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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * net/sched/sch_cbs.c Credit Based Shaper
4 *
5 * Authors: Vinicius Costa Gomes <vinicius.gomes@intel.com>
6 */
7
8/* Credit Based Shaper (CBS)
9 * =========================
10 *
11 * This is a simple rate-limiting shaper aimed at TSN applications on
12 * systems with known traffic workloads.
13 *
14 * Its algorithm is defined by the IEEE 802.1Q-2014 Specification,
15 * Section 8.6.8.2, and explained in more detail in the Annex L of the
16 * same specification.
17 *
18 * There are four tunables to be considered:
19 *
20 * 'idleslope': Idleslope is the rate of credits that is
21 * accumulated (in kilobits per second) when there is at least
22 * one packet waiting for transmission. Packets are transmitted
23 * when the current value of credits is equal or greater than
24 * zero. When there is no packet to be transmitted the amount of
25 * credits is set to zero. This is the main tunable of the CBS
26 * algorithm.
27 *
28 * 'sendslope':
29 * Sendslope is the rate of credits that is depleted (it should be a
30 * negative number of kilobits per second) when a transmission is
31 * ocurring. It can be calculated as follows, (IEEE 802.1Q-2014 Section
32 * 8.6.8.2 item g):
33 *
34 * sendslope = idleslope - port_transmit_rate
35 *
36 * 'hicredit': Hicredit defines the maximum amount of credits (in
37 * bytes) that can be accumulated. Hicredit depends on the
38 * characteristics of interfering traffic,
39 * 'max_interference_size' is the maximum size of any burst of
40 * traffic that can delay the transmission of a frame that is
41 * available for transmission for this traffic class, (IEEE
42 * 802.1Q-2014 Annex L, Equation L-3):
43 *
44 * hicredit = max_interference_size * (idleslope / port_transmit_rate)
45 *
46 * 'locredit': Locredit is the minimum amount of credits that can
47 * be reached. It is a function of the traffic flowing through
48 * this qdisc (IEEE 802.1Q-2014 Annex L, Equation L-2):
49 *
50 * locredit = max_frame_size * (sendslope / port_transmit_rate)
51 */
52
53#include <linux/module.h>
54#include <linux/types.h>
55#include <linux/kernel.h>
56#include <linux/string.h>
57#include <linux/errno.h>
58#include <linux/skbuff.h>
59#include <net/netevent.h>
60#include <net/netlink.h>
61#include <net/sch_generic.h>
62#include <net/pkt_sched.h>
63
64static LIST_HEAD(cbs_list);
65static DEFINE_SPINLOCK(cbs_list_lock);
66
67#define BYTES_PER_KBIT (1000LL / 8)
68
69struct cbs_sched_data {
70 bool offload;
71 int queue;
72 atomic64_t port_rate; /* in bytes/s */
73 s64 last; /* timestamp in ns */
74 s64 credits; /* in bytes */
75 s32 locredit; /* in bytes */
76 s32 hicredit; /* in bytes */
77 s64 sendslope; /* in bytes/s */
78 s64 idleslope; /* in bytes/s */
79 struct qdisc_watchdog watchdog;
80 int (*enqueue)(struct sk_buff *skb, struct Qdisc *sch,
81 struct sk_buff **to_free);
82 struct sk_buff *(*dequeue)(struct Qdisc *sch);
83 struct Qdisc *qdisc;
84 struct list_head cbs_list;
85};
86
87static int cbs_child_enqueue(struct sk_buff *skb, struct Qdisc *sch,
88 struct Qdisc *child,
89 struct sk_buff **to_free)
90{
91 unsigned int len = qdisc_pkt_len(skb);
92 int err;
93
94 err = child->ops->enqueue(skb, child, to_free);
95 if (err != NET_XMIT_SUCCESS)
96 return err;
97
98 sch->qstats.backlog += len;
99 sch->q.qlen++;
100
101 return NET_XMIT_SUCCESS;
102}
103
104static int cbs_enqueue_offload(struct sk_buff *skb, struct Qdisc *sch,
105 struct sk_buff **to_free)
106{
107 struct cbs_sched_data *q = qdisc_priv(sch);
108 struct Qdisc *qdisc = q->qdisc;
109
110 return cbs_child_enqueue(skb, sch, qdisc, to_free);
111}
112
113static int cbs_enqueue_soft(struct sk_buff *skb, struct Qdisc *sch,
114 struct sk_buff **to_free)
115{
116 struct cbs_sched_data *q = qdisc_priv(sch);
117 struct Qdisc *qdisc = q->qdisc;
118
119 if (sch->q.qlen == 0 && q->credits > 0) {
120 /* We need to stop accumulating credits when there's
121 * no enqueued packets and q->credits is positive.
