net/sched/sch_gred.c

   1 /*
   2  * net/sched/sch_gred.c Generic Random Early Detection queue.
   3  *
   4  *
   5  *              This program is free software; you can redistribute it and/or
   6  *              modify it under the terms of the GNU General Public License
   7  *              as published by the Free Software Foundation; either version
   8  *              2 of the License, or (at your option) any later version.
   9  *
  10  * Authors:    J Hadi Salim (hadi@cyberus.ca) 1998-2002
  11  *
  12  *             991129: -  Bug fix with grio mode
  13  *                     - a better sing. AvgQ mode with Grio(WRED)
  14  *                     - A finer grained VQ dequeue based on sugestion
  15  *                       from Ren Liu
  16  *                     - More error checks
  17  *
  18  *  For all the glorious comments look at include/net/red.h
  19  */
  20
  21 #include <linux/slab.h>
  22 #include <linux/module.h>
  23 #include <linux/types.h>
  24 #include <linux/kernel.h>
  25 #include <linux/skbuff.h>
  26 #include <net/pkt_sched.h>
  27 #include <net/red.h>
  28
  29 #define GRED_DEF_PRIO (MAX_DPs / 2)
  30 #define GRED_VQ_MASK (MAX_DPs - 1)
  31
  32 struct gred_sched_data;
  33 struct gred_sched;
  34
  35 struct gred_sched_data {
  36         u32             limit;          /* HARD maximal queue length    */
  37         u32             DP;             /* the drop parameters */
  38         u32             bytesin;        /* bytes seen on virtualQ so far*/
  39         u32             packetsin;      /* packets seen on virtualQ so far*/
  40         u32             backlog;        /* bytes on the virtualQ */
  41         u8              prio;           /* the prio of this vq */
  42
  43         struct red_parms parms;
  44         struct red_vars  vars;
  45         struct red_stats stats;
  46 };
  47
  48 enum {
  49         GRED_WRED_MODE = 1,
  50         GRED_RIO_MODE,
  51 };
  52
  53 struct gred_sched {
  54         struct gred_sched_data *tab[MAX_DPs];
  55         unsigned long   flags;
  56         u32             red_flags;
  57         u32             DPs;
  58         u32             def;
  59         struct red_vars wred_set;
  60 };
  61
  62 static inline int gred_wred_mode(struct gred_sched *table)
  63 {
  64         return test_bit(GRED_WRED_MODE, &table->flags);
  65 }
  66
  67 static inline void gred_enable_wred_mode(struct gred_sched *table)
  68 {
  69         __set_bit(GRED_WRED_MODE, &table->flags);
  70 }
  71
  72 static inline void gred_disable_wred_mode(struct gred_sched *table)
  73 {
  74         __clear_bit(GRED_WRED_MODE, &table->flags);
  75 }
  76
  77 static inline int gred_rio_mode(struct gred_sched *table)
  78 {
  79         return test_bit(GRED_RIO_MODE, &table->flags);
  80 }
  81
  82 static inline void gred_enable_rio_mode(struct gred_sched *table)
  83 {
  84         __set_bit(GRED_RIO_MODE, &table->flags);
  85 }
  86
  87 static inline void gred_disable_rio_mode(struct gred_sched *table)
  88 {
  89         __clear_bit(GRED_RIO_MODE, &table->flags);
  90 }
  91
  92 static inline int gred_wred_mode_check(struct Qdisc *sch)
  93 {
  94         struct gred_sched *table = qdisc_priv(sch);
  95         int i;
  96
  97         /* Really ugly O(n^2) but shouldn't be necessary too frequent. */
  98         for (i = 0; i < table->DPs; i++) {
  99                 struct gred_sched_data *q = table->tab[i];
 100                 int n;
 101
 102                 if (q == NULL)
 103                         continue;
 104
 105                 for (n = i + 1; n < table->DPs; n++)
 106                         if (table->tab[n] && table->tab[n]->prio == q->prio)
 107                                 return 1;
 108         }
 109
 110         return 0;
 111 }
 112
 113 static inline unsigned int gred_backlog(struct gred_sched *table,
 114                                         struct gred_sched_data *q,
 115                                         struct Qdisc *sch)
 116 {
 117         if (gred_wred_mode(table))
 118                 return sch->qstats.backlog;
 119         else
 120                 return q->backlog;
 121 }
 122
 123 static inline u16 tc_index_to_dp(struct sk_buff *skb)
 124 {
 125         return skb->tc_index & GRED_VQ_MASK;
 126 }
 127
 128 static inline void gred_load_wred_set(const struct gred_sched *table,
