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 struct drr_class *drr_find_class(struct Qdisc *sch, u32 classid)
  39 {
  40         struct drr_sched *q = qdisc_priv(sch);
  41         struct Qdisc_class_common *clc;
  42
  43         clc = qdisc_class_find(&q->clhash, classid);
  44         if (clc == NULL)
  45                 return NULL;
  46         return container_of(clc, struct drr_class, common);
  47 }
  48
  49 static const struct nla_policy drr_policy[TCA_DRR_MAX + 1] = {
  50         [TCA_DRR_QUANTUM]       = { .type = NLA_U32 },
  51 };
  52
  53 static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
  54                             struct nlattr **tca, unsigned long *arg,
  55                             struct netlink_ext_ack *extack)
  56 {
  57         struct drr_sched *q = qdisc_priv(sch);
  58         struct drr_class *cl = (struct drr_class *)*arg;
  59         struct nlattr *opt = tca[TCA_OPTIONS];
  60         struct nlattr *tb[TCA_DRR_MAX + 1];
  61         u32 quantum;
  62         int err;
  63
  64         if (!opt) {
  65                 NL_SET_ERR_MSG(extack, "DRR options are required for this operation");
  66                 return -EINVAL;
  67         }
  68
  69         err = nla_parse_nested_deprecated(tb, TCA_DRR_MAX, opt, drr_policy,
  70                                           extack);
  71         if (err < 0)
  72                 return err;
  73
  74         if (tb[TCA_DRR_QUANTUM]) {
  75                 quantum = nla_get_u32(tb[TCA_DRR_QUANTUM]);
  76                 if (quantum == 0) {
  77                         NL_SET_ERR_MSG(extack, "Specified DRR quantum cannot be zero");
  78                         return -EINVAL;
  79                 }
  80         } else
  81                 quantum = psched_mtu(qdisc_dev(sch));
  82
  83         if (cl != NULL) {
  84                 if (tca[TCA_RATE]) {
  85                         err = gen_replace_estimator(&cl->bstats, NULL,
  86                                                     &cl->rate_est,
  87                                                     NULL, true,
  88                                                     tca[TCA_RATE]);
  89                         if (err) {
  90                                 NL_SET_ERR_MSG(extack, "Failed to replace estimator");
  91                                 return err;
  92                         }
  93                 }
  94
  95                 sch_tree_lock(sch);
  96                 if (tb[TCA_DRR_QUANTUM])
  97                         cl->quantum = quantum;
  98                 sch_tree_unlock(sch);
  99
 100                 return 0;
 101         }
 102
 103         cl = kzalloc(sizeof(struct drr_class), GFP_KERNEL);
 104         if (cl == NULL)
 105                 return -ENOBUFS;
 106
 107         gnet_stats_basic_sync_init(&cl->bstats);
 108         cl->common.classid = classid;
 109         cl->quantum        = quantum;
 110         cl->qdisc          = qdisc_create_dflt(sch->dev_queue,
 111                                                &pfifo_qdisc_ops, classid,
 112                                                NULL);
 113         if (cl->qdisc == NULL)
 114                 cl->qdisc = &noop_qdisc;
 115         else
 116                 qdisc_hash_add(cl->qdisc, true);
 117
 118         if (tca[TCA_RATE]) {
 119                 err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est,
 120                                             NULL, true, tca[TCA_RATE]);
 121                 if (err) {
 122                         NL_SET_ERR_MSG(extack, "Failed to replace estimator");
 123                         qdisc_put(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->rate_est);
 142         qdisc_put(cl->qdisc);
 143         kfree(cl);
 144 }
 145
 146 static int drr_delete_class(struct Qdisc *sch, unsigned long arg,
 147                             struct netlink_ext_ack *extack)
 148 {
 149         struct drr_sched *q = qdisc_priv(sch);
 150         struct drr_class *cl = (struct drr_class *)arg;
 151
 152         if (qdisc_class_in_use(&cl->common)) {
 153                 NL_SET_ERR_MSG(extack, "DRR class is in use");
 154                 return -EBUSY;
 155         }
 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)
