1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * net/sched/sch_sfq.c Stochastic Fairness Queueing discipline. 4 * 5 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> 6 */ 7 8 #include <linux/module.h> 9 #include <linux/types.h> 10 #include <linux/kernel.h> 11 #include <linux/jiffies.h> 12 #include <linux/string.h> 13 #include <linux/in.h> 14 #include <linux/errno.h> 15 #include <linux/init.h> 16 #include <linux/skbuff.h> 17 #include <linux/siphash.h> 18 #include <linux/slab.h> 19 #include <linux/vmalloc.h> 20 #include <net/netlink.h> 21 #include <net/pkt_sched.h> 22 #include <net/pkt_cls.h> 23 #include <net/red.h> 24 25 26 /* Stochastic Fairness Queuing algorithm. 27 ======================================= 28 29 Source: 30 Paul E. McKenney "Stochastic Fairness Queuing", 31 IEEE INFOCOMM'90 Proceedings, San Francisco, 1990. 32 33 Paul E. McKenney "Stochastic Fairness Queuing", 34 "Interworking: Research and Experience", v.2, 1991, p.113-131. 35 36 37 See also: 38 M. Shreedhar and George Varghese "Efficient Fair 39 Queuing using Deficit Round Robin", Proc. SIGCOMM 95. 40 41 42 This is not the thing that is usually called (W)FQ nowadays. 43 It does not use any timestamp mechanism, but instead 44 processes queues in round-robin order. 45 46 ADVANTAGE: 47 48 - It is very cheap. Both CPU and memory requirements are minimal. 49 50 DRAWBACKS: 51 52 - "Stochastic" -> It is not 100% fair. 53 When hash collisions occur, several flows are considered as one. 54 55 - "Round-robin" -> It introduces larger delays than virtual clock 56 based schemes, and should not be used for isolating interactive 57 traffic from non-interactive. It means, that this scheduler 58 should be used as leaf of CBQ or P3, which put interactive traffic 59 to higher priority band. 60 61 We still need true WFQ for top level CSZ, but using WFQ 62 for the best effort traffic is absolutely pointless: 63 SFQ is superior for this purpose. 64 65 IMPLEMENTATION: 66 This implementation limits : 67 - maximal queue length per flow to 127 packets. 68 - max mtu to 2^18-1; 69 - max 65408 flows, 70 - number of hash buckets to 65536. 71 72 It is easy to increase these values, but not in flight. */ 73 74 #define SFQ_MAX_DEPTH 127 /* max number of packets per flow */ 75 #define SFQ_DEFAULT_FLOWS 128 76 #define SFQ_MAX_FLOWS (0x10000 - SFQ_MAX_DEPTH - 1) /* max number of flows */ 77 #define SFQ_EMPTY_SLOT 0xffff 78 #define SFQ_DEFAULT_HASH_DIVISOR 1024 79 80 /* This type should contain at least SFQ_MAX_DEPTH + 1 + SFQ_MAX_FLOWS values */ 81 typedef u16 sfq_index; 82 83 /* 84 * We dont use pointers to save space. 85 * Small indexes [0 ... SFQ_MAX_FLOWS - 1] are 'pointers' to slots[] array 86 * while following values [SFQ_MAX_FLOWS ... SFQ_MAX_FLOWS + SFQ_MAX_DEPTH] 87 * are 'pointers' to dep[] array 88 */ 89 struct sfq_head { 90 sfq_index next; 91 sfq_index prev; 92 }; 93 94 struct sfq_slot { 95 struct sk_buff *skblist_next; 96 struct sk_buff *skblist_prev; 97 sfq_index qlen; /* number of skbs in skblist */ 98 sfq_index next; /* next slot in sfq RR chain */ 99 struct sfq_head dep; /* anchor in dep[] chains */ 100 unsigned short