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         unsigned int len;
  76         int ret;
  77
  78         q->vars.qavg = red_calc_qavg(&q->parms,
  79                                      &q->vars,
  80                                      child->qstats.backlog);
  81
  82         if (red_is_idling(&q->vars))
  83                 red_end_of_idle_period(&q->vars);
  84
  85         switch (red_action(&q->parms, &q->vars, q->vars.qavg)) {
  86         case RED_DONT_MARK:
  87                 break;
  88
  89         case RED_PROB_MARK:
  90                 qdisc_qstats_overlimit(sch);
  91                 if (!red_use_ecn(q)) {
  92                         q->stats.prob_drop++;
  93                         goto congestion_drop;
  94                 }
  95
  96                 if (INET_ECN_set_ce(skb)) {
  97                         q->stats.prob_mark++;
  98                         skb = tcf_qevent_handle(&q->qe_mark, sch, skb, to_free, &ret);
  99                         if (!skb)
 100                                 return NET_XMIT_CN | ret;
 101                 } else if (!red_use_nodrop(q)) {
 102                         q->stats.prob_drop++;
 103                         goto congestion_drop;
 104                 }
 105
 106                 /* Non-ECT packet in ECN nodrop mode: queue it. */
 107                 break;
 108
 109         case RED_HARD_MARK:
 110                 qdisc_qstats_overlimit(sch);
 111                 if (red_use_harddrop(q) || !red_use_ecn(q)) {
 112                         q->stats.forced_drop++;
 113                         goto congestion_drop;
 114                 }
 115
 116                 if (INET_ECN_set_ce(skb)) {
 117                         q->stats.forced_mark++;
 118                         skb = tcf_qevent_handle(&q->qe_mark, sch, skb, to_free, &ret);
 119                         if (!skb)
 120                                 return NET_XMIT_CN | ret;
 121                 } else if (!red_use_nodrop(q)) {
 122                         q->stats.forced_drop++;
 123                         goto congestion_drop;
 124                 }
 125
 126                 /* Non-ECT packet in ECN nodrop mode: queue it. */
 127                 break;
 128         }
 129
 130         len = qdisc_pkt_len(skb);
 131         ret = qdisc_enqueue(skb, child, to_free);
 132         if (likely(ret == NET_XMIT_SUCCESS)) {
 133                 sch->qstats.backlog += len;
 134                 sch->q.qlen++;
 135         } else if (net_xmit_drop_count(ret)) {
 136                 q->stats.pdrop++;
 137                 qdisc_qstats_drop(sch);
 138         }
 139         return ret;
 140
 141 congestion_drop:
 142         skb = tcf_qevent_handle(&q->qe_early_drop, sch, skb, to_free, &ret);
 143         if (!skb)
 144                 return NET_XMIT_CN | ret;
 145
 146         qdisc_drop(skb, sch, to_free);
 147         return NET_XMIT_CN;
 148 }
 149
 150 static struct sk_buff *red_dequeue(struct Qdisc *sch)
 151 {
 152         struct sk_buff *skb;
 153         struct red_sched_data *q = qdisc_priv(sch);
 154         struct Qdisc *child = q->qdisc;
 155
 156         skb = child->dequeue(child);
 157         if (skb) {
 158                 qdisc_bstats_update(sch, skb);
 159                 qdisc_qstats_backlog_dec(sch, skb);
 160                 sch->q.qlen--;
 161         } else {
 162                 if (!red_is_idling(&q->vars))
 163                         red_start_of_idle_period(&q->vars);
 164         }
 165         return skb;
 166 }
 167
 168 static struct sk_buff *red_peek(struct Qdisc *sch)
 169 {
 170         struct red_sched_data *q = qdisc_priv(sch);
 171         struct Qdisc *child = q->qdisc;
 172
 173         return child->ops->peek(child);
 174 }
 175
 176 static void red_reset(struct Qdisc *sch)
 177 {
 178         struct red_sched_data *q = qdisc_priv(sch);
 179
 180         qdisc_reset(q->qdisc);
