1// SPDX-License-Identifier: GPL-2.0-only 2/* 3 * net/sched/sch_qfq.c Quick Fair Queueing Plus Scheduler. 4 * 5 * Copyright (c) 2009 Fabio Checconi, Luigi Rizzo, and Paolo Valente. 6 * Copyright (c) 2012 Paolo Valente. 7 */ 8 9#include <linux/module.h> 10#include <linux/init.h> 11#include <linux/bitops.h> 12#include <linux/errno.h> 13#include <linux/netdevice.h> 14#include <linux/pkt_sched.h> 15#include <net/sch_generic.h> 16#include <net/pkt_sched.h> 17#include <net/pkt_cls.h> 18 19 20/* Quick Fair Queueing Plus 21 ======================== 22 23 Sources: 24 25 [1] Paolo Valente, 26 "Reducing the Execution Time of Fair-Queueing Schedulers." 27 http://algo.ing.unimo.it/people/paolo/agg-sched/agg-sched.pdf 28 29 Sources for QFQ: 30 31 [2] Fabio Checconi, Luigi Rizzo, and Paolo Valente: "QFQ: Efficient 32 Packet Scheduling with Tight Bandwidth Distribution Guarantees." 33 34 See also: 35 http://retis.sssup.it/~fabio/linux/qfq/ 36 */ 37 38/* 39 40 QFQ+ divides classes into aggregates of at most MAX_AGG_CLASSES 41 classes. Each aggregate is timestamped with a virtual start time S 42 and a virtual finish time F, and scheduled according to its 43 timestamps. S and F are computed as a function of a system virtual 44 time function V. The classes within each aggregate are instead 45 scheduled with DRR. 46 47 To speed up operations, QFQ+ divides also aggregates into a limited 48 number of groups. Which group a class belongs to depends on the 49 ratio between the maximum packet length for the class and the weight 50 of the class. Groups have their own S and F. In the end, QFQ+ 51 schedules groups, then aggregates within groups, then classes within 52 aggregates. See [1] and [2] for a full description. 53 54 Virtual time computations. 55 56 S, F and V are all computed in fixed point arithmetic with 57 FRAC_BITS decimal bits. 58 59 QFQ_MAX_INDEX is the maximum index allowed for a group. We need 60 one bit per index. 61 QFQ_MAX_WSHIFT is the maximum power of two supported as a weight. 62 63 The layout of the bits is as below: 64 65 [ MTU_SHIFT ][ FRAC_BITS ] 66 [ MAX_INDEX ][ MIN_SLOT_SHIFT ] 67 ^.__grp->index = 0 68 *.__grp->slot_shift 69 70 where MIN_SLOT_SHIFT is derived by difference from the others. 71 72 The max group index corresponds to Lmax/w_min, where 73 Lmax=1<<MTU_SHIFT, w_min = 1 . 74 From this, and knowing how many groups (MAX_INDEX) we want, 75 we can derive the shift corresponding to each group. 76 77 Because we often need to compute 78 F = S + len/w_i and V = V + len/wsum 79 instead of storing w_i store the value 80 inv_w = (1<<FRAC_BITS)/w_i 81 so we can do F = S + len * inv_w * wsum. 82 We use W_TOT in the formulas so we can easily move between 83 static and adaptive weight sum. 84 85 The per-scheduler-instance data contain all the data structures 86 for the scheduler: bitmaps and bucket lists. 87 88 */ 89 90/* 91 * Maximum number of consecutive slots occupied by backlogged classes 92 * inside a group. 93 */ 94#define QFQ_MAX_SLOTS 32 95 96/* 97 * Shifts used for aggregate<->group mapping. We allow class weights that are 98 * in the range [1, 2^MAX_WSHIFT], and we try to map each aggregate i to the 99 * group with the smallest index that can support the L_i / r_i configured 100 * for the classes in the aggregate. 101 * 102 * grp->index is the index of the group; and grp->slot_shift 103 * is the shift for the corresponding (scaled) sigma_i. 104 */ 105#define QFQ_MAX_INDEX 24 106#define QFQ_MAX_WSHIFT 10 107 108#define QFQ_MAX_WEIGHT (1<<QFQ_MAX_WSHIFT) /* see qfq_slot_insert */ 109#define QFQ_MAX_WSUM (64*QFQ_MAX_WEIGHT) 110 111#define FRAC_BITS 30 /* fixed point arithmetic */ 112#define ONE_FP (1UL << FRAC_BITS) 113 114#define QFQ_MTU_SHIFT 16 /* to support TSO/GSO */ 115#define QFQ_MIN_LMAX 512 /* see qfq_slot_insert */ 116#define QFQ_MAX_LMAX (1UL << QFQ_MTU_SHIFT) 117 118#define QFQ_MAX_AGG_CLASSES 8 /* max num classes per aggregate allowed */ 119 120/* 121 * Possible group states. These values are used as indexes for the bitmaps 122 * array of struct qfq_queue. 123 */ 124enum qfq_state { ER, IR, EB, IB, QFQ_MAX_STATE }; 125 126struct qfq_group; 127 128struct qfq_aggregate; 129 130struct qfq_class { 131 struct Qdisc_class_common common; 132 133 struct gnet_stats_basic_sync bstats; 134 struct gnet_stats_queue qstats; 135 struct net_rate_estimator __rcu *rate_est; 136 struct Qdisc *qdisc; 137 struct list_head alist; /* Link for active-classes list. */ 138 struct qfq_aggregate *agg; /* Parent aggregate. */ 139 int deficit; /* DRR deficit counter. */ 140}; 141 142struct qfq_aggregate { 143 struct hlist_node next; /* Link for the slot list. */ 144 u64 S, F; /* flow timestamps (exact) */ 145 146 /* group we belong to. In principle we would need the index, 147 * which is log_2(lmax/weight), but we never reference it 148 * directly, only the group. 149 */ 150 struct qfq_group *grp; 151 152 /* these are copied from the flowset. */ 153 u32 class_weight; /* Weight of each class in this aggregate. */ 154 /* Max pkt size for the classes in this aggregate, DRR quantum. */ 155 int lmax; 156 157 u32 inv_w; /* ONE_FP/(sum of weights of classes in aggr.). */ 158 u32 budgetmax; /* Max budget for this aggregate. */ 159 u32 initial_budget, budget; /* Initial and current budget. */ 160 161 int num_classes; /* Number of classes in this aggr. */ 162 struct list_head active; /* DRR queue of active classes. */ 163 164 struct hlist_node nonfull_next; /* See nonfull_aggs in qfq_sched. */ 165}; 166 167struct qfq_group { 168 u64 S, F; /* group timestamps (approx). */ 169 unsigned int slot_shift; /* Slot shift. */ 170 unsigned int index; /* Group index. */ 171 unsigned int front; /* Index of the front slot. */ 172 unsigned long full_slots; /* non-empty slots */ 173 174 /* Array of RR lists of active aggregates. */ 175 struct hlist_head slots[QFQ_MAX_SLOTS]; 176}; 177 178struct