdisc **old)
613 {
614         struct qfq_class *cl = (struct qfq_class *)arg;
615 
616         if (new == NULL) {
617                 new = qdisc_create_dflt(sch->dev_queue,
618                                         &pfifo_qdisc_ops, cl->common.classid);
619                 if (new == NULL)
620                         new = &noop_qdisc;
621         }
622 
623         *old = qdisc_replace(sch, new, &cl->qdisc);
624         return 0;
625 }
626 
627 static struct Qdisc *qfq_class_leaf(struct Qdisc *sch, unsigned long arg)
628 {
629         struct qfq_class *cl = (struct qfq_class *)arg;
630 
631         return cl->qdisc;
632 }
633 
634 static int qfq_dump_class(struct Qdisc *sch, unsigned long arg,
635                           struct sk_buff *skb, struct tcmsg *tcm)
636 {
637         struct qfq_class *cl = (struct qfq_class *)arg;
638         struct nlattr *nest;
639 
640         tcm->tcm_parent = TC_H_ROOT;
641         tcm->tcm_handle = cl->common.classid;
642         tcm->tcm_info   = cl->qdisc->handle;
643 
644         nest = nla_nest_start(skb, TCA_OPTIONS);
645         if (nest == NULL)
646                 goto nla_put_failure;
647         if (nla_put_u32(skb, TCA_QFQ_WEIGHT, cl->agg->class_weight) ||
648             nla_put_u32(skb, TCA_QFQ_LMAX, cl->agg->lmax))
649                 goto nla_put_failure;
650         return nla_nest_end(skb, nest);
651 
652 nla_put_failure:
653         nla_nest_cancel(skb, nest);
654         return -EMSGSIZE;
655 }
656 
657 static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg,
658                                 struct gnet_dump *d)
659 {
660         struct qfq_class *cl = (struct qfq_class *)arg;
661         struct tc_qfq_stats xstats;
662 
663         memset(&xstats, 0, sizeof(xstats));
664 
665         xstats.weight = cl->agg->class_weight;
666         xstats.lmax = cl->agg->lmax;
667 
668         if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
669                                   d, NULL, &cl->bstats) < 0 ||
670             gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 ||
671             gnet_stats_copy_queue(d, NULL,
672                                   &cl->qdisc->qstats, cl->qdisc->q.qlen) < 0)
673                 return -1;
674 
675         return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
676 }
677 
678 static void qfq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
679 {
680         struct qfq_sched *q = qdisc_priv(sch);
681         struct qfq_class *cl;
682         unsigned int i;
683 
684         if (arg->stop)
685                 return;
686 
687         for (i = 0; i < q->clhash.hashsize; i++) {
688                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
689                         if (arg->count < arg->skip) {
690                                 arg->count++;
691                                 continue;
692                         }
693                         if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
694                                 arg->stop = 1;
695                                 return;
696                         }
697                         arg->count++;
698                 }
699         }
700 }
701 
702 static struct qfq_class *qfq_classify(struct sk_buff *skb, struct Qdisc *sch,
703                                       int *qerr)
704 {
705         struct qfq_sched *q = qdisc_priv(sch);
706         struct qfq_class *cl;
707         struct tcf_result res;
708         struct tcf_proto *fl;
709         int result;
710 
711         if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
712                 pr_debug("qfq_classify: found %d\n", skb->priority);
713                 cl = qfq_find_class(sch, skb->priority);
714                 if (cl != NULL)
715                         return cl;
716         }
717 
718         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
719         fl = rcu_dereference_bh(q->filter_list);
720         result = tc_classify(skb, fl, &res, false);
721         if (result >= 0) {
722 #ifdef CONFIG_NET_CLS_ACT
723                 switch (result) {
724                 case TC_ACT_QUEUED:
725                 case TC_ACT_STOLEN:
726                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
727                 case TC_ACT_SHOT:
728                         return NULL;
729                 }
730 #endif
731                 cl = (struct qfq_class *)res.class;
732                 if (cl == NULL)
733                         cl = qfq_find_class(sch, res.classid);
734                 return cl;
735         }
736 
737         return NULL;
738 }
739 
740 /* Generic comparison function, handling wraparound. */
741 static inline int qfq_gt(u64 a, u64 b)
