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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#include <linux/module.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include <linux/types.h>
17#include <linux/kernel.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <linux/string.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <linux/errno.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/skbuff.h>
Patrick McHardy0ba48052007-07-02 22:49:07 -070021#include <net/netlink.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <net/pkt_sched.h>
23
24
25/* Simple Token Bucket Filter.
26 =======================================
27
28 SOURCE.
29 -------
30
31 None.
32
33 Description.
34 ------------
35
36 A data flow obeys TBF with rate R and depth B, if for any
37 time interval t_i...t_f the number of transmitted bits
38 does not exceed B + R*(t_f-t_i).
39
40 Packetized version of this definition:
41 The sequence of packets of sizes s_i served at moments t_i
42 obeys TBF, if for any i<=k:
43
44 s_i+....+s_k <= B + R*(t_k - t_i)
45
46 Algorithm.
47 ----------
48
49 Let N(t_i) be B/R initially and N(t) grow continuously with time as:
50
51 N(t+delta) = min{B/R, N(t) + delta}
52
53 If the first packet in queue has length S, it may be
54 transmitted only at the time t_* when S/R <= N(t_*),
55 and in this case N(t) jumps:
56
57 N(t_* + 0) = N(t_* - 0) - S/R.
58
59
60
61 Actually, QoS requires two TBF to be applied to a data stream.
62 One of them controls steady state burst size, another
63 one with rate P (peak rate) and depth M (equal to link MTU)
64 limits bursts at a smaller time scale.
65
66 It is easy to see that P>R, and B>M. If P is infinity, this double
67 TBF is equivalent to a single one.
68
69 When TBF works in reshaping mode, latency is estimated as:
70
71 lat = max ((L-B)/R, (L-M)/P)
72
73
74 NOTES.
75 ------
76
77 If TBF throttles, it starts a watchdog timer, which will wake it up
78 when it is ready to transmit.
79 Note that the minimal timer resolution is 1/HZ.
80 If no new packets arrive during this period,
81 or if the device is not awaken by EOI for some previous packet,
82 TBF can stop its activity for 1/HZ.
83
84
85 This means, that with depth B, the maximal rate is
86
87 R_crit = B*HZ
88
89 F.e. for 10Mbit ethernet and HZ=100 the minimal allowed B is ~10Kbytes.
90
91 Note that the peak rate TBF is much more tough: with MTU 1500
92 P_crit = 150Kbytes/sec. So, if you need greater peak
93 rates, use alpha with HZ=1000 :-)
94
95 With classful TBF, limit is just kept for backwards compatibility.
96 It is passed to the default bfifo qdisc - if the inner qdisc is
97 changed the limit is not effective anymore.
98*/
99
100struct tbf_sched_data
101{
102/* Parameters */
103 u32 limit; /* Maximal length of backlog: bytes */
104 u32 buffer; /* Token bucket depth/rate: MUST BE >= MTU/B */
105 u32 mtu;
106 u32 max_size;
107 struct qdisc_rate_table *R_tab;
108 struct qdisc_rate_table *P_tab;
109
110/* Variables */
111 long tokens; /* Current number of B tokens */
112 long ptokens; /* Current number of P tokens */
113 psched_time_t t_c; /* Time check-point */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 struct Qdisc *qdisc; /* Inner qdisc, default - bfifo queue */
Patrick McHardyf7f593e2007-03-16 01:20:07 -0700115 struct qdisc_watchdog watchdog; /* Watchdog timer */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116};
117
Jesper Dangaard Brouere9bef552007-09-12 16:35:24 +0200118#define L2T(q,L) qdisc_l2t((q)->R_tab,L)
119#define L2T_P(q,L) qdisc_l2t((q)->P_tab,L)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120
121static int tbf_enqueue(struct sk_buff *skb, struct Qdisc* sch)
122{
123 struct tbf_sched_data *q = qdisc_priv(sch);
124 int ret;
125
126 if (skb->len > q->max_size) {
127 sch->qstats.drops++;
