net/sched/sch_drr.c

   1 /*
   2  * net/sched/sch_drr.c         Deficit Round Robin scheduler
   3  *
   4  * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * version 2 as published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/init.h>
  13 #include <linux/errno.h>
  14 #include <linux/netdevice.h>
  15 #include <linux/pkt_sched.h>
  16 #include <net/sch_generic.h>
  17 #include <net/pkt_sched.h>
  18 #include <net/pkt_cls.h>
  19
  20 struct drr_class {
  21         struct Qdisc_class_common       common;
  22         unsigned int                    refcnt;
  23         unsigned int                    filter_cnt;
  24
  25         struct gnet_stats_basic         bstats;
  26         struct gnet_stats_queue         qstats;
  27         struct gnet_stats_rate_est      rate_est;
  28         struct list_head                alist;
  29         struct Qdisc                    *qdisc;
  30
  31         u32                             quantum;
  32         u32                             deficit;
  33 };
  34
  35 struct drr_sched {
  36         struct list_head                active;
  37         struct tcf_proto                *filter_list;
  38         struct Qdisc_class_hash         clhash;
  39 };
  40
  41 static struct drr_class *drr_find_class(struct Qdisc *sch, u32 classid)
  42 {
  43         struct drr_sched *q = qdisc_priv(sch);
  44         struct Qdisc_class_common *clc;
  45
  46         clc = qdisc_class_find(&q->clhash, classid);
  47         if (clc == NULL)
  48                 return NULL;
  49         return container_of(clc, struct drr_class, common);
  50 }
  51
  52 static void drr_purge_queue(struct drr_class *cl)
  53 {
  54         unsigned int len = cl->qdisc->q.qlen;
  55
  56         qdisc_reset(cl->qdisc);
  57         qdisc_tree_decrease_qlen(cl->qdisc, len);
  58 }
  59
  60 static const struct nla_policy drr_policy[TCA_DRR_MAX + 1] = {
  61         [TCA_DRR_QUANTUM]       = { .type = NLA_U32 },
  62 };
  63
  64 static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
  65                             struct nlattr **tca, unsigned long *arg)
  66 {
  67         struct drr_sched *q = qdisc_priv(sch);
  68         struct drr_class *cl = (struct drr_class *)*arg;
  69         struct nlattr *opt = tca[TCA_OPTIONS];
  70         struct nlattr *tb[TCA_DRR_MAX + 1];
  71         u32 quantum;
  72         int err;
  73
  74         if (!opt)
  75                 return -EINVAL;
  76
  77         err = nla_parse_nested(tb, TCA_DRR_MAX, opt, drr_policy);
  78         if (err < 0)
  79                 return err;
  80
  81         if (tb[TCA_DRR_QUANTUM]) {
  82                 quantum = nla_get_u32(tb[TCA_DRR_QUANTUM]);
  83                 if (quantum == 0)
  84                         return -EINVAL;
  85         } else
  86                 quantum = psched_mtu(qdisc_dev(sch));
  87
  88         if (cl != NULL) {
  89                 if (tca[TCA_RATE]) {
  90                         err = gen_replace_estimator(&cl->bstats, &cl->rate_est,
  91                                                     qdisc_root_sleeping_lock(sch),
  92                                                     tca[TCA_RATE]);
  93                         if (err)
  94                                 return err;
  95                 }
  96
  97                 sch_tree_lock(sch);
  98                 if (tb[TCA_DRR_QUANTUM])
  99                         cl->quantum = quantum;
 100                 sch_tree_unlock(sch);
 101
 102                 return 0;
 103         }
 104
 105         cl = kzalloc(sizeof(struct drr_class), GFP_KERNEL);
 106         if (cl == NULL)
 107                 return -ENOBUFS;
 108
 109         cl->refcnt         = 1;
 110         cl->common.classid = classid;
 111         cl->quantum        = quantum;
 112         cl->qdisc          = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue,
 113                                                &pfifo_qdisc_ops, classid);
 114         if (cl->qdisc == NULL)
 115                 cl->qdisc = &noop_qdisc;
 116
 117         if (tca[TCA_RATE]) {
 118                 err = gen_replace_estimator(&cl->bstats, &cl->rate_est,
 119                                             qdisc_root_sleeping_lock(sch),
 120                                             tca[TCA_RATE]);
 121                 if (err) {
 122                         qdisc_destroy(cl->qdisc);
 123                         kfree(cl);
 124                         return err;
 125                 }
 126         }
 127
 128         sch_tree_lock(sch);
 129         qdisc_class_hash_insert(&q->clhash, &cl->common);
 130         sch_tree_unlock(sch);
 131
 132         qdisc_class_hash_grow(sch, &q->clhash);
 133
 134         *arg = (unsigned long)cl;
 135         return 0;
 136 }
 137
 138 static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl)
 139 {
 140         gen_kill_estimator(&cl->bstats, &cl->rate_est);
 141         qdisc_destroy(cl->qdisc);
 142         kfree(cl);
 143 }
 144
 145 static int drr_delete_class(struct Qdisc *sch, unsigned long arg)
 146 {
 147         struct drr_sched *q = qdisc_priv(sch);
 148         struct drr_class *cl = (struct drr_class *)arg;
 149
 150         if (cl->filter_cnt > 0)
 151                 return -EBUSY;
 152
 153         sch_tree_lock(sch);
 154
 155         drr_purge_queue(cl);
 156         qdisc_class_hash_remove(&q->clhash, &cl->common);
 157
 158         if (--cl->refcnt == 0)
 159                 drr_destroy_class(sch, cl);
 160
 161         sch_tree_unlock(sch);
 162         return 0;
 163 }
 164
 165 static unsigned long drr_get_class(struct Qdisc *sch, u32 classid)
 166 {
 167         struct drr_class *cl = drr_find_class(sch, classid);
 168
 169         if (cl != NULL)
 170                 cl->refcnt++;
 171
 172         return (unsigned long)cl;
 173 }
 174
 175 static void drr_put_class(struct Qdisc *sch, unsigned long arg)
 176 {
 177         struct drr_class *cl = (struct drr_class *)arg;
 178
 179         if (--cl->refcnt == 0)
 180                 drr_destroy_class(sch, cl);
 181 }
 182
 183 static struct tcf_proto **drr_tcf_chain(struct Qdisc *sch, unsigned long cl)
 184 {
 185         struct drr_sched *q = qdisc_priv(sch);
 186
 187         if (cl)
 188                 return NULL;
 189
 190         return &q->filter_list;
 191 }
 192
 193 static unsigned long drr_bind_tcf(struct Qdisc *sch, unsigned long parent,
 194                                   u32 classid)
 195 {
 196         struct drr_class *cl = drr_find_class(sch, classid);
 197
 198         if (cl != NULL)
 199                 cl->filter_cnt++;
 200
 201         return (unsigned long)cl;
 202 }
 203
 204 static void drr_unbind_tcf(struct Qdisc *sch, unsigned long arg)
 205 {
 206         struct drr_class *cl = (struct drr_class *)arg;
 207
 208         cl->filter_cnt--;
 209 }
 210
 211 static int drr_graft_class(struct Qdisc *sch, unsigned long arg,
 212                            struct Qdisc *new, struct Qdisc **old)
 213 {
 214         struct drr_class *cl = (struct drr_class *)arg;
 215
 216         if (new == NULL) {
 217                 new = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue,
 218                                         &pfifo_qdisc_ops, cl->common.classid);
 219                 if (new == NULL)
 220                         new = &noop_qdisc;
 221         }
 222
 223         sch_tree_lock(sch);
 224         drr_purge_queue(cl);
 225         *old = cl->qdisc;
 226         cl->qdisc = new;
 227         sch_tree_unlock(sch);
 228         return 0;
 229 }
 230
 231 static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg)
 232 {
 233         struct drr_class *cl = (struct drr_class *)arg;
 234
 235         return cl->qdisc;
 236 }
 237
 238 static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg)
 239 {
 240         struct drr_class *cl = (struct drr_class *)arg;
 241
 242         if (cl->qdisc->q.qlen == 0)
 243                 list_del(&cl->alist);
 244 }
 245
 246 static int drr_dump_class(struct Qdisc *sch, unsigned long arg,
 247                           struct sk_buff *skb, struct tcmsg *tcm)
 248 {
 249         struct drr_class *cl = (struct drr_class *)arg;
 250         struct nlattr *nest;
 251
 252         tcm->tcm_parent = TC_H_ROOT;
 253         tcm->tcm_handle = cl->common.classid;
 254         tcm->tcm_info   = cl->qdisc->handle;
 255
 256         nest = nla_nest_start(skb, TCA_OPTIONS);
 257         if (nest == NULL)
 258                 goto nla_put_failure;
 259         NLA_PUT_U32(skb, TCA_DRR_QUANTUM, cl->quantum);
 260         return nla_nest_end(skb, nest);
 261
 262 nla_put_failure:
 263         nla_nest_cancel(skb, nest);
 264         return -EMSGSIZE;
 265 }
 266
 267 static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg,
 268                                 struct gnet_dump *d)
 269 {
 270         struct drr_class *cl = (struct drr_class *)arg;
