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/* We use 16 bits to store allot, and want to handle packets up to 64K 81 * Scale allot by 8 (1<<3) so that no overflow occurs. 82 */ 83#define SFQ_ALLOT_SHIFT 3 84#define SFQ_ALLOT_SIZE(X) DIV_ROUND_UP(X, 1 << SFQ_ALLOT_SHIFT) 85 86/* This type should contain at least SFQ_MAX_DEPTH + 1 + SFQ_MAX_FLOWS values */ 87typedef u16 sfq_index; 88 89/* 90 * We dont use pointers to save space. 91 * Small indexes [0 ... SFQ_MAX_FLOWS - 1] are 'pointers' to slots[] array 92 * while following values [SFQ_MAX_FLOWS ... SFQ_MAX_FLOWS + SFQ_MAX_DEPTH] 93 * are 'pointers' to dep[] array 94 */ 95struct sfq_head { 96 sfq_index next; 97 sfq_index prev; 98}; 99 100struct sfq_slot { 101 struct sk_buff *skblist_next; 102 struct sk_buff *skblist_prev; 103 sfq_index qlen; /* number of skbs in skblist */ 104 sfq_index next; /* next slot in sfq RR chain */ 105 struct sfq_head dep; /* anchor in dep[] chains */ 106 unsigned short hash; /* hash value (index in ht[]) */ 107 short allot; /* credit for this slot */ 108 109 unsigned int backlog; 110 struct red_vars vars; 111}; 112 113struct sfq_sched_data { 114/* frequently used fields */ 115 int limit; /* limit of total number of packets in this qdisc */ 116 unsigned int divisor; /* number of slots in hash table */ 117 u8 headdrop; 118 u8 maxdepth; /* limit of packets per flow */ 119 120 siphash_key_t perturbation; 121 u8 cur_depth; /* depth of longest slot */ 122 u8 flags; 123 unsigned short scaled_quantum; /* SFQ_ALLOT_SIZE(quantum) */ 124 struct tcf_proto __rcu *filter_list; 125 struct tcf_block *block; 126 sfq_index *ht; /* Hash table ('divisor' slots) */ 127 struct sfq_slot *slots; /* Flows table ('maxflows' entries) */ 128 129 struct red_parms *red_parms; 130 struct tc_sfqred_stats stats; 131 struct sfq_slot *tail; /* current slot in round */ 132 133 struct sfq_head dep[SFQ_MAX_DEPTH + 1]; 134 /* Linked lists of slots, indexed by depth 135 * dep[0] : list of unused flows 136 * dep[1] : list of flows with 1 packet 137 * dep[X] : list of flows with X packets 138 */ 139 140 unsigned int maxflows; /* number of flows in flows array */ 141 int perturb_period; 142 unsigned int quantum; /* Allotment per round: MUST BE >= MTU */ 143 struct timer_list perturb_timer; 144 struct Qdisc *sch; 145}; 146 147/* 148 * sfq_head are either in a sfq_slot or in dep[] array 149 */ 150static inline struct sfq_head *sfq_dep_head(struct sfq_sched_data *q, sfq_index val) 151{ 152 if (val < SFQ_MAX_FLOWS) 153 return &q->slots[val].dep; 154 return &q->dep[val - SFQ_MAX_FLOWS]; 155} 156 157static unsigned int sfq_hash(const struct sfq_sched_data *q, 158 const struct sk_buff *skb) 159{ 160 return skb_get_hash_perturb(skb, &q->perturbation) & (q->divisor - 1); 161} 162 163static unsigned int sfq_classify(struct sk_buff *skb, struct Qdisc *sch, 164 int *qerr) 165{ 166 