 129                                       struct gred_sched_data *q)
 130 {
 131         q->vars.qavg = table->wred_set.qavg;
 132         q->vars.qidlestart = table->wred_set.qidlestart;
 133 }
 134
 135 static inline void gred_store_wred_set(struct gred_sched *table,
 136                                        struct gred_sched_data *q)
 137 {
 138         table->wred_set.qavg = q->vars.qavg;
 139         table->wred_set.qidlestart = q->vars.qidlestart;
 140 }
 141
 142 static inline int gred_use_ecn(struct gred_sched *t)
 143 {
 144         return t->red_flags & TC_RED_ECN;
 145 }
 146
 147 static inline int gred_use_harddrop(struct gred_sched *t)
 148 {
 149         return t->red_flags & TC_RED_HARDDROP;
 150 }
 151
 152 static int gred_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 153                         struct sk_buff **to_free)
 154 {
 155         struct gred_sched_data *q = NULL;
 156         struct gred_sched *t = qdisc_priv(sch);
 157         unsigned long qavg = 0;
 158         u16 dp = tc_index_to_dp(skb);
 159
 160         if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
 161                 dp = t->def;
 162
 163                 q = t->tab[dp];
 164                 if (!q) {
 165                         /* Pass through packets not assigned to a DP
 166                          * if no default DP has been configured. This
 167                          * allows for DP flows to be left untouched.
 168                          */
 169                         if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <=
 170                                         sch->limit))
 171                                 return qdisc_enqueue_tail(skb, sch);
 172                         else
 173                                 goto drop;
 174                 }
 175
 176                 /* fix tc_index? --could be controversial but needed for
 177                    requeueing */
 178                 skb->tc_index = (skb->tc_index & ~GRED_VQ_MASK) | dp;
 179         }
 180
 181         /* sum up all the qaves of prios < ours to get the new qave */
 182         if (!gred_wred_mode(t) && gred_rio_mode(t)) {
 183                 int i;
 184
 185                 for (i = 0; i < t->DPs; i++) {
 186                         if (t->tab[i] && t->tab[i]->prio < q->prio &&
 187                             !red_is_idling(&t->tab[i]->vars))
 188                                 qavg += t->tab[i]->vars.qavg;
 189                 }
 190
 191         }
 192
 193         q->packetsin++;
 194         q->bytesin += qdisc_pkt_len(skb);
 195
 196         if (gred_wred_mode(t))
 197                 gred_load_wred_set(t, q);
 198
 199         q->vars.qavg = red_calc_qavg(&q->parms,
 200                                      &q->vars,
 201                                      gred_backlog(t, q, sch));
 202
 203         if (red_is_idling(&q->vars))
 204                 red_end_of_idle_period(&q->vars);
 205
 206         if (gred_wred_mode(t))
 207                 gred_store_wred_set(t, q);
 208
 209         switch (red_action(&q->parms, &q->vars, q->vars.qavg + qavg)) {
 210         case RED_DONT_MARK:
 211                 break;
 212
 213         case RED_PROB_MARK:
 214                 qdisc_qstats_overlimit(sch);
 215                 if (!gred_use_ecn(t) || !INET_ECN_set_ce(skb)) {
 216                         q->stats.prob_drop++;
 217                         goto congestion_drop;
 218                 }
 219
 220                 q->stats.prob_mark++;
 221                 break;
 222
 223         case RED_HARD_MARK:
 224                 qdisc_qstats_overlimit(sch);
 225                 if (gred_use_harddrop(t) || !gred_use_ecn(t) ||
 226                     !INET_ECN_set_ce(skb)) {
 227                         q->stats.forced_drop++;
 228                         goto congestion_drop;
 229                 }
 230                 q->stats.forced_mark++;
 231                 break;
 232         }
 233
 234         if (gred_backlog(t, q, sch) + qdisc_pkt_len(skb) <= q->limit) {
 235                 q->backlog += qdisc_pkt_len(skb);
 236                 return qdisc_enqueue_tail(skb, sch);
 237         }
 238
 239         q->stats.pdrop++;
 240 drop:
 241         return qdisc_drop(skb, sch, to_free);
 242
 243 congestion_drop:
 244         qdisc_drop(skb, sch, to_free);
 245         return NET_XMIT_CN;
 246 }
 247
