1 /* 2 * net/sched/sch_sfq.c Stochastic Fairness Queueing discipline. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 7 * 2 of the License, or (at your option) any later version. 8 * 9 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> 10 */ 11 12 #include <linux/module.h> 13 #include <linux/types.h> 14 #include <linux/kernel.h> 15 #include <linux/jiffies.h> 16 #include <linux/string.h> 17 #include <linux/in.h> 18 #include <linux/errno.h> 19 #include <linux/init.h> 20 #include <linux/ipv6.h> 21 #include <linux/skbuff.h> 22 #include <linux/jhash.h> 23 #include <linux/slab.h> 24 #include <linux/vmalloc.h> 25 #include <net/ip.h> 26 #include <net/netlink.h> 27 #include <net/pkt_sched.h> 28 29 30 /* Stochastic Fairness Queuing algorithm. 31 ======================================= 32 33 Source: 34 Paul E. McKenney "Stochastic Fairness Queuing", 35 IEEE INFOCOMM'90 Proceedings, San Francisco, 1990. 36 37 Paul E. McKenney "Stochastic Fairness Queuing", 38 "Interworking: Research and Experience", v.2, 1991, p.113-131. 39 40 41 See also: 42 M. Shreedhar and George Varghese "Efficient Fair 43 Queuing using Deficit Round Robin", Proc. SIGCOMM 95. 44 45 46 This is not the thing that is usually called (W)FQ nowadays. 47 It does not use any timestamp mechanism, but instead 48 processes queues in round-robin order. 49 50 ADVANTAGE: 51 52 - It is very cheap. Both CPU and memory requirements are minimal. 53 54 DRAWBACKS: 55 56 - "Stochastic" -> It is not 100% fair. 57 When hash collisions occur, several flows are considered as one. 58 59 - "Round-robin" -> It introduces larger delays than virtual clock 60 based schemes, and should not be used for isolating interactive 61 traffic from non-interactive. It means, that this scheduler 62 should be used as leaf of CBQ or P3, which put interactive traffic 63 to higher priority band. 64 65 We still need true WFQ for top level CSZ, but using WFQ 66 for the best effort traffic is absolutely pointless: 67 SFQ is superior for this purpose. 68 69 IMPLEMENTATION: 70 This implementation limits maximal queue length to 128; 71 max mtu to 2^18-1; max 128 flows, number of hash buckets to 1024. 72 The only goal of this restrictions was that all data 73 fit into one 4K page on 32bit arches. 74 75 It is easy to increase these values, but not in flight. */ 76 77 #define SFQ_DEPTH 128 /* max number of packets per flow */ 78 #define SFQ_SLOTS 128 /* max number of flows */ 79 #define SFQ_EMPTY_SLOT 255 80 #define SFQ_DEFAULT_HASH_DIVISOR 1024 81 82 /* We use 16 bits to store allot, and want to handle packets up to 64K 83 * Scale allot by 8 (1<<3) so that no overflow occurs. 84 */ 85 #define SFQ_ALLOT_SHIFT 3 86 #define SFQ_ALLOT_SIZE(X) DIV_ROUND_UP(X, 1 << SFQ_ALLOT_SHIFT) 87 88 /* This type should contain at least SFQ_DEPTH + SFQ_SLOTS values */ 89 typedef unsigned char sfq_index; 90 91 /* 92 * We dont use pointers to save space. 