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