Patrick McHardyc3bc7cf2007-07-15 00:03:05 -0700128#ifdef CONFIG_NET_CLS_ACT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 if (sch->reshape_fail == NULL || sch->reshape_fail(skb, sch))
130#endif
131 kfree_skb(skb);
132
133 return NET_XMIT_DROP;
134 }
135
136 if ((ret = q->qdisc->enqueue(skb, q->qdisc)) != 0) {
137 sch->qstats.drops++;
138 return ret;
139 }
140
141 sch->q.qlen++;
142 sch->bstats.bytes += skb->len;
143 sch->bstats.packets++;
144 return 0;
145}
146
147static int tbf_requeue(struct sk_buff *skb, struct Qdisc* sch)
148{
149 struct tbf_sched_data *q = qdisc_priv(sch);
150 int ret;
151
152 if ((ret = q->qdisc->ops->requeue(skb, q->qdisc)) == 0) {
153 sch->q.qlen++;
154 sch->qstats.requeues++;
155 }
156
157 return ret;
158}
159
160static unsigned int tbf_drop(struct Qdisc* sch)
161{
162 struct tbf_sched_data *q = qdisc_priv(sch);
Patrick McHardy6d037a22006-03-20 19:00:49 -0800163 unsigned int len = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164
Patrick McHardy6d037a22006-03-20 19:00:49 -0800165 if (q->qdisc->ops->drop && (len = q->qdisc->ops->drop(q->qdisc)) != 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 sch->q.qlen--;
167 sch->qstats.drops++;
168 }
169 return len;
170}
171
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172static struct sk_buff *tbf_dequeue(struct Qdisc* sch)
173{
174 struct tbf_sched_data *q = qdisc_priv(sch);
175 struct sk_buff *skb;
176
177 skb = q->qdisc->dequeue(q->qdisc);
178
179 if (skb) {
180 psched_time_t now;
Patrick McHardyf7f593e2007-03-16 01:20:07 -0700181 long toks;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 long ptoks = 0;
183 unsigned int len = skb->len;
184
Patrick McHardy3bebcda2007-03-23 11:29:25 -0700185 now = psched_get_time();
Patrick McHardy03cc45c2007-03-23 11:29:11 -0700186 toks = psched_tdiff_bounded(now, q->t_c, q->buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187
188 if (q->P_tab) {
189 ptoks = toks + q->ptokens;
190 if (ptoks > (long)q->mtu)
191 ptoks = q->mtu;
192 ptoks -= L2T_P(q, len);
193 }
194 toks += q->tokens;
195 if (toks > (long)q->buffer)
196 toks = q->buffer;
197 toks -= L2T(q, len);
198
199 if ((toks|ptoks) >= 0) {
200 q->t_c = now;
201 q->tokens = toks;
202 q->ptokens = ptoks;
203 sch->q.qlen--;
204 sch->flags &= ~TCQ_F_THROTTLED;
205 return skb;
206 }
207
Patrick McHardyf7f593e2007-03-16 01:20:07 -0700208 qdisc_watchdog_schedule(&q->watchdog,
209 now + max_t(long, -toks, -ptoks));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210
211 /* Maybe we have a shorter packet in the queue,
212 which can be sent now. It sounds cool,
213 but, however, this is wrong in principle.
214 We MUST NOT reorder packets under these circumstances.
215
216 Really, if we split the flow into independent
217 subflows, it would be a very good solution.
218 This is the main idea of all FQ algorithms
219 (cf. CSZ, HPFQ, HFSC)
220 */
221
222 if (q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS) {
223 /* When requeue fails skb is dropped */
Patrick McHardye488eaf2006-11-29 17:37:42 -0800224 qdisc_tree_decrease_qlen(q->qdisc, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225 sch->qstats.drops++;
226 }
227
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228 sch->qstats.overlimits++;
229 }
230 return NULL;
231}
232
233static void tbf_reset(struct Qdisc* sch)
234{
235 struct tbf_sched_data *q = qdisc_priv(sch);
236
237 qdisc_reset(q->qdisc);
238 sch->q.qlen = 0;
Patrick McHardy3bebcda2007-03-23 11:29:25 -0700239 q->t_c = psched_get_time();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 q->tokens = q->buffer;
241 q->ptokens = q->mtu;
Patrick McHardyf7f593e2007-03-16 01:20:07 -0700242 qdisc_watchdog_cancel(&q->watchdog);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243}
244
Patrick McHardy9f9afec2006-11-29 17:35:18 -0800245static struct Qdisc *tbf_create_dflt_qdisc(struct Qdisc *sch, u32 limit)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246{
