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Linux/net/sched/sch_drr.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * net/sched/sch_drr.c         Deficit Round Robin scheduler
  4  *
  5  * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
  6  */
  7 
  8 #include <linux/module.h>
  9 #include <linux/slab.h>
 10 #include <linux/init.h>
 11 #include <linux/errno.h>
 12 #include <linux/netdevice.h>
 13 #include <linux/pkt_sched.h>
 14 #include <net/sch_generic.h>
 15 #include <net/pkt_sched.h>
 16 #include <net/pkt_cls.h>
 17 
 18 struct drr_class {
 19         struct Qdisc_class_common       common;
 20         unsigned int                    filter_cnt;
 21 
 22         struct gnet_stats_basic_packed          bstats;
 23         struct gnet_stats_queue         qstats;
 24         struct net_rate_estimator __rcu *rate_est;
 25         struct list_head                alist;
 26         struct Qdisc                    *qdisc;
 27 
 28         u32                             quantum;
 29         u32                             deficit;
 30 };
 31 
 32 struct drr_sched {
 33         struct list_head                active;
 34         struct tcf_proto __rcu          *filter_list;
 35         struct tcf_block                *block;
 36         struct Qdisc_class_hash         clhash;
 37 };
 38 
 39 static struct drr_class *drr_find_class(struct Qdisc *sch, u32 classid)
 40 {
 41         struct drr_sched *q = qdisc_priv(sch);
 42         struct Qdisc_class_common *clc;
 43 
 44         clc = qdisc_class_find(&q->clhash, classid);
 45         if (clc == NULL)
 46                 return NULL;
 47         return container_of(clc, struct drr_class, common);
 48 }
 49 
 50 static const struct nla_policy drr_policy[TCA_DRR_MAX + 1] = {
 51         [TCA_DRR_QUANTUM]       = { .type = NLA_U32 },
 52 };
 53 
 54 static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 55                             struct nlattr **tca, unsigned long *arg,
 56                             struct netlink_ext_ack *extack)
 57 {
 58         struct drr_sched *q = qdisc_priv(sch);
 59         struct drr_class *cl = (struct drr_class *)*arg;
 60         struct nlattr *opt = tca[TCA_OPTIONS];
 61         struct nlattr *tb[TCA_DRR_MAX + 1];
 62         u32 quantum;
 63         int err;
 64 
 65         if (!opt) {
 66                 NL_SET_ERR_MSG(extack, "DRR options are required for this operation");
 67                 return -EINVAL;
 68         }
 69 
 70         err = nla_parse_nested_deprecated(tb, TCA_DRR_MAX, opt, drr_policy,
 71                                           extack);
 72         if (err < 0)
 73                 return err;
 74 
 75         if (tb[TCA_DRR_QUANTUM]) {
 76                 quantum = nla_get_u32(tb[TCA_DRR_QUANTUM]);
 77                 if (quantum == 0) {
 78                         NL_SET_ERR_MSG(extack, "Specified DRR quantum cannot be zero");
 79                         return -EINVAL;
 80                 }
 81         } else
 82                 quantum = psched_mtu(qdisc_dev(sch));
 83 
 84         if (cl != NULL) {
 85                 if (tca[TCA_RATE]) {
 86                         err = gen_replace_estimator(&cl->bstats, NULL,
 87                                                     &cl->rate_est,
 88                                                     NULL,
 89                                                     qdisc_root_sleeping_running(sch),
 90                                                     tca[TCA_RATE]);
 91                         if (err) {
 92                                 NL_SET_ERR_MSG(extack, "Failed to replace estimator");
 93                                 return err;
 94                         }
 95                 }
 96 
 97                 sch_tree_lock(sch);
 98                 if (tb[TCA_DRR_QUANTUM])
 99                         cl->quantum = quantum;
100                 sch_tree_unlock(sch);
101 
102                 return 0;
103         }
104 
105         cl = kzalloc(sizeof(struct drr_class), GFP_KERNEL);
106         if (cl == NULL)
107                 return -ENOBUFS;
108 
109         cl->common.classid = classid;
110         cl->quantum        = quantum;
111         cl->qdisc          = qdisc_create_dflt(sch->dev_queue,
112                                                &pfifo_qdisc_ops, classid,
113                                                NULL);
114         if (cl->qdisc == NULL)
115                 cl->qdisc = &noop_qdisc;
116         else
