linux/net/sched/sch_drr.c
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   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/init.h>
  13#include <linux/errno.h>
  14#include <linux/netdevice.h>
  15#include <linux/pkt_sched.h>
  16#include <net/sch_generic.h>
  17#include <net/pkt_sched.h>
  18#include <net/pkt_cls.h>
  19
  20struct drr_class {
  21        struct Qdisc_class_common       common;
  22        unsigned int                    refcnt;
  23        unsigned int                    filter_cnt;
  24
  25        struct gnet_stats_basic         bstats;
  26        struct gnet_stats_queue         qstats;
  27        struct gnet_stats_rate_est      rate_est;
  28        struct list_head                alist;
  29        struct Qdisc                    *qdisc;
  30
  31        u32                             quantum;
  32        u32                             deficit;
  33};
  34
  35struct drr_sched {
  36        struct list_head                active;
  37        struct tcf_proto                *filter_list;
  38        struct Qdisc_class_hash         clhash;
  39};
  40
  41static struct drr_class *drr_find_class(struct Qdisc *sch, u32 classid)
  42{
  43        struct drr_sched *q = qdisc_priv(sch);
  44        struct Qdisc_class_common *clc;
  45
  46        clc = qdisc_class_find(&q->clhash, classid);
  47        if (clc == NULL)
  48                return NULL;
  49        return container_of(clc, struct drr_class, common);
  50}
  51
  52static void drr_purge_queue(struct drr_class *cl)
  53{
  54        unsigned int len = cl->qdisc->q.qlen;
  55
  56        qdisc_reset(cl->qdisc);
  57        qdisc_tree_decrease_qlen(cl->qdisc, len);
  58}
  59
  60static const struct nla_policy drr_policy[TCA_DRR_MAX + 1] = {
  61        [TCA_DRR_QUANTUM]       = { .type = NLA_U32 },
  62};
  63
  64static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
  65                            struct nlattr **tca, unsigned long *arg)
  66{
  67        struct drr_sched *q = qdisc_priv(sch);
  68        struct drr_class *cl = (struct drr_class *)*arg;
  69        struct nlattr *opt = tca[TCA_OPTIONS];
  70        struct nlattr *tb[TCA_DRR_MAX + 1];
  71        u32 quantum;
  72        int err;
  73
  74        if (!opt)
  75                return -EINVAL;
  76
  77        err = nla_parse_nested(tb, TCA_DRR_MAX, opt, drr_policy);
  78        if (err < 0)
  79                return err;
  80
  81        if (tb[TCA_DRR_QUANTUM]) {
  82                quantum = nla_get_u32(tb[TCA_DRR_QUANTUM]);
  83                if (quantum == 0)
  84                        return -EINVAL;
  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, &cl->rate_est,
  91                                                    qdisc_root_sleeping_lock(sch),
  92                                                    tca[TCA_RATE]);
  93                        if (err)
  94                                return err;
  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->refcnt         = 1;
 110        cl->common.classid = classid;
 111        cl->quantum        = quantum;
 112        cl->qdisc          = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue,
 113                                               &pfifo_qdisc_ops, classid);
 114        if (cl->qdisc == NULL)
 115                cl->qdisc = &noop_qdisc;
 116
 117        if (tca[TCA_RATE]) {
 118                err = gen_replace_estimator(&cl->bstats, &cl->rate_est,
 119                                            qdisc_root_sleeping_lock(sch),
 120                                            tca[TCA_RATE]);
 121                if (err) {
 122                        qdisc_destroy(cl->qdisc);
 123                        kfree(cl);
 124                        return err;
 125                }
 126        }
 127
 128        sch_tree_lock(sch);
 129        qdisc_class_hash_insert(&q->clhash, &cl->common);
 130        sch_tree_unlock(sch);
 131
 132        qdisc_class_hash_grow(sch, &q->clhash);
 133
 134        *arg = (unsigned long)cl;
 135        return 0;
 136}
 137
 138static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl)
 139{
 140        gen_kill_estimator(&cl->bstats, &cl->rate_est);
