net/sched/sch_red.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * net/sched/sch_red.c  Random Early Detection queue.
   4  *
   5  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
   6  *
   7  * Changes:
   8  * J Hadi Salim 980914: computation fixes
   9  * Alexey Makarenko <makar@phoenix.kharkov.ua> 990814: qave on idle link was calculated incorrectly.
  10  * J Hadi Salim 980816:  ECN support
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/types.h>
  15 #include <linux/kernel.h>
  16 #include <linux/skbuff.h>
  17 #include <net/pkt_sched.h>
  18 #include <net/pkt_cls.h>
  19 #include <net/inet_ecn.h>
  20 #include <net/red.h>
  21
  22
  23 /*      Parameters, settable by user:
  24         -----------------------------
  25
  26         limit           - bytes (must be > qth_max + burst)
  27
  28         Hard limit on queue length, should be chosen >qth_max
  29         to allow packet bursts. This parameter does not
  30         affect the algorithms behaviour and can be chosen
  31         arbitrarily high (well, less than ram size)
  32         Really, this limit will never be reached
  33         if RED works correctly.
  34  */
  35
  36 struct red_sched_data {
  37         u32                     limit;          /* HARD maximal queue length */
  38
  39         unsigned char           flags;
  40         /* Non-flags in tc_red_qopt.flags. */
  41         unsigned char           userbits;
  42
  43         struct timer_list       adapt_timer;
  44         struct Qdisc            *sch;
  45         struct red_parms        parms;
  46         struct red_vars         vars;
  47         struct red_stats        stats;
  48         struct Qdisc            *qdisc;
  49         struct tcf_qevent       qe_early_drop;
  50         struct tcf_qevent       qe_mark;
  51 };
  52
  53 #define TC_RED_SUPPORTED_FLAGS (TC_RED_HISTORIC_FLAGS | TC_RED_NODROP)
  54
  55 static inline int red_use_ecn(struct red_sched_data *q)
  56 {
  57         return q->flags & TC_RED_ECN;
  58 }
  59
  60 static inline int red_use_harddrop(struct red_sched_data *q)
  61 {
  62         return q->flags & TC_RED_HARDDROP;
  63 }
  64
  65 static int red_use_nodrop(struct red_sched_data *q)
  66 {
  67         return q->flags & TC_RED_NODROP;
  68 }
  69
  70 static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch,
  71                        struct sk_buff **to_free)
  72 {
  73         struct red_sched_data *q = qdisc_priv(sch);
  74         struct Qdisc *child = q->qdisc;
  75         int ret;
  76
  77         q->vars.qavg = red_calc_qavg(&q->parms,
  78                                      &q->vars,
  79                                      child->qstats.backlog);
  80
  81         if (red_is_idling(&q->vars))
  82                 red_end_of_idle_period(&q->vars);
  83
  84         switch (red_action(&q->parms, &q->vars, q->vars.qavg)) {
  85         case RED_DONT_MARK:
  86                 break;
  87
  88         case RED_PROB_MARK:
  89                 qdisc_qstats_overlimit(sch);
  90                 if (!red_use_ecn(q)) {
  91                         q->stats.prob_drop++;
  92                         goto congestion_drop;
  93                 }
  94
  95                 if (INET_ECN_set_ce(skb)) {
  96                         q->stats.prob_mark++;
  97                         skb = tcf_qevent_handle(&q->qe_mark, sch, skb, to_free, &ret);
  98                         if (!skb)
  99                                 return NET_XMIT_CN | ret;
 100                 } else if (!red_use_nodrop(q)) {
 101                         q->stats.prob_drop++;
 102                         goto congestion_drop;
 103                 }
 104
 105                 /* Non-ECT packet in ECN nodrop mode: queue it. */
 106                 break;
 107
 108         case RED_HARD_MARK:
 109                 qdisc_qstats_overlimit(sch);
 110                 if (red_use_harddrop(q) || !red_use_ecn(q)) {
 111                         q->stats.forced_drop++;
 112                         goto congestion_drop;
 113                 }
 114
 115                 if (INET_ECN_set_ce(skb)) {
 116                         q->stats.forced_mark++;
 117                         skb = tcf_qevent_handle(&q->qe_mark, sch, skb, to_free, &ret);