qfq_sched { 179 struct tcf_proto __rcu *filter_list; 180 struct tcf_block *block; 181 struct Qdisc_class_hash clhash; 182 183 u64 oldV, V; /* Precise virtual times. */ 184 struct qfq_aggregate *in_serv_agg; /* Aggregate being served. */ 185 u32 wsum; /* weight sum */ 186 u32 iwsum; /* inverse weight sum */ 187 188 unsigned long bitmaps[QFQ_MAX_STATE]; /* Group bitmaps. */ 189 struct qfq_group groups[QFQ_MAX_INDEX + 1]; /* The groups. */ 190 u32 min_slot_shift; /* Index of the group-0 bit in the bitmaps. */ 191 192 u32 max_agg_classes; /* Max number of classes per aggr. */ 193 struct hlist_head nonfull_aggs; /* Aggs with room for more classes. */ 194}; 195 196/* 197 * Possible reasons why the timestamps of an aggregate are updated 198 * enqueue: the aggregate switches from idle to active and must scheduled 199 * for service 200 * requeue: the aggregate finishes its budget, so it stops being served and 201 * must be rescheduled for service 202 */ 203enum update_reason {enqueue, requeue}; 204 205static struct qfq_class *qfq_find_class(struct Qdisc *sch, u32 classid) 206{ 207 struct qfq_sched *q = qdisc_priv(sch); 208 struct Qdisc_class_common *clc; 209 210 clc = qdisc_class_find(&q->clhash, classid); 211 if (clc == NULL) 212 return NULL; 213 return container_of(clc, struct qfq_class, common); 214} 215 216static const struct netlink_range_validation lmax_range = { 217 .min = QFQ_MIN_LMAX, 218 .max = QFQ_MAX_LMAX, 219}; 220 221static const struct nla_policy qfq_policy[TCA_QFQ_MAX + 1] = { 222 [TCA_QFQ_WEIGHT] = NLA_POLICY_RANGE(NLA_U32, 1, QFQ_MAX_WEIGHT), 223 [TCA_QFQ_LMAX] = NLA_POLICY_FULL_RANGE(NLA_U32, &lmax_range), 224}; 225 226/* 227 * Calculate a flow index, given its weight and maximum packet length. 228 * index = log_2(maxlen/weight) but we need to apply the scaling. 229 * This is used only once at flow creation. 230 */ 231static int qfq_calc_index(u32 inv_w, unsigned int maxlen, u32 min_slot_shift) 232{ 233 u64 slot_size = (u64)maxlen * inv_w; 234 unsigned long size_map; 235 int index = 0; 236 237 size_map = slot_size >> min_slot_shift; 238 if (!size_map) 239 goto out; 240 241 index = __fls(size_map) + 1; /* basically a log_2 */ 242 index -= !(slot_size - (1ULL << (index + min_slot_shift - 1))); 243 244 if (index < 0) 245 index = 0; 246out: 247 pr_debug("qfq calc_index: W = %lu, L = %u, I = %d\n", 248 (unsigned long) ONE_FP/inv_w, maxlen, index); 249 250 return index; 251} 252 253static void qfq_deactivate_agg(struct qfq_sched *, struct qfq_aggregate *); 254static void qfq_activate_agg(struct qfq_sched *, struct qfq_aggregate *, 255 enum update_reason); 256 257static void qfq_init_agg(struct qfq_sched *q, struct qfq_aggregate *agg, 258 u32 lmax, u32 weight) 259{ 260 INIT_LIST_HEAD(&agg->active); 261 hlist_add_head(&agg->nonfull_next, &q->nonfull_aggs); 262 263 agg->lmax = lmax; 264 agg->class_weight = weight; 265} 266 267static struct qfq_aggregate *qfq_find_agg(struct qfq_sched *q, 268 u32 lmax, u32 weight) 269{ 270 struct qfq_aggregate *agg; 271 272 hlist_for_each_entry(agg, &q->nonfull_aggs, nonfull_next) 273 if (agg->lmax == lmax && agg->class_weight == weight) 274 return agg; 275 276 return NULL; 277} 278 279 280/* Update aggregate as a function of the new number of classes. */ 281static void qfq_update_agg(struct qfq_sched *q, struct qfq_aggregate *agg, 282 int new_num_classes) 283{ 284 u32 new_agg_weight; 285 286 if (new_num_classes == q->max_agg_classes) 287 hlist_del_init(&agg->nonfull_next); 288 289 if (agg->num_classes > new_num_classes && 290 new_num_classes == q->max_agg_classes - 1) /* agg no more full */ 291 hlist_add_head(&agg->nonfull_next, &q->nonfull_aggs); 292 293 /* The next assignment may let 294 * agg->initial_budget > agg->budgetmax 295 * hold, we will take it into account in charge_actual_service(). 296 */ 297 agg->budgetmax = new_num_classes * agg->lmax; 298 new_agg_weight = agg->class_weight * new_num_classes; 299 agg->inv_w = ONE_FP/new_agg_weight; 300 301 if (agg->grp == NULL) { 302 int i = qfq_calc_index(agg->inv_w, agg->budgetmax, 303 q->min_slot_shift); 304 agg->grp = &q->groups[i]; 305 } 306 307 q->wsum += 308 (int) agg->class_weight * (new_num_classes - agg->num_classes); 309 q->iwsum = ONE_FP / q->wsum; 310 311 agg->num_classes = new_num_classes; 312} 313 314/* Add class to aggregate. */ 315static void qfq_add_to_agg(struct qfq_sched *q, 316 struct qfq_aggregate *agg, 317 struct qfq_class *cl) 318{ 319 cl->agg = agg; 320 321 qfq_update_agg(q, agg, agg->num_classes+1); 322 if (cl->qdisc->q.qlen > 0) { /* adding an active class */ 323 list_add_tail(&cl->alist, &agg->active); 324 if (list_first_entry(&agg->active, struct qfq_class, alist) == 325 cl && q->in_serv_agg != agg) /* agg was inactive */ 326 qfq_activate_agg(q, agg, enqueue); /* schedule agg */ 327 } 328} 329 330static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *); 331 332static void qfq_destroy_agg(struct qfq_sched *q, struct qfq_aggregate *agg) 333{ 334 hlist_del_init(&agg->nonfull_next); 335 q->wsum -= agg->class_weight; 336 if (q->wsum != 0) 337 q->iwsum = ONE_FP / q->wsum; 338 339 if (q->in_serv_agg == agg) 340 q->in_serv_agg = qfq_choose_next_agg(q); 341 kfree(agg); 342} 343 344/* Deschedule class from within its parent aggregate. */ 345static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl) 346{ 347 struct qfq_aggregate *agg = cl->agg; 348 349 350 list_del(&cl->alist); /* remove from RR queue of the aggregate */ 351 if (list_empty(&agg->active)) /* agg is now inactive */ 352 qfq_deactivate_agg(q, agg); 353} 354 355/* Remove class from its parent aggregate. */ 356static void qfq_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl) 357{ 358 struct qfq_aggregate *agg = cl->agg; 359 360 cl->agg = NULL; 361 if (agg->num_classes == 1) { /* agg being emptied, destroy it */ 362 qfq_destroy_agg(q, agg); 363 return; 364 } 365 