 271         struct tc_drr_stats xstats;
 272
 273         memset(&xstats, 0, sizeof(xstats));
 274         if (cl->qdisc->q.qlen)
 275                 xstats.deficit = cl->deficit;
 276
 277         if (gnet_stats_copy_basic(d, &cl->bstats) < 0 ||
 278             gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
 279             gnet_stats_copy_queue(d, &cl->qdisc->qstats) < 0)
 280                 return -1;
 281
 282         return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
 283 }
 284
 285 static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 286 {
 287         struct drr_sched *q = qdisc_priv(sch);
 288         struct drr_class *cl;
 289         struct hlist_node *n;
 290         unsigned int i;
 291
 292         if (arg->stop)
 293                 return;
 294
 295         for (i = 0; i < q->clhash.hashsize; i++) {
 296                 hlist_for_each_entry(cl, n, &q->clhash.hash[i], common.hnode) {
 297                         if (arg->count < arg->skip) {
 298                                 arg->count++;
 299                                 continue;
 300                         }
 301                         if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
 302                                 arg->stop = 1;
 303                                 return;
 304                         }
 305                         arg->count++;
 306                 }
 307         }
 308 }
 309
 310 static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch,
 311                                       int *qerr)
 312 {
 313         struct drr_sched *q = qdisc_priv(sch);
 314         struct drr_class *cl;
 315         struct tcf_result res;
 316         int result;
 317
 318         if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
 319                 cl = drr_find_class(sch, skb->priority);
 320                 if (cl != NULL)
 321                         return cl;
 322         }
 323
 324         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 325         result = tc_classify(skb, q->filter_list, &res);
 326         if (result >= 0) {
 327 #ifdef CONFIG_NET_CLS_ACT
 328                 switch (result) {
 329                 case TC_ACT_QUEUED:
 330                 case TC_ACT_STOLEN:
 331                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
 332                 case TC_ACT_SHOT:
 333                         return NULL;
 334                 }
 335 #endif
 336                 cl = (struct drr_class *)res.class;
 337                 if (cl == NULL)
 338                         cl = drr_find_class(sch, res.classid);
 339                 return cl;
 340         }
 341         return NULL;
 342 }
 343
 344 static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 345 {
 346         struct drr_sched *q = qdisc_priv(sch);
 347         struct drr_class *cl;
 348         unsigned int len;
 349         int err;
 350
 351         cl = drr_classify(skb, sch, &err);
 352         if (cl == NULL) {
 353                 if (err & __NET_XMIT_BYPASS)
 354                         sch->qstats.drops++;
 355                 kfree_skb(skb);
 356                 return err;
 357         }
 358
 359         len = qdisc_pkt_len(skb);
 360         err = qdisc_enqueue(skb, cl->qdisc);
 361         if (unlikely(err != NET_XMIT_SUCCESS)) {
 362                 if (net_xmit_drop_count(err)) {
 363                         cl->qstats.drops++;
 364                         sch->qstats.drops++;
 365                 }
 366                 return err;
 367         }
 368
 369         if (cl->qdisc->q.qlen == 1) {
 370                 list_add_tail(&cl->alist, &q->active);
 371                 cl->deficit = cl->quantum;
 372         }
 373
 374         cl->bstats.packets++;
 375         cl->bstats.bytes += len;
 376         sch->bstats.packets++;
 377         sch->bstats.bytes += len;
 378
 379         sch->q.qlen++;
 380         return err;
 381 }
 382
 383 static struct sk_buff *drr_dequeue(struct Qdisc *sch)
 384 {
 385         struct drr_sched *q = qdisc_priv(sch);
 386         struct drr_class *cl;
 387         struct sk_buff *skb;
 388         unsigned int len;
 389
 390         if (list_empty(&q->active))
 391                 goto out;
 392         while (1) {
 393                 cl = list_first_entry(&q->active, struct drr_class, alist);
 394                 skb = cl->qdisc->ops->peek(cl->qdisc);
 395                 if (skb == NULL)
 396                         goto out;
 397
