net/sched/sch_prio.c

   1 /*
   2  * net/sched/sch_prio.c Simple 3-band priority "scheduler".
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  * Fixes:       19990609: J Hadi Salim <hadi@nortelnetworks.com>:
  11  *              Init --  EINVAL when opt undefined
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/string.h>
  18 #include <linux/errno.h>
  19 #include <linux/skbuff.h>
  20 #include <net/netlink.h>
  21 #include <net/pkt_sched.h>
  22
  23
  24 struct prio_sched_data
  25 {
  26         int bands;
  27         int curband; /* for round-robin */
  28         struct tcf_proto *filter_list;
  29         u8  prio2band[TC_PRIO_MAX+1];
  30         struct Qdisc *queues[TCQ_PRIO_BANDS];
  31         int mq;
  32 };
  33
  34
  35 static struct Qdisc *
  36 prio_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
  37 {
  38         struct prio_sched_data *q = qdisc_priv(sch);
  39         u32 band = skb->priority;
  40         struct tcf_result res;
  41         int err;
  42
  43         *qerr = NET_XMIT_BYPASS;
  44         if (TC_H_MAJ(skb->priority) != sch->handle) {
  45                 err = tc_classify(skb, q->filter_list, &res);
  46 #ifdef CONFIG_NET_CLS_ACT
  47                 switch (err) {
  48                 case TC_ACT_STOLEN:
  49                 case TC_ACT_QUEUED:
  50                         *qerr = NET_XMIT_SUCCESS;
  51                 case TC_ACT_SHOT:
  52                         return NULL;
  53                 }
  54 #endif
  55                 if (!q->filter_list || err < 0) {
  56                         if (TC_H_MAJ(band))
  57                                 band = 0;
  58                         band = q->prio2band[band&TC_PRIO_MAX];
  59                         goto out;
  60                 }
  61                 band = res.classid;
  62         }
  63         band = TC_H_MIN(band) - 1;
  64         if (band >= q->bands)
  65                 band = q->prio2band[0];
  66 out:
  67         if (q->mq)
  68                 skb_set_queue_mapping(skb, band);
  69         return q->queues[band];
  70 }
  71
  72 static int
  73 prio_enqueue(struct sk_buff *skb, struct Qdisc *sch)
  74 {
  75         struct Qdisc *qdisc;
  76         int ret;
  77
  78         qdisc = prio_classify(skb, sch, &ret);
  79 #ifdef CONFIG_NET_CLS_ACT
  80         if (qdisc == NULL) {
  81
  82                 if (ret == NET_XMIT_BYPASS)
  83                         sch->qstats.drops++;
  84                 kfree_skb(skb);
  85                 return ret;
  86         }
  87 #endif
  88
  89         if ((ret = qdisc->enqueue(skb, qdisc)) == NET_XMIT_SUCCESS) {
  90                 sch->bstats.bytes += skb->len;
  91                 sch->bstats.packets++;
  92                 sch->q.qlen++;
  93                 return NET_XMIT_SUCCESS;
  94         }
  95         sch->qstats.drops++;
  96         return ret;
  97 }
  98
  99
 100 static int
 101 prio_requeue(struct sk_buff *skb, struct Qdisc* sch)
 102 {
 103         struct Qdisc *qdisc;
 104         int ret;
 105
 106         qdisc = prio_classify(skb, sch, &ret);
 107 #ifdef CONFIG_NET_CLS_ACT
 108         if (qdisc == NULL) {
 109                 if (ret == NET_XMIT_BYPASS)
 110                         sch->qstats.drops++;
 111                 kfree_skb(skb);
 112                 return ret;
 113         }
 114 #endif
 115
 116         if ((ret = qdisc->ops->requeue(skb, qdisc)) == NET_XMIT_SUCCESS) {
 117                 sch->q.qlen++;
 118                 sch->qstats.requeues++;
 119                 return 0;
 120         }
 121         sch->qstats.drops++;
 122         return NET_XMIT_DROP;
 123 }
 124
 125
 126 static struct sk_buff *
 127 prio_dequeue(struct Qdisc* sch)
 128 {
 129         struct sk_buff *skb;
 130         struct prio_sched_data *q = qdisc_priv(sch);
 131         int prio;
 132         struct Qdisc *qdisc;
 133
 134         for (prio = 0; prio < q->bands; prio++) {
 135                 /* Check if the target subqueue is available before
 136                  * pulling an skb.  This way we avoid excessive requeues
 137                  * for slower queues.