qfq_update_agg(q, agg, agg->num_classes-1); 366} 367 368/* Deschedule class and remove it from its parent aggregate. */ 369static void qfq_deact_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl) 370{ 371 if (cl->qdisc->q.qlen > 0) /* class is active */ 372 qfq_deactivate_class(q, cl); 373 374 qfq_rm_from_agg(q, cl); 375} 376 377/* Move class to a new aggregate, matching the new class weight and/or lmax */ 378static int qfq_change_agg(struct Qdisc *sch, struct qfq_class *cl, u32 weight, 379 u32 lmax) 380{ 381 struct qfq_sched *q = qdisc_priv(sch); 382 struct qfq_aggregate *new_agg; 383 384 /* 'lmax' can range from [QFQ_MIN_LMAX, pktlen + stab overhead] */ 385 if (lmax > QFQ_MAX_LMAX) 386 return -EINVAL; 387 388 new_agg = qfq_find_agg(q, lmax, weight); 389 if (new_agg == NULL) { /* create new aggregate */ 390 new_agg = kzalloc(sizeof(*new_agg), GFP_ATOMIC); 391 if (new_agg == NULL) 392 return -ENOBUFS; 393 qfq_init_agg(q, new_agg, lmax, weight); 394 } 395 qfq_deact_rm_from_agg(q, cl); 396 qfq_add_to_agg(q, new_agg, cl); 397 398 return 0; 399} 400 401static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 402 struct nlattr **tca, unsigned long *arg, 403 struct netlink_ext_ack *extack) 404{ 405 struct qfq_sched *q = qdisc_priv(sch); 406 struct qfq_class *cl = (struct qfq_class *)*arg; 407 bool existing = false; 408 struct nlattr *tb[TCA_QFQ_MAX + 1]; 409 struct qfq_aggregate *new_agg = NULL; 410 u32 weight, lmax, inv_w; 411 int err; 412 int delta_w; 413 414 if (NL_REQ_ATTR_CHECK(extack, NULL, tca, TCA_OPTIONS)) { 415 NL_SET_ERR_MSG_MOD(extack, "missing options"); 416 return -EINVAL; 417 } 418 419 err = nla_parse_nested_deprecated(tb, TCA_QFQ_MAX, tca[TCA_OPTIONS], 420 qfq_policy, extack); 421 if (err < 0) 422 return err; 423 424 if (tb[TCA_QFQ_WEIGHT]) 425 weight = nla_get_u32(tb[TCA_QFQ_WEIGHT]); 426 else 427 weight = 1; 428 429 if (tb[TCA_QFQ_LMAX]) { 430 lmax = nla_get_u32(tb[TCA_QFQ_LMAX]); 431 } else { 432 /* MTU size is user controlled */ 433 lmax = psched_mtu(qdisc_dev(sch)); 434 if (lmax < QFQ_MIN_LMAX || lmax > QFQ_MAX_LMAX) { 435 NL_SET_ERR_MSG_MOD(extack, 436 "MTU size out of bounds for qfq"); 437 return -EINVAL; 438 } 439 } 440 441 inv_w = ONE_FP / weight; 442 weight = ONE_FP / inv_w; 443 444 if (cl != NULL && 445 lmax == cl->agg->lmax && 446 weight == cl->agg->class_weight) 447 return 0; /* nothing to change */ 448 449 delta_w = weight - (cl ? cl->agg->class_weight : 0); 450 451 if (q->wsum + delta_w > QFQ_MAX_WSUM) { 452 NL_SET_ERR_MSG_FMT_MOD(extack, 453 "total weight out of range (%d + %u)\n", 454 delta_w, q->wsum); 455 return -EINVAL; 456 } 457 458 if (cl != NULL) { /* modify existing class */ 459 if (tca[TCA_RATE]) { 460 err = gen_replace_estimator(&cl->bstats, NULL, 461 &cl->rate_est, 462 NULL, 463 true, 464 tca[TCA_RATE]); 465 if (err) 466 return err; 467 } 468 existing = true; 469 goto set_change_agg; 470 } 471 472 /* create and init new class */ 473 cl = kzalloc(sizeof(struct qfq_class), GFP_KERNEL); 474 if (cl == NULL) 475 return -ENOBUFS; 476 477 gnet_stats_basic_sync_init(&cl->bstats); 478 cl->common.classid = classid; 479 cl->deficit = lmax; 480 481 cl->qdisc = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, 482 classid, NULL); 483 if (cl->qdisc == NULL) 484 cl->qdisc = &noop_qdisc; 485 486 if (tca[TCA_RATE]) { 487 err = gen_new_estimator(&cl->bstats, NULL, 488 &cl->rate_est, 489 NULL, 490 true, 491 tca[TCA_RATE]); 492 if (err) 493 goto destroy_class; 494 } 495 496 if (cl->qdisc != &noop_qdisc) 497 qdisc_hash_add(cl->qdisc, true); 498 499set_change_agg: 500 sch_tree_lock(sch); 501 new_agg = qfq_find_agg(q, lmax, weight); 502 if (new_agg == NULL) { /* create new aggregate */ 503 sch_tree_unlock(sch); 504 new_agg = kzalloc(sizeof(*new_agg), GFP_KERNEL); 505 if (new_agg == NULL) { 506 err = -ENOBUFS; 507 gen_kill_estimator(&cl->rate_est); 508 goto destroy_class; 509 } 510 sch_tree_lock(sch); 511 qfq_init_agg(q, new_agg, lmax, weight); 512 } 513 if (existing) 514 qfq_deact_rm_from_agg(q, cl); 515 else 516 qdisc_class_hash_insert(&q->clhash, &cl->common); 517 qfq_add_to_agg(q, new_agg, cl); 518 sch_tree_unlock(sch); 519 qdisc_class_hash_grow(sch, &q->clhash); 520 521 *arg = (unsigned long)cl; 522 return 0; 523 524destroy_class: 525 qdisc_put(cl->qdisc); 526 kfree(cl); 527 return err; 528} 529 530static void qfq_destroy_class(struct Qdisc *sch, struct qfq_class *cl) 531{ 532 struct qfq_sched *q = qdisc_priv(sch); 533 534 qfq_rm_from_agg(q, cl); 535 gen_kill_estimator(&cl->rate_est); 536 qdisc_put(cl->qdisc); 537 kfree(cl); 538} 539 540static int qfq_delete_class(struct Qdisc *sch, unsigned long arg, 541 struct netlink_ext_ack *extack) 542{ 543 struct qfq_sched *q = qdisc_priv(sch); 544 struct qfq_class *cl = (struct qfq_class *)arg; 545 546 if (qdisc_class_in_use(&cl->common)) { 547 NL_SET_ERR_MSG_MOD(extack, "QFQ class in use"); 548 return -EBUSY; 549 } 550 551 sch_tree_lock(sch); 552 553 qdisc_purge_queue(cl->qdisc); 554 qdisc_class_hash_remove(&q->clhash, &cl->common); 555 556 sch_tree_unlock(sch); 557 558 qfq_destroy_class(sch, cl); 559 return 0; 560} 561 562static unsigned long qfq_search_class(struct Qdisc *sch, u32 classid) 563{ 564 return (unsigned long)qfq_find_class(sch, classid); 565} 566 567static struct tcf_block *qfq_tcf_block(struct Qdisc *sch, unsigned long cl, 568 struct netlink_ext_ack *extack) 569{ 570 struct qfq_sched *q = qdisc_priv(sch); 571 572 if (cl) 573 return NULL; 574 575 return q->block; 576} 577 578static unsigned long qfq_bind_tcf(struct Qdisc *sch, unsigned long parent, 579 u32 classid) 580{ 581 struct qfq_class *cl = qfq_find_class(sch, classid); 582 583 if (cl) 584 qdisc_class_get(&cl->common); 585 586 return (unsigned long)cl; 587} 588 589static void qfq_unbind_tcf(struct Qdisc *sch, unsigned long arg) 590{ 591 struct qfq_class *cl = (struct qfq_class *)arg; 592 593 qdisc_class_put(&cl->common); 594} 