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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                    filter_cnt;
 24 
 25         struct gnet_stats_basic_packed          bstats;
 26         struct gnet_stats_queue         qstats;
 27         struct net_rate_estimator __rcu *rate_est;
 28         struct list_head                alist;
 29         struct Qdisc                    *qdisc;
 30 
 31         u32                             quantum;
 32         u32                             deficit;
 33 };
 34 
 35 struct drr_sched {
 36         struct list_head                active;
 37         struct tcf_proto __rcu          *filter_list;
 38         struct tcf_block                *block;
 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                             struct netlink_ext_ack *extack)
 69 {
 70         struct drr_sched *q = qdisc_priv(sch);
 71         struct drr_class *cl = (struct drr_class *)*arg;
 72         struct nlattr *opt = tca[TCA_OPTIONS];
 73         struct nlattr *tb[TCA_DRR_MAX + 1];
 74         u32 quantum;
 75         int err;
 76 
 77         if (!opt) {
 78                 NL_SET_ERR_MSG(extack, "DRR options are required for this operation");
 79                 return -EINVAL;
 80         }
 81 
 82         err = nla_parse_nested(tb, TCA_DRR_MAX, opt, drr_policy, extack);
 83         if (err < 0)
 84                 return err;
 85 
 86         if (tb[TCA_DRR_QUANTUM]) {
 87                 quantum = nla_get_u32(tb[TCA_DRR_QUANTUM]);
 88                 if (quantum == 0) {
 89                         NL_SET_ERR_MSG(extack, "Specified DRR quantum cannot be zero");
 90                         return -EINVAL;
 91                 }
 92         } else
 93                 quantum = psched_mtu(qdisc_dev(sch));
 94 
 95         if (cl != NULL) {
 96                 if (tca[TCA_RATE]) {
 97                         err = gen_replace_estimator(&cl->bstats, NULL,
 98                                                     &cl->rate_est,
 99                                                     NULL,
100                                                     qdisc_root_sleeping_running(sch),
101                                                     tca[TCA_RATE]);
102                         if (err) {
103                                 NL_SET_ERR_MSG(extack, "Failed to replace estimator");
104                                 return err;
105                         }
106                 }
107 
108                 sch_tree_lock(sch);
109                 if (tb[TCA_DRR_QUANTUM])
110                         cl->quantum = quantum;
111                 sch_tree_unlock(sch);
112 
113                 return 0;
114         }
115 
116         cl = kzalloc(sizeof(struct drr_class), GFP_KERNEL);
117         if (cl == NULL)
118                 return -ENOBUFS;
119 
120         cl->common.classid = classid;
121         cl->quantum        = quantum;
122         cl->qdisc          = qdisc_create_dflt(sch->dev_queue,
123                                                &pfifo_qdisc_ops, classid,
124                                                NULL);
125         if (cl->qdisc == NULL)
126                 cl->qdisc = &noop_qdisc;
127         else
128                 qdisc_hash_add(cl->qdisc, true);
129 
130         if (tca[TCA_RATE]) {
131                 err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est,
132                                             NULL,
133                                             qdisc_root_sleeping_running(sch),
134                                             tca[TCA_RATE]);
135                 if (err) {
136                         NL_SET_ERR_MSG(extack, "Failed to replace estimator");
137                         qdisc_put(cl->qdisc);
138                         kfree(cl);
139                         return err;
140                 }
141         }
142 
143         sch_tree_lock(sch);
144         qdisc_class_hash_insert(&q->clhash, &cl->common);
145         sch_tree_unlock(sch);
146 
147         qdisc_class_hash_grow(sch, &q->clhash);
148 
149         *arg = (unsigned long)cl;
150         return 0;
151 }
152 
153 static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl)
154 {
155         gen_kill_estimator(&cl->rate_est);
156         qdisc_put(cl->qdisc);
157         kfree(cl);
158 }
159 
160 static int drr_delete_class(struct Qdisc *sch, unsigned long arg)
161 {
162         struct drr_sched *q = qdisc_priv(sch);
163         struct drr_class *cl = (struct drr_class *)arg;
164 
165         if (cl->filter_cnt > 0)
166                 return -EBUSY;
167 
168         sch_tree_lock(sch);
169 
170         drr_purge_queue(cl);
171         qdisc_class_hash_remove(&q->clhash, &cl->common);
172 
173         sch_tree_unlock(sch);
174 
175         drr_destroy_class(sch, cl);
176         return 0;
177 }
178 
179 static unsigned long drr_search_class(struct Qdisc *sch, u32 classid)
180 {
181         return (unsigned long)drr_find_class(sch, classid);
182 }
183 
184 static struct tcf_block *drr_tcf_block(struct Qdisc *sch, unsigned long cl,
185                                        struct netlink_ext_ack *extack)
186 {
187         struct drr_sched *q = qdisc_priv(sch);
188 
