net/sched/sch_red.c

   1 /*
   2  * net/sched/sch_red.c  Random Early Detection queue.
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  *
  11  * Changes:
  12  * J Hadi Salim 980914: computation fixes
  13  * Alexey Makarenko <makar@phoenix.kharkov.ua> 990814: qave on idle link was calculated incorrectly.
  14  * J Hadi Salim 980816:  ECN support
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/types.h>
  19 #include <linux/kernel.h>
  20 #include <linux/skbuff.h>
  21 #include <net/pkt_sched.h>
  22 #include <net/pkt_cls.h>
  23 #include <net/inet_ecn.h>
  24 #include <net/red.h>
  25
  26
  27 /*      Parameters, settable by user:
  28         -----------------------------
  29
  30         limit           - bytes (must be > qth_max + burst)
  31
  32         Hard limit on queue length, should be chosen >qth_max
  33         to allow packet bursts. This parameter does not
  34         affect the algorithms behaviour and can be chosen
  35         arbitrarily high (well, less than ram size)
  36         Really, this limit will never be reached
  37         if RED works correctly.
  38  */
  39
  40 struct red_sched_data {
  41         u32                     limit;          /* HARD maximal queue length */
  42         unsigned char           flags;
  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 };
  50
  51 static inline int red_use_ecn(struct red_sched_data *q)
  52 {
  53         return q->flags & TC_RED_ECN;
  54 }
  55
  56 static inline int red_use_harddrop(struct red_sched_data *q)
  57 {
  58         return q->flags & TC_RED_HARDDROP;
  59 }
  60
  61 static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch,
  62                        struct sk_buff **to_free)
  63 {
  64         struct red_sched_data *q = qdisc_priv(sch);
  65         struct Qdisc *child = q->qdisc;
  66         int ret;
  67
  68         q->vars.qavg = red_calc_qavg(&q->parms,
  69                                      &q->vars,
  70                                      child->qstats.backlog);
  71
  72         if (red_is_idling(&q->vars))
  73                 red_end_of_idle_period(&q->vars);
  74
  75         switch (red_action(&q->parms, &q->vars, q->vars.qavg)) {
  76         case RED_DONT_MARK:
  77                 break;
  78
  79         case RED_PROB_MARK:
  80                 qdisc_qstats_overlimit(sch);
  81                 if (!red_use_ecn(q) || !INET_ECN_set_ce(skb)) {
  82                         q->stats.prob_drop++;
  83                         goto congestion_drop;
  84                 }
  85
  86                 q->stats.prob_mark++;
  87                 break;
  88
  89         case RED_HARD_MARK:
  90                 qdisc_qstats_overlimit(sch);
  91                 if (red_use_harddrop(q) || !red_use_ecn(q) ||
  92                     !INET_ECN_set_ce(skb)) {
  93                         q->stats.forced_drop++;
  94                         goto congestion_drop;
  95                 }
  96
  97                 q->stats.forced_mark++;
  98                 break;
  99         }
 100
 101         ret = qdisc_enqueue(skb, child, to_free);
 102         if (likely(ret == NET_XMIT_SUCCESS)) {
 103                 qdisc_qstats_backlog_inc(sch, skb);
 104                 sch->q.qlen++;
 105         } else if (net_xmit_drop_count(ret)) {
 106                 q->stats.pdrop++;
 107                 qdisc_qstats_drop(sch);
 108         }
 109         return ret;
 110
 111 congestion_drop:
 112         qdisc_drop(skb, sch, to_free);
 113         return NET_XMIT_CN;
 114 }
 115
 116 static struct sk_buff *red_dequeue(struct Qdisc *sch)
 117 {
 118         struct sk_buff *skb;
 119         struct red_sched_data *q = qdisc_priv(sch);
 120         struct Qdisc *child = q->qdisc;
 121
 122         skb = child->dequeue(child);
 123         if (skb) {
 124                 qdisc_bstats_update(sch, skb);
 125                 qdisc_qstats_backlog_dec(sch, skb);
 126                 sch->q.qlen--;