595 596static int qfq_graft_class(struct Qdisc *sch, unsigned long arg, 597 struct Qdisc *new, struct Qdisc **old, 598 struct netlink_ext_ack *extack) 599{ 600 struct qfq_class *cl = (struct qfq_class *)arg; 601 602 if (new == NULL) { 603 new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, 604 cl->common.classid, NULL); 605 if (new == NULL) 606 new = &noop_qdisc; 607 } 608 609 *old = qdisc_replace(sch, new, &cl->qdisc); 610 return 0; 611} 612 613static struct Qdisc *qfq_class_leaf(struct Qdisc *sch, unsigned long arg) 614{ 615 struct qfq_class *cl = (struct qfq_class *)arg; 616 617 return cl->qdisc; 618} 619 620static int qfq_dump_class(struct Qdisc *sch, unsigned long arg, 621 struct sk_buff *skb, struct tcmsg *tcm) 622{ 623 struct qfq_class *cl = (struct qfq_class *)arg; 624 struct nlattr *nest; 625 626 tcm->tcm_parent = TC_H_ROOT; 627 tcm->tcm_handle = cl->common.classid; 628 tcm->tcm_info = cl->qdisc->handle; 629 630 nest = nla_nest_start_noflag(skb, TCA_OPTIONS); 631 if (nest == NULL) 632 goto nla_put_failure; 633 if (nla_put_u32(skb, TCA_QFQ_WEIGHT, cl->agg->class_weight) || 634 nla_put_u32(skb, TCA_QFQ_LMAX, cl->agg->lmax)) 635 goto nla_put_failure; 636 return nla_nest_end(skb, nest); 637 638nla_put_failure: 639 nla_nest_cancel(skb, nest); 640 return -EMSGSIZE; 641} 642 643static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg, 644 struct gnet_dump *d) 645{ 646 struct qfq_class *cl = (struct qfq_class *)arg; 647 struct tc_qfq_stats xstats; 648 649 memset(&xstats, 0, sizeof(xstats)); 650 651 xstats.weight = cl->agg->class_weight; 652 xstats.lmax = cl->agg->lmax; 653 654 if (gnet_stats_copy_basic(d, NULL, &cl->bstats, true) < 0 || 655 gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 || 656 qdisc_qstats_copy(d, cl->qdisc) < 0) 657 return -1; 658 659 return gnet_stats_copy_app(d, &xstats, sizeof(xstats)); 660} 661 662static void qfq_walk(struct Qdisc *sch, struct qdisc_walker *arg) 663{ 664 struct qfq_sched *q = qdisc_priv(sch); 665 struct qfq_class *cl; 666 unsigned int i; 667 668 if (arg->stop) 669 return; 670 671 for (i = 0; i < q->clhash.hashsize; i++) { 672 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { 673 if (!tc_qdisc_stats_dump(sch, (unsigned long)cl, arg)) 674 return; 675 } 676 } 677} 678 679static struct qfq_class *qfq_classify(struct sk_buff *skb, struct Qdisc *sch, 680 int *qerr) 681{ 682 struct qfq_sched *q = qdisc_priv(sch); 683 struct qfq_class *cl; 684 struct tcf_result res; 685 struct tcf_proto *fl; 686 int result; 687 688 if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) { 689 pr_debug("qfq_classify: found %d\n", skb->priority); 690 cl = qfq_find_class(sch, skb->priority); 691 if (cl != NULL) 692 return cl; 693 } 694 695 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; 696 fl = rcu_dereference_bh(q->filter_list); 697 result = tcf_classify(skb, NULL, fl, &res, false); 698 if (result >= 0) { 699#ifdef CONFIG_NET_CLS_ACT 700 switch (result) { 701 case TC_ACT_QUEUED: 702 case TC_ACT_STOLEN: 703 case TC_ACT_TRAP: 704 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN; 705 fallthrough; 706 case TC_ACT_SHOT: 707 return NULL; 708 } 709#endif 710 cl = (struct qfq_class *)res.class; 711 if (cl == NULL) 712 cl = qfq_find_class(sch, res.classid); 713 return cl; 714 } 715 716 return NULL; 717} 718 719/* Generic comparison function, handling wraparound. */ 720static inline int qfq_gt(u64 a, u64 b) 721{ 722 return (s64)(a - b) > 0; 723} 724 725/* Round a precise timestamp to its slotted value. */ 726static inline u64 qfq_round_down(u64 ts, unsigned int shift) 727{ 728 return ts & ~((1ULL << shift) - 1); 729} 730 731/* return the pointer to the group with lowest index in the bitmap */ 732static inline struct qfq_group *qfq_ffs(struct qfq_sched *q, 733 unsigned long bitmap) 734{ 735 int index = __ffs(bitmap); 736 return &q->groups[index]; 737} 738/* Calculate a mask to mimic what would be ffs_from(). */ 739static inline unsigned long mask_from(unsigned long bitmap, int from) 740{ 741 return bitmap & ~((1UL << from) - 1); 742} 743 744/* 745 * The state computation relies on ER=0, IR=1, EB=2, IB=3 746 * First compute eligibility comparing grp->S, q->V, 747 * then check if someone is blocking us and possibly add EB 748 */ 749static int qfq_calc_state(struct qfq_sched *q, const struct qfq_group *grp) 750{ 751 /* if S > V we are not eligible */ 752 unsigned int state = qfq_gt(grp->S, q->V); 753 unsigned long mask = mask_from(q->bitmaps[ER], grp->index); 754 struct qfq_group *next; 755 756 if (mask) { 757 next = qfq_ffs(q, mask); 758 if (qfq_gt(grp->F, next->F)) 759 state |= EB; 760 } 761 762 return state; 763} 764 765 766/* 767 * In principle 768 * q->bitmaps[dst] |= q->bitmaps[src] & mask; 769 * q->bitmaps[src] &= ~mask; 770 * but we should make sure that src != dst 771 */ 772static inline void qfq_move_groups(struct qfq_sched *q, unsigned long mask, 773 int src, int dst) 774{ 775 q->bitmaps[dst] |= q->bitmaps[src] & mask; 776 q->bitmaps[src] &= ~mask; 777} 778 779static void qfq_unblock_groups(struct qfq_sched *q, int index, u64 old_F) 780{ 781 unsigned long mask = mask_from(q->bitmaps[ER], index + 1); 782 struct qfq_group *next; 783 784 if (mask) { 785 next = qfq_ffs(q, mask); 786 if (!qfq_gt(next->F, old_F)) 787 return; 788 } 789 790 mask = (1UL << index) - 1; 791 qfq_move_groups(q, mask, EB, ER); 792 qfq_move_groups(q, mask, IB, IR); 793} 794 795/* 796 * perhaps 797 * 798 old_V ^= q->V; 799 old_V >>= q->min_slot_shift; 800 if (old_V) { 801 ... 