Patrick McHardy9f9afec2006-11-29 17:35:18 -0800247 struct Qdisc *q;
YOSHIFUJI Hideaki10297b92007-02-09 23:25:16 +0900248 struct rtattr *rta;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 int ret;
250
Patrick McHardy9f9afec2006-11-29 17:35:18 -0800251 q = qdisc_create_dflt(sch->dev, &bfifo_qdisc_ops,
252 TC_H_MAKE(sch->handle, 1));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253 if (q) {
254 rta = kmalloc(RTA_LENGTH(sizeof(struct tc_fifo_qopt)), GFP_KERNEL);
255 if (rta) {
256 rta->rta_type = RTM_NEWQDISC;
YOSHIFUJI Hideaki10297b92007-02-09 23:25:16 +0900257 rta->rta_len = RTA_LENGTH(sizeof(struct tc_fifo_qopt));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 ((struct tc_fifo_qopt *)RTA_DATA(rta))->limit = limit;
259
260 ret = q->ops->change(q, rta);
261 kfree(rta);
262
263 if (ret == 0)
264 return q;
265 }
266 qdisc_destroy(q);
267 }
268
269 return NULL;
270}
271
272static int tbf_change(struct Qdisc* sch, struct rtattr *opt)
273{
274 int err = -EINVAL;
275 struct tbf_sched_data *q = qdisc_priv(sch);
276 struct rtattr *tb[TCA_TBF_PTAB];
277 struct tc_tbf_qopt *qopt;
278 struct qdisc_rate_table *rtab = NULL;
279 struct qdisc_rate_table *ptab = NULL;
280 struct Qdisc *child = NULL;
281 int max_size,n;
282
283 if (rtattr_parse_nested(tb, TCA_TBF_PTAB, opt) ||
284 tb[TCA_TBF_PARMS-1] == NULL ||
285 RTA_PAYLOAD(tb[TCA_TBF_PARMS-1]) < sizeof(*qopt))
286 goto done;
287
288 qopt = RTA_DATA(tb[TCA_TBF_PARMS-1]);
289 rtab = qdisc_get_rtab(&qopt->rate, tb[TCA_TBF_RTAB-1]);
290 if (rtab == NULL)
291 goto done;
292
293 if (qopt->peakrate.rate) {
294 if (qopt->peakrate.rate > qopt->rate.rate)
295 ptab = qdisc_get_rtab(&qopt->peakrate, tb[TCA_TBF_PTAB-1]);
296 if (ptab == NULL)
297 goto done;
298 }
299
300 for (n = 0; n < 256; n++)
301 if (rtab->data[n] > qopt->buffer) break;
302 max_size = (n << qopt->rate.cell_log)-1;
303 if (ptab) {
304 int size;
305
306 for (n = 0; n < 256; n++)
307 if (ptab->data[n] > qopt->mtu) break;
308 size = (n << qopt->peakrate.cell_log)-1;
309 if (size < max_size) max_size = size;
310 }
311 if (max_size < 0)
312 goto done;
313
Patrick McHardy053cfed2006-03-20 19:01:21 -0800314 if (qopt->limit > 0) {
Patrick McHardy9f9afec2006-11-29 17:35:18 -0800315 if ((child = tbf_create_dflt_qdisc(sch, qopt->limit)) == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316 goto done;
317 }
318
319 sch_tree_lock(sch);
Patrick McHardy5e50da02006-11-29 17:36:20 -0800320 if (child) {
321 qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen);
Patrick McHardy053cfed2006-03-20 19:01:21 -0800322 qdisc_destroy(xchg(&q->qdisc, child));
Patrick McHardy5e50da02006-11-29 17:36:20 -0800323 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 q->limit = qopt->limit;
325 q->mtu = qopt->mtu;
326 q->max_size = max_size;
327 q->buffer = qopt->buffer;
328 q->tokens = q->buffer;
329 q->ptokens = q->mtu;
330 rtab = xchg(&q->R_tab, rtab);
331 ptab = xchg(&q->P_tab, ptab);
332 sch_tree_unlock(sch);
333 err = 0;
334done:
335 if (rtab)
336 qdisc_put_rtab(rtab);
337 if (ptab)
338 qdisc_put_rtab(ptab);
339 return err;
340}
341
342static int tbf_init(struct Qdisc* sch, struct rtattr *opt)
343{
344 struct tbf_sched_data *q = qdisc_priv(sch);
345
346 if (opt == NULL)
347 return -EINVAL;
348
Patrick McHardy3bebcda2007-03-23 11:29:25 -0700349 q->t_c = psched_get_time();
Patrick McHardyf7f593e2007-03-16 01:20:07 -0700350 qdisc_watchdog_init(&q->watchdog, sch);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 q->qdisc = &noop_qdisc;
352
353 return tbf_change(sch, opt);
354}
355
356static void tbf_destroy(struct Qdisc *sch)
357{
358 struct tbf_sched_data *q = qdisc_priv(sch);
359
Patrick McHardyf7f593e2007-03-16 01:20:07 -0700360 qdisc_watchdog_cancel(&q->watchdog);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361
362 if (q->P_tab)
363 qdisc_put_rtab(q->P_tab);
364 if (q->R_tab)
