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