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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
98struct 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 */
119static 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
142static 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
161static 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
175static 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
188static 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 */
205static 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
245static 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
270static bool tbf_peak_present(const struct tbf_sched_data *q)
271{
272 return q->peak.rate_bytes_ps;
273}
274
275static 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
335static 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
346static 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
356static 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);
480done:
481 return err;
482}
483
484static 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
500static 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
509static 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
546nla_put_failure:
547 nla_nest_cancel(skb, nest);
548 return -1;
549}
550
551static 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
562static 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
576static 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
582static unsigned long tbf_find(struct Qdisc *sch, u32 classid)
583{
584 return 1;
585}
586
587static 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
594static 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
602static 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};
617MODULE_ALIAS_NET_SCH("tbf");
618
619static int __init tbf_module_init(void)
620{
621 return register_qdisc(&tbf_qdisc_ops);
622}
623
624static void __exit tbf_module_exit(void)
625{
626 unregister_qdisc(&tbf_qdisc_ops);
627}
628module_init(tbf_module_init)
629module_exit(tbf_module_exit)
630MODULE_LICENSE("GPL");
631MODULE_DESCRIPTION("Token Bucket Filter qdisc");
1/*
2 * net/sched/sch_tbf.c Token Bucket Filter queue.
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 * Dmitry Torokhov <dtor@mail.ru> - allow attaching inner qdiscs -
11 * original idea by Martin Devera
12 *
13 */
14
15#include <linux/module.h>
16#include <linux/types.h>
17#include <linux/kernel.h>
18#include <linux/string.h>
19#include <linux/errno.h>
20#include <linux/skbuff.h>
21#include <net/netlink.h>
22#include <net/sch_generic.h>
23#include <net/pkt_sched.h>
24
25
26/* Simple Token Bucket Filter.
27 =======================================
28
29 SOURCE.
30 -------
31
32 None.
33
34 Description.
35 ------------
36
37 A data flow obeys TBF with rate R and depth B, if for any
38 time interval t_i...t_f the number of transmitted bits
39 does not exceed B + R*(t_f-t_i).
40
41 Packetized version of this definition:
42 The sequence of packets of sizes s_i served at moments t_i
43 obeys TBF, if for any i<=k:
44
45 s_i+....+s_k <= B + R*(t_k - t_i)
46
47 Algorithm.
48 ----------
49
50 Let N(t_i) be B/R initially and N(t) grow continuously with time as:
51
52 N(t+delta) = min{B/R, N(t) + delta}
53
54 If the first packet in queue has length S, it may be
55 transmitted only at the time t_* when S/R <= N(t_*),
56 and in this case N(t) jumps:
57
58 N(t_* + 0) = N(t_* - 0) - S/R.
59
60
61
62 Actually, QoS requires two TBF to be applied to a data stream.
63 One of them controls steady state burst size, another
64 one with rate P (peak rate) and depth M (equal to link MTU)
65 limits bursts at a smaller time scale.
66
67 It is easy to see that P>R, and B>M. If P is infinity, this double
68 TBF is equivalent to a single one.
69
70 When TBF works in reshaping mode, latency is estimated as:
71
72 lat = max ((L-B)/R, (L-M)/P)
73
74
75 NOTES.
76 ------
77
78 If TBF throttles, it starts a watchdog timer, which will wake it up
79 when it is ready to transmit.
80 Note that the minimal timer resolution is 1/HZ.
81 If no new packets arrive during this period,
82 or if the device is not awaken by EOI for some previous packet,
83 TBF can stop its activity for 1/HZ.
84
85
86 This means, that with depth B, the maximal rate is
87
88 R_crit = B*HZ
89
90 F.e. for 10Mbit ethernet and HZ=100 the minimal allowed B is ~10Kbytes.
91
92 Note that the peak rate TBF is much more tough: with MTU 1500
93 P_crit = 150Kbytes/sec. So, if you need greater peak
94 rates, use alpha with HZ=1000 :-)
95
96 With classful TBF, limit is just kept for backwards compatibility.
97 It is passed to the default bfifo qdisc - if the inner qdisc is
98 changed the limit is not effective anymore.