struct sfq_sched_data *q = qdisc_priv(sch); 167 struct tcf_result res; 168 struct tcf_proto *fl; 169 int result; 170 171 if (TC_H_MAJ(skb->priority) == sch->handle && 172 TC_H_MIN(skb->priority) > 0 && 173 TC_H_MIN(skb->priority) <= q->divisor) 174 return TC_H_MIN(skb->priority); 175 176 fl = rcu_dereference_bh(q->filter_list); 177 if (!fl) 178 return sfq_hash(q, skb) + 1; 179 180 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; 181 result = tcf_classify(skb, NULL, fl, &res, false); 182 if (result >= 0) { 183#ifdef CONFIG_NET_CLS_ACT 184 switch (result) { 185 case TC_ACT_STOLEN: 186 case TC_ACT_QUEUED: 187 case TC_ACT_TRAP: 188 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN; 189 fallthrough; 190 case TC_ACT_SHOT: 191 return 0; 192 } 193#endif 194 if (TC_H_MIN(res.classid) <= q->divisor) 195 return TC_H_MIN(res.classid); 196 } 197 return 0; 198} 199 200/* 201 * x : slot number [0 .. SFQ_MAX_FLOWS - 1] 202 */ 203static inline void sfq_link(struct sfq_sched_data *q, sfq_index x) 204{ 205 sfq_index p, n; 206 struct sfq_slot *slot = &q->slots[x]; 207 int qlen = slot->qlen; 208 209 p = qlen + SFQ_MAX_FLOWS; 210 n = q->dep[qlen].next; 211 212 slot->dep.next = n; 213 slot->dep.prev = p; 214 215 q->dep[qlen].next = x; /* sfq_dep_head(q, p)->next = x */ 216 sfq_dep_head(q, n)->prev = x; 217} 218 219#define sfq_unlink(q, x, n, p) \ 220 do { \ 221 n = q->slots[x].dep.next; \ 222 p = q->slots[x].dep.prev; \ 223 sfq_dep_head(q, p)->next = n; \ 224 sfq_dep_head(q, n)->prev = p; \ 225 } while (0) 226 227 228static inline void sfq_dec(struct sfq_sched_data *q, sfq_index x) 229{ 230 sfq_index p, n; 231 int d; 232 233 sfq_unlink(q, x, n, p); 234 235 d = q->slots[x].qlen--; 236 if (n == p && q->cur_depth == d) 237 q->cur_depth--; 238 sfq_link(q, x); 239} 240 241static inline void sfq_inc(struct sfq_sched_data *q, sfq_index x) 242{ 243 sfq_index p, n; 244 int d; 245 246 sfq_unlink(q, x, n, p); 247 248 d = ++q->slots[x].qlen; 249 if (q->cur_depth < d) 250 q->cur_depth = d; 251 sfq_link(q, x); 252} 253 254/* helper functions : might be changed when/if skb use a standard list_head */ 255 256/* remove one skb from tail of slot queue */ 257static inline struct sk_buff *slot_dequeue_tail(struct sfq_slot *slot) 258{ 259 struct sk_buff *skb = slot->skblist_prev; 260 261 slot->skblist_prev = skb->prev; 262 skb->prev->next = (struct sk_buff *)slot; 263 skb->next = skb->prev = NULL; 264 return skb; 265} 266 267/* remove one skb from head of slot queue */ 268static inline struct sk_buff *slot_dequeue_head(struct sfq_slot *slot) 269{ 270 struct sk_buff *skb = slot->skblist_next; 271 272 slot->skblist_next = skb->next; 273 skb->next->prev = (struct sk_buff *)slot; 274 skb->next = skb->prev = NULL; 275 return skb; 276} 277 278static inline void slot_queue_init(struct sfq_slot *slot) 279{ 280 memset(slot, 0, sizeof(*slot)); 281 slot->skblist_prev = slot->skblist_next = (struct sk_buff *)slot; 282} 283 284/* add skb to slot queue (tail add) */ 285static inline void slot_queue_add(struct sfq_slot *slot, struct sk_buff *skb) 286{ 287 skb->prev = slot->skblist_prev; 288 skb->next = (struct sk_buff *)slot; 289 slot->skblist_prev->next = skb; 290 slot->skblist_prev = skb; 291} 292 293static unsigned int sfq_drop(struct Qdisc *sch, struct sk_buff **to_free) 294{ 295 struct sfq_sched_data *q = qdisc_priv(sch); 296 sfq_index x, d = q->cur_depth; 297 struct sk_buff *skb; 298 unsigned int len; 299 struct sfq_slot *slot; 300 301 /* Queue is full! Find the longest slot and drop tail packet from it */ 302 if (d > 1) { 303 x = q->dep[d].next; 304 slot = &q->slots[x]; 305drop: 306 skb = q->headdrop ? slot_dequeue_head(slot) : slot_dequeue_tail(slot); 307 len = qdisc_pkt_len(skb); 308 slot->backlog -= len; 309 sfq_dec(q, x); 310 sch->q.qlen--; 311 qdisc_qstats_backlog_dec(sch, skb); 312 qdisc_drop(skb, sch, to_free); 313 return len; 314 } 315 316 if (d == 1) { 317 /* It is difficult to believe, but ALL THE SLOTS HAVE LENGTH 1. */ 318 x = q->tail->next; 319 slot = &q->slots[x]; 320 q->tail->next = slot->next; 321 q->ht[slot->hash] = SFQ_EMPTY_SLOT; 322 goto drop; 323 } 324 325 return 0; 326} 327 328/* Is ECN parameter configured */ 329static int sfq_prob_mark(const struct sfq_sched_data *q) 330{ 331 return q->flags & TC_RED_ECN; 332} 333 334/* Should packets over max threshold just be marked */ 335static int sfq_hard_mark(const struct sfq_sched_data *q) 336{ 337 return (q->flags & (TC_RED_ECN | TC_RED_HARDDROP)) == TC_RED_ECN; 338} 339 340static int sfq_headdrop(const struct sfq_sched_data *q) 341{ 342 return q->headdrop; 343} 344 345static int 346sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free) 347{ 348 struct sfq_sched_data *q = qdisc_priv(sch); 349 unsigned int hash, dropped; 350 sfq_index x, qlen; 351 struct sfq_slot *slot; 352 int ret; 353 struct sk_buff *head; 354 int delta; 355 356 hash = sfq_classify(skb, sch, &ret); 357 if (hash == 0) { 358 if (ret & __NET_XMIT_BYPASS) 359 qdisc_qstats_drop(sch); 360 __qdisc_drop(skb, to_free); 361 return ret; 362 } 363 hash--; 364 365 x = q->ht[hash]; 366 slot = &q->slots[x]; 367 if (x == SFQ_EMPTY_SLOT) { 368 x = q->dep[0].next; /* get a free slot */ 369 if (x >= SFQ_MAX_FLOWS) 370 return qdisc_drop(skb, sch, to_free); 371 q->ht[hash] = x; 372 slot = &q->slots[x]; 373 slot->hash = hash; 374 slot->backlog = 0; /* should already be 0 anyway... */ 375 red_set_vars(&slot->vars); 376 goto enqueue; 377 } 378 if (q->red_parms) { 379 slot->vars.qavg = red_calc_qavg_no_idle_time(q->red_parms, 380 &slot->vars, 381 slot->backlog); 382 switch (red_action(q->red_parms, 383 &slot->vars, 384 slot->vars.qavg)) { 385 case RED_DONT_MARK: 386 break; 387 388 case RED_PROB_MARK: 389 qdisc_qstats_overlimit(sch); 390 if (sfq_prob_mark(q)) { 