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/gso.h> 17 #include <net/netlink.h> 18 #include <net/sch_generic.h> 19 #include <net/pkt_cls.h> 20 #include <net/pkt_sched.h> 21 22 23 /* Simple Token Bucket Filter. 24 ======================================= 25 26 SOURCE. 27 ------- 28 29 None. 30 31 Description. 32 ------------ 33 34 A data flow obeys TBF with rate R and depth B, if for any 35 time interval t_i...t_f the number of transmitted bits 36 does not exceed B + R*(t_f-t_i). 37 38 Packetized version of this definition: 39 The sequence of packets of sizes s_i served at moments t_i 40 obeys TBF, if for any i<=k: 41 42 s_i+....+s_k <= B + R*(t_k - t_i) 43 44 Algorithm. 45 ---------- 46 47 Let N(t_i) be B/R initially and N(t) grow continuously with time as: 48 49 N(t+delta) = min{B/R, N(t) + delta} 50 51 If the first packet in queue has length S, it may be 52 transmitted only at the time t_* when S/R <= N(t_*), 53 and in this case N(t) jumps: 54 55 N(t_* + 0) = N(t_* - 0) - S/R. 56 57 58 59 Actually, QoS requires two TBF to be applied to a data stream. 60 One of them controls steady state burst size, another 61 one with rate P (peak rate) and depth M (equal to link MTU) 62 limits bursts at a smaller time scale. 63 64 It is easy to see that P>R, and B>M. If P is infinity, this double 65 TBF is equivalent to a single one. 66 67 When TBF works in reshaping mode, latency is estimated as: 68 69 lat = max ((L-B)/R, (L-M)/P) 70 71 72 NOTES. 73 ------ 74 75 If TBF throttles, it starts a watchdog timer, which will wake it up 76 when it is ready to transmit. 77 Note that the minimal timer resolution is 1/HZ. 78 If no new packets arrive during this period, 79 or if the device is not awaken by EOI for some previous packet, 80 TBF can stop its activity for 1/HZ. 81 82 83 This means, that with depth B, the maximal rate is 84 85 R_crit = B*HZ 86 87 F.e. for 10Mbit ethernet and HZ=100 the minimal allowed B is ~10Kbytes. 88 89 Note that the peak rate TBF is much more tough: with MTU 1500 90 P_crit = 150Kbytes/sec. So, if you need greater peak 91 rates, use alpha with HZ=1000 :-) 92 93 With classful TBF, limit is just kept for backwards compatibility. 94 It is passed to the default bfifo qdisc - if the inner qdisc is 95 changed the limit is not effective anymore. 96 */ 97 98 struct tbf_sched_data { 99 /* Parameters */ 100 u32 limit; /* Maximal length of backlog: bytes */ 101 u32 max_size; 102 s64 buffer; /* Token bucket depth/rate: MUST BE >= MTU/B */ 103 s64 mtu; 104 struct psched_ratecfg rate; 105 struct psched_ratecfg peak; 106 107 /* Variables */ 108 s64 tokens; /* Current number of B tokens */ 109 s64 ptokens; /* Current number of P tokens */ 110 s64 t_c; /* Time check-point */ 111 struct Qdisc *qdisc; /* Inner qdisc, default - bfifo queue */ 112 struct qdisc_watchdog watchdog; /* Watchdog timer */ 113 }; 114 115 116 /* Time to Length, convert time in ns to length in bytes 117 * to determinate how many bytes can be sent in given time. 118 */ 119 static u64 psched_ns_t2l(const struct psched_ratecfg *r, 120 u64 time_in_ns) 121 { 122 /* The formula is : 123 * len = (time_in_ns * r->rate_bytes_ps) / NSEC_PER_SEC 124 */ 125 u64 len = time_in_ns * r->rate_bytes_ps; 126 127 do_div(len, NSEC_PER_SEC); 128 129 if (unlikely(r->linklayer == TC_LINKLAYER_ATM)) { 130 do_div(len, 53); 131 len = len * 48; 