99*/
100
101struct tbf_sched_data {
102/* Parameters */
103 u32 limit; /* Maximal length of backlog: bytes */
104 u32 max_size;
105 s64 buffer; /* Token bucket depth/rate: MUST BE >= MTU/B */
106 s64 mtu;
107 struct psched_ratecfg rate;
108 struct psched_ratecfg peak;
109
110/* Variables */
111 s64 tokens; /* Current number of B tokens */
112 s64 ptokens; /* Current number of P tokens */
113 s64 t_c; /* Time check-point */
114 struct Qdisc *qdisc; /* Inner qdisc, default - bfifo queue */
115 struct qdisc_watchdog watchdog; /* Watchdog timer */
116};
117
118
119/* Time to Length, convert time in ns to length in bytes
120 * to determinate how many bytes can be sent in given time.
121 */
122static u64 psched_ns_t2l(const struct psched_ratecfg *r,
123 u64 time_in_ns)
124{
125 /* The formula is :
126 * len = (time_in_ns * r->rate_bytes_ps) / NSEC_PER_SEC
127 */
128 u64 len = time_in_ns * r->rate_bytes_ps;
129
130 do_div(len, NSEC_PER_SEC);
131
132 if (unlikely(r->linklayer == TC_LINKLAYER_ATM)) {
133 do_div(len, 53);
134 len = len * 48;
135 }
136
137 if (len > r->overhead)
138 len -= r->overhead;
139 else
140 len = 0;
141
142 return len;
143}
144
145/* GSO packet is too big, segment it so that tbf can transmit
146 * each segment in time
147 */
148static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch,
149 struct sk_buff **to_free)
150{
151 struct tbf_sched_data *q = qdisc_priv(sch);
152 struct sk_buff *segs, *nskb;
153 netdev_features_t features = netif_skb_features(skb);
154 unsigned int len = 0, prev_len = qdisc_pkt_len(skb);
155 int ret, nb;
156
157 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
158
159 if (IS_ERR_OR_NULL(segs))
160 return qdisc_drop(skb, sch, to_free);
161
162 nb = 0;
163 while (segs) {
164 nskb = segs->next;
165 segs->next = NULL;
166 qdisc_skb_cb(segs)->pkt_len = segs->len;
167 len += segs->len;
168 ret = qdisc_enqueue(segs, q->qdisc, to_free);
169 if (ret != NET_XMIT_SUCCESS) {
170 if (net_xmit_drop_count(ret))
171 qdisc_qstats_drop(sch);
172 } else {
173 nb++;
174 }
175 segs = nskb;
176 }
177 sch->q.qlen += nb;
178 if (nb > 1)
179 qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len);
180 consume_skb(skb);
181 return nb > 0 ? NET_XMIT_SUCCESS : NET_XMIT_DROP;
182}
183
184static int tbf_enqueue(struct sk_buff *skb, struct Qdisc *sch,
185 struct sk_buff **to_free)
186{
187 struct tbf_sched_data *q = qdisc_priv(sch);
188 int ret;
189
190 if (qdisc_pkt_len(skb) > q->max_size) {
191 if (skb_is_gso(skb) &&
192 skb_gso_validate_mac_len(skb, q->max_size))
193 return tbf_segment(skb, sch, to_free);
194 return qdisc_drop(skb, sch, to_free);
195 }
196 ret = qdisc_enqueue(skb, q->qdisc, to_free);
197 if (ret != NET_XMIT_SUCCESS) {
198 if (net_xmit_drop_count(ret))
199 qdisc_qstats_drop(sch);
200 return ret;
201 }
202
203 qdisc_qstats_backlog_inc(sch, skb);
204 sch->q.qlen++;
205 return NET_XMIT_SUCCESS;
206}
207
208static bool tbf_peak_present(const struct tbf_sched_data *q)
209{
210 return q->peak.rate_bytes_ps;
211}
212
213static struct sk_buff *tbf_dequeue(struct Qdisc *sch)
214{
215 struct tbf_sched_data *q = qdisc_priv(sch);
216 struct sk_buff *skb;
217
218 skb = q->qdisc->ops->peek(q->qdisc);
219
220 if (skb) {
221 s64 now;
222 s64 toks;
223 s64 ptoks = 0;
224 unsigned int len = qdisc_pkt_len(skb);
225
226 now = ktime_get_ns();
227 toks = min_t(s64, now - q->t_c, q->buffer);
228
229 if (tbf_peak_present(q)) {
230 ptoks = toks + q->ptokens;
231 if (ptoks > q->mtu)
232 ptoks = q->mtu;
233 ptoks -= (s64) psched_l2t_ns(&q->peak, len);
234 }
235 toks += q->tokens;
236 if (toks > q->buffer)
237 toks = q->buffer;
238 toks -= (s64) psched_l2t_ns(&q->rate, len);
239
240 if ((toks|ptoks) >= 0) {
241 skb = qdisc_dequeue_peeked(q->qdisc);
242 if (unlikely(!skb))
243 return NULL;
244
245 q->t_c = now;
246 q->tokens = toks;
247 q->ptokens = ptoks;
248 qdisc_qstats_backlog_dec(sch, skb);
249 sch->q.qlen--;
250 qdisc_bstats_update(sch, skb);
251 return skb;
252 }
253
254 qdisc_watchdog_schedule_ns(&q->watchdog,
255 now + max_t(long, -toks, -ptoks));
256
257 /* Maybe we have a shorter packet in the queue,
258 which can be sent now. It sounds cool,
259 but, however, this is wrong in principle.