391 /* We know we have at least one packet in queue */ 392 if (sfq_headdrop(q) && 393 INET_ECN_set_ce(slot->skblist_next)) { 394 q->stats.prob_mark_head++; 395 break; 396 } 397 if (INET_ECN_set_ce(skb)) { 398 q->stats.prob_mark++; 399 break; 400 } 401 } 402 q->stats.prob_drop++; 403 goto congestion_drop; 404 405 case RED_HARD_MARK: 406 qdisc_qstats_overlimit(sch); 407 if (sfq_hard_mark(q)) { 408 /* We know we have at least one packet in queue */ 409 if (sfq_headdrop(q) && 410 INET_ECN_set_ce(slot->skblist_next)) { 411 q->stats.forced_mark_head++; 412 break; 413 } 414 if (INET_ECN_set_ce(skb)) { 415 q->stats.forced_mark++; 416 break; 417 } 418 } 419 q->stats.forced_drop++; 420 goto congestion_drop; 421 } 422 } 423 424 if (slot->qlen >= q->maxdepth) { 425congestion_drop: 426 if (!sfq_headdrop(q)) 427 return qdisc_drop(skb, sch, to_free); 428 429 /* We know we have at least one packet in queue */ 430 head = slot_dequeue_head(slot); 431 delta = qdisc_pkt_len(head) - qdisc_pkt_len(skb); 432 sch->qstats.backlog -= delta; 433 slot->backlog -= delta; 434 qdisc_drop(head, sch, to_free); 435 436 slot_queue_add(slot, skb); 437 qdisc_tree_reduce_backlog(sch, 0, delta); 438 return NET_XMIT_CN; 439 } 440 441enqueue: 442 qdisc_qstats_backlog_inc(sch, skb); 443 slot->backlog += qdisc_pkt_len(skb); 444 slot_queue_add(slot, skb); 445 sfq_inc(q, x); 446 if (slot->qlen == 1) { /* The flow is new */ 447 if (q->tail == NULL) { /* It is the first flow */ 448 slot->next = x; 449 } else { 450 slot->next = q->tail->next; 451 q->tail->next = x; 452 } 453 /* We put this flow at the end of our flow list. 454 * This might sound unfair for a new flow to wait after old ones, 455 * but we could endup servicing new flows only, and freeze old ones. 456 */ 457 q->tail = slot; 458 /* We could use a bigger initial quantum for new flows */ 459 slot->allot = q->scaled_quantum; 460 } 461 if (++sch->q.qlen <= q->limit) 462 return NET_XMIT_SUCCESS; 463 464 qlen = slot->qlen; 465 dropped = sfq_drop(sch, to_free); 466 /* Return Congestion Notification only if we dropped a packet 467 * from this flow. 468 */ 469 if (qlen != slot->qlen) { 470 qdisc_tree_reduce_backlog(sch, 0, dropped - qdisc_pkt_len(skb)); 471 return NET_XMIT_CN; 472 } 473 474 /* As we dropped a packet, better let upper stack know this */ 475 qdisc_tree_reduce_backlog(sch, 1, dropped); 476 return NET_XMIT_SUCCESS; 477} 478 479static struct sk_buff * 480sfq_dequeue(struct Qdisc *sch) 481{ 482 struct sfq_sched_data *q = qdisc_priv(sch); 483 struct sk_buff *skb; 484 sfq_index a, next_a; 485 struct sfq_slot *slot; 486 487 /* No active slots */ 488 if (q->tail == NULL) 489 return NULL; 490 491next_slot: 492 a = q->tail->next; 493 slot = &q->slots[a]; 494 if (slot->allot <= 0) { 495 q->tail = slot; 496 slot->allot += q->scaled_quantum; 497 goto next_slot; 498 } 499 skb = slot_dequeue_head(slot); 