93 * Small indexes [0 ... SFQ_SLOTS - 1] are 'pointers' to slots[] array 94 * while following values [SFQ_SLOTS ... SFQ_SLOTS + SFQ_DEPTH - 1] 95 * are 'pointers' to dep[] array 96 */ 97 struct sfq_head { 98 sfq_index next; 99 sfq_index prev; 100 }; 101 102 struct sfq_slot { 103 struct sk_buff *skblist_next; 104 struct sk_buff *skblist_prev; 105 sfq_index qlen; /* number of skbs in skblist */ 106 sfq_index next; /* next slot in sfq chain */ 107 struct sfq_head dep; /* anchor in dep[] chains */ 108 unsigned short hash; /* hash value (index in ht[]) */ 109 short allot; /* credit for this slot */ 110 }; 111 112 struct sfq_sched_data { 113 /* Parameters */ 114 int perturb_period; 115 unsigned int quantum; /* Allotment per round: MUST BE >= MTU */ 116 int limit; 117 unsigned int divisor; /* number of slots in hash table */ 118 /* Variables */ 119 struct tcf_proto *filter_list; 120 struct timer_list perturb_timer; 121 u32 perturbation; 122 sfq_index cur_depth; /* depth of longest slot */ 123 unsigned short scaled_quantum; /* SFQ_ALLOT_SIZE(quantum) */ 124 struct sfq_slot *tail; /* current slot in round */ 125 sfq_index *ht; /* Hash table (divisor slots) */ 126 struct sfq_slot slots[SFQ_SLOTS]; 127 struct sfq_head dep[SFQ_DEPTH]; /* Linked list of slots, indexed by depth */ 128 }; 129 130 /* 131 * sfq_head are either in a sfq_slot or in dep[] array 132 */ 133 static inline struct sfq_head *sfq_dep_head(struct sfq_sched_data *q, sfq_index val) 134 { 135 if (val < SFQ_SLOTS) 136 return &q->slots[val].dep; 137 return &q->dep[val - SFQ_SLOTS]; 138 } 139 140 static unsigned int sfq_fold_hash(struct sfq_sched_data *q, u32 h, u32 h1) 141 { 142 return jhash_2words(h, h1, q->perturbation) & (q->divisor - 1); 143 } 144 145 static unsigned int sfq_hash(struct sfq_sched_data *q, struct sk_buff *skb) 146 { 147 u32 h, h2; 148 149 switch (skb->protocol) { 150 case htons(ETH_P_IP): 151 { 152 const struct iphdr *iph; 153 int poff; 154 155 if (!pskb_network_may_pull(skb, sizeof(*iph))) 156 goto err; 157 iph = ip_hdr(skb); 158 h = (__force u32)iph->daddr; 159 h2 = (__force u32)iph->saddr ^ iph->protocol; 160 if (ip_is_fragment(iph)) 161 break; 162 poff = proto_ports_offset(iph->protocol); 163 if (poff >= 0 && 164 pskb_network_may_pull(skb, iph->ihl * 4 + 4 + poff)) { 165 iph = ip_hdr(skb); 166 h2 ^= *(u32 *)((void *)iph + iph->ihl * 4 + poff); 167 } 168 break; 169 } 170 case htons(ETH_P_IPV6): 171 { 172 const struct ipv6hdr *iph; 173 int poff; 174 175 if (!pskb_network_may_pull(skb, sizeof(*iph))) 176 goto err; 177 iph = ipv6_hdr(skb); 178 h = (__force u32)iph->daddr.s6_addr32[3]; 179 h2 = (__force u32)iph->saddr.s6_addr32[3] ^ iph->nexthdr; 180 poff = proto_ports_offset(iph->nexthdr); 181 if (poff >= 0 && 182 pskb_network_may_pull(skb, sizeof(*iph) + 4 + poff)) { 183 iph = ipv6_hdr(skb); 184 h2 ^= *(u32 *)((void *)iph + sizeof(*iph) + poff); 185 } 186 break; 187 } 188 default: 189 err: 190 h = (unsigned long)skb_dst(skb) ^ (__force u32)skb->protocol; 191 h2 = (unsigned long)skb->sk; 192 } 193 194 return sfq_fold_hash(q, h, h2); 195 } 196 197 static unsigned int sfq_classify(struct sk_buff *skb, struct Qdisc *sch, 198 int *qerr) 199 { 200 struct sfq_sched_data *q = qdisc_priv(sch); 201 struct tcf_result res; 202 int result; 203 204 if (TC_H_MAJ(skb->priority) == sch->handle && 205 TC_H_MIN(skb->priority) > 0 && 206 TC_H_MIN(skb->priority) <= q->divisor) 207 return TC_H_MIN(skb->priority); 208 209 if (!q->filter_list) 210 return sfq_hash(q, skb) + 1; 211 212 