hash; /* hash value (index in ht[]) */ 101 int allot; /* credit for this slot */ 102 103 unsigned int backlog; 104 struct red_vars vars; 105 }; 106 107 struct sfq_sched_data { 108 /* frequently used fields */ 109 int limit; /* limit of total number of packets in this qdisc */ 110 unsigned int divisor; /* number of slots in hash table */ 111 u8 headdrop; 112 u8 maxdepth; /* limit of packets per flow */ 113 114 siphash_key_t perturbation; 115 u8 cur_depth; /* depth of longest slot */ 116 u8 flags; 117 struct tcf_proto __rcu *filter_list; 118 struct tcf_block *block; 119 sfq_index *ht; /* Hash table ('divisor' slots) */ 120 struct sfq_slot *slots; /* Flows table ('maxflows' entries) */ 121 122 struct red_parms *red_parms; 123 struct tc_sfqred_stats stats; 124 struct sfq_slot *tail; /* current slot in round */ 125 126 struct sfq_head dep[SFQ_MAX_DEPTH + 1]; 127 /* Linked lists of slots, indexed by depth 128 * dep[0] : list of unused flows 129 * dep[1] : list of flows with 1 packet 130 * dep[X] : list of flows with X packets 131 */ 132 133 unsigned int maxflows; /* number of flows in flows array */ 134 int perturb_period; 135 unsigned int quantum; /* Allotment per round: MUST BE >= MTU */ 136 struct timer_list perturb_timer; 137 struct Qdisc *sch; 138 }; 139 140 /* 141 * sfq_head are either in a sfq_slot or in dep[] array 142 */ 143 static inline struct sfq_head *sfq_dep_head(struct sfq_sched_data *q, sfq_index val) 144 { 145 if (val < SFQ_MAX_FLOWS) 146 return &q->slots[val].dep; 147 return &q->dep[val - SFQ_MAX_FLOWS]; 148 } 149 150 static unsigned int sfq_hash(const struct sfq_sched_data *q, 151 const struct sk_buff *skb) 152 { 153 return skb_get_hash_perturb(skb, &q->perturbation) & (q->divisor - 1); 154 } 155 156 static unsigned int sfq_classify(struct sk_buff *skb, struct Qdisc *sch, 157 int *qerr) 158 { 159 struct sfq_sched_data *q = qdisc_priv(sch); 160 struct tcf_result res; 161 struct tcf_proto *fl; 162 int result; 163 164 if (TC_H_MAJ(skb->priority) == sch->handle && 165 TC_H_MIN(skb->priority) > 0 && 166 TC_H_MIN(skb->priority) <= q->divisor) 167 return TC_H_MIN(skb->priority); 168 169 fl = rcu_dereference_bh(q->filter_list); 170 if (!fl) 171 return sfq_hash(q, skb) + 1; 172 173 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; 174 result = tcf_classify(skb, NULL, fl, &res, false); 175 if (result >= 0) { 176 #ifdef CONFIG_NET_CLS_ACT 177 switch (result) { 178 case TC_ACT_STOLEN: 179 case TC_ACT_QUEUED: 180 case TC_ACT_TRAP: 181 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN; 182 fallthrough; 183 case TC_ACT_SHOT: 184 return 0; 185 } 186 #endif 187 if (TC_H_MIN(res.classid) <= q->divisor) 188 return TC_H_MIN(res.classid); 189 } 190 return 0; 191 } 192 193 /* 194 * x : slot number [0 .. SFQ_MAX_FLOWS - 1] 195 */ 196 static inline void sfq_link(struct sfq_sched_data *q, sfq_index x) 197 { 198 sfq_index p, n; 199 struct sfq_slot *slot = &q->slots[x]; 200 int qlen = slot->qlen; 201 202 p = qlen + SFQ_MAX_FLOWS; 203 n = q->dep[qlen].next; 204 205 slot->dep.next = n; 206 slot->dep.prev = p; 207 208 q->dep[qlen].next = x; /* sfq_dep_head(q, p)->next = x */ 209 