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(sch->dev, (q->mq ? prio : 0))) {
 140                         qdisc = q->queues[prio];
 141                         skb = qdisc->dequeue(qdisc);
 142                         if (skb) {
 143                                 sch->q.qlen--;
 144                                 return skb;
 145                         }
 146                 }
 147         }
 148         return NULL;
 149
 150 }
 151
 152 static struct sk_buff *rr_dequeue(struct Qdisc* sch)
 153 {
 154         struct sk_buff *skb;
 155         struct prio_sched_data *q = qdisc_priv(sch);
 156         struct Qdisc *qdisc;
 157         int bandcount;
 158
 159         /* Only take one pass through the queues.  If nothing is available,
 160          * return nothing.
 161          */
 162         for (bandcount = 0; bandcount < q->bands; bandcount++) {
 163                 /* Check if the target subqueue is available before
 164                  * pulling an skb.  This way we avoid excessive requeues
 165                  * for slower queues.  If the queue is stopped, try the
 166                  * next queue.
 167                  */
 168                 if (!__netif_subqueue_stopped(sch->dev,
 169                                             (q->mq ? q->curband : 0))) {
 170                         qdisc = q->queues[q->curband];
 171                         skb = qdisc->dequeue(qdisc);
 172                         if (skb) {
 173                                 sch->q.qlen--;
 174                                 q->curband++;
 175                                 if (q->curband >= q->bands)
 176                                         q->curband = 0;
 177                                 return skb;
 178                         }
 179                 }
 180                 q->curband++;
 181                 if (q->curband >= q->bands)
 182                         q->curband = 0;
 183         }
 184         return NULL;
 185 }
 186
 187 static unsigned int prio_drop(struct Qdisc* sch)
 188 {
 189         struct prio_sched_data *q = qdisc_priv(sch);
 190         int prio;
 191         unsigned int len;
 192         struct Qdisc *qdisc;
 193
 194         for (prio = q->bands-1; prio >= 0; prio--) {
 195                 qdisc = q->queues[prio];
 196                 if (qdisc->ops->drop && (len = qdisc->ops->drop(qdisc)) != 0) {
 197                         sch->q.qlen--;
 198                         return len;
 199                 }
 200         }
 201         return 0;
 202 }
 203
 204
 205 static void
 206 prio_reset(struct Qdisc* sch)
 207 {
 208         int prio;
 209         struct prio_sched_data *q = qdisc_priv(sch);
 210
 211         for (prio=0; prio<q->bands; prio++)
 212                 qdisc_reset(q->queues[prio]);
 213         sch->q.qlen = 0;
 214 }
 215
 216 static void
 217 prio_destroy(struct Qdisc* sch)
 218 {
 219         int prio;
 220         struct prio_sched_data *q = qdisc_priv(sch);
 221
 222         tcf_destroy_chain(q->filter_list);
 223         for (prio=0; prio<q->bands; prio++)
 224                 qdisc_destroy(q->queues[prio]);
 225 }
 226
 227 static int prio_tune(struct Qdisc *sch, struct rtattr *opt)
 228 {
 229         struct prio_sched_data *q = qdisc_priv(sch);
 230         struct tc_prio_qopt *qopt;
 231         struct rtattr *tb[TCA_PRIO_MAX];
 232         int i;
 233
 234         if (rtattr_parse_nested_compat(tb, TCA_PRIO_MAX, opt, qopt,
 235                                        sizeof(*qopt)))
 236                 return -EINVAL;
 237         q->bands = qopt->bands;
 238         /* If we're multiqueue, make sure the number of incoming bands
 239          * matches the number of queues on the device we're associating with.
 240          * If the number of bands requested is zero, then set q->bands to
 241          * dev->egress_subqueue_count.  Also, the root qdisc must be the
 242          * only one that is enabled for multiqueue, since it's the only one
 243          * that interacts with the underlying device.
 244          */
 245         q->mq = RTA_GET_FLAG(tb[TCA_PRIO_MQ - 1]);
 246         if (q->mq) {
 247                 if (sch->parent != TC_H_ROOT)
 248                         return -EINVAL;
 249                 if (netif_is_multiqueue(sch->dev)) {
 250                         if (q->bands == 0)
 251                                 q->bands = sch->dev->egress_subqueue_count;
 252                         else if (q->bands != sch->dev->egress_subqueue_count)
 253                                 return -EINVAL;
 254                 } else
 255                         return -EOPNOTSUPP;
 256         }
 257
 258         if (q->bands > TCQ_PRIO_BANDS || q->bands < 2)
 259                 return -EINVAL;
 260
 261         for (i=0; i<=TC_PRIO_MAX; i++) {
 262                 if (qopt->priomap[i] >= q->bands)
 263                         return -EINVAL;
 264         }
 265
 266         sch_tree_lock(sch);
 267         memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);
 268
 269         for (i=q->bands; i<TCQ_PRIO_BANDS; i++) {
 270                 struct Qdisc *child = xchg(&q->queues[i], &noop_qdisc);
 271                 if (child != &noop_qdisc) {
 272                         qdisc_tree_decrease_qlen(child, child->q.qlen);
 273                         qdisc_destroy(child);
 274                 }
 275         }
 276         sch_tree_unlock(sch);
 277
 278         for (i=0; i<q->bands; i++) {
 279                 if (q->queues[i] == &noop_qdisc) {
 280                         struct Qdisc *child;
 281                         child = qdisc_create_dflt(sch->dev, &pfifo_qdisc_ops,
 282                                                   TC_H_MAKE(sch->handle, i + 1));
 283                         if (child) {
 284                                 sch_tree_lock(sch);
 285                                 child = xchg(&q->queues[i], child);
 286
 287                                 if (child != &noop_qdisc) {
 288                                         qdisc_tree_decrease_qlen(child,
 289                                                                  child->q.qlen);
 290                                         qdisc_destroy(child);
 291                                 }
 292                                 sch_tree_unlock(sch);
 293                         }
 294                 }
 295         }
 296         return 0;
 297 }
 298
 299 static int prio_init(struct Qdisc *sch, struct rtattr *opt)
 300 {
 301         struct prio_sched_data *q = qdisc_priv(sch);
 302         int i;
 303
 304         for (i=0; i<TCQ_PRIO_BANDS; i++)
 305                 q->queues[i] = &noop_qdisc;
 306
 307         if (opt == NULL) {
 308                 return -EINVAL;
 309         } else {
 310                 int err;
 311
 312                 if ((err= prio_tune(sch, opt)) != 0)
 313                         return err;
 314         }
 315         return 0;
 316 }
 317
 318 static int prio_dump(struct Qdisc *sch, struct sk_buff *skb)
 319 {
 320         struct prio_sched_data *q = qdisc_priv(sch);
 321         unsigned char *b = skb_tail_pointer(skb);
 322         struct rtattr *nest;
 323         struct tc_prio_qopt opt;
 324
 325         opt.bands = q->bands;
 326         memcpy(&opt.priomap, q->prio2band, TC_PRIO_MAX+1);
 327
 328         nest = RTA_NEST_COMPAT(skb, TCA_OPTIONS, sizeof(opt), &opt);
 329         if (q->mq)
 330                 RTA_PUT_FLAG(skb, TCA_PRIO_MQ);
 331         RTA_NEST_COMPAT_END(skb, nest);
 332
 333         return skb->len;
 334
 335 rtattr_failure:
 336         nlmsg_trim(skb, b);
 337         return -1;
 338 }
 339
 340 static int prio_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 341                       struct Qdisc **old)
 342 {
 343         struct prio_sched_data *q = qdisc_priv(sch);
 344         unsigned long band = arg - 1;
 345
 346         if (band >= q->bands)
 347                 return -EINVAL;
 348
 349         if (new == NULL)
 350                 new = &noop_qdisc;
 351
 352         sch_tree_lock(sch);
 353         *old = q->queues[band];
 354         q->queues[band] = new;
 355         qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
 356         qdisc_reset(*old);
 357         sch_tree_unlock(sch);
 358
 359         return 0;
 360 }
 361
 362 static struct Qdisc *
 363 prio_leaf(struct Qdisc *sch, unsigned long arg)
 364 {
 365         struct prio_sched_data *q = qdisc_priv(sch);
 366         unsigned long band = arg - 1;
 367
 368         if (band >= q->bands)
 369                 return NULL;
 370
 371         return q->queues[band];
 372 }
 373
 374 static unsigned long prio_get(struct Qdisc *sch, u32 classid)
 375 {
 376         struct prio_sched_data *q = qdisc_priv(sch);
 377         unsigned long band = TC_H_MIN(classid);
 378
 379         if (band - 1 >= q->bands)
 380                 return 0;
 381         return band;
 382 }
 383
 384 static unsigned long prio_bind(struct Qdisc *sch, unsigned long parent, u32 classid)
 385 {
 386         return prio_get(sch, classid);
 387 }
 388
 389
 390 static void prio_put(struct Qdisc *q, unsigned long cl)
 391 {
 392         return;
 393 }
 394
 395 static int prio_change(struct Qdisc *sch, u32 handle, u32 parent, struct rtattr **tca, unsigned long *arg)