 118                         if (!skb)
 119                                 return NET_XMIT_CN | ret;
 120                 } else if (!red_use_nodrop(q)) {
 121                         q->stats.forced_drop++;
 122                         goto congestion_drop;
 123                 }
 124
 125                 /* Non-ECT packet in ECN nodrop mode: queue it. */
 126                 break;
 127         }
 128
 129         ret = qdisc_enqueue(skb, child, to_free);
 130         if (likely(ret == NET_XMIT_SUCCESS)) {
 131                 qdisc_qstats_backlog_inc(sch, skb);
 132                 sch->q.qlen++;
 133         } else if (net_xmit_drop_count(ret)) {
 134                 q->stats.pdrop++;
 135                 qdisc_qstats_drop(sch);
 136         }
 137         return ret;
 138
 139 congestion_drop:
 140         skb = tcf_qevent_handle(&q->qe_early_drop, sch, skb, to_free, &ret);
 141         if (!skb)
 142                 return NET_XMIT_CN | ret;
 143
 144         qdisc_drop(skb, sch, to_free);
 145         return NET_XMIT_CN;
 146 }
 147
 148 static struct sk_buff *red_dequeue(struct Qdisc *sch)
 149 {
 150         struct sk_buff *skb;
 151         struct red_sched_data *q = qdisc_priv(sch);
 152         struct Qdisc *child = q->qdisc;
 153
 154         skb = child->dequeue(child);
 155         if (skb) {
 156                 qdisc_bstats_update(sch, skb);
 157                 qdisc_qstats_backlog_dec(sch, skb);
 158                 sch->q.qlen--;
 159         } else {
 160                 if (!red_is_idling(&q->vars))
 161                         red_start_of_idle_period(&q->vars);
 162         }
 163         return skb;
 164 }
 165
 166 static struct sk_buff *red_peek(struct Qdisc *sch)
 167 {
 168         struct red_sched_data *q = qdisc_priv(sch);
 169         struct Qdisc *child = q->qdisc;
 170
 171         return child->ops->peek(child);
 172 }
 173
 174 static void red_reset(struct Qdisc *sch)
 175 {
 176         struct red_sched_data *q = qdisc_priv(sch);
 177
 178         qdisc_reset(q->qdisc);
 179         sch->qstats.backlog = 0;
 180         sch->q.qlen = 0;
 181         red_restart(&q->vars);
 182 }
 183
 184 static int red_offload(struct Qdisc *sch, bool enable)
 185 {
 186         struct red_sched_data *q = qdisc_priv(sch);
 187         struct net_device *dev = qdisc_dev(sch);
 188         struct tc_red_qopt_offload opt = {
 189                 .handle = sch->handle,
 190                 .parent = sch->parent,
 191         };
 192
 193         if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc)
 194                 return -EOPNOTSUPP;
 195
 196         if (enable) {
 197                 opt.command = TC_RED_REPLACE;
 198                 opt.set.min = q->parms.qth_min >> q->parms.Wlog;
 199                 opt.set.max = q->parms.qth_max >> q->parms.Wlog;
 200                 opt.set.probability = q->parms.max_P;
 201                 opt.set.limit = q->limit;
 202                 opt.set.is_ecn = red_use_ecn(q);
 203                 opt.set.is_harddrop = red_use_harddrop(q);
 204                 opt.set.is_nodrop = red_use_nodrop(q);
 205                 opt.set.qstats = &sch->qstats;
 206         } else {
 207                 opt.command = TC_RED_DESTROY;
 208         }
 209
 210         return dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED, &opt);
 211 }
 212
 213 static void red_destroy(struct Qdisc *sch)
 214 {
 215         struct red_sched_data *q = qdisc_priv(sch);
 216
 217         tcf_qevent_destroy(&q->qe_mark, sch);
 218         tcf_qevent_destroy(&q->qe_early_drop, sch);
 219         del_timer_sync(&q->adapt_timer);
 220         red_offload(sch, false);
 221         qdisc_put(q->qdisc);
 222 }
 223
 224 static const struct nla_policy red_policy[TCA_RED_MAX + 1] = {
 225         [TCA_RED_UNSPEC] = { .strict_start_type = TCA_RED_FLAGS },
 226         [TCA_RED_PARMS] = { .len = sizeof(struct tc_red_qopt) },
 227         [TCA_RED_STAB]  = { .len = RED_STAB_SIZE },
 228         [TCA_RED_MAX_P] = { .type = NLA_U32 },
 229         [TCA_RED_FLAGS] = NLA_POLICY_BITFIELD32(TC_RED_SUPPORTED_FLAGS),
 230         [TCA_RED_EARLY_DROP_BLOCK] = { .type = NLA_U32 },
 231         [TCA_RED_MARK_BLOCK] = { .type = NLA_U32 },
 232 };
 233