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; 213 result = tc_classify(skb, q->filter_list, &res); 214 if (result >= 0) { 215 #ifdef CONFIG_NET_CLS_ACT 216 switch (result) { 217 case TC_ACT_STOLEN: 218 case TC_ACT_QUEUED: 219 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN; 220 case TC_ACT_SHOT: 221 return 0; 222 } 223 #endif 224 if (TC_H_MIN(res.classid) <= q->divisor) 225 return TC_H_MIN(res.classid); 226 } 227 return 0; 228 } 229 230 /* 231 * x : slot number [0 .. SFQ_SLOTS - 1] 232 */ 233 static inline void sfq_link(struct sfq_sched_data *q, sfq_index x) 234 { 235 sfq_index p, n; 236 int qlen = q->slots[x].qlen; 237 238 p = qlen + SFQ_SLOTS; 239 n = q->dep[qlen].next; 240 241 q->slots[x].dep.next = n; 242 q->slots[x].dep.prev = p; 243 244 q->dep[qlen].next = x; /* sfq_dep_head(q, p)->next = x */ 245 sfq_dep_head(q, n)->prev = x; 246 } 247 248 #define sfq_unlink(q, x, n, p) \ 249 n = q->slots[x].dep.next; \ 250 p = q->slots[x].dep.prev; \ 251 sfq_dep_head(q, p)->next = n; \ 252 sfq_dep_head(q, n)->prev = p 253 254 255 static inline void sfq_dec(struct sfq_sched_data *q, sfq_index x) 256 { 257 sfq_index p, n; 258 int d; 259 260 sfq_unlink(q, x, n, p); 261 262 d = q->slots[x].qlen--; 263 if (n == p && q->cur_depth == d) 264 q->cur_depth--; 265 sfq_link(q, x); 266 } 267 268 static inline void sfq_inc(struct sfq_sched_data *q, sfq_index x) 269 { 270 sfq_index p, n; 271 int d; 272 273 sfq_unlink(q, x, n, p); 274 275 d = ++q->slots[x].qlen; 276 if (q->cur_depth < d) 277 q->cur_depth = d; 278 sfq_link(q, x); 279 } 280 281 /* helper functions : might be changed when/if skb use a standard list_head */ 282 283 /* remove one skb from tail of slot queue */ 284 static inline struct sk_buff *slot_dequeue_tail(struct sfq_slot *slot) 285 { 286 struct sk_buff *skb = slot->skblist_prev; 287 288 slot->skblist_prev = skb->prev; 289 skb->prev->next = (struct sk_buff *)slot; 290 skb->next = skb->prev = NULL; 291 return skb; 292 } 293 294 /* remove one skb from head of slot queue */ 295 static inline struct sk_buff *slot_dequeue_head(struct sfq_slot *slot) 296 { 297 struct sk_buff *skb = slot->skblist_next; 298 299 slot->skblist_next = skb->next; 300 skb->next->prev = (struct sk_buff *)slot; 301 skb->next = skb->prev = NULL; 302 return skb; 303 } 304 305 static inline void slot_queue_init(struct sfq_slot *slot) 306 { 307 slot->skblist_prev = slot->skblist_next = (struct sk_buff *)slot; 308 } 309 310 /* add skb to slot queue (tail add) */ 311 static inline void slot_queue_add(struct sfq_slot *slot, struct sk_buff *skb) 312 { 313 skb->prev = slot->skblist_prev; 314 skb->next = (struct sk_buff *)slot; 315 slot->skblist_prev->next = skb; 316 slot->skblist_prev = skb; 317 } 318 319 #define slot_queue_walk(slot, skb) \ 320 for (skb = slot->skblist_next; \ 321 skb != (struct sk_buff *)slot; \ 322 skb = skb->next) 323 324 static unsigned int sfq_drop(struct Qdisc *sch) 325 { 326 struct sfq_sched_data *q = qdisc_priv(sch); 327 sfq_index x, d = q->cur_depth; 328 struct sk_buff *skb; 329 unsigned int len; 330 struct sfq_slot *slot; 331 332 /* Queue is full! Find the longest slot and drop tail packet from it */ 333 if (d > 1) { 334 x = q->dep[d].next; 335 