1// SPDX-License-Identifier: GPL-2.0-or-later 2/* 3 * net/sched/sch_tbf.c Token Bucket Filter queue. 4 * 5 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> 6 * Dmitry Torokhov <dtor@mail.ru> - allow attaching inner qdiscs - 7 * original idea by Martin Devera 8 */ 9 10#include <linux/module.h> 11#include <linux/types.h> 12#include <linux/kernel.h> 13#include <linux/string.h> 14#include <linux/errno.h> 15#include <linux/skbuff.h> 16#include <net/netlink.h> 17#include <net/sch_generic.h> 18#include <net/pkt_cls.h> 19#include <net/pkt_sched.h> 20 21 22/* Simple Token Bucket Filter. 23 ======================================= 24 25 SOURCE. 26 ------- 27 28 None. 29 30 Description. 31 ------------ 32 33 A data flow obeys TBF with rate R and depth B, if for any 34 time interval t_i...t_f the number of transmitted bits 35 does not exceed B + R*(t_f-t_i). 36 37 Packetized version of this definition: 38 The sequence of packets of sizes s_i served at moments t_i 39 obeys TBF, if for any i<=k: 40 41 s_i+....+s_k <= B + R*(t_k - t_i) 42 43 Algorithm. 44 ---------- 45 46 Let N(t_i) be B/R initially and N(t) grow continuously with time as: 47 48 N(t+delta) = min{B/R, N(t) + delta} 49 50 If the first packet in queue has length S, it may be 51 transmitted only at the time t_* when S/R <= N(t_*), 52 and in this case N(t) jumps: 53 54 N(t_* + 0) = N(t_* - 0) - S/R. 55 56 57 58 Actually, QoS requires two TBF to be applied to a data stream. 59 One of them controls steady state burst size, another 60 one with rate P (peak rate) and depth M (equal to link MTU) 61 limits bursts at a smaller time scale. 62 63 It is easy to see that P>R, and B>M. If P is infinity, this double 64 TBF is equivalent to a single one. 65 66 When TBF works in reshaping mode, latency is estimated as: 67 68 lat = max ((L-B)/R, (L-M)/P) 69 70 71 NOTES. 72 ------ 73 74 If TBF throttles, it starts a watchdog timer, which will wake it up 75 when it is ready to transmit. 76 Note that the minimal timer resolution is 1/HZ. 77 If no new packets arrive during this period, 78 or if the device is not awaken by EOI for some previous packet, 79 TBF can stop its activity for 1/HZ. 80 81 82 This means, that with depth B, the maximal rate is 83 84 R_crit = B*HZ 85 86 F.e. for 10Mbit ethernet and HZ=100 the minimal allowed B is ~10Kbytes. 87 88 Note that the peak rate TBF is much more tough: with MTU 1500 89 P_crit = 150Kbytes/sec. So, if you need greater peak 90 rates, use alpha with HZ=1000 :-) 91 92 With classful TBF, limit is just kept for backwards compatibility. 93 It is passed to the default bfifo qdisc - if the inner qdisc is 94 changed the limit is not effective anymore. 95*/ 96 97struct tbf_sched_data { 98/* Parameters */ 99 u32 limit; /* Maximal length of backlog: bytes */ 100 u32 max_size; 101 s64 buffer; /* Token bucket depth/rate: MUST BE >= MTU/B */ 102 s64 mtu; 103 struct psched_ratecfg rate; 104 struct psched_ratecfg peak; 105 106/* Variables */ 107 s64 tokens; /* Current number of B tokens */ 108 s64 ptokens; /* Current number of P tokens */ 109 s64 t_c; /* Time check-point */ 110 struct Qdisc *qdisc; /* Inner qdisc, default - bfifo queue */ 111 struct qdisc_watchdog watchdog; /* Watchdog timer */ 112}; 113 114 115/* Time to Length, convert time in ns to length in bytes 116 * to determinate how many bytes can be sent in given time. 117 */ 118static u64 psched_ns_t2l(const struct psched_ratecfg *r, 119 u64 time_in_ns) 120{ 121 /* The formula is : 122 * len = (time_in_ns * r->rate_bytes_ps) / NSEC_PER_SEC 123 */ 124 u64 len = time_in_ns * r->rate_bytes_ps; 125 126 do_div(len, NSEC_PER_SEC); 127 128 if (unlikely(r->linklayer == TC_LINKLAYER_ATM)) { 129 do_div(len, 53); 130 len = len * 48; 131 } 132 133 if (len > r->overhead) 134 len -= r->overhead; 135 else 136 len = 0; 137 138 return len; 139} 140 141static void tbf_offload_change(struct Qdisc *sch) 142{ 143 struct tbf_sched_data *q = qdisc_priv(sch); 144 struct net_device *dev = qdisc_dev(sch); 145 struct tc_tbf_qopt_offload qopt; 146 147 if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc) 148 return; 149 150 qopt.command = TC_TBF_REPLACE; 151 qopt.handle = sch->handle; 152 qopt.parent = sch->parent; 153 qopt.replace_params.rate = q->rate; 154 qopt.replace_params.max_size = q->max_size; 155 qopt.replace_params.qstats = &sch->qstats; 156 157 dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_TBF, &qopt); 158} 159 160static void tbf_offload_destroy(struct Qdisc *sch) 161{ 162 struct net_device *dev = qdisc_dev(sch); 163 struct tc_tbf_qopt_offload qopt; 164 165 if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc) 166 return; 167 168 qopt.command = TC_TBF_DESTROY; 169 qopt.handle = sch->handle; 170 qopt.parent = sch->parent; 171 dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_TBF, &qopt); 172} 173 174static int tbf_offload_dump(struct Qdisc *sch) 175{ 176 struct tc_tbf_qopt_offload qopt; 177 178 qopt.command = TC_TBF_STATS; 179 qopt.handle = sch->handle; 180 qopt.parent = sch->parent; 181 qopt.stats.bstats = &sch->bstats; 182 qopt.stats.qstats = &sch->qstats; 183 184 return qdisc_offload_dump_helper(sch, TC_SETUP_QDISC_TBF, &qopt); 185} 186 187/* GSO packet is too big, segment it so that tbf can transmit 188 * each segment in time 189 */ 190static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch, 191 struct sk_buff **to_free) 192{ 193 struct tbf_sched_data *q = qdisc_priv(sch); 194 struct sk_buff *segs, *nskb; 195 netdev_features_t features = netif_skb_features(skb); 196 unsigned int len = 0, prev_len = qdisc_pkt_len(skb); 197 int ret, nb; 198 199 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK); 200 201 if (IS_ERR_OR_NULL(segs)) 202 return qdisc_drop(skb, sch, to_free); 203 204 nb = 0; 205 skb_list_walk_safe(segs, segs, nskb) { 206 skb_mark_not_on_list(segs); 207 qdisc_skb_cb(segs)->pkt_len = segs->len; 208 len += segs->len; 209 ret = qdisc_enqueue(segs, q->qdisc, to_free); 210 if (ret != NET_XMIT_SUCCESS) { 211 if (net_xmit_drop_count(ret)) 212 qdisc_qstats_drop(sch); 213 } else { 214 nb++; 215 } 216 } 217 sch->q.qlen += nb; 218 if (nb > 1) 219 qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len); 220 consume_skb(skb); 221 return nb > 0 ? NET_XMIT_SUCCESS : NET_XMIT_DROP; 222} 223 224static int tbf_enqueue(struct sk_buff *skb, struct Qdisc *sch, 225 struct sk_buff **to_free) 226{ 227 struct tbf_sched_data *q = qdisc_priv(sch); 228 unsigned int len = qdisc_pkt_len(skb); 229 int ret; 230 231 if (qdisc_pkt_len(skb) > q->max_size) { 232 if (skb_is_gso(skb) && 233 skb_gso_validate_mac_len(skb, q->max_size)) 234 return