 138                  */
 139                 if (!__netif_subqueue_stopped(qdisc_dev(sch),
 140                                               (q->mq ? prio : 0))) {
 141                         qdisc = q->queues[prio];
 142                         skb = qdisc->dequeue(qdisc);
 143                         if (skb) {
 144                                 sch->q.qlen--;
 145                                 return skb;
 146                         }
 147                 }
 148         }
 149         return NULL;
 150
 151 }
 152
 153 static struct sk_buff *rr_dequeue(struct Qdisc* sch)
 154 {
 155         struct sk_buff *skb;
 156         struct prio_sched_data *q = qdisc_priv(sch);
 157         struct Qdisc *qdisc;
 158         int bandcount;
 159
 160         /* Only take one pass through the queues.  If nothing is available,
 161          * return nothing.
 162          */
 163         for (bandcount = 0; bandcount < q->bands; bandcount++) {
 164                 /* Check if the target subqueue is available before
 165                  * pulling an skb.  This way we avoid excessive requeues
 166                  * for slower queues.  If the queue is stopped, try the
 167                  * next queue.
 168                  */
 169                 if (!__netif_subqueue_stopped(qdisc_dev(sch),
 170                                               (q->mq ? q->curband : 0))) {
 171                         qdisc = q->queues[q->curband];
 172                         skb = qdisc->dequeue(qdisc);
 173                         if (skb) {
 174                                 sch->q.qlen--;
 175                                 q->curband++;
 176                                 if (q->curband >= q->bands)
 177                                         q->curband = 0;
 178                                 return skb;
 179                         }
 180                 }
 181                 q->curband++;
 182                 if (q->curband >= q->bands)
 183                         q->curband = 0;
 184         }
 185         return NULL;
 186 }
 187
 188 static unsigned int prio_drop(struct Qdisc* sch)
 189 {
 190         struct prio_sched_data *q = qdisc_priv(sch);
 191         int prio;
 192         unsigned int len;
 193         struct Qdisc *qdisc;
 194
 195         for (prio = q->bands-1; prio >= 0; prio--) {
 196                 qdisc = q->queues[prio];
 197                 if (qdisc->ops->drop && (len = qdisc->ops->drop(qdisc)) != 0) {
 198                         sch->q.qlen--;
 199                         return len;
 200                 }
 201         }
 202         return 0;
 203 }
 204
 205
 206 static void
 207 prio_reset(struct Qdisc* sch)
 208 {
 209         int prio;
 210         struct prio_sched_data *q = qdisc_priv(sch);
 211
 212         for (prio=0; prio<q->bands; prio++)
 213                 qdisc_reset(q->queues[prio]);
 214         sch->q.qlen = 0;
 215 }
 216
 217 static void
 218 prio_destroy(struct Qdisc* sch)
 219 {
 220         int prio;
 221         struct prio_sched_data *q = qdisc_priv(sch);
 222
 223         tcf_destroy_chain(&q->filter_list);
 224         for (prio=0; prio<q->bands; prio++)
 225                 qdisc_destroy(q->queues[prio]);
 226 }
 227
 228 static int prio_tune(struct Qdisc *sch, struct nlattr *opt)
 229 {
 230         struct prio_sched_data *q = qdisc_priv(sch);
 231         struct tc_prio_qopt *qopt;
 232         struct nlattr *tb[TCA_PRIO_MAX + 1];
 233         int err;
 234         int i;
 235
 236         err = nla_parse_nested_compat(tb, TCA_PRIO_MAX, opt, NULL, qopt,
 237                                       sizeof(*qopt));
 238         if (err < 0)
 239                 return err;
 240
 241         q->bands = qopt->bands;
 242         /* If we're multiqueue, make sure the number of incoming bands
 243          * matches the number of queues on the device we're associating with.
 244          * If the number of bands requested is zero, then set q->bands to
 245          * dev->egress_subqueue_count.  Also, the root qdisc must be the
 246          * only one that is enabled for multiqueue, since it's the only one
 247          * that interacts with the underlying device.
 248          */
 249         q->mq = nla_get_flag(tb[TCA_PRIO_MQ]);
 250         if (q->mq) {
 251                 if (sch->parent != TC_H_ROOT)
 252                         return -EINVAL;
 253                 if (netif_is_multiqueue(qdisc_dev(sch))) {
 254                         if (q->bands == 0)
 255                                 q->bands = qdisc_dev(sch)->egress_subqueue_count;
 256                         else if (q->bands != qdisc_dev(sch)->egress_subqueue_count)
 257                                 return -EINVAL;
 258                 } else
 259                         return -EOPNOTSUPP;
 260         }
 261
 262         if (q->bands > TCQ_PRIO_BANDS || q->bands < 2)
 263                 return -EINVAL;
 264
 265         for (i=0; i<=TC_PRIO_MAX; i++) {
 266                 if (qopt->priomap[i] >= q->bands)
 267                         return -EINVAL;
 268         }
 269
 270         sch_tree_lock(sch);
 271         memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);
 272
 273         for (i=q->bands; i<TCQ_PRIO_BANDS; i++) {
 274                 struct Qdisc *child = xchg(&q->queues[i], &noop_qdisc);
 275                 if (child != &noop_qdisc) {
 276                         qdisc_tree_decrease_qlen(child, child->q.qlen);
 277                         qdisc_destroy(child);
 278                 }
 279         }
 280         sch_tree_unlock(sch);
 281
 282         for (i=0; i<q->bands; i++) {
 283                 if (q->queues[i] == &noop_qdisc) {
 284                         struct Qdisc *child;
 285                         child = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue,
 286                                                   &pfifo_qdisc_ops,
 287                                                   TC_H_MAKE(sch->handle, i + 1));
 288                         if (child) {
 289                                 sch_tree_lock(sch);
 290                                 child = xchg(&q->queues[i], child);
 291
 292                                 if (child != &noop_qdisc) {
 293                                         qdisc_tree_decrease_qlen(child,
 294                                                                  child->q.qlen);
 295                                         qdisc_destroy(child);
 296                                 }
 297                                 sch_tree_unlock(sch);
 298                         }
 299                 }
 300         }
 301         return 0;
 302 }
 303
 304 static int prio_init(struct Qdisc *sch, struct nlattr *opt)
 305 {
 306         struct prio_sched_data *q = qdisc_priv(sch);
 307         int i;
 308
 309         for (i=0; i<TCQ_PRIO_BANDS; i++)
 310                 q->queues[i] = &noop_qdisc;
 311
 312         if (opt == NULL) {
 313                 return -EINVAL;
 314         } else {
 315                 int err;
 316
 317                 if ((err= prio_tune(sch, opt)) != 0)
 318                         return err;
 319         }
 320         return 0;
 321 }
 322
 323 static int prio_dump(struct Qdisc *sch, struct sk_buff *skb)
 324 {
 325         struct prio_sched_data *q = qdisc_priv(sch);
 326         unsigned char *b = skb_tail_pointer(skb);
 327         struct nlattr *nest;
 328         struct tc_prio_qopt opt;
 329
 330         opt.bands = q->bands;
 331         memcpy(&opt.priomap, q->prio2band, TC_PRIO_MAX+1);
 332
 333         nest = nla_nest_compat_start(skb, TCA_OPTIONS, sizeof(opt), &opt);
 334         if (nest == NULL)
 335                 goto nla_put_failure;
 336         if (q->mq) {
 337                 if (nla_put_flag(skb, TCA_PRIO_MQ) < 0)
 338                         goto nla_put_failure;
 339         }
 340         nla_nest_compat_end(skb, nest);
 341
 342         return skb->len;
 343
 344 nla_put_failure:
 345         nlmsg_trim(skb, b);
 346         return -1;
 347 }
 348
 349 static int prio_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 350                       struct Qdisc **old)
 351 {
 352         struct prio_sched_data *q = qdisc_priv(sch);
 353         unsigned long band = arg - 1;
 354
 355         if (band >= q->bands)
 356                 return -EINVAL;
 357
 358         if (new == NULL)
 359                 new = &noop_qdisc;
 360
 361         sch_tree_lock(sch);
 362         *old = q->queues[band];
 363         q->queues[band] = new;
 364         qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
 365         qdisc_reset(*old);
 366         sch_tree_unlock(sch);
 367
 368         return 0;
 369 }
 370
 371 static struct Qdisc *
 372 prio_leaf(struct Qdisc *sch, unsigned long arg)
 373 {
 374         struct prio_sched_data *q = qdisc_priv(sch);
 375         unsigned long band = arg - 1;
 376
 377         if (band >= q->bands)
 378                 return NULL;
 379
 380         return q->queues[band];
 381 }
 382
 383 static unsigned long prio_get(struct Qdisc *sch, u32 classid)
 384 {
 385         struct prio_sched_data *q = qdisc_priv(sch);
 386         unsigned long band = TC_H_MIN(classid);
 387
 388         if (band - 1 >= q->bands)
 389                 return 0;
 390         return band;
 391 }
 392
 393 static unsigned long prio_bind(struct Qdisc *sch, unsigned long parent, u32 classid)
 394 {
 395         return prio_get(sch, classid);
 396 }
 397
 398
 399 static void prio_put(struct Qdisc *q, unsigned long cl)
