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