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/slab.h>
  13 #include <linux/init.h>
  14 #include <linux/errno.h>
  15 #include <linux/netdevice.h>
  16 #include <linux/pkt_sched.h>
  17 #include <net/sch_generic.h>
  18 #include <net/pkt_sched.h>
  19 #include <net/pkt_cls.h>
  20
  21 struct drr_class {
  22         struct Qdisc_class_common       common;
  23         unsigned int                    filter_cnt;
  24
  25         struct gnet_stats_basic_packed          bstats;
  26         struct gnet_stats_queue         qstats;
  27         struct net_rate_estimator __rcu *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 __rcu          *filter_list;
  38         struct tcf_block                *block;
  39         struct Qdisc_class_hash         clhash;
  40 };
  41
  42 static struct drr_class *drr_find_class(struct Qdisc *sch, u32 classid)
  43 {
  44         struct drr_sched *q = qdisc_priv(sch);
  45         struct Qdisc_class_common *clc;
  46
  47         clc = qdisc_class_find(&q->clhash, classid);
  48         if (clc == NULL)
  49                 return NULL;
  50         return container_of(clc, struct drr_class, common);
  51 }
  52
  53 static void drr_purge_queue(struct drr_class *cl)
  54 {
  55         unsigned int len = cl->qdisc->q.qlen;
  56         unsigned int backlog = cl->qdisc->qstats.backlog;
  57
  58         qdisc_reset(cl->qdisc);
  59         qdisc_tree_reduce_backlog(cl->qdisc, len, backlog);
  60 }
  61
  62 static const struct nla_policy drr_policy[TCA_DRR_MAX + 1] = {
  63         [TCA_DRR_QUANTUM]       = { .type = NLA_U32 },
  64 };
  65
  66 static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
  67                             struct nlattr **tca, unsigned long *arg)
  68 {
  69         struct drr_sched *q = qdisc_priv(sch);
  70         struct drr_class *cl = (struct drr_class *)*arg;
  71         struct nlattr *opt = tca[TCA_OPTIONS];
  72         struct nlattr *tb[TCA_DRR_MAX + 1];
  73         u32 quantum;
  74         int err;
  75
  76         if (!opt)
  77                 return -EINVAL;
  78
  79         err = nla_parse_nested(tb, TCA_DRR_MAX, opt, drr_policy, NULL);
  80         if (err < 0)
  81                 return err;
  82
  83         if (tb[TCA_DRR_QUANTUM]) {
  84                 quantum = nla_get_u32(tb[TCA_DRR_QUANTUM]);
  85                 if (quantum == 0)
  86                         return -EINVAL;
  87         } else
  88                 quantum = psched_mtu(qdisc_dev(sch));
  89
  90         if (cl != NULL) {
  91                 if (tca[TCA_RATE]) {
  92                         err = gen_replace_estimator(&cl->bstats, NULL,
  93                                                     &cl->rate_est,
  94                                                     NULL,
  95                                                     qdisc_root_sleeping_running(sch),
  96                                                     tca[TCA_RATE]);
  97                         if (err)
  98                                 return err;
  99                 }
 100
 101                 sch_tree_lock(sch);
 102                 if (tb[TCA_DRR_QUANTUM])
 103                         cl->quantum = quantum;
 104                 sch_tree_unlock(sch);
 105
 106                 return 0;
 107         }
 108
 109         cl = kzalloc(sizeof(struct drr_class), GFP_KERNEL);
 110         if (cl == NULL)
 111                 return -ENOBUFS;
 112
 113         cl->common.classid = classid;
 114         cl->quantum        = quantum;
 115         cl->qdisc          = qdisc_create_dflt(sch->dev_queue,
 116                                                &pfifo_qdisc_ops, classid);
 117         if (cl->qdisc == NULL)
 118                 cl->qdisc = &noop_qdisc;
 119         else
 120                 qdisc_hash_add(cl->qdisc, true);
 121
 122         if (tca[TCA_RATE]) {
 123                 err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est,
 124                                             NULL,
 125                                             qdisc_root_sleeping_running(sch),
 126                                             tca[TCA_RATE]);
 127                 if (err) {
 128                         qdisc_destroy(cl->qdisc);
