linux/net/sched/sch_gred.c
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   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
  32struct gred_sched_data;
  33struct gred_sched;
  34
  35struct 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
  48enum {
  49        GRED_WRED_MODE = 1,
  50        GRED_RIO_MODE,
  51};
  52
  53struct 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
  62static inline int gred_wred_mode(struct gred_sched *table)
  63{
  64        return test_bit(GRED_WRED_MODE, &table->flags);
  65}
  66
  67static inline void gred_enable_wred_mode(struct gred_sched *table)
  68{
  69        __set_bit(GRED_WRED_MODE, &table->flags);
  70}
  71
  72static inline void gred_disable_wred_mode(struct gred_sched *table)
  73{
  74        __clear_bit(GRED_WRED_MODE, &table->flags);
  75}
  76
  77static inline int gred_rio_mode(struct gred_sched *table)
  78{
  79        return test_bit(GRED_RIO_MODE, &table->flags);
  80}
  81
  82static inline void gred_enable_rio_mode(struct gred_sched *table)
  83{
  84        __set_bit(GRED_RIO_MODE, &table->flags);
  85}
  86
  87static inline void gred_disable_rio_mode(struct gred_sched *table)
  88{
  89        __clear_bit(GRED_RIO_MODE, &table->flags);
  90}
  91
  92static 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
 113static 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
 123static inline u16 tc_index_to_dp(struct sk_buff *skb)
 124{
 125        return skb->tc_index & GRED_VQ_MASK;
 126}
 127
 128static 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
 135static 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
 142static inline int gred_use_ecn(struct gred_sched *t)
 143{
 144        return t->red_flags & TC_RED_ECN;
 145}
 146
 147static inline int gred_use_harddrop(struct gred_sched *t)
 148{
 149        return t->red_flags & TC_RED_HARDDROP;
 150}
 151
 152static int gred_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 153{
 154        struct gred_sched_data *q = NULL;
 155        struct gred_sched *t = qdisc_priv(sch);
 156        unsigned long qavg = 0;
 157        u16 dp = tc_index_to_dp(skb);
 158
 159        if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
 160                dp = t->def;
 161
 162                q = t->tab[dp];
 163                if (!q) {
 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) < qdisc_dev(sch)->tx_queue_len)
 169                                return qdisc_enqueue_tail(skb, sch);
 170                        else
 171                                goto drop;
 172                }
 173
 174                /* fix tc_index? --could be controversial 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 < 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]->vars))
 186                                qavg += t->tab[i]->vars.qavg;
 187                }
 188
 189        }
 190
 191        q->packetsin++;
 192        q->bytesin += qdisc_pkt_len(skb);
 193
 194        if (gred_wred_mode(t))
 195                gred_load_wred_set(t, q);
 196
 197        q->vars.qavg = red_calc_qavg(&q->parms,
 198                                     &q->vars,
 199                                     gred_backlog(t, q, sch));
 200
 201        if (red_is_idling(&q->vars))
 202                red_end_of_idle_period(&q->vars);
 203
 204        if (gred_wred_mode(t))
 205                gred_store_wred_set(t, q);
 206
 207        switch (red_action(&q->parms, &q->vars, q->vars.qavg + qavg)) {
 208        case RED_DONT_MARK:
 209                break;
 210
 211        case RED_PROB_MARK:
 212                sch->qstats.overlimits++;
 213                if (!gred_use_ecn(t) || !INET_ECN_set_ce(skb)) {
 214                        q->stats.prob_drop++;
 215                        goto congestion_drop;
 216                }
 217
 218                q->stats.prob_mark++;
 219                break;
 220
 221        case RED_HARD_MARK:
 222                sch->qstats.overlimits++;
 223                if (gred_use_harddrop(t) || !gred_use_ecn(t) ||
 224                    !INET_ECN_set_ce(skb)) {
 225                        q->stats.forced_drop++;
 226                        goto congestion_drop;
 227                }
 228                q->stats.forced_mark++;
 229                break;
 230        }