 248 static struct sk_buff *gred_dequeue(struct Qdisc *sch)
 249 {
 250         struct sk_buff *skb;
 251         struct gred_sched *t = qdisc_priv(sch);
 252
 253         skb = qdisc_dequeue_head(sch);
 254
 255         if (skb) {
 256                 struct gred_sched_data *q;
 257                 u16 dp = tc_index_to_dp(skb);
 258
 259                 if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
 260                         net_warn_ratelimited("GRED: Unable to relocate VQ 0x%x after dequeue, screwing up backlog\n",
 261                                              tc_index_to_dp(skb));
 262                 } else {
 263                         q->backlog -= qdisc_pkt_len(skb);
 264
 265                         if (gred_wred_mode(t)) {
 266                                 if (!sch->qstats.backlog)
 267                                         red_start_of_idle_period(&t->wred_set);
 268                         } else {
 269                                 if (!q->backlog)
 270                                         red_start_of_idle_period(&q->vars);
 271                         }
 272                 }
 273
 274                 return skb;
 275         }
 276
 277         return NULL;
 278 }
 279
 280 static void gred_reset(struct Qdisc *sch)
 281 {
 282         int i;
 283         struct gred_sched *t = qdisc_priv(sch);
 284
 285         qdisc_reset_queue(sch);
 286
 287         for (i = 0; i < t->DPs; i++) {
 288                 struct gred_sched_data *q = t->tab[i];
 289
 290                 if (!q)
 291                         continue;
 292
 293                 red_restart(&q->vars);
 294                 q->backlog = 0;
 295         }
 296 }
 297
 298 static inline void gred_destroy_vq(struct gred_sched_data *q)
 299 {
 300         kfree(q);
 301 }
 302
 303 static inline int gred_change_table_def(struct Qdisc *sch, struct nlattr *dps)
 304 {
 305         struct gred_sched *table = qdisc_priv(sch);
 306         struct tc_gred_sopt *sopt;
 307         int i;
 308
 309         if (dps == NULL)
 310                 return -EINVAL;
 311
 312         sopt = nla_data(dps);
 313
 314         if (sopt->DPs > MAX_DPs || sopt->DPs == 0 || sopt->def_DP >= sopt->DPs)
 315                 return -EINVAL;
 316
 317         sch_tree_lock(sch);
 318         table->DPs = sopt->DPs;
 319         table->def = sopt->def_DP;
 320         table->red_flags = sopt->flags;
 321
 322         /*
 323          * Every entry point to GRED is synchronized with the above code
 324          * and the DP is checked against DPs, i.e. shadowed VQs can no
 325          * longer be found so we can unlock right here.
 326          */
 327         sch_tree_unlock(sch);
 328
 329         if (sopt->grio) {
 330                 gred_enable_rio_mode(table);
 331                 gred_disable_wred_mode(table);
 332                 if (gred_wred_mode_check(sch))
 333                         gred_enable_wred_mode(table);
 334         } else {
 335                 gred_disable_rio_mode(table);
 336                 gred_disable_wred_mode(table);
 337         }
 338
 339         for (i = table->DPs; i < MAX_DPs; i++) {
 340                 if (table->tab[i]) {
 341                         pr_warn("GRED: Warning: Destroying shadowed VQ 0x%x\n",
 342                                 i);
 343                         gred_destroy_vq(table->tab[i]);
 344                         table->tab[i] = NULL;
 345                 }
 346         }
 347
 348         return 0;
 349 }
 350
 351 static inline int gred_change_vq(struct Qdisc *sch, int dp,
 352                                  struct tc_gred_qopt *ctl, int prio,
 353                                  u8 *stab, u32 max_P,
 354                                  struct gred_sched_data **prealloc)
 355 {
 356         struct gred_sched *table = qdisc_priv(sch);
 357         struct gred_sched_data *q = table->tab[dp];
 358
 359         if (!q) {
 360                 table->tab[dp] = q = *prealloc;
 361                 *prealloc = NULL;
 362                 if (!q)
 363                         return -ENOMEM;
 364         }
 365
 366         q->DP = dp;
 367         q->prio = prio;
 368         if (ctl->limit > sch->limit)
 369                 q->limit = sch->limit;
 370         else
 371                 q->limit = ctl->limit;
 372
 373         if (q->backlog == 0)
 374                 red_end_of_idle_period(&q->vars);
