xref: /openbmc/linux/net/sched/sch_drr.c (revision 19c233b7) 
1 /*
2  * net/sched/sch_drr.c         Deficit Round Robin scheduler
3  *
4  * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * version 2 as published by the Free Software Foundation.
9  */
10 
11 #include <linux/module.h>
12 #include <linux/slab.h>
13 #include <linux/init.h>
14 #include <linux/errno.h>
15 #include <linux/netdevice.h>
16 #include <linux/pkt_sched.h>
17 #include <net/sch_generic.h>
18 #include <net/pkt_sched.h>
19 #include <net/pkt_cls.h>
20 
21 struct drr_class {
22 	struct Qdisc_class_common	common;
23 	unsigned int			refcnt;
24 	unsigned int			filter_cnt;
25 
26 	struct gnet_stats_basic_packed		bstats;
27 	struct gnet_stats_queue		qstats;
28 	struct gnet_stats_rate_est64	rate_est;
29 	struct list_head		alist;
30 	struct Qdisc			*qdisc;
31 
32 	u32				quantum;
33 	u32				deficit;
34 };
35 
36 struct drr_sched {
37 	struct list_head		active;
38 	struct tcf_proto __rcu		*filter_list;
39 	struct Qdisc_class_hash		clhash;
40 };
41 
42 static struct drr_class *drr_find_class(struct Qdisc *sch, u32 classid)
43 {
44 	struct drr_sched *q = qdisc_priv(sch);
45 	struct Qdisc_class_common *clc;
46 
47 	clc = qdisc_class_find(&q->clhash, classid);
48 	if (clc == NULL)
49 		return NULL;
50 	return container_of(clc, struct drr_class, common);
51 }
52 
53 static void drr_purge_queue(struct drr_class *cl)
54 {
55 	unsigned int len = cl->qdisc->q.qlen;
56 
57 	qdisc_reset(cl->qdisc);
58 	qdisc_tree_decrease_qlen(cl->qdisc, len);
59 }
60 
61 static const struct nla_policy drr_policy[TCA_DRR_MAX + 1] = {
62 	[TCA_DRR_QUANTUM]	= { .type = NLA_U32 },
63 };
64 
65 static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
66 			    struct nlattr **tca, unsigned long *arg)
67 {
68 	struct drr_sched *q = qdisc_priv(sch);
69 	struct drr_class *cl = (struct drr_class *)*arg;
70 	struct nlattr *opt = tca[TCA_OPTIONS];
71 	struct nlattr *tb[TCA_DRR_MAX + 1];
72 	u32 quantum;
73 	int err;
74 
75 	if (!opt)
76 		return -EINVAL;
77 
78 	err = nla_parse_nested(tb, TCA_DRR_MAX, opt, drr_policy);
79 	if (err < 0)
80 		return err;
81 
82 	if (tb[TCA_DRR_QUANTUM]) {
83 		quantum = nla_get_u32(tb[TCA_DRR_QUANTUM]);
84 		if (quantum == 0)
85 			return -EINVAL;
86 	} else
87 		quantum = psched_mtu(qdisc_dev(sch));
88 
89 	if (cl != NULL) {
90 		if (tca[TCA_RATE]) {
91 			err = gen_replace_estimator(&cl->bstats, NULL,
92 						    &cl->rate_est,
93 						    qdisc_root_sleeping_lock(sch),
94 						    tca[TCA_RATE]);
95 			if (err)
96 				return err;
97 		}
98 
99 		sch_tree_lock(sch);
100 		if (tb[TCA_DRR_QUANTUM])
101 			cl->quantum = quantum;
102 		sch_tree_unlock(sch);
103 
104 		return 0;
105 	}
106 
107 	cl = kzalloc(sizeof(struct drr_class), GFP_KERNEL);
108 	if (cl == NULL)
109 		return -ENOBUFS;
110 
111 	cl->refcnt	   = 1;
112 	cl->common.classid = classid;
113 	cl->quantum	   = quantum;
114 	cl->qdisc	   = qdisc_create_dflt(sch->dev_queue,
115 					       &pfifo_qdisc_ops, classid);
116 	if (cl->qdisc == NULL)
117 		cl->qdisc = &noop_qdisc;
118 
119 	if (tca[TCA_RATE]) {
120 		err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est,
121 					    qdisc_root_sleeping_lock(sch),
122 					    tca[TCA_RATE]);
123 		if (err) {
124 			qdisc_destroy(cl->qdisc);
125 			kfree(cl);
126 			return err;
127 		}
128 	}
129 
130 	sch_tree_lock(sch);
131 	qdisc_class_hash_insert(&q->clhash, &cl->common);
