net/sched/sch_drr.c

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