 400 {
 401         return;
 402 }
 403
 404 static int prio_change(struct Qdisc *sch, u32 handle, u32 parent, struct nlattr **tca, unsigned long *arg)
 405 {
 406         unsigned long cl = *arg;
 407         struct prio_sched_data *q = qdisc_priv(sch);
 408
 409         if (cl - 1 > q->bands)
 410                 return -ENOENT;
 411         return 0;
 412 }
 413
 414 static int prio_delete(struct Qdisc *sch, unsigned long cl)
 415 {
 416         struct prio_sched_data *q = qdisc_priv(sch);
 417         if (cl - 1 > q->bands)
 418                 return -ENOENT;
 419         return 0;
 420 }
 421
 422
 423 static int prio_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *skb,
 424                            struct tcmsg *tcm)
 425 {
 426         struct prio_sched_data *q = qdisc_priv(sch);
 427
 428         if (cl - 1 > q->bands)
 429                 return -ENOENT;
 430         tcm->tcm_handle |= TC_H_MIN(cl);
 431         if (q->queues[cl-1])
 432                 tcm->tcm_info = q->queues[cl-1]->handle;
 433         return 0;
 434 }
 435
 436 static int prio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 437                                  struct gnet_dump *d)
 438 {
 439         struct prio_sched_data *q = qdisc_priv(sch);
 440         struct Qdisc *cl_q;
 441
 442         cl_q = q->queues[cl - 1];
 443         if (gnet_stats_copy_basic(d, &cl_q->bstats) < 0 ||
 444             gnet_stats_copy_queue(d, &cl_q->qstats) < 0)
 445                 return -1;
 446
 447         return 0;
 448 }
 449
 450 static void prio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 451 {
 452         struct prio_sched_data *q = qdisc_priv(sch);
 453         int prio;
 454
 455         if (arg->stop)
 456                 return;
 457
 458         for (prio = 0; prio < q->bands; prio++) {
 459                 if (arg->count < arg->skip) {
 460                         arg->count++;
 461                         continue;
 462                 }
 463                 if (arg->fn(sch, prio+1, arg) < 0) {
 464                         arg->stop = 1;
 465                         break;
 466                 }
 467                 arg->count++;
 468         }
 469 }
 470
 471 static struct tcf_proto ** prio_find_tcf(struct Qdisc *sch, unsigned long cl)
 472 {
 473         struct prio_sched_data *q = qdisc_priv(sch);
 474
 475         if (cl)
 476                 return NULL;
 477         return &q->filter_list;
 478 }
 479
 480 static const struct Qdisc_class_ops prio_class_ops = {
 481         .graft          =       prio_graft,
 482         .leaf           =       prio_leaf,
 483         .get            =       prio_get,
 484         .put            =       prio_put,
 485         .change         =       prio_change,
 486         .delete         =       prio_delete,
 487         .walk           =       prio_walk,
 488         .tcf_chain      =       prio_find_tcf,
 489         .bind_tcf       =       prio_bind,
 490         .unbind_tcf     =       prio_put,
 491         .dump           =       prio_dump_class,
 492         .dump_stats     =       prio_dump_class_stats,
 493 };
 494
 495 static struct Qdisc_ops prio_qdisc_ops __read_mostly = {
 496         .next           =       NULL,
 497         .cl_ops         =       &prio_class_ops,
 498         .id             =       "prio",
 499         .priv_size      =       sizeof(struct prio_sched_data),
 500         .enqueue        =       prio_enqueue,
 501         .dequeue        =       prio_dequeue,
 502         .requeue        =       prio_requeue,
 503         .drop           =       prio_drop,
 504         .init           =       prio_init,
 505         .reset          =       prio_reset,
 506         .destroy        =       prio_destroy,
 507         .change         =       prio_tune,
 508         .dump           =       prio_dump,
 509         .owner          =       THIS_MODULE,
 510 };
 511
 512 static struct Qdisc_ops rr_qdisc_ops __read_mostly = {
 513         .next           =       NULL,
 514         .cl_ops         =       &prio_class_ops,
 515         .id             =       "rr",
 516         .priv_size      =       sizeof(struct prio_sched_data),
 517         .enqueue        =       prio_enqueue,
 518         .dequeue        =       rr_dequeue,
 519         .requeue        =       prio_requeue,
 520         .drop           =       prio_drop,
 521         .init           =       prio_init,
 522         .reset          =       prio_reset,
 523         .destroy        =       prio_destroy,
 524         .change         =       prio_tune,
 525         .dump           =       prio_dump,
 526         .owner          =       THIS_MODULE,
 527 };
 528
 529 static int __init prio_module_init(void)
 530 {
 531         int err;
 532
 533         err = register_qdisc(&prio_qdisc_ops);
 534         if (err < 0)
 535                 return err;
 536         err = register_qdisc(&rr_qdisc_ops);
 537         if (err < 0)
 538                 unregister_qdisc(&prio_qdisc_ops);
 539         return err;
 540 }
 541
 542 static void __exit prio_module_exit(void)
 543 {
 544         unregister_qdisc(&prio_qdisc_ops);
 545         unregister_qdisc(&rr_qdisc_ops);
 546 }
 547
 548 module_init(prio_module_init)
 549 module_exit(prio_module_exit)
 550
 551 MODULE_LICENSE("GPL");
 552 MODULE_ALIAS("sch_rr");