sfq_dep_head(q, n)->prev = x; 210 } 211 212 #define sfq_unlink(q, x, n, p) \ 213 do { \ 214 n = q->slots[x].dep.next; \ 215 p = q->slots[x].dep.prev; \ 216 sfq_dep_head(q, p)->next = n; \ 217 sfq_dep_head(q, n)->prev = p; \ 218 } while (0) 219 220 221 static inline void sfq_dec(struct sfq_sched_data *q, sfq_index x) 222 { 223 sfq_index p, n; 224 int d; 225 226 sfq_unlink(q, x, n, p); 227 228 d = q->slots[x].qlen--; 229 if (n == p && q->cur_depth == d) 230 q->cur_depth--; 231 sfq_link(q, x); 232 } 233 234 static inline void sfq_inc(struct sfq_sched_data *q, sfq_index x) 235 { 236 sfq_index p, n; 237 int d; 238 239 sfq_unlink(q, x, n, p); 240 241 d = ++q->slots[x].qlen; 242 if (q->cur_depth < d) 243 q->cur_depth = d; 244 sfq_link(q, x); 245 } 246 247 /* helper functions : might be changed when/if skb use a standard list_head */ 248 249 /* remove one skb from tail of slot queue */ 250 static inline struct sk_buff *slot_dequeue_tail(struct sfq_slot *slot) 251 { 252 struct sk_buff *skb = slot->skblist_prev; 253 254 slot->skblist_prev = skb->prev; 255 skb->prev->next = (struct sk_buff *)slot; 256 skb->next = skb->prev = NULL; 257 return skb; 258 } 259 260 /* remove one skb from head of slot queue */ 261 static inline struct sk_buff *slot_dequeue_head(struct sfq_slot *slot) 262 { 263 struct sk_buff *skb = slot->skblist_next; 264 265 slot->skblist_next = skb->next; 266 skb->next->prev = (struct sk_buff *)slot; 267 skb->next = skb->prev = NULL; 268 return skb; 269 } 270 271 static inline void slot_queue_init(struct sfq_slot *slot) 272 { 273 memset(slot, 0, sizeof(*slot)); 274 slot->skblist_prev = slot->skblist_next = (struct sk_buff *)slot; 275 } 276 277 /* add skb to slot queue (tail add) */ 278 static inline void slot_queue_add(struct sfq_slot *slot, struct sk_buff *skb) 279 { 280 skb->prev = slot->skblist_prev; 281 skb->next = (struct sk_buff *)slot; 282 slot->skblist_prev->next = skb; 283 slot->skblist_prev = skb; 284 } 285 286 static unsigned int sfq_drop(struct Qdisc *sch, struct sk_buff **to_free) 287 { 288 struct sfq_sched_data *q = qdisc_priv(sch); 289 sfq_index x, d = q->cur_depth; 290 struct sk_buff *skb; 291 unsigned int len; 292 struct sfq_slot *slot; 293 294 /* Queue is full! Find the longest slot and drop tail packet from it */ 295 if (d > 1) { 296 x = q->dep[d].next; 297 slot = &q->slots[x]; 298 drop: 299 skb = q->headdrop ? slot_dequeue_head(slot) : slot_dequeue_tail(slot); 300 len = qdisc_pkt_len(skb); 301 slot->backlog -= len; 302 sfq_dec(q, x); 303 sch->q.qlen--; 304 qdisc_qstats_backlog_dec(sch, skb); 305 qdisc_drop(skb, sch, to_free); 306 return len; 307 } 308 309 if (d == 1) { 310 /* It is difficult to believe, but ALL THE SLOTS HAVE LENGTH 1. */ 311 x = q->tail->next; 312 slot = &q->slots[x]; 313 q->tail->next = slot->next; 314 q->ht[slot->hash] = SFQ_EMPTY_SLOT; 315 goto drop; 316 } 317 318 return 0; 319 } 320 321 /* Is ECN parameter configured */ 322 static int sfq_prob_mark(const struct sfq_sched_data *q) 323 { 324 return q->flags & TC_RED_ECN; 325 } 326 327 /* Should packets over max threshold just be marked */ 328 static int sfq_hard_mark(const struct sfq_sched_data *q) 329 { 330 return (q->flags & (TC_RED_ECN | TC_RED_HARDDROP)) == TC_RED_ECN; 331 } 332 333 static int sfq_headdrop(const struct sfq_sched_data *q) 334 { 335 return q->headdrop; 336 } 337 338 static int 339 sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free) 340 { 341 struct sfq_sched_data *q = qdisc_priv(sch); 342 unsigned int hash, dropped; 343 sfq_index x, qlen; 344 struct sfq_slot *slot; 345 int ret; 346 struct sk_buff *head; 347 int delta; 348 349 hash = sfq_classify(skb, sch, &ret); 350 if (hash == 0) { 351 if (ret & __NET_XMIT_BYPASS) 352 qdisc_qstats_drop(sch); 353 __qdisc_drop(skb, to_free); 354 return ret; 355 } 356 hash--; 357 358 x = q->ht[hash]; 359 slot = &q->slots[x]; 360 if (x == SFQ_EMPTY_SLOT) { 361 x = q->dep[0].next; /* get a free slot */ 362 if (x >= SFQ_MAX_FLOWS) 363 return qdisc_drop(skb, sch, to_free); 364 q->ht[hash] = x; 365 slot = &q->slots[x]; 366 slot->hash = hash; 367 slot->backlog = 0; /* should already be 0 anyway... */ 368 red_set_vars(&slot->vars); 369 goto enqueue; 370 } 371 if (q->red_parms) { 372 slot->vars.qavg = red_calc_qavg_no_idle_time(q->red_parms, 373 &slot->vars, 374 slot->backlog); 375 switch (red_action(q->red_parms, 376 &slot->vars, 377 slot->vars.qavg)) { 378 case RED_DONT_MARK: 379 break; 380 381 case RED_PROB_MARK: 382 qdisc_qstats_overlimit(sch); 383 if (sfq_prob_mark(q)) { 384 /* We know we have at least one packet in queue */ 385 if (sfq_headdrop(q) && 386 INET_ECN_set_ce(slot->skblist_next)) { 387 q->stats.prob_mark_head++; 388 break; 389 } 390 if (INET_ECN_set_ce(skb)) { 391 q->stats.prob_mark++; 392 break; 393 } 394 } 395 q->stats.prob_drop++; 396 goto congestion_drop; 397 398 case RED_HARD_MARK: 399 qdisc_qstats_overlimit(sch); 400 if (sfq_hard_mark(q)) { 401 /* We know we have at least one packet in queue */ 402 if (sfq_headdrop(q) && 403 INET_ECN_set_ce(slot->skblist_next)) { 404 q->stats.forced_mark_head++; 405 break; 406 } 407 if (INET_ECN_set_ce(skb)) { 408 q->stats.forced_mark++; 409 break; 410 } 411 } 412 q->stats.forced_drop++; 413 goto congestion_drop; 414 } 415 } 416 417 if (slot->qlen >= q->maxdepth) { 418 congestion_drop: 419 if (!sfq_headdrop(q)) 420 return qdisc_drop(skb, sch, to_free); 421 422 /* We know we have at least one packet in queue */ 423 head = slot_dequeue_head(slot); 424 delta = qdisc_pkt_len(head) - qdisc_pkt_len(skb); 425 sch->qstats.backlog -= delta; 426 slot->backlog -= delta; 427 qdisc_drop(head, sch, to_free); 428 429 slot_queue_add(slot, skb); 430 qdisc_tree_reduce_backlog(sch, 0, delta); 431 return NET_XMIT_CN; 432 } 433 434 enqueue: 435 qdisc_qstats_backlog_inc(sch, skb); 436 slot->backlog += qdisc_pkt_len(skb); 437 slot_queue_add(slot, skb); 438 sfq_inc(q, x); 439 if (slot->qlen == 1) { /* The flow is new */ 440 if (q->tail == NULL) { /* It is the first flow */ 441 slot->next = x; 442 } else { 443 slot->next = q->tail->next; 444 q->tail->next = x; 445 } 446 /* We put this flow at the end of our flow list. 447 * This might sound unfair for a new flow to wait after old ones, 448 * but we could endup servicing new flows only, and freeze old ones. 449 */ 450 q->tail = slot; 451 /* We could use a bigger initial quantum for new flows */ 452 slot->allot = q->quantum; 453 } 454 if (++sch->q.qlen <= q->limit) 455 return NET_XMIT_SUCCESS; 456 457 qlen = slot->qlen; 458 dropped = sfq_drop(sch, to_free); 459 /* Return Congestion Notification only if we dropped a packet 460 * from this flow. 461 */ 462 if (qlen != slot->qlen) { 463 qdisc_tree_reduce_backlog(sch, 0, dropped - qdisc_pkt_len(skb)); 464 return NET_XMIT_CN; 465 } 466 467 /* As we dropped a packet, better let upper stack know this */ 468 qdisc_tree_reduce_backlog(sch, 1, dropped); 469 return NET_XMIT_SUCCESS; 470 } 471 472 static struct sk_buff * 473 sfq_dequeue(struct Qdisc *sch) 474 { 475 struct sfq_sched_data *q = qdisc_priv(sch); 476 struct sk_buff *skb; 477 sfq_index a, next_a; 478 struct sfq_slot *slot; 479 480 /* No active slots */ 481 if (q->tail == NULL) 482 return NULL; 483 484 next_slot: 485 a = q->tail->next; 486 slot = &q->slots[a]; 487 if (slot->allot <= 0) { 488 q->tail = slot; 489 slot->allot += q->quantum; 490 goto next_slot; 491 } 492 skb = slot_dequeue_head(slot); 493 sfq_dec(q, a); 494 qdisc_bstats_update(sch, skb); 495 sch->q.qlen--; 496 qdisc_qstats_backlog_dec(sch, skb); 497 slot->backlog -= qdisc_pkt_len(skb); 498 /* Is the slot empty? */ 499 if (slot->qlen == 0) { 500 q->ht[slot->hash] = SFQ_EMPTY_SLOT; 501 next_a = slot->next; 502 if (a == next_a) { 503 q->tail = NULL; /* no more active slots */ 504 return skb; 505 } 506 q->tail->next = next_a; 507 } else { 508 slot->allot -= qdisc_pkt_len(skb); 509 } 510 return skb; 511 } 512 513 static void 514 sfq_reset(struct Qdisc *sch) 515 { 516 struct sk_buff *skb; 517 518 while ((skb = sfq_dequeue(sch)) != NULL) 519 rtnl_kfree_skbs(skb, skb); 520 } 521 522 /* 523 * When q->perturbation is changed, we rehash all queued skbs 524 * to avoid OOO (Out Of Order) effects. 525 * We dont use sfq_dequeue()/sfq_enqueue() because we dont want to change 526 * counters. 527 */ 528 static void sfq_rehash(struct Qdisc *sch) 529 { 530 struct sfq_sched_data *q = qdisc_priv(sch); 531 struct sk_buff *skb; 532 int i; 533 struct sfq_slot *slot; 534 struct sk_buff_head list; 535 int dropped = 0; 536 unsigned int drop_len = 0; 537 538 __skb_queue_head_init(&list); 539 540 for (i = 0; i < q->maxflows; i++) { 541 slot = &q->slots[i]; 542 if (!slot->qlen) 543 continue; 544 while (slot->qlen) { 545 skb = slot_dequeue_head(slot); 546 sfq_dec(q, i); 547 __skb_queue_tail(&list, skb); 548 } 549 slot->backlog = 0; 550 red_set_vars(&slot->vars); 551 q->ht[slot->hash] = SFQ_EMPTY_SLOT; 552 } 553 q->tail = NULL; 554 555 while ((skb = __skb_dequeue(&list)) != NULL) { 556 unsigned int hash = sfq_hash(q, skb); 557 sfq_index x = q->ht[hash]; 558 559 slot = &q->slots[x]; 560 if (x == SFQ_EMPTY_SLOT) { 561 x = q->dep[0].next; /* get a free slot */ 562 if (x >= SFQ_MAX_FLOWS) { 563 drop: 564 qdisc_qstats_backlog_dec(sch, skb); 565 drop_len += qdisc_pkt_len(skb); 566 kfree_skb(skb); 567 dropped++; 568 continue; 569 } 570 q->ht[hash] = x; 571 slot = &q->slots[x]; 572 slot->hash = hash; 573 } 574 if (slot->qlen >= q->maxdepth) 575 goto drop; 576 slot_queue_add(slot, skb); 