500 sfq_dec(q, a); 501 qdisc_bstats_update(sch, skb); 502 sch->q.qlen--; 503 qdisc_qstats_backlog_dec(sch, skb); 504 slot->backlog -= qdisc_pkt_len(skb); 505 /* Is the slot empty? */ 506 if (slot->qlen == 0) { 507 q->ht[slot->hash] = SFQ_EMPTY_SLOT; 508 next_a = slot->next; 509 if (a == next_a) { 510 q->tail = NULL; /* no more active slots */ 511 return skb; 512 } 513 q->tail->next = next_a; 514 } else { 515 slot->allot -= SFQ_ALLOT_SIZE(qdisc_pkt_len(skb)); 516 } 517 return skb; 518} 519 520static void 521sfq_reset(struct Qdisc *sch) 522{ 523 struct sk_buff *skb; 524 525 while ((skb = sfq_dequeue(sch)) != NULL) 526 rtnl_kfree_skbs(skb, skb); 527} 528 529/* 530 * When q->perturbation is changed, we rehash all queued skbs 531 * to avoid OOO (Out Of Order) effects. 532 * We dont use sfq_dequeue()/sfq_enqueue() because we dont want to change 533 * counters. 534 */ 535static void sfq_rehash(struct Qdisc *sch) 536{ 537 struct sfq_sched_data *q = qdisc_priv(sch); 538 struct sk_buff *skb; 539 int i; 540 struct sfq_slot *slot; 541 struct sk_buff_head list; 542 int dropped = 0; 543 unsigned int drop_len = 0; 544 545 __skb_queue_head_init(&list); 546 547 for (i = 0; i < q->maxflows; i++) { 548 slot = &q->slots[i]; 549 if (!slot->qlen) 550 continue; 551 while (slot->qlen) { 552 skb = slot_dequeue_head(slot); 553 sfq_dec(q, i); 554 __skb_queue_tail(&list, skb); 555 } 556 slot->backlog = 0; 557 red_set_vars(&slot->vars); 558 q->ht[slot->hash] = SFQ_EMPTY_SLOT; 559 } 560 q->tail = NULL; 561 562 while ((skb = __skb_dequeue(&list)) != NULL) { 563 unsigned int hash = sfq_hash(q, skb); 564 sfq_index x = q->ht[hash]; 565 566 slot = &q->slots[x]; 567 if (x == SFQ_EMPTY_SLOT) { 568 x = q->dep[0].next; /* get a free slot */ 569 if (x >= SFQ_MAX_FLOWS) { 570drop: 571 qdisc_qstats_backlog_dec(sch, skb); 572 drop_len += qdisc_pkt_len(skb); 573 kfree_skb(skb); 574 dropped++; 575 continue; 576 } 577 q->ht[hash] = x; 578 slot = &q->slots[x]; 579 slot->hash = hash; 580 } 581 if (slot->qlen >= q->maxdepth) 582 goto drop; 583 slot_queue_add(slot, skb); 584 if (q->red_parms) 585 slot->vars.qavg = red_calc_qavg(q->red_parms, 586 &slot->vars, 587 slot->backlog); 588 slot->backlog += qdisc_pkt_len(skb); 589 sfq_inc(q, x); 590 if (slot->qlen == 1) { /* The flow is new */ 591 if (q->tail == NULL) { /* It is the first flow */ 592 slot->next = x; 593 } else { 594 slot->next = q->tail->next; 595 q->tail->next = x; 596 } 597 q->tail = slot; 598 slot->allot = q->scaled_quantum; 599 } 600 } 601 sch->q.qlen -= dropped; 602 qdisc_tree_reduce_backlog(sch, dropped, drop_len); 603} 604 605static void sfq_perturbation(struct timer_list *t) 606{ 607 struct sfq_sched_data *q = from_timer(q, t, perturb_timer); 608 struct Qdisc *sch = q->sch; 609 spinlock_t *root_lock; 610 siphash_key_t nkey; 611 612 get_random_bytes(&nkey, sizeof(nkey)); 613 rcu_read_lock(); 614 