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 nlattr *opt)
 228 {
 229         struct prio_sched_data *q = qdisc_priv(sch);
 230         struct tc_prio_qopt *qopt;
 231         struct nlattr *tb[TCA_PRIO_MAX + 1];
 232         int err;
 233         int i;
 234
 235         err = nla_parse_nested_compat(tb, TCA_PRIO_MAX, opt, NULL, qopt,
 236                                       sizeof(*qopt));
 237         if (err < 0)
 238                 return err;
 239
 240         q->bands = qopt->bands;
 241         /* If we're multiqueue, make sure the number of incoming bands
 242          * matches the number of queues on the device we're associating with.
 243          * If the number of bands requested is zero, then set q->bands to
 244          * dev->egress_subqueue_count.  Also, the root qdisc must be the
 245          * only one that is enabled for multiqueue, since it's the only one
 246          * that interacts with the underlying device.
 247          */
 248         q->mq = nla_get_flag(tb[TCA_PRIO_MQ]);
 249         if (q->mq) {
 250                 if (sch->parent != TC_H_ROOT)
 251                         return -EINVAL;
 252                 if (netif_is_multiqueue(sch->dev)) {
 253                         if (q->bands == 0)
 254                                 q->bands = sch->dev->egress_subqueue_count;
 255                         else if (q->bands != sch->dev->egress_subqueue_count)
 256                                 return -EINVAL;
 257                 } else
 258                         return -EOPNOTSUPP;
 259         }
 260
 261         if (q->bands > TCQ_PRIO_BANDS || q->bands < 2)
 262                 return -EINVAL;
 263
 264         for (i=0; i<=TC_PRIO_MAX; i++) {
 265                 if (qopt->priomap[i] >= q->bands)
 266                         return -EINVAL;
 267         }
 268
 269         sch_tree_lock(sch);
 270         memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);
 271
 272         for (i=q->bands; i<TCQ_PRIO_BANDS; i++) {
 273                 struct Qdisc *child = xchg(&q->queues[i], &noop_qdisc);
 274                 if (child != &noop_qdisc) {
 275                         qdisc_tree_decrease_qlen(child, child->q.qlen);
 276                         qdisc_destroy(child);
 277                 }
 278         }
 279         sch_tree_unlock(sch);
 280
 281         for (i=0; i<q->bands; i++) {
 282                 if (q->queues[i] == &noop_qdisc) {
 283                         struct Qdisc *child;
 284                         child = qdisc_create_dflt(sch->dev, &pfifo_qdisc_ops,
 285                                                   TC_H_MAKE(sch->handle, i + 1));
 286                         if (child) {
 287                                 sch_tree_lock(sch);
 288                                 child = xchg(&q->queues[i], child);
 289
 290                                 if (child != &noop_qdisc) {
 291                                         qdisc_tree_decrease_qlen(child,
 292                                                                  child->q.qlen);
 293                                         qdisc_destroy(child);
 294                                 }
 295                                 sch_tree_unlock(sch);
 296                         }
 297                 }
 298         }
 299         return 0;
 300 }
 301
 302 static int prio_init(struct Qdisc *sch, struct nlattr *opt)
 303 {
 304         struct prio_sched_data *q = qdisc_priv(sch);
 305         int i;
 306
 307         for (i=0; i<TCQ_PRIO_BANDS; i++)
 308                 q->queues[i] = &noop_qdisc;
 309
 310         if (opt == NULL) {
 311                 return -EINVAL;
 312         } else {
 313                 int err;
 314
 315                 if ((err= prio_tune(sch, opt)) != 0)
 316                         return err;
 317         }
 318         return 0;
 319 }
 320
 321 static int prio_dump(struct Qdisc *sch, struct sk_buff *skb)
 322 {
 323         struct prio_sched_data *q = qdisc_priv(sch);
 324         unsigned char *b = skb_tail_pointer(skb);
 325         struct nlattr *nest;
 326         struct tc_prio_qopt opt;
 327
 328         opt.bands = q->bands;
 329         memcpy(&opt.priomap, q->prio2band, TC_PRIO_MAX+1);
 330
 331         nest = nla_nest_compat_start(skb, TCA_OPTIONS, sizeof(opt), &opt);
 332         if (nest == NULL)
 333                 goto nla_put_failure;
 334         if (q->mq) {
 335                 if (nla_put_flag(skb, TCA_PRIO_MQ) < 0)
 336                         goto nla_put_failure;
 337         }
 338         nla_nest_compat_end(skb, nest);
 339
 340         return skb->len;
 341
 342 nla_put_failure:
 343         nlmsg_trim(skb, b);
 344         return -1;
 345 }
 346
 347 static int prio_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 348                       struct Qdisc **old)
 349 {
 350         struct prio_sched_data *q = qdisc_priv(sch);
 351         unsigned long band = arg - 1;
 352
 353         if (band >= q->bands)
 354                 return -EINVAL;
 355
 356         if (new == NULL)
 357                 new = &noop_qdisc;
 358
 359         sch_tree_lock(sch);
 360         *old = q->queues[band];
 361         q->queues[band] = new;
 362         qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
 363         qdisc_reset(*old);
 364         sch_tree_unlock(sch);
 365
 366         return 0;
 367 }
 368
 369 static struct Qdisc *
 370 prio_leaf(struct Qdisc *sch, unsigned long arg)
 371 {
 372         struct prio_sched_data *q = qdisc_priv(sch);
 373         unsigned long band = arg - 1;
 374
 375         if (band >= q->bands)
 376                 return NULL;
 377
 378         return q->queues[band];
 379 }
 380
 381 static unsigned long prio_get(struct Qdisc *sch, u32 classid)
 382 {
