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                             struct netlink_ext_ack *extack)
  69 {
  70         struct drr_sched *q = qdisc_priv(sch);
  71         struct drr_class *cl = (struct drr_class *)*arg;
  72         struct nlattr *opt = tca[TCA_OPTIONS];
  73         struct nlattr *tb[TCA_DRR_MAX + 1];
  74         u32 quantum;
  75         int err;
  76
  77         if (!opt) {
  78                 NL_SET_ERR_MSG(extack, "DRR options are required for this operation");
  79                 return -EINVAL;
  80         }
  81
  82         err = nla_parse_nested(tb, TCA_DRR_MAX, opt, drr_policy, extack);
  83         if (err < 0)
  84                 return err;
  85
  86         if (tb[TCA_DRR_QUANTUM]) {
  87                 quantum = nla_get_u32(tb[TCA_DRR_QUANTUM]);
  88                 if (quantum == 0) {
  89                         NL_SET_ERR_MSG(extack, "Specified DRR quantum cannot be zero");
  90                         return -EINVAL;
  91                 }
  92         } else
  93                 quantum = psched_mtu(qdisc_dev(sch));
  94
  95         if (cl != NULL) {
  96                 if (tca[TCA_RATE]) {
  97                         err = gen_replace_estimator(&cl->bstats, NULL,
  98                                                     &cl->rate_est,
  99                                                     NULL,
 100                                                     qdisc_root_sleeping_running(sch),
 101                                                     tca[TCA_RATE]);
 102                         if (err) {
 103                                 NL_SET_ERR_MSG(extack, "Failed to replace estimator");
 104                                 return err;
 105                         }
 106                 }
 107
 108                 sch_tree_lock(sch);
 109                 if (tb[TCA_DRR_QUANTUM])
 110                         cl->quantum = quantum;
 111                 sch_tree_unlock(sch);
 112
 113                 return 0;
 114         }
 115
 116         cl = kzalloc(sizeof(struct drr_class), GFP_KERNEL);
 117         if (cl == NULL)
 118                 return -ENOBUFS;
 119
 120         cl->common.classid = classid;
 121         cl->quantum        = quantum;
 122         cl->qdisc          = qdisc_create_dflt(sch->dev_queue,
 123                                                &pfifo_qdisc_ops, classid,
 124                                                NULL);
 125         if (cl->qdisc == NULL)
 126                 cl->qdisc = &noop_qdisc;
 127         else
 128                 qdisc_hash_add(cl->qdisc, true);
 129
 130         if (tca[TCA_RATE]) {
 131                 err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est,
 132                                             NULL,
 133                                             qdisc_root_sleeping_running(sch),
 134                                             tca[TCA_RATE]);
 135                 if (err) {
 136                         NL_SET_ERR_MSG(extack, "Failed to replace estimator");
 137                         qdisc_put(cl->qdisc);
 138                         kfree(cl);
 139                         return err;
 140                 }
 141         }
 142
 143         sch_tree_lock(sch);
 144         qdisc_class_hash_insert(&q->clhash, &cl->common);
 145         sch_tree_unlock(sch);
 146
 147         qdisc_class_hash_grow(sch, &q->clhash);
 148
 149         *arg = (unsigned long)cl;
 150         return 0;
 151 }
 152
 153 static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl)
 154 {
 155         gen_kill_estimator(&cl->rate_est);
 156         qdisc_put(cl->qdisc);
 157         kfree(cl);
 158 }
 159
 160 static int drr_delete_class(struct Qdisc *sch, unsigned long arg)
 161 {
 162         struct drr_sched *q = qdisc_priv(sch);
 163         struct drr_class *cl = (struct drr_class *)arg;
 164
 165         if (cl->filter_cnt > 0)
 166                 return -EBUSY;
 167
 168         sch_tree_lock(sch);
 169
 170         drr_purge_queue(cl);
 171         qdisc_class_hash_remove(&q->clhash, &cl->common);
 172
 173         sch_tree_unlock(sch);
 174
 175         drr_destroy_class(sch, cl);
 176         return 0;
 177 }
 178
 179 static unsigned long drr_search_class(struct Qdisc *sch, u32 classid)
 180 {
 181         return (unsigned long)drr_find_class(sch, classid);