122 */
123 q->credits = 0;
124 q->last = ktime_get_ns();
125 }
126
127 return cbs_child_enqueue(skb, sch, qdisc, to_free);
128}
129
130static int cbs_enqueue(struct sk_buff *skb, struct Qdisc *sch,
131 struct sk_buff **to_free)
132{
133 struct cbs_sched_data *q = qdisc_priv(sch);
134
135 return q->enqueue(skb, sch, to_free);
136}
137
138/* timediff is in ns, slope is in bytes/s */
139static s64 timediff_to_credits(s64 timediff, s64 slope)
140{
141 return div64_s64(timediff * slope, NSEC_PER_SEC);
142}
143
144static s64 delay_from_credits(s64 credits, s64 slope)
145{
146 if (unlikely(slope == 0))
147 return S64_MAX;
148
149 return div64_s64(-credits * NSEC_PER_SEC, slope);
150}
151
152static s64 credits_from_len(unsigned int len, s64 slope, s64 port_rate)
153{
154 if (unlikely(port_rate == 0))
155 return S64_MAX;
156
157 return div64_s64(len * slope, port_rate);
158}
159
160static struct sk_buff *cbs_child_dequeue(struct Qdisc *sch, struct Qdisc *child)
161{
162 struct sk_buff *skb;
163
164 skb = child->ops->dequeue(child);
165 if (!skb)
166 return NULL;
167
168 qdisc_qstats_backlog_dec(sch, skb);
169 qdisc_bstats_update(sch, skb);
170 sch->q.qlen--;
171
172 return skb;
173}
174
175static struct sk_buff *cbs_dequeue_soft(struct Qdisc *sch)
176{
177 struct cbs_sched_data *q = qdisc_priv(sch);
178 struct Qdisc *qdisc = q->qdisc;
179 s64 now = ktime_get_ns();
180 struct sk_buff *skb;
181 s64 credits;
182 int len;
183
184 if (q->credits < 0) {
185 credits = timediff_to_credits(now - q->last, q->idleslope);
186
187 credits = q->credits + credits;
188 q->credits = min_t(s64, credits, q->hicredit);
189
190 if (q->credits < 0) {
191 s64 delay;
192
193 delay = delay_from_credits(q->credits, q->idleslope);
194 qdisc_watchdog_schedule_ns(&q->watchdog, now + delay);
195
196 q->last = now;
197
198 return NULL;
199 }
200 }
201 skb = cbs_child_dequeue(sch, qdisc);
202 if (!skb)
203 return NULL;
204
205 len = qdisc_pkt_len(skb);
206
207 /* As sendslope is a negative number, this will decrease the
208 * amount of q->credits.
209 */
210 credits = credits_from_len(len, q->sendslope,
211 atomic64_read(&q->port_rate));
212 credits += q->credits;
213
214 q->credits = max_t(s64, credits, q->locredit);
215 q->last = now;
216
217 return skb;
218}
219
220static struct sk_buff *cbs_dequeue_offload(struct Qdisc *sch)
221{
222 struct cbs_sched_data *q = qdisc_priv(sch);
223 struct Qdisc *qdisc = q->qdisc;
224
225 return cbs_child_dequeue(sch, qdisc);
226}
227
228static struct sk_buff *cbs_dequeue(struct Qdisc *sch)
229{
230 struct cbs_sched_data *q = qdisc_priv(sch);
231
232 return q->dequeue(sch);
233}
234
235static const struct nla_policy cbs_policy[TCA_CBS_MAX + 1] = {
236 [TCA_CBS_PARMS] = { .len = sizeof(struct tc_cbs_qopt) },
237};
238
239static void cbs_disable_offload(struct net_device *dev,
240 struct cbs_sched_data *q)
241{
242 struct tc_cbs_qopt_offload cbs = { };
243 const struct net_device_ops *ops;
244 int err;
245
246 if (!q->offload)
247 return;
248
249 q->enqueue = cbs_enqueue_soft;
250 q->dequeue = cbs_dequeue_soft;
251
252 ops = dev->netdev_ops;
253 if (!ops->ndo_setup_tc)
254 return;
255
256 cbs.queue = q->queue;
257 cbs.enable = 0;
258
259 err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_CBS, &cbs);
260 if (err < 0)
261 pr_warn("Couldn't disable CBS offload for queue %d\n",
262 cbs.queue);
263}
264
265static int cbs_enable_offload(struct net_device *dev, struct cbs_sched_data *q,
266 const struct tc_cbs_qopt *opt,
267 struct netlink_ext_ack *extack)
268{
269 const struct net_device_ops *ops = dev->netdev_ops;
270 struct tc_cbs_qopt_offload cbs = { };
271 int err;
272
273 if (!ops->ndo_setup_tc) {
274 NL_SET_ERR_MSG(extack, "Specified device does not support cbs offload");
275 return -EOPNOTSUPP;
276 }
277
278 cbs.queue = q->queue;
279
280 cbs.enable = 1;