 127         } else {
 128                 if (!red_is_idling(&q->vars))
 129                         red_start_of_idle_period(&q->vars);
 130         }
 131         return skb;
 132 }
 133
 134 static struct sk_buff *red_peek(struct Qdisc *sch)
 135 {
 136         struct red_sched_data *q = qdisc_priv(sch);
 137         struct Qdisc *child = q->qdisc;
 138
 139         return child->ops->peek(child);
 140 }
 141
 142 static void red_reset(struct Qdisc *sch)
 143 {
 144         struct red_sched_data *q = qdisc_priv(sch);
 145
 146         qdisc_reset(q->qdisc);
 147         sch->qstats.backlog = 0;
 148         sch->q.qlen = 0;
 149         red_restart(&q->vars);
 150 }
 151
 152 static int red_offload(struct Qdisc *sch, bool enable)
 153 {
 154         struct red_sched_data *q = qdisc_priv(sch);
 155         struct net_device *dev = qdisc_dev(sch);
 156         struct tc_red_qopt_offload opt = {
 157                 .handle = sch->handle,
 158                 .parent = sch->parent,
 159         };
 160
 161         if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc)
 162                 return -EOPNOTSUPP;
 163
 164         if (enable) {
 165                 opt.command = TC_RED_REPLACE;
 166                 opt.set.min = q->parms.qth_min >> q->parms.Wlog;
 167                 opt.set.max = q->parms.qth_max >> q->parms.Wlog;
 168                 opt.set.probability = q->parms.max_P;
 169                 opt.set.is_ecn = red_use_ecn(q);
 170         } else {
 171                 opt.command = TC_RED_DESTROY;
 172         }
 173
 174         return dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED, &opt);
 175 }
 176
 177 static void red_destroy(struct Qdisc *sch)
 178 {
 179         struct red_sched_data *q = qdisc_priv(sch);
 180
 181         del_timer_sync(&q->adapt_timer);
 182         red_offload(sch, false);
 183         qdisc_destroy(q->qdisc);
 184 }
 185
 186 static const struct nla_policy red_policy[TCA_RED_MAX + 1] = {
 187         [TCA_RED_PARMS] = { .len = sizeof(struct tc_red_qopt) },
 188         [TCA_RED_STAB]  = { .len = RED_STAB_SIZE },
 189         [TCA_RED_MAX_P] = { .type = NLA_U32 },
 190 };
 191
 192 static int red_change(struct Qdisc *sch, struct nlattr *opt)
 193 {
 194         struct red_sched_data *q = qdisc_priv(sch);
 195         struct nlattr *tb[TCA_RED_MAX + 1];
 196         struct tc_red_qopt *ctl;
 197         struct Qdisc *child = NULL;
 198         int err;
 199         u32 max_P;
 200
 201         if (opt == NULL)
 202                 return -EINVAL;
 203
 204         err = nla_parse_nested(tb, TCA_RED_MAX, opt, red_policy, NULL);
 205         if (err < 0)
 206                 return err;
 207
 208         if (tb[TCA_RED_PARMS] == NULL ||
 209             tb[TCA_RED_STAB] == NULL)
 210                 return -EINVAL;
 211
 212         max_P = tb[TCA_RED_MAX_P] ? nla_get_u32(tb[TCA_RED_MAX_P]) : 0;
 213
 214         ctl = nla_data(tb[TCA_RED_PARMS]);
 215         if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog))
 216                 return -EINVAL;
 217
 218         if (ctl->limit > 0) {
 219                 child = fifo_create_dflt(sch, &bfifo_qdisc_ops, ctl->limit);
 220                 if (IS_ERR(child))
 221                         return PTR_ERR(child);
 222         }
 223
 224         if (child != &noop_qdisc)
 225                 qdisc_hash_add(child, true);
 226         sch_tree_lock(sch);
 227         q->flags = ctl->flags;
 228         q->limit = ctl->limit;
 229         if (child) {
 230                 qdisc_tree_reduce_backlog(q->qdisc, q->qdisc->q.qlen,
 231                                           q->qdisc->qstats.backlog);
 232                 qdisc_destroy(q->qdisc);
 233                 q->qdisc = child;
 234         }
 235
 236         red_set_parms(&q->parms,
 237                       ctl->qth_min, ctl->qth_max, ctl->Wlog,
 238                       ctl->Plog, ctl->Scell_log,
 239                       nla_data(tb[TCA_RED_STAB]),