 231
 232        if (q->backlog + qdisc_pkt_len(skb) <= q->limit) {
 233                q->backlog += qdisc_pkt_len(skb);
 234                return qdisc_enqueue_tail(skb, sch);
 235        }
 236
 237        q->stats.pdrop++;
 238drop:
 239        return qdisc_drop(skb, sch);
 240
 241congestion_drop:
 242        qdisc_drop(skb, sch);
 243        return NET_XMIT_CN;
 244}
 245
 246static struct sk_buff *gred_dequeue(struct Qdisc *sch)
 247{
 248        struct sk_buff *skb;
 249        struct gred_sched *t = qdisc_priv(sch);
 250
 251        skb = qdisc_dequeue_head(sch);
 252
 253        if (skb) {
 254                struct gred_sched_data *q;
 255                u16 dp = tc_index_to_dp(skb);
 256
 257                if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
 258                        net_warn_ratelimited("GRED: Unable to relocate VQ 0x%x after dequeue, screwing up backlog\n",
 259                                             tc_index_to_dp(skb));
 260                } else {
 261                        q->backlog -= qdisc_pkt_len(skb);
 262
 263                        if (gred_wred_mode(t)) {
 264                                if (!sch->qstats.backlog)
 265                                        red_start_of_idle_period(&t->wred_set);
 266                        } else {
 267                                if (!q->backlog)
 268                                        red_start_of_idle_period(&q->vars);
 269                        }
 270                }
 271
 272                return skb;
 273        }
 274
 275        return NULL;
 276}
 277
 278static unsigned int gred_drop(struct Qdisc *sch)
 279{
 280        struct sk_buff *skb;
 281        struct gred_sched *t = qdisc_priv(sch);
 282
 283        skb = qdisc_dequeue_tail(sch);
 284        if (skb) {
 285                unsigned int len = qdisc_pkt_len(skb);
 286                struct gred_sched_data *q;
 287                u16 dp = tc_index_to_dp(skb);
 288
 289                if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
 290                        net_warn_ratelimited("GRED: Unable to relocate VQ 0x%x while dropping, screwing up backlog\n",
 291                                             tc_index_to_dp(skb));
 292                } else {
 293                        q->backlog -= len;
 294                        q->stats.other++;
 295
 296                        if (gred_wred_mode(t)) {
 297                                if (!sch->qstats.backlog)
 298                                        red_start_of_idle_period(&t->wred_set);
 299                        } else {
 300                                if (!q->backlog)
 301                                        red_start_of_idle_period(&q->vars);
 302                        }
 303                }
 304
 305                qdisc_drop(skb, sch);
 306                return len;
 307        }
 308
 309        return 0;
 310}
 311
 312static void gred_reset(struct Qdisc *sch)
 313{
 314        int i;
 315        struct gred_sched *t = qdisc_priv(sch);
 316
 317        qdisc_reset_queue(sch);
 318
 319        for (i = 0; i < t->DPs; i++) {
 320                struct gred_sched_data *q = t->tab[i];
 321
 322                if (!q)
 323                        continue;
 324
 325                red_restart(&q->vars);
 326                q->backlog = 0;
 327        }
 328}
 329
 330static inline void gred_destroy_vq(struct gred_sched_data *q)
 331{
 332        kfree(q);
 333}
 334
 335static inline int gred_change_table_def(struct Qdisc *sch, struct nlattr *dps)
 336{
 337        struct gred_sched *table = qdisc_priv(sch);
 338        struct tc_gred_sopt *sopt;
 339        int i;
 340
 341        if (dps == NULL)
 342                return -EINVAL;
 343
 344        sopt = nla_data(dps);
 345
 346        if (sopt->DPs > MAX_DPs || sopt->DPs == 0 || sopt->def_DP >= sopt->DPs)
 347                return -EINVAL;
 348
 349        sch_tree_lock(sch);
 350        table->DPs = sopt->DPs;
 351        table->def = sopt->def_DP;
 352        table->red_flags = sopt->flags;
 353
 354        /*
 355         * Every entry point to GRED is synchronized with the above code
 356         * and the DP is checked against DPs, i.e. shadowed VQs can no
 357         * longer be found so we can unlock right here.