742 {
743         return (s64)(a - b) > 0;
744 }
745 
746 /* Round a precise timestamp to its slotted value. */
747 static inline u64 qfq_round_down(u64 ts, unsigned int shift)
748 {
749         return ts & ~((1ULL << shift) - 1);
750 }
751 
752 /* return the pointer to the group with lowest index in the bitmap */
753 static inline struct qfq_group *qfq_ffs(struct qfq_sched *q,
754                                         unsigned long bitmap)
755 {
756         int index = __ffs(bitmap);
757         return &q->groups[index];
758 }
759 /* Calculate a mask to mimic what would be ffs_from(). */
760 static inline unsigned long mask_from(unsigned long bitmap, int from)
761 {
762         return bitmap & ~((1UL << from) - 1);
763 }
764 
765 /*
766  * The state computation relies on ER=0, IR=1, EB=2, IB=3
767  * First compute eligibility comparing grp->S, q->V,
768  * then check if someone is blocking us and possibly add EB
769  */
770 static int qfq_calc_state(struct qfq_sched *q, const struct qfq_group *grp)
771 {
772         /* if S > V we are not eligible */
773         unsigned int state = qfq_gt(grp->S, q->V);
774         unsigned long mask = mask_from(q->bitmaps[ER], grp->index);
775         struct qfq_group *next;
776 
777         if (mask) {
778                 next = qfq_ffs(q, mask);
779                 if (qfq_gt(grp->F, next->F))
780                         state |= EB;
781         }
782 
783         return state;
784 }
785 
786 
787 /*
788  * In principle
789  *      q->bitmaps[dst] |= q->bitmaps[src] & mask;
790  *      q->bitmaps[src] &= ~mask;
791  * but we should make sure that src != dst
792  */
793 static inline void qfq_move_groups(struct qfq_sched *q, unsigned long mask,
794                                    int src, int dst)
795 {
796         q->bitmaps[dst] |= q->bitmaps[src] & mask;
797         q->bitmaps[src] &= ~mask;
798 }
799 
800 static void qfq_unblock_groups(struct qfq_sched *q, int index, u64 old_F)
801 {
802         unsigned long mask = mask_from(q->bitmaps[ER], index + 1);
803         struct qfq_group *next;
804 
805         if (mask) {
806                 next = qfq_ffs(q, mask);
807                 if (!qfq_gt(next->F, old_F))
808                         return;
809         }
810 
811         mask = (1UL << index) - 1;
812         qfq_move_groups(q, mask, EB, ER);
813         qfq_move_groups(q, mask, IB, IR);
814 }
815 
816 /*
817  * perhaps
818  *
819         old_V ^= q->V;
820         old_V >>= q->min_slot_shift;
821         if (old_V) {
822                 ...
823         }
824  *
825  */
826 static void qfq_make_eligible(struct qfq_sched *q)
827 {
828         unsigned long vslot = q->V >> q->min_slot_shift;
829         unsigned long old_vslot = q->oldV >> q->min_slot_shift;
830 
831         if (vslot != old_vslot) {
832                 unsigned long mask;
833                 int last_flip_pos = fls(vslot ^ old_vslot);
834 
835                 if (last_flip_pos > 31) /* higher than the number of groups */
836                         mask = ~0UL;    /* make all groups eligible */
837                 else
838                         mask = (1UL << last_flip_pos) - 1;
839 
840                 qfq_move_groups(q, mask, IR, ER);
841                 qfq_move_groups(q, mask, IB, EB);
842         }
843 }
844 
845 /*
846  * The index of the slot in which the input aggregate agg is to be
847  * inserted must not be higher than QFQ_MAX_SLOTS-2. There is a '-2'
848  * and not a '-1' because the start time of the group may be moved
849  * backward by one slot after the aggregate has been inserted, and
850  * this would cause non-empty slots to be right-shifted by one
851  * position.
852  *
853  * QFQ+ fully satisfies this bound to the slot index if the parameters
854  * of the classes are not changed dynamically, and if QFQ+ never
855  * happens to postpone the service of agg unjustly, i.e., it never
856  * happens that the aggregate becomes backlogged and eligible, or just
857  * eligible, while an aggregate with a higher approximated finish time
858  * is being served. In particular, in this case QFQ+ guarantees that
859  * the timestamps of agg are low enough that the slot index is never
860  * higher than 2. Unfortunately, QFQ+ cannot provide the same
861  * guarantee if it happens to unjustly postpone the service of agg, or
862  * if the parameters of some class are changed.
863  *
864  * As for the first event, i.e., an out-of-order service, the
865  * upper bound to the slot index guaranteed by QFQ+ grows to
866  * 2 +
867  * QFQ_MAX_AGG_CLASSES * ((1<<QFQ_MTU_SHIFT)/QFQ_MIN_LMAX) *
868  * (current_max_weight/current_wsum) <= 2 + 8 * 128 * 1.
