xref: /linux/net/sched/sch_drr.c (revision 95db3b255fde4e830e5f8cc011eb404023f669d4) 
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 	unsigned int backlog = cl->qdisc->qstats.backlog;
57 
58 	qdisc_reset(cl->qdisc);
59 	qdisc_tree_reduce_backlog(cl->qdisc, len, backlog);
60 }
61 
62 static const struct nla_policy drr_policy[TCA_DRR_MAX + 1] = {
63 	[TCA_DRR_QUANTUM]	= { .type = NLA_U32 },
64 };
65 
66 static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
67 			    struct nlattr **tca, unsigned long *arg)
68 {
69 	struct drr_sched *q = qdisc_priv(sch);
70 	struct drr_class *cl = (struct drr_class *)*arg;
71 	struct nlattr *opt = tca[TCA_OPTIONS];
72 	struct nlattr *tb[TCA_DRR_MAX + 1];
73 	u32 quantum;
74 	int err;
75 
76 	if (!opt)
77 		return -EINVAL;
78 
79 	err = nla_parse_nested(tb, TCA_DRR_MAX, opt, drr_policy);
80 	if (err < 0)
81 		return err;
82 
83 	if (tb[TCA_DRR_QUANTUM]) {
84 		quantum = nla_get_u32(tb[TCA_DRR_QUANTUM]);
85 		if (quantum == 0)
86 			return -EINVAL;
87 	} else
88 		quantum = psched_mtu(qdisc_dev(sch));
89 
90 	if (cl != NULL) {
91 		if (tca[TCA_RATE]) {
92 			err = gen_replace_estimator(&cl->bstats, NULL,
93 						    &cl->rate_est,
94 						    qdisc_root_sleeping_lock(sch),
95 						    tca[TCA_RATE]);
96 			if (err)
97 				return err;
98 		}
99 
100 		sch_tree_lock(sch);
101 		if (tb[TCA_DRR_QUANTUM])
102 			cl->quantum = quantum;
103 		sch_tree_unlock(sch);
104 
105 		return 0;
106 	}
107 
108 	cl = kzalloc(sizeof(struct drr_class), GFP_KERNEL);
109 	if (cl == NULL)
110 		return -ENOBUFS;
111 
112 	cl->refcnt	   = 1;
113 	cl->common.classid = classid;
114 	cl->quantum	   = quantum;
115 	cl->qdisc	   = qdisc_create_dflt(sch->dev_queue,
116 					       &pfifo_qdisc_ops, classid);
117 	if (cl->qdisc == NULL)
118 		cl->qdisc = &noop_qdisc;
119 
120 	if (tca[TCA_RATE]) {
121 		err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est,
122 					    qdisc_root_sleeping_lock(sch),
123 					    tca[TCA_RATE]);
124 		if (err) {
125 			qdisc_destroy(cl->qdisc);
126 			kfree(cl);
127 			return err;
128 		}
129 	}
130 
131 	sch_tree_lock(sch);
132 	qdisc_class_hash_insert(&q->clhash, &cl->common);
133 	sch_tree_unlock(sch);
134 
135 	qdisc_class_hash_grow(sch, &q->clhash);
136 
137 	*arg = (unsigned long)cl;
138 	return 0;
139 }
140 
141 static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl)
142 {
143 	gen_kill_estimator(&cl->bstats, &cl->rate_est);
144 	qdisc_destroy(cl->qdisc);
145 	kfree(cl);
146 }
147 
148 static int drr_delete_class(struct Qdisc *sch, unsigned long arg)
149 {
150 	struct drr_sched *q = qdisc_priv(sch);
151 	struct drr_class *cl = (struct drr_class *)arg;
152 
153 	if (cl->filter_cnt > 0)
154 		return -EBUSY;
155 
156 	sch_tree_lock(sch);
157 
158 	drr_purge_queue(cl);
159 	qdisc_class_hash_remove(&q->clhash, &cl->common);
160 
161 	BUG_ON(--cl->refcnt == 0);
162 	/*
163 	 * This shouldn't happen: we "hold" one cops->get() when called
164 	 * from tc_ctl_tclass; the destroy method is done from cops->put().