577 if (q->red_parms) 578 slot->vars.qavg = red_calc_qavg(q->red_parms, 579 &slot->vars, 580 slot->backlog); 581 slot->backlog += qdisc_pkt_len(skb); 582 sfq_inc(q, x); 583 if (slot->qlen == 1) { /* The flow is new */ 584 if (q->tail == NULL) { /* It is the first flow */ 585 slot->next = x; 586 } else { 587 slot->next = q->tail->next; 588 q->tail->next = x; 589 } 590 q->tail = slot; 591 slot->allot = q->quantum; 592 } 593 } 594 sch->q.qlen -= dropped; 595 qdisc_tree_reduce_backlog(sch, dropped, drop_len); 596 } 597 598 static void sfq_perturbation(struct timer_list *t) 599 { 600 struct sfq_sched_data *q = from_timer(q, t, perturb_timer); 601 struct Qdisc *sch = q->sch; 602 spinlock_t *root_lock; 603 siphash_key_t nkey; 604 int period; 605 606 get_random_bytes(&nkey, sizeof(nkey)); 607 rcu_read_lock(); 608 root_lock = qdisc_lock(qdisc_root_sleeping(sch)); 609 spin_lock(root_lock); 610 q->perturbation = nkey; 611 if (!q->filter_list && q->tail) 612 sfq_rehash(sch); 613 spin_unlock(root_lock); 614 615 /* q->perturb_period can change under us from 616 * sfq_change() and sfq_destroy(). 617 */ 618 period = READ_ONCE(q->perturb_period); 619 if (period) 620 mod_timer(&q->perturb_timer, jiffies + period); 621 rcu_read_unlock(); 622 } 623 624 static int sfq_change(struct Qdisc *sch, struct nlattr *opt, 625 struct netlink_ext_ack *extack) 626 { 627 struct sfq_sched_data *q = qdisc_priv(sch); 628 struct tc_sfq_qopt *ctl = nla_data(opt); 629 struct tc_sfq_qopt_v1 *ctl_v1 = NULL; 630 unsigned int qlen, dropped = 0; 631 struct red_parms *p = NULL; 632 struct sk_buff *to_free = NULL; 633 struct sk_buff *tail = NULL; 634 635 if (opt->nla_len < nla_attr_size(sizeof(*ctl))) 636 return -EINVAL; 637 if (opt->nla_len >= nla_attr_size(sizeof(*ctl_v1))) 638 ctl_v1 = nla_data(opt); 639 if (ctl->divisor && 640 (!is_power_of_2(ctl->divisor) || ctl->divisor > 65536)) 641 return -EINVAL; 642 643 if ((int)ctl->quantum < 0) { 644 NL_SET_ERR_MSG_MOD(extack, "invalid quantum"); 645 return -EINVAL; 646 } 647 if (ctl_v1 && !red_check_params(ctl_v1->qth_min, ctl_v1->qth_max, 648 ctl_v1->Wlog, ctl_v1->Scell_log, NULL)) 649 return -EINVAL; 650 if (ctl_v1 && ctl_v1->qth_min) { 651 p = kmalloc(sizeof(*p), GFP_KERNEL); 652 if (!p) 653 return -ENOMEM; 654 } 655 sch_tree_lock(sch); 656 if (ctl->quantum) 657 q->quantum = ctl->quantum; 658 WRITE_ONCE(q->perturb_period, ctl->perturb_period * HZ); 659 if (ctl->flows) 660 q->maxflows = min_t(u32, ctl->flows, SFQ_MAX_FLOWS); 661 if (ctl->divisor) { 662 q->divisor = ctl->divisor; 663 q->maxflows = min_t(u32, q->maxflows, q->divisor); 664 } 665 if (ctl_v1) { 666 if (ctl_v1->depth) 667 q->maxdepth = min_t(u32, ctl_v1->depth, SFQ_MAX_DEPTH); 668 if (p) { 669 swap(q->red_parms, p); 670 red_set_parms(q->red_parms, 671 ctl_v1->qth_min, ctl_v1->qth_max, 672 ctl_v1->Wlog, 673 ctl_v1->Plog, ctl_v1->Scell_log, 674 NULL, 675 ctl_v1->max_P); 676 } 677 q->flags = ctl_v1->flags; 678 q->headdrop = ctl_v1->headdrop; 679 } 680 if (ctl->limit) { 681 q->limit = min_t(u32, ctl->limit, q->maxdepth * q->maxflows); 682 q->maxflows = min_t(u32, q->maxflows, q->limit); 683 } 684 685 qlen = sch->q.qlen; 686 while (sch->q.qlen > q->limit) { 687 dropped += sfq_drop(sch, &to_free); 688 if (!tail) 689 tail = to_free; 690 } 691 692 rtnl_kfree_skbs(to_free, tail); 693 qdisc_tree_reduce_backlog(sch, qlen - sch->q.qlen, dropped); 694 695 del_timer(&q->perturb_timer); 696 if (q->perturb_period) { 697 mod_timer(&q->perturb_timer, jiffies + q->perturb_period); 698 get_random_bytes(&q->perturbation, sizeof(q->perturbation)); 699 } 700 sch_tree_unlock(sch); 701 kfree(p); 702 return 0; 703 } 704 705 static void *sfq_alloc(size_t sz) 706 { 707 return kvmalloc(sz, GFP_KERNEL); 708 } 709 710 static void sfq_free(void *addr) 711 { 712 kvfree(addr); 713 } 714 715 static void sfq_destroy(struct Qdisc *sch) 716 { 717 struct sfq_sched_data *q = qdisc_priv(sch); 718 719 tcf_block_put(q->block); 720 WRITE_ONCE(q->perturb_period, 0); 721 del_timer_sync(&q->perturb_timer); 722 sfq_free(q->ht); 723 sfq_free(q->slots); 724 kfree(q->red_parms); 725 } 726 727 static int sfq_init(struct Qdisc *sch, struct nlattr *opt, 728 struct netlink_ext_ack *extack) 729 { 730 struct sfq_sched_data *q = qdisc_priv(sch); 731 int i; 732 int err; 733 734 q->sch = sch; 735 timer_setup(&q->perturb_timer, sfq_perturbation, TIMER_DEFERRABLE); 736 737 err = tcf_block_get(&q->block, &q->filter_list, sch, extack); 738 if (err) 739 return err; 740 741 for (i = 0; i < SFQ_MAX_DEPTH + 1; i++) { 742 q->dep[i].next = i + SFQ_MAX_FLOWS; 743 q->dep[i].prev = i + SFQ_MAX_FLOWS; 744 } 745 746 q->limit = SFQ_MAX_DEPTH; 747 q->maxdepth = SFQ_MAX_DEPTH; 748 q->cur_depth = 0; 749 q->tail = NULL; 750 q->divisor = SFQ_DEFAULT_HASH_DIVISOR; 751 q->maxflows = SFQ_DEFAULT_FLOWS; 752 q->quantum = psched_mtu(qdisc_dev(sch)); 753 q->perturb_period = 0; 754 get_random_bytes(&q->perturbation, sizeof(q->perturbation)); 755 756 if (opt) { 757 int err = sfq_change(sch, opt, extack); 758 if (err) 759 return err; 760 } 761 762 q->ht = sfq_alloc(sizeof(q->ht[0]) * q->divisor); 763 q->slots = sfq_alloc(sizeof(q->slots[0]) * q->maxflows); 764 if (!q->ht || !q->slots) { 765 /* Note: sfq_destroy() will be called by our caller */ 766 return -ENOMEM; 767 } 768 769 for (i = 0; i < q->divisor; i++) 770 q->ht[i] = SFQ_EMPTY_SLOT; 771 772 for (i = 0; i < q->maxflows; i++) { 773 slot_queue_init(&q->slots[i]); 774 sfq_link(q, i); 775 } 776 if (q->limit >= 1) 777 sch->flags |= TCQ_F_CAN_BYPASS; 778 else 779 sch->flags &= ~TCQ_F_CAN_BYPASS; 780 return 0; 781 } 782 783 static int sfq_dump(struct Qdisc *sch, struct sk_buff *skb) 784 { 785 struct sfq_sched_data *q = qdisc_priv(sch); 786 unsigned char *b = skb_tail_pointer(skb); 787 struct tc_sfq_qopt_v1 opt; 788 struct red_parms *p = q->red_parms; 789 790 memset(&opt, 0, sizeof(opt)); 791 opt.v0.quantum = q->quantum; 792 opt.v0.perturb_period = q->perturb_period / HZ; 793 opt.v0.limit = q->limit; 794 opt.v0.divisor = q->divisor; 795 opt.v0.flows = q->maxflows; 796 opt.depth = q->maxdepth; 797 opt.headdrop = q->headdrop; 798 799 if (p) { 800 opt.qth_min = p->qth_min >> p->Wlog; 801 opt.qth_max = p->qth_max >> p->Wlog; 802 opt.Wlog = p->Wlog; 803 opt.Plog = p->Plog; 804 opt.Scell_log = p->Scell_log; 805 opt.max_P = p->max_P; 