260 We MUST NOT reorder packets under these circumstances.
261
262 Really, if we split the flow into independent
263 subflows, it would be a very good solution.
264 This is the main idea of all FQ algorithms
265 (cf. CSZ, HPFQ, HFSC)
266 */
267
268 qdisc_qstats_overlimit(sch);
269 }
270 return NULL;
271}
272
273static void tbf_reset(struct Qdisc *sch)
274{
275 struct tbf_sched_data *q = qdisc_priv(sch);
276
277 qdisc_reset(q->qdisc);
278 sch->qstats.backlog = 0;
279 sch->q.qlen = 0;
280 q->t_c = ktime_get_ns();
281 q->tokens = q->buffer;
282 q->ptokens = q->mtu;
283 qdisc_watchdog_cancel(&q->watchdog);
284}
285
286static const struct nla_policy tbf_policy[TCA_TBF_MAX + 1] = {
287 [TCA_TBF_PARMS] = { .len = sizeof(struct tc_tbf_qopt) },
288 [TCA_TBF_RTAB] = { .type = NLA_BINARY, .len = TC_RTAB_SIZE },
289 [TCA_TBF_PTAB] = { .type = NLA_BINARY, .len = TC_RTAB_SIZE },
290 [TCA_TBF_RATE64] = { .type = NLA_U64 },
291 [TCA_TBF_PRATE64] = { .type = NLA_U64 },
292 [TCA_TBF_BURST] = { .type = NLA_U32 },
293 [TCA_TBF_PBURST] = { .type = NLA_U32 },
294};
295
296static int tbf_change(struct Qdisc *sch, struct nlattr *opt,
297 struct netlink_ext_ack *extack)
298{
299 int err;
300 struct tbf_sched_data *q = qdisc_priv(sch);
301 struct nlattr *tb[TCA_TBF_MAX + 1];
302 struct tc_tbf_qopt *qopt;
303 struct Qdisc *child = NULL;
304 struct psched_ratecfg rate;
305 struct psched_ratecfg peak;
306 u64 max_size;
307 s64 buffer, mtu;
308 u64 rate64 = 0, prate64 = 0;
309
310 err = nla_parse_nested(tb, TCA_TBF_MAX, opt, tbf_policy, NULL);
311 if (err < 0)
312 return err;
313
314 err = -EINVAL;
315 if (tb[TCA_TBF_PARMS] == NULL)
316 goto done;
317
318 qopt = nla_data(tb[TCA_TBF_PARMS]);
319 if (qopt->rate.linklayer == TC_LINKLAYER_UNAWARE)
320 qdisc_put_rtab(qdisc_get_rtab(&qopt->rate,
321 tb[TCA_TBF_RTAB],
322 NULL));
323
324 if (qopt->peakrate.linklayer == TC_LINKLAYER_UNAWARE)
325 qdisc_put_rtab(qdisc_get_rtab(&qopt->peakrate,
326 tb[TCA_TBF_PTAB],
327 NULL));
328
329 buffer = min_t(u64, PSCHED_TICKS2NS(qopt->buffer), ~0U);
330 mtu = min_t(u64, PSCHED_TICKS2NS(qopt->mtu), ~0U);
331
332 if (tb[TCA_TBF_RATE64])
333 rate64 = nla_get_u64(tb[TCA_TBF_RATE64]);
334 psched_ratecfg_precompute(&rate, &qopt->rate, rate64);
335
336 if (tb[TCA_TBF_BURST]) {
337 max_size = nla_get_u32(tb[TCA_TBF_BURST]);
338 buffer = psched_l2t_ns(&rate, max_size);
339 } else {
340 max_size = min_t(u64, psched_ns_t2l(&rate, buffer), ~0U);
341 }
342
343 if (qopt->peakrate.rate) {
344 if (tb[TCA_TBF_PRATE64])
345 prate64 = nla_get_u64(tb[TCA_TBF_PRATE64]);
346 psched_ratecfg_precompute(&peak, &qopt->peakrate, prate64);
347 if (peak.rate_bytes_ps <= rate.rate_bytes_ps) {
348 pr_warn_ratelimited("sch_tbf: peakrate %llu is lower than or equals to rate %llu !\n",