 129                         kfree(cl);
 130                         return err;
 131                 }
 132         }
 133
 134         sch_tree_lock(sch);
 135         qdisc_class_hash_insert(&q->clhash, &cl->common);
 136         sch_tree_unlock(sch);
 137
 138         qdisc_class_hash_grow(sch, &q->clhash);
 139
 140         *arg = (unsigned long)cl;
 141         return 0;
 142 }
 143
 144 static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl)
 145 {
 146         gen_kill_estimator(&cl->rate_est);
 147         qdisc_destroy(cl->qdisc);
 148         kfree(cl);
 149 }
 150
 151 static int drr_delete_class(struct Qdisc *sch, unsigned long arg)
 152 {
 153         struct drr_sched *q = qdisc_priv(sch);
 154         struct drr_class *cl = (struct drr_class *)arg;
 155
 156         if (cl->filter_cnt > 0)
 157                 return -EBUSY;
 158
 159         sch_tree_lock(sch);
 160
 161         drr_purge_queue(cl);
 162         qdisc_class_hash_remove(&q->clhash, &cl->common);
 163
 164         sch_tree_unlock(sch);
 165
 166         drr_destroy_class(sch, cl);
 167         return 0;
 168 }
 169
 170 static unsigned long drr_search_class(struct Qdisc *sch, u32 classid)
 171 {
 172         return (unsigned long)drr_find_class(sch, classid);
 173 }
 174
 175 static struct tcf_block *drr_tcf_block(struct Qdisc *sch, unsigned long cl)
 176 {
 177         struct drr_sched *q = qdisc_priv(sch);
 178
 179         if (cl)
 180                 return NULL;
 181
 182         return q->block;
 183 }
 184
 185 static unsigned long drr_bind_tcf(struct Qdisc *sch, unsigned long parent,
 186                                   u32 classid)
 187 {
 188         struct drr_class *cl = drr_find_class(sch, classid);
 189
 190         if (cl != NULL)
 191                 cl->filter_cnt++;
 192
 193         return (unsigned long)cl;
 194 }
 195
 196 static void drr_unbind_tcf(struct Qdisc *sch, unsigned long arg)
 197 {
 198         struct drr_class *cl = (struct drr_class *)arg;
 199
 200         cl->filter_cnt--;
 201 }
 202
 203 static int drr_graft_class(struct Qdisc *sch, unsigned long arg,
 204                            struct Qdisc *new, struct Qdisc **old)
 205 {
 206         struct drr_class *cl = (struct drr_class *)arg;
 207
 208         if (new == NULL) {
 209                 new = qdisc_create_dflt(sch->dev_queue,
 210                                         &pfifo_qdisc_ops, cl->common.classid);
 211                 if (new == NULL)
 212                         new = &noop_qdisc;
 213         }
 214
 215         *old = qdisc_replace(sch, new, &cl->qdisc);
 216         return 0;
 217 }
 218
 219 static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg)
 220 {
 221         struct drr_class *cl = (struct drr_class *)arg;
 222
 223         return cl->qdisc;
 224 }
 225
 226 static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg)
 227 {
 228         struct drr_class *cl = (struct drr_class *)arg;
 229
 230         list_del(&cl->alist);
 231 }
 232
 233 static int drr_dump_class(struct Qdisc *sch, unsigned long arg,
 234                           struct sk_buff *skb, struct tcmsg *tcm)
 235 {
 236         struct drr_class *cl = (struct drr_class *)arg;
 237         struct nlattr *nest;
 238
 239         tcm->tcm_parent = TC_H_ROOT;
 240         tcm->tcm_handle = cl->common.classid;
 241         tcm->tcm_info   = cl->qdisc->handle;
 242
 243         nest = nla_nest_start(skb, TCA_OPTIONS);
 244         if (nest == NULL)
 245                 goto nla_put_failure;
 246         if (nla_put_u32(skb, TCA_DRR_QUANTUM, cl->quantum))
 247                 goto nla_put_failure;
 248         return nla_nest_end(skb, nest);
 249
 250 nla_put_failure:
 251         nla_nest_cancel(skb, nest);
 252         return -EMSGSIZE;
 253 }
 254
 255 static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg,
 256                                 struct gnet_dump *d)
 257 {
 258         struct drr_class *cl = (struct drr_class *)arg;
 259         __u32 qlen = cl->qdisc->q.qlen;
 260         struct tc_drr_stats xstats;
 261
 262         memset(&xstats, 0, sizeof(xstats));
 263         if (qlen)
 264                 xstats.deficit = cl->deficit;
 265
