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