117                 qdisc_hash_add(cl->qdisc, true);
118 
119         if (tca[TCA_RATE]) {
120                 err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est,
121                                             NULL,
122                                             qdisc_root_sleeping_running(sch),
123                                             tca[TCA_RATE]);
124                 if (err) {
125                         NL_SET_ERR_MSG(extack, "Failed to replace estimator");
126                         qdisc_put(cl->qdisc);
127                         kfree(cl);
128                         return err;
129                 }
130         }
131 
132         sch_tree_lock(sch);
133         qdisc_class_hash_insert(&q->clhash, &cl->common);
134         sch_tree_unlock(sch);
135 
136         qdisc_class_hash_grow(sch, &q->clhash);
137 
138         *arg = (unsigned long)cl;
139         return 0;
140 }
141 
142 static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl)
143 {
144         gen_kill_estimator(&cl->rate_est);
145         qdisc_put(cl->qdisc);
146         kfree(cl);
147 }
148 
149 static int drr_delete_class(struct Qdisc *sch, unsigned long arg)
150 {
151         struct drr_sched *q = qdisc_priv(sch);
152         struct drr_class *cl = (struct drr_class *)arg;
153 
154         if (cl->filter_cnt > 0)
155                 return -EBUSY;
156 
157         sch_tree_lock(sch);
158 
159         qdisc_purge_queue(cl->qdisc);
160         qdisc_class_hash_remove(&q->clhash, &cl->common);
161 
162         sch_tree_unlock(sch);
163 
164         drr_destroy_class(sch, cl);
165         return 0;
166 }
167 
168 static unsigned long drr_search_class(struct Qdisc *sch, u32 classid)
169 {
170         return (unsigned long)drr_find_class(sch, classid);
171 }
172 
173 static struct tcf_block *drr_tcf_block(struct Qdisc *sch, unsigned long cl,
174                                        struct netlink_ext_ack *extack)
175 {
176         struct drr_sched *q = qdisc_priv(sch);
177 
178         if (cl) {
179                 NL_SET_ERR_MSG(extack, "DRR classid must be zero");
180                 return NULL;
181         }
182 
183         return q->block;
184 }
185 
186 static unsigned long drr_bind_tcf(struct Qdisc *sch, unsigned long parent,
187                                   u32 classid)
188 {
189         struct drr_class *cl = drr_find_class(sch, classid);
190 
191         if (cl != NULL)
192                 cl->filter_cnt++;
193 
194         return (unsigned long)cl;
195 }
196 
197 static void drr_unbind_tcf(struct Qdisc *sch, unsigned long arg)
198 {
199         struct drr_class *cl = (struct drr_class *)arg;
200 
201         cl->filter_cnt--;
202 }
203 
204 static int drr_graft_class(struct Qdisc *sch, unsigned long arg,
205                            struct Qdisc *new, struct Qdisc **old,
206                            struct netlink_ext_ack *extack)
207 {
208         struct drr_class *cl = (struct drr_class *)arg;
209 
210         if (new == NULL) {
211                 new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
212                                         cl->common.classid, NULL);
213                 if (new == NULL)
214                         new = &noop_qdisc;
215         }
216 
217         *old = qdisc_replace(sch, new, &cl->qdisc);
218         return 0;
219 }
220 
221 static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg)
222 {
223         struct drr_class *cl = (struct drr_class *)arg;
224 
225         return cl->qdisc;
226 }
227 
228 static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg)
229 {
230         struct drr_class *cl = (struct drr_class *)arg;
231 
232         list_del(&cl->alist);
233 }
234 
235 static int drr_dump_class(struct Qdisc *sch, unsigned long arg,
236                           struct sk_buff *skb, struct tcmsg *tcm)
237 {
238         struct drr_class *cl = (struct drr_class *)arg;
239         struct nlattr *nest;
240 
241         tcm->tcm_parent = TC_H_ROOT;
242         tcm->tcm_handle = cl->common.classid;
243         tcm->tcm_info   = cl->qdisc->handle;
244 
245         nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
246         if (nest == NULL)
247                 goto nla_put_failure;
248         if (nla_put_u32(skb, TCA_DRR_QUANTUM, cl->quantum))
249                 goto nla_put_failure;
250         return nla_nest_end(skb, nest);
251 
252 nla_put_failure:
253         nla_nest_cancel(skb, nest);
254         return -EMSGSIZE;
255 }
256 