165 	 */
166 
167 	sch_tree_unlock(sch);
168 	return 0;
169 }
170 
171 static unsigned long drr_get_class(struct Qdisc *sch, u32 classid)
172 {
173 	struct drr_class *cl = drr_find_class(sch, classid);
174 
175 	if (cl != NULL)
176 		cl->refcnt++;
177 
178 	return (unsigned long)cl;
179 }
180 
181 static void drr_put_class(struct Qdisc *sch, unsigned long arg)
182 {
183 	struct drr_class *cl = (struct drr_class *)arg;
184 
185 	if (--cl->refcnt == 0)
186 		drr_destroy_class(sch, cl);
187 }
188 
189 static struct tcf_proto __rcu **drr_tcf_chain(struct Qdisc *sch,
190 					      unsigned long cl)
191 {
192 	struct drr_sched *q = qdisc_priv(sch);
193 
194 	if (cl)
195 		return NULL;
196 
197 	return &q->filter_list;
198 }
199 
200 static unsigned long drr_bind_tcf(struct Qdisc *sch, unsigned long parent,
201 				  u32 classid)
202 {
203 	struct drr_class *cl = drr_find_class(sch, classid);
204 
205 	if (cl != NULL)
206 		cl->filter_cnt++;
207 
208 	return (unsigned long)cl;
209 }
210 
211 static void drr_unbind_tcf(struct Qdisc *sch, unsigned long arg)
212 {
213 	struct drr_class *cl = (struct drr_class *)arg;
214 
215 	cl->filter_cnt--;
216 }
217 
218 static int drr_graft_class(struct Qdisc *sch, unsigned long arg,
219 			   struct Qdisc *new, struct Qdisc **old)
220 {
221 	struct drr_class *cl = (struct drr_class *)arg;
222 
223 	if (new == NULL) {
224 		new = qdisc_create_dflt(sch->dev_queue,
225 					&pfifo_qdisc_ops, cl->common.classid);
226 		if (new == NULL)
227 			new = &noop_qdisc;
228 	}
229 
230 	*old = qdisc_replace(sch, new, &cl->qdisc);
231 	return 0;
232 }
233 
234 static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg)
235 {
236 	struct drr_class *cl = (struct drr_class *)arg;
237 
238 	return cl->qdisc;
239 }
240 
241 static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg)
242 {
243 	struct drr_class *cl = (struct drr_class *)arg;
244 
245 	if (cl->qdisc->q.qlen == 0)
246 		list_del(&cl->alist);
247 }
248 
249 static int drr_dump_class(struct Qdisc *sch, unsigned long arg,
250 			  struct sk_buff *skb, struct tcmsg *tcm)
251 {
252 	struct drr_class *cl = (struct drr_class *)arg;
253 	struct nlattr *nest;
254 
255 	tcm->tcm_parent	= TC_H_ROOT;
256 	tcm->tcm_handle	= cl->common.classid;
257 	tcm->tcm_info	= cl->qdisc->handle;
258 
259 	nest = nla_nest_start(skb, TCA_OPTIONS);
260 	if (nest == NULL)
261 		goto nla_put_failure;
262 	if (nla_put_u32(skb, TCA_DRR_QUANTUM, cl->quantum))
263 		goto nla_put_failure;
264 	return nla_nest_end(skb, nest);
265 
266 nla_put_failure:
267 	nla_nest_cancel(skb, nest);
268 	return -EMSGSIZE;
269 }
270 
271 static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg,
272 				struct gnet_dump *d)
273 {
274 	struct drr_class *cl = (struct drr_class *)arg;
275 	__u32 qlen = cl->qdisc->q.qlen;
276 	struct tc_drr_stats xstats;
277 
278 	memset(&xstats, 0, sizeof(xstats));
279 	if (qlen)
280 		xstats.deficit = cl->deficit;
281 
282 	if (gnet_stats_copy_basic(d, NULL, &cl->bstats) < 0 ||
283 	    gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 ||
284 	    gnet_stats_copy_queue(d, NULL, &cl->qdisc->qstats, qlen) < 0)