root_lock = qdisc_lock(qdisc_root_sleeping(sch)); 615 spin_lock(root_lock); 616 q->perturbation = nkey; 617 if (!q->filter_list && q->tail) 618 sfq_rehash(sch); 619 spin_unlock(root_lock); 620 621 if (q->perturb_period) 622 mod_timer(&q->perturb_timer, jiffies + q->perturb_period); 623 rcu_read_unlock(); 624} 625 626static int sfq_change(struct Qdisc *sch, struct nlattr *opt) 627{ 628 struct sfq_sched_data *q = qdisc_priv(sch); 629 struct tc_sfq_qopt *ctl = nla_data(opt); 630 struct tc_sfq_qopt_v1 *ctl_v1 = NULL; 631 unsigned int qlen, dropped = 0; 632 struct red_parms *p = NULL; 633 struct sk_buff *to_free = NULL; 634 struct sk_buff *tail = NULL; 635 636 if (opt->nla_len < nla_attr_size(sizeof(*ctl))) 637 return -EINVAL; 638 if (opt->nla_len >= nla_attr_size(sizeof(*ctl_v1))) 639 ctl_v1 = nla_data(opt); 640 if (ctl->divisor && 641 (!is_power_of_2(ctl->divisor) || ctl->divisor > 65536)) 642 return -EINVAL; 643 644 /* slot->allot is a short, make sure quantum is not too big. */ 645 if (ctl->quantum) { 646 unsigned int scaled = SFQ_ALLOT_SIZE(ctl->quantum); 647 648 if (scaled <= 0 || scaled > SHRT_MAX) 649 return -EINVAL; 650 } 651 652 if (ctl_v1 && !red_check_params(ctl_v1->qth_min, ctl_v1->qth_max, 653 ctl_v1->Wlog, ctl_v1->Scell_log, NULL)) 654 return -EINVAL; 655 if (ctl_v1 && ctl_v1->qth_min) { 656 p = kmalloc(sizeof(*p), GFP_KERNEL); 657 if (!p) 658 return -ENOMEM; 659 } 660 sch_tree_lock(sch); 661 if (ctl->quantum) { 662 q->quantum = ctl->quantum; 663 q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum); 664 } 665 q->perturb_period = ctl->perturb_period * HZ; 666 if (ctl->flows) 667 q->maxflows = min_t(u32, ctl->flows, SFQ_MAX_FLOWS); 668 if (ctl->divisor) { 669 q->divisor = ctl->divisor; 670 q->maxflows = min_t(u32, q->maxflows, q->divisor); 671 } 672 if (ctl_v1) { 673 if (ctl_v1->depth) 674 q->maxdepth = min_t(u32, ctl_v1->depth, SFQ_MAX_DEPTH); 675 if (p) { 676 swap(q->red_parms, p); 677 red_set_parms(q->red_parms, 678 ctl_v1->qth_min, ctl_v1->qth_max, 679 ctl_v1->Wlog, 680 ctl_v1->Plog, ctl_v1->Scell_log, 681 NULL, 682 ctl_v1->max_P); 683 } 684 q->flags = ctl_v1->flags; 685 q->headdrop = ctl_v1->headdrop; 686 } 687 if (ctl->limit) { 688 q->limit = min_t(u32, ctl->limit, q->maxdepth * q->maxflows); 689 q->maxflows = min_t(u32, q->maxflows, q->limit); 690 } 691 692 qlen = sch->q.qlen; 693 while (sch->q.qlen > q->limit) { 694 dropped += sfq_drop(sch, &to_free); 695 if (!tail) 696 tail = to_free; 697 } 698 699 rtnl_kfree_skbs(to_free, tail); 700 qdisc_tree_reduce_backlog(sch, qlen - sch->q.qlen, dropped); 701 702 del_timer(&q->perturb_timer); 703 if (q->perturb_period) { 704 mod_timer(&q->perturb_timer, jiffies + q->perturb_period); 705 get_random_bytes(&q->perturbation, sizeof(q->perturbation)); 706 } 707 sch_tree_unlock(sch); 708 kfree(p); 709 return 0; 710} 711 712static void *sfq_alloc(size_t sz) 713{ 714 