257 static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg,
258                                 struct gnet_dump *d)
259 {
260         struct drr_class *cl = (struct drr_class *)arg;
261         __u32 qlen = qdisc_qlen_sum(cl->qdisc);
262         struct Qdisc *cl_q = cl->qdisc;
263         struct tc_drr_stats xstats;
264 
265         memset(&xstats, 0, sizeof(xstats));
266         if (qlen)
267                 xstats.deficit = cl->deficit;
268 
269         if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
270                                   d, NULL, &cl->bstats) < 0 ||
271             gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
272             gnet_stats_copy_queue(d, cl_q->cpu_qstats, &cl_q->qstats, qlen) < 0)
273                 return -1;
274 
275         return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
276 }
277 
278 static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg)
279 {
280         struct drr_sched *q = qdisc_priv(sch);
281         struct drr_class *cl;
282         unsigned int i;
283 
284         if (arg->stop)
285                 return;
286 
287         for (i = 0; i < q->clhash.hashsize; i++) {
288                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
289                         if (arg->count < arg->skip) {
290                                 arg->count++;
291                                 continue;
292                         }
293                         if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
294                                 arg->stop = 1;
295                                 return;
296                         }
297                         arg->count++;
298                 }
299         }
300 }
301 
302 static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch,
303                                       int *qerr)
304 {
305         struct drr_sched *q = qdisc_priv(sch);
306         struct drr_class *cl;
307         struct tcf_result res;
308         struct tcf_proto *fl;
309         int result;
310 
311         if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
312                 cl = drr_find_class(sch, skb->priority);
313                 if (cl != NULL)
314                         return cl;
315         }
316 
317         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
318         fl = rcu_dereference_bh(q->filter_list);
319         result = tcf_classify(skb, fl, &res, false);
320         if (result >= 0) {
321 #ifdef CONFIG_NET_CLS_ACT
322                 switch (result) {
323                 case TC_ACT_QUEUED:
324                 case TC_ACT_STOLEN:
325                 case TC_ACT_TRAP:
326                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
327                         fallthrough;
328                 case TC_ACT_SHOT:
329                         return NULL;
330                 }
331 #endif
332                 cl = (struct drr_class *)res.class;
333                 if (cl == NULL)
334                         cl = drr_find_class(sch, res.classid);
335                 return cl;
336         }
337         return NULL;
338 }
339 
340 static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch,
341                        struct sk_buff **to_free)
342 {
343         unsigned int len = qdisc_pkt_len(skb);
344         struct drr_sched *q = qdisc_priv(sch);
345         struct drr_class *cl;
346         int err = 0;
347         bool first;
348 
349         cl = drr_classify(skb, sch, &err);
350         if (cl == NULL) {
351                 if (err & __NET_XMIT_BYPASS)
352                         qdisc_qstats_drop(sch);
353                 __qdisc_drop(skb, to_free);
354                 return err;
355         }
356 
357         first = !cl->qdisc->q.qlen;
358         err = qdisc_enqueue(skb, cl->qdisc, to_free);
359         if (unlikely(err != NET_XMIT_SUCCESS)) {
360                 if (net_xmit_drop_count(err)) {
361                         cl->qstats.drops++;
362                         qdisc_qstats_drop(sch);
363                 }
364                 return err;
365         }
366 
367         if (first) {
368                 list_add_tail(&cl->alist, &q->active);
369                 cl->deficit = cl->quantum;
370         }
371 
372         sch->qstats.backlog += len;
373         sch->q.qlen++;
374         return err;
375 }
376 
377 static struct sk_buff *drr_dequeue(struct Qdisc *sch)
378 {
379         struct drr_sched *q = qdisc_priv(sch);
380         struct drr_class *cl;
381         struct sk_buff *skb;