slot = &q->slots[x]; 336 drop: 337 skb = slot_dequeue_tail(slot); 338 len = qdisc_pkt_len(skb); 339 sfq_dec(q, x); 340 kfree_skb(skb); 341 sch->q.qlen--; 342 sch->qstats.drops++; 343 sch->qstats.backlog -= len; 344 return len; 345 } 346 347 if (d == 1) { 348 /* It is difficult to believe, but ALL THE SLOTS HAVE LENGTH 1. */ 349 x = q->tail->next; 350 slot = &q->slots[x]; 351 q->tail->next = slot->next; 352 q->ht[slot->hash] = SFQ_EMPTY_SLOT; 353 goto drop; 354 } 355 356 return 0; 357 } 358 359 static int 360 sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch) 361 { 362 struct sfq_sched_data *q = qdisc_priv(sch); 363 unsigned int hash; 364 sfq_index x, qlen; 365 struct sfq_slot *slot; 366 int uninitialized_var(ret); 367 368 hash = sfq_classify(skb, sch, &ret); 369 if (hash == 0) { 370 if (ret & __NET_XMIT_BYPASS) 371 sch->qstats.drops++; 372 kfree_skb(skb); 373 return ret; 374 } 375 hash--; 376 377 x = q->ht[hash]; 378 slot = &q->slots[x]; 379 if (x == SFQ_EMPTY_SLOT) { 380 x = q->dep[0].next; /* get a free slot */ 381 q->ht[hash] = x; 382 slot = &q->slots[x]; 383 slot->hash = hash; 384 } 385 386 /* If selected queue has length q->limit, do simple tail drop, 387 * i.e. drop _this_ packet. 388 */ 389 if (slot->qlen >= q->limit) 390 return qdisc_drop(skb, sch); 391 392 sch->qstats.backlog += qdisc_pkt_len(skb); 393 slot_queue_add(slot, skb); 394 sfq_inc(q, x); 395 if (slot->qlen == 1) { /* The flow is new */ 396 if (q->tail == NULL) { /* It is the first flow */ 397 slot->next = x; 398 } else { 399 slot->next = q->tail->next; 400 q->tail->next = x; 401 } 402 q->tail = slot; 403 slot->allot = q->scaled_quantum; 404 } 405 if (++sch->q.qlen <= q->limit) 406 return NET_XMIT_SUCCESS; 407 408 qlen = slot->qlen; 409 sfq_drop(sch); 410 /* Return Congestion Notification only if we dropped a packet 411 * from this flow. 412 */ 413 if (qlen != slot->qlen) 414 return NET_XMIT_CN; 415 416 /* As we dropped a packet, better let upper stack know this */ 417 qdisc_tree_decrease_qlen(sch, 1); 418 return NET_XMIT_SUCCESS; 419 } 420 421 static struct sk_buff * 422 sfq_dequeue(struct Qdisc *sch) 423 { 424 struct sfq_sched_data *q = qdisc_priv(sch); 425 struct sk_buff *skb; 426 sfq_index a, next_a; 427 struct sfq_slot *slot; 428 429 /* No active slots */ 430 if (q->tail == NULL) 431 return NULL; 432 433 next_slot: 434 a = q->tail->next; 435 slot = &q->slots[a]; 436 if (slot->allot <= 0) { 437 q->tail = slot; 438 slot->allot += q->scaled_quantum; 439 goto next_slot; 440 } 441 skb = slot_dequeue_head(slot); 442 sfq_dec(q, a); 443 qdisc_bstats_update(sch, skb); 444 sch->q.qlen--; 445 sch->qstats.backlog -= qdisc_pkt_len(skb); 446 447 /* Is the slot empty? */ 448 if (slot->qlen == 0) { 449 q->ht[slot->hash] = SFQ_EMPTY_SLOT; 450 next_a = slot->next; 451 if (a == next_a) { 452 q->tail = NULL; /* no more active slots */ 453 return skb; 454 } 455 q->tail->next = next_a; 456 } else { 457 slot->allot -= SFQ_ALLOT_SIZE(qdisc_pkt_len(skb)); 458 } 459 return skb; 460 } 461 462 static void 463 sfq_reset(struct Qdisc *sch) 464 { 465 struct sk_buff *skb; 466 467 while ((skb = sfq_dequeue(sch)) != NULL) 468 kfree_skb(skb); 469 } 470 471 static void sfq_perturbation(unsigned long