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