382         unsigned int len;
383 
384         if (list_empty(&q->active))
385                 goto out;
386         while (1) {
387                 cl = list_first_entry(&q->active, struct drr_class, alist);
388                 skb = cl->qdisc->ops->peek(cl->qdisc);
389                 if (skb == NULL) {
390                         qdisc_warn_nonwc(__func__, cl->qdisc);
391                         goto out;
392                 }
393 
394                 len = qdisc_pkt_len(skb);
395                 if (len <= cl->deficit) {
396                         cl->deficit -= len;
397                         skb = qdisc_dequeue_peeked(cl->qdisc);
398                         if (unlikely(skb == NULL))
399                                 goto out;
400                         if (cl->qdisc->q.qlen == 0)
401                                 list_del(&cl->alist);
402 
403                         bstats_update(&cl->bstats, skb);
404                         qdisc_bstats_update(sch, skb);
405                         qdisc_qstats_backlog_dec(sch, skb);
406                         sch->q.qlen--;
407                         return skb;
408                 }
409 
410                 cl->deficit += cl->quantum;
411                 list_move_tail(&cl->alist, &q->active);
412         }
413 out:
414         return NULL;
415 }
416 
417 static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt,
418                           struct netlink_ext_ack *extack)
419 {
420         struct drr_sched *q = qdisc_priv(sch);
421         int err;
422 
423         err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
424         if (err)
425                 return err;
426         err = qdisc_class_hash_init(&q->clhash);
427         if (err < 0)
428                 return err;
429         INIT_LIST_HEAD(&q->active);
430         return 0;
431 }
432 
433 static void drr_reset_qdisc(struct Qdisc *sch)
434 {
435         struct drr_sched *q = qdisc_priv(sch);
436         struct drr_class *cl;
437         unsigned int i;
438 
439         for (i = 0; i < q->clhash.hashsize; i++) {
440                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
441                         if (cl->qdisc->q.qlen)
442                                 list_del(&cl->alist);
443                         qdisc_reset(cl->qdisc);
444                 }
445         }
446         sch->qstats.backlog = 0;
447         sch->q.qlen = 0;
448 }
449 
450 static void drr_destroy_qdisc(struct Qdisc *sch)
451 {
452         struct drr_sched *q = qdisc_priv(sch);
453         struct drr_class *cl;
454         struct hlist_node *next;
455         unsigned int i;
456 
457         tcf_block_put(q->block);
458 
459         for (i = 0; i < q->clhash.hashsize; i++) {
460                 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],
461                                           common.hnode)
462                         drr_destroy_class(sch, cl);
463         }
464         qdisc_class_hash_destroy(&q->clhash);
465 }
466 
467 static const struct Qdisc_class_ops drr_class_ops = {
468         .change         = drr_change_class,
469         .delete         = drr_delete_class,
470         .find           = drr_search_class,
471         .tcf_block      = drr_tcf_block,
472         .bind_tcf       = drr_bind_tcf,
473         .unbind_tcf     = drr_unbind_tcf,
474         .graft          = drr_graft_class,
475         .leaf           = drr_class_leaf,
476         .qlen_notify    = drr_qlen_notify,
477         .dump           = drr_dump_class,
478         .dump_stats     = drr_dump_class_stats,
479         .walk           = drr_walk,
480 };
481 
482 static struct Qdisc_ops drr_qdisc_ops __read_mostly = {
483         .cl_ops         = &drr_class_ops,
484         .id             = "drr",
485         .priv_size      = sizeof(struct drr_sched),
486         .enqueue        = drr_enqueue,
487         .dequeue        = drr_dequeue,
488         .peek           = qdisc_peek_dequeued,
489         .init           = drr_init_qdisc,
490         .reset          = drr_reset_qdisc,
491         .destroy        = drr_destroy_qdisc,
492         .owner          = THIS_MODULE,
493 };
494 
495 static int __init drr_init(void)
496 {
497         return register_qdisc(&drr_qdisc_ops);
498 }
499 
500 static void __exit drr_exit(void)
501 {
502         unregister_qdisc(&drr_qdisc_ops);
503 }
504 
505 module_init(drr_init);
506 module_exit(drr_exit);
507 MODULE_LICENSE("GPL");
508 

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