802 } 803 * 804 */ 805static void qfq_make_eligible(struct qfq_sched *q) 806{ 807 unsigned long vslot = q->V >> q->min_slot_shift; 808 unsigned long old_vslot = q->oldV >> q->min_slot_shift; 809 810 if (vslot != old_vslot) { 811 unsigned long mask; 812 int last_flip_pos = fls(vslot ^ old_vslot); 813 814 if (last_flip_pos > 31) /* higher than the number of groups */ 815 mask = ~0UL; /* make all groups eligible */ 816 else 817 mask = (1UL << last_flip_pos) - 1; 818 819 qfq_move_groups(q, mask, IR, ER); 820 qfq_move_groups(q, mask, IB, EB); 821 } 822} 823 824/* 825 * The index of the slot in which the input aggregate agg is to be 826 * inserted must not be higher than QFQ_MAX_SLOTS-2. There is a '-2' 827 * and not a '-1' because the start time of the group may be moved 828 * backward by one slot after the aggregate has been inserted, and 829 * this would cause non-empty slots to be right-shifted by one 830 * position. 831 * 832 * QFQ+ fully satisfies this bound to the slot index if the parameters 833 * of the classes are not changed dynamically, and if QFQ+ never 834 * happens to postpone the service of agg unjustly, i.e., it never 835 * happens that the aggregate becomes backlogged and eligible, or just 836 * eligible, while an aggregate with a higher approximated finish time 837 * is being served. In particular, in this case QFQ+ guarantees that 838 * the timestamps of agg are low enough that the slot index is never 839 * higher than 2. Unfortunately, QFQ+ cannot provide the same 840 * guarantee if it happens to unjustly postpone the service of agg, or 841 * if the parameters of some class are changed. 842 * 843 * As for the first event, i.e., an out-of-order service, the 844 * upper bound to the slot index guaranteed by QFQ+ grows to 845 * 2 + 846 * QFQ_MAX_AGG_CLASSES * ((1<<QFQ_MTU_SHIFT)/QFQ_MIN_LMAX) * 847 * (current_max_weight/current_wsum) <= 2 + 8 * 128 * 1. 848 * 849 * The following function deals with this problem by backward-shifting 850 * the timestamps of agg, if needed, so as to guarantee that the slot 851 * index is never higher than QFQ_MAX_SLOTS-2. This backward-shift may 852 * cause the service of other aggregates to be postponed, yet the 853 * worst-case guarantees of these aggregates are not violated. In 854 * fact, in case of no out-of-order service, the timestamps of agg 855 * would have been even lower than they are after the backward shift, 856 * because QFQ+ would have guaranteed a maximum value equal to 2 for 857 * the slot index, and 2 < QFQ_MAX_SLOTS-2. Hence the aggregates whose 858 * service is postponed because of the backward-shift would have 859 * however waited for the service of agg before being served. 860 * 861 * The other event that may cause the slot index to be higher than 2 862 * for agg is a recent change of the parameters of some class. If the 863 * weight of a class is increased or the lmax (max_pkt_size) of the 864 * class is decreased, then a new aggregate with smaller slot size 865 * than the original parent aggregate of the class may happen to be 866 * activated. The activation of this aggregate should be properly 867 * delayed to when the service of the class has finished in the ideal 868 * system tracked by QFQ+. If the activation of the aggregate is not 869 * delayed to this reference time instant, then this aggregate may be 870 * unjustly served before other aggregates waiting for service. This 871 * may cause the above bound to the slot index to be violated for some 872 * of these unlucky aggregates. 873 * 874 * Instead of delaying the activation of the new aggregate, which is 875 * quite complex, the above-discussed capping of the slot index is 876 * used to handle also the consequences of a change of the parameters 877 * of a class. 878 */ 879static void qfq_slot_insert(struct qfq_group *grp, struct qfq_aggregate *agg, 880 u64 roundedS) 881{ 882 u64 slot = (roundedS - grp->S) >> grp->slot_shift; 883 unsigned int i; /* slot index in the bucket list */ 884 885 if (unlikely(slot > QFQ_MAX_SLOTS - 2)) { 886 u64 deltaS = roundedS - grp->S - 887 ((u64)(QFQ_MAX_SLOTS - 2)<<grp->slot_shift); 888 agg->S -= deltaS; 889 agg->F -= deltaS; 890 slot = QFQ_MAX_SLOTS - 2; 891 } 892 893 i = (grp->front + slot) % QFQ_MAX_SLOTS; 894 895 hlist_add_head(&agg->next, &grp->slots[i]); 896 __set_bit(slot, &grp->full_slots); 897} 898 899/* Maybe introduce hlist_first_entry?? */ 900static struct qfq_aggregate *qfq_slot_head(struct qfq_group *grp) 901{ 902 return hlist_entry(grp->slots[grp->front].first, 903 struct qfq_aggregate, next); 904} 905 906/* 907 * remove the entry from the slot 908 */ 909static void qfq_front_slot_remove(struct qfq_group *grp) 910{ 911 struct qfq_aggregate *agg = qfq_slot_head(grp); 912 913 BUG_ON(!agg); 914 hlist_del(&agg->next); 915 if (hlist_empty(&grp->slots[grp->front])) 916 __clear_bit(0, &grp->full_slots); 917} 918 919/* 920 * Returns the first aggregate in the first non-empty bucket of the 921 * group. As a side effect, adjusts the bucket list so the first 922 * non-empty bucket is at position 0 in full_slots. 923 */ 924static struct qfq_aggregate *qfq_slot_scan(struct qfq_group *grp) 925{ 926 unsigned int i; 927 928 pr_debug("qfq slot_scan: grp %u full %#lx\n", 929 grp->index, grp->full_slots); 930 931 if (grp->full_slots == 0) 932 return NULL; 933 934 i = __ffs(grp->full_slots); /* zero based */ 935 if (i > 0) { 936 grp->front = (grp->front + i) % QFQ_MAX_SLOTS; 937 grp->full_slots >>= i; 938 } 939 940 return qfq_slot_head(grp); 941} 942 943/* 944 * adjust the bucket list. When the start time of a group decreases, 945 * we move the index down (modulo QFQ_MAX_SLOTS) so we don't need to 946 * move the objects. The mask of occupied slots must be shifted 947 * because we use ffs() to find the first non-empty slot. 948 * This covers decreases in the group's start time, but what about 949 * increases of the start time ? 