 192                 qdisc_class_get(&cl->common);
 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         qdisc_class_put(&cl->common);
 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(d, NULL, &cl->bstats, true) < 0 ||
 270             gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
 271             gnet_stats_copy_queue(d, cl_q->cpu_qstats, &cl_q->qstats, qlen) < 0)
 272                 return -1;
 273
 274         return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
 275 }
 276
 277 static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 278 {
 279         struct drr_sched *q = qdisc_priv(sch);
 280         struct drr_class *cl;
 281         unsigned int i;
 282
 283         if (arg->stop)
 284                 return;
 285
 286         for (i = 0; i < q->clhash.hashsize; i++) {
 287                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
 288                         if (!tc_qdisc_stats_dump(sch, (unsigned long)cl, arg))
 289                                 return;
 290                 }
 291         }
 292 }
 293
 294 static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch,
 295                                       int *qerr)
 296 {
 297         struct drr_sched *q = qdisc_priv(sch);
 298         struct drr_class *cl;
 299         struct tcf_result res;
 300         struct tcf_proto *fl;
 301         int result;
 302
 303         if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
 304                 cl = drr_find_class(sch, skb->priority);
 305                 if (cl != NULL)
 306                         return cl;
 307         }
 308
 309         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 310         fl = rcu_dereference_bh(q->filter_list);
 311         result = tcf_classify(skb, NULL, fl, &res, false);
 312         if (result >= 0) {
 313 #ifdef CONFIG_NET_CLS_ACT
 314                 switch (result) {
 315                 case TC_ACT_QUEUED:
 316                 case TC_ACT_STOLEN:
 317                 case TC_ACT_TRAP:
 318                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
 319                         fallthrough;
 320                 case TC_ACT_SHOT:
 321                         return NULL;
 322                 }
 323 #endif
 324                 cl = (struct drr_class *)res.class;
 325                 if (cl == NULL)
 326                         cl = drr_find_class(sch, res.classid);
 327                 return cl;
 328         }
 329         return NULL;
 330 }
 331
 332 static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 333                        struct sk_buff **to_free)
 334 {
 335         unsigned int len = qdisc_pkt_len(skb);
 336         struct drr_sched *q = qdisc_priv(sch);
 337         struct drr_class *cl;
 338         int err = 0;
 339         bool first;
 340
 341         cl = drr_classify(skb, sch, &err);
 342         if (cl == NULL) {
 343                 if (err & __NET_XMIT_BYPASS)
 344                         qdisc_qstats_drop(sch);
 345                 __qdisc_drop(skb, to_free);
 346                 return err;
 347         }
 348
 349         first = !cl->qdisc->q.qlen;
 350         err = qdisc_enqueue(skb, cl->qdisc, to_free);
 351         if (unlikely(err != NET_XMIT_SUCCESS)) {
 352                 if (net_xmit_drop_count(err)) {
 353                         cl->qstats.drops++;
 354                         qdisc_qstats_drop(sch);
 355                 }
 356                 return err;
 357         }
 358
 359         if (first) {
 360                 list_add_tail(&cl->alist, &q->active);
 361                 cl->deficit = cl->quantum;
 362         }
 363
 364         sch->qstats.backlog += len;
 365         sch->q.qlen++;
 366         return err;
 367 }
 368
 369 static struct sk_buff *drr_dequeue(struct Qdisc *sch)
 370 {
 371         struct drr_sched *q = qdisc_priv(sch);
 372         struct drr_class *cl;
 373         struct sk_buff *skb;
 374         unsigned int len;
 375
 376         if (list_empty(&q->active))
 377                 goto out;
 378         while (1) {
 379                 cl = list_first_entry(&q->active, struct drr_class, alist);
 380                 skb = cl->qdisc->ops->peek(cl->qdisc);
 381                 if (skb == NULL) {
