net/sched/sch_drr.c

   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                         /* fall through */
 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");