arg) 472 { 473 struct Qdisc *sch = (struct Qdisc *)arg; 474 struct sfq_sched_data *q = qdisc_priv(sch); 475 476 q->perturbation = net_random(); 477 478 if (q->perturb_period) 479 mod_timer(&q->perturb_timer, jiffies + q->perturb_period); 480 } 481 482 static int sfq_change(struct Qdisc *sch, struct nlattr *opt) 483 { 484 struct sfq_sched_data *q = qdisc_priv(sch); 485 struct tc_sfq_qopt *ctl = nla_data(opt); 486 unsigned int qlen; 487 488 if (opt->nla_len < nla_attr_size(sizeof(*ctl))) 489 return -EINVAL; 490 491 if (ctl->divisor && 492 (!is_power_of_2(ctl->divisor) || ctl->divisor > 65536)) 493 return -EINVAL; 494 495 sch_tree_lock(sch); 496 q->quantum = ctl->quantum ? : psched_mtu(qdisc_dev(sch)); 497 q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum); 498 q->perturb_period = ctl->perturb_period * HZ; 499 if (ctl->limit) 500 q->limit = min_t(u32, ctl->limit, SFQ_DEPTH - 1); 501 if (ctl->divisor) 502 q->divisor = ctl->divisor; 503 qlen = sch->q.qlen; 504 while (sch->q.qlen > q->limit) 505 sfq_drop(sch); 506 qdisc_tree_decrease_qlen(sch, qlen - sch->q.qlen); 507 508 del_timer(&q->perturb_timer); 509 if (q->perturb_period) { 510 mod_timer(&q->perturb_timer, jiffies + q->perturb_period); 511 q->perturbation = net_random(); 512 } 513 sch_tree_unlock(sch); 514 return 0; 515 } 516 517 static int sfq_init(struct Qdisc *sch, struct nlattr *opt) 518 { 519 struct sfq_sched_data *q = qdisc_priv(sch); 520 size_t sz; 521 int i; 522 523 q->perturb_timer.function = sfq_perturbation; 524 q->perturb_timer.data = (unsigned long)sch; 525 init_timer_deferrable(&q->perturb_timer); 526 527 for (i = 0; i < SFQ_DEPTH; i++) { 528 q->dep[i].next = i + SFQ_SLOTS; 529 q->dep[i].prev = i + SFQ_SLOTS; 530 } 531 532 q->limit = SFQ_DEPTH - 1; 533 q->cur_depth = 0; 534 q->tail = NULL; 535 q->divisor = SFQ_DEFAULT_HASH_DIVISOR; 536 if (opt == NULL) { 537 q->quantum = psched_mtu(qdisc_dev(sch)); 538 q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum); 539 q->perturb_period = 0; 540 q->perturbation = net_random(); 541 } else { 542 int err = sfq_change(sch, opt); 543 if (err) 544 return err; 545 } 546 547 sz = sizeof(q->ht[0]) * q->divisor; 548 q->ht = kmalloc(sz, GFP_KERNEL); 549 if (!q->ht && sz > PAGE_SIZE) 550 q->ht = vmalloc(sz); 551 if (!q->ht) 552 return -ENOMEM; 553 for (i = 0; i < q->divisor; i++) 554 q->ht[i] = SFQ_EMPTY_SLOT; 555 556 for (i = 0; i < SFQ_SLOTS; i++) { 557 slot_queue_init(&q->slots[i]); 558 sfq_link(q, i); 559 } 560 if (q->limit >= 1) 561 sch->flags |= TCQ_F_CAN_BYPASS; 562 else 563 sch->flags &= ~TCQ_F_CAN_BYPASS; 564 return 0; 565 } 566 567 static void sfq_destroy(struct Qdisc *sch) 568 { 569 struct sfq_sched_data *q = qdisc_priv(sch); 570 571 tcf_destroy_chain(&q->filter_list); 572 q->perturb_period = 0; 573 del_timer_sync(&q->perturb_timer); 574 if (is_vmalloc_addr(q->ht)) 575 vfree(q->ht); 576 else 577 kfree(q->ht); 578 } 579 580 static int sfq_dump(struct Qdisc *sch, struct sk_buff *skb) 581 { 582 struct sfq_sched_data *q = qdisc_priv(sch); 583 unsigned char *b = skb_tail_pointer(skb); 584 struct tc_sfq_qopt opt; 585 586 opt.quantum = q->quantum; 587 opt.perturb_period = q->perturb_period / HZ; 588 589 opt.limit = q->limit; 590 