 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         u8 *stab;
 246
 247         if (tb[TCA_RED_PARMS] == NULL ||
 248             tb[TCA_RED_STAB] == NULL)
 249                 return -EINVAL;
 250
 251         max_P = tb[TCA_RED_MAX_P] ? nla_get_u32(tb[TCA_RED_MAX_P]) : 0;
 252
 253         ctl = nla_data(tb[TCA_RED_PARMS]);
 254         stab = nla_data(tb[TCA_RED_STAB]);
 255         if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog,
 256                               ctl->Scell_log, stab))
 257                 return -EINVAL;
 258
 259         err = red_get_flags(ctl->flags, TC_RED_HISTORIC_FLAGS,
 260                             tb[TCA_RED_FLAGS], TC_RED_SUPPORTED_FLAGS,
 261                             &flags_bf, &userbits, extack);
 262         if (err)
 263                 return err;
 264
 265         if (ctl->limit > 0) {
 266                 child = fifo_create_dflt(sch, &bfifo_qdisc_ops, ctl->limit,
 267                                          extack);
 268                 if (IS_ERR(child))
 269                         return PTR_ERR(child);
 270
 271                 /* child is fifo, no need to check for noop_qdisc */
 272                 qdisc_hash_add(child, true);
 273         }
 274
 275         sch_tree_lock(sch);
 276
 277         flags = (q->flags & ~flags_bf.selector) | flags_bf.value;
 278         err = red_validate_flags(flags, extack);
 279         if (err)
 280                 goto unlock_out;
 281
 282         q->flags = flags;
 283         q->userbits = userbits;
 284         q->limit = ctl->limit;
 285         if (child) {
 286                 qdisc_tree_flush_backlog(q->qdisc);
 287                 old_child = q->qdisc;
 288                 q->qdisc = child;
 289         }
 290
 291         red_set_parms(&q->parms,
 292                       ctl->qth_min, ctl->qth_max, ctl->Wlog,
 293                       ctl->Plog, ctl->Scell_log,
 294                       stab,
 295                       max_P);
 296         red_set_vars(&q->vars);
 297
 298         del_timer(&q->adapt_timer);
 299         if (ctl->flags & TC_RED_ADAPTATIVE)
 300                 mod_timer(&q->adapt_timer, jiffies + HZ/2);
 301
 302         if (!q->qdisc->q.qlen)
 303                 red_start_of_idle_period(&q->vars);
 304
 305         sch_tree_unlock(sch);
 306
 307         red_offload(sch, true);
 308
 309         if (old_child)
 310                 qdisc_put(old_child);
 311         return 0;
 312
 313 unlock_out:
 314         sch_tree_unlock(sch);
 315         if (child)
 316                 qdisc_put(child);
 317         return err;
 318 }
 319
 320 static inline void red_adaptative_timer(struct timer_list *t)
 321 {
 322         struct red_sched_data *q = from_timer(q, t, adapt_timer);
 323         struct Qdisc *sch = q->sch;
 324         spinlock_t *root_lock = qdisc_lock(qdisc_root_sleeping(sch));
 325
 326         spin_lock(root_lock);
 327         red_adaptative_algo(&q->parms, &q->vars);
 328         mod_timer(&q->adapt_timer, jiffies + HZ/2);
 329         spin_unlock(root_lock);
 330 }
 331
 332 static int red_init(struct Qdisc *sch, struct nlattr *opt,
 333                     struct netlink_ext_ack *extack)
 334 {
 335         struct red_sched_data *q = qdisc_priv(sch);
 336         struct nlattr *tb[TCA_RED_MAX + 1];
 337         int err;
 338
 339         q->qdisc = &noop_qdisc;
 340         q->sch = sch;
 341         timer_setup(&q->adapt_timer, red_adaptative_timer, 0);
 342
 343         if (!opt)
 344                 return -EINVAL;
 345
 346         err = nla_parse_nested_deprecated(tb, TCA_RED_MAX, opt, red_policy,
 347                                           extack);
 348         if (err < 0)
 349                 return err;
 350
 351         err = __red_change(sch, tb, extack);
 352         if (err)
 353                 return err;
 354
 355         err = tcf_qevent_init(&q->qe_early_drop, sch,