869  *
870  * The following function deals with this problem by backward-shifting
871  * the timestamps of agg, if needed, so as to guarantee that the slot
872  * index is never higher than QFQ_MAX_SLOTS-2. This backward-shift may
873  * cause the service of other aggregates to be postponed, yet the
874  * worst-case guarantees of these aggregates are not violated.  In
875  * fact, in case of no out-of-order service, the timestamps of agg
876  * would have been even lower than they are after the backward shift,
877  * because QFQ+ would have guaranteed a maximum value equal to 2 for
878  * the slot index, and 2 < QFQ_MAX_SLOTS-2. Hence the aggregates whose
879  * service is postponed because of the backward-shift would have
880  * however waited for the service of agg before being served.
881  *
882  * The other event that may cause the slot index to be higher than 2
883  * for agg is a recent change of the parameters of some class. If the
884  * weight of a class is increased or the lmax (max_pkt_size) of the
885  * class is decreased, then a new aggregate with smaller slot size
886  * than the original parent aggregate of the class may happen to be
887  * activated. The activation of this aggregate should be properly
888  * delayed to when the service of the class has finished in the ideal
889  * system tracked by QFQ+. If the activation of the aggregate is not
890  * delayed to this reference time instant, then this aggregate may be
891  * unjustly served before other aggregates waiting for service. This
892  * may cause the above bound to the slot index to be violated for some
893  * of these unlucky aggregates.
894  *
895  * Instead of delaying the activation of the new aggregate, which is
896  * quite complex, the above-discussed capping of the slot index is
897  * used to handle also the consequences of a change of the parameters
898  * of a class.
899  */
900 static void qfq_slot_insert(struct qfq_group *grp, struct qfq_aggregate *agg,
901                             u64 roundedS)
902 {
903         u64 slot = (roundedS - grp->S) >> grp->slot_shift;
904         unsigned int i; /* slot index in the bucket list */
905 
906         if (unlikely(slot > QFQ_MAX_SLOTS - 2)) {
907                 u64 deltaS = roundedS - grp->S -
908                         ((u64)(QFQ_MAX_SLOTS - 2)<<grp->slot_shift);
909                 agg->S -= deltaS;
910                 agg->F -= deltaS;
911                 slot = QFQ_MAX_SLOTS - 2;
912         }
913 
914         i = (grp->front + slot) % QFQ_MAX_SLOTS;
915 
916         hlist_add_head(&agg->next, &grp->slots[i]);
917         __set_bit(slot, &grp->full_slots);
918 }
919 
920 /* Maybe introduce hlist_first_entry?? */
921 static struct qfq_aggregate *qfq_slot_head(struct qfq_group *grp)
922 {
923         return hlist_entry(grp->slots[grp->front].first,
924                            struct qfq_aggregate, next);
925 }
926 
927 /*
928  * remove the entry from the slot
929  */
930 static void qfq_front_slot_remove(struct qfq_group *grp)
931 {
932         struct qfq_aggregate *agg = qfq_slot_head(grp);
933 
934         BUG_ON(!agg);
935         hlist_del(&agg->next);
936         if (hlist_empty(&grp->slots[grp->front]))
937                 __clear_bit(0, &grp->full_slots);
938 }
939 
940 /*
941  * Returns the first aggregate in the first non-empty bucket of the
942  * group. As a side effect, adjusts the bucket list so the first
943  * non-empty bucket is at position 0 in full_slots.
944  */
945 static struct qfq_aggregate *qfq_slot_scan(struct qfq_group *grp)
946 {
947         unsigned int i;
948 
949         pr_debug("qfq slot_scan: grp %u full %#lx\n",
950                  grp->index, grp->full_slots);
951 
952         if (grp->full_slots == 0)
953                 return NULL;
954 
955         i = __ffs(grp->full_slots);  /* zero based */
956         if (i > 0) {
957                 grp->front = (grp->front + i) % QFQ_MAX_SLOTS;
958                 grp->full_slots >>= i;
959         }
960 
961         return qfq_slot_head(grp);
962 }
963 
964 /*
965  * adjust the bucket list. When the start time of a group decreases,
966  * we move the index down (modulo QFQ_MAX_SLOTS) so we don't need to
967  * move the objects. The mask of occupied slots must be shifted
968  * because we use ffs() to find the first non-empty slot.
969  * This covers decreases in the group's start time, but what about
970  * increases of the start time ?