349 peak.rate_bytes_ps, rate.rate_bytes_ps);
350 err = -EINVAL;
351 goto done;
352 }
353
354 if (tb[TCA_TBF_PBURST]) {
355 u32 pburst = nla_get_u32(tb[TCA_TBF_PBURST]);
356 max_size = min_t(u32, max_size, pburst);
357 mtu = psched_l2t_ns(&peak, pburst);
358 } else {
359 max_size = min_t(u64, max_size, psched_ns_t2l(&peak, mtu));
360 }
361 } else {
362 memset(&peak, 0, sizeof(peak));
363 }
364
365 if (max_size < psched_mtu(qdisc_dev(sch)))
366 pr_warn_ratelimited("sch_tbf: burst %llu is lower than device %s mtu (%u) !\n",
367 max_size, qdisc_dev(sch)->name,
368 psched_mtu(qdisc_dev(sch)));
369
370 if (!max_size) {
371 err = -EINVAL;
372 goto done;
373 }
374
375 if (q->qdisc != &noop_qdisc) {
376 err = fifo_set_limit(q->qdisc, qopt->limit);
377 if (err)
378 goto done;
379 } else if (qopt->limit > 0) {
380 child = fifo_create_dflt(sch, &bfifo_qdisc_ops, qopt->limit,
381 extack);
382 if (IS_ERR(child)) {
383 err = PTR_ERR(child);
384 goto done;
385 }
386
387 /* child is fifo, no need to check for noop_qdisc */
388 qdisc_hash_add(child, true);
389 }
390
391 sch_tree_lock(sch);
392 if (child) {
393 qdisc_tree_reduce_backlog(q->qdisc, q->qdisc->q.qlen,
394 q->qdisc->qstats.backlog);
395 qdisc_destroy(q->qdisc);
396 q->qdisc = child;
397 }
398 q->limit = qopt->limit;
399 if (tb[TCA_TBF_PBURST])
400 q->mtu = mtu;
401 else
402 q->mtu = PSCHED_TICKS2NS(qopt->mtu);
403 q->max_size = max_size;
404 if (tb[TCA_TBF_BURST])
405 q->buffer = buffer;
406 else
407 q->buffer = PSCHED_TICKS2NS(qopt->buffer);
408 q->tokens = q->buffer;
409 q->ptokens = q->mtu;
410
411 memcpy(&q->rate, &rate, sizeof(struct psched_ratecfg));
412 memcpy(&q->peak, &peak, sizeof(struct psched_ratecfg));
413
414 sch_tree_unlock(sch);
415 err = 0;
416done:
417 return err;
418}
419
420static int tbf_init(struct Qdisc *sch, struct nlattr *opt,
421 struct netlink_ext_ack *extack)
422{
423 struct tbf_sched_data *q = qdisc_priv(sch);
424
425 qdisc_watchdog_init(&q->watchdog, sch);
426 q->qdisc = &noop_qdisc;
427
428 if (!opt)
429 return -EINVAL;
430
431 q->t_c = ktime_get_ns();
432
433 return tbf_change(sch, opt, extack);
434}
435
436static void tbf_destroy(struct Qdisc *sch)
437{
438 struct tbf_sched_data *q = qdisc_priv(sch);
439
440 qdisc_watchdog_cancel(&q->watchdog);
441 qdisc_destroy(q->qdisc);
442}
443
444static int tbf_dump(struct Qdisc *sch, struct sk_buff *skb)
445{
446 struct tbf_sched_data *q = qdisc_priv(sch);
447 struct nlattr *nest;
448 struct tc_tbf_qopt opt;
449
450 sch->qstats.backlog = q->qdisc->qstats.backlog;
451 nest = nla_nest_start(skb, TCA_OPTIONS);
452 if (nest == NULL)
453 goto nla_put_failure;
454
455 opt.limit = q->limit;
456 psched_ratecfg_getrate(&opt.rate, &q->rate);