285 		return -1;
286 
287 	return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
288 }
289 
290 static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg)
291 {
292 	struct drr_sched *q = qdisc_priv(sch);
293 	struct drr_class *cl;
294 	unsigned int i;
295 
296 	if (arg->stop)
297 		return;
298 
299 	for (i = 0; i < q->clhash.hashsize; i++) {
300 		hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
301 			if (arg->count < arg->skip) {
302 				arg->count++;
303 				continue;
304 			}
305 			if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
306 				arg->stop = 1;
307 				return;
308 			}
309 			arg->count++;
310 		}
311 	}
312 }
313 
314 static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch,
315 				      int *qerr)
316 {
317 	struct drr_sched *q = qdisc_priv(sch);
318 	struct drr_class *cl;
319 	struct tcf_result res;
320 	struct tcf_proto *fl;
321 	int result;
322 
323 	if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
324 		cl = drr_find_class(sch, skb->priority);
325 		if (cl != NULL)
326 			return cl;
327 	}
328 
329 	*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
330 	fl = rcu_dereference_bh(q->filter_list);
331 	result = tc_classify(skb, fl, &res, false);
332 	if (result >= 0) {
333 #ifdef CONFIG_NET_CLS_ACT
334 		switch (result) {
335 		case TC_ACT_QUEUED:
336 		case TC_ACT_STOLEN:
337 			*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
338 		case TC_ACT_SHOT:
339 			return NULL;
340 		}
341 #endif
342 		cl = (struct drr_class *)res.class;
343 		if (cl == NULL)
344 			cl = drr_find_class(sch, res.classid);
345 		return cl;
346 	}
347 	return NULL;
348 }
349 
350 static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch)
351 {
352 	struct drr_sched *q = qdisc_priv(sch);
353 	struct drr_class *cl;
354 	int err = 0;
355 
356 	cl = drr_classify(skb, sch, &err);
357 	if (cl == NULL) {
358 		if (err & __NET_XMIT_BYPASS)
359 			qdisc_qstats_drop(sch);
360 		kfree_skb(skb);
361 		return err;
362 	}
363 
364 	err = qdisc_enqueue(skb, cl->qdisc);
365 	if (unlikely(err != NET_XMIT_SUCCESS)) {
366 		if (net_xmit_drop_count(err)) {
367 			cl->qstats.drops++;
368 			qdisc_qstats_drop(sch);
369 		}
370 		return err;
371 	}
372 
373 	if (cl->qdisc->q.qlen == 1) {
374 		list_add_tail(&cl->alist, &q->active);
375 		cl->deficit = cl->quantum;
376 	}
377 
378 	qdisc_qstats_backlog_inc(sch, skb);
379 	sch->q.qlen++;
380 	return err;
381 }
382 
383 static struct sk_buff *drr_dequeue(struct Qdisc *sch)
384 {
385 	struct drr_sched *q = qdisc_priv(sch);
386 	struct drr_class *cl;
387 	struct sk_buff *skb;
388 	unsigned int len;
389 
390 	if (list_empty(&q->active))
391 		goto out;
392 	while (1) {
393 		cl = list_first_entry(&q->active, struct drr_class, alist);
394 		skb = cl->qdisc->ops->peek(cl->qdisc);
395 		if (skb == NULL) {
396 			qdisc_warn_nonwc(__func__, cl->qdisc);
397 			goto out;
398 		}
399 
400 		len = qdisc_pkt_len(skb);
401 		if (len <= cl->deficit) {
402 			cl->deficit -= len;
403 			skb = qdisc_dequeue_peeked(cl->qdisc);
404 			if (unlikely(skb == NULL))
405 				goto out;