 182 }
 183
 184 static struct tcf_block *drr_tcf_block(struct Qdisc *sch, unsigned long cl,
 185                                        struct netlink_ext_ack *extack)
 186 {
 187         struct drr_sched *q = qdisc_priv(sch);
 188
 189         if (cl) {
 190                 NL_SET_ERR_MSG(extack, "DRR classid must be zero");
 191                 return NULL;
 192         }
 193
 194         return q->block;
 195 }
 196
 197 static unsigned long drr_bind_tcf(struct Qdisc *sch, unsigned long parent,
 198                                   u32 classid)
 199 {
 200         struct drr_class *cl = drr_find_class(sch, classid);
 201
 202         if (cl != NULL)
 203                 cl->filter_cnt++;
 204
 205         return (unsigned long)cl;
 206 }
 207
 208 static void drr_unbind_tcf(struct Qdisc *sch, unsigned long arg)
 209 {
 210         struct drr_class *cl = (struct drr_class *)arg;
 211
 212         cl->filter_cnt--;
 213 }
 214
 215 static int drr_graft_class(struct Qdisc *sch, unsigned long arg,
 216                            struct Qdisc *new, struct Qdisc **old,
 217                            struct netlink_ext_ack *extack)
 218 {
 219         struct drr_class *cl = (struct drr_class *)arg;
 220
 221         if (new == NULL) {
 222                 new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
 223                                         cl->common.classid, NULL);
 224                 if (new == NULL)
 225                         new = &noop_qdisc;
 226         }
 227
 228         *old = qdisc_replace(sch, new, &cl->qdisc);
 229         return 0;
 230 }
 231
 232 static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg)
 233 {
 234         struct drr_class *cl = (struct drr_class *)arg;
 235
 236         return cl->qdisc;
 237 }
 238
 239 static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg)
 240 {
 241         struct drr_class *cl = (struct drr_class *)arg;
 242
 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         if (nla_put_u32(skb, TCA_DRR_QUANTUM, cl->quantum))
 260                 goto nla_put_failure;
 261         return nla_nest_end(skb, nest);
 262
 263 nla_put_failure:
 264         nla_nest_cancel(skb, nest);
 265         return -EMSGSIZE;
 266 }
 267
 268 static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg,
 269                                 struct gnet_dump *d)
 270 {
 271         struct drr_class *cl = (struct drr_class *)arg;
 272         __u32 qlen = cl->qdisc->q.qlen;
 273         struct tc_drr_stats xstats;
 274
 275         memset(&xstats, 0, sizeof(xstats));
 276         if (qlen)
 277                 xstats.deficit = cl->deficit;
 278
 279         if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
 280                                   d, NULL, &cl->bstats) < 0 ||
 281             gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
 282             gnet_stats_copy_queue(d, NULL, &cl->qdisc->qstats, qlen) < 0)
 283                 return -1;
 284
 285         return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
 286 }
 287
 288 static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 289 {
 290         struct drr_sched *q = qdisc_priv(sch);
 291         struct drr_class *cl;
 292         unsigned int i;
 293
 294         if (arg->stop)
 295                 return;
 296
 297         for (i = 0; i < q->clhash.hashsize; i++) {
 298                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
 299                         if (arg->count < arg->skip) {
 300                                 arg->count++;
 301                                 continue;
 302                         }
 303                         if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
 304                                 arg->stop = 1;
 305                                 return;
 306                         }
 307                         arg->count++;
 308                 }
 309         }
 310 }
 311
 312 static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch,
 313                                       int *qerr)
 314 {
 315         struct drr_sched *q = qdisc_priv(sch);
 316         struct drr_class *cl;
 317         struct tcf_result res;
 318         struct tcf_proto *fl;
 319         int result;
 320
 321         if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