 398                 len = qdisc_pkt_len(skb);
 399                 if (len <= cl->deficit) {
 400                         cl->deficit -= len;
 401                         skb = qdisc_dequeue_peeked(cl->qdisc);
 402                         if (cl->qdisc->q.qlen == 0)
 403                                 list_del(&cl->alist);
 404                         sch->q.qlen--;
 405                         return skb;
 406                 }
 407
 408                 cl->deficit += cl->quantum;
 409                 list_move_tail(&cl->alist, &q->active);
 410         }
 411 out:
 412         return NULL;
 413 }
 414
 415 static unsigned int drr_drop(struct Qdisc *sch)
 416 {
 417         struct drr_sched *q = qdisc_priv(sch);
 418         struct drr_class *cl;
 419         unsigned int len;
 420
 421         list_for_each_entry(cl, &q->active, alist) {
 422                 if (cl->qdisc->ops->drop) {
 423                         len = cl->qdisc->ops->drop(cl->qdisc);
 424                         if (len > 0) {
 425                                 sch->q.qlen--;
 426                                 if (cl->qdisc->q.qlen == 0)
 427                                         list_del(&cl->alist);
 428                                 return len;
 429                         }
 430                 }
 431         }
 432         return 0;
 433 }
 434
 435 static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
 436 {
 437         struct drr_sched *q = qdisc_priv(sch);
 438         int err;
 439
 440         err = qdisc_class_hash_init(&q->clhash);
 441         if (err < 0)
 442                 return err;
 443         INIT_LIST_HEAD(&q->active);
 444         return 0;
 445 }
 446
 447 static void drr_reset_qdisc(struct Qdisc *sch)
 448 {
 449         struct drr_sched *q = qdisc_priv(sch);
 450         struct drr_class *cl;
 451         struct hlist_node *n;
 452         unsigned int i;
 453
 454         for (i = 0; i < q->clhash.hashsize; i++) {
 455                 hlist_for_each_entry(cl, n, &q->clhash.hash[i], common.hnode) {
 456                         if (cl->qdisc->q.qlen)
 457                                 list_del(&cl->alist);
 458                         qdisc_reset(cl->qdisc);
 459                 }
 460         }
 461         sch->q.qlen = 0;
 462 }
 463
 464 static void drr_destroy_qdisc(struct Qdisc *sch)
 465 {
 466         struct drr_sched *q = qdisc_priv(sch);
 467         struct drr_class *cl;
 468         struct hlist_node *n, *next;
 469         unsigned int i;
 470
 471         tcf_destroy_chain(&q->filter_list);
 472
 473         for (i = 0; i < q->clhash.hashsize; i++) {
 474                 hlist_for_each_entry_safe(cl, n, next, &q->clhash.hash[i],
 475                                           common.hnode)
 476                         drr_destroy_class(sch, cl);
 477         }
 478         qdisc_class_hash_destroy(&q->clhash);
 479 }
 480
 481 static const struct Qdisc_class_ops drr_class_ops = {
 482         .change         = drr_change_class,
 483         .delete         = drr_delete_class,
 484         .get            = drr_get_class,
 485         .put            = drr_put_class,
 486         .tcf_chain      = drr_tcf_chain,
 487         .bind_tcf       = drr_bind_tcf,
 488         .unbind_tcf     = drr_unbind_tcf,
 489         .graft          = drr_graft_class,
 490         .leaf           = drr_class_leaf,
 491         .qlen_notify    = drr_qlen_notify,
 492         .dump           = drr_dump_class,
 493         .dump_stats     = drr_dump_class_stats,
 494         .walk           = drr_walk,
 495 };
 496
 497 static struct Qdisc_ops drr_qdisc_ops __read_mostly = {
 498         .cl_ops         = &drr_class_ops,
 499         .id             = "drr",
 500         .priv_size      = sizeof(struct drr_sched),
 501         .enqueue        = drr_enqueue,
 502         .dequeue        = drr_dequeue,
 503         .peek           = qdisc_peek_dequeued,
 504         .drop           = drr_drop,
 505         .init           = drr_init_qdisc,
 506         .reset          = drr_reset_qdisc,
 507         .destroy        = drr_destroy_qdisc,
 508         .owner          = THIS_MODULE,
 509 };
 510
 511 static int __init drr_init(void)
 512 {
 513         return register_qdisc(&drr_qdisc_ops);
 514 }
 515
 516 static void __exit drr_exit(void)
 517 {
 518         unregister_qdisc(&drr_qdisc_ops);
 519 }
 520
 521 module_init(drr_init);
 522 module_exit(drr_exit);
 523 MODULE_LICENSE("GPL");