132 } 133 134 if (len > r->overhead) 135 len -= r->overhead; 136 else 137 len = 0; 138 139 return len; 140 } 141 142 static void tbf_offload_change(struct Qdisc *sch) 143 { 144 struct tbf_sched_data *q = qdisc_priv(sch); 145 struct net_device *dev = qdisc_dev(sch); 146 struct tc_tbf_qopt_offload qopt; 147 148 if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc) 149 return; 150 151 qopt.command = TC_TBF_REPLACE; 152 qopt.handle = sch->handle; 153 qopt.parent = sch->parent; 154 qopt.replace_params.rate = q->rate; 155 qopt.replace_params.max_size = q->max_size; 156 qopt.replace_params.qstats = &sch->qstats; 157 158 dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_TBF, &qopt); 159 } 160 161 static void tbf_offload_destroy(struct Qdisc *sch) 162 { 163 struct net_device *dev = qdisc_dev(sch); 164 struct tc_tbf_qopt_offload qopt; 165 166 if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc) 167 return; 168 169 qopt.command = TC_TBF_DESTROY; 170 qopt.handle = sch->handle; 171 qopt.parent = sch->parent; 172 dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_TBF, &qopt); 173 } 174 175 static int tbf_offload_dump(struct Qdisc *sch) 176 { 177 struct tc_tbf_qopt_offload qopt; 178 179 qopt.command = TC_TBF_STATS; 180 qopt.handle = sch->handle; 181 qopt.parent = sch->parent; 182 qopt.stats.bstats = &sch->bstats; 183 qopt.stats.qstats = &sch->qstats; 184 185 return qdisc_offload_dump_helper(sch, TC_SETUP_QDISC_TBF, &qopt); 186 } 187 188 static void tbf_offload_graft(struct Qdisc *sch, struct Qdisc *new, 189 struct Qdisc *old, struct netlink_ext_ack *extack) 190 { 191 struct tc_tbf_qopt_offload graft_offload = { 192 .handle = sch->handle, 193 .parent = sch->parent, 194 .child_handle = new->handle, 195 .command = TC_TBF_GRAFT, 196 }; 197 198 qdisc_offload_graft_helper(qdisc_dev(sch), sch, new, old, 199 TC_SETUP_QDISC_TBF, &graft_offload, extack); 200 } 201 202 /* GSO packet is too big, segment it so that tbf can transmit 203 * each segment in time 204 */ 205 static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch, 206 struct sk_buff **to_free) 207 { 208 struct tbf_sched_data *q = qdisc_priv(sch); 209 struct sk_buff *segs, *nskb; 210 netdev_features_t features = netif_skb_features(skb); 211 unsigned int len = 0, prev_len = qdisc_pkt_len(skb), seg_len; 212 int ret, nb; 213 214 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK); 215 216 if (IS_ERR_OR_NULL(segs)) 217 return qdisc_drop(skb, sch, to_free); 218 219 nb = 0; 220 skb_list_walk_safe(segs, segs, nskb) { 221 skb_mark_not_on_list(segs); 222 seg_len = segs->len; 223 qdisc_skb_cb(segs)->pkt_len = seg_len; 224 ret = qdisc_enqueue(segs, q->qdisc, to_free); 225 if (ret != NET_XMIT_SUCCESS) { 226 if (net_xmit_drop_count(ret)) 227 qdisc_qstats_drop(sch); 228 } else { 229 nb++; 230 len += seg_len; 231 } 232 } 233 sch->q.qlen += nb; 234 sch->qstats.backlog += len; 235 if (nb > 0) { 236 qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len); 237 consume_skb(skb); 238 return NET_XMIT_SUCCESS; 239 } 240 241 kfree_skb(skb); 242 return NET_XMIT_DROP; 243 } 244 245 static int tbf_enqueue(struct sk_buff *skb, struct Qdisc *sch, 246 struct sk_buff **to_free) 247 { 248 struct tbf_sched_data *q = qdisc_priv(sch); 249 unsigned int len = qdisc_pkt_len(skb); 250 int ret; 251 252 if (qdisc_pkt_len(skb) > q->max_size) { 253 if (skb_is_gso(skb) && 