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