457 if (tbf_peak_present(q))
458 psched_ratecfg_getrate(&opt.peakrate, &q->peak);
459 else
460 memset(&opt.peakrate, 0, sizeof(opt.peakrate));
461 opt.mtu = PSCHED_NS2TICKS(q->mtu);
462 opt.buffer = PSCHED_NS2TICKS(q->buffer);
463 if (nla_put(skb, TCA_TBF_PARMS, sizeof(opt), &opt))
464 goto nla_put_failure;
465 if (q->rate.rate_bytes_ps >= (1ULL << 32) &&
466 nla_put_u64_64bit(skb, TCA_TBF_RATE64, q->rate.rate_bytes_ps,
467 TCA_TBF_PAD))
468 goto nla_put_failure;
469 if (tbf_peak_present(q) &&
470 q->peak.rate_bytes_ps >= (1ULL << 32) &&
471 nla_put_u64_64bit(skb, TCA_TBF_PRATE64, q->peak.rate_bytes_ps,
472 TCA_TBF_PAD))
473 goto nla_put_failure;
474
475 return nla_nest_end(skb, nest);
476
477nla_put_failure:
478 nla_nest_cancel(skb, nest);
479 return -1;
480}
481
482static int tbf_dump_class(struct Qdisc *sch, unsigned long cl,
483 struct sk_buff *skb, struct tcmsg *tcm)
484{
485 struct tbf_sched_data *q = qdisc_priv(sch);
486
487 tcm->tcm_handle |= TC_H_MIN(1);
488 tcm->tcm_info = q->qdisc->handle;
489
490 return 0;
491}
492
493static int tbf_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
494 struct Qdisc **old, struct netlink_ext_ack *extack)
495{
496 struct tbf_sched_data *q = qdisc_priv(sch);
497
498 if (new == NULL)
499 new = &noop_qdisc;
500
501 *old = qdisc_replace(sch, new, &q->qdisc);
502 return 0;
503}
504
505static struct Qdisc *tbf_leaf(struct Qdisc *sch, unsigned long arg)
506{
507 struct tbf_sched_data *q = qdisc_priv(sch);
508 return q->qdisc;
509}
510
511static unsigned long tbf_find(struct Qdisc *sch, u32 classid)
512{
513 return 1;
514}
515
516static void tbf_walk(struct Qdisc *sch, struct qdisc_walker *walker)
517{
518 if (!walker->stop) {
519 if (walker->count >= walker->skip)
520 if (walker->fn(sch, 1, walker) < 0) {
521 walker->stop = 1;
522 return;
523 }
524 walker->count++;
525 }
526}
527
528static const struct Qdisc_class_ops tbf_class_ops = {
529 .graft = tbf_graft,
530 .leaf = tbf_leaf,
531 .find = tbf_find,
532 .walk = tbf_walk,
533 .dump = tbf_dump_class,
534};
535
536static struct Qdisc_ops tbf_qdisc_ops __read_mostly = {
537 .next = NULL,
538 .cl_ops = &tbf_class_ops,
539 .id = "tbf",
540 .priv_size = sizeof(struct tbf_sched_data),
541 .enqueue = tbf_enqueue,
542 .dequeue = tbf_dequeue,
543 .peek = qdisc_peek_dequeued,
544 .init = tbf_init,
545 .reset = tbf_reset,
546 .destroy = tbf_destroy,
547 .change = tbf_change,
548 .dump = tbf_dump,
549 .owner = THIS_MODULE,
550};
551
552static int __init tbf_module_init(void)
553{
554 return register_qdisc(&tbf_qdisc_ops);
555}
556
557static void __exit tbf_module_exit(void)
558{
559 unregister_qdisc(&tbf_qdisc_ops);
560}
561module_init(tbf_module_init)
562module_exit(tbf_module_exit)
563MODULE_LICENSE("GPL");