254 skb_gso_validate_mac_len(skb, q->max_size)) 255 return tbf_segment(skb, sch, to_free); 256 return qdisc_drop(skb, sch, to_free); 257 } 258 ret = qdisc_enqueue(skb, q->qdisc, to_free); 259 if (ret != NET_XMIT_SUCCESS) { 260 if (net_xmit_drop_count(ret)) 261 qdisc_qstats_drop(sch); 262 return ret; 263 } 264 265 sch->qstats.backlog += len; 266 sch->q.qlen++; 267 return NET_XMIT_SUCCESS; 268 } 269 270 static bool tbf_peak_present(const struct tbf_sched_data *q) 271 { 272 return q->peak.rate_bytes_ps; 273 } 274 275 static struct sk_buff *tbf_dequeue(struct Qdisc *sch) 276 { 277 struct tbf_sched_data *q = qdisc_priv(sch); 278 struct sk_buff *skb; 279 280 skb = q->qdisc->ops->peek(q->qdisc); 281 282 if (skb) { 283 s64 now; 284 s64 toks; 285 s64 ptoks = 0; 286 unsigned int len = qdisc_pkt_len(skb); 287 288 now = ktime_get_ns(); 289 toks = min_t(s64, now - q->t_c, q->buffer); 290 291 if (tbf_peak_present(q)) { 292 ptoks = toks + q->ptokens; 293 if (ptoks > q->mtu) 294 ptoks = q->mtu; 295 ptoks -= (s64) psched_l2t_ns(&q->peak, len); 296 } 297 toks += q->tokens; 298 if (toks > q->buffer) 299 toks = q->buffer; 300 toks -= (s64) psched_l2t_ns(&q->rate, len); 301 302 if ((toks|ptoks) >= 0) { 303 skb = qdisc_dequeue_peeked(q->qdisc); 304 if (unlikely(!skb)) 305 return NULL; 306 307 q->t_c = now; 308 q->tokens = toks; 309 q->ptokens = ptoks; 310 qdisc_qstats_backlog_dec(sch, skb); 311 sch->q.qlen--; 312 qdisc_bstats_update(sch, skb); 313 return skb; 314 } 315 316 qdisc_watchdog_schedule_ns(&q->watchdog, 317 now + max_t(long, -toks, -ptoks)); 318 319 /* Maybe we have a shorter packet in the queue, 320 which can be sent now. It sounds cool, 321 but, however, this is wrong in principle. 322 We MUST NOT reorder packets under these circumstances. 323 324 Really, if we split the flow into independent 325 subflows, it would be a very good solution. 326 This is the main idea of all FQ algorithms 327 (cf. CSZ, HPFQ, HFSC) 328 */ 329 330 qdisc_qstats_overlimit(sch); 331 } 332 return NULL; 333 } 334 335 static void tbf_reset(struct Qdisc *sch) 336 { 337 struct tbf_sched_data *q = qdisc_priv(sch); 338 339 qdisc_reset(q->qdisc); 340 q->t_c = ktime_get_ns(); 341 q->tokens = q->buffer; 342 q->ptokens = q->mtu; 343 qdisc_watchdog_cancel(&q->watchdog); 344 } 345 346 static const struct nla_policy tbf_policy[TCA_TBF_MAX + 1] = { 347 [TCA_TBF_PARMS] = { .len = sizeof(struct tc_tbf_qopt) }, 348 [TCA_TBF_RTAB] = { .type = NLA_BINARY, .len = TC_RTAB_SIZE }, 349 [TCA_TBF_PTAB] = { .type = NLA_BINARY, .len = TC_RTAB_SIZE }, 350 [TCA_TBF_RATE64] = { .type = NLA_U64 }, 351 [TCA_TBF_PRATE64] = { .type = NLA_U64 }, 352 [TCA_TBF_BURST] = { .type = NLA_U32 }, 353 [TCA_TBF_PBURST] = { .type = NLA_U32 }, 354 }; 355 356 static int tbf_change(struct Qdisc *sch, struct nlattr *opt, 357 struct netlink_ext_ack *extack) 358 { 359 int err; 360 struct tbf_sched_data *q = qdisc_priv(sch); 361 struct nlattr *tb[TCA_TBF_MAX + 1]; 362 struct tc_tbf_qopt *qopt; 363 struct Qdisc *child = NULL; 364 struct Qdisc *old = NULL; 365 struct psched_ratecfg rate; 366 struct psched_ratecfg peak; 367 u64 max_size; 368 s64 buffer, mtu; 369 u64 rate64 = 0, prate64 = 0; 370 371 err = nla_parse_nested_deprecated(tb, TCA_TBF_MAX, opt, tbf_policy, 372 NULL); 373 if (err < 0) 374 return err; 375 376 err = -EINVAL; 377 if (tb[TCA_TBF_PARMS] == NULL) 