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