return kvmalloc(sz, GFP_KERNEL); 715} 716 717static void sfq_free(void *addr) 718{ 719 kvfree(addr); 720} 721 722static void sfq_destroy(struct Qdisc *sch) 723{ 724 struct sfq_sched_data *q = qdisc_priv(sch); 725 726 tcf_block_put(q->block); 727 q->perturb_period = 0; 728 del_timer_sync(&q->perturb_timer); 729 sfq_free(q->ht); 730 sfq_free(q->slots); 731 kfree(q->red_parms); 732} 733 734static int sfq_init(struct Qdisc *sch, struct nlattr *opt, 735 struct netlink_ext_ack *extack) 736{ 737 struct sfq_sched_data *q = qdisc_priv(sch); 738 int i; 739 int err; 740 741 q->sch = sch; 742 timer_setup(&q->perturb_timer, sfq_perturbation, TIMER_DEFERRABLE); 743 744 err = tcf_block_get(&q->block, &q->filter_list, sch, extack); 745 if (err) 746 return err; 747 748 for (i = 0; i < SFQ_MAX_DEPTH + 1; i++) { 749 q->dep[i].next = i + SFQ_MAX_FLOWS; 750 q->dep[i].prev = i + SFQ_MAX_FLOWS; 751 } 752 753 q->limit = SFQ_MAX_DEPTH; 754 q->maxdepth = SFQ_MAX_DEPTH; 755 q->cur_depth = 0; 756 q->tail = NULL; 757 q->divisor = SFQ_DEFAULT_HASH_DIVISOR; 758 q->maxflows = SFQ_DEFAULT_FLOWS; 759 q->quantum = psched_mtu(qdisc_dev(sch)); 760 q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum); 761 q->perturb_period = 0; 762 get_random_bytes(&q->perturbation, sizeof(q->perturbation)); 763 764 if (opt) { 765 int err = sfq_change(sch, opt); 766 if (err) 767 return err; 768 } 769 770 q->ht = sfq_alloc(sizeof(q->ht[0]) * q->divisor); 771 q->slots = sfq_alloc(sizeof(q->slots[0]) * q->maxflows); 772 if (!q->ht || !q->slots) { 773 /* Note: sfq_destroy() will be called by our caller */ 774 return -ENOMEM; 775 } 776 777 for (i = 0; i < q->divisor; i++) 778 q->ht[i] = SFQ_EMPTY_SLOT; 779 780 for (i = 0; i < q->maxflows; i++) { 781 slot_queue_init(&q->slots[i]); 782 sfq_link(q, i); 783 } 784 if (q->limit >= 1) 785 sch->flags |= TCQ_F_CAN_BYPASS; 786 else 787 sch->flags &= ~TCQ_F_CAN_BYPASS; 788 return 0; 789} 790 791static int sfq_dump(struct Qdisc *sch, struct sk_buff *skb) 792{ 793 struct sfq_sched_data *q = qdisc_priv(sch); 794 unsigned char *b = skb_tail_pointer(skb); 795 struct tc_sfq_qopt_v1 opt; 796 struct red_parms *p = q->red_parms; 797 798 memset(&opt, 0, sizeof(opt)); 799 opt.v0.quantum = q->quantum; 800 opt.v0.perturb_period = q->perturb_period / HZ; 801 opt.v0.limit = q->limit; 802 opt.v0.divisor = q->divisor; 803 opt.v0.flows = q->maxflows; 804 opt.depth = q->maxdepth; 805 opt.headdrop = q->headdrop; 806 807 if (p) { 808 opt.qth_min = p->qth_min >> p->Wlog; 809 opt.qth_max = p->qth_max >> p->Wlog; 810 opt.Wlog = p->Wlog; 811 opt.Plog = p->Plog; 812 opt.Scell_log = p->Scell_log; 813 opt.max_P = p->max_P; 814 } 815 memcpy(&opt.stats, &q->stats, sizeof(opt.stats)); 816 opt.flags = q->flags; 817 818 if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt)) 819 goto nla_put_failure; 820 821 return skb->len; 822 823nla_put_failure: 824 