281 cbs.hicredit = opt->hicredit;
282 cbs.locredit = opt->locredit;
283 cbs.idleslope = opt->idleslope;
284 cbs.sendslope = opt->sendslope;
285
286 err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_CBS, &cbs);
287 if (err < 0) {
288 NL_SET_ERR_MSG(extack, "Specified device failed to setup cbs hardware offload");
289 return err;
290 }
291
292 q->enqueue = cbs_enqueue_offload;
293 q->dequeue = cbs_dequeue_offload;
294
295 return 0;
296}
297
298static void cbs_set_port_rate(struct net_device *dev, struct cbs_sched_data *q)
299{
300 struct ethtool_link_ksettings ecmd;
301 int speed = SPEED_10;
302 int port_rate;
303 int err;
304
305 err = __ethtool_get_link_ksettings(dev, &ecmd);
306 if (err < 0)
307 goto skip;
308
309 if (ecmd.base.speed && ecmd.base.speed != SPEED_UNKNOWN)
310 speed = ecmd.base.speed;
311
312skip:
313 port_rate = speed * 1000 * BYTES_PER_KBIT;
314
315 atomic64_set(&q->port_rate, port_rate);
316 netdev_dbg(dev, "cbs: set %s's port_rate to: %lld, linkspeed: %d\n",
317 dev->name, (long long)atomic64_read(&q->port_rate),
318 ecmd.base.speed);
319}
320
321static int cbs_dev_notifier(struct notifier_block *nb, unsigned long event,
322 void *ptr)
323{
324 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
325 struct cbs_sched_data *q;
326 struct net_device *qdev;
327 bool found = false;
328
329 ASSERT_RTNL();
330
331 if (event != NETDEV_UP && event != NETDEV_CHANGE)
332 return NOTIFY_DONE;
333
334 spin_lock(&cbs_list_lock);
335 list_for_each_entry(q, &cbs_list, cbs_list) {
336 qdev = qdisc_dev(q->qdisc);
337 if (qdev == dev) {
338 found = true;
339 break;
340 }
341 }
342 spin_unlock(&cbs_list_lock);
343
344 if (found)
345 cbs_set_port_rate(dev, q);
346
347 return NOTIFY_DONE;
348}
349
350static int cbs_change(struct Qdisc *sch, struct nlattr *opt,
351 struct netlink_ext_ack *extack)
352{
353 struct cbs_sched_data *q = qdisc_priv(sch);
354 struct net_device *dev = qdisc_dev(sch);
355 struct nlattr *tb[TCA_CBS_MAX + 1];
356 struct tc_cbs_qopt *qopt;
357 int err;
358
359 err = nla_parse_nested_deprecated(tb, TCA_CBS_MAX, opt, cbs_policy,
360 extack);
361 if (err < 0)
362 return err;
363
364 if (!tb[TCA_CBS_PARMS]) {
365 NL_SET_ERR_MSG(extack, "Missing CBS parameter which are mandatory");
366 return -EINVAL;
367 }
368
369 qopt = nla_data(tb[TCA_CBS_PARMS]);
370
371 if (!qopt->offload) {
372 cbs_set_port_rate(dev, q);
373 cbs_disable_offload(dev, q);
374 } else {
375 err = cbs_enable_offload(dev, q, qopt, extack);
376 if (err < 0)
377 return err;
378 }
379
380 /* Everything went OK, save the parameters used. */
381 q->hicredit = qopt->hicredit;
382 q->locredit = qopt->locredit;
383 q->idleslope = qopt->idleslope * BYTES_PER_KBIT;
384 q->sendslope = qopt->sendslope * BYTES_PER_KBIT;
385 q->offload = qopt->offload;
386
387 return 0;
388}
389
390static int cbs_init(struct Qdisc *sch, struct nlattr *opt,
391 struct netlink_ext_ack *extack)
392{
393 struct cbs_sched_data *q = qdisc_priv(sch);
394 struct net_device *dev = qdisc_dev(sch);
395
396 if (!opt) {
397 NL_SET_ERR_MSG(extack, "Missing CBS qdisc options which are mandatory");
398 return -EINVAL;
399 }
400
401 q->qdisc = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
402 sch->handle, extack);
403 if (!q->qdisc)
404 return -ENOMEM;
405
406 spin_lock(&cbs_list_lock);
407 list_add(&q->cbs_list, &cbs_list);
408 spin_unlock(&cbs_list_lock);
409
410 qdisc_hash_add(q->qdisc, false);
411
412 q->queue = sch->dev_queue - netdev_get_tx_queue(dev, 0);
413
414 q->enqueue = cbs_enqueue_soft;
415 q->dequeue = cbs_dequeue_soft;
416
417 qdisc_watchdog_init(&q->watchdog, sch);
418
419 return cbs_change(sch, opt, extack);
420}
421
422static void cbs_destroy(struct Qdisc *sch)
423{
424 struct cbs_sched_data *q = qdisc_priv(sch);
425 struct net_device *dev = qdisc_dev(sch);
426