971  * Here too we should make sure that i is less than 32
972  */
973 static void qfq_slot_rotate(struct qfq_group *grp, u64 roundedS)
974 {
975         unsigned int i = (grp->S - roundedS) >> grp->slot_shift;
976 
977         grp->full_slots <<= i;
978         grp->front = (grp->front - i) % QFQ_MAX_SLOTS;
979 }
980 
981 static void qfq_update_eligible(struct qfq_sched *q)
982 {
983         struct qfq_group *grp;
984         unsigned long ineligible;
985 
986         ineligible = q->bitmaps[IR] | q->bitmaps[IB];
987         if (ineligible) {
988                 if (!q->bitmaps[ER]) {
989                         grp = qfq_ffs(q, ineligible);
990                         if (qfq_gt(grp->S, q->V))
991                                 q->V = grp->S;
992                 }
993                 qfq_make_eligible(q);
994         }
995 }
996 
997 /* Dequeue head packet of the head class in the DRR queue of the aggregate. */
998 static void agg_dequeue(struct qfq_aggregate *agg,
999                         struct qfq_class *cl, unsigned int len)
1000 {
1001         qdisc_dequeue_peeked(cl->qdisc);
1002 
1003         cl->deficit -= (int) len;
1004 
1005         if (cl->qdisc->q.qlen == 0) /* no more packets, remove from list */
1006                 list_del(&cl->alist);
1007         else if (cl->deficit < qdisc_pkt_len(cl->qdisc->ops->peek(cl->qdisc))) {
1008                 cl->deficit += agg->lmax;
1009                 list_move_tail(&cl->alist, &agg->active);
1010         }
1011 }
1012 
1013 static inline struct sk_buff *qfq_peek_skb(struct qfq_aggregate *agg,
1014                                            struct qfq_class **cl,
1015                                            unsigned int *len)
1016 {
1017         struct sk_buff *skb;
1018 
1019         *cl = list_first_entry(&agg->active, struct qfq_class, alist);
1020         skb = (*cl)->qdisc->ops->peek((*cl)->qdisc);
1021         if (skb == NULL)
1022                 WARN_ONCE(1, "qfq_dequeue: non-workconserving leaf\n");
1023         else
1024                 *len = qdisc_pkt_len(skb);
1025 
1026         return skb;
1027 }
1028 
1029 /* Update F according to the actual service received by the aggregate. */
1030 static inline void charge_actual_service(struct qfq_aggregate *agg)
1031 {
1032         /* Compute the service received by the aggregate, taking into
1033          * account that, after decreasing the number of classes in
1034          * agg, it may happen that
1035          * agg->initial_budget - agg->budget > agg->bugdetmax
1036          */
1037         u32 service_received = min(agg->budgetmax,
1038                                    agg->initial_budget - agg->budget);
1039 
1040         agg->F = agg->S + (u64)service_received * agg->inv_w;
1041 }
1042 
1043 /* Assign a reasonable start time for a new aggregate in group i.
1044  * Admissible values for \hat(F) are multiples of \sigma_i
1045  * no greater than V+\sigma_i . Larger values mean that
1046  * we had a wraparound so we consider the timestamp to be stale.
1047  *
1048  * If F is not stale and F >= V then we set S = F.
1049  * Otherwise we should assign S = V, but this may violate
1050  * the ordering in EB (see [2]). So, if we have groups in ER,
1051  * set S to the F_j of the first group j which would be blocking us.
1052  * We are guaranteed not to move S backward because
1053  * otherwise our group i would still be blocked.
1054  */
1055 static void qfq_update_start(struct qfq_sched *q, struct qfq_aggregate *agg)
1056 {
1057         unsigned long mask;
1058         u64 limit, roundedF;
1059         int slot_shift = agg->grp->slot_shift;
1060 
1061         roundedF = qfq_round_down(agg->F, slot_shift);
1062         limit = qfq_round_down(q->V, slot_shift) + (1ULL << slot_shift);
1063 
1064         if (!qfq_gt(agg->F, q->V) || qfq_gt(roundedF, limit)) {
1065                 /* timestamp was stale */
1066                 mask = mask_from(q->bitmaps[ER], agg->grp->index);
1067                 if (mask) {
1068                         struct qfq_group *next = qfq_ffs(q, mask);
1069                         if (qfq_gt(roundedF, next->F)) {
1070                                 if (qfq_gt(limit, next->F))
1071                                         agg->S = next->F;
1072                                 else /* preserve timestamp correctness */
1073                                         agg->S = limit;
1074                                 return;
1075                         }
1076                 }
1077                 agg->S = q->V;
1078         } else  /* timestamp is not stale */
1079                 agg->S = agg->F;
1080 }
1081 
1082 /* Update the timestamps of agg before scheduling/rescheduling it for
1083  * service.  In particular, assign to agg->F its maximum possible
1084  * value, i.e., the virtual finish time with which the aggregate
1085  * should be labeled if it used all its budget once in service.