950 * Here too we should make sure that i is less than 32 951 */ 952static void qfq_slot_rotate(struct qfq_group *grp, u64 roundedS) 953{ 954 unsigned int i = (grp->S - roundedS) >> grp->slot_shift; 955 956 grp->full_slots <<= i; 957 grp->front = (grp->front - i) % QFQ_MAX_SLOTS; 958} 959 960static void qfq_update_eligible(struct qfq_sched *q) 961{ 962 struct qfq_group *grp; 963 unsigned long ineligible; 964 965 ineligible = q->bitmaps[IR] | q->bitmaps[IB]; 966 if (ineligible) { 967 if (!q->bitmaps[ER]) { 968 grp = qfq_ffs(q, ineligible); 969 if (qfq_gt(grp->S, q->V)) 970 q->V = grp->S; 971 } 972 qfq_make_eligible(q); 973 } 974} 975 976/* Dequeue head packet of the head class in the DRR queue of the aggregate. */ 977static struct sk_buff *agg_dequeue(struct qfq_aggregate *agg, 978 struct qfq_class *cl, unsigned int len) 979{ 980 struct sk_buff *skb = qdisc_dequeue_peeked(cl->qdisc); 981 982 if (!skb) 983 return NULL; 984 985 cl->deficit -= (int) len; 986 987 if (cl->qdisc->q.qlen == 0) /* no more packets, remove from list */ 988 list_del(&cl->alist); 989 else if (cl->deficit < qdisc_pkt_len(cl->qdisc->ops->peek(cl->qdisc))) { 990 cl->deficit += agg->lmax; 991 list_move_tail(&cl->alist, &agg->active); 992 } 993 994 return skb; 995} 996 997static inline struct sk_buff *qfq_peek_skb(struct qfq_aggregate *agg, 998 struct qfq_class **cl, 999 unsigned int *len) 1000{ 1001 struct sk_buff *skb; 1002 1003 *cl = list_first_entry(&agg->active, struct qfq_class, alist); 1004 skb = (*cl)->qdisc->ops->peek((*cl)->qdisc); 1005 if (skb == NULL) 1006 qdisc_warn_nonwc("qfq_dequeue", (*cl)->qdisc); 1007 else 1008 *len = qdisc_pkt_len(skb); 1009 1010 return skb; 1011} 1012 1013/* Update F according to the actual service received by the aggregate. */ 1014static inline void charge_actual_service(struct qfq_aggregate *agg) 1015{ 1016 /* Compute the service received by the aggregate, taking into 1017 * account that, after decreasing the number of classes in 1018 * agg, it may happen that 1019 * agg->initial_budget - agg->budget > agg->bugdetmax 1020 */ 1021 u32 service_received = min(agg->budgetmax, 1022 agg->initial_budget - agg->budget); 1023 1024 agg->F = agg->S + (u64)service_received * agg->inv_w; 1025} 1026 1027/* Assign a reasonable start time for a new aggregate in group i. 1028 * Admissible values for \hat(F) are multiples of \sigma_i 1029 * no greater than V+\sigma_i . Larger values mean that 1030 * we had a wraparound so we consider the timestamp to be stale. 1031 * 1032 * If F is not stale and F >= V then we set S = F. 1033 * Otherwise we should assign S = V, but this may violate 1034 * the ordering in EB (see [2]). So, if we have groups in ER, 1035 * set S to the F_j of the first group j which would be blocking us. 1036 * We are guaranteed not to move S backward because 1037 * otherwise our group i would still be blocked. 1038 */ 1039static void qfq_update_start(struct qfq_sched *q, struct qfq_aggregate *agg) 1040{ 1041 unsigned long mask; 1042 u64 limit, roundedF; 1043 int slot_shift = agg->grp->slot_shift; 1044 1045 roundedF = qfq_round_down(agg->F, slot_shift); 1046 limit = qfq_round_down(q->V, slot_shift) + (1ULL << slot_shift); 1047 1048 if (!qfq_gt(agg->F, q->V) || qfq_gt(roundedF, limit)) { 1049 /* timestamp was stale */ 1050 mask = mask_from(q->bitmaps[ER], agg->grp->index); 1051 if (mask) { 1052 struct qfq_group *next = qfq_ffs(q, mask); 1053 if (qfq_gt(roundedF, next->F)) { 1054 if (qfq_gt(limit, next->F)) 1055 agg->S = next->F; 1056 else /* preserve timestamp correctness */ 1057 agg->S = limit; 1058 return; 1059 } 1060 } 1061 agg->S = q->V; 1062 } else /* timestamp is not stale */ 1063 agg->S = agg->F; 1064} 1065 1066/* Update the timestamps of agg before scheduling/rescheduling it for 1067 * service. In particular, assign to agg->F its maximum possible 1068 * value, i.e., the virtual finish time with which the aggregate 1069 * should be labeled if it used all its budget once in service. 1070 */ 1071static inline void 1072qfq_update_agg_ts(struct qfq_sched *q, 1073 struct qfq_aggregate *agg, enum update_reason reason) 1074{ 1075 if (reason != requeue) 1076 qfq_update_start(q, agg); 1077 else /* just charge agg for the service received */ 1078 agg->S = agg->F; 1079 1080 agg->F = agg->S + (u64)agg->budgetmax * agg->inv_w; 1081} 1082 1083static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg); 1084 1085static struct sk_buff *qfq_dequeue(struct Qdisc *sch) 1086{ 1087 struct qfq_sched *q = qdisc_priv(sch); 1088 struct qfq_aggregate *in_serv_agg = q->in_serv_agg; 1089 struct qfq_class *cl; 1090 struct sk_buff *skb = NULL; 1091 /* next-packet len, 0 means no more active classes in in-service agg */ 1092 unsigned int len = 0; 1093 1094 if (in_serv_agg == NULL) 1095 return NULL; 1096 1097 if (!list_empty(&in_serv_agg->active)) 1098 skb = qfq_peek_skb(in_serv_agg, &cl, &len); 1099 1100 /* 1101 * If there are no active classes in the in-service aggregate, 1102 * or if the aggregate has not enough budget to serve its next 1103 * class, then choose the next aggregate to serve. 1104 */ 1105 if (len == 0 || in_serv_agg->budget < len) { 1106 charge_actual_service(in_serv_agg); 1107 1108 /* recharge the budget of the aggregate */ 1109 in_serv_agg->initial_budget = in_serv_agg->budget = 1110 in_serv_agg->budgetmax; 1111 1112 if (!list_empty(&in_serv_agg->active)) { 1113 /* 1114 * Still active: reschedule for 1115 * service. Possible optimization: if no other 1116 * aggregate is active, then there is no point 1117 * in rescheduling this aggregate, and we can 1118 * just keep it as the in-service one. This 1119 * should be however a corner case, and to 1120 * handle it, we would need to maintain an 1121 * extra num_active_aggs field. 1122 */ 1123 qfq_update_agg_ts(q, in_serv_agg, requeue); 1124 qfq_schedule_agg(q, in_serv_agg); 1125 } else if (sch->q.qlen == 0) { /* no aggregate to serve */ 1126 q->in_serv_agg = NULL; 1127 return NULL; 1128 } 1129 1130 /* 1131 * If we get here, there are other aggregates queued: 1132 * choose the new aggregate to serve. 