 396 {
 397         unsigned long cl = *arg;
 398         struct prio_sched_data *q = qdisc_priv(sch);
 399
 400         if (cl - 1 > q->bands)
 401                 return -ENOENT;
 402         return 0;
 403 }
 404
 405 static int prio_delete(struct Qdisc *sch, unsigned long cl)
 406 {
 407         struct prio_sched_data *q = qdisc_priv(sch);
 408         if (cl - 1 > q->bands)
 409                 return -ENOENT;
 410         return 0;
 411 }
 412
 413
 414 static int prio_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *skb,
 415                            struct tcmsg *tcm)
 416 {
 417         struct prio_sched_data *q = qdisc_priv(sch);
 418
 419         if (cl - 1 > q->bands)
 420                 return -ENOENT;
 421         tcm->tcm_handle |= TC_H_MIN(cl);
 422         if (q->queues[cl-1])
 423                 tcm->tcm_info = q->queues[cl-1]->handle;
 424         return 0;
 425 }
 426
 427 static int prio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 428                                  struct gnet_dump *d)
 429 {
 430         struct prio_sched_data *q = qdisc_priv(sch);
 431         struct Qdisc *cl_q;
 432
 433         cl_q = q->queues[cl - 1];
 434         if (gnet_stats_copy_basic(d, &cl_q->bstats) < 0 ||
 435             gnet_stats_copy_queue(d, &cl_q->qstats) < 0)
 436                 return -1;
 437
 438         return 0;
 439 }
 440
 441 static void prio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 442 {
 443         struct prio_sched_data *q = qdisc_priv(sch);
 444         int prio;
 445
 446         if (arg->stop)
 447                 return;
 448
 449         for (prio = 0; prio < q->bands; prio++) {
 450                 if (arg->count < arg->skip) {
 451                         arg->count++;
 452                         continue;
 453                 }
 454                 if (arg->fn(sch, prio+1, arg) < 0) {
 455                         arg->stop = 1;
 456                         break;
 457                 }
 458                 arg->count++;
 459         }
 460 }
 461
 462 static struct tcf_proto ** prio_find_tcf(struct Qdisc *sch, unsigned long cl)
 463 {
 464         struct prio_sched_data *q = qdisc_priv(sch);
 465
 466         if (cl)
 467                 return NULL;
 468         return &q->filter_list;
 469 }
 470
 471 static const struct Qdisc_class_ops prio_class_ops = {
 472         .graft          =       prio_graft,
 473         .leaf           =       prio_leaf,
 474         .get            =       prio_get,
 475         .put            =       prio_put,
 476         .change         =       prio_change,
 477         .delete         =       prio_delete,
 478         .walk           =       prio_walk,
 479         .tcf_chain      =       prio_find_tcf,
 480         .bind_tcf       =       prio_bind,
 481         .unbind_tcf     =       prio_put,
 482         .dump           =       prio_dump_class,
 483         .dump_stats     =       prio_dump_class_stats,
 484 };
 485
 486 static struct Qdisc_ops prio_qdisc_ops __read_mostly = {
 487         .next           =       NULL,
 488         .cl_ops         =       &prio_class_ops,
 489         .id             =       "prio",
 490         .priv_size      =       sizeof(struct prio_sched_data),
 491         .enqueue        =       prio_enqueue,
 492         .dequeue        =       prio_dequeue,
 493         .requeue        =       prio_requeue,
 494         .drop           =       prio_drop,
 495         .init           =       prio_init,
 496         .reset          =       prio_reset,
 497         .destroy        =       prio_destroy,
 498         .change         =       prio_tune,
 499         .dump           =       prio_dump,
 500         .owner          =       THIS_MODULE,
 501 };
 502
 503 static struct Qdisc_ops rr_qdisc_ops __read_mostly = {
 504         .next           =       NULL,
 505         .cl_ops         =       &prio_class_ops,
 506         .id             =       "rr",
 507         .priv_size      =       sizeof(struct prio_sched_data),
 508         .enqueue        =       prio_enqueue,
 509         .dequeue        =       rr_dequeue,
 510         .requeue        =       prio_requeue,
 511         .drop           =       prio_drop,
 512         .init           =       prio_init,
 513         .reset          =       prio_reset,
 514         .destroy        =       prio_destroy,
 515         .change         =       prio_tune,
 516         .dump           =       prio_dump,
 517         .owner          =       THIS_MODULE,
 518 };
 519
 520 static int __init prio_module_init(void)
 521 {
 522         int err;
 523
 524         err = register_qdisc(&prio_qdisc_ops);
 525         if (err < 0)
 526                 return err;
 527         err = register_qdisc(&rr_qdisc_ops);
 528         if (err < 0)
 529                 unregister_qdisc(&prio_qdisc_ops);
 530         return err;
 531 }
 532
 533 static void __exit prio_module_exit(void)
 534 {
 535         unregister_qdisc(&prio_qdisc_ops);
 536         unregister_qdisc(&rr_qdisc_ops);
 537 }
 538
 539 module_init(prio_module_init)
 540 module_exit(prio_module_exit)
 541
 542 MODULE_LICENSE("GPL");
 543 MODULE_ALIAS("sch_rr");