1086  */
1087 static inline void
1088 qfq_update_agg_ts(struct qfq_sched *q,
1089                     struct qfq_aggregate *agg, enum update_reason reason)
1090 {
1091         if (reason != requeue)
1092                 qfq_update_start(q, agg);
1093         else /* just charge agg for the service received */
1094                 agg->S = agg->F;
1095 
1096         agg->F = agg->S + (u64)agg->budgetmax * agg->inv_w;
1097 }
1098 
1099 static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg);
1100 
1101 static struct sk_buff *qfq_dequeue(struct Qdisc *sch)
1102 {
1103         struct qfq_sched *q = qdisc_priv(sch);
1104         struct qfq_aggregate *in_serv_agg = q->in_serv_agg;
1105         struct qfq_class *cl;
1106         struct sk_buff *skb = NULL;
1107         /* next-packet len, 0 means no more active classes in in-service agg */
1108         unsigned int len = 0;
1109 
1110         if (in_serv_agg == NULL)
1111                 return NULL;
1112 
1113         if (!list_empty(&in_serv_agg->active))
1114                 skb = qfq_peek_skb(in_serv_agg, &cl, &len);
1115 
1116         /*
1117          * If there are no active classes in the in-service aggregate,
1118          * or if the aggregate has not enough budget to serve its next
1119          * class, then choose the next aggregate to serve.
1120          */
1121         if (len == 0 || in_serv_agg->budget < len) {
1122                 charge_actual_service(in_serv_agg);
1123 
1124                 /* recharge the budget of the aggregate */
1125                 in_serv_agg->initial_budget = in_serv_agg->budget =
1126                         in_serv_agg->budgetmax;
1127 
1128                 if (!list_empty(&in_serv_agg->active)) {
1129                         /*
1130                          * Still active: reschedule for
1131                          * service. Possible optimization: if no other
1132                          * aggregate is active, then there is no point
1133                          * in rescheduling this aggregate, and we can
1134                          * just keep it as the in-service one. This
1135                          * should be however a corner case, and to
1136                          * handle it, we would need to maintain an
1137                          * extra num_active_aggs field.
1138                         */
1139                         qfq_update_agg_ts(q, in_serv_agg, requeue);
1140                         qfq_schedule_agg(q, in_serv_agg);
1141                 } else if (sch->q.qlen == 0) { /* no aggregate to serve */
1142                         q->in_serv_agg = NULL;
1143                         return NULL;
1144                 }
1145 
1146                 /*
1147                  * If we get here, there are other aggregates queued:
1148                  * choose the new aggregate to serve.
1149                  */
1150                 in_serv_agg = q->in_serv_agg = qfq_choose_next_agg(q);
1151                 skb = qfq_peek_skb(in_serv_agg, &cl, &len);
1152         }
1153         if (!skb)
1154                 return NULL;
1155 
1156         qdisc_qstats_backlog_dec(sch, skb);
1157         sch->q.qlen--;
1158         qdisc_bstats_update(sch, skb);
1159 
1160         agg_dequeue(in_serv_agg, cl, len);
1161         /* If lmax is lowered, through qfq_change_class, for a class
1162          * owning pending packets with larger size than the new value
1163          * of lmax, then the following condition may hold.
1164          */
1165         if (unlikely(in_serv_agg->budget < len))
1166                 in_serv_agg->budget = 0;
1167         else
1168                 in_serv_agg->budget -= len;
1169 
1170         q->V += (u64)len * q->iwsum;
1171         pr_debug("qfq dequeue: len %u F %lld now %lld\n",
1172                  len, (unsigned long long) in_serv_agg->F,
1173                  (unsigned long long) q->V);
1174 
1175         return skb;
1176 }
1177 
1178 static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *q)
1179 {
1180         struct qfq_group *grp;
1181         struct qfq_aggregate *agg, *new_front_agg;
1182         u64 old_F;
1183 
1184         qfq_update_eligible(q);
1185         q->oldV = q->V;
1186 
1187         if (!q->bitmaps[ER])
1188                 return NULL;
1189 
1190         grp = qfq_ffs(q, q->bitmaps[ER]);
1191         old_F = grp->F;
1192 
1193         agg = qfq_slot_head(grp);
1194 