opt.divisor = q->divisor; 591 opt.flows = q->limit; 592 593 NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt); 594 595 return skb->len; 596 597 nla_put_failure: 598 nlmsg_trim(skb, b); 599 return -1; 600 } 601 602 static struct Qdisc *sfq_leaf(struct Qdisc *sch, unsigned long arg) 603 { 604 return NULL; 605 } 606 607 static unsigned long sfq_get(struct Qdisc *sch, u32 classid) 608 { 609 return 0; 610 } 611 612 static unsigned long sfq_bind(struct Qdisc *sch, unsigned long parent, 613 u32 classid) 614 { 615 /* we cannot bypass queue discipline anymore */ 616 sch->flags &= ~TCQ_F_CAN_BYPASS; 617 return 0; 618 } 619 620 static void sfq_put(struct Qdisc *q, unsigned long cl) 621 { 622 } 623 624 static struct tcf_proto **sfq_find_tcf(struct Qdisc *sch, unsigned long cl) 625 { 626 struct sfq_sched_data *q = qdisc_priv(sch); 627 628 if (cl) 629 return NULL; 630 return &q->filter_list; 631 } 632 633 static int sfq_dump_class(struct Qdisc *sch, unsigned long cl, 634 struct sk_buff *skb, struct tcmsg *tcm) 635 { 636 tcm->tcm_handle |= TC_H_MIN(cl); 637 return 0; 638 } 639 640 static int sfq_dump_class_stats(struct Qdisc *sch, unsigned long cl, 641 struct gnet_dump *d) 642 { 643 struct sfq_sched_data *q = qdisc_priv(sch); 644 sfq_index idx = q->ht[cl - 1]; 645 struct gnet_stats_queue qs = { 0 }; 646 struct tc_sfq_xstats xstats = { 0 }; 647 struct sk_buff *skb; 648 649 if (idx != SFQ_EMPTY_SLOT) { 650 const struct sfq_slot *slot = &q->slots[idx]; 651 652 xstats.allot = slot->allot << SFQ_ALLOT_SHIFT; 653 qs.qlen = slot->qlen; 654 slot_queue_walk(slot, skb) 655 qs.backlog += qdisc_pkt_len(skb); 656 } 657 if (gnet_stats_copy_queue(d, &qs) < 0) 658 return -1; 659 return gnet_stats_copy_app(d, &xstats, sizeof(xstats)); 660 } 661 662 static void sfq_walk(struct Qdisc *sch, struct qdisc_walker *arg) 663 { 664 struct sfq_sched_data *q = qdisc_priv(sch); 665 unsigned int i; 666 667 if (arg->stop) 668 return; 669 670 for (i = 0; i < q->divisor; i++) { 671 if (q->ht[i] == SFQ_EMPTY_SLOT || 672 arg->count < arg->skip) { 673 arg->count++; 674 continue; 675 } 676 if (arg->fn(sch, i + 1, arg) < 0) { 677 arg->stop = 1; 678 break; 679 } 680 arg->count++; 681 } 682 } 683 684 static const struct Qdisc_class_ops sfq_class_ops = { 685 .leaf = sfq_leaf, 686 .get = sfq_get, 687 .put = sfq_put, 688 .tcf_chain = sfq_find_tcf, 689 .bind_tcf = sfq_bind, 690 .unbind_tcf = sfq_put, 691 .dump = sfq_dump_class, 692 .dump_stats = sfq_dump_class_stats, 693 .walk = sfq_walk, 694 }; 695 696 static struct Qdisc_ops sfq_qdisc_ops __read_mostly = { 697 .cl_ops = &sfq_class_ops, 698 .id = "sfq", 699 .priv_size = sizeof(struct sfq_sched_data), 700 .enqueue = sfq_enqueue, 701 .dequeue = sfq_dequeue, 702 .peek = qdisc_peek_dequeued, 703 .drop = sfq_drop, 704 .init = sfq_init, 705 .reset = sfq_reset, 706 .destroy = sfq_destroy, 707 .change = NULL, 708 .dump = sfq_dump, 709 .owner = THIS_MODULE, 710 }; 711 712 static int __init sfq_module_init(void) 713 { 714 return register_qdisc(&sfq_qdisc_ops); 715 } 716 static void __exit sfq_module_exit(void) 717 { 718 unregister_qdisc(&sfq_qdisc_ops); 719 } 720 module_init(sfq_module_init) 721 module_exit(sfq_module_exit) 722 MODULE_LICENSE("GPL"); 723