 141        qdisc_destroy(cl->qdisc);
 142        kfree(cl);
 143}
 144
 145static int drr_delete_class(struct Qdisc *sch, unsigned long arg)
 146{
 147        struct drr_sched *q = qdisc_priv(sch);
 148        struct drr_class *cl = (struct drr_class *)arg;
 149
 150        if (cl->filter_cnt > 0)
 151                return -EBUSY;
 152
 153        sch_tree_lock(sch);
 154
 155        drr_purge_queue(cl);
 156        qdisc_class_hash_remove(&q->clhash, &cl->common);
 157
 158        if (--cl->refcnt == 0)
 159                drr_destroy_class(sch, cl);
 160
 161        sch_tree_unlock(sch);
 162        return 0;
 163}
 164
 165static unsigned long drr_get_class(struct Qdisc *sch, u32 classid)
 166{
 167        struct drr_class *cl = drr_find_class(sch, classid);
 168
 169        if (cl != NULL)
 170                cl->refcnt++;
 171
 172        return (unsigned long)cl;
 173}
 174
 175static void drr_put_class(struct Qdisc *sch, unsigned long arg)
 176{
 177        struct drr_class *cl = (struct drr_class *)arg;
 178
 179        if (--cl->refcnt == 0)
 180                drr_destroy_class(sch, cl);
 181}
 182
 183static struct tcf_proto **drr_tcf_chain(struct Qdisc *sch, unsigned long cl)
 184{
 185        struct drr_sched *q = qdisc_priv(sch);
 186
 187        if (cl)
 188                return NULL;
 189
 190        return &q->filter_list;
 191}
 192
 193static unsigned long drr_bind_tcf(struct Qdisc *sch, unsigned long parent,
 194                                  u32 classid)
 195{
 196        struct drr_class *cl = drr_find_class(sch, classid);
 197
 198        if (cl != NULL)
 199                cl->filter_cnt++;
 200
 201        return (unsigned long)cl;
 202}
 203
 204static void drr_unbind_tcf(struct Qdisc *sch, unsigned long arg)
 205{
 206        struct drr_class *cl = (struct drr_class *)arg;
 207
 208        cl->filter_cnt--;
 209}
 210
 211static int drr_graft_class(struct Qdisc *sch, unsigned long arg,
 212                           struct Qdisc *new, struct Qdisc **old)
 213{
 214        struct drr_class *cl = (struct drr_class *)arg;
 215
 216        if (new == NULL) {
 217                new = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue,
 218                                        &pfifo_qdisc_ops, cl->common.classid);
 219                if (new == NULL)
 220                        new = &noop_qdisc;
 221        }
 222
 223        sch_tree_lock(sch);
 224        drr_purge_queue(cl);
 225        *old = cl->qdisc;
 226        cl->qdisc = new;
 227        sch_tree_unlock(sch);
 228        return 0;
 229}
 230
 231static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg)
 232{
 233        struct drr_class *cl = (struct drr_class *)arg;
 234
 235        return cl->qdisc;
 236}
 237
 238static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg)
 239{
 240        struct drr_class *cl = (struct drr_class *)arg;
 241
 242        if (cl->qdisc->q.qlen == 0)
 243                list_del(&cl->alist);
 244}
 245
 246static int drr_dump_class(struct Qdisc *sch, unsigned long arg,
 247                          struct sk_buff *skb, struct tcmsg *tcm)
 248{
 249        struct drr_class *cl = (struct drr_class *)arg;
 250        struct nlattr *nest;
 251
 252        tcm->tcm_parent = TC_H_ROOT;
 253        tcm->tcm_handle = cl->common.classid;
 254        tcm->tcm_info   = cl->qdisc->handle;
 255
 256        nest = nla_nest_start(skb, TCA_OPTIONS);
 257        if (nest == NULL)
 258                goto nla_put_failure;
 259        NLA_PUT_U32(skb, TCA_DRR_QUANTUM, cl->quantum);
 260        return nla_nest_end(skb, nest);
 261
 262nla_put_failure:
 263        nla_nest_cancel(skb, nest);
 264        return -EMSGSIZE;
 265}
 266
 267static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg,
 268                                struct gnet_dump *d)
 269{
 270        struct drr_class *cl = (struct drr_class *)arg;
 271        struct tc_drr_stats xstats;
 272
 273        memset(&xstats, 0, sizeof(xstats));
 274        if (cl->qdisc->q.qlen)
 275                xstats.deficit = cl->deficit;
 276
 277        if (gnet_stats_copy_basic(d, &cl->bstats) < 0 ||
 278            gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