1195         /* agg starts to be served, remove it from schedule */
1196         qfq_front_slot_remove(grp);
1197 
1198         new_front_agg = qfq_slot_scan(grp);
1199 
1200         if (new_front_agg == NULL) /* group is now inactive, remove from ER */
1201                 __clear_bit(grp->index, &q->bitmaps[ER]);
1202         else {
1203                 u64 roundedS = qfq_round_down(new_front_agg->S,
1204                                               grp->slot_shift);
1205                 unsigned int s;
1206 
1207                 if (grp->S == roundedS)
1208                         return agg;
1209                 grp->S = roundedS;
1210                 grp->F = roundedS + (2ULL << grp->slot_shift);
1211                 __clear_bit(grp->index, &q->bitmaps[ER]);
1212                 s = qfq_calc_state(q, grp);
1213                 __set_bit(grp->index, &q->bitmaps[s]);
1214         }
1215 
1216         qfq_unblock_groups(q, grp->index, old_F);
1217 
1218         return agg;
1219 }
1220 
1221 static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
1222                        struct sk_buff **to_free)
1223 {
1224         struct qfq_sched *q = qdisc_priv(sch);
1225         struct qfq_class *cl;
1226         struct qfq_aggregate *agg;
1227         int err = 0;
1228 
1229         cl = qfq_classify(skb, sch, &err);
1230         if (cl == NULL) {
1231                 if (err & __NET_XMIT_BYPASS)
1232                         qdisc_qstats_drop(sch);
1233                 kfree_skb(skb);
1234                 return err;
1235         }
1236         pr_debug("qfq_enqueue: cl = %x\n", cl->common.classid);
1237 
1238         if (unlikely(cl->agg->lmax < qdisc_pkt_len(skb))) {
1239                 pr_debug("qfq: increasing maxpkt from %u to %u for class %u",
1240                          cl->agg->lmax, qdisc_pkt_len(skb), cl->common.classid);
1241                 err = qfq_change_agg(sch, cl, cl->agg->class_weight,
1242                                      qdisc_pkt_len(skb));
1243                 if (err) {
1244                         cl->qstats.drops++;
1245                         return qdisc_drop(skb, sch, to_free);
1246                 }
1247         }
1248 
1249         err = qdisc_enqueue(skb, cl->qdisc, to_free);
1250         if (unlikely(err != NET_XMIT_SUCCESS)) {
1251                 pr_debug("qfq_enqueue: enqueue failed %d\n", err);
1252                 if (net_xmit_drop_count(err)) {
1253                         cl->qstats.drops++;
1254                         qdisc_qstats_drop(sch);
1255                 }
1256                 return err;
1257         }
1258 
1259         bstats_update(&cl->bstats, skb);
1260         qdisc_qstats_backlog_inc(sch, skb);
1261         ++sch->q.qlen;
1262 
1263         agg = cl->agg;
1264         /* if the queue was not empty, then done here */
1265         if (cl->qdisc->q.qlen != 1) {
1266                 if (unlikely(skb == cl->qdisc->ops->peek(cl->qdisc)) &&
1267                     list_first_entry(&agg->active, struct qfq_class, alist)
1268                     == cl && cl->deficit < qdisc_pkt_len(skb))
1269                         list_move_tail(&cl->alist, &agg->active);
1270 
1271                 return err;
1272         }
1273 
1274         /* schedule class for service within the aggregate */
1275         cl->deficit = agg->lmax;
1276         list_add_tail(&cl->alist, &agg->active);
1277 
1278         if (list_first_entry(&agg->active, struct qfq_class, alist) != cl ||
1279             q->in_serv_agg == agg)
1280                 return err; /* non-empty or in service, nothing else to do */
1281 
1282         qfq_activate_agg(q, agg, enqueue);
1283 
1284         return err;
1285 }
1286 
1287 /*
1288  * Schedule aggregate according to its timestamps.
1289  */
1290 static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
1291 {
1292         struct qfq_group *grp = agg->grp;
1293         u64 roundedS;
1294         int s;
1295 
1296         roundedS = qfq_round_down(agg->S, grp->slot_shift);
1297 
1298         /*
1299          * Insert agg in the correct bucket.
1300          * If agg->S >= grp->S we don't need to adjust the
1301          * bucket list and simply go to the insertion phase.
1302          * Otherwise grp->S is decreasing, we must make room
1303          * in the bucket list, and also recompute the group state.
1304          * Finally, if there were no flows in this group and nobody
1305          * was in ER make sure to adjust V.