 356                               FLOW_BLOCK_BINDER_TYPE_RED_EARLY_DROP,
 357                               tb[TCA_RED_EARLY_DROP_BLOCK], extack);
 358         if (err)
 359                 return err;
 360
 361         return tcf_qevent_init(&q->qe_mark, sch,
 362                                FLOW_BLOCK_BINDER_TYPE_RED_MARK,
 363                                tb[TCA_RED_MARK_BLOCK], extack);
 364 }
 365
 366 static int red_change(struct Qdisc *sch, struct nlattr *opt,
 367                       struct netlink_ext_ack *extack)
 368 {
 369         struct red_sched_data *q = qdisc_priv(sch);
 370         struct nlattr *tb[TCA_RED_MAX + 1];
 371         int err;
 372
 373         err = nla_parse_nested_deprecated(tb, TCA_RED_MAX, opt, red_policy,
 374                                           extack);
 375         if (err < 0)
 376                 return err;
 377
 378         err = tcf_qevent_validate_change(&q->qe_early_drop,
 379                                          tb[TCA_RED_EARLY_DROP_BLOCK], extack);
 380         if (err)
 381                 return err;
 382
 383         err = tcf_qevent_validate_change(&q->qe_mark,
 384                                          tb[TCA_RED_MARK_BLOCK], extack);
 385         if (err)
 386                 return err;
 387
 388         return __red_change(sch, tb, extack);
 389 }
 390
 391 static int red_dump_offload_stats(struct Qdisc *sch)
 392 {
 393         struct tc_red_qopt_offload hw_stats = {
 394                 .command = TC_RED_STATS,
 395                 .handle = sch->handle,
 396                 .parent = sch->parent,
 397                 {
 398                         .stats.bstats = &sch->bstats,
 399                         .stats.qstats = &sch->qstats,
 400                 },
 401         };
 402
 403         return qdisc_offload_dump_helper(sch, TC_SETUP_QDISC_RED, &hw_stats);
 404 }
 405
 406 static int red_dump(struct Qdisc *sch, struct sk_buff *skb)
 407 {
 408         struct red_sched_data *q = qdisc_priv(sch);
 409         struct nlattr *opts = NULL;
 410         struct tc_red_qopt opt = {
 411                 .limit          = q->limit,
 412                 .flags          = (q->flags & TC_RED_HISTORIC_FLAGS) |
 413                                   q->userbits,
 414                 .qth_min        = q->parms.qth_min >> q->parms.Wlog,
 415                 .qth_max        = q->parms.qth_max >> q->parms.Wlog,
 416                 .Wlog           = q->parms.Wlog,
 417                 .Plog           = q->parms.Plog,
 418                 .Scell_log      = q->parms.Scell_log,
 419         };
 420         int err;
 421
 422         err = red_dump_offload_stats(sch);
 423         if (err)
 424                 goto nla_put_failure;
 425
 426         opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
 427         if (opts == NULL)
 428                 goto nla_put_failure;
 429         if (nla_put(skb, TCA_RED_PARMS, sizeof(opt), &opt) ||
 430             nla_put_u32(skb, TCA_RED_MAX_P, q->parms.max_P) ||
 431             nla_put_bitfield32(skb, TCA_RED_FLAGS,
 432                                q->flags, TC_RED_SUPPORTED_FLAGS) ||
 433             tcf_qevent_dump(skb, TCA_RED_MARK_BLOCK, &q->qe_mark) ||
 434             tcf_qevent_dump(skb, TCA_RED_EARLY_DROP_BLOCK, &q->qe_early_drop))
 435                 goto nla_put_failure;
 436         return nla_nest_end(skb, opts);
 437
 438 nla_put_failure:
 439         nla_nest_cancel(skb, opts);
 440         return -EMSGSIZE;
 441 }
 442
 443 static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 444 {
 445         struct red_sched_data *q = qdisc_priv(sch);
 446         struct net_device *dev = qdisc_dev(sch);
 447         struct tc_red_xstats st = {0};
 448
 449         if (sch->flags & TCQ_F_OFFLOADED) {
 450                 struct tc_red_qopt_offload hw_stats_request = {
 451                         .command = TC_RED_XSTATS,
 452                         .handle = sch->handle,
