xref: /openbmc/linux/net/sched/sch_etf.c (revision 6f69e2a3) 
1 // SPDX-License-Identifier: GPL-2.0
2 
3 /* net/sched/sch_etf.c  Earliest TxTime First queueing discipline.
4  *
5  * Authors:	Jesus Sanchez-Palencia <jesus.sanchez-palencia@intel.com>
6  *		Vinicius Costa Gomes <vinicius.gomes@intel.com>
7  */
8 
9 #include <linux/module.h>
10 #include <linux/types.h>
11 #include <linux/kernel.h>
12 #include <linux/string.h>
13 #include <linux/errno.h>
14 #include <linux/errqueue.h>
15 #include <linux/rbtree.h>
16 #include <linux/skbuff.h>
17 #include <linux/posix-timers.h>
18 #include <net/netlink.h>
19 #include <net/sch_generic.h>
20 #include <net/pkt_sched.h>
21 #include <net/sock.h>
22 
23 #define DEADLINE_MODE_IS_ON(x) ((x)->flags & TC_ETF_DEADLINE_MODE_ON)
24 #define OFFLOAD_IS_ON(x) ((x)->flags & TC_ETF_OFFLOAD_ON)
25 #define SKIP_SOCK_CHECK_IS_SET(x) ((x)->flags & TC_ETF_SKIP_SOCK_CHECK)
26 
27 struct etf_sched_data {
28 	bool offload;
29 	bool deadline_mode;
30 	bool skip_sock_check;
31 	int clockid;
32 	int queue;
33 	s32 delta; /* in ns */
34 	ktime_t last; /* The txtime of the last skb sent to the netdevice. */
35 	struct rb_root_cached head;
36 	struct qdisc_watchdog watchdog;
37 	ktime_t (*get_time)(void);
38 };
39 
40 static const struct nla_policy etf_policy[TCA_ETF_MAX + 1] = {
41 	[TCA_ETF_PARMS]	= { .len = sizeof(struct tc_etf_qopt) },
42 };
43 
44 static inline int validate_input_params(struct tc_etf_qopt *qopt,
45 					struct netlink_ext_ack *extack)
46 {
47 	/* Check if params comply to the following rules:
48 	 *	* Clockid and delta must be valid.
49 	 *
50 	 *	* Dynamic clockids are not supported.
51 	 *
52 	 *	* Delta must be a positive integer.
53 	 *
54 	 * Also note that for the HW offload case, we must
55 	 * expect that system clocks have been synchronized to PHC.
56 	 */
57 	if (qopt->clockid < 0) {
58 		NL_SET_ERR_MSG(extack, "Dynamic clockids are not supported");
59 		return -ENOTSUPP;
60 	}
61 
62 	if (qopt->clockid != CLOCK_TAI) {
63 		NL_SET_ERR_MSG(extack, "Invalid clockid. CLOCK_TAI must be used");
64 		return -EINVAL;
65 	}
66 
67 	if (qopt->delta < 0) {
68 		NL_SET_ERR_MSG(extack, "Delta must be positive");
69 		return -EINVAL;
70 	}
71 
72 	return 0;
73 }
74 
75 static bool is_packet_valid(struct Qdisc *sch, struct sk_buff *nskb)
76 {
77 	struct etf_sched_data *q = qdisc_priv(sch);
78 	ktime_t txtime = nskb->tstamp;
79 	struct sock *sk = nskb->sk;
80 	ktime_t now;
81 
82 	if (q->skip_sock_check)
83 		goto skip;
84 
85 	if (!sk)
86 		return false;
87 
88 	if (!sock_flag(sk, SOCK_TXTIME))
89 		return false;
90 
91 	/* We don't perform crosstimestamping.
92 	 * Drop if packet's clockid differs from qdisc's.