427 /* Nothing to do if we couldn't create the underlying qdisc */
428 if (!q->qdisc)
429 return;
430
431 qdisc_watchdog_cancel(&q->watchdog);
432 cbs_disable_offload(dev, q);
433
434 spin_lock(&cbs_list_lock);
435 list_del(&q->cbs_list);
436 spin_unlock(&cbs_list_lock);
437
438 qdisc_put(q->qdisc);
439}
440
441static int cbs_dump(struct Qdisc *sch, struct sk_buff *skb)
442{
443 struct cbs_sched_data *q = qdisc_priv(sch);
444 struct tc_cbs_qopt opt = { };
445 struct nlattr *nest;
446
447 nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
448 if (!nest)
449 goto nla_put_failure;
450
451 opt.hicredit = q->hicredit;
452 opt.locredit = q->locredit;
453 opt.sendslope = div64_s64(q->sendslope, BYTES_PER_KBIT);
454 opt.idleslope = div64_s64(q->idleslope, BYTES_PER_KBIT);
455 opt.offload = q->offload;
456
457 if (nla_put(skb, TCA_CBS_PARMS, sizeof(opt), &opt))
458 goto nla_put_failure;
459
460 return nla_nest_end(skb, nest);
461
462nla_put_failure:
463 nla_nest_cancel(skb, nest);
464 return -1;
465}
466
467static int cbs_dump_class(struct Qdisc *sch, unsigned long cl,
468 struct sk_buff *skb, struct tcmsg *tcm)
469{
470 struct cbs_sched_data *q = qdisc_priv(sch);
471
472 if (cl != 1 || !q->qdisc) /* only one class */
473 return -ENOENT;
474
475 tcm->tcm_handle |= TC_H_MIN(1);
476 tcm->tcm_info = q->qdisc->handle;
477
478 return 0;
479}
480
481static int cbs_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
482 struct Qdisc **old, struct netlink_ext_ack *extack)
483{
484 struct cbs_sched_data *q = qdisc_priv(sch);
485
486 if (!new) {
487 new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
488 sch->handle, NULL);
489 if (!new)
490 new = &noop_qdisc;
491 }
492
493 *old = qdisc_replace(sch, new, &q->qdisc);
494 return 0;
495}
496
497static struct Qdisc *cbs_leaf(struct Qdisc *sch, unsigned long arg)
498{
499 struct cbs_sched_data *q = qdisc_priv(sch);
500
501 return q->qdisc;
502}
503
504static unsigned long cbs_find(struct Qdisc *sch, u32 classid)
505{
506 return 1;
507}
508
509static void cbs_walk(struct Qdisc *sch, struct qdisc_walker *walker)
510{
511 if (!walker->stop) {
512 if (walker->count >= walker->skip) {
513 if (walker->fn(sch, 1, walker) < 0) {
514 walker->stop = 1;
515 return;
516 }
517 }
518 walker->count++;
519 }
520}
521
522static const struct Qdisc_class_ops cbs_class_ops = {
523 .graft = cbs_graft,
524 .leaf = cbs_leaf,
525 .find = cbs_find,
526 .walk = cbs_walk,
527 .dump = cbs_dump_class,
528};
529
530static struct Qdisc_ops cbs_qdisc_ops __read_mostly = {
531 .id = "cbs",
532 .cl_ops = &cbs_class_ops,
533 .priv_size = sizeof(struct cbs_sched_data),
534 .enqueue = cbs_enqueue,
535 .dequeue = cbs_dequeue,
536 .peek = qdisc_peek_dequeued,
537 .init = cbs_init,
538 .reset = qdisc_reset_queue,
539 .destroy = cbs_destroy,
540 .change = cbs_change,
541 .dump = cbs_dump,
542 .owner = THIS_MODULE,
543};
544
545static struct notifier_block cbs_device_notifier = {
546 .notifier_call = cbs_dev_notifier,
547};
548
549static int __init cbs_module_init(void)
550{
551 int err;
552
553 err = register_netdevice_notifier(&cbs_device_notifier);
554 if (err)
555 return err;
556
557 err = register_qdisc(&cbs_qdisc_ops);
558 if (err)
559 unregister_netdevice_notifier(&cbs_device_notifier);
560
561 return err;
562}
563
564static void __exit cbs_module_exit(void)
565{
566 unregister_qdisc(&cbs_qdisc_ops);
567 unregister_netdevice_notifier(&cbs_device_notifier);
568}
569module_init(cbs_module_init)
570module_exit(cbs_module_exit)
571MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * net/sched/sch_cbs.c Credit Based Shaper
4 *
5 * Authors: Vinicius Costa Gomes <vinicius.gomes@intel.com>
6 */
7
8/* Credit Based Shaper (CBS)
9 * =========================
10 *
11 * This is a simple rate-limiting shaper aimed at TSN applications on
12 * systems with known traffic workloads.