378 goto done; 379 380 qopt = nla_data(tb[TCA_TBF_PARMS]); 381 if (qopt->rate.linklayer == TC_LINKLAYER_UNAWARE) 382 qdisc_put_rtab(qdisc_get_rtab(&qopt->rate, 383 tb[TCA_TBF_RTAB], 384 NULL)); 385 386 if (qopt->peakrate.linklayer == TC_LINKLAYER_UNAWARE) 387 qdisc_put_rtab(qdisc_get_rtab(&qopt->peakrate, 388 tb[TCA_TBF_PTAB], 389 NULL)); 390 391 buffer = min_t(u64, PSCHED_TICKS2NS(qopt->buffer), ~0U); 392 mtu = min_t(u64, PSCHED_TICKS2NS(qopt->mtu), ~0U); 393 394 if (tb[TCA_TBF_RATE64]) 395 rate64 = nla_get_u64(tb[TCA_TBF_RATE64]); 396 psched_ratecfg_precompute(&rate, &qopt->rate, rate64); 397 398 if (tb[TCA_TBF_BURST]) { 399 max_size = nla_get_u32(tb[TCA_TBF_BURST]); 400 buffer = psched_l2t_ns(&rate, max_size); 401 } else { 402 max_size = min_t(u64, psched_ns_t2l(&rate, buffer), ~0U); 403 } 404 405 if (qopt->peakrate.rate) { 406 if (tb[TCA_TBF_PRATE64]) 407 prate64 = nla_get_u64(tb[TCA_TBF_PRATE64]); 408 psched_ratecfg_precompute(&peak, &qopt->peakrate, prate64); 409 if (peak.rate_bytes_ps <= rate.rate_bytes_ps) { 410 pr_warn_ratelimited("sch_tbf: peakrate %llu is lower than or equals to rate %llu !\n", 411 peak.rate_bytes_ps, rate.rate_bytes_ps); 412 err = -EINVAL; 413 goto done; 414 } 415 416 if (tb[TCA_TBF_PBURST]) { 417 u32 pburst = nla_get_u32(tb[TCA_TBF_PBURST]); 418 max_size = min_t(u32, max_size, pburst); 419 mtu = psched_l2t_ns(&peak, pburst); 420 } else { 421 max_size = min_t(u64, max_size, psched_ns_t2l(&peak, mtu)); 422 } 423 } else { 424 memset(&peak, 0, sizeof(peak)); 425 } 426 427 if (max_size < psched_mtu(qdisc_dev(sch))) 428 pr_warn_ratelimited("sch_tbf: burst %llu is lower than device %s mtu (%u) !\n", 429 max_size, qdisc_dev(sch)->name, 430 psched_mtu(qdisc_dev(sch))); 431 432 if (!max_size) { 433 err = -EINVAL; 434 goto done; 435 } 436 437 if (q->qdisc != &noop_qdisc) { 438 err = fifo_set_limit(q->qdisc, qopt->limit); 439 if (err) 440 goto done; 441 } else if (qopt->limit > 0) { 442 child = fifo_create_dflt(sch, &bfifo_qdisc_ops, qopt->limit, 443 extack); 444 if (IS_ERR(child)) { 445 err = PTR_ERR(child); 446 goto done; 447 } 448 449 /* child is fifo, no need to check for noop_qdisc */ 450 qdisc_hash_add(child, true); 451 } 452 453 sch_tree_lock(sch); 454 if (child) { 455 qdisc_tree_flush_backlog(q->qdisc); 456 old = q->qdisc; 457 q->qdisc = child; 458 } 459 q->limit = qopt->limit; 460 if (tb[TCA_TBF_PBURST]) 461 q->mtu = mtu; 462 else 463 q->mtu = PSCHED_TICKS2NS(qopt->mtu); 464 q->max_size = max_size; 465 if (tb[TCA_TBF_BURST]) 466 q->buffer = buffer; 467 else 468 q->buffer = PSCHED_TICKS2NS(qopt->buffer); 469 q->tokens = q->buffer; 470 q->ptokens = q->mtu; 471 472 memcpy(&q->rate, &rate, sizeof(struct psched_ratecfg)); 473 memcpy(&q->peak, &peak, sizeof(struct psched_ratecfg)); 474 475 sch_tree_unlock(sch); 476 qdisc_put(old); 477 err = 0; 478 479 tbf_offload_change(sch); 480 done: 481 return err; 482 } 483 484 static int tbf_init(struct Qdisc *sch, struct nlattr *opt, 485 struct netlink_ext_ack *extack) 486 { 487 struct tbf_sched_data *q = qdisc_priv(sch); 488 489 qdisc_watchdog_init(&q->watchdog, sch); 490 q->qdisc = &noop_qdisc; 491 492 if (!opt) 493 return -EINVAL; 494 495 q->t_c = ktime_get_ns(); 496 497 return tbf_change(sch, opt, extack); 498 } 499 500 static void tbf_destroy(struct Qdisc *sch) 501 { 502 struct tbf_sched_data *q = qdisc_priv(sch); 503 