1306          */
1307         if (grp->full_slots) {
1308                 if (!qfq_gt(grp->S, agg->S))
1309                         goto skip_update;
1310 
1311                 /* create a slot for this agg->S */
1312                 qfq_slot_rotate(grp, roundedS);
1313                 /* group was surely ineligible, remove */
1314                 __clear_bit(grp->index, &q->bitmaps[IR]);
1315                 __clear_bit(grp->index, &q->bitmaps[IB]);
1316         } else if (!q->bitmaps[ER] && qfq_gt(roundedS, q->V) &&
1317                    q->in_serv_agg == NULL)
1318                 q->V = roundedS;
1319 
1320         grp->S = roundedS;
1321         grp->F = roundedS + (2ULL << grp->slot_shift);
1322         s = qfq_calc_state(q, grp);
1323         __set_bit(grp->index, &q->bitmaps[s]);
1324 
1325         pr_debug("qfq enqueue: new state %d %#lx S %lld F %lld V %lld\n",
1326                  s, q->bitmaps[s],
1327                  (unsigned long long) agg->S,
1328                  (unsigned long long) agg->F,
1329                  (unsigned long long) q->V);
1330 
1331 skip_update:
1332         qfq_slot_insert(grp, agg, roundedS);
1333 }
1334 
1335 
1336 /* Update agg ts and schedule agg for service */
1337 static void qfq_activate_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
1338                              enum update_reason reason)
1339 {
1340         agg->initial_budget = agg->budget = agg->budgetmax; /* recharge budg. */
1341 
1342         qfq_update_agg_ts(q, agg, reason);
1343         if (q->in_serv_agg == NULL) { /* no aggr. in service or scheduled */
1344                 q->in_serv_agg = agg; /* start serving this aggregate */
1345                  /* update V: to be in service, agg must be eligible */
1346                 q->oldV = q->V = agg->S;
1347         } else if (agg != q->in_serv_agg)
1348                 qfq_schedule_agg(q, agg);
1349 }
1350 
1351 static void qfq_slot_remove(struct qfq_sched *q, struct qfq_group *grp,
1352                             struct qfq_aggregate *agg)
1353 {
1354         unsigned int i, offset;
1355         u64 roundedS;
1356 
1357         roundedS = qfq_round_down(agg->S, grp->slot_shift);
1358         offset = (roundedS - grp->S) >> grp->slot_shift;
1359 
1360         i = (grp->front + offset) % QFQ_MAX_SLOTS;
1361 
1362         hlist_del(&agg->next);
1363         if (hlist_empty(&grp->slots[i]))
1364                 __clear_bit(offset, &grp->full_slots);
1365 }
1366 
1367 /*
1368  * Called to forcibly deschedule an aggregate.  If the aggregate is
1369  * not in the front bucket, or if the latter has other aggregates in
1370  * the front bucket, we can simply remove the aggregate with no other
1371  * side effects.
1372  * Otherwise we must propagate the event up.
1373  */
1374 static void qfq_deactivate_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
1375 {
1376         struct qfq_group *grp = agg->grp;
1377         unsigned long mask;
1378         u64 roundedS;
1379         int s;
1380 
1381         if (agg == q->in_serv_agg) {
1382                 charge_actual_service(agg);
1383                 q->in_serv_agg = qfq_choose_next_agg(q);
1384                 return;
1385         }
1386 
1387         agg->F = agg->S;
1388         qfq_slot_remove(q, grp, agg);
1389 
1390         if (!grp->full_slots) {
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 
1395                 if (test_bit(grp->index, &q->bitmaps[ER]) &&
1396                     !(q->bitmaps[ER] & ~((1UL << grp->index) - 1))) {
1397                         mask = q->bitmaps[ER] & ((1UL << grp->index) - 1);
1398                         if (mask)
1399                                 mask = ~((1UL << __fls(mask)) - 1);
1400                         else
1401                                 mask = ~0UL;
1402                         qfq_move_groups(q, mask, EB, ER);
1403                         qfq_move_groups(q, mask, IB, IR);
1404                 }
1405                 __clear_bit(grp->index, &q->bitmaps[ER]);
1406         } else if (hlist_empty(&grp->slots[grp->front])) {
1407                 agg = qfq_slot_scan(grp);
1408                 roundedS = qfq_round_down(agg->S, grp->slot_shift);
1409                 if (grp->S != roundedS) {
1410                         __clear_bit(grp->index, &q->bitmaps[ER]);
1411                         __clear_bit(grp->index, &q->bitmaps[IR]);
1412                         __clear_bit(grp->index, &q->bitmaps[EB]);
1413                         __clear_bit(grp->index, &q->bitmaps[IB]);
1414                         grp->S = roundedS;
1415                         grp->F = roundedS + (2ULL << grp->slot_shift);
