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);
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 qdisc_skb_cb(segs)->pkt_len = segs->len;
223 len += segs->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 }
231 }
232 sch->q.qlen += nb;
233 if (nb > 1)
234 qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len);
235 consume_skb(skb);
236 return nb > 0 ? NET_XMIT_SUCCESS : NET_XMIT_DROP;
237 }
238
239 static int tbf_enqueue(struct sk_buff *skb, struct Qdisc *sch,
240 struct sk_buff **to_free)
241 {
242 struct tbf_sched_data *q = qdisc_priv(sch);
243 unsigned int len = qdisc_pkt_len(skb);
244 int ret;
245
246 if (qdisc_pkt_len(skb) > q->max_size) {
247 if (skb_is_gso(skb) &&
248 skb_gso_validate_mac_len(skb, q->max_size))
249 return tbf_segment(skb, sch, to_free);
250 return qdisc_drop(skb, sch, to_free);
251 }
252 ret = qdisc_enqueue(skb, q->qdisc, to_free);
253 if (ret != NET_XMIT_SUCCESS) {
254 if (net_xmit_drop_count(ret))
255 qdisc_qstats_drop(sch);
256 return ret;
257 }
258
259 sch->qstats.backlog += len;
260 sch->q.qlen++;
261 return NET_XMIT_SUCCESS;
262 }
263
264 static bool tbf_peak_present(const struct tbf_sched_data *q)
265 {
266 return q->peak.rate_bytes_ps;
267 }
268
269 static struct sk_buff *tbf_dequeue(struct Qdisc *sch)
270 {
271 struct tbf_sched_data *q = qdisc_priv(sch);
272 struct sk_buff *skb;
273
274 skb = q->qdisc->ops->peek(q->qdisc);
275
276 if (skb) {
277 s64 now;
278 s64 toks;
279 s64 ptoks = 0;
280 unsigned int len = qdisc_pkt_len(skb);
281
282 now = ktime_get_ns();
283 toks = min_t(s64, now - q->t_c, q->buffer);
284
285 if (tbf_peak_present(q)) {
286 ptoks = toks + q->ptokens;
287 if (ptoks > q->mtu)
288 ptoks = q->mtu;
289 ptoks -= (s64) psched_l2t_ns(&q->peak, len);
290 }
291 toks += q->tokens;
292 if (toks > q->buffer)
293 toks = q->buffer;
294 toks -= (s64) psched_l2t_ns(&q->rate, len);
295
296 if ((toks|ptoks) >= 0) {
297 skb = qdisc_dequeue_peeked(q->qdisc);
298 if (unlikely(!skb))
299 return NULL;
300
301 q->t_c = now;
302 q->tokens = toks;
303 q->ptokens = ptoks;
304 qdisc_qstats_backlog_dec(sch, skb);
305 sch->q.qlen--;
306 qdisc_bstats_update(sch, skb);
307 return skb;
308 }
309
310 qdisc_watchdog_schedule_ns(&q->watchdog,
311 now + max_t(long, -toks, -ptoks));
312
313 /* Maybe we have a shorter packet in the queue,
314 which can be sent now. It sounds cool,
315 but, however, this is wrong in principle.
316 We MUST NOT reorder packets under these circumstances.
317
318 Really, if we split the flow into independent
319 subflows, it would be a very good solution.
320 This is the main idea of all FQ algorithms
321 (cf. CSZ, HPFQ, HFSC)
322 */
323
324 qdisc_qstats_overlimit(sch);
325 }
326 return NULL;
327 }
328
329 static void tbf_reset(struct Qdisc *sch)
330 {
331 struct tbf_sched_data *q = qdisc_priv(sch);
332
333 qdisc_reset(q->qdisc);
334 q->t_c = ktime_get_ns();
335 q->tokens = q->buffer;
336 q->ptokens = q->mtu;
337 qdisc_watchdog_cancel(&q->watchdog);
338 }
339
340 static const struct nla_policy tbf_policy[TCA_TBF_MAX + 1] = {
341 [TCA_TBF_PARMS] = { .len = sizeof(struct tc_tbf_qopt) },
342 [TCA_TBF_RTAB] = { .type = NLA_BINARY, .len = TC_RTAB_SIZE },
343 [TCA_TBF_PTAB] = { .type = NLA_BINARY, .len = TC_RTAB_SIZE },
344 [TCA_TBF_RATE64] = { .type = NLA_U64 },
345 [TCA_TBF_PRATE64] = { .type = NLA_U64 },
346 [TCA_TBF_BURST] = { .type = NLA_U32 },
347 [TCA_TBF_PBURST] = { .type = NLA_U32 },
348 };
349
350 static int tbf_change(struct Qdisc *sch, struct nlattr *opt,
351 struct netlink_ext_ack *extack)
352 {
353 int err;
354 struct tbf_sched_data *q = qdisc_priv(sch);
355 struct nlattr *tb[TCA_TBF_MAX + 1];
356 struct tc_tbf_qopt *qopt;
357 struct Qdisc *child = NULL;
358 struct Qdisc *old = NULL;
359 struct psched_ratecfg rate;
360 struct psched_ratecfg peak;
361 u64 max_size;
362 s64 buffer, mtu;
363 u64 rate64 = 0, prate64 = 0;
364
365 err = nla_parse_nested_deprecated(tb, TCA_TBF_MAX, opt, tbf_policy,
366 NULL);
367 if (err < 0)
368 return err;
369
370 err = -EINVAL;
371 if (tb[TCA_TBF_PARMS] == NULL)
372 goto done;
373
374 qopt = nla_data(tb[TCA_TBF_PARMS]);
375 if (qopt->rate.linklayer == TC_LINKLAYER_UNAWARE)
376 qdisc_put_rtab(qdisc_get_rtab(&qopt->rate,
377 tb[TCA_TBF_RTAB],
378 NULL));
379
380 if (qopt->peakrate.linklayer == TC_LINKLAYER_UNAWARE)
381 qdisc_put_rtab(qdisc_get_rtab(&qopt->peakrate,
382 tb[TCA_TBF_PTAB],
383 NULL));
384
385 buffer = min_t(u64, PSCHED_TICKS2NS(qopt->buffer), ~0U);
386 mtu = min_t(u64, PSCHED_TICKS2NS(qopt->mtu), ~0U);
387
388 if (tb[TCA_TBF_RATE64])
389 rate64 = nla_get_u64(tb[TCA_TBF_RATE64]);
390 psched_ratecfg_precompute(&rate, &qopt->rate, rate64);
391
392 if (tb[TCA_TBF_BURST]) {
393 max_size = nla_get_u32(tb[TCA_TBF_BURST]);
394 buffer = psched_l2t_ns(&rate, max_size);
395 } else {
396 max_size = min_t(u64, psched_ns_t2l(&rate, buffer), ~0U);
397 }
398
399 if (qopt->peakrate.rate) {
400 if (tb[TCA_TBF_PRATE64])
401 prate64 = nla_get_u64(tb[TCA_TBF_PRATE64]);
402 psched_ratecfg_precompute(&peak, &qopt->peakrate, prate64);
403 if (peak.rate_bytes_ps <= rate.rate_bytes_ps) {
404 pr_warn_ratelimited("sch_tbf: peakrate %llu is lower than or equals to rate %llu !\n",
405 peak.rate_bytes_ps, rate.rate_bytes_ps);
406 err = -EINVAL;
407 goto done;
408 }
409
410 if (tb[TCA_TBF_PBURST]) {
411 u32 pburst = nla_get_u32(tb[TCA_TBF_PBURST]);
412 max_size = min_t(u32, max_size, pburst);
413 mtu = psched_l2t_ns(&peak, pburst);
414 } else {
415 max_size = min_t(u64, max_size, psched_ns_t2l(&peak, mtu));
416 }
417 } else {
418 memset(&peak, 0, sizeof(peak));
419 }
420
421 if (max_size < psched_mtu(qdisc_dev(sch)))
422 pr_warn_ratelimited("sch_tbf: burst %llu is lower than device %s mtu (%u) !\n",
423 max_size, qdisc_dev(sch)->name,
424 psched_mtu(qdisc_dev(sch)));
425
426 if (!max_size) {
427 err = -EINVAL;
428 goto done;
429 }
430
431 if (q->qdisc != &noop_qdisc) {
432 err = fifo_set_limit(q->qdisc, qopt->limit);
433 if (err)
434 goto done;
435 } else if (qopt->limit > 0) {
436 child = fifo_create_dflt(sch, &bfifo_qdisc_ops, qopt->limit,
437 extack);
438 if (IS_ERR(child)) {
439 err = PTR_ERR(child);
440 goto done;
441 }
442
443 /* child is fifo, no need to check for noop_qdisc */
444 qdisc_hash_add(child, true);
445 }
446
447 sch_tree_lock(sch);
448 if (child) {
449 qdisc_tree_flush_backlog(q->qdisc);
450 old = q->qdisc;
451 q->qdisc = child;
452 }
453 q->limit = qopt->limit;
454 if (tb[TCA_TBF_PBURST])
455 q->mtu = mtu;
456 else
457 q->mtu = PSCHED_TICKS2NS(qopt->mtu);
458 q->max_size = max_size;
459 if (tb[TCA_TBF_BURST])
460 q->buffer = buffer;
461 else
462 q->buffer = PSCHED_TICKS2NS(qopt->buffer);
463 q->tokens = q->buffer;
464 q->ptokens = q->mtu;
465
466 memcpy(&q->rate, &rate, sizeof(struct psched_ratecfg));
467 memcpy(&q->peak, &peak, sizeof(struct psched_ratecfg));
468
469 sch_tree_unlock(sch);
470 qdisc_put(old);
471 err = 0;
472
473 tbf_offload_change(sch);
474 done:
475 return err;
476 }
477
478 static int tbf_init(struct Qdisc *sch, struct nlattr *opt,
479 struct netlink_ext_ack *extack)
480 {
481 struct tbf_sched_data *q = qdisc_priv(sch);
482
483 qdisc_watchdog_init(&q->watchdog, sch);
484 q->qdisc = &noop_qdisc;
485
486 if (!opt)
487 return -EINVAL;
488
489 q->t_c = ktime_get_ns();
490
491 return tbf_change(sch, opt, extack);
492 }
493
494 static void tbf_destroy(struct Qdisc *sch)
495 {
496 struct tbf_sched_data *q = qdisc_priv(sch);
497
498 qdisc_watchdog_cancel(&q->watchdog);
499 tbf_offload_destroy(sch);
500 qdisc_put(q->qdisc);
501 }
502
503 static int tbf_dump(struct Qdisc *sch, struct sk_buff *skb)
504 {
505 struct tbf_sched_data *q = qdisc_priv(sch);
506 struct nlattr *nest;
507 struct tc_tbf_qopt opt;
508 int err;
509
510 err = tbf_offload_dump(sch);
511 if (err)
512 return err;
513
514 nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
515 if (nest == NULL)
516 goto nla_put_failure;
517
518 opt.limit = q->limit;
519 psched_ratecfg_getrate(&opt.rate, &q->rate);
520 if (tbf_peak_present(q))
521 psched_ratecfg_getrate(&opt.peakrate, &q->peak);
522 else
523 memset(&opt.peakrate, 0, sizeof(opt.peakrate));
524 opt.mtu = PSCHED_NS2TICKS(q->mtu);
525 opt.buffer = PSCHED_NS2TICKS(q->buffer);
526 if (nla_put(skb, TCA_TBF_PARMS, sizeof(opt), &opt))
527 goto nla_put_failure;
528 if (q->rate.rate_bytes_ps >= (1ULL << 32) &&
529 nla_put_u64_64bit(skb, TCA_TBF_RATE64, q->rate.rate_bytes_ps,
530 TCA_TBF_PAD))
531 goto nla_put_failure;
532 if (tbf_peak_present(q) &&
533 q->peak.rate_bytes_ps >= (1ULL << 32) &&
534 nla_put_u64_64bit(skb, TCA_TBF_PRATE64, q->peak.rate_bytes_ps,
535 TCA_TBF_PAD))
536 goto nla_put_failure;
537
538 return nla_nest_end(skb, nest);
539
540 nla_put_failure:
541 nla_nest_cancel(skb, nest);
542 return -1;
543 }
544
545 static int tbf_dump_class(struct Qdisc *sch, unsigned long cl,
546 struct sk_buff *skb, struct tcmsg *tcm)
547 {
548 struct tbf_sched_data *q = qdisc_priv(sch);
549
550 tcm->tcm_handle |= TC_H_MIN(1);
551 tcm->tcm_info = q->qdisc->handle;
552
553 return 0;
554 }
555
556 static int tbf_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
557 struct Qdisc **old, struct netlink_ext_ack *extack)
558 {
559 struct tbf_sched_data *q = qdisc_priv(sch);
560
561 if (new == NULL)
562 new = &noop_qdisc;
563
564 *old = qdisc_replace(sch, new, &q->qdisc);
565
566 tbf_offload_graft(sch, new, *old, extack);
567 return 0;
568 }
569
570 static struct Qdisc *tbf_leaf(struct Qdisc *sch, unsigned long arg)
571 {
572 struct tbf_sched_data *q = qdisc_priv(sch);
573 return q->qdisc;
574 }
575
576 static unsigned long tbf_find(struct Qdisc *sch, u32 classid)
577 {
578 return 1;
579 }
580
581 static void tbf_walk(struct Qdisc *sch, struct qdisc_walker *walker)
582 {
583 if (!walker->stop) {
584 tc_qdisc_stats_dump(sch, 1, walker);
585 }
586 }
587
588 static const struct Qdisc_class_ops tbf_class_ops = {
589 .graft = tbf_graft,
590 .leaf = tbf_leaf,
591 .find = tbf_find,
592 .walk = tbf_walk,
593 .dump = tbf_dump_class,
594 };
595
596 static struct Qdisc_ops tbf_qdisc_ops __read_mostly = {
597 .next = NULL,
598 .cl_ops = &tbf_class_ops,
599 .id = "tbf",
600 .priv_size = sizeof(struct tbf_sched_data),
601 .enqueue = tbf_enqueue,
602 .dequeue = tbf_dequeue,
603 .peek = qdisc_peek_dequeued,
604 .init = tbf_init,
605 .reset = tbf_reset,
606 .destroy = tbf_destroy,
607 .change = tbf_change,
608 .dump = tbf_dump,
609 .owner = THIS_MODULE,
610 };
611 MODULE_ALIAS_NET_SCH("tbf");
612
613 static int __init tbf_module_init(void)
614 {
615 return register_qdisc(&tbf_qdisc_ops);
616 }
617
618 static void __exit tbf_module_exit(void)
619 {
620 unregister_qdisc(&tbf_qdisc_ops);
621 }
622 module_init(tbf_module_init)
623 module_exit(tbf_module_exit)
624 MODULE_LICENSE("GPL");
625 MODULE_DESCRIPTION("Token Bucket Filter qdisc");
626
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.