806 } 807 memcpy(&opt.stats, &q->stats, sizeof(opt.stats)); 808 opt.flags = q->flags; 809 810 if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt)) 811 goto nla_put_failure; 812 813 return skb->len; 814 815 nla_put_failure: 816 nlmsg_trim(skb, b); 817 return -1; 818 } 819 820 static struct Qdisc *sfq_leaf(struct Qdisc *sch, unsigned long arg) 821 { 822 return NULL; 823 } 824 825 static unsigned long sfq_find(struct Qdisc *sch, u32 classid) 826 { 827 return 0; 828 } 829 830 static unsigned long sfq_bind(struct Qdisc *sch, unsigned long parent, 831 u32 classid) 832 { 833 return 0; 834 } 835 836 static void sfq_unbind(struct Qdisc *q, unsigned long cl) 837 { 838 } 839 840 static struct tcf_block *sfq_tcf_block(struct Qdisc *sch, unsigned long cl, 841 struct netlink_ext_ack *extack) 842 { 843 struct sfq_sched_data *q = qdisc_priv(sch); 844 845 if (cl) 846 return NULL; 847 return q->block; 848 } 849 850 static int sfq_dump_class(struct Qdisc *sch, unsigned long cl, 851 struct sk_buff *skb, struct tcmsg *tcm) 852 { 853 tcm->tcm_handle |= TC_H_MIN(cl); 854 return 0; 855 } 856 857 static int sfq_dump_class_stats(struct Qdisc *sch, unsigned long cl, 858 struct gnet_dump *d) 859 { 860 struct sfq_sched_data *q = qdisc_priv(sch); 861 sfq_index idx = q->ht[cl - 1]; 862 struct gnet_stats_queue qs = { 0 }; 863 struct tc_sfq_xstats xstats = { 0 }; 864 865 if (idx != SFQ_EMPTY_SLOT) { 866 const struct sfq_slot *slot = &q->slots[idx]; 867 868 xstats.allot = slot->allot; 869 qs.qlen = slot->qlen; 870 qs.backlog = slot->backlog; 871 } 872 if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0) 873 return -1; 874 return gnet_stats_copy_app(d, &xstats, sizeof(xstats)); 875 } 876 877 static void sfq_walk(struct Qdisc *sch, struct qdisc_walker *arg) 878 { 879 struct sfq_sched_data *q = qdisc_priv(sch); 880 unsigned int i; 881 882 if (arg->stop) 883 return; 884 885 for (i = 0; i < q->divisor; i++) { 886 if (q->ht[i] == SFQ_EMPTY_SLOT) { 887 arg->count++; 888 continue; 889 } 890 if (!tc_qdisc_stats_dump(sch, i + 1, arg)) 891 break; 892 } 893 } 894 895 static const struct Qdisc_class_ops sfq_class_ops = { 896 .leaf = sfq_leaf, 897 .find = sfq_find, 898 .tcf_block = sfq_tcf_block, 899 .bind_tcf = sfq_bind, 900 .unbind_tcf = sfq_unbind, 901 .dump = sfq_dump_class, 902 .dump_stats = sfq_dump_class_stats, 903 .walk = sfq_walk, 904 }; 905 906 static struct Qdisc_ops sfq_qdisc_ops __read_mostly = { 907 .cl_ops = &sfq_class_ops, 908 .id = "sfq", 909 .priv_size = sizeof(struct sfq_sched_data), 910 .enqueue = sfq_enqueue, 911 .dequeue = sfq_dequeue, 912 .peek = qdisc_peek_dequeued, 913 .init = sfq_init, 914 .reset = sfq_reset, 915 .destroy = sfq_destroy, 916 .change = NULL, 917 .dump = sfq_dump, 918 .owner = THIS_MODULE, 919 }; 920 MODULE_ALIAS_NET_SCH("sfq"); 921 922 static int __init sfq_module_init(void) 923 { 924 return register_qdisc(&sfq_qdisc_ops); 925 } 926 static void __exit sfq_module_exit(void) 927 { 928 unregister_qdisc(&sfq_qdisc_ops); 929 } 930 module_init(sfq_module_init) 931 module_exit(sfq_module_exit) 932 MODULE_LICENSE("GPL"); 933 MODULE_DESCRIPTION("Stochastic Fairness qdisc"); 934