93 	 */
94 	if (sk->sk_clockid != q->clockid)
95 		return false;
96 
97 	if (sk->sk_txtime_deadline_mode != q->deadline_mode)
98 		return false;
99 
100 skip:
101 	now = q->get_time();
102 	if (ktime_before(txtime, now) || ktime_before(txtime, q->last))
103 		return false;
104 
105 	return true;
106 }
107 
108 static struct sk_buff *etf_peek_timesortedlist(struct Qdisc *sch)
109 {
110 	struct etf_sched_data *q = qdisc_priv(sch);
111 	struct rb_node *p;
112 
113 	p = rb_first_cached(&q->head);
114 	if (!p)
115 		return NULL;
116 
117 	return rb_to_skb(p);
118 }
119 
120 static void reset_watchdog(struct Qdisc *sch)
121 {
122 	struct etf_sched_data *q = qdisc_priv(sch);
123 	struct sk_buff *skb = etf_peek_timesortedlist(sch);
124 	ktime_t next;
125 
126 	if (!skb) {
127 		qdisc_watchdog_cancel(&q->watchdog);
128 		return;
129 	}
130 
131 	next = ktime_sub_ns(skb->tstamp, q->delta);
132 	qdisc_watchdog_schedule_ns(&q->watchdog, ktime_to_ns(next));
133 }
134 
135 static void report_sock_error(struct sk_buff *skb, u32 err, u8 code)
136 {
137 	struct sock_exterr_skb *serr;
138 	struct sk_buff *clone;
139 	ktime_t txtime = skb->tstamp;
140 
141 	if (!skb->sk || !(skb->sk->sk_txtime_report_errors))
142 		return;
143 
144 	clone = skb_clone(skb, GFP_ATOMIC);
145 	if (!clone)
146 		return;
147 
148 	serr = SKB_EXT_ERR(clone);
149 	serr->ee.ee_errno = err;
150 	serr->ee.ee_origin = SO_EE_ORIGIN_TXTIME;
151 	serr->ee.ee_type = 0;
152 	serr->ee.ee_code = code;
153 	serr->ee.ee_pad = 0;
154 	serr->ee.ee_data = (txtime >> 32); /* high part of tstamp */
155 	serr->ee.ee_info = txtime; /* low part of tstamp */
156 
157 	if (sock_queue_err_skb(skb->sk, clone))
158 		kfree_skb(clone);
159 }
160 
161 static int etf_enqueue_timesortedlist(struct sk_buff *nskb, struct Qdisc *sch,
162 				      struct sk_buff **to_free)
163 {
164 	struct etf_sched_data *q = qdisc_priv(sch);
165 	struct rb_node **p = &q->head.rb_root.rb_node, *parent = NULL;
166 	ktime_t txtime = nskb->tstamp;
167 	bool leftmost = true;
168 
169 	if (!is_packet_valid(sch, nskb)) {
170 		report_sock_error(nskb, EINVAL,
171 				  SO_EE_CODE_TXTIME_INVALID_PARAM);
172 		return qdisc_drop(nskb, sch, to_free);
173 	}
174 
175 	while (*p) {
176 		struct sk_buff *skb;
177 
178 		parent = *p;
179 		skb = rb_to_skb(parent);
180 		if (ktime_compare(txtime, skb->tstamp) >= 0) {
181 			p = &parent->rb_right;
182 			leftmost = false;
183 		} else {
184 			p = &parent->rb_left;
185 		}
186 	}
187 	rb_link_node(&nskb->rbnode, parent, p);
188 	rb_insert_color_cached(&nskb->rbnode, &q->head, leftmost);
189 
190 	qdisc_qstats_backlog_inc(sch, nskb);
191 	sch->q.qlen++;
192 
193 	/* Now we may need to re-arm the qdisc watchdog for the next packet. */
194 	reset_watchdog(sch);
195 
196 	return NET_XMIT_SUCCESS;
197 }
198 
199 static void timesortedlist_drop(struct Qdisc *sch, struct sk_buff *skb,
200 				ktime_t now)
201 {
202 	struct etf_sched_data *q = qdisc_priv(sch);
203 	struct sk_buff *to_free = NULL;
204 	struct sk_buff *tmp = NULL;
205 
206 	skb_rbtree_walk_from_safe(skb, tmp) {
207 		if (ktime_after(skb->tstamp, now))
208 			break;
209 
210 		rb_erase_cached(&skb->rbnode, &q->head);
211 
212 		/* The rbnode field in the skb re-uses these fields, now that
213 		 * we are done with the rbnode, reset them.
214 		 */
215 		skb->next = NULL;
216 		skb->prev = NULL;
217 		skb->dev = qdisc_dev(sch);
218 
219 		report_sock_error(skb, ECANCELED, SO_EE_CODE_TXTIME_MISSED);
220 
221 		qdisc_qstats_backlog_dec(sch, skb);
222 		qdisc_drop(skb, sch, &to_free);
223 		qdisc_qstats_overlimit(sch);
224 		sch->q.qlen--;
225 	}
226 
227 	kfree_skb_list(to_free);
228 }
229 
230 static void timesortedlist_remove(struct Qdisc *sch, struct sk_buff *skb)
231 {
232 	struct etf_sched_data *q = qdisc_priv(sch);
233 
234 	rb_erase_cached(&skb->rbnode, &q->head);
235 
236 	/* The rbnode field in the skb re-uses these fields, now that
237 	 * we are done with the rbnode, reset them.
238 	 */
239 	skb->next = NULL;
240 	skb->prev = NULL;
241 	skb->dev = qdisc_dev(sch);
242 
243 	qdisc_qstats_backlog_dec(sch, skb);
244 
245 	qdisc_bstats_update(sch, skb);
246 
247 	q->last = skb->tstamp;
248 
249 	sch->q.qlen--;
250 }
251 
252 static struct sk_buff *etf_dequeue_timesortedlist(struct Qdisc *sch)
253 {
254 	struct etf_sched_data *q = qdisc_priv(sch);
255 	struct sk_buff *skb;
256 	ktime_t now, next;
257 
258 	skb = etf_peek_timesortedlist(sch);
259 	if (!skb)
260 		return NULL;
261 
262 	now = q->get_time();
263 
264 	/* Drop if packet has expired while in queue. */
265 	if (ktime_before(skb->tstamp, now)) {
266 		timesortedlist_drop(sch, skb, now);
267 		skb = NULL;
268 		goto out;
269 	}
270 
271 	/* When in deadline mode, dequeue as soon as possible and change the
272 	 * txtime from deadline to (now + delta).
273 	 */
274 	if (q->deadline_mode) {
275 		timesortedlist_remove(sch, skb);
276 		skb->tstamp = now;
277 		goto out;
278 	}
279 
280 	next = ktime_sub_ns(skb->tstamp, q->delta);
281 
282 	/* Dequeue only if now is within the [txtime - delta, txtime] range. */
283 	if (ktime_after(now, next))
284 		timesortedlist_remove(sch, skb);
285 	else
286 		skb = NULL;
287 
288 out:
289 	/* Now we may need to re-arm the qdisc watchdog for the next packet. */
290 	reset_watchdog(sch);
291 
292 	return skb;
293 }
294 
295 static void etf_disable_offload(struct net_device *dev,
296 				struct etf_sched_data *q)
297 {
298 	struct tc_etf_qopt_offload etf = { };
299 	const struct net_device_ops *ops;
300 	int err;
301 
302 	if (!q->offload)
303 		return;
304 
305 	ops = dev->netdev_ops;
306 	if (!ops->ndo_setup_tc)
307 		return;
308 
309 	etf.queue = q->queue;
310 	etf.enable = 0;
311 
312 	err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_ETF, &etf);
313 	if (err < 0)
314 		pr_warn("Couldn't disable ETF offload for queue %d\n",
315 			etf.queue);
316 }
317 
318 static int etf_enable_offload(struct net_device *dev, struct etf_sched_data *q,
319 			      struct netlink_ext_ack *extack)
320 {
321 	const struct net_device_ops *ops = dev->netdev_ops;
322 	struct tc_etf_qopt_offload etf = { };
323 	int err;
324 
325 	if (q->offload)
326 		return 0;
327 
328 	if (!ops->ndo_setup_tc) {
329 		NL_SET_ERR_MSG(extack, "Specified device does not support ETF offload");
330 		return -EOPNOTSUPP;
331 	}
332 
333 	etf.queue = q->queue;
334 	etf.enable = 1;
335 
336 	err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_ETF, &etf);
337 	if (err < 0) {
338 		NL_SET_ERR_MSG(extack, "Specified device failed to setup ETF hardware offload");
339 		return err;
340 	}
341 
342 	return 0;
343 }
344 
345 static int etf_init(struct Qdisc *sch, struct nlattr *opt,
346 		    struct netlink_ext_ack *extack)
347 {
348 	struct etf_sched_data *q = qdisc_priv(sch);
349 	struct net_device *dev = qdisc_dev(sch);
350 	struct nlattr *tb[TCA_ETF_MAX + 1];
351 	struct tc_etf_qopt *qopt;
352 	int err;
353 
354 	if (!opt) {
355 		NL_SET_ERR_MSG(extack,
356 			       "Missing ETF qdisc options which are mandatory");
357 		return -EINVAL;
358 	}
359 
360 	err = nla_parse_nested_deprecated(tb, TCA_ETF_MAX, opt, etf_policy,
361 					  extack);
362 	if (err < 0)
363 		return err;
364 
365 	if (!tb[TCA_ETF_PARMS]) {
366 		NL_SET_ERR_MSG(extack, "Missing mandatory ETF parameters");
367 		return -EINVAL;
368 	}
369 
370 	qopt = nla_data(tb[TCA_ETF_PARMS]);
371 
372 	pr_debug("delta %d clockid %d offload %s deadline %s\n",
373 		 qopt->delta, qopt->clockid,
374 		 OFFLOAD_IS_ON(qopt) ? "on" : "off",
375 		 DEADLINE_MODE_IS_ON(qopt) ? "on" : "off");
376 
377 	err = validate_input_params(qopt, extack);
378 	if (err < 0)
379 		return err;
380 
381 	q->queue = sch->dev_queue - netdev_get_tx_queue(dev, 0);
382 
383 	if (OFFLOAD_IS_ON(qopt)) {
384 		err = etf_enable_offload(dev, q, extack);
385 		if (err < 0)
386 			return err;
387 	}
388 
389 	/* Everything went OK, save the parameters used. */
390 	q->delta = qopt->delta;
391 	q->clockid = qopt->clockid;
392 	q->offload = OFFLOAD_IS_ON(qopt);
393 	q->deadline_mode = DEADLINE_MODE_IS_ON(qopt);
394 	q->skip_sock_check = SKIP_SOCK_CHECK_IS_SET(qopt);
395 
396 	switch (q->clockid) {
397 	case CLOCK_REALTIME:
398 		q->get_time = ktime_get_real;
399 		break;
400 	case CLOCK_MONOTONIC:
401 		q->get_time = ktime_get;
402 		break;
403 	case CLOCK_BOOTTIME:
404 		q->get_time = ktime_get_boottime;
405 		break;
406 	case CLOCK_TAI:
407 		q->get_time = ktime_get_clocktai;
408 		break;
409 	default:
410 		NL_SET_ERR_MSG(extack, "Clockid is not supported");
411 		return -ENOTSUPP;
412 	}
413 
414 	qdisc_watchdog_init_clockid(&q->watchdog, sch, q->clockid);
415 
416 	return 0;
417 }
418 
419 static void timesortedlist_clear(struct Qdisc *sch)
420 {
421 	struct etf_sched_data *q = qdisc_priv(sch);
422 	struct rb_node *p = rb_first_cached(&q->head);
423 
424 	while (p) {
425 		struct sk_buff *skb = rb_to_skb(p);
426 
427 		p = rb_next(p);
428 
429 		rb_erase_cached(&skb->rbnode, &q->head);
430 		rtnl_kfree_skbs(skb, skb);
431 		sch->q.qlen--;
432 	}
433 }
434 
435 static void etf_reset(struct Qdisc *sch)
436 {
437 	struct etf_sched_data *q = qdisc_priv(sch);
438 
439 	/* Only cancel watchdog if it's been initialized. */
440 	if (q->watchdog.qdisc == sch)
441 		qdisc_watchdog_cancel(&q->watchdog);
442 
443 	/* No matter which mode we are on, it's safe to clear both lists. */
444 	timesortedlist_clear(sch);
445 	__qdisc_reset_queue(&sch->q);
446 
447 	sch->qstats.backlog = 0;
448 	sch->q.qlen = 0;
449 
450 	q->last = 0;
451 }
452 
453 static void etf_destroy(struct Qdisc *sch)
454 {
455 	struct etf_sched_data *q = qdisc_priv(sch);
456 	struct net_device *dev = qdisc_dev(sch);
457 
458 	/* Only cancel watchdog if it's been initialized. */
459 	if (q->watchdog.qdisc == sch)
460 		qdisc_watchdog_cancel(&q->watchdog);
461 
462 	etf_disable_offload(dev, q);
463 }
464 
465 static int etf_dump(struct Qdisc *sch, struct sk_buff *skb)
466 {
467 	struct etf_sched_data *q = qdisc_priv(sch);
468 	struct tc_etf_qopt opt = { };
469 	struct nlattr *nest;
470 
471 	nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
472 	if (!nest)
473 		goto nla_put_failure;
474 
475 	opt.delta = q->delta;
476 	opt.clockid = q->clockid;
477 	if (q->offload)
478 		opt.flags |= TC_ETF_OFFLOAD_ON;
479 
480 	if (q->deadline_mode)
481 		opt.flags |= TC_ETF_DEADLINE_MODE_ON;
482 
483 	if (q->skip_sock_check)
484 		opt.flags |= TC_ETF_SKIP_SOCK_CHECK;
485 
486 	if (nla_put(skb, TCA_ETF_PARMS, sizeof(opt), &opt))
487 		goto nla_put_failure;
488 
489 	return nla_nest_end(skb, nest);
490 
491 nla_put_failure:
492 	nla_nest_cancel(skb, nest);
493 	return -1;
494 }
495 
496 static struct Qdisc_ops etf_qdisc_ops __read_mostly = {
497 	.id		=	"etf",
498 	.priv_size	=	sizeof(struct etf_sched_data),
499 	.enqueue	=	etf_enqueue_timesortedlist,
500 	.dequeue	=	etf_dequeue_timesortedlist,
501 	.peek		=	etf_peek_timesortedlist,
502 	.init		=	etf_init,
503 	.reset		=	etf_reset,
504 	.destroy	=	etf_destroy,
505 	.dump		=	etf_dump,
506 	.owner		=	THIS_MODULE,
507 };
508 
509 static int __init etf_module_init(void)
510 {
511 	return register_qdisc(&etf_qdisc_ops);
512 }
513 
514 static void __exit etf_module_exit(void)
515 {
516 	unregister_qdisc(&etf_qdisc_ops);
517 }
518 module_init(etf_module_init)
519 module_exit(etf_module_exit)
520 MODULE_LICENSE("GPL");
521