 375
 376         red_set_parms(&q->parms,
 377                       ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Plog,
 378                       ctl->Scell_log, stab, max_P);
 379         red_set_vars(&q->vars);
 380         return 0;
 381 }
 382
 383 static const struct nla_policy gred_policy[TCA_GRED_MAX + 1] = {
 384         [TCA_GRED_PARMS]        = { .len = sizeof(struct tc_gred_qopt) },
 385         [TCA_GRED_STAB]         = { .len = 256 },
 386         [TCA_GRED_DPS]          = { .len = sizeof(struct tc_gred_sopt) },
 387         [TCA_GRED_MAX_P]        = { .type = NLA_U32 },
 388         [TCA_GRED_LIMIT]        = { .type = NLA_U32 },
 389 };
 390
 391 static int gred_change(struct Qdisc *sch, struct nlattr *opt)
 392 {
 393         struct gred_sched *table = qdisc_priv(sch);
 394         struct tc_gred_qopt *ctl;
 395         struct nlattr *tb[TCA_GRED_MAX + 1];
 396         int err, prio = GRED_DEF_PRIO;
 397         u8 *stab;
 398         u32 max_P;
 399         struct gred_sched_data *prealloc;
 400
 401         if (opt == NULL)
 402                 return -EINVAL;
 403
 404         err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy, NULL);
 405         if (err < 0)
 406                 return err;
 407
 408         if (tb[TCA_GRED_PARMS] == NULL && tb[TCA_GRED_STAB] == NULL) {
 409                 if (tb[TCA_GRED_LIMIT] != NULL)
 410                         sch->limit = nla_get_u32(tb[TCA_GRED_LIMIT]);
 411                 return gred_change_table_def(sch, opt);
 412         }
 413
 414         if (tb[TCA_GRED_PARMS] == NULL ||
 415             tb[TCA_GRED_STAB] == NULL ||
 416             tb[TCA_GRED_LIMIT] != NULL)
 417                 return -EINVAL;
 418
 419         max_P = tb[TCA_GRED_MAX_P] ? nla_get_u32(tb[TCA_GRED_MAX_P]) : 0;
 420
 421         err = -EINVAL;
 422         ctl = nla_data(tb[TCA_GRED_PARMS]);
 423         stab = nla_data(tb[TCA_GRED_STAB]);
 424
 425         if (ctl->DP >= table->DPs)
 426                 goto errout;
 427
 428         if (gred_rio_mode(table)) {
 429                 if (ctl->prio == 0) {
 430                         int def_prio = GRED_DEF_PRIO;
 431
 432                         if (table->tab[table->def])
 433                                 def_prio = table->tab[table->def]->prio;
 434
 435                         printk(KERN_DEBUG "GRED: DP %u does not have a prio "
 436                                "setting default to %d\n", ctl->DP, def_prio);
 437
 438                         prio = def_prio;
 439                 } else
 440                         prio = ctl->prio;
 441         }
 442
 443         prealloc = kzalloc(sizeof(*prealloc), GFP_KERNEL);
 444         sch_tree_lock(sch);
 445
 446         err = gred_change_vq(sch, ctl->DP, ctl, prio, stab, max_P, &prealloc);
 447         if (err < 0)
 448                 goto errout_locked;
 449
 450         if (gred_rio_mode(table)) {
 451                 gred_disable_wred_mode(table);
 452                 if (gred_wred_mode_check(sch))
 453                         gred_enable_wred_mode(table);
 454         }
 455
 456         err = 0;
 457
 458 errout_locked:
 459         sch_tree_unlock(sch);
 460         kfree(prealloc);
 461 errout:
 462         return err;
 463 }
 464
 465 static int gred_init(struct Qdisc *sch, struct nlattr *opt)
 466 {
 467         struct nlattr *tb[TCA_GRED_MAX + 1];
 468         int err;
 469
 470         if (opt == NULL)
 471                 return -EINVAL;
 472
 473         err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy, NULL);
 474         if (err < 0)
 475                 return err;
 476
 477         if (tb[TCA_GRED_PARMS] || tb[TCA_GRED_STAB])
 478                 return -EINVAL;
 479
 480         if (tb[TCA_GRED_LIMIT])
 481                 sch->limit = nla_get_u32(tb[TCA_GRED_LIMIT]);
 482         else
 483                 sch->limit = qdisc_dev(sch)->tx_queue_len
 484                              * psched_mtu(qdisc_dev(sch));
 485
 486         return gred_change_table_def(sch, tb[TCA_GRED_DPS]);
 487 }
 488
 489 static int gred_dump(struct Qdisc *sch, struct sk_buff *skb)
 490 {
 491         struct gred_sched *table = qdisc_priv(sch);
 492         struct nlattr *parms, *opts = NULL;
 493         int i;
 494         u32 max_p[MAX_DPs];
 495         struct tc_gred_sopt sopt = {
 496                 .DPs    = table->DPs,