13 *
14 * Its algorithm is defined by the IEEE 802.1Q-2014 Specification,
15 * Section 8.6.8.2, and explained in more detail in the Annex L of the
16 * same specification.
17 *
18 * There are four tunables to be considered:
19 *
20 * 'idleslope': Idleslope is the rate of credits that is
21 * accumulated (in kilobits per second) when there is at least
22 * one packet waiting for transmission. Packets are transmitted
23 * when the current value of credits is equal or greater than
24 * zero. When there is no packet to be transmitted the amount of
25 * credits is set to zero. This is the main tunable of the CBS
26 * algorithm.
27 *
28 * 'sendslope':
29 * Sendslope is the rate of credits that is depleted (it should be a
30 * negative number of kilobits per second) when a transmission is
31 * ocurring. It can be calculated as follows, (IEEE 802.1Q-2014 Section
32 * 8.6.8.2 item g):
33 *
34 * sendslope = idleslope - port_transmit_rate
35 *
36 * 'hicredit': Hicredit defines the maximum amount of credits (in
37 * bytes) that can be accumulated. Hicredit depends on the
38 * characteristics of interfering traffic,
39 * 'max_interference_size' is the maximum size of any burst of
40 * traffic that can delay the transmission of a frame that is
41 * available for transmission for this traffic class, (IEEE
42 * 802.1Q-2014 Annex L, Equation L-3):
43 *
44 * hicredit = max_interference_size * (idleslope / port_transmit_rate)
45 *
46 * 'locredit': Locredit is the minimum amount of credits that can
47 * be reached. It is a function of the traffic flowing through
48 * this qdisc (IEEE 802.1Q-2014 Annex L, Equation L-2):
49 *
50 * locredit = max_frame_size * (sendslope / port_transmit_rate)
51 */
52
53#include <linux/ethtool.h>
54#include <linux/module.h>
55#include <linux/types.h>
56#include <linux/kernel.h>
57#include <linux/string.h>
58#include <linux/errno.h>
59#include <linux/skbuff.h>
60#include <net/netevent.h>
61#include <net/netlink.h>
62#include <net/sch_generic.h>
63#include <net/pkt_sched.h>
64
65static LIST_HEAD(cbs_list);
66static DEFINE_SPINLOCK(cbs_list_lock);
67
68#define BYTES_PER_KBIT (1000LL / 8)
69
70struct cbs_sched_data {
71 bool offload;
72 int queue;
73 atomic64_t port_rate; /* in bytes/s */
74 s64 last; /* timestamp in ns */
75 s64 credits; /* in bytes */
76 s32 locredit; /* in bytes */
77 s32 hicredit; /* in bytes */
78 s64 sendslope; /* in bytes/s */
79 s64 idleslope; /* in bytes/s */
80 struct qdisc_watchdog watchdog;
81 int (*enqueue)(struct sk_buff *skb, struct Qdisc *sch,
82 struct sk_buff **to_free);
83 struct sk_buff *(*dequeue)(struct Qdisc *sch);
84 struct Qdisc *qdisc;
85 struct list_head cbs_list;
86};
87
88static int cbs_child_enqueue(struct sk_buff *skb, struct Qdisc *sch,
89 struct Qdisc *child,
90 struct sk_buff **to_free)
91{
92 unsigned int len = qdisc_pkt_len(skb);
93 int err;
94
95 err = child->ops->enqueue(skb, child, to_free);
96 if (err != NET_XMIT_SUCCESS)
97 return err;
98
99 sch->qstats.backlog += len;
100 sch->q.qlen++;
101
102 return NET_XMIT_SUCCESS;
103}
104
105static int cbs_enqueue_offload(struct sk_buff *skb, struct Qdisc *sch,
106 struct sk_buff **to_free)
107{
108 struct cbs_sched_data *q = qdisc_priv(sch);
109 struct Qdisc *qdisc = q->qdisc;
110
111 return cbs_child_enqueue(skb, sch, qdisc, to_free);
112}
113
114static int cbs_enqueue_soft(struct sk_buff *skb, struct Qdisc *sch,
115 struct sk_buff **to_free)
116{
117 struct cbs_sched_data *q = qdisc_priv(sch);
118 struct Qdisc *qdisc = q->qdisc;
119
120 if (sch->q.qlen == 0 && q->credits > 0) {
121 /* We need to stop accumulating credits when there's
122 * no enqueued packets and q->credits is positive.