1416                         s = qfq_calc_state(q, grp);
1417                         __set_bit(grp->index, &q->bitmaps[s]);
1418                 }
1419         }
1420 }
1421 
1422 static void qfq_qlen_notify(struct Qdisc *sch, unsigned long arg)
1423 {
1424         struct qfq_sched *q = qdisc_priv(sch);
1425         struct qfq_class *cl = (struct qfq_class *)arg;
1426 
1427         if (cl->qdisc->q.qlen == 0)
1428                 qfq_deactivate_class(q, cl);
1429 }
1430 
1431 static int qfq_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
1432 {
1433         struct qfq_sched *q = qdisc_priv(sch);
1434         struct qfq_group *grp;
1435         int i, j, err;
1436         u32 max_cl_shift, maxbudg_shift, max_classes;
1437 
1438         err = qdisc_class_hash_init(&q->clhash);
1439         if (err < 0)
1440                 return err;
1441 
1442         if (qdisc_dev(sch)->tx_queue_len + 1 > QFQ_MAX_AGG_CLASSES)
1443                 max_classes = QFQ_MAX_AGG_CLASSES;
1444         else
1445                 max_classes = qdisc_dev(sch)->tx_queue_len + 1;
1446         /* max_cl_shift = floor(log_2(max_classes)) */
1447         max_cl_shift = __fls(max_classes);
1448         q->max_agg_classes = 1<<max_cl_shift;
1449 
1450         /* maxbudg_shift = log2(max_len * max_classes_per_agg) */
1451         maxbudg_shift = QFQ_MTU_SHIFT + max_cl_shift;
1452         q->min_slot_shift = FRAC_BITS + maxbudg_shift - QFQ_MAX_INDEX;
1453 
1454         for (i = 0; i <= QFQ_MAX_INDEX; i++) {
1455                 grp = &q->groups[i];
1456                 grp->index = i;
1457                 grp->slot_shift = q->min_slot_shift + i;
1458                 for (j = 0; j < QFQ_MAX_SLOTS; j++)
1459                         INIT_HLIST_HEAD(&grp->slots[j]);
1460         }
1461 
1462         INIT_HLIST_HEAD(&q->nonfull_aggs);
1463 
1464         return 0;
1465 }
1466 
1467 static void qfq_reset_qdisc(struct Qdisc *sch)
1468 {
1469         struct qfq_sched *q = qdisc_priv(sch);
1470         struct qfq_class *cl;
1471         unsigned int i;
1472 
1473         for (i = 0; i < q->clhash.hashsize; i++) {
1474                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
1475                         if (cl->qdisc->q.qlen > 0)
1476                                 qfq_deactivate_class(q, cl);
1477 
1478                         qdisc_reset(cl->qdisc);
1479                 }
1480         }
1481         sch->qstats.backlog = 0;
1482         sch->q.qlen = 0;
1483 }
1484 
1485 static void qfq_destroy_qdisc(struct Qdisc *sch)
1486 {
1487         struct qfq_sched *q = qdisc_priv(sch);
1488         struct qfq_class *cl;
1489         struct hlist_node *next;
1490         unsigned int i;
1491 
1492         tcf_destroy_chain(&q->filter_list);
1493 
1494         for (i = 0; i < q->clhash.hashsize; i++) {
1495                 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],
1496                                           common.hnode) {
1497                         qfq_destroy_class(sch, cl);
1498                 }
1499         }
1500         qdisc_class_hash_destroy(&q->clhash);
1501 }
1502 
1503 static const struct Qdisc_class_ops qfq_class_ops = {
1504         .change         = qfq_change_class,
1505         .delete         = qfq_delete_class,
1506         .get            = qfq_get_class,
1507         .put            = qfq_put_class,
1508         .tcf_chain      = qfq_tcf_chain,
1509         .bind_tcf       = qfq_bind_tcf,
1510         .unbind_tcf     = qfq_unbind_tcf,
1511         .graft          = qfq_graft_class,
1512         .leaf           = qfq_class_leaf,
1513         .qlen_notify    = qfq_qlen_notify,
1514         .dump           = qfq_dump_class,
1515         .dump_stats     = qfq_dump_class_stats,
1516         .walk           = qfq_walk,
1517 };
1518 
1519 static struct Qdisc_ops qfq_qdisc_ops __read_mostly = {
1520         .cl_ops         = &qfq_class_ops,
1521         .id             = "qfq",
1522         .priv_size      = sizeof(struct qfq_sched),
1523         .enqueue        = qfq_enqueue,
1524         .dequeue        = qfq_dequeue,
1525         .peek           = qdisc_peek_dequeued,
1526         .init           = qfq_init_qdisc,
1527         .reset          = qfq_reset_qdisc,
1528         .destroy        = qfq_destroy_qdisc,
1529         .owner          = THIS_MODULE,
1530 };
1531 
1532 static int __init qfq_init(void)
1533 {
1534         return register_qdisc(&qfq_qdisc_ops);
1535 }
1536 
1537 static void __exit qfq_exit(void)
1538 {
1539         unregister_qdisc(&qfq_qdisc_ops);
1540 }
1541 
1542 module_init(qfq_init);
1543 module_exit(qfq_exit);
1544 MODULE_LICENSE("GPL");
1545 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp