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 }
 140
 141 static inline int gred_use_ecn(struct gred_sched *t)
 142 {
 143         return t->red_flags & TC_RED_ECN;
 144 }
 145
 146 static inline int gred_use_harddrop(struct gred_sched *t)
 147 {
 148         return t->red_flags & TC_RED_HARDDROP;
 149 }
 150
 151 static int gred_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 152 {
 153         struct gred_sched_data *q = NULL;
 154         struct gred_sched *t = qdisc_priv(sch);
 155         unsigned long qavg = 0;
 156         u16 dp = tc_index_to_dp(skb);
 157
 158         if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
 159                 dp = t->def;
 160
 161                 q = t->tab[dp];
 162                 if (!q) {
 163                         /* Pass through packets not assigned to a DP
 164                          * if no default DP has been configured. This
 165                          * allows for DP flows to be left untouched.
 166                          */
 167                         if (skb_queue_len(&sch->q) < qdisc_dev(sch)->tx_queue_len)
 168                                 return qdisc_enqueue_tail(skb, sch);
 169                         else
 170                                 goto drop;
 171                 }
 172
 173                 /* fix tc_index? --could be controversial but needed for
 174                    requeueing */
 175                 skb->tc_index = (skb->tc_index & ~GRED_VQ_MASK) | dp;
 176         }
 177
 178         /* sum up all the qaves of prios < ours to get the new qave */
 179         if (!gred_wred_mode(t) && gred_rio_mode(t)) {
 180                 int i;
 181
 182                 for (i = 0; i < t->DPs; i++) {
 183                         if (t->tab[i] && t->tab[i]->prio < q->prio &&
 184                             !red_is_idling(&t->tab[i]->vars))
 185                                 qavg += t->tab[i]->vars.qavg;
 186                 }
 187
 188         }
 189
 190         q->packetsin++;
 191         q->bytesin += qdisc_pkt_len(skb);
 192
 193         if (gred_wred_mode(t))
 194                 gred_load_wred_set(t, q);
 195
 196         q->vars.qavg = red_calc_qavg(&q->parms,
 197                                      &q->vars,
 198                                      gred_backlog(t, q, sch));
 199
 200         if (red_is_idling(&q->vars))
 201                 red_end_of_idle_period(&q->vars);
 202
 203         if (gred_wred_mode(t))
 204                 gred_store_wred_set(t, q);
 205
 206         switch (red_action(&q->parms, &q->vars, q->vars.qavg + qavg)) {
 207         case RED_DONT_MARK:
 208                 break;
 209
 210         case RED_PROB_MARK:
 211                 sch->qstats.overlimits++;
 212                 if (!gred_use_ecn(t) || !INET_ECN_set_ce(skb)) {
 213                         q->stats.prob_drop++;
 214                         goto congestion_drop;
 215                 }
 216
 217                 q->stats.prob_mark++;
 218                 break;
 219
 220         case RED_HARD_MARK:
 221                 sch->qstats.overlimits++;
 222                 if (gred_use_harddrop(t) || !gred_use_ecn(t) ||
 223                     !INET_ECN_set_ce(skb)) {
 224                         q->stats.forced_drop++;
 225                         goto congestion_drop;
 226                 }
 227                 q->stats.forced_mark++;
 228                 break;
 229         }
 230
 231         if (q->backlog + qdisc_pkt_len(skb) <= q->limit) {
 232                 q->backlog += qdisc_pkt_len(skb);
 233                 return qdisc_enqueue_tail(skb, sch);
 234         }
 235
 236         q->stats.pdrop++;
 237 drop:
 238         return qdisc_drop(skb, sch);
 239
 240 congestion_drop:
 241         qdisc_drop(skb, sch);
 242         return NET_XMIT_CN;
 243 }
 244
 245 static struct sk_buff *gred_dequeue(struct Qdisc *sch)
 246 {
 247         struct sk_buff *skb;
 248         struct gred_sched *t = qdisc_priv(sch);
 249
 250         skb = qdisc_dequeue_head(sch);
 251
 252         if (skb) {
 253                 struct gred_sched_data *q;
 254                 u16 dp = tc_index_to_dp(skb);
 255
 256                 if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
 257                         net_warn_ratelimited("GRED: Unable to relocate VQ 0x%x after dequeue, screwing up backlog\n",