 266         if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
 267                                   d, NULL, &cl->bstats) < 0 ||
 268             gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
 269             gnet_stats_copy_queue(d, NULL, &cl->qdisc->qstats, qlen) < 0)
 270                 return -1;
 271
 272         return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
 273 }
 274
 275 static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 276 {
 277         struct drr_sched *q = qdisc_priv(sch);
 278         struct drr_class *cl;
 279         unsigned int i;
 280
 281         if (arg->stop)
 282                 return;
 283
 284         for (i = 0; i < q->clhash.hashsize; i++) {
 285                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
 286                         if (arg->count < arg->skip) {
 287                                 arg->count++;
 288                                 continue;
 289                         }
 290                         if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
 291                                 arg->stop = 1;
 292                                 return;
 293                         }
 294                         arg->count++;
 295                 }
 296         }
 297 }
 298
 299 static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch,
 300                                       int *qerr)
 301 {
 302         struct drr_sched *q = qdisc_priv(sch);
 303         struct drr_class *cl;
 304         struct tcf_result res;
 305         struct tcf_proto *fl;
 306         int result;
 307
 308         if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
 309                 cl = drr_find_class(sch, skb->priority);
 310                 if (cl != NULL)
 311                         return cl;
 312         }
 313
 314         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 315         fl = rcu_dereference_bh(q->filter_list);
 316         result = tcf_classify(skb, fl, &res, false);
 317         if (result >= 0) {
 318 #ifdef CONFIG_NET_CLS_ACT
 319                 switch (result) {
 320                 case TC_ACT_QUEUED:
 321                 case TC_ACT_STOLEN:
 322                 case TC_ACT_TRAP:
 323                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
 324                 case TC_ACT_SHOT:
 325                         return NULL;
 326                 }
 327 #endif
 328                 cl = (struct drr_class *)res.class;
 329                 if (cl == NULL)
 330                         cl = drr_find_class(sch, res.classid);
 331                 return cl;
 332         }
 333         return NULL;
 334 }
 335
 336 static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 337                        struct sk_buff **to_free)
 338 {
 339         struct drr_sched *q = qdisc_priv(sch);
 340         struct drr_class *cl;
 341         int err = 0;
 342
 343         cl = drr_classify(skb, sch, &err);
 344         if (cl == NULL) {
 345                 if (err & __NET_XMIT_BYPASS)
 346                         qdisc_qstats_drop(sch);
 347                 __qdisc_drop(skb, to_free);
 348                 return err;
 349         }
 350
 351         err = qdisc_enqueue(skb, cl->qdisc, to_free);
 352         if (unlikely(err != NET_XMIT_SUCCESS)) {
 353                 if (net_xmit_drop_count(err)) {
 354                         cl->qstats.drops++;
 355                         qdisc_qstats_drop(sch);
 356                 }
 357                 return err;
 358         }
 359
 360         if (cl->qdisc->q.qlen == 1) {
 361                 list_add_tail(&cl->alist, &q->active);
 362                 cl->deficit = cl->quantum;
 363         }
 364
 365         qdisc_qstats_backlog_inc(sch, skb);
 366         sch->q.qlen++;
 367         return err;
 368 }
 369
 370 static struct sk_buff *drr_dequeue(struct Qdisc *sch)
 371 {
 372         struct drr_sched *q = qdisc_priv(sch);
 373         struct drr_class *cl;
 374         struct sk_buff *skb;
 375         unsigned int len;
 376
 377         if (list_empty(&q->active))
 378                 goto out;
 379         while (1) {
 380                 cl = list_first_entry(&q->active, struct drr_class, alist);
 381                 skb = cl->qdisc->ops->peek(cl->qdisc);