123 */
124 q->credits = 0;
125 q->last = ktime_get_ns();
126 }
127
128 return cbs_child_enqueue(skb, sch, qdisc, to_free);
129}
130
131static int cbs_enqueue(struct sk_buff *skb, struct Qdisc *sch,
132 struct sk_buff **to_free)
133{
134 struct cbs_sched_data *q = qdisc_priv(sch);
135
136 return q->enqueue(skb, sch, to_free);
137}
138
139/* timediff is in ns, slope is in bytes/s */
140static s64 timediff_to_credits(s64 timediff, s64 slope)
141{
142 return div64_s64(timediff * slope, NSEC_PER_SEC);
143}
144
145static s64 delay_from_credits(s64 credits, s64 slope)
146{
147 if (unlikely(slope == 0))
148 return S64_MAX;
149
150 return div64_s64(-credits * NSEC_PER_SEC, slope);
151}
152
153static s64 credits_from_len(unsigned int len, s64 slope, s64 port_rate)
154{
155 if (unlikely(port_rate == 0))
156 return S64_MAX;
157
158 return div64_s64(len * slope, port_rate);
159}
160
161static struct sk_buff *cbs_child_dequeue(struct Qdisc *sch, struct Qdisc *child)
162{
163 struct sk_buff *skb;
164
165 skb = child->ops->dequeue(child);
166 if (!skb)
167 return NULL;
168
169 qdisc_qstats_backlog_dec(sch, skb);
170 qdisc_bstats_update(sch, skb);
171 sch->q.qlen--;
172
173 return skb;
174}
175
176static struct sk_buff *cbs_dequeue_soft(struct Qdisc *sch)
177{
178 struct cbs_sched_data *q = qdisc_priv(sch);
179 struct Qdisc *qdisc = q->qdisc;
180 s64 now = ktime_get_ns();
181 struct sk_buff *skb;
182 s64 credits;
183 int len;
184
185 /* The previous packet is still being sent */
186 if (now < q->last) {
187 qdisc_watchdog_schedule_ns(&q->watchdog, q->last);
188 return NULL;
189 }
190 if (q->credits < 0) {
191 credits = timediff_to_credits(now - q->last, q->idleslope);
192
193 credits = q->credits + credits;
194 q->credits = min_t(s64, credits, q->hicredit);
195
196 if (q->credits < 0) {
197 s64 delay;
198
199 delay = delay_from_credits(q->credits, q->idleslope);
200 qdisc_watchdog_schedule_ns(&q->watchdog, now + delay);
201
202 q->last = now;
203
204 return NULL;
205 }
206 }
207 skb = cbs_child_dequeue(sch, qdisc);
208 if (!skb)
209 return NULL;
210
211 len = qdisc_pkt_len(skb);
212
213 /* As sendslope is a negative number, this will decrease the
214 * amount of q->credits.
215 */
216 credits = credits_from_len(len, q->sendslope,
217 atomic64_read(&q->port_rate));
218 credits += q->credits;
219
220 q->credits = max_t(s64, credits, q->locredit);
221 /* Estimate of the transmission of the last byte of the packet in ns */
222 if (unlikely(atomic64_read(&q->port_rate) == 0))
223 q->last = now;
224 else
225 q->last = now + div64_s64(len * NSEC_PER_SEC,
226 atomic64_read(&q->port_rate));
227
228 return skb;
229}
230
231static struct sk_buff *cbs_dequeue_offload(struct Qdisc *sch)
232{
233 struct cbs_sched_data *q = qdisc_priv(sch);
234 struct Qdisc *qdisc = q->qdisc;
235
236 return cbs_child_dequeue(sch, qdisc);
237}
238
239static struct sk_buff *cbs_dequeue(struct Qdisc *sch)
240{
241 struct cbs_sched_data *q = qdisc_priv(sch);
242
243 return q->dequeue(sch);
244}
245
246static const struct nla_policy cbs_policy[TCA_CBS_MAX + 1] = {
247 [TCA_CBS_PARMS] = { .len = sizeof(struct tc_cbs_qopt) },
248};
249
250static void cbs_disable_offload(struct net_device *dev,
251 struct cbs_sched_data *q)
252{
253 struct tc_cbs_qopt_offload cbs = { };
254 const struct net_device_ops *ops;
255 int err;
256
257 if (!q->offload)
258 return;
259
260 q->enqueue = cbs_enqueue_soft;
261 q->dequeue = cbs_dequeue_soft;
262
263 ops = dev->netdev_ops;
264 if (!ops->ndo_setup_tc)
265 return;
266
267 cbs.queue = q->queue;
268 cbs.enable = 0;
269
270 err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_CBS, &cbs);
271 if (err < 0)
272 pr_warn("Couldn't disable CBS offload for queue %d\n",
273 cbs.queue);
274}
275