 234 static int __red_change(struct Qdisc *sch, struct nlattr **tb,
 235                         struct netlink_ext_ack *extack)
 236 {
 237         struct Qdisc *old_child = NULL, *child = NULL;
 238         struct red_sched_data *q = qdisc_priv(sch);
 239         struct nla_bitfield32 flags_bf;
 240         struct tc_red_qopt *ctl;
 241         unsigned char userbits;
 242         unsigned char flags;
 243         int err;
 244         u32 max_P;
 245
 246         if (tb[TCA_RED_PARMS] == NULL ||
 247             tb[TCA_RED_STAB] == NULL)
 248                 return -EINVAL;
 249
 250         max_P = tb[TCA_RED_MAX_P] ? nla_get_u32(tb[TCA_RED_MAX_P]) : 0;
 251
 252         ctl = nla_data(tb[TCA_RED_PARMS]);
 253         if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog))
 254                 return -EINVAL;
 255
 256         err = red_get_flags(ctl->flags, TC_RED_HISTORIC_FLAGS,
 257                             tb[TCA_RED_FLAGS], TC_RED_SUPPORTED_FLAGS,
 258                             &flags_bf, &userbits, extack);
 259         if (err)
 260                 return err;
 261
 262         if (ctl->limit > 0) {
 263                 child = fifo_create_dflt(sch, &bfifo_qdisc_ops, ctl->limit,
 264                                          extack);
 265                 if (IS_ERR(child))
 266                         return PTR_ERR(child);
 267
 268                 /* child is fifo, no need to check for noop_qdisc */
 269                 qdisc_hash_add(child, true);
 270         }
 271
 272         sch_tree_lock(sch);
 273
 274         flags = (q->flags & ~flags_bf.selector) | flags_bf.value;
 275         err = red_validate_flags(flags, extack);
 276         if (err)
 277                 goto unlock_out;
 278
 279         q->flags = flags;
 280         q->userbits = userbits;
 281         q->limit = ctl->limit;
 282         if (child) {
 283                 qdisc_tree_flush_backlog(q->qdisc);
 284                 old_child = q->qdisc;
 285                 q->qdisc = child;
 286         }
 287
 288         red_set_parms(&q->parms,
 289                       ctl->qth_min, ctl->qth_max, ctl->Wlog,
 290                       ctl->Plog, ctl->Scell_log,
 291                       nla_data(tb[TCA_RED_STAB]),
 292                       max_P);
 293         red_set_vars(&q->vars);
 294
 295         del_timer(&q->adapt_timer);
 296         if (ctl->flags & TC_RED_ADAPTATIVE)
 297                 mod_timer(&q->adapt_timer, jiffies + HZ/2);
 298
 299         if (!q->qdisc->q.qlen)
 300                 red_start_of_idle_period(&q->vars);
 301
 302         sch_tree_unlock(sch);
 303
 304         red_offload(sch, true);
 305
 306         if (old_child)
 307                 qdisc_put(old_child);
 308         return 0;
 309
 310 unlock_out:
 311         sch_tree_unlock(sch);
 312         if (child)
 313                 qdisc_put(child);
 314         return err;
 315 }
 316
 317 static inline void red_adaptative_timer(struct timer_list *t)
 318 {
 319         struct red_sched_data *q = from_timer(q, t, adapt_timer);
 320         struct Qdisc *sch = q->sch;
 321         spinlock_t *root_lock = qdisc_lock(qdisc_root_sleeping(sch));
 322
 323         spin_lock(root_lock);
 324         red_adaptative_algo(&q->parms, &q->vars);
 325         mod_timer(&q->adapt_timer, jiffies + HZ/2);
 326         spin_unlock(root_lock);
 327 }
 328
 329 static int red_init(struct Qdisc *sch, struct nlattr *opt,
 330                     struct netlink_ext_ack *extack)
 331 {
 332         struct red_sched_data *q = qdisc_priv(sch);
 333         struct nlattr *tb[TCA_RED_MAX + 1];
 334         int err;
 335
 336         q->qdisc = &noop_qdisc;
 337         q->sch = sch;
 338         timer_setup(&q->adapt_timer, red_adaptative_timer, 0);
 339
 340         if (!opt)
 341                 return -EINVAL;
 342
 343         err = nla_parse_nested_deprecated(tb, TCA_RED_MAX, opt, red_policy,
 344                                           extack);
 345         if (err < 0)
 346                 return err;
 347
 348         err = __red_change(sch, tb, extack);
 349         if (err)
 350                 return err;
 351
 352         err = tcf_qevent_init(&q->qe_early_drop, sch,
 353                               FLOW_BLOCK_BINDER_TYPE_RED_EARLY_DROP,