1133 */ 1134 in_serv_agg = q->in_serv_agg = qfq_choose_next_agg(q); 1135 skb = qfq_peek_skb(in_serv_agg, &cl, &len); 1136 } 1137 if (!skb) 1138 return NULL; 1139 1140 sch->q.qlen--; 1141 1142 skb = agg_dequeue(in_serv_agg, cl, len); 1143 1144 if (!skb) { 1145 sch->q.qlen++; 1146 return NULL; 1147 } 1148 1149 qdisc_qstats_backlog_dec(sch, skb); 1150 qdisc_bstats_update(sch, skb); 1151 1152 /* If lmax is lowered, through qfq_change_class, for a class 1153 * owning pending packets with larger size than the new value 1154 * of lmax, then the following condition may hold. 1155 */ 1156 if (unlikely(in_serv_agg->budget < len)) 1157 in_serv_agg->budget = 0; 1158 else 1159 in_serv_agg->budget -= len; 1160 1161 q->V += (u64)len * q->iwsum; 1162 pr_debug("qfq dequeue: len %u F %lld now %lld\n", 1163 len, (unsigned long long) in_serv_agg->F, 1164 (unsigned long long) q->V); 1165 1166 return skb; 1167} 1168 1169static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *q) 1170{ 1171 struct qfq_group *grp; 1172 struct qfq_aggregate *agg, *new_front_agg; 1173 u64 old_F; 1174 1175 qfq_update_eligible(q); 1176 q->oldV = q->V; 1177 1178 if (!q->bitmaps[ER]) 1179 return NULL; 1180 1181 grp = qfq_ffs(q, q->bitmaps[ER]); 1182 old_F = grp->F; 1183 1184 agg = qfq_slot_head(grp); 1185 1186 /* agg starts to be served, remove it from schedule */ 1187 qfq_front_slot_remove(grp); 1188 1189 new_front_agg = qfq_slot_scan(grp); 1190 1191 if (new_front_agg == NULL) /* group is now inactive, remove from ER */ 1192 __clear_bit(grp->index, &q->bitmaps[ER]); 1193 else { 1194 u64 roundedS = qfq_round_down(new_front_agg->S, 1195 grp->slot_shift); 1196 unsigned int s; 1197 1198 if (grp->S == roundedS) 1199 return agg; 1200 grp->S = roundedS; 1201 grp->F = roundedS + (2ULL << grp->slot_shift); 1202 __clear_bit(grp->index, &q->bitmaps[ER]); 1203 s = qfq_calc_state(q, grp); 1204 __set_bit(grp->index, &q->bitmaps[s]); 1205 } 1206 1207 qfq_unblock_groups(q, grp->index, old_F); 1208 1209 return agg; 1210} 1211 1212static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, 1213 struct sk_buff **to_free) 1214{ 1215 unsigned int len = qdisc_pkt_len(skb), gso_segs; 1216 struct qfq_sched *q = qdisc_priv(sch); 1217 struct qfq_class *cl; 1218 struct qfq_aggregate *agg; 1219 int err = 0; 1220 bool first; 1221 1222 cl = qfq_classify(skb, sch, &err); 1223 if (cl == NULL) { 1224 if (err & __NET_XMIT_BYPASS) 1225 qdisc_qstats_drop(sch); 1226 __qdisc_drop(skb, to_free); 1227 return err; 1228 } 1229 pr_debug("qfq_enqueue: cl = %x\n", cl->common.classid); 1230 1231 if (unlikely(cl->agg->lmax < len)) { 1232 pr_debug("qfq: increasing maxpkt from %u to %u for class %u", 1233 cl->agg->lmax, len, cl->common.classid); 1234 err = qfq_change_agg(sch, cl, cl->agg->class_weight, len); 1235 if (err) { 1236 cl->qstats.drops++; 1237 return qdisc_drop(skb, sch, to_free); 1238 } 1239 } 1240 1241 gso_segs = skb_is_gso(skb) ? skb_shinfo(skb)->gso_segs : 1; 1242 first = !cl->qdisc->q.qlen; 1243 err = qdisc_enqueue(skb, cl->qdisc, to_free); 1244 if (unlikely(err != NET_XMIT_SUCCESS)) { 1245 pr_debug("qfq_enqueue: enqueue failed %d\n", err); 1246 if (net_xmit_drop_count(err)) { 1247 cl->qstats.drops++; 1248 qdisc_qstats_drop(sch); 1249 } 1250 return err; 1251 } 1252 1253 _bstats_update(&cl->bstats, len, gso_segs); 1254 sch->qstats.backlog += len; 1255 ++sch->q.qlen; 1256 1257 agg = cl->agg; 1258 /* if the queue was not empty, then done here */ 1259 if (!first) { 1260 if (unlikely(skb == cl->qdisc->ops->peek(cl->qdisc)) && 1261 list_first_entry(&agg->active, struct qfq_class, alist) 1262 == cl && cl->deficit < len) 1263 list_move_tail(&cl->alist, &agg->active); 1264 1265 return err; 1266 } 1267 1268 /* schedule class for service within the aggregate */ 1269 cl->deficit = agg->lmax; 1270 list_add_tail(&cl->alist, &agg->active); 1271 1272 if (list_first_entry(&agg->active, struct qfq_class, alist) != cl || 1273 q->in_serv_agg == agg) 1274 return err; /* non-empty or in service, nothing else to do */ 1275 1276 qfq_activate_agg(q, agg, enqueue); 1277 1278 return err; 1279} 1280 1281/* 1282 * Schedule aggregate according to its timestamps. 1283 */ 1284static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg) 1285{ 1286 struct qfq_group *grp = agg->grp; 1287 u64 roundedS; 1288 int s; 1289 1290 roundedS = qfq_round_down(agg->S, grp->slot_shift); 1291 1292 /* 1293 * Insert agg in the correct bucket. 1294 * If agg->S >= grp->S we don't need to adjust the 1295 * bucket list and simply go to the insertion phase. 1296 * Otherwise grp->S is decreasing, we must make room 1297 * in the bucket list, and also recompute the group state. 1298 * Finally, if there were no flows in this group and nobody 1299 * was in ER make sure to adjust V. 1300 */ 1301 if (grp->full_slots) { 1302 if (!qfq_gt(grp->S, agg->S)) 1303 goto skip_update; 1304 1305 /* create a slot for this agg->S */ 1306 qfq_slot_rotate(grp, roundedS); 1307 /* group was surely ineligible, remove */ 1308 __clear_bit(grp->index, &q->bitmaps[IR]); 1309 __clear_bit(grp->index, &q->bitmaps[IB]); 1310 } else if (!q->bitmaps[ER] && qfq_gt(roundedS, q->V) && 1311 q->in_serv_agg == NULL) 1312 q->V = roundedS; 1313 1314 grp->S = roundedS; 1315 grp->F = roundedS + (2ULL << grp->slot_shift); 1316 s = qfq_calc_state(q, grp); 1317 __set_bit(grp->index, &q->bitmaps[s]); 1318 1319 pr_debug("qfq enqueue: new state %d %#lx S %lld F %lld V %lld\n", 1320 s, q->bitmaps[s], 1321 (unsigned long long) agg->S, 1322 (unsigned long long) agg->F, 1323 (unsigned long long) q->V); 1324 1325skip_update: 1326 qfq_slot_insert(grp, agg, roundedS); 1327} 1328 1329 1330/* Update agg ts and schedule agg for service */ 1331static void qfq_activate_agg(struct qfq_sched *q, struct qfq_aggregate *agg, 1332 enum update_reason reason) 1333{ 1334 agg->initial_budget = agg->budget = agg->budgetmax; /* recharge budg. */ 1335 1336 qfq_update_agg_ts(q, agg, reason); 1337 if (q->in_serv_agg == NULL) { /* no aggr. in service or scheduled */ 1338 q->in_serv_agg = agg; /* start serving this