365 qdisc_put_rtab(q->R_tab);
366
367 qdisc_destroy(q->qdisc);
368}
369
370static int tbf_dump(struct Qdisc *sch, struct sk_buff *skb)
371{
372 struct tbf_sched_data *q = qdisc_priv(sch);
Arnaldo Carvalho de Melo27a884d2007-04-19 20:29:13 -0700373 unsigned char *b = skb_tail_pointer(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 struct rtattr *rta;
375 struct tc_tbf_qopt opt;
376
377 rta = (struct rtattr*)b;
378 RTA_PUT(skb, TCA_OPTIONS, 0, NULL);
379
380 opt.limit = q->limit;
381 opt.rate = q->R_tab->rate;
382 if (q->P_tab)
383 opt.peakrate = q->P_tab->rate;
384 else
385 memset(&opt.peakrate, 0, sizeof(opt.peakrate));
386 opt.mtu = q->mtu;
387 opt.buffer = q->buffer;
388 RTA_PUT(skb, TCA_TBF_PARMS, sizeof(opt), &opt);
Arnaldo Carvalho de Melo27a884d2007-04-19 20:29:13 -0700389 rta->rta_len = skb_tail_pointer(skb) - b;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390
391 return skb->len;
392
393rtattr_failure:
Arnaldo Carvalho de Melodc5fc572007-03-25 23:06:12 -0700394 nlmsg_trim(skb, b);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395 return -1;
396}
397
398static int tbf_dump_class(struct Qdisc *sch, unsigned long cl,
399 struct sk_buff *skb, struct tcmsg *tcm)
400{
401 struct tbf_sched_data *q = qdisc_priv(sch);
402
403 if (cl != 1) /* only one class */
404 return -ENOENT;
405
406 tcm->tcm_handle |= TC_H_MIN(1);
407 tcm->tcm_info = q->qdisc->handle;
408
409 return 0;
410}
411
412static int tbf_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
413 struct Qdisc **old)
414{
415 struct tbf_sched_data *q = qdisc_priv(sch);
416
417 if (new == NULL)
418 new = &noop_qdisc;
419
420 sch_tree_lock(sch);
421 *old = xchg(&q->qdisc, new);
Patrick McHardy5e50da02006-11-29 17:36:20 -0800422 qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 qdisc_reset(*old);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 sch_tree_unlock(sch);
425
426 return 0;
427}
428
429static struct Qdisc *tbf_leaf(struct Qdisc *sch, unsigned long arg)
430{
431 struct tbf_sched_data *q = qdisc_priv(sch);
432 return q->qdisc;
433}
434
435static unsigned long tbf_get(struct Qdisc *sch, u32 classid)
436{
437 return 1;
438}
439
440static void tbf_put(struct Qdisc *sch, unsigned long arg)
441{
442}
443
YOSHIFUJI Hideaki10297b92007-02-09 23:25:16 +0900444static int tbf_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445 struct rtattr **tca, unsigned long *arg)
446{
447 return -ENOSYS;
448}
449
450static int tbf_delete(struct Qdisc *sch, unsigned long arg)
451{
452 return -ENOSYS;
453}
454
455static void tbf_walk(struct Qdisc *sch, struct qdisc_walker *walker)
456{
457 if (!walker->stop) {
458 if (walker->count >= walker->skip)
459 if (walker->fn(sch, 1, walker) < 0) {
460 walker->stop = 1;
461 return;
462 }
463 walker->count++;
464 }
465}
466
467static struct tcf_proto **tbf_find_tcf(struct Qdisc *sch, unsigned long cl)
468{
469 return NULL;
470}
471
472static struct Qdisc_class_ops tbf_class_ops =
473{
474 .graft = tbf_graft,
475 .leaf = tbf_leaf,
476 .get = tbf_get,
477 .put = tbf_put,
478 .change = tbf_change_class,
479 .delete = tbf_delete,
480 .walk = tbf_walk,
481 .tcf_chain = tbf_find_tcf,
482 .dump = tbf_dump_class,
483};
484
485static struct Qdisc_ops tbf_qdisc_ops = {
486 .next = NULL,
487 .cl_ops = &tbf_class_ops,
488 .id = "tbf",
489 .priv_size = sizeof(struct tbf_sched_data),
490 .enqueue = tbf_enqueue,
491 .dequeue = tbf_dequeue,
492 .requeue = tbf_requeue,
493 .drop = tbf_drop,
494 .init = tbf_init,
495 .reset = tbf_reset,
496 .destroy = tbf_destroy,
497 .change = tbf_change,
498 .dump = tbf_dump,
499 .owner = THIS_MODULE,
500};
501
502static int __init tbf_module_init(void)
503{
504 return register_qdisc(&tbf_qdisc_ops);
505}
506
507static void __exit tbf_module_exit(void)
508{
509 unregister_qdisc(&tbf_qdisc_ops);
510}
511module_init(tbf_module_init)
512module_exit(tbf_module_exit)
513MODULE_LICENSE("GPL");