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sch_drr.c
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1 /*
2  * net/sched/sch_drr.c Deficit Round Robin scheduler
3  *
4  * Copyright (c) 2008 Patrick McHardy <[email protected]>
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_est 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 *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, &cl->rate_est,
92  qdisc_root_sleeping_lock(sch),
93  tca[TCA_RATE]);
94  if (err)
95  return err;
96  }
97 
98  sch_tree_lock(sch);
99  if (tb[TCA_DRR_QUANTUM])
100  cl->quantum = quantum;
101  sch_tree_unlock(sch);
102 
103  return 0;
104  }
105 
106  cl = kzalloc(sizeof(struct drr_class), GFP_KERNEL);
107  if (cl == NULL)
108  return -ENOBUFS;
109 
110  cl->refcnt = 1;
111  cl->common.classid = classid;
112  cl->quantum = quantum;
113  cl->qdisc = qdisc_create_dflt(sch->dev_queue,
114  &pfifo_qdisc_ops, classid);
115  if (cl->qdisc == NULL)
116  cl->qdisc = &noop_qdisc;
117 
118  if (tca[TCA_RATE]) {
119  err = gen_replace_estimator(&cl->bstats, &cl->rate_est,
120  qdisc_root_sleeping_lock(sch),
121  tca[TCA_RATE]);
122  if (err) {
123  qdisc_destroy(cl->qdisc);
124  kfree(cl);
125  return err;
126  }
127  }
128 
129  sch_tree_lock(sch);
130  qdisc_class_hash_insert(&q->clhash, &cl->common);
131  sch_tree_unlock(sch);
132 
133  qdisc_class_hash_grow(sch, &q->clhash);
134 
135  *arg = (unsigned long)cl;
136  return 0;
137 }
138 
139 static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl)
140 {
141  gen_kill_estimator(&cl->bstats, &cl->rate_est);
142  qdisc_destroy(cl->qdisc);
143  kfree(cl);
144 }
145 
146 static int drr_delete_class(struct Qdisc *sch, unsigned long arg)
147 {
148  struct drr_sched *q = qdisc_priv(sch);
149  struct drr_class *cl = (struct drr_class *)arg;
150 
151  if (cl->filter_cnt > 0)
152  return -EBUSY;
153 
154  sch_tree_lock(sch);
155 
156  drr_purge_queue(cl);
157  qdisc_class_hash_remove(&q->clhash, &cl->common);
158 
159  BUG_ON(--cl->refcnt == 0);
160  /*
161  * This shouldn't happen: we "hold" one cops->get() when called
162  * from tc_ctl_tclass; the destroy method is done from cops->put().
163  */
164 
165  sch_tree_unlock(sch);
166  return 0;
167 }
168 
169 static unsigned long drr_get_class(struct Qdisc *sch, u32 classid)
170 {
171  struct drr_class *cl = drr_find_class(sch, classid);
172 
173  if (cl != NULL)
174  cl->refcnt++;
175 
176  return (unsigned long)cl;
177 }
178 
179 static void drr_put_class(struct Qdisc *sch, unsigned long arg)
180 {
181  struct drr_class *cl = (struct drr_class *)arg;
182 
183  if (--cl->refcnt == 0)
184  drr_destroy_class(sch, cl);
185 }
186 
187 static struct tcf_proto **drr_tcf_chain(struct Qdisc *sch, unsigned long cl)
188 {
189  struct drr_sched *q = qdisc_priv(sch);
190 
191  if (cl)
192  return NULL;
193 
194  return &q->filter_list;
195 }
196 
197 static unsigned long drr_bind_tcf(struct Qdisc *sch, unsigned long parent,
198  u32 classid)
199 {
200  struct drr_class *cl = drr_find_class(sch, classid);
201 
202  if (cl != NULL)
203  cl->filter_cnt++;
204 
205  return (unsigned long)cl;
206 }
207 
208 static void drr_unbind_tcf(struct Qdisc *sch, unsigned long arg)
209 {
210  struct drr_class *cl = (struct drr_class *)arg;
211 
212  cl->filter_cnt--;
213 }
214 
215 static int drr_graft_class(struct Qdisc *sch, unsigned long arg,
216  struct Qdisc *new, struct Qdisc **old)
217 {
218  struct drr_class *cl = (struct drr_class *)arg;