132 	sch_tree_unlock(sch);
133 
134 	qdisc_class_hash_grow(sch, &q->clhash);
135 
136 	*arg = (unsigned long)cl;
137 	return 0;
138 }
139 
140 static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl)
141 {
142 	gen_kill_estimator(&cl->bstats, &cl->rate_est);
143 	qdisc_destroy(cl->qdisc);
144 	kfree(cl);
145 }
146 
147 static int drr_delete_class(struct Qdisc *sch, unsigned long arg)
148 {
149 	struct drr_sched *q = qdisc_priv(sch);
150 	struct drr_class *cl = (struct drr_class *)arg;
151 
152 	if (cl->filter_cnt > 0)
153 		return -EBUSY;
154 
155 	sch_tree_lock(sch);
156 
157 	drr_purge_queue(cl);
158 	qdisc_class_hash_remove(&q->clhash, &cl->common);
159 
160 	BUG_ON(--cl->refcnt == 0);
161 	/*
162 	 * This shouldn't happen: we "hold" one cops->get() when called
163 	 * from tc_ctl_tclass; the destroy method is done from cops->put().
164 	 */
165 
166 	sch_tree_unlock(sch);
167 	return 0;
168 }
169 
170 static unsigned long drr_get_class(struct Qdisc *sch, u32 classid)
171 {
172 	struct drr_class *cl = drr_find_class(sch, classid);
173 
174 	if (cl != NULL)
175 		cl->refcnt++;
176 
177 	return (unsigned long)cl;
178 }
179 
180 static void drr_put_class(struct Qdisc *sch, unsigned long arg)
181 {
182 	struct drr_class *cl = (struct drr_class *)arg;
183 
184 	if (--cl->refcnt == 0)
185 		drr_destroy_class(sch, cl);
186 }
187 
188 static struct tcf_proto __rcu **drr_tcf_chain(struct Qdisc *sch,
189 					      unsigned long cl)
190 {
191 	struct drr_sched *q = qdisc_priv(sch);
192 
193 	if (cl)
194 		return NULL;
195 
196 	return &q->filter_list;
197 }
198 
199 static unsigned long drr_bind_tcf(struct Qdisc *sch, unsigned long parent,
200 				  u32 classid)
201 {
202 	struct drr_class *cl = drr_find_class(sch, classid);
203 
204 	if (cl != NULL)
205 		cl->filter_cnt++;
206 
207 	return (unsigned long)cl;
208 }
209 
210 static void drr_unbind_tcf(struct Qdisc *sch, unsigned long arg)
211 {
212 	struct drr_class *cl = (struct drr_class *)arg;
213 
214 	cl->filter_cnt--;
215 }
216 
217 static int drr_graft_class(struct Qdisc *sch, unsigned long arg,
218 			   struct Qdisc *new, struct Qdisc **old)
219 {
220 	struct drr_class *cl = (struct drr_class *)arg;
221 
222 	if (new == NULL) {
223 		new = qdisc_create_dflt(sch->dev_queue,
224 					&pfifo_qdisc_ops, cl->common.classid);
225 		if (new == NULL)
226 			new = &noop_qdisc;
227 	}
228 
229 	sch_tree_lock(sch);
230 	drr_purge_queue(cl);
231 	*old = cl->qdisc;
232 	cl->qdisc = new;
233 	sch_tree_unlock(sch);
234 	return 0;
235 }
236 
237 static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg)
238 {
239 	struct drr_class *cl = (struct drr_class *)arg;
240 
241 	return cl->qdisc;
242 }
243 
244 static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg)
245 {
246 	struct drr_class *cl = (struct drr_class *)arg;
247 
248 	if (cl->qdisc->q.qlen == 0)
249 		list_del(&cl->alist);
250 }
251 
252 static int drr_dump_class(struct Qdisc *sch, unsigned long arg,
253 			  struct sk_buff *skb, struct tcmsg *tcm)
254 {
255 	struct drr_class *cl = (struct drr_class *)arg;
256 	struct nlattr *nest;
257 
258 	tcm->tcm_parent	= TC_H_ROOT;
259 	tcm->tcm_handle	= cl->common.classid;
260 	tcm->tcm_info	= cl->qdisc->handle;
261 
262 	nest = nla_nest_start(skb, TCA_OPTIONS);
263 	if (nest == NULL)
264 		goto nla_put_failure;
265 	if (nla_put_u32(skb, TCA_DRR_QUANTUM, cl->quantum))
266 		goto nla_put_failure;
267 	return nla_nest_end(skb, nest);
268 
269 nla_put_failure:
270 	nla_nest_cancel(skb, nest);
271 	return -EMSGSIZE;
272 }
273 
274 static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg,
275 				struct gnet_dump *d)
276 {
277 	struct drr_class *cl = (struct drr_class *)arg;
278 	__u32 qlen = cl->qdisc->q.qlen;
279 	struct tc_drr_stats xstats;
280 
281 	memset(&xstats, 0, sizeof(xstats));
282 	if (qlen)
283 		xstats.deficit = cl->deficit;
284 
285 	if (gnet_stats_copy_basic(d, NULL, &cl->bstats) < 0 ||
286 	    gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 ||
287 	    gnet_stats_copy_queue(d, NULL, &cl->qdisc->qstats, qlen) < 0)
288 		return -1;
289 
290 	return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
291 }
292 
293 static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg)
294 {
295 	struct drr_sched *q = qdisc_priv(sch);
296 	struct drr_class *cl;
297 	unsigned int i;
298 
299 	if (arg->stop)
300 		return;
301 
302 	for (i = 0; i < q->clhash.hashsize; i++) {
303 		hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
304 			if (arg->count < arg->skip) {
305 				arg->count++;
306 				continue;
307 			}
308 			if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
309 				arg->stop = 1;
310 				return;
311 			}
312 			arg->count++;
313 		}
314 	}
315 }
316 
317 static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch,
318 				      int *qerr)
319 {
320 	struct drr_sched *q = qdisc_priv(sch);
321 	struct drr_class *cl;
322 	struct tcf_result res;
323 	struct tcf_proto *fl;
324 	int result;
325 
326 	if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
327 		cl = drr_find_class(sch, skb->priority);
328 		if (cl != NULL)
329 			return cl;
330 	}
331 
332 	*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
333 	fl = rcu_dereference_bh(q->filter_list);
334 	result = tc_classify(skb, fl, &res);
335 	if (result >= 0) {
336 #ifdef CONFIG_NET_CLS_ACT
337 		switch (result) {
338 		case TC_ACT_QUEUED:
339 		case TC_ACT_STOLEN:
340 			*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
341 		case TC_ACT_SHOT:
342 			return NULL;
343 		}
344 #endif
345 		cl = (struct drr_class *)res.class;
346 		if (cl == NULL)
347 			cl = drr_find_class(sch, res.classid);
348 		return cl;
349 	}
350 	return NULL;
351 }
352 
353 static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch)
354 {
355 	struct drr_sched *q = qdisc_priv(sch);
356 	struct drr_class *cl;
357 	int err = 0;
358 
359 	cl = drr_classify(skb, sch, &err);
360 	if (cl == NULL) {
361 		if (err & __NET_XMIT_BYPASS)
362 			qdisc_qstats_drop(sch);
363 		kfree_skb(skb);
364 		return err;
365 	}
366 
367 	err = qdisc_enqueue(skb, cl->qdisc);
368 	if (unlikely(err != NET_XMIT_SUCCESS)) {
369 		if (net_xmit_drop_count(err)) {
370 			cl->qstats.drops++;
371 			qdisc_qstats_drop(sch);
372 		}
373 		return err;
374 	}
375 
376 	if (cl->qdisc->q.qlen == 1) {
377 		list_add_tail(&cl->alist, &q->active);
378 		cl->deficit = cl->quantum;
379 	}
380 
381 	sch->q.qlen++;
382 	return err;
383 }
384 
385 static struct sk_buff *drr_dequeue(struct Qdisc *sch)
386 {
387 	struct drr_sched *q = qdisc_priv(sch);
388 	struct drr_class *cl;
389 	struct sk_buff *skb;
390 	unsigned int len;
391 
392 	if (list_empty(&q->active))
393 		goto out;
394 	while (1) {
395 		cl = list_first_entry(&q->active, struct drr_class, alist);
396 		skb = cl->qdisc->ops->peek(cl->qdisc);
397 		if (skb == NULL) {
398 			qdisc_warn_nonwc(__func__, cl->qdisc);
399 			goto out;
400 		}
401 
402 		len = qdisc_pkt_len(skb);
403 		if (len <= cl->deficit) {
404 			cl->deficit -= len;
405 			skb = qdisc_dequeue_peeked(cl->qdisc);
406 			if (cl->qdisc->q.qlen == 0)
407 				list_del(&cl->alist);
408 
409 			bstats_update(&cl->bstats, skb);
410 			qdisc_bstats_update(sch, skb);
411 			sch->q.qlen--;
412 			return skb;
413 		}
414 
415 		cl->deficit += cl->quantum;
416 		list_move_tail(&cl->alist, &q->active);
417 	}
418 out:
419 	return NULL;
420 }
421 
422 static unsigned int drr_drop(struct Qdisc *sch)
423 {
424 	struct drr_sched *q = qdisc_priv(sch);
425 	struct drr_class *cl;
426 	unsigned int len;
427 
428 	list_for_each_entry(cl, &q->active, alist) {
429 		if (cl->qdisc->ops->drop) {
430 			len = cl->qdisc->ops->drop(cl->qdisc);
431 			if (len > 0) {
432 				sch->q.qlen--;
433 				if (cl->qdisc->q.qlen == 0)
434 					list_del(&cl->alist);
435 				return len;
436 			}
437 		}
438 	}
439 	return 0;
440 }
441 
442 static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
443 {
444 	struct drr_sched *q = qdisc_priv(sch);
445 	int err;
446 
447 	err = qdisc_class_hash_init(&q->clhash);
448 	if (err < 0)
449 		return err;
450 	INIT_LIST_HEAD(&q->active);
451 	return 0;
452 }
453 
454 static void drr_reset_qdisc(struct Qdisc *sch)
455 {
456 	struct drr_sched *q = qdisc_priv(sch);
457 	struct drr_class *cl;
458 	unsigned int i;
459 
460 	for (i = 0; i < q->clhash.hashsize; i++) {
461 		hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
462 			if (cl->qdisc->q.qlen)
463 				list_del(&cl->alist);
464 			qdisc_reset(cl->qdisc);
465 		}
466 	}
467 	sch->q.qlen = 0;
468 }
469 
470 static void drr_destroy_qdisc(struct Qdisc *sch)
471 {
472 	struct drr_sched *q = qdisc_priv(sch);
473 	struct drr_class *cl;
474 	struct hlist_node *next;
475 	unsigned int i;
476 
477 	tcf_destroy_chain(&q->filter_list);
478 
479 	for (i = 0; i < q->clhash.hashsize; i++) {
480 		hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],
481 					  common.hnode)
482 			drr_destroy_class(sch, cl);
483 	}
484 	qdisc_class_hash_destroy(&q->clhash);
485 }
486 
487 static const struct Qdisc_class_ops drr_class_ops = {
488 	.change		= drr_change_class,
489 	.delete		= drr_delete_class,
490 	.get		= drr_get_class,
491 	.put		= drr_put_class,
492 	.tcf_chain	= drr_tcf_chain,
493 	.bind_tcf	= drr_bind_tcf,
494 	.unbind_tcf	= drr_unbind_tcf,
495 	.graft		= drr_graft_class,
496 	.leaf		= drr_class_leaf,
497 	.qlen_notify	= drr_qlen_notify,
498 	.dump		= drr_dump_class,
499 	.dump_stats	= drr_dump_class_stats,
500 	.walk		= drr_walk,
501 };
502 
503 static struct Qdisc_ops drr_qdisc_ops __read_mostly = {
504 	.cl_ops		= &drr_class_ops,
505 	.id		= "drr",
506 	.priv_size	= sizeof(struct drr_sched),
507 	.enqueue	= drr_enqueue,
508 	.dequeue	= drr_dequeue,
509 	.peek		= qdisc_peek_dequeued,
510 	.drop		= drr_drop,
511 	.init		= drr_init_qdisc,
512 	.reset		= drr_reset_qdisc,
513 	.destroy	= drr_destroy_qdisc,
514 	.owner		= THIS_MODULE,
515 };
516 
517 static int __init drr_init(void)
518 {
519 	return register_qdisc(&drr_qdisc_ops);
520 }
521 
522 static void __exit drr_exit(void)
523 {
524 	unregister_qdisc(&drr_qdisc_ops);
525 }
526 
527 module_init(drr_init);
528 module_exit(drr_exit);
529 MODULE_LICENSE("GPL");
530