 258                                              tc_index_to_dp(skb));
 259                 } else {
 260                         q->backlog -= qdisc_pkt_len(skb);
 261
 262                         if (!q->backlog && !gred_wred_mode(t))
 263                                 red_start_of_idle_period(&q->vars);
 264                 }
 265
 266                 return skb;
 267         }
 268
 269         if (gred_wred_mode(t) && !red_is_idling(&t->wred_set))
 270                 red_start_of_idle_period(&t->wred_set);
 271
 272         return NULL;
 273 }
 274
 275 static unsigned int gred_drop(struct Qdisc *sch)
 276 {
 277         struct sk_buff *skb;
 278         struct gred_sched *t = qdisc_priv(sch);
 279
 280         skb = qdisc_dequeue_tail(sch);
 281         if (skb) {
 282                 unsigned int len = qdisc_pkt_len(skb);
 283                 struct gred_sched_data *q;
 284                 u16 dp = tc_index_to_dp(skb);
 285
 286                 if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
 287                         net_warn_ratelimited("GRED: Unable to relocate VQ 0x%x while dropping, screwing up backlog\n",
 288                                              tc_index_to_dp(skb));
 289                 } else {
 290                         q->backlog -= len;
 291                         q->stats.other++;
 292
 293                         if (!q->backlog && !gred_wred_mode(t))
 294                                 red_start_of_idle_period(&q->vars);
 295                 }
 296
 297                 qdisc_drop(skb, sch);
 298                 return len;
 299         }
 300
 301         if (gred_wred_mode(t) && !red_is_idling(&t->wred_set))
 302                 red_start_of_idle_period(&t->wred_set);
 303
 304         return 0;
 305
 306 }
 307
 308 static void gred_reset(struct Qdisc *sch)
 309 {
 310         int i;
 311         struct gred_sched *t = qdisc_priv(sch);
 312
 313         qdisc_reset_queue(sch);
 314
 315         for (i = 0; i < t->DPs; i++) {
 316                 struct gred_sched_data *q = t->tab[i];
 317
 318                 if (!q)
 319                         continue;
 320
 321                 red_restart(&q->vars);
 322                 q->backlog = 0;
 323         }
 324 }
 325
 326 static inline void gred_destroy_vq(struct gred_sched_data *q)
 327 {
 328         kfree(q);
 329 }
 330
 331 static inline int gred_change_table_def(struct Qdisc *sch, struct nlattr *dps)
 332 {
 333         struct gred_sched *table = qdisc_priv(sch);
 334         struct tc_gred_sopt *sopt;
 335         int i;
 336
 337         if (dps == NULL)
 338                 return -EINVAL;
 339
 340         sopt = nla_data(dps);
 341
 342         if (sopt->DPs > MAX_DPs || sopt->DPs == 0 || sopt->def_DP >= sopt->DPs)
 343                 return -EINVAL;
 344
 345         sch_tree_lock(sch);
 346         table->DPs = sopt->DPs;
 347         table->def = sopt->def_DP;
 348         table->red_flags = sopt->flags;
 349
 350         /*
 351          * Every entry point to GRED is synchronized with the above code
 352          * and the DP is checked against DPs, i.e. shadowed VQs can no
 353          * longer be found so we can unlock right here.
 354          */
 355         sch_tree_unlock(sch);
 356
 357         if (sopt->grio) {
 358                 gred_enable_rio_mode(table);
 359                 gred_disable_wred_mode(table);
 360                 if (gred_wred_mode_check(sch))
 361                         gred_enable_wred_mode(table);
 362         } else {
 363                 gred_disable_rio_mode(table);
 364                 gred_disable_wred_mode(table);
 365         }
 366
 367         for (i = table->DPs; i < MAX_DPs; i++) {
 368                 if (table->tab[i]) {
 369                         pr_warning("GRED: Warning: Destroying "
 370                                    "shadowed VQ 0x%x\n", i);
 371                         gred_destroy_vq(table->tab[i]);
 372                         table->tab[i] = NULL;
 373                 }
 374         }
 375
 376         return 0;
 377 }
 378
 379 static inline int gred_change_vq(struct Qdisc *sch, int dp,
 380                                  struct tc_gred_qopt *ctl, int prio,
 381                                  u8 *stab, u32 max_P,