 354                               tb[TCA_RED_EARLY_DROP_BLOCK], extack);
 355         if (err)
 356                 goto err_early_drop_init;
 357
 358         err = tcf_qevent_init(&q->qe_mark, sch,
 359                               FLOW_BLOCK_BINDER_TYPE_RED_MARK,
 360                               tb[TCA_RED_MARK_BLOCK], extack);
 361         if (err)
 362                 goto err_mark_init;
 363
 364         return 0;
 365
 366 err_mark_init:
 367         tcf_qevent_destroy(&q->qe_early_drop, sch);
 368 err_early_drop_init:
 369         del_timer_sync(&q->adapt_timer);
 370         red_offload(sch, false);
 371         qdisc_put(q->qdisc);
 372         return err;
 373 }
 374
 375 static int red_change(struct Qdisc *sch, struct nlattr *opt,
 376                       struct netlink_ext_ack *extack)
 377 {
 378         struct red_sched_data *q = qdisc_priv(sch);
 379         struct nlattr *tb[TCA_RED_MAX + 1];
 380         int err;
 381
 382         if (!opt)
 383                 return -EINVAL;
 384
 385         err = nla_parse_nested_deprecated(tb, TCA_RED_MAX, opt, red_policy,
 386                                           extack);
 387         if (err < 0)
 388                 return err;
 389
 390         err = tcf_qevent_validate_change(&q->qe_early_drop,
 391                                          tb[TCA_RED_EARLY_DROP_BLOCK], extack);
 392         if (err)
 393                 return err;
 394
 395         err = tcf_qevent_validate_change(&q->qe_mark,
 396                                          tb[TCA_RED_MARK_BLOCK], extack);
 397         if (err)
 398                 return err;
 399
 400         return __red_change(sch, tb, extack);
 401 }
 402
 403 static int red_dump_offload_stats(struct Qdisc *sch)
 404 {
 405         struct tc_red_qopt_offload hw_stats = {
 406                 .command = TC_RED_STATS,
 407                 .handle = sch->handle,
 408                 .parent = sch->parent,
 409                 {
 410                         .stats.bstats = &sch->bstats,
 411                         .stats.qstats = &sch->qstats,
 412                 },
 413         };
 414
 415         return qdisc_offload_dump_helper(sch, TC_SETUP_QDISC_RED, &hw_stats);
 416 }
 417
 418 static int red_dump(struct Qdisc *sch, struct sk_buff *skb)
 419 {
 420         struct red_sched_data *q = qdisc_priv(sch);
 421         struct nlattr *opts = NULL;
 422         struct tc_red_qopt opt = {
 423                 .limit          = q->limit,
 424                 .flags          = (q->flags & TC_RED_HISTORIC_FLAGS) |
 425                                   q->userbits,
 426                 .qth_min        = q->parms.qth_min >> q->parms.Wlog,
 427                 .qth_max        = q->parms.qth_max >> q->parms.Wlog,
 428                 .Wlog           = q->parms.Wlog,
 429                 .Plog           = q->parms.Plog,
 430                 .Scell_log      = q->parms.Scell_log,
 431         };
 432         int err;
 433
 434         err = red_dump_offload_stats(sch);
 435         if (err)
 436                 goto nla_put_failure;
 437
 438         opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
 439         if (opts == NULL)
 440                 goto nla_put_failure;
 441         if (nla_put(skb, TCA_RED_PARMS, sizeof(opt), &opt) ||
 442             nla_put_u32(skb, TCA_RED_MAX_P, q->parms.max_P) ||
 443             nla_put_bitfield32(skb, TCA_RED_FLAGS,
 444                                q->flags, TC_RED_SUPPORTED_FLAGS) ||
 445             tcf_qevent_dump(skb, TCA_RED_MARK_BLOCK, &q->qe_mark) ||
 446             tcf_qevent_dump(skb, TCA_RED_EARLY_DROP_BLOCK, &q->qe_early_drop))
 447                 goto nla_put_failure;
 448         return nla_nest_end(skb, opts);
 449
 450 nla_put_failure:
 451         nla_nest_cancel(skb, opts);
 452         return -EMSGSIZE;
 453 }
 454
 455 static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 456 {
 457         struct red_sched_data *q = qdisc_priv(sch);
 458         struct net_device *dev = qdisc_dev(sch);
 459         struct tc_red_xstats st = {0};
 460
 461         if (sch->flags & TCQ_F_OFFLOADED) {
 462                 struct tc_red_qopt_offload hw_stats_request = {
 463                         .command = TC_RED_XSTATS,