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 			qdisc_qstats_backlog_dec(sch, skb);
412 			sch->q.qlen--;
413 			return skb;
414 		}
415 
416 		cl->deficit += cl->quantum;
417 		list_move_tail(&cl->alist, &q->active);
418 	}
419 out:
420 	return NULL;
421 }
422 
423 static unsigned int drr_drop(struct Qdisc *sch)
424 {
425 	struct drr_sched *q = qdisc_priv(sch);
426 	struct drr_class *cl;
427 	unsigned int len;
428 
429 	list_for_each_entry(cl, &q->active, alist) {
430 		if (cl->qdisc->ops->drop) {
431 			len = cl->qdisc->ops->drop(cl->qdisc);
432 			if (len > 0) {
433 				sch->qstats.backlog -= len;
434 				sch->q.qlen--;
435 				if (cl->qdisc->q.qlen == 0)
436 					list_del(&cl->alist);
437 				return len;
438 			}
439 		}
440 	}
441 	return 0;
442 }
443 
444 static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
445 {
446 	struct drr_sched *q = qdisc_priv(sch);
447 	int err;
448 
449 	err = qdisc_class_hash_init(&q->clhash);
450 	if (err < 0)
451 		return err;
452 	INIT_LIST_HEAD(&q->active);
453 	return 0;
454 }
455 
456 static void drr_reset_qdisc(struct Qdisc *sch)
457 {
458 	struct drr_sched *q = qdisc_priv(sch);
459 	struct drr_class *cl;
460 	unsigned int i;
461 
462 	for (i = 0; i < q->clhash.hashsize; i++) {
463 		hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
464 			if (cl->qdisc->q.qlen)
465 				list_del(&cl->alist);
466 			qdisc_reset(cl->qdisc);
467 		}
468 	}
469 	sch->qstats.backlog = 0;
470 	sch->q.qlen = 0;
471 }
472 
473 static void drr_destroy_qdisc(struct Qdisc *sch)
474 {
475 	struct drr_sched *q = qdisc_priv(sch);
476 	struct drr_class *cl;
477 	struct hlist_node *next;
478 	unsigned int i;
479 
480 	tcf_destroy_chain(&q->filter_list);
481 
482 	for (i = 0; i < q->clhash.hashsize; i++) {
483 		hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],
484 					  common.hnode)
485 			drr_destroy_class(sch, cl);
486 	}
487 	qdisc_class_hash_destroy(&q->clhash);
488 }
489 
490 static const struct Qdisc_class_ops drr_class_ops = {
491 	.change		= drr_change_class,
492 	.delete		= drr_delete_class,
493 	.get		= drr_get_class,
494 	.put		= drr_put_class,
495 	.tcf_chain	= drr_tcf_chain,
496 	.bind_tcf	= drr_bind_tcf,
497 	.unbind_tcf	= drr_unbind_tcf,
498 	.graft		= drr_graft_class,
499 	.leaf		= drr_class_leaf,
500 	.qlen_notify	= drr_qlen_notify,
501 	.dump		= drr_dump_class,
502 	.dump_stats	= drr_dump_class_stats,
503 	.walk		= drr_walk,
504 };
505 
506 static struct Qdisc_ops drr_qdisc_ops __read_mostly = {
507 	.cl_ops		= &drr_class_ops,
508 	.id		= "drr",
509 	.priv_size	= sizeof(struct drr_sched),
510 	.enqueue	= drr_enqueue,
511 	.dequeue	= drr_dequeue,
512 	.peek		= qdisc_peek_dequeued,
513 	.drop		= drr_drop,
514 	.init		= drr_init_qdisc,
515 	.reset		= drr_reset_qdisc,
516 	.destroy	= drr_destroy_qdisc,
517 	.owner		= THIS_MODULE,
518 };
519 
520 static int __init drr_init(void)
521 {
522 	return register_qdisc(&drr_qdisc_ops);
523 }
524 
525 static void __exit drr_exit(void)
526 {
527 	unregister_qdisc(&drr_qdisc_ops);
528 }
529 
530 module_init(drr_init);
531 module_exit(drr_exit);
532 MODULE_LICENSE("GPL");
533