 358         */
 359        sch_tree_unlock(sch);
 360
 361        if (sopt->grio) {
 362                gred_enable_rio_mode(table);
 363                gred_disable_wred_mode(table);
 364                if (gred_wred_mode_check(sch))
 365                        gred_enable_wred_mode(table);
 366        } else {
 367                gred_disable_rio_mode(table);
 368                gred_disable_wred_mode(table);
 369        }
 370
 371        for (i = table->DPs; i < MAX_DPs; i++) {
 372                if (table->tab[i]) {
 373                        pr_warning("GRED: Warning: Destroying "
 374                                   "shadowed VQ 0x%x\n", i);
 375                        gred_destroy_vq(table->tab[i]);
 376                        table->tab[i] = NULL;
 377                }
 378        }
 379
 380        return 0;
 381}
 382
 383static inline int gred_change_vq(struct Qdisc *sch, int dp,
 384                                 struct tc_gred_qopt *ctl, int prio,
 385                                 u8 *stab, u32 max_P,
 386                                 struct gred_sched_data **prealloc)
 387{
 388        struct gred_sched *table = qdisc_priv(sch);
 389        struct gred_sched_data *q = table->tab[dp];
 390
 391        if (!q) {
 392                table->tab[dp] = q = *prealloc;
 393                *prealloc = NULL;
 394                if (!q)
 395                        return -ENOMEM;
 396        }
 397
 398        q->DP = dp;
 399        q->prio = prio;
 400        q->limit = ctl->limit;
 401
 402        if (q->backlog == 0)
 403                red_end_of_idle_period(&q->vars);
 404
 405        red_set_parms(&q->parms,
 406                      ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Plog,
 407                      ctl->Scell_log, stab, max_P);
 408        red_set_vars(&q->vars);
 409        return 0;
 410}
 411
 412static const struct nla_policy gred_policy[TCA_GRED_MAX + 1] = {
 413        [TCA_GRED_PARMS]        = { .len = sizeof(struct tc_gred_qopt) },
 414        [TCA_GRED_STAB]         = { .len = 256 },
 415        [TCA_GRED_DPS]          = { .len = sizeof(struct tc_gred_sopt) },
 416        [TCA_GRED_MAX_P]        = { .type = NLA_U32 },
 417};
 418
 419static int gred_change(struct Qdisc *sch, struct nlattr *opt)
 420{
 421        struct gred_sched *table = qdisc_priv(sch);
 422        struct tc_gred_qopt *ctl;
 423        struct nlattr *tb[TCA_GRED_MAX + 1];
 424        int err, prio = GRED_DEF_PRIO;
 425        u8 *stab;
 426        u32 max_P;
 427        struct gred_sched_data *prealloc;
 428
 429        if (opt == NULL)
 430                return -EINVAL;
 431
 432        err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy);
 433        if (err < 0)
 434                return err;
 435
 436        if (tb[TCA_GRED_PARMS] == NULL && tb[TCA_GRED_STAB] == NULL)
 437                return gred_change_table_def(sch, opt);
 438
 439        if (tb[TCA_GRED_PARMS] == NULL ||
 440            tb[TCA_GRED_STAB] == NULL)
 441                return -EINVAL;
 442
 443        max_P = tb[TCA_GRED_MAX_P] ? nla_get_u32(tb[TCA_GRED_MAX_P]) : 0;
 444
 445        err = -EINVAL;
 446        ctl = nla_data(tb[TCA_GRED_PARMS]);
 447        stab = nla_data(tb[TCA_GRED_STAB]);
 448
 449        if (ctl->DP >= table->DPs)
 450                goto errout;
 451
 452        if (gred_rio_mode(table)) {
 453                if (ctl->prio == 0) {
 454                        int def_prio = GRED_DEF_PRIO;
 455
 456                        if (table->tab[table->def])
 457                                def_prio = table->tab[table->def]->prio;
 458
 459                        printk(KERN_DEBUG "GRED: DP %u does not have a prio "
 460                               "setting default to %d\n", ctl->DP, def_prio);
 461
 462                        prio = def_prio;
 463                } else
 464                        prio = ctl->prio;
 465        }
 466
 467        prealloc = kzalloc(sizeof(*prealloc), GFP_KERNEL);
 468        sch_tree_lock(sch);
 469
 470        err = gred_change_vq(sch, ctl->DP, ctl, prio, stab, max_P, &prealloc);
 471        if (err < 0)
 472                goto errout_locked;
 473
 474        if (gred_rio_mode(table)) {
 475                gred_disable_wred_mode(table);
 476                if (gred_wred_mode_check(sch))
 477                        gred_enable_wred_mode(table);
 478        }
 479
 480        err = 0;
 481
 482errout_locked:
 483        sch_tree_unlock(sch);
 484        kfree(prealloc);
 485errout:
 486        return err;
 487}
 488
 489static int gred_init(struct Qdisc *sch, struct nlattr *opt)
 490{
 491        struct nlattr *tb[TCA_GRED_MAX + 1];
 492        int err;
 493
 494        if (opt == NULL)
 495                return -EINVAL;
 496
 497        err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy);