 382                                  struct gred_sched_data **prealloc)
 383 {
 384         struct gred_sched *table = qdisc_priv(sch);
 385         struct gred_sched_data *q = table->tab[dp];
 386
 387         if (!q) {
 388                 table->tab[dp] = q = *prealloc;
 389                 *prealloc = NULL;
 390                 if (!q)
 391                         return -ENOMEM;
 392         }
 393
 394         q->DP = dp;
 395         q->prio = prio;
 396         q->limit = ctl->limit;
 397
 398         if (q->backlog == 0)
 399                 red_end_of_idle_period(&q->vars);
 400
 401         red_set_parms(&q->parms,
 402                       ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Plog,
 403                       ctl->Scell_log, stab, max_P);
 404         red_set_vars(&q->vars);
 405         return 0;
 406 }
 407
 408 static const struct nla_policy gred_policy[TCA_GRED_MAX + 1] = {
 409         [TCA_GRED_PARMS]        = { .len = sizeof(struct tc_gred_qopt) },
 410         [TCA_GRED_STAB]         = { .len = 256 },
 411         [TCA_GRED_DPS]          = { .len = sizeof(struct tc_gred_sopt) },
 412         [TCA_GRED_MAX_P]        = { .type = NLA_U32 },
 413 };
 414
 415 static int gred_change(struct Qdisc *sch, struct nlattr *opt)
 416 {
 417         struct gred_sched *table = qdisc_priv(sch);
 418         struct tc_gred_qopt *ctl;
 419         struct nlattr *tb[TCA_GRED_MAX + 1];
 420         int err, prio = GRED_DEF_PRIO;
 421         u8 *stab;
 422         u32 max_P;
 423         struct gred_sched_data *prealloc;
 424
 425         if (opt == NULL)
 426                 return -EINVAL;
 427
 428         err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy);
 429         if (err < 0)
 430                 return err;
 431
 432         if (tb[TCA_GRED_PARMS] == NULL && tb[TCA_GRED_STAB] == NULL)
 433                 return gred_change_table_def(sch, opt);
 434
 435         if (tb[TCA_GRED_PARMS] == NULL ||
 436             tb[TCA_GRED_STAB] == NULL)
 437                 return -EINVAL;
 438
 439         max_P = tb[TCA_GRED_MAX_P] ? nla_get_u32(tb[TCA_GRED_MAX_P]) : 0;
 440
 441         err = -EINVAL;
 442         ctl = nla_data(tb[TCA_GRED_PARMS]);
 443         stab = nla_data(tb[TCA_GRED_STAB]);
 444
 445         if (ctl->DP >= table->DPs)
 446                 goto errout;
 447
 448         if (gred_rio_mode(table)) {
 449                 if (ctl->prio == 0) {
 450                         int def_prio = GRED_DEF_PRIO;
 451
 452                         if (table->tab[table->def])
 453                                 def_prio = table->tab[table->def]->prio;
 454
 455                         printk(KERN_DEBUG "GRED: DP %u does not have a prio "
 456                                "setting default to %d\n", ctl->DP, def_prio);
 457
 458                         prio = def_prio;
 459                 } else
 460                         prio = ctl->prio;
 461         }
 462
 463         prealloc = kzalloc(sizeof(*prealloc), GFP_KERNEL);
 464         sch_tree_lock(sch);
 465
 466         err = gred_change_vq(sch, ctl->DP, ctl, prio, stab, max_P, &prealloc);
 467         if (err < 0)
 468                 goto errout_locked;
 469
 470         if (gred_rio_mode(table)) {
 471                 gred_disable_wred_mode(table);
 472                 if (gred_wred_mode_check(sch))
 473                         gred_enable_wred_mode(table);
 474         }
 475
 476         err = 0;
 477
 478 errout_locked:
 479         sch_tree_unlock(sch);
 480         kfree(prealloc);
 481 errout:
 482         return err;
 483 }
 484
 485 static int gred_init(struct Qdisc *sch, struct nlattr *opt)
 486 {
 487         struct nlattr *tb[TCA_GRED_MAX + 1];
 488         int err;
 489
 490         if (opt == NULL)
 491                 return -EINVAL;
 492
 493         err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy);
 494         if (err < 0)
 495                 return err;
 496
 497         if (tb[TCA_GRED_PARMS] || tb[TCA_GRED_STAB])
 498                 return -EINVAL;
 499
 500         return gred_change_table_def(sch, tb[TCA_GRED_DPS]);
 501 }
 502
 503 static int gred_dump(struct Qdisc *sch, struct sk_buff *skb)
 504 {
 505         struct gred_sched *table = qdisc_priv(sch);
 506         struct nlattr *parms, *opts = NULL;