aggregate */ 1339 /* update V: to be in service, agg must be eligible */ 1340 q->oldV = q->V = agg->S; 1341 } else if (agg != q->in_serv_agg) 1342 qfq_schedule_agg(q, agg); 1343} 1344 1345static void qfq_slot_remove(struct qfq_sched *q, struct qfq_group *grp, 1346 struct qfq_aggregate *agg) 1347{ 1348 unsigned int i, offset; 1349 u64 roundedS; 1350 1351 roundedS = qfq_round_down(agg->S, grp->slot_shift); 1352 offset = (roundedS - grp->S) >> grp->slot_shift; 1353 1354 i = (grp->front + offset) % QFQ_MAX_SLOTS; 1355 1356 hlist_del(&agg->next); 1357 if (hlist_empty(&grp->slots[i])) 1358 __clear_bit(offset, &grp->full_slots); 1359} 1360 1361/* 1362 * Called to forcibly deschedule an aggregate. If the aggregate is 1363 * not in the front bucket, or if the latter has other aggregates in 1364 * the front bucket, we can simply remove the aggregate with no other 1365 * side effects. 1366 * Otherwise we must propagate the event up. 1367 */ 1368static void qfq_deactivate_agg(struct qfq_sched *q, struct qfq_aggregate *agg) 1369{ 1370 struct qfq_group *grp = agg->grp; 1371 unsigned long mask; 1372 u64 roundedS; 1373 int s; 1374 1375 if (agg == q->in_serv_agg) { 1376 charge_actual_service(agg); 1377 q->in_serv_agg = qfq_choose_next_agg(q); 1378 return; 1379 } 1380 1381 agg->F = agg->S; 1382 qfq_slot_remove(q, grp, agg); 1383 1384 if (!grp->full_slots) { 1385 __clear_bit(grp->index, &q->bitmaps[IR]); 1386 __clear_bit(grp->index, &q->bitmaps[EB]); 1387 __clear_bit(grp->index, &q->bitmaps[IB]); 1388 1389 if (test_bit(grp->index, &q->bitmaps[ER]) && 1390 !(q->bitmaps[ER] & ~((1UL << grp->index) - 1))) { 1391 mask = q->bitmaps[ER] & ((1UL << grp->index) - 1); 1392 if (mask) 1393 mask = ~((1UL << __fls(mask)) - 1); 1394 else 1395 mask = ~0UL; 1396 qfq_move_groups(q, mask, EB, ER); 1397 qfq_move_groups(q, mask, IB, IR); 1398 } 1399 __clear_bit(grp->index, &q->bitmaps[ER]); 1400 } else if (hlist_empty(&grp->slots[grp->front])) { 1401 agg = qfq_slot_scan(grp); 1402 roundedS = qfq_round_down(agg->S, grp->slot_shift); 1403 if (grp->S != roundedS) { 1404 __clear_bit(grp->index, &q->bitmaps[ER]); 1405 __clear_bit(grp->index, &q->bitmaps[IR]); 1406 __clear_bit(grp->index, &q->bitmaps[EB]); 1407 __clear_bit(grp->index, &q->bitmaps[IB]); 1408 grp->S = roundedS; 1409 grp->F = roundedS + (2ULL << grp->slot_shift); 1410 s = qfq_calc_state(q, grp); 1411 __set_bit(grp->index, &q->bitmaps[s]); 1412 } 1413 } 1414} 1415 1416static void qfq_qlen_notify(struct Qdisc *sch, unsigned long arg) 1417{ 1418 struct qfq_sched *q = qdisc_priv(sch); 1419 struct qfq_class *cl = (struct qfq_class *)arg; 1420 1421 qfq_deactivate_class(q, cl); 1422} 1423 1424static int qfq_init_qdisc(struct Qdisc *sch, struct nlattr *opt, 1425 struct netlink_ext_ack *extack) 1426{ 1427 struct qfq_sched *q = qdisc_priv(sch); 1428 struct qfq_group *grp; 1429 int i, j, err; 1430 u32 max_cl_shift, maxbudg_shift, max_classes; 1431 1432 err = tcf_block_get(&q->block, &q->filter_list, sch, extack); 1433 if (err) 1434 return err; 1435 1436 err = qdisc_class_hash_init(&q->clhash); 1437 if (err < 0) 1438 return err; 1439 1440 max_classes = min_t(u64, (u64)qdisc_dev(sch)->tx_queue_len + 1, 1441 QFQ_MAX_AGG_CLASSES); 1442 /* max_cl_shift = floor(log_2(max_classes)) */ 1443 max_cl_shift = __fls(max_classes); 1444 q->max_agg_classes = 1<<max_cl_shift; 1445 1446 /* maxbudg_shift = log2(max_len * max_classes_per_agg) */ 1447 maxbudg_shift = QFQ_MTU_SHIFT + max_cl_shift; 1448 q->min_slot_shift = FRAC_BITS + maxbudg_shift - QFQ_MAX_INDEX; 1449 1450 for (i = 0; i <= QFQ_MAX_INDEX; i++) { 1451 grp = &q->groups[i]; 1452 grp->index = i; 1453 grp->slot_shift = q->min_slot_shift + i; 1454 for (j = 0; j < QFQ_MAX_SLOTS; j++) 1455 INIT_HLIST_HEAD(&grp->slots[j]); 1456 } 1457 1458 INIT_HLIST_HEAD(&q->nonfull_aggs); 1459 1460 return 0; 1461} 1462 1463static void qfq_reset_qdisc(struct Qdisc *sch) 1464{ 1465 struct qfq_sched *q = qdisc_priv(sch); 1466 struct qfq_class *cl; 1467 unsigned int i; 1468 1469 for (i = 0; i < q->clhash.hashsize; i++) { 1470 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { 1471 if (cl->qdisc->q.qlen > 0) 1472 qfq_deactivate_class(q, cl); 1473 1474 qdisc_reset(cl->qdisc); 1475 } 1476 } 1477} 1478 1479static void qfq_destroy_qdisc(struct Qdisc *sch) 1480{ 1481 struct qfq_sched *q = qdisc_priv(sch); 1482 struct qfq_class *cl; 1483 struct hlist_node *next; 1484 unsigned int i; 1485 1486 tcf_block_put(q->block); 1487 1488 for (i = 0; i < q->clhash.hashsize; i++) { 1489 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i], 1490 common.hnode) { 1491 qfq_destroy_class(sch, cl); 1492 } 1493 } 1494 qdisc_class_hash_destroy(&q->clhash); 1495} 1496 1497static const struct Qdisc_class_ops qfq_class_ops = { 1498 .change = qfq_change_class, 1499 .delete = qfq_delete_class, 1500 .find = qfq_search_class, 1501 .tcf_block = qfq_tcf_block, 1502 .bind_tcf = qfq_bind_tcf, 1503 .unbind_tcf = qfq_unbind_tcf, 1504 .graft = qfq_graft_class, 1505 .leaf = qfq_class_leaf, 1506 .qlen_notify = qfq_qlen_notify, 1507 .dump = qfq_dump_class, 1508 .dump_stats = qfq_dump_class_stats, 1509 .walk = qfq_walk, 1510}; 1511 1512static struct Qdisc_ops qfq_qdisc_ops __read_mostly = { 1513 .cl_ops = &qfq_class_ops, 1514 .id = "qfq", 1515 .priv_size = sizeof(struct qfq_sched), 1516 .enqueue = qfq_enqueue, 1517 .dequeue = qfq_dequeue, 1518 .peek = qdisc_peek_dequeued, 1519 .init = qfq_init_qdisc, 1520 .reset = qfq_reset_qdisc, 1521 .destroy = qfq_destroy_qdisc, 1522 .owner = THIS_MODULE, 1523}; 1524MODULE_ALIAS_NET_SCH("qfq"); 1525 1526static int __init qfq_init(void) 1527{ 1528 return register_qdisc(&qfq_qdisc_ops); 1529} 1530 1531static void __exit qfq_exit(void) 1532{ 1533 unregister_qdisc(&qfq_qdisc_ops); 1534} 1535 1536module_init(qfq_init); 1537module_exit(qfq_exit); 1538MODULE_LICENSE("GPL"); 1539MODULE_DESCRIPTION("Quick Fair Queueing Plus qdisc"); 1540