 498        if (err < 0)
 499                return err;
 500
 501        if (tb[TCA_GRED_PARMS] || tb[TCA_GRED_STAB])
 502                return -EINVAL;
 503
 504        return gred_change_table_def(sch, tb[TCA_GRED_DPS]);
 505}
 506
 507static int gred_dump(struct Qdisc *sch, struct sk_buff *skb)
 508{
 509        struct gred_sched *table = qdisc_priv(sch);
 510        struct nlattr *parms, *opts = NULL;
 511        int i;
 512        u32 max_p[MAX_DPs];
 513        struct tc_gred_sopt sopt = {
 514                .DPs    = table->DPs,
 515                .def_DP = table->def,
 516                .grio   = gred_rio_mode(table),
 517                .flags  = table->red_flags,
 518        };
 519
 520        opts = nla_nest_start(skb, TCA_OPTIONS);
 521        if (opts == NULL)
 522                goto nla_put_failure;
 523        if (nla_put(skb, TCA_GRED_DPS, sizeof(sopt), &sopt))
 524                goto nla_put_failure;
 525
 526        for (i = 0; i < MAX_DPs; i++) {
 527                struct gred_sched_data *q = table->tab[i];
 528
 529                max_p[i] = q ? q->parms.max_P : 0;
 530        }
 531        if (nla_put(skb, TCA_GRED_MAX_P, sizeof(max_p), max_p))
 532                goto nla_put_failure;
 533
 534        parms = nla_nest_start(skb, TCA_GRED_PARMS);
 535        if (parms == NULL)
 536                goto nla_put_failure;
 537
 538        for (i = 0; i < MAX_DPs; i++) {
 539                struct gred_sched_data *q = table->tab[i];
 540                struct tc_gred_qopt opt;
 541                unsigned long qavg;
 542
 543                memset(&opt, 0, sizeof(opt));
 544
 545                if (!q) {
 546                        /* hack -- fix at some point with proper message
 547                           This is how we indicate to tc that there is no VQ
 548                           at this DP */
 549
 550                        opt.DP = MAX_DPs + i;
 551                        goto append_opt;
 552                }
 553
 554                opt.limit       = q->limit;
 555                opt.DP          = q->DP;
 556                opt.backlog     = q->backlog;
 557                opt.prio        = q->prio;
 558                opt.qth_min     = q->parms.qth_min >> q->parms.Wlog;
 559                opt.qth_max     = q->parms.qth_max >> q->parms.Wlog;
 560                opt.Wlog        = q->parms.Wlog;
 561                opt.Plog        = q->parms.Plog;
 562                opt.Scell_log   = q->parms.Scell_log;
 563                opt.other       = q->stats.other;
 564                opt.early       = q->stats.prob_drop;
 565                opt.forced      = q->stats.forced_drop;
 566                opt.pdrop       = q->stats.pdrop;
 567                opt.packets     = q->packetsin;
 568                opt.bytesin     = q->bytesin;
 569
 570                if (gred_wred_mode(table))
 571                        gred_load_wred_set(table, q);
 572
 573                qavg = red_calc_qavg(&q->parms, &q->vars,
 574                                     q->vars.qavg >> q->parms.Wlog);
 575                opt.qave = qavg >> q->parms.Wlog;
 576
 577append_opt:
 578                if (nla_append(skb, sizeof(opt), &opt) < 0)
 579                        goto nla_put_failure;
 580        }
 581
 582        nla_nest_end(skb, parms);
 583
 584        return nla_nest_end(skb, opts);
 585
 586nla_put_failure:
 587        nla_nest_cancel(skb, opts);
 588        return -EMSGSIZE;
 589}
 590
 591static void gred_destroy(struct Qdisc *sch)
 592{
 593        struct gred_sched *table = qdisc_priv(sch);
 594        int i;
 595
 596        for (i = 0; i < table->DPs; i++) {
 597                if (table->tab[i])
 598                        gred_destroy_vq(table->tab[i]);
 599        }
 600}
 601
 602static struct Qdisc_ops gred_qdisc_ops __read_mostly = {
 603        .id             =       "gred",
 604        .priv_size      =       sizeof(struct gred_sched),
 605        .enqueue        =       gred_enqueue,
 606        .dequeue        =       gred_dequeue,
 607        .peek           =       qdisc_peek_head,
 608        .drop           =       gred_drop,
 609        .init           =       gred_init,
 610        .reset          =       gred_reset,
 611        .destroy        =       gred_destroy,
 612        .change         =       gred_change,
 613        .dump           =       gred_dump,
 614        .owner          =       THIS_MODULE,
 615};
 616
 617static int __init gred_module_init(void)
 618{
 619        return register_qdisc(&gred_qdisc_ops);
 620}
 621
 622static void __exit gred_module_exit(void)
 623{
 624        unregister_qdisc(&gred_qdisc_ops);
 625}
 626
 627module_init(gred_module_init)
 628module_exit(gred_module_exit)
 629
 630MODULE_LICENSE("GPL");
 631
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