 279            gnet_stats_copy_queue(d, &cl->qdisc->qstats) < 0)
 280                return -1;
 281
 282        return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
 283}
 284
 285static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 286{
 287        struct drr_sched *q = qdisc_priv(sch);
 288        struct drr_class *cl;
 289        struct hlist_node *n;
 290        unsigned int i;
 291
 292        if (arg->stop)
 293                return;
 294
 295        for (i = 0; i < q->clhash.hashsize; i++) {
 296                hlist_for_each_entry(cl, n, &q->clhash.hash[i], common.hnode) {
 297                        if (arg->count < arg->skip) {
 298                                arg->count++;
 299                                continue;
 300                        }
 301                        if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
 302                                arg->stop = 1;
 303                                return;
 304                        }
 305                        arg->count++;
 306                }
 307        }
 308}
 309
 310static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch,
 311                                      int *qerr)
 312{
 313        struct drr_sched *q = qdisc_priv(sch);
 314        struct drr_class *cl;
 315        struct tcf_result res;
 316        int result;
 317
 318        if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
 319                cl = drr_find_class(sch, skb->priority);
 320                if (cl != NULL)
 321                        return cl;
 322        }
 323
 324        *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 325        result = tc_classify(skb, q->filter_list, &res);
 326        if (result >= 0) {
 327#ifdef CONFIG_NET_CLS_ACT
 328                switch (result) {
 329                case TC_ACT_QUEUED:
 330                case TC_ACT_STOLEN:
 331                        *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
 332                case TC_ACT_SHOT:
 333                        return NULL;
 334                }
 335#endif
 336                cl = (struct drr_class *)res.class;
 337                if (cl == NULL)
 338                        cl = drr_find_class(sch, res.classid);
 339                return cl;
 340        }
 341        return NULL;
 342}
 343
 344static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 345{
 346        struct drr_sched *q = qdisc_priv(sch);
 347        struct drr_class *cl;
 348        unsigned int len;
 349        int err;
 350
 351        cl = drr_classify(skb, sch, &err);
 352        if (cl == NULL) {
 353                if (err & __NET_XMIT_BYPASS)
 354                        sch->qstats.drops++;
 355                kfree_skb(skb);
 356                return err;
 357        }
 358
 359        len = qdisc_pkt_len(skb);
 360        err = qdisc_enqueue(skb, cl->qdisc);
 361        if (unlikely(err != NET_XMIT_SUCCESS)) {
 362                if (net_xmit_drop_count(err)) {
 363                        cl->qstats.drops++;
 364                        sch->qstats.drops++;
 365                }
 366                return err;
 367        }
 368
 369        if (cl->qdisc->q.qlen == 1) {
 370                list_add_tail(&cl->alist, &q->active);
 371                cl->deficit = cl->quantum;
 372        }
 373
 374        cl->bstats.packets++;
 375        cl->bstats.bytes += len;
 376        sch->bstats.packets++;
 377        sch->bstats.bytes += len;
 378
 379        sch->q.qlen++;
 380        return err;
 381}
 382
 383static struct sk_buff *drr_dequeue(struct Qdisc *sch)
 384{
 385        struct drr_sched *q = qdisc_priv(sch);
 386        struct drr_class *cl;
 387        struct sk_buff *skb;
 388        unsigned int len;
 389
 390        if (list_empty(&q->active))
 391                goto out;
 392        while (1) {
 393                cl = list_first_entry(&q->active, struct drr_class, alist);
 394                skb = cl->qdisc->ops->peek(cl->qdisc);
 395                if (skb == NULL)
 396                        goto out;
 397
 398                len = qdisc_pkt_len(skb);
 399                if (len <= cl->deficit) {
 400                        cl->deficit -= len;