 464                         .handle = sch->handle,
 465                         .parent = sch->parent,
 466                         {
 467                                 .xstats = &q->stats,
 468                         },
 469                 };
 470                 dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED,
 471                                               &hw_stats_request);
 472         }
 473         st.early = q->stats.prob_drop + q->stats.forced_drop;
 474         st.pdrop = q->stats.pdrop;
 475         st.other = q->stats.other;
 476         st.marked = q->stats.prob_mark + q->stats.forced_mark;
 477
 478         return gnet_stats_copy_app(d, &st, sizeof(st));
 479 }
 480
 481 static int red_dump_class(struct Qdisc *sch, unsigned long cl,
 482                           struct sk_buff *skb, struct tcmsg *tcm)
 483 {
 484         struct red_sched_data *q = qdisc_priv(sch);
 485
 486         tcm->tcm_handle |= TC_H_MIN(1);
 487         tcm->tcm_info = q->qdisc->handle;
 488         return 0;
 489 }
 490
 491 static void red_graft_offload(struct Qdisc *sch,
 492                               struct Qdisc *new, struct Qdisc *old,
 493                               struct netlink_ext_ack *extack)
 494 {
 495         struct tc_red_qopt_offload graft_offload = {
 496                 .handle         = sch->handle,
 497                 .parent         = sch->parent,
 498                 .child_handle   = new->handle,
 499                 .command        = TC_RED_GRAFT,
 500         };
 501
 502         qdisc_offload_graft_helper(qdisc_dev(sch), sch, new, old,
 503                                    TC_SETUP_QDISC_RED, &graft_offload, extack);
 504 }
 505
 506 static int red_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 507                      struct Qdisc **old, struct netlink_ext_ack *extack)
 508 {
 509         struct red_sched_data *q = qdisc_priv(sch);
 510
 511         if (new == NULL)
 512                 new = &noop_qdisc;
 513
 514         *old = qdisc_replace(sch, new, &q->qdisc);
 515
 516         red_graft_offload(sch, new, *old, extack);
 517         return 0;
 518 }
 519
 520 static struct Qdisc *red_leaf(struct Qdisc *sch, unsigned long arg)
 521 {
 522         struct red_sched_data *q = qdisc_priv(sch);
 523         return q->qdisc;
 524 }
 525
 526 static unsigned long red_find(struct Qdisc *sch, u32 classid)
 527 {
 528         return 1;
 529 }
 530
 531 static void red_walk(struct Qdisc *sch, struct qdisc_walker *walker)
 532 {
 533         if (!walker->stop) {
 534                 if (walker->count >= walker->skip)
 535                         if (walker->fn(sch, 1, walker) < 0) {
 536                                 walker->stop = 1;
 537                                 return;
 538                         }
 539                 walker->count++;
 540         }
 541 }
 542
 543 static const struct Qdisc_class_ops red_class_ops = {
 544         .graft          =       red_graft,
 545         .leaf           =       red_leaf,
 546         .find           =       red_find,
 547         .walk           =       red_walk,
 548         .dump           =       red_dump_class,
 549 };
 550
 551 static struct Qdisc_ops red_qdisc_ops __read_mostly = {
 552         .id             =       "red",
 553         .priv_size      =       sizeof(struct red_sched_data),
 554         .cl_ops         =       &red_class_ops,
 555         .enqueue        =       red_enqueue,
 556         .dequeue        =       red_dequeue,
 557         .peek           =       red_peek,
 558         .init           =       red_init,
 559         .reset          =       red_reset,
 560         .destroy        =       red_destroy,
 561         .change         =       red_change,
 562         .dump           =       red_dump,
 563         .dump_stats     =       red_dump_stats,
 564         .owner          =       THIS_MODULE,
 565 };
 566
 567 static int __init red_module_init(void)
 568 {
 569         return register_qdisc(&red_qdisc_ops);
 570 }
 571
 572 static void __exit red_module_exit(void)
 573 {
 574         unregister_qdisc(&red_qdisc_ops);
 575 }
 576
 577 module_init(red_module_init)
 578 module_exit(red_module_exit)
 579
 580 MODULE_LICENSE("GPL");