 240                       max_P);
 241         red_set_vars(&q->vars);
 242
 243         del_timer(&q->adapt_timer);
 244         if (ctl->flags & TC_RED_ADAPTATIVE)
 245                 mod_timer(&q->adapt_timer, jiffies + HZ/2);
 246
 247         if (!q->qdisc->q.qlen)
 248                 red_start_of_idle_period(&q->vars);
 249
 250         sch_tree_unlock(sch);
 251         red_offload(sch, true);
 252         return 0;
 253 }
 254
 255 static inline void red_adaptative_timer(struct timer_list *t)
 256 {
 257         struct red_sched_data *q = from_timer(q, t, adapt_timer);
 258         struct Qdisc *sch = q->sch;
 259         spinlock_t *root_lock = qdisc_lock(qdisc_root_sleeping(sch));
 260
 261         spin_lock(root_lock);
 262         red_adaptative_algo(&q->parms, &q->vars);
 263         mod_timer(&q->adapt_timer, jiffies + HZ/2);
 264         spin_unlock(root_lock);
 265 }
 266
 267 static int red_init(struct Qdisc *sch, struct nlattr *opt)
 268 {
 269         struct red_sched_data *q = qdisc_priv(sch);
 270
 271         q->qdisc = &noop_qdisc;
 272         q->sch = sch;
 273         timer_setup(&q->adapt_timer, red_adaptative_timer, 0);
 274         return red_change(sch, opt);
 275 }
 276
 277 static int red_dump_offload_stats(struct Qdisc *sch, struct tc_red_qopt *opt)
 278 {
 279         struct net_device *dev = qdisc_dev(sch);
 280         struct tc_red_qopt_offload hw_stats = {
 281                 .command = TC_RED_STATS,
 282                 .handle = sch->handle,
 283                 .parent = sch->parent,
 284                 {
 285                         .stats.bstats = &sch->bstats,
 286                         .stats.qstats = &sch->qstats,
 287                 },
 288         };
 289         int err;
 290
 291         sch->flags &= ~TCQ_F_OFFLOADED;
 292
 293         if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc)
 294                 return 0;
 295
 296         err = dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED,
 297                                             &hw_stats);
 298         if (err == -EOPNOTSUPP)
 299                 return 0;
 300
 301         if (!err)
 302                 sch->flags |= TCQ_F_OFFLOADED;
 303
 304         return err;
 305 }
 306
 307 static int red_dump(struct Qdisc *sch, struct sk_buff *skb)
 308 {
 309         struct red_sched_data *q = qdisc_priv(sch);
 310         struct nlattr *opts = NULL;
 311         struct tc_red_qopt opt = {
 312                 .limit          = q->limit,
 313                 .flags          = q->flags,
 314                 .qth_min        = q->parms.qth_min >> q->parms.Wlog,
 315                 .qth_max        = q->parms.qth_max >> q->parms.Wlog,
 316                 .Wlog           = q->parms.Wlog,
 317                 .Plog           = q->parms.Plog,
 318                 .Scell_log      = q->parms.Scell_log,
 319         };
 320         int err;
 321
 322         sch->qstats.backlog = q->qdisc->qstats.backlog;
 323         err = red_dump_offload_stats(sch, &opt);
 324         if (err)
 325                 goto nla_put_failure;
 326
 327         opts = nla_nest_start(skb, TCA_OPTIONS);
 328         if (opts == NULL)
 329                 goto nla_put_failure;
 330         if (nla_put(skb, TCA_RED_PARMS, sizeof(opt), &opt) ||
 331             nla_put_u32(skb, TCA_RED_MAX_P, q->parms.max_P))
 332                 goto nla_put_failure;
 333         return nla_nest_end(skb, opts);
 334
 335 nla_put_failure:
 336         nla_nest_cancel(skb, opts);
 337         return -EMSGSIZE;
 338 }
 339
 340 static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 341 {
 342         struct red_sched_data *q = qdisc_priv(sch);
 343         struct net_device *dev = qdisc_dev(sch);
 344         struct tc_red_xstats st = {
 345                 .early  = q->stats.prob_drop + q->stats.forced_drop,
 346                 .pdrop  = q->stats.pdrop,
 347                 .other  = q->stats.other,