189         if (cl) {
190                 NL_SET_ERR_MSG(extack, "DRR classid must be zero");
191                 return NULL;
192         }
193 
194         return q->block;
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                            struct netlink_ext_ack *extack)
218 {
219         struct drr_class *cl = (struct drr_class *)arg;
220 
221         if (new == NULL) {
222                 new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
223                                         cl->common.classid, NULL);
224                 if (new == NULL)
225                         new = &noop_qdisc;
226         }
227 
228         *old = qdisc_replace(sch, new, &cl->qdisc);
229         return 0;
230 }
231 
232 static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg)
233 {
234         struct drr_class *cl = (struct drr_class *)arg;
235 
236         return cl->qdisc;
237 }
238 
239 static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg)
240 {
241         struct drr_class *cl = (struct drr_class *)arg;
242 
243         list_del(&cl->alist);
244 }
245 
246 static int drr_dump_class(struct Qdisc *sch, unsigned long arg,
247                           struct sk_buff *skb, struct tcmsg *tcm)
248 {
249         struct drr_class *cl = (struct drr_class *)arg;
250         struct nlattr *nest;
251 
252         tcm->tcm_parent = TC_H_ROOT;
253         tcm->tcm_handle = cl->common.classid;
254         tcm->tcm_info   = cl->qdisc->handle;
255 
256         nest = nla_nest_start(skb, TCA_OPTIONS);
257         if (nest == NULL)
258                 goto nla_put_failure;
259         if (nla_put_u32(skb, TCA_DRR_QUANTUM, cl->quantum))
260                 goto nla_put_failure;
261         return nla_nest_end(skb, nest);
262 
263 nla_put_failure:
264         nla_nest_cancel(skb, nest);
265         return -EMSGSIZE;
266 }
267 
268 static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg,
269                                 struct gnet_dump *d)
270 {
271         struct drr_class *cl = (struct drr_class *)arg;
272         __u32 qlen = cl->qdisc->q.qlen;
273         struct tc_drr_stats xstats;
274 
275         memset(&xstats, 0, sizeof(xstats));
276         if (qlen)
277                 xstats.deficit = cl->deficit;
278 
279         if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
280                                   d, NULL, &cl->bstats) < 0 ||
281             gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
282             gnet_stats_copy_queue(d, NULL, &cl->qdisc->qstats, qlen) < 0)
283                 return -1;
284 
285         return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
286 }
287 
288 static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg)
289 {
290         struct drr_sched *q = qdisc_priv(sch);
291         struct drr_class *cl;
292         unsigned int i;
293 
294         if (arg->stop)
295                 return;
296 
297         for (i = 0; i < q->clhash.hashsize; i++) {
298                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
299                         if (arg->count < arg->skip) {
300                                 arg->count++;
301                                 continue;
302                         }
303                         if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
304                                 arg->stop = 1;
305                                 return;
306                         }
307                         arg->count++;
308                 }
309         }
310 }
311 
312 static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch,
313                                       int *qerr)
314 {
315         struct drr_sched *q = qdisc_priv(sch);
316         struct drr_class *cl;
317         struct tcf_result res;
318         struct tcf_proto *fl;
319         int result;
320 
321         if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
322                 cl = drr_find_class(sch, skb->priority);
323                 if (cl != NULL)
324                         return cl;
325         }
326 
327         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
328         fl = rcu_dereference_bh(q->filter_list);
329         result = tcf_classify(skb, fl, &res, false);
330         if (result >= 0) {
331 #ifdef CONFIG_NET_CLS_ACT
332                 switch (result) {
333                 case TC_ACT_QUEUED:
334                 case TC_ACT_STOLEN:
335                 case TC_ACT_TRAP:
336                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
337                         /* fall through */
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                        struct sk_buff **to_free)
352 {
353         unsigned int len = qdisc_pkt_len(skb);
354         struct drr_sched *q = qdisc_priv(sch);
355         struct drr_class *cl;
356         int err = 0;
357         bool first;
358 
359         cl = drr_classify(skb, sch, &err);
360         if (cl == NULL) {
361                 if (err & __NET_XMIT_BYPASS)
362                         qdisc_qstats_drop(sch);
363                 __qdisc_drop(skb, to_free);
364                 return err;
365         }
366 
367         first = !cl->qdisc->q.qlen;
368         err = qdisc_enqueue(skb, cl->qdisc, to_free);