tbf_segment(skb, sch, to_free); 235 return qdisc_drop(skb, sch, to_free); 236 } 237 ret = qdisc_enqueue(skb, q->qdisc, to_free); 238 if (ret != NET_XMIT_SUCCESS) { 239 if (net_xmit_drop_count(ret)) 240 qdisc_qstats_drop(sch); 241 return ret; 242 } 243 244 sch->qstats.backlog += len; 245 sch->q.qlen++; 246 return NET_XMIT_SUCCESS; 247} 248 249static bool tbf_peak_present(const struct tbf_sched_data *q) 250{ 251 return q->peak.rate_bytes_ps; 252} 253 254static struct sk_buff *tbf_dequeue(struct Qdisc *sch) 255{ 256 struct tbf_sched_data *q = qdisc_priv(sch); 257 struct sk_buff *skb; 258 259 skb = q->qdisc->ops->peek(q->qdisc); 260 261 if (skb) { 262 s64 now; 263 s64 toks; 264 s64 ptoks = 0; 265 unsigned int len = qdisc_pkt_len(skb); 266 267 now = ktime_get_ns(); 268 toks = min_t(s64, now - q->t_c, q->buffer); 269 270 if (tbf_peak_present(q)) { 271 ptoks = toks + q->ptokens; 272 if (ptoks > q->mtu) 273 ptoks = q->mtu; 274 ptoks -= (s64) psched_l2t_ns(&q->peak, len); 275 } 276 toks += q->tokens; 277 if (toks > q->buffer) 278 toks = q->buffer; 279 toks -= (s64) psched_l2t_ns(&q->rate, len); 280 281 if ((toks|ptoks) >= 0) { 282 skb = qdisc_dequeue_peeked(q->qdisc); 283 if (unlikely(!skb)) 284 return NULL; 285 286 q->t_c = now; 287 q->tokens = toks; 288 q->ptokens = ptoks; 289 qdisc_qstats_backlog_dec(sch, skb); 290 sch->q.qlen--; 291 qdisc_bstats_update(sch, skb); 292 return skb; 293 } 294 295 qdisc_watchdog_schedule_ns(&q->watchdog, 296 now + max_t(long, -toks, -ptoks)); 297 298 /* Maybe we have a shorter packet in the queue, 299 which can be sent now. It sounds cool, 300 but, however, this is wrong in principle. 301 We MUST NOT reorder packets under these circumstances. 302 303 Really, if we split the flow into independent 304 subflows, it would be a very good solution. 305 This is the main idea of all FQ algorithms 306 (cf. CSZ, HPFQ, HFSC) 307 */ 308 309 qdisc_qstats_overlimit(sch); 310 } 311 return NULL; 312} 313 314static void tbf_reset(struct Qdisc *sch) 315{ 316 struct tbf_sched_data *q = qdisc_priv(sch); 317 318 qdisc_reset(q->qdisc); 319 q->t_c = ktime_get_ns(); 320 q->tokens = q->buffer; 321 q->ptokens = q->mtu; 322 qdisc_watchdog_cancel(&q->watchdog); 323} 324 325static const struct nla_policy tbf_policy[TCA_TBF_MAX + 1] = { 326 [TCA_TBF_PARMS] = { .len = sizeof(struct tc_tbf_qopt) }, 327 [TCA_TBF_RTAB] = { .type = NLA_BINARY, .len = TC_RTAB_SIZE }, 328 [TCA_TBF_PTAB] = { .type = NLA_BINARY, .len = TC_RTAB_SIZE }, 329 [TCA_TBF_RATE64] = { .type = NLA_U64 }, 330 [TCA_TBF_PRATE64] = { .type = NLA_U64 }, 331 [TCA_TBF_BURST] = { .type = NLA_U32 }, 332 [TCA_TBF_PBURST] = { .type = NLA_U32 }, 333}; 334 335static int tbf_change(struct Qdisc *sch, struct nlattr *opt, 336 struct netlink_ext_ack *extack) 337{ 338 int err; 339 struct tbf_sched_data *q = qdisc_priv(sch); 340 struct nlattr *tb[TCA_TBF_MAX + 1]; 341 struct tc_tbf_qopt *qopt; 342 struct Qdisc *child = NULL; 343 struct Qdisc *old = NULL; 344 struct psched_ratecfg rate; 345 struct psched_ratecfg peak; 346 u64 max_size; 347 s64 buffer, mtu; 348 u64 rate64 = 0, prate64 = 0; 349 350 err = nla_parse_nested_deprecated(tb, TCA_TBF_MAX, opt, tbf_policy, 351 NULL); 352 if (err < 0) 353 return err; 354 355 err = -EINVAL; 356 if (tb[TCA_TBF_PARMS] == NULL) 357 goto done; 358 359 qopt = nla_data(tb[TCA_TBF_PARMS]); 360 if (qopt->rate.linklayer == TC_LINKLAYER_UNAWARE) 361 qdisc_put_rtab(qdisc_get_rtab(&qopt->rate, 362 tb[TCA_TBF_RTAB], 363 NULL)); 364 365 if (qopt->peakrate.linklayer == TC_LINKLAYER_UNAWARE) 366 qdisc_put_rtab(qdisc_get_rtab(&qopt->peakrate, 367 tb[TCA_TBF_PTAB], 368 NULL)); 369 370 buffer = min_t(u64, PSCHED_TICKS2NS(qopt->buffer), ~0U); 371 mtu = min_t(u64, PSCHED_TICKS2NS(qopt->mtu), ~0U); 372 373 if (tb[TCA_TBF_RATE64]) 374 rate64 = nla_get_u64(tb[TCA_TBF_RATE64]); 375 psched_ratecfg_precompute(&rate, &qopt->rate, rate64); 376 377 if (tb[TCA_TBF_BURST]) { 378 max_size = nla_get_u32(tb[TCA_TBF_BURST]); 379 buffer = psched_l2t_ns(&rate, max_size); 380 } else { 381 max_size = min_t(u64, psched_ns_t2l(&rate, buffer), ~0U); 382 } 383 384 if (qopt->peakrate.rate) { 385 if (tb[TCA_TBF_PRATE64]) 386 prate64 = nla_get_u64(tb[TCA_TBF_PRATE64]); 387 psched_ratecfg_precompute(&peak, &qopt->peakrate, prate64); 388 if (peak.rate_bytes_ps <= rate.rate_bytes_ps) { 389 pr_warn_ratelimited("sch_tbf: peakrate %llu is lower than or equals to rate %llu !\n", 390 peak.rate_bytes_ps, rate.rate_bytes_ps); 391 err = -EINVAL; 392 goto done; 393 } 394 395 if (tb[TCA_TBF_PBURST]) { 396 u32 pburst = nla_get_u32(tb[TCA_TBF_PBURST]); 397 max_size = min_t(u32, max_size, pburst); 398 mtu = psched_l2t_ns(&peak, pburst); 399 } else { 400 max_size = min_t(u64, max_size, psched_ns_t2l(&peak, mtu)); 401 } 402 } else { 403 memset(&peak, 0, sizeof(peak)); 404 } 405 406 if (max_size < psched_mtu(qdisc_dev(sch))) 407 pr_warn_ratelimited("sch_tbf: burst %llu is lower than device %s mtu (%u) !\n", 408 max_size, qdisc_dev(sch)->name, 409 psched_mtu(qdisc_dev(sch))); 410 411 if (!max_size) { 412 err = -EINVAL; 413 goto done; 414 } 415 416 if (q->qdisc != &noop_qdisc) { 417 err = fifo_set_limit(q->qdisc, qopt->limit); 418 if (err) 419 goto done; 420 } else if (qopt->limit > 0) { 421 child = fifo_create_dflt(sch, &bfifo_qdisc_ops, qopt->limit, 422 extack); 423 if (IS_ERR(child)) { 424 err = PTR_ERR(child); 425 goto done; 426 } 427 428 /* child is fifo, no need to check for noop_qdisc */ 429 qdisc_hash_add(child, true); 430 } 431 432 sch_tree_lock(sch); 433 if (child) { 434 qdisc_tree_flush_backlog(q->qdisc); 435 old = q->qdisc; 436 q->qdisc = child; 437 } 438 q->limit = qopt->limit; 439 if (tb[TCA_TBF_PBURST]) 440 q->mtu = mtu; 441 else 442 q->mtu = PSCHED_TICKS2NS(qopt->mtu); 443 q->max_size = max_size; 444 if (tb[TCA_TBF_BURST]) 445 q->buffer = buffer; 446 else 447 q->buffer = PSCHED_TICKS2NS(qopt->buffer); 448 q->tokens = q->buffer; 449 q->ptokens = q->mtu; 450 451 memcpy(&q->rate, &rate, sizeof(struct psched_ratecfg)); 452 memcpy(&q->peak, &peak, sizeof(struct psched_ratecfg)); 453 454 sch_tree_unlock(sch); 455 qdisc_put(old); 456 err = 0; 457 458 tbf_offload_change(sch); 459done: 460 return err; 461} 462 463static int tbf_init(struct Qdisc *sch, struct nlattr *opt, 464 struct netlink_ext_ack *extack) 465{ 466 struct tbf_sched_data *q = qdisc_priv(sch); 467 468 qdisc_watchdog_init(&q->watchdog, sch); 469 q->qdisc = &noop_qdisc; 470 471 if (!opt) 472 return -EINVAL; 473 474 q->t_c = ktime_get_ns(); 475 476 return tbf_change(sch, opt, extack); 477} 478 479static void tbf_destroy(struct Qdisc *sch) 480{ 481 struct tbf_sched_data *q = qdisc_priv(sch); 482 483 qdisc_watchdog_cancel(&q->watchdog); 484 tbf_offload_destroy(sch); 485 qdisc_put(q->qdisc); 486} 487 488static int tbf_dump(struct Qdisc *sch, struct sk_buff *skb) 489{ 490 struct tbf_sched_data *q = qdisc_priv(sch); 491 struct nlattr *nest; 492 struct tc_tbf_qopt opt; 493 int err; 494 495 err = tbf_offload_dump(sch); 496 if (err) 497 return err; 498 499 nest = nla_nest_start_noflag(skb, TCA_OPTIONS); 500 if (nest == NULL) 501 goto nla_put_failure; 502 503 opt.limit = q->limit; 504 psched_ratecfg_getrate(&opt.rate, &q->rate); 505 if (tbf_peak_present(q)) 506 psched_ratecfg_getrate(&opt.peakrate, &q->peak); 507 else 508 memset(&opt.peakrate, 0, sizeof(opt.peakrate)); 509 opt.mtu = PSCHED_NS2TICKS(q->mtu); 510 opt.buffer = PSCHED_NS2TICKS(q->buffer); 511 if (nla_put(skb, TCA_TBF_PARMS, sizeof(opt), &opt)) 512 goto nla_put_failure; 513 if (q->rate.rate_bytes_ps >= (1ULL << 32) && 514 nla_put_u64_64bit(skb, TCA_TBF_RATE64, q->rate.rate_bytes_ps, 515 TCA_TBF_PAD)) 516 goto nla_put_failure; 517 if (tbf_peak_present(q) && 518 q->peak.rate_bytes_ps >= (1ULL << 32) && 519 nla_put_u64_64bit(skb, TCA_TBF_PRATE64, q->peak.rate_bytes_ps, 520 TCA_TBF_PAD)) 521 goto nla_put_failure; 522 523 return nla_nest_end(skb, nest); 524 525nla_put_failure: 526 nla_nest_cancel(skb, nest); 527 return -1; 528} 529 530static int tbf_dump_class(struct Qdisc *sch, unsigned long cl, 531 struct sk_buff *skb, struct tcmsg *tcm) 532{ 533 struct tbf_sched_data *q = qdisc_priv(sch); 534 535 tcm->tcm_handle |= TC_H_MIN(1); 536 tcm->tcm_info = q->qdisc->handle; 537 538 return 0; 539} 540 541static int tbf_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, 542 struct Qdisc **old, struct netlink_ext_ack *extack) 543{ 544 struct tbf_sched_data *q = qdisc_priv(sch); 545 546 if (new == NULL) 547 new = &noop_qdisc; 548 549 *old = qdisc_replace(sch, new, &q->qdisc); 550 return 0; 551} 552 553static struct Qdisc *tbf_leaf(struct Qdisc *sch, unsigned long arg) 554{ 555 struct tbf_sched_data *q = qdisc_priv(sch); 556 return q->qdisc; 557} 558 559static unsigned long tbf_find(struct Qdisc *sch, u32 classid) 560{ 561 return 1; 562} 563 564static void tbf_walk(struct Qdisc *sch, struct qdisc_walker *walker) 565{ 566 if (!walker->stop) { 567 if (walker->count >= walker->skip) 568 if (walker->fn(sch, 1, walker) < 0) { 569 walker->stop = 1; 570 return; 571 } 572 walker->count++; 573 } 574} 575 576static const struct Qdisc_class_ops tbf_class_ops = { 577 .graft = tbf_graft, 578 .leaf = tbf_leaf, 579 .find = tbf_find, 580 .walk = tbf_walk, 581 .dump = tbf_dump_class, 582}; 583 584static struct Qdisc_ops tbf_qdisc_ops __read_mostly = { 585 .next = NULL, 586 .cl_ops = &tbf_class_ops, 587 .id = "tbf", 588 .priv_size = sizeof(struct tbf_sched_data), 589 .enqueue = tbf_enqueue, 590 .dequeue = tbf_dequeue, 591 .peek = qdisc_peek_dequeued, 592 .init = tbf_init, 593 .reset = tbf_reset, 594 .destroy = tbf_destroy, 595 .change = tbf_change, 596 .dump = tbf_dump, 597 .owner = THIS_MODULE, 598}; 599 600static int __init tbf_module_init(void) 601{ 602 return register_qdisc(&tbf_qdisc_ops); 603} 604 605static void __exit tbf_module_exit(void) 606{ 607 unregister_qdisc(&tbf_qdisc_ops); 608} 609module_init(tbf_module_init) 610module_exit(tbf_module_exit) 611MODULE_LICENSE("GPL"); 612