 497                 .def_DP = table->def,
 498                 .grio   = gred_rio_mode(table),
 499                 .flags  = table->red_flags,
 500         };
 501
 502         opts = nla_nest_start(skb, TCA_OPTIONS);
 503         if (opts == NULL)
 504                 goto nla_put_failure;
 505         if (nla_put(skb, TCA_GRED_DPS, sizeof(sopt), &sopt))
 506                 goto nla_put_failure;
 507
 508         for (i = 0; i < MAX_DPs; i++) {
 509                 struct gred_sched_data *q = table->tab[i];
 510
 511                 max_p[i] = q ? q->parms.max_P : 0;
 512         }
 513         if (nla_put(skb, TCA_GRED_MAX_P, sizeof(max_p), max_p))
 514                 goto nla_put_failure;
 515
 516         if (nla_put_u32(skb, TCA_GRED_LIMIT, sch->limit))
 517                 goto nla_put_failure;
 518
 519         parms = nla_nest_start(skb, TCA_GRED_PARMS);
 520         if (parms == NULL)
 521                 goto nla_put_failure;
 522
 523         for (i = 0; i < MAX_DPs; i++) {
 524                 struct gred_sched_data *q = table->tab[i];
 525                 struct tc_gred_qopt opt;
 526                 unsigned long qavg;
 527
 528                 memset(&opt, 0, sizeof(opt));
 529
 530                 if (!q) {
 531                         /* hack -- fix at some point with proper message
 532                            This is how we indicate to tc that there is no VQ
 533                            at this DP */
 534
 535                         opt.DP = MAX_DPs + i;
 536                         goto append_opt;
 537                 }
 538
 539                 opt.limit       = q->limit;
 540                 opt.DP          = q->DP;
 541                 opt.backlog     = gred_backlog(table, q, sch);
 542                 opt.prio        = q->prio;
 543                 opt.qth_min     = q->parms.qth_min >> q->parms.Wlog;
 544                 opt.qth_max     = q->parms.qth_max >> q->parms.Wlog;
 545                 opt.Wlog        = q->parms.Wlog;
 546                 opt.Plog        = q->parms.Plog;
 547                 opt.Scell_log   = q->parms.Scell_log;
 548                 opt.other       = q->stats.other;
 549                 opt.early       = q->stats.prob_drop;
 550                 opt.forced      = q->stats.forced_drop;
 551                 opt.pdrop       = q->stats.pdrop;
 552                 opt.packets     = q->packetsin;
 553                 opt.bytesin     = q->bytesin;
 554
 555                 if (gred_wred_mode(table))
 556                         gred_load_wred_set(table, q);
 557
 558                 qavg = red_calc_qavg(&q->parms, &q->vars,
 559                                      q->vars.qavg >> q->parms.Wlog);
 560                 opt.qave = qavg >> q->parms.Wlog;
 561
 562 append_opt:
 563                 if (nla_append(skb, sizeof(opt), &opt) < 0)
 564                         goto nla_put_failure;
 565         }
 566
 567         nla_nest_end(skb, parms);
 568
 569         return nla_nest_end(skb, opts);
 570
 571 nla_put_failure:
 572         nla_nest_cancel(skb, opts);
 573         return -EMSGSIZE;
 574 }
 575
 576 static void gred_destroy(struct Qdisc *sch)
 577 {
 578         struct gred_sched *table = qdisc_priv(sch);
 579         int i;
 580
 581         for (i = 0; i < table->DPs; i++) {
 582                 if (table->tab[i])
 583                         gred_destroy_vq(table->tab[i]);
 584         }
 585 }
 586
 587 static struct Qdisc_ops gred_qdisc_ops __read_mostly = {
 588         .id             =       "gred",
 589         .priv_size      =       sizeof(struct gred_sched),
 590         .enqueue        =       gred_enqueue,
 591         .dequeue        =       gred_dequeue,
 592         .peek           =       qdisc_peek_head,
 593         .init           =       gred_init,
 594         .reset          =       gred_reset,
 595         .destroy        =       gred_destroy,
 596         .change         =       gred_change,
 597         .dump           =       gred_dump,
 598         .owner          =       THIS_MODULE,
 599 };
 600
 601 static int __init gred_module_init(void)
 602 {
 603         return register_qdisc(&gred_qdisc_ops);
 604 }
 605
 606 static void __exit gred_module_exit(void)
 607 {
 608         unregister_qdisc(&gred_qdisc_ops);
 609 }
 610
 611 module_init(gred_module_init)
 612 module_exit(gred_module_exit)
 613
 614 MODULE_LICENSE("GPL");