369         if (unlikely(err != NET_XMIT_SUCCESS)) {
370                 if (net_xmit_drop_count(err)) {
371                         cl->qstats.drops++;
372                         qdisc_qstats_drop(sch);
373                 }
374                 return err;
375         }
376 
377         if (first) {
378                 list_add_tail(&cl->alist, &q->active);
379                 cl->deficit = cl->quantum;
380         }
381 
382         sch->qstats.backlog += len;
383         sch->q.qlen++;
384         return err;
385 }
386 
387 static struct sk_buff *drr_dequeue(struct Qdisc *sch)
388 {
389         struct drr_sched *q = qdisc_priv(sch);
390         struct drr_class *cl;
391         struct sk_buff *skb;
392         unsigned int len;
393 
394         if (list_empty(&q->active))
395                 goto out;
396         while (1) {
397                 cl = list_first_entry(&q->active, struct drr_class, alist);
398                 skb = cl->qdisc->ops->peek(cl->qdisc);
399                 if (skb == NULL) {
400                         qdisc_warn_nonwc(__func__, cl->qdisc);
401                         goto out;
402                 }
403 
404                 len = qdisc_pkt_len(skb);
405                 if (len <= cl->deficit) {
406                         cl->deficit -= len;
407                         skb = qdisc_dequeue_peeked(cl->qdisc);
408                         if (unlikely(skb == NULL))
409                                 goto out;
410                         if (cl->qdisc->q.qlen == 0)
411                                 list_del(&cl->alist);
412 
413                         bstats_update(&cl->bstats, skb);
414                         qdisc_bstats_update(sch, skb);
415                         qdisc_qstats_backlog_dec(sch, skb);
416                         sch->q.qlen--;
417                         return skb;
418                 }
419 
420                 cl->deficit += cl->quantum;
421                 list_move_tail(&cl->alist, &q->active);
422         }
423 out:
424         return NULL;
425 }
426 
427 static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt,
428                           struct netlink_ext_ack *extack)
429 {
430         struct drr_sched *q = qdisc_priv(sch);
431         int err;
432 
433         err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
434         if (err)
435                 return err;
436         err = qdisc_class_hash_init(&q->clhash);
437         if (err < 0)
438                 return err;
439         INIT_LIST_HEAD(&q->active);
440         return 0;
441 }
442 
443 static void drr_reset_qdisc(struct Qdisc *sch)
444 {
445         struct drr_sched *q = qdisc_priv(sch);
446         struct drr_class *cl;
447         unsigned int i;
448 
449         for (i = 0; i < q->clhash.hashsize; i++) {
450                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
451                         if (cl->qdisc->q.qlen)
452                                 list_del(&cl->alist);
453                         qdisc_reset(cl->qdisc);
454                 }
455         }
456         sch->qstats.backlog = 0;
457         sch->q.qlen = 0;
458 }
459 
460 static void drr_destroy_qdisc(struct Qdisc *sch)
461 {
462         struct drr_sched *q = qdisc_priv(sch);
463         struct drr_class *cl;
464         struct hlist_node *next;
465         unsigned int i;
466 
467         tcf_block_put(q->block);
468 
469         for (i = 0; i < q->clhash.hashsize; i++) {
470                 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],
471                                           common.hnode)
472                         drr_destroy_class(sch, cl);
473         }
474         qdisc_class_hash_destroy(&q->clhash);
475 }
476 
477 static const struct Qdisc_class_ops drr_class_ops = {
478         .change         = drr_change_class,
479         .delete         = drr_delete_class,
480         .find           = drr_search_class,
481         .tcf_block      = drr_tcf_block,
482         .bind_tcf       = drr_bind_tcf,
483         .unbind_tcf     = drr_unbind_tcf,
484         .graft          = drr_graft_class,
485         .leaf           = drr_class_leaf,
486         .qlen_notify    = drr_qlen_notify,
487         .dump           = drr_dump_class,
488         .dump_stats     = drr_dump_class_stats,
489         .walk           = drr_walk,
490 };
491 
492 static struct Qdisc_ops drr_qdisc_ops __read_mostly = {
493         .cl_ops         = &drr_class_ops,
494         .id             = "drr",
495         .priv_size      = sizeof(struct drr_sched),
496         .enqueue        = drr_enqueue,
497         .dequeue        = drr_dequeue,
498         .peek           = qdisc_peek_dequeued,
499         .init           = drr_init_qdisc,
500         .reset          = drr_reset_qdisc,
501         .destroy        = drr_destroy_qdisc,
502         .owner          = THIS_MODULE,
503 };
504 
505 static int __init drr_init(void)
506 {
507         return register_qdisc(&drr_qdisc_ops);
508 }
509 
510 static void __exit drr_exit(void)
511 {
512         unregister_qdisc(&drr_qdisc_ops);
513 }
514 
515 module_init(drr_init);
516 module_exit(drr_exit);
517 MODULE_LICENSE("GPL");
518 

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