 383         struct prio_sched_data *q = qdisc_priv(sch);
 384         unsigned long band = TC_H_MIN(classid);
 385
 386         if (band - 1 >= q->bands)
 387                 return 0;
 388         return band;
 389 }
 390
 391 static unsigned long prio_bind(struct Qdisc *sch, unsigned long parent, u32 classid)
 392 {
 393         return prio_get(sch, classid);
 394 }
 395
 396
 397 static void prio_put(struct Qdisc *q, unsigned long cl)
 398 {
 399         return;
 400 }
 401
 402 static int prio_change(struct Qdisc *sch, u32 handle, u32 parent, struct nlattr **tca, unsigned long *arg)
 403 {
 404         unsigned long cl = *arg;
 405         struct prio_sched_data *q = qdisc_priv(sch);
 406
 407         if (cl - 1 > q->bands)
 408                 return -ENOENT;
 409         return 0;
 410 }
 411
 412 static int prio_delete(struct Qdisc *sch, unsigned long cl)
 413 {
 414         struct prio_sched_data *q = qdisc_priv(sch);
 415         if (cl - 1 > q->bands)
 416                 return -ENOENT;
 417         return 0;
 418 }
 419
 420
 421 static int prio_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *skb,
 422                            struct tcmsg *tcm)
 423 {
 424         struct prio_sched_data *q = qdisc_priv(sch);
 425
 426         if (cl - 1 > q->bands)
 427                 return -ENOENT;
 428         tcm->tcm_handle |= TC_H_MIN(cl);
 429         if (q->queues[cl-1])
 430                 tcm->tcm_info = q->queues[cl-1]->handle;
 431         return 0;
 432 }
 433
 434 static int prio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 435                                  struct gnet_dump *d)
 436 {
 437         struct prio_sched_data *q = qdisc_priv(sch);
 438         struct Qdisc *cl_q;
 439
 440         cl_q = q->queues[cl - 1];
 441         if (gnet_stats_copy_basic(d, &cl_q->bstats) < 0 ||
 442             gnet_stats_copy_queue(d, &cl_q->qstats) < 0)
 443                 return -1;
 444
 445         return 0;
 446 }
 447
 448 static void prio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 449 {
 450         struct prio_sched_data *q = qdisc_priv(sch);
 451         int prio;
 452
 453         if (arg->stop)
 454                 return;
 455
 456         for (prio = 0; prio < q->bands; prio++) {
 457                 if (arg->count < arg->skip) {
 458                         arg->count++;
 459                         continue;
 460                 }
 461                 if (arg->fn(sch, prio+1, arg) < 0) {
 462                         arg->stop = 1;
 463                         break;
 464                 }
 465                 arg->count++;
 466         }
 467 }
 468
 469 static struct tcf_proto ** prio_find_tcf(struct Qdisc *sch, unsigned long cl)
 470 {
 471         struct prio_sched_data *q = qdisc_priv(sch);
 472
 473         if (cl)
 474                 return NULL;
 475         return &q->filter_list;
 476 }
 477
 478 static const struct Qdisc_class_ops prio_class_ops = {
 479         .graft          =       prio_graft,
 480         .leaf           =       prio_leaf,
 481         .get            =       prio_get,
 482         .put            =       prio_put,
 483         .change         =       prio_change,
 484         .delete         =       prio_delete,
 485         .walk           =       prio_walk,
 486         .tcf_chain      =       prio_find_tcf,
 487         .bind_tcf       =       prio_bind,
 488         .unbind_tcf     =       prio_put,
 489         .dump           =       prio_dump_class,
 490         .dump_stats     =       prio_dump_class_stats,
 491 };
 492
 493 static struct Qdisc_ops prio_qdisc_ops __read_mostly = {
 494         .next           =       NULL,
 495         .cl_ops         =       &prio_class_ops,
 496         .id             =       "prio",
 497         .priv_size      =       sizeof(struct prio_sched_data),
 498         .enqueue        =       prio_enqueue,
 499         .dequeue        =       prio_dequeue,
 500         .requeue        =       prio_requeue,
 501         .drop           =       prio_drop,
 502         .init           =       prio_init,
 503         .reset          =       prio_reset,
 504         .destroy        =       prio_destroy,
 505         .change         =       prio_tune,
 506         .dump           =       prio_dump,
 507         .owner          =       THIS_MODULE,
 508 };
 509
 510 static struct Qdisc_ops rr_qdisc_ops __read_mostly = {
 511         .next           =       NULL,
 512         .cl_ops         =       &prio_class_ops,
 513         .id             =       "rr",
 514         .priv_size      =       sizeof(struct prio_sched_data),
 515         .enqueue        =       prio_enqueue,
 516         .dequeue        =       rr_dequeue,
 517         .requeue        =       prio_requeue,
 518         .drop           =       prio_drop,
 519         .init           =       prio_init,
 520         .reset          =       prio_reset,
 521         .destroy        =       prio_destroy,
 522         .change         =       prio_tune,
 523         .dump           =       prio_dump,
 524         .owner          =       THIS_MODULE,
 525 };
 526
 527 static int __init prio_module_init(void)
 528 {
 529         int err;
 530
 531         err = register_qdisc(&prio_qdisc_ops);
 532         if (err < 0)
 533                 return err;
 534         err = register_qdisc(&rr_qdisc_ops);
 535         if (err < 0)
 536                 unregister_qdisc(&prio_qdisc_ops);
 537         return err;
 538 }
 539
 540 static void __exit prio_module_exit(void)
 541 {
 542         unregister_qdisc(&prio_qdisc_ops);
 543         unregister_qdisc(&rr_qdisc_ops);
 544 }
 545
 546 module_init(prio_module_init)
 547 module_exit(prio_module_exit)
 548
 549 MODULE_LICENSE("GPL");
 550 MODULE_ALIAS("sch_rr");