 382                         qdisc_warn_nonwc(__func__, cl->qdisc);
 383                         goto out;
 384                 }
 385
 386                 len = qdisc_pkt_len(skb);
 387                 if (len <= cl->deficit) {
 388                         cl->deficit -= len;
 389                         skb = qdisc_dequeue_peeked(cl->qdisc);
 390                         if (unlikely(skb == NULL))
 391                                 goto out;
 392                         if (cl->qdisc->q.qlen == 0)
 393                                 list_del(&cl->alist);
 394
 395                         bstats_update(&cl->bstats, skb);
 396                         qdisc_bstats_update(sch, skb);
 397                         qdisc_qstats_backlog_dec(sch, skb);
 398                         sch->q.qlen--;
 399                         return skb;
 400                 }
 401
 402                 cl->deficit += cl->quantum;
 403                 list_move_tail(&cl->alist, &q->active);
 404         }
 405 out:
 406         return NULL;
 407 }
 408
 409 static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt,
 410                           struct netlink_ext_ack *extack)
 411 {
 412         struct drr_sched *q = qdisc_priv(sch);
 413         int err;
 414
 415         err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
 416         if (err)
 417                 return err;
 418         err = qdisc_class_hash_init(&q->clhash);
 419         if (err < 0)
 420                 return err;
 421         INIT_LIST_HEAD(&q->active);
 422         return 0;
 423 }
 424
 425 static void drr_reset_qdisc(struct Qdisc *sch)
 426 {
 427         struct drr_sched *q = qdisc_priv(sch);
 428         struct drr_class *cl;
 429         unsigned int i;
 430
 431         for (i = 0; i < q->clhash.hashsize; i++) {
 432                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
 433                         if (cl->qdisc->q.qlen)
 434                                 list_del(&cl->alist);
 435                         qdisc_reset(cl->qdisc);
 436                 }
 437         }
 438 }
 439
 440 static void drr_destroy_qdisc(struct Qdisc *sch)
 441 {
 442         struct drr_sched *q = qdisc_priv(sch);
 443         struct drr_class *cl;
 444         struct hlist_node *next;
 445         unsigned int i;
 446
 447         tcf_block_put(q->block);
 448
 449         for (i = 0; i < q->clhash.hashsize; i++) {
 450                 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],
 451                                           common.hnode)
 452                         drr_destroy_class(sch, cl);
 453         }
 454         qdisc_class_hash_destroy(&q->clhash);
 455 }
 456
 457 static const struct Qdisc_class_ops drr_class_ops = {
 458         .change         = drr_change_class,
 459         .delete         = drr_delete_class,
 460         .find           = drr_search_class,
 461         .tcf_block      = drr_tcf_block,
 462         .bind_tcf       = drr_bind_tcf,
 463         .unbind_tcf     = drr_unbind_tcf,
 464         .graft          = drr_graft_class,
 465         .leaf           = drr_class_leaf,
 466         .qlen_notify    = drr_qlen_notify,
 467         .dump           = drr_dump_class,
 468         .dump_stats     = drr_dump_class_stats,
 469         .walk           = drr_walk,
 470 };
 471
 472 static struct Qdisc_ops drr_qdisc_ops __read_mostly = {
 473         .cl_ops         = &drr_class_ops,
 474         .id             = "drr",
 475         .priv_size      = sizeof(struct drr_sched),
 476         .enqueue        = drr_enqueue,
 477         .dequeue        = drr_dequeue,
 478         .peek           = qdisc_peek_dequeued,
 479         .init           = drr_init_qdisc,
 480         .reset          = drr_reset_qdisc,
 481         .destroy        = drr_destroy_qdisc,
 482         .owner          = THIS_MODULE,
 483 };
 484 MODULE_ALIAS_NET_SCH("drr");
 485
 486 static int __init drr_init(void)
 487 {
 488         return register_qdisc(&drr_qdisc_ops);
 489 }
 490
 491 static void __exit drr_exit(void)
 492 {
 493         unregister_qdisc(&drr_qdisc_ops);
 494 }
 495
 496 module_init(drr_init);
 497 module_exit(drr_exit);
 498 MODULE_LICENSE("GPL");
 499 MODULE_DESCRIPTION("Deficit Round Robin scheduler");