219 
220  if (new == NULL) {
221  new = qdisc_create_dflt(sch->dev_queue,
222  &pfifo_qdisc_ops, cl->common.classid);
223  if (new == NULL)
224  new = &noop_qdisc;
225  }
226 
227  sch_tree_lock(sch);
228  drr_purge_queue(cl);
229  *old = cl->qdisc;
230  cl->qdisc = new;
231  sch_tree_unlock(sch);
232  return 0;
233 }
234 
235 static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg)
236 {
237  struct drr_class *cl = (struct drr_class *)arg;
238 
239  return cl->qdisc;
240 }
241 
242 static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg)
243 {
244  struct drr_class *cl = (struct drr_class *)arg;
245 
246  if (cl->qdisc->q.qlen == 0)
247  list_del(&cl->alist);
248 }
249 
250 static int drr_dump_class(struct Qdisc *sch, unsigned long arg,
251  struct sk_buff *skb, struct tcmsg *tcm)
252 {
253  struct drr_class *cl = (struct drr_class *)arg;
254  struct nlattr *nest;
255 
256  tcm->tcm_parent = TC_H_ROOT;
257  tcm->tcm_handle = cl->common.classid;
258  tcm->tcm_info = cl->qdisc->handle;
259 
260  nest = nla_nest_start(skb, TCA_OPTIONS);
261  if (nest == NULL)
262  goto nla_put_failure;
263  if (nla_put_u32(skb, TCA_DRR_QUANTUM, cl->quantum))
264  goto nla_put_failure;
265  return nla_nest_end(skb, nest);
266 
267 nla_put_failure:
268  nla_nest_cancel(skb, nest);
269  return -EMSGSIZE;
270 }
271 
272 static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg,
273  struct gnet_dump *d)
274 {
275  struct drr_class *cl = (struct drr_class *)arg;
276  struct tc_drr_stats xstats;
277 
278  memset(&xstats, 0, sizeof(xstats));
279  if (cl->qdisc->q.qlen) {
280  xstats.deficit = cl->deficit;
281  cl->qdisc->qstats.qlen = cl->qdisc->q.qlen;
282  }
283 
284  if (gnet_stats_copy_basic(d, &cl->bstats) < 0 ||
285  gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 ||
286  gnet_stats_copy_queue(d, &cl->qdisc->qstats) < 0)
287  return -1;
288 
289  return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
290 }
291 
292 static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg)
293 {
294  struct drr_sched *q = qdisc_priv(sch);
295  struct drr_class *cl;
296  struct hlist_node *n;
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, n, &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  int result;
324 
325  if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
326  cl = drr_find_class(sch, skb->priority);
327  if (cl != NULL)
328  return cl;
329  }
330 
331  *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
332  result = tc_classify(skb, q->filter_list, &res);
333  if (result >= 0) {
334 #ifdef CONFIG_NET_CLS_ACT
335  switch (result) {
336  case TC_ACT_QUEUED:
337  case TC_ACT_STOLEN:
338  *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
339  case TC_ACT_SHOT:
340  return NULL;
341  }
342 #endif
343  cl = (struct drr_class *)res.class;
344  if (cl == NULL)
345  cl = drr_find_class(sch, res.classid);
346  return cl;
347  }
348  return NULL;
349 }
350 
351 static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch)
352 {
353  struct drr_sched *q = qdisc_priv(sch);
354  struct drr_class *cl;
355  int err = 0;
356 
357  cl = drr_classify(skb, sch, &err);
358  if (cl == NULL) {
359  if (err & __NET_XMIT_BYPASS)
360  sch->qstats.drops++;
361  kfree_skb(skb);
362  return err;
363  }
364 
365  err = qdisc_enqueue(skb, cl->qdisc);
366  if (unlikely(err != NET_XMIT_SUCCESS)) {
367  if (net_xmit_drop_count(err)) {
368  cl->qstats.drops++;
369  sch->qstats.drops++;
370  }
371  return err;
372  }
373 
374  if (cl->qdisc->q.qlen == 1) {
375  list_add_tail(&cl->alist, &q->active);
376  cl->deficit = cl->quantum;
377  }
378 
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  goto out;
397 
398  len = qdisc_pkt_len(skb);
399  if (len <= cl->deficit) {
400  cl->deficit -= len;
401  skb = qdisc_dequeue_peeked(cl->qdisc);
402  if (cl->qdisc->q.qlen == 0)
403  list_del(&cl->alist);
404 
405  bstats_update(&cl->bstats, skb);
406  qdisc_bstats_update(sch, skb);
407  sch->q.qlen--;
408  return skb;
409  }
410 
411  cl->deficit += cl->quantum;
412  list_move_tail(&cl->alist, &q->active);
413  }
414 out:
415  return NULL;
416 }
417 
418 static unsigned int drr_drop(struct Qdisc *sch)
419 {
420  struct drr_sched *q = qdisc_priv(sch);
421  struct drr_class *cl;
422  unsigned int len;
423 
424  list_for_each_entry(cl, &q->active, alist) {
425  if (cl->qdisc->ops->drop) {
426  len = cl->qdisc->ops->drop(cl->qdisc);
427  if (len > 0) {
428  sch->q.qlen--;
429  if (cl->qdisc->q.qlen == 0)
430  list_del(&cl->alist);
431  return len;
432  }
433  }
434  }
435  return 0;
436 }
437 
438 static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
439 {
440  struct drr_sched *q = qdisc_priv(sch);
441  int err;
442 
443  err = qdisc_class_hash_init(&q->clhash);
444  if (err < 0)
445  return err;
446  INIT_LIST_HEAD(&q->active);
447  return 0;
448 }
449 
450 static void drr_reset_qdisc(struct Qdisc *sch)
451 {
452  struct drr_sched *q = qdisc_priv(sch);
453  struct drr_class *cl;
454  struct hlist_node *n;
455  unsigned int i;
456 
457  for (i = 0; i < q->clhash.hashsize; i++) {
458  hlist_for_each_entry(cl, n, &q->clhash.hash[i], common.hnode) {
459  if (cl->qdisc->q.qlen)
460  list_del(&cl->alist);
461  qdisc_reset(cl->qdisc);
462  }
463  }
464  sch->q.qlen = 0;
465 }
466 
467 static void drr_destroy_qdisc(struct Qdisc *sch)
468 {
469  struct drr_sched *q = qdisc_priv(sch);
470  struct drr_class *cl;
471  struct hlist_node *n, *next;
472  unsigned int i;
473 
474  tcf_destroy_chain(&q->filter_list);
475 
476  for (i = 0; i < q->clhash.hashsize; i++) {
477  hlist_for_each_entry_safe(cl, n, next, &q->clhash.hash[i],
478  common.hnode)
479  drr_destroy_class(sch, cl);
480  }
481  qdisc_class_hash_destroy(&q->clhash);
482 }
483 
484 static const struct Qdisc_class_ops drr_class_ops = {
485  .change = drr_change_class,
486  .delete = drr_delete_class,
487  .get = drr_get_class,
488  .put = drr_put_class,
489  .tcf_chain = drr_tcf_chain,
490  .bind_tcf = drr_bind_tcf,
491  .unbind_tcf = drr_unbind_tcf,
492  .graft = drr_graft_class,
493  .leaf = drr_class_leaf,
494  .qlen_notify = drr_qlen_notify,
495  .dump = drr_dump_class,
496  .dump_stats = drr_dump_class_stats,
497  .walk = drr_walk,
498 };
499 
500 static struct Qdisc_ops drr_qdisc_ops __read_mostly = {
501  .cl_ops = &drr_class_ops,
502  .id = "drr",
503  .priv_size = sizeof(struct drr_sched),
504  .enqueue = drr_enqueue,
505  .dequeue = drr_dequeue,
506  .peek = qdisc_peek_dequeued,
507  .drop = drr_drop,
508  .init = drr_init_qdisc,
509  .reset = drr_reset_qdisc,
510  .destroy = drr_destroy_qdisc,
511  .owner = THIS_MODULE,
512 };
513 
514 static int __init drr_init(void)
515 {
516  return register_qdisc(&drr_qdisc_ops);
517 }
518 
519 static void __exit drr_exit(void)
520 {
521  unregister_qdisc(&drr_qdisc_ops);
522 }
523 
524 module_init(drr_init);
525 module_exit(drr_exit);
526 MODULE_LICENSE("GPL");
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