 348                 .marked = q->stats.prob_mark + q->stats.forced_mark,
 349         };
 350
 351         if (sch->flags & TCQ_F_OFFLOADED) {
 352                 struct red_stats hw_stats = {0};
 353                 struct tc_red_qopt_offload hw_stats_request = {
 354                         .command = TC_RED_XSTATS,
 355                         .handle = sch->handle,
 356                         .parent = sch->parent,
 357                         {
 358                                 .xstats = &hw_stats,
 359                         },
 360                 };
 361                 if (!dev->netdev_ops->ndo_setup_tc(dev,
 362                                                    TC_SETUP_QDISC_RED,
 363                                                    &hw_stats_request)) {
 364                         st.early += hw_stats.prob_drop + hw_stats.forced_drop;
 365                         st.pdrop += hw_stats.pdrop;
 366                         st.other += hw_stats.other;
 367                         st.marked += hw_stats.prob_mark + hw_stats.forced_mark;
 368                 }
 369         }
 370
 371         return gnet_stats_copy_app(d, &st, sizeof(st));
 372 }
 373
 374 static int red_dump_class(struct Qdisc *sch, unsigned long cl,
 375                           struct sk_buff *skb, struct tcmsg *tcm)
 376 {
 377         struct red_sched_data *q = qdisc_priv(sch);
 378
 379         tcm->tcm_handle |= TC_H_MIN(1);
 380         tcm->tcm_info = q->qdisc->handle;
 381         return 0;
 382 }
 383
 384 static int red_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 385                      struct Qdisc **old)
 386 {
 387         struct red_sched_data *q = qdisc_priv(sch);
 388
 389         if (new == NULL)
 390                 new = &noop_qdisc;
 391
 392         *old = qdisc_replace(sch, new, &q->qdisc);
 393         return 0;
 394 }
 395
 396 static struct Qdisc *red_leaf(struct Qdisc *sch, unsigned long arg)
 397 {
 398         struct red_sched_data *q = qdisc_priv(sch);
 399         return q->qdisc;
 400 }
 401
 402 static unsigned long red_find(struct Qdisc *sch, u32 classid)
 403 {
 404         return 1;
 405 }
 406
 407 static void red_walk(struct Qdisc *sch, struct qdisc_walker *walker)
 408 {
 409         if (!walker->stop) {
 410                 if (walker->count >= walker->skip)
 411                         if (walker->fn(sch, 1, walker) < 0) {
 412                                 walker->stop = 1;
 413                                 return;
 414                         }
 415                 walker->count++;
 416         }
 417 }
 418
 419 static const struct Qdisc_class_ops red_class_ops = {
 420         .graft          =       red_graft,
 421         .leaf           =       red_leaf,
 422         .find           =       red_find,
 423         .walk           =       red_walk,
 424         .dump           =       red_dump_class,
 425 };
 426
 427 static struct Qdisc_ops red_qdisc_ops __read_mostly = {
 428         .id             =       "red",
 429         .priv_size      =       sizeof(struct red_sched_data),
 430         .cl_ops         =       &red_class_ops,
 431         .enqueue        =       red_enqueue,
 432         .dequeue        =       red_dequeue,
 433         .peek           =       red_peek,
 434         .init           =       red_init,
 435         .reset          =       red_reset,
 436         .destroy        =       red_destroy,
 437         .change         =       red_change,
 438         .dump           =       red_dump,
 439         .dump_stats     =       red_dump_stats,
 440         .owner          =       THIS_MODULE,
 441 };
 442
 443 static int __init red_module_init(void)
 444 {
 445         return register_qdisc(&red_qdisc_ops);
 446 }
 447
 448 static void __exit red_module_exit(void)
 449 {
 450         unregister_qdisc(&red_qdisc_ops);
 451 }
 452
 453 module_init(red_module_init)
 454 module_exit(red_module_exit)
 455
 456 MODULE_LICENSE("GPL");