276static int cbs_enable_offload(struct net_device *dev, struct cbs_sched_data *q,
277 const struct tc_cbs_qopt *opt,
278 struct netlink_ext_ack *extack)
279{
280 const struct net_device_ops *ops = dev->netdev_ops;
281 struct tc_cbs_qopt_offload cbs = { };
282 int err;
283
284 if (!ops->ndo_setup_tc) {
285 NL_SET_ERR_MSG(extack, "Specified device does not support cbs offload");
286 return -EOPNOTSUPP;
287 }
288
289 cbs.queue = q->queue;
290
291 cbs.enable = 1;
292 cbs.hicredit = opt->hicredit;
293 cbs.locredit = opt->locredit;
294 cbs.idleslope = opt->idleslope;
295 cbs.sendslope = opt->sendslope;
296
297 err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_CBS, &cbs);
298 if (err < 0) {
299 NL_SET_ERR_MSG(extack, "Specified device failed to setup cbs hardware offload");
300 return err;
301 }
302
303 q->enqueue = cbs_enqueue_offload;
304 q->dequeue = cbs_dequeue_offload;
305
306 return 0;
307}
308
309static void cbs_set_port_rate(struct net_device *dev, struct cbs_sched_data *q)
310{
311 struct ethtool_link_ksettings ecmd;
312 int speed = SPEED_10;
313 int port_rate;
314 int err;
315
316 err = __ethtool_get_link_ksettings(dev, &ecmd);
317 if (err < 0)
318 goto skip;
319
320 if (ecmd.base.speed && ecmd.base.speed != SPEED_UNKNOWN)
321 speed = ecmd.base.speed;
322
323skip:
324 port_rate = speed * 1000 * BYTES_PER_KBIT;
325
326 atomic64_set(&q->port_rate, port_rate);
327 netdev_dbg(dev, "cbs: set %s's port_rate to: %lld, linkspeed: %d\n",
328 dev->name, (long long)atomic64_read(&q->port_rate),
329 ecmd.base.speed);
330}
331
332static int cbs_dev_notifier(struct notifier_block *nb, unsigned long event,
333 void *ptr)
334{
335 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
336 struct cbs_sched_data *q;
337 struct net_device *qdev;
338 bool found = false;
339
340 ASSERT_RTNL();
341
342 if (event != NETDEV_UP && event != NETDEV_CHANGE)
343 return NOTIFY_DONE;
344
345 spin_lock(&cbs_list_lock);
346 list_for_each_entry(q, &cbs_list, cbs_list) {
347 qdev = qdisc_dev(q->qdisc);
348 if (qdev == dev) {
349 found = true;
350 break;
351 }
352 }
353 spin_unlock(&cbs_list_lock);
354
355 if (found)
356 cbs_set_port_rate(dev, q);
357
358 return NOTIFY_DONE;
359}
360
361static int cbs_change(struct Qdisc *sch, struct nlattr *opt,
362 struct netlink_ext_ack *extack)
363{
364 struct cbs_sched_data *q = qdisc_priv(sch);
365 struct net_device *dev = qdisc_dev(sch);
366 struct nlattr *tb[TCA_CBS_MAX + 1];
367 struct tc_cbs_qopt *qopt;
368 int err;
369
370 err = nla_parse_nested_deprecated(tb, TCA_CBS_MAX, opt, cbs_policy,
371 extack);
372 if (err < 0)
373 return err;
374
375 if (!tb[TCA_CBS_PARMS]) {
376 NL_SET_ERR_MSG(extack, "Missing CBS parameter which are mandatory");
377 return -EINVAL;
378 }
379
380 qopt = nla_data(tb[TCA_CBS_PARMS]);
381
382 if (!qopt->offload) {
383 cbs_set_port_rate(dev, q);
384 cbs_disable_offload(dev, q);
385 } else {
386 err = cbs_enable_offload(dev, q, qopt, extack);
387 if (err < 0)
388 return err;
389 }
390
391 /* Everything went OK, save the parameters used. */
392 q->hicredit = qopt->hicredit;
393 q->locredit = qopt->locredit;
394 q->idleslope = qopt->idleslope * BYTES_PER_KBIT;
395 q->sendslope = qopt->sendslope * BYTES_PER_KBIT;
396 q->offload = qopt->offload;
397
398 return 0;
399}
400
401static int cbs_init(struct Qdisc *sch, struct nlattr *opt,
402 struct netlink_ext_ack *extack)
403{
404 struct cbs_sched_data *q = qdisc_priv(sch);
405 struct net_device *dev = qdisc_dev(sch);
406
407 if (!opt) {
408 NL_SET_ERR_MSG(extack, "Missing CBS qdisc options which are mandatory");
409 return -EINVAL;
410 }
411
412 q->qdisc = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
413 sch->handle, extack);
414 if (!q->qdisc)
415 return -ENOMEM;
416
417 spin_lock(&cbs_list_lock);
418 list_add(&q->cbs_list, &cbs_list);