504 qdisc_watchdog_cancel(&q->watchdog); 505 tbf_offload_destroy(sch); 506 qdisc_put(q->qdisc); 507 } 508 509 static int tbf_dump(struct Qdisc *sch, struct sk_buff *skb) 510 { 511 struct tbf_sched_data *q = qdisc_priv(sch); 512 struct nlattr *nest; 513 struct tc_tbf_qopt opt; 514 int err; 515 516 err = tbf_offload_dump(sch); 517 if (err) 518 return err; 519 520 nest = nla_nest_start_noflag(skb, TCA_OPTIONS); 521 if (nest == NULL) 522 goto nla_put_failure; 523 524 opt.limit = q->limit; 525 psched_ratecfg_getrate(&opt.rate, &q->rate); 526 if (tbf_peak_present(q)) 527 psched_ratecfg_getrate(&opt.peakrate, &q->peak); 528 else 529 memset(&opt.peakrate, 0, sizeof(opt.peakrate)); 530 opt.mtu = PSCHED_NS2TICKS(q->mtu); 531 opt.buffer = PSCHED_NS2TICKS(q->buffer); 532 if (nla_put(skb, TCA_TBF_PARMS, sizeof(opt), &opt)) 533 goto nla_put_failure; 534 if (q->rate.rate_bytes_ps >= (1ULL << 32) && 535 nla_put_u64_64bit(skb, TCA_TBF_RATE64, q->rate.rate_bytes_ps, 536 TCA_TBF_PAD)) 537 goto nla_put_failure; 538 if (tbf_peak_present(q) && 539 q->peak.rate_bytes_ps >= (1ULL << 32) && 540 nla_put_u64_64bit(skb, TCA_TBF_PRATE64, q->peak.rate_bytes_ps, 541 TCA_TBF_PAD)) 542 goto nla_put_failure; 543 544 return nla_nest_end(skb, nest); 545 546 nla_put_failure: 547 nla_nest_cancel(skb, nest); 548 return -1; 549 } 550 551 static int tbf_dump_class(struct Qdisc *sch, unsigned long cl, 552 struct sk_buff *skb, struct tcmsg *tcm) 553 { 554 struct tbf_sched_data *q = qdisc_priv(sch); 555 556 tcm->tcm_handle |= TC_H_MIN(1); 557 tcm->tcm_info = q->qdisc->handle; 558 559 return 0; 560 } 561 562 static int tbf_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, 563 struct Qdisc **old, struct netlink_ext_ack *extack) 564 { 565 struct tbf_sched_data *q = qdisc_priv(sch); 566 567 if (new == NULL) 568 new = &noop_qdisc; 569 570 *old = qdisc_replace(sch, new, &q->qdisc); 571 572 tbf_offload_graft(sch, new, *old, extack); 573 return 0; 574 } 575 576 static struct Qdisc *tbf_leaf(struct Qdisc *sch, unsigned long arg) 577 { 578 struct tbf_sched_data *q = qdisc_priv(sch); 579 return q->qdisc; 580 } 581 582 static unsigned long tbf_find(struct Qdisc *sch, u32 classid) 583 { 584 return 1; 585 } 586 587 static void tbf_walk(struct Qdisc *sch, struct qdisc_walker *walker) 588 { 589 if (!walker->stop) { 590 tc_qdisc_stats_dump(sch, 1, walker); 591 } 592 } 593 594 static const struct Qdisc_class_ops tbf_class_ops = { 595 .graft = tbf_graft, 596 .leaf = tbf_leaf, 597 .find = tbf_find, 598 .walk = tbf_walk, 599 .dump = tbf_dump_class, 600 }; 601 602 static struct Qdisc_ops tbf_qdisc_ops __read_mostly = { 603 .next = NULL, 604 .cl_ops = &tbf_class_ops, 605 .id = "tbf", 606 .priv_size = sizeof(struct tbf_sched_data), 607 .enqueue = tbf_enqueue, 608 .dequeue = tbf_dequeue, 609 .peek = qdisc_peek_dequeued, 610 .init = tbf_init, 611 .reset = tbf_reset, 612 .destroy = tbf_destroy, 613 .change = tbf_change, 614 .dump = tbf_dump, 615 .owner = THIS_MODULE, 616 }; 617 MODULE_ALIAS_NET_SCH("tbf"); 618 619 static int __init tbf_module_init(void) 620 { 621 return register_qdisc(&tbf_qdisc_ops); 622 } 623 624 static void __exit tbf_module_exit(void) 625 { 626 unregister_qdisc(&tbf_qdisc_ops); 627 } 628 module_init(tbf_module_init) 629 module_exit(tbf_module_exit) 630 MODULE_LICENSE("GPL"); 631 MODULE_DESCRIPTION("Token Bucket Filter qdisc"); 632