 453                         .parent = sch->parent,
 454                         {
 455                                 .xstats = &q->stats,
 456                         },
 457                 };
 458                 dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED,
 459                                               &hw_stats_request);
 460         }
 461         st.early = q->stats.prob_drop + q->stats.forced_drop;
 462         st.pdrop = q->stats.pdrop;
 463         st.marked = q->stats.prob_mark + q->stats.forced_mark;
 464
 465         return gnet_stats_copy_app(d, &st, sizeof(st));
 466 }
 467
 468 static int red_dump_class(struct Qdisc *sch, unsigned long cl,
 469                           struct sk_buff *skb, struct tcmsg *tcm)
 470 {
 471         struct red_sched_data *q = qdisc_priv(sch);
 472
 473         tcm->tcm_handle |= TC_H_MIN(1);
 474         tcm->tcm_info = q->qdisc->handle;
 475         return 0;
 476 }
 477
 478 static void red_graft_offload(struct Qdisc *sch,
 479                               struct Qdisc *new, struct Qdisc *old,
 480                               struct netlink_ext_ack *extack)
 481 {
 482         struct tc_red_qopt_offload graft_offload = {
 483                 .handle         = sch->handle,
 484                 .parent         = sch->parent,
 485                 .child_handle   = new->handle,
 486                 .command        = TC_RED_GRAFT,
 487         };
 488
 489         qdisc_offload_graft_helper(qdisc_dev(sch), sch, new, old,
 490                                    TC_SETUP_QDISC_RED, &graft_offload, extack);
 491 }
 492
 493 static int red_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 494                      struct Qdisc **old, struct netlink_ext_ack *extack)
 495 {
 496         struct red_sched_data *q = qdisc_priv(sch);
 497
 498         if (new == NULL)
 499                 new = &noop_qdisc;
 500
 501         *old = qdisc_replace(sch, new, &q->qdisc);
 502
 503         red_graft_offload(sch, new, *old, extack);
 504         return 0;
 505 }
 506
 507 static struct Qdisc *red_leaf(struct Qdisc *sch, unsigned long arg)
 508 {
 509         struct red_sched_data *q = qdisc_priv(sch);
 510         return q->qdisc;
 511 }
 512
 513 static unsigned long red_find(struct Qdisc *sch, u32 classid)
 514 {
 515         return 1;
 516 }
 517
 518 static void red_walk(struct Qdisc *sch, struct qdisc_walker *walker)
 519 {
 520         if (!walker->stop) {
 521                 tc_qdisc_stats_dump(sch, 1, walker);
 522         }
 523 }
 524
 525 static const struct Qdisc_class_ops red_class_ops = {
 526         .graft          =       red_graft,
 527         .leaf           =       red_leaf,
 528         .find           =       red_find,
 529         .walk           =       red_walk,
 530         .dump           =       red_dump_class,
 531 };
 532
 533 static struct Qdisc_ops red_qdisc_ops __read_mostly = {
 534         .id             =       "red",
 535         .priv_size      =       sizeof(struct red_sched_data),
 536         .cl_ops         =       &red_class_ops,
 537         .enqueue        =       red_enqueue,
 538         .dequeue        =       red_dequeue,
 539         .peek           =       red_peek,
 540         .init           =       red_init,
 541         .reset          =       red_reset,
 542         .destroy        =       red_destroy,
 543         .change         =       red_change,
 544         .dump           =       red_dump,
 545         .dump_stats     =       red_dump_stats,
 546         .owner          =       THIS_MODULE,
 547 };
 548
 549 static int __init red_module_init(void)
 550 {
 551         return register_qdisc(&red_qdisc_ops);
 552 }
 553
 554 static void __exit red_module_exit(void)
 555 {
 556         unregister_qdisc(&red_qdisc_ops);
 557 }
 558
 559 module_init(red_module_init)
 560 module_exit(red_module_exit)
 561
 562 MODULE_LICENSE("GPL");