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Linux/net/sched/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 <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_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;
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");
527 

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