nlmsg_trim(skb, b); 825 return -1; 826} 827 828static struct Qdisc *sfq_leaf(struct Qdisc *sch, unsigned long arg) 829{ 830 return NULL; 831} 832 833static unsigned long sfq_find(struct Qdisc *sch, u32 classid) 834{ 835 return 0; 836} 837 838static unsigned long sfq_bind(struct Qdisc *sch, unsigned long parent, 839 u32 classid) 840{ 841 return 0; 842} 843 844static void sfq_unbind(struct Qdisc *q, unsigned long cl) 845{ 846} 847 848static struct tcf_block *sfq_tcf_block(struct Qdisc *sch, unsigned long cl, 849 struct netlink_ext_ack *extack) 850{ 851 struct sfq_sched_data *q = qdisc_priv(sch); 852 853 if (cl) 854 return NULL; 855 return q->block; 856} 857 858static int sfq_dump_class(struct Qdisc *sch, unsigned long cl, 859 struct sk_buff *skb, struct tcmsg *tcm) 860{ 861 tcm->tcm_handle |= TC_H_MIN(cl); 862 return 0; 863} 864 865static int sfq_dump_class_stats(struct Qdisc *sch, unsigned long cl, 866 struct gnet_dump *d) 867{ 868 struct sfq_sched_data *q = qdisc_priv(sch); 869 sfq_index idx = q->ht[cl - 1]; 870 struct gnet_stats_queue qs = { 0 }; 871 struct tc_sfq_xstats xstats = { 0 }; 872 873 if (idx != SFQ_EMPTY_SLOT) { 874 const struct sfq_slot *slot = &q->slots[idx]; 875 876 xstats.allot = slot->allot << SFQ_ALLOT_SHIFT; 877 qs.qlen = slot->qlen; 878 qs.backlog = slot->backlog; 879 } 880 if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0) 881 return -1; 882 return gnet_stats_copy_app(d, &xstats, sizeof(xstats)); 883} 884 885static void sfq_walk(struct Qdisc *sch, struct qdisc_walker *arg) 886{ 887 struct sfq_sched_data *q = qdisc_priv(sch); 888 unsigned int i; 889 890 if (arg->stop) 891 return; 892 893 for (i = 0; i < q->divisor; i++) { 894 if (q->ht[i] == SFQ_EMPTY_SLOT) { 895 arg->count++; 896 continue; 897 } 898 if (!tc_qdisc_stats_dump(sch, i + 1, arg)) 899 break; 900 } 901} 902 903static const struct Qdisc_class_ops sfq_class_ops = { 904 .leaf = sfq_leaf, 905 .find = sfq_find, 906 .tcf_block = sfq_tcf_block, 907 .bind_tcf = sfq_bind, 908 .unbind_tcf = sfq_unbind, 909 .dump = sfq_dump_class, 910 .dump_stats = sfq_dump_class_stats, 911 .walk = sfq_walk, 912}; 913 914static struct Qdisc_ops sfq_qdisc_ops __read_mostly = { 915 .cl_ops = &sfq_class_ops, 916 .id = "sfq", 917 .priv_size = sizeof(struct sfq_sched_data), 918 .enqueue = sfq_enqueue, 919 .dequeue = sfq_dequeue, 920 .peek = qdisc_peek_dequeued, 921 .init = sfq_init, 922 .reset = sfq_reset, 923 .destroy = sfq_destroy, 924 .change = NULL, 925 .dump = sfq_dump, 926 .owner = THIS_MODULE, 927}; 928MODULE_ALIAS_NET_SCH("sfq"); 929 930static int __init sfq_module_init(void) 931{ 932 return register_qdisc(&sfq_qdisc_ops); 933} 934static void __exit sfq_module_exit(void) 935{ 936 unregister_qdisc(&sfq_qdisc_ops); 937} 938module_init(sfq_module_init) 939module_exit(sfq_module_exit) 940MODULE_LICENSE("GPL"); 941MODULE_DESCRIPTION("Stochastic Fairness qdisc"); 942