 382                 if (skb == NULL) {
 383                         qdisc_warn_nonwc(__func__, cl->qdisc);
 384                         goto out;
 385                 }
 386
 387                 len = qdisc_pkt_len(skb);
 388                 if (len <= cl->deficit) {
 389                         cl->deficit -= len;
 390                         skb = qdisc_dequeue_peeked(cl->qdisc);
 391                         if (unlikely(skb == NULL))
 392                                 goto out;
 393                         if (cl->qdisc->q.qlen == 0)
 394                                 list_del(&cl->alist);
 395
 396                         bstats_update(&cl->bstats, skb);
 397                         qdisc_bstats_update(sch, skb);
 398                         qdisc_qstats_backlog_dec(sch, skb);
 399                         sch->q.qlen--;
 400                         return skb;
 401                 }
 402
 403                 cl->deficit += cl->quantum;
 404                 list_move_tail(&cl->alist, &q->active);
 405         }
 406 out:
 407         return NULL;
 408 }
 409
 410 static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
 411 {
 412         struct drr_sched *q = qdisc_priv(sch);
 413         int err;
 414
 415         err = tcf_block_get(&q->block, &q->filter_list);
 416         if (err)
 417                 return err;
 418         err = qdisc_class_hash_init(&q->clhash);
 419         if (err < 0)
 420                 return err;
 421         INIT_LIST_HEAD(&q->active);
 422         return 0;
 423 }
 424
 425 static void drr_reset_qdisc(struct Qdisc *sch)
 426 {
 427         struct drr_sched *q = qdisc_priv(sch);
 428         struct drr_class *cl;
 429         unsigned int i;
 430
 431         for (i = 0; i < q->clhash.hashsize; i++) {
 432                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
 433                         if (cl->qdisc->q.qlen)
 434                                 list_del(&cl->alist);
 435                         qdisc_reset(cl->qdisc);
 436                 }
 437         }
 438         sch->qstats.backlog = 0;
 439         sch->q.qlen = 0;
 440 }
 441
 442 static void drr_destroy_qdisc(struct Qdisc *sch)
 443 {
 444         struct drr_sched *q = qdisc_priv(sch);
 445         struct drr_class *cl;
 446         struct hlist_node *next;
 447         unsigned int i;
 448
 449         tcf_block_put(q->block);
 450
 451         for (i = 0; i < q->clhash.hashsize; i++) {
 452                 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],
 453                                           common.hnode)
 454                         drr_destroy_class(sch, cl);
 455         }
 456         qdisc_class_hash_destroy(&q->clhash);
 457 }
 458
 459 static const struct Qdisc_class_ops drr_class_ops = {
 460         .change         = drr_change_class,
 461         .delete         = drr_delete_class,
 462         .find           = drr_search_class,
 463         .tcf_block      = drr_tcf_block,
 464         .bind_tcf       = drr_bind_tcf,
 465         .unbind_tcf     = drr_unbind_tcf,
 466         .graft          = drr_graft_class,
 467         .leaf           = drr_class_leaf,
 468         .qlen_notify    = drr_qlen_notify,
 469         .dump           = drr_dump_class,
 470         .dump_stats     = drr_dump_class_stats,
 471         .walk           = drr_walk,
 472 };
 473
 474 static struct Qdisc_ops drr_qdisc_ops __read_mostly = {
 475         .cl_ops         = &drr_class_ops,
 476         .id             = "drr",
 477         .priv_size      = sizeof(struct drr_sched),
 478         .enqueue        = drr_enqueue,
 479         .dequeue        = drr_dequeue,
 480         .peek           = qdisc_peek_dequeued,
 481         .init           = drr_init_qdisc,
 482         .reset          = drr_reset_qdisc,
 483         .destroy        = drr_destroy_qdisc,
 484         .owner          = THIS_MODULE,
 485 };
 486
 487 static int __init drr_init(void)
 488 {
 489         return register_qdisc(&drr_qdisc_ops);
 490 }
 491
 492 static void __exit drr_exit(void)
 493 {
 494         unregister_qdisc(&drr_qdisc_ops);
 495 }
 496
 497 module_init(drr_init);
 498 module_exit(drr_exit);
 499 MODULE_LICENSE("GPL");