419 spin_unlock(&cbs_list_lock);
420
421 qdisc_hash_add(q->qdisc, false);
422
423 q->queue = sch->dev_queue - netdev_get_tx_queue(dev, 0);
424
425 q->enqueue = cbs_enqueue_soft;
426 q->dequeue = cbs_dequeue_soft;
427
428 qdisc_watchdog_init(&q->watchdog, sch);
429
430 return cbs_change(sch, opt, extack);
431}
432
433static void cbs_destroy(struct Qdisc *sch)
434{
435 struct cbs_sched_data *q = qdisc_priv(sch);
436 struct net_device *dev = qdisc_dev(sch);
437
438 /* Nothing to do if we couldn't create the underlying qdisc */
439 if (!q->qdisc)
440 return;
441
442 qdisc_watchdog_cancel(&q->watchdog);
443 cbs_disable_offload(dev, q);
444
445 spin_lock(&cbs_list_lock);
446 list_del(&q->cbs_list);
447 spin_unlock(&cbs_list_lock);
448
449 qdisc_put(q->qdisc);
450}
451
452static int cbs_dump(struct Qdisc *sch, struct sk_buff *skb)
453{
454 struct cbs_sched_data *q = qdisc_priv(sch);
455 struct tc_cbs_qopt opt = { };
456 struct nlattr *nest;
457
458 nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
459 if (!nest)
460 goto nla_put_failure;
461
462 opt.hicredit = q->hicredit;
463 opt.locredit = q->locredit;
464 opt.sendslope = div64_s64(q->sendslope, BYTES_PER_KBIT);
465 opt.idleslope = div64_s64(q->idleslope, BYTES_PER_KBIT);
466 opt.offload = q->offload;
467
468 if (nla_put(skb, TCA_CBS_PARMS, sizeof(opt), &opt))
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 cbs_dump_class(struct Qdisc *sch, unsigned long cl,
479 struct sk_buff *skb, struct tcmsg *tcm)
480{
481 struct cbs_sched_data *q = qdisc_priv(sch);
482
483 if (cl != 1 || !q->qdisc) /* only one class */
484 return -ENOENT;
485
486 tcm->tcm_handle |= TC_H_MIN(1);
487 tcm->tcm_info = q->qdisc->handle;
488
489 return 0;
490}
491
492static int cbs_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
493 struct Qdisc **old, struct netlink_ext_ack *extack)
494{
495 struct cbs_sched_data *q = qdisc_priv(sch);
496
497 if (!new) {
498 new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
499 sch->handle, NULL);
500 if (!new)
501 new = &noop_qdisc;
502 }
503
504 *old = qdisc_replace(sch, new, &q->qdisc);
505 return 0;
506}
507
508static struct Qdisc *cbs_leaf(struct Qdisc *sch, unsigned long arg)
509{
510 struct cbs_sched_data *q = qdisc_priv(sch);
511
512 return q->qdisc;
513}
514
515static unsigned long cbs_find(struct Qdisc *sch, u32 classid)
516{
517 return 1;
518}
519
520static void cbs_walk(struct Qdisc *sch, struct qdisc_walker *walker)
521{
522 if (!walker->stop) {
523 tc_qdisc_stats_dump(sch, 1, walker);
524 }
525}
526
527static const struct Qdisc_class_ops cbs_class_ops = {
528 .graft = cbs_graft,
529 .leaf = cbs_leaf,
530 .find = cbs_find,
531 .walk = cbs_walk,
532 .dump = cbs_dump_class,
533};
534
535static struct Qdisc_ops cbs_qdisc_ops __read_mostly = {
536 .id = "cbs",
537 .cl_ops = &cbs_class_ops,
538 .priv_size = sizeof(struct cbs_sched_data),
539 .enqueue = cbs_enqueue,
540 .dequeue = cbs_dequeue,
541 .peek = qdisc_peek_dequeued,
542 .init = cbs_init,
543 .reset = qdisc_reset_queue,
544 .destroy = cbs_destroy,
545 .change = cbs_change,
546 .dump = cbs_dump,
547 .owner = THIS_MODULE,
548};
549
550static struct notifier_block cbs_device_notifier = {
551 .notifier_call = cbs_dev_notifier,
552};
553
554static int __init cbs_module_init(void)
555{
556 int err;
557
558 err = register_netdevice_notifier(&cbs_device_notifier);
559 if (err)
560 return err;
561
562 err = register_qdisc(&cbs_qdisc_ops);
563 if (err)
564 unregister_netdevice_notifier(&cbs_device_notifier);
565
566 return err;
567}
568
569static void __exit cbs_module_exit(void)
570{
571 unregister_qdisc(&cbs_qdisc_ops);
572 unregister_netdevice_notifier(&cbs_device_notifier);
573}
574module_init(cbs_module_init)
575module_exit(cbs_module_exit)
576MODULE_LICENSE("GPL");