 401                        skb = qdisc_dequeue_peeked(cl->qdisc);
 402                        if (cl->qdisc->q.qlen == 0)
 403                                list_del(&cl->alist);
 404                        sch->q.qlen--;
 405                        return skb;
 406                }
 407
 408                cl->deficit += cl->quantum;
 409                list_move_tail(&cl->alist, &q->active);
 410        }
 411out:
 412        return NULL;
 413}
 414
 415static unsigned int drr_drop(struct Qdisc *sch)
 416{
 417        struct drr_sched *q = qdisc_priv(sch);
 418        struct drr_class *cl;
 419        unsigned int len;
 420
 421        list_for_each_entry(cl, &q->active, alist) {
 422                if (cl->qdisc->ops->drop) {
 423                        len = cl->qdisc->ops->drop(cl->qdisc);
 424                        if (len > 0) {
 425                                sch->q.qlen--;
 426                                if (cl->qdisc->q.qlen == 0)
 427                                        list_del(&cl->alist);
 428                                return len;
 429                        }
 430                }
 431        }
 432        return 0;
 433}
 434
 435static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
 436{
 437        struct drr_sched *q = qdisc_priv(sch);
 438        int err;
 439
 440        err = qdisc_class_hash_init(&q->clhash);
 441        if (err < 0)
 442                return err;
 443        INIT_LIST_HEAD(&q->active);
 444        return 0;
 445}
 446
 447static void drr_reset_qdisc(struct Qdisc *sch)
 448{
 449        struct drr_sched *q = qdisc_priv(sch);
 450        struct drr_class *cl;
 451        struct hlist_node *n;
 452        unsigned int i;
 453
 454        for (i = 0; i < q->clhash.hashsize; i++) {
 455                hlist_for_each_entry(cl, n, &q->clhash.hash[i], common.hnode) {
 456                        if (cl->qdisc->q.qlen)
 457                                list_del(&cl->alist);
 458                        qdisc_reset(cl->qdisc);
 459                }
 460        }
 461        sch->q.qlen = 0;
 462}
 463
 464static void drr_destroy_qdisc(struct Qdisc *sch)
 465{
 466        struct drr_sched *q = qdisc_priv(sch);
 467        struct drr_class *cl;
 468        struct hlist_node *n, *next;
 469        unsigned int i;
 470
 471        tcf_destroy_chain(&q->filter_list);
 472
 473        for (i = 0; i < q->clhash.hashsize; i++) {
 474                hlist_for_each_entry_safe(cl, n, next, &q->clhash.hash[i],
 475                                          common.hnode)
 476                        drr_destroy_class(sch, cl);
 477        }
 478        qdisc_class_hash_destroy(&q->clhash);
 479}
 480
 481static const struct Qdisc_class_ops drr_class_ops = {
 482        .change         = drr_change_class,
 483        .delete         = drr_delete_class,
 484        .get            = drr_get_class,
 485        .put            = drr_put_class,
 486        .tcf_chain      = drr_tcf_chain,
 487        .bind_tcf       = drr_bind_tcf,
 488        .unbind_tcf     = drr_unbind_tcf,
 489        .graft          = drr_graft_class,
 490        .leaf           = drr_class_leaf,
 491        .qlen_notify    = drr_qlen_notify,
 492        .dump           = drr_dump_class,
 493        .dump_stats     = drr_dump_class_stats,
 494        .walk           = drr_walk,
 495};
 496
 497static struct Qdisc_ops drr_qdisc_ops __read_mostly = {
 498        .cl_ops         = &drr_class_ops,
 499        .id             = "drr",
 500        .priv_size      = sizeof(struct drr_sched),
 501        .enqueue        = drr_enqueue,
 502        .dequeue        = drr_dequeue,
 503        .peek           = qdisc_peek_dequeued,
 504        .drop           = drr_drop,
 505        .init           = drr_init_qdisc,
 506        .reset          = drr_reset_qdisc,
 507        .destroy        = drr_destroy_qdisc,
 508        .owner          = THIS_MODULE,
 509};
 510
 511static int __init drr_init(void)
 512{
 513        return register_qdisc(&drr_qdisc_ops);
 514}
 515
 516static void __exit drr_exit(void)
 517{
 518        unregister_qdisc(&drr_qdisc_ops);
 519}
 520
 521module_init(drr_init);
 522module_exit(drr_exit);
 523MODULE_LICENSE("GPL");
 524