 507         int i;
 508         u32 max_p[MAX_DPs];
 509         struct tc_gred_sopt sopt = {
 510                 .DPs    = table->DPs,
 511                 .def_DP = table->def,
 512                 .grio   = gred_rio_mode(table),
 513                 .flags  = table->red_flags,
 514         };
 515
 516         opts = nla_nest_start(skb, TCA_OPTIONS);
 517         if (opts == NULL)
 518                 goto nla_put_failure;
 519         if (nla_put(skb, TCA_GRED_DPS, sizeof(sopt), &sopt))
 520                 goto nla_put_failure;
 521
 522         for (i = 0; i < MAX_DPs; i++) {
 523                 struct gred_sched_data *q = table->tab[i];
 524
 525                 max_p[i] = q ? q->parms.max_P : 0;
 526         }
 527         if (nla_put(skb, TCA_GRED_MAX_P, sizeof(max_p), max_p))
 528                 goto nla_put_failure;
 529
 530         parms = nla_nest_start(skb, TCA_GRED_PARMS);
 531         if (parms == NULL)
 532                 goto nla_put_failure;
 533
 534         for (i = 0; i < MAX_DPs; i++) {
 535                 struct gred_sched_data *q = table->tab[i];
 536                 struct tc_gred_qopt opt;
 537
 538                 memset(&opt, 0, sizeof(opt));
 539
 540                 if (!q) {
 541                         /* hack -- fix at some point with proper message
 542                            This is how we indicate to tc that there is no VQ
 543                            at this DP */
 544
 545                         opt.DP = MAX_DPs + i;
 546                         goto append_opt;
 547                 }
 548
 549                 opt.limit       = q->limit;
 550                 opt.DP          = q->DP;
 551                 opt.backlog     = q->backlog;
 552                 opt.prio        = q->prio;
 553                 opt.qth_min     = q->parms.qth_min >> q->parms.Wlog;
 554                 opt.qth_max     = q->parms.qth_max >> q->parms.Wlog;
 555                 opt.Wlog        = q->parms.Wlog;
 556                 opt.Plog        = q->parms.Plog;
 557                 opt.Scell_log   = q->parms.Scell_log;
 558                 opt.other       = q->stats.other;
 559                 opt.early       = q->stats.prob_drop;
 560                 opt.forced      = q->stats.forced_drop;
 561                 opt.pdrop       = q->stats.pdrop;
 562                 opt.packets     = q->packetsin;
 563                 opt.bytesin     = q->bytesin;
 564
 565                 if (gred_wred_mode(table))
 566                         gred_load_wred_set(table, q);
 567
 568                 opt.qave = red_calc_qavg(&q->parms, &q->vars, q->vars.qavg);
 569
 570 append_opt:
 571                 if (nla_append(skb, sizeof(opt), &opt) < 0)
 572                         goto nla_put_failure;
 573         }
 574
 575         nla_nest_end(skb, parms);
 576
 577         return nla_nest_end(skb, opts);
 578
 579 nla_put_failure:
 580         nla_nest_cancel(skb, opts);
 581         return -EMSGSIZE;
 582 }
 583
 584 static void gred_destroy(struct Qdisc *sch)
 585 {
 586         struct gred_sched *table = qdisc_priv(sch);
 587         int i;
 588
 589         for (i = 0; i < table->DPs; i++) {
 590                 if (table->tab[i])
 591                         gred_destroy_vq(table->tab[i]);
 592         }
 593 }
 594
 595 static struct Qdisc_ops gred_qdisc_ops __read_mostly = {
 596         .id             =       "gred",
 597         .priv_size      =       sizeof(struct gred_sched),
 598         .enqueue        =       gred_enqueue,
 599         .dequeue        =       gred_dequeue,
 600         .peek           =       qdisc_peek_head,
 601         .drop           =       gred_drop,
 602         .init           =       gred_init,
 603         .reset          =       gred_reset,
 604         .destroy        =       gred_destroy,
 605         .change         =       gred_change,
 606         .dump           =       gred_dump,
 607         .owner          =       THIS_MODULE,
 608 };
 609
 610 static int __init gred_module_init(void)
 611 {
 612         return register_qdisc(&gred_qdisc_ops);
 613 }
 614
 615 static void __exit gred_module_exit(void)
 616 {
 617         unregister_qdisc(&gred_qdisc_ops);
 618 }
 619
 620 module_init(gred_module_init)
 621 module_exit(gred_module_exit)
 622
 623 MODULE_LICENSE("GPL");