 322                 cl = drr_find_class(sch, skb->priority);
 323                 if (cl != NULL)
 324                         return cl;
 325         }
 326
 327         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 328         fl = rcu_dereference_bh(q->filter_list);
 329         result = tcf_classify(skb, fl, &res, false);
 330         if (result >= 0) {
 331 #ifdef CONFIG_NET_CLS_ACT
 332                 switch (result) {
 333                 case TC_ACT_QUEUED:
 334                 case TC_ACT_STOLEN:
 335                 case TC_ACT_TRAP:
 336                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
 337                         /* fall through */
 338                 case TC_ACT_SHOT:
 339                         return NULL;
 340                 }
 341 #endif
 342                 cl = (struct drr_class *)res.class;
 343                 if (cl == NULL)
 344                         cl = drr_find_class(sch, res.classid);
 345                 return cl;
 346         }
 347         return NULL;
 348 }
 349
 350 static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 351                        struct sk_buff **to_free)
 352 {
 353         unsigned int len = qdisc_pkt_len(skb);
 354         struct drr_sched *q = qdisc_priv(sch);
 355         struct drr_class *cl;
 356         int err = 0;
 357         bool first;
 358
 359         cl = drr_classify(skb, sch, &err);
 360         if (cl == NULL) {
 361                 if (err & __NET_XMIT_BYPASS)
 362                         qdisc_qstats_drop(sch);
 363                 __qdisc_drop(skb, to_free);
 364                 return err;
 365         }
 366
 367         first = !cl->qdisc->q.qlen;
 368         err = qdisc_enqueue(skb, cl->qdisc, to_free);
 369         if (unlikely(err != NET_XMIT_SUCCESS)) {
 370                 if (net_xmit_drop_count(err)) {
 371                         cl->qstats.drops++;
 372                         qdisc_qstats_drop(sch);
 373                 }
 374                 return err;
 375         }
 376
 377         if (first) {
 378                 list_add_tail(&cl->alist, &q->active);
 379                 cl->deficit = cl->quantum;
 380         }
 381
 382         sch->qstats.backlog += len;
 383         sch->q.qlen++;
 384         return err;
 385 }
 386
 387 static struct sk_buff *drr_dequeue(struct Qdisc *sch)
 388 {
 389         struct drr_sched *q = qdisc_priv(sch);
 390         struct drr_class *cl;
 391         struct sk_buff *skb;
 392         unsigned int len;
 393
 394         if (list_empty(&q->active))
 395                 goto out;
 396         while (1) {
 397                 cl = list_first_entry(&q->active, struct drr_class, alist);
 398                 skb = cl->qdisc->ops->peek(cl->qdisc);
 399                 if (skb == NULL) {
 400                         qdisc_warn_nonwc(__func__, cl->qdisc);
 401                         goto out;
 402                 }
 403
 404                 len = qdisc_pkt_len(skb);
 405                 if (len <= cl->deficit) {
 406                         cl->deficit -= len;
 407                         skb = qdisc_dequeue_peeked(cl->qdisc);
 408                         if (unlikely(skb == NULL))
 409                                 goto out;
 410                         if (cl->qdisc->q.qlen == 0)
 411                                 list_del(&cl->alist);
 412
 413                         bstats_update(&cl->bstats, skb);
 414                         qdisc_bstats_update(sch, skb);
 415                         qdisc_qstats_backlog_dec(sch, skb);
 416                         sch->q.qlen--;
 417                         return skb;
 418                 }
 419
 420                 cl->deficit += cl->quantum;
 421                 list_move_tail(&cl->alist, &q->active);
 422         }
 423 out:
 424         return NULL;
 425 }
 426
 427 static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt,
 428                           struct netlink_ext_ack *extack)
 429 {
 430         struct drr_sched *q = qdisc_priv(sch);
 431         int err;
 432
 433         err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
 434         if (err)
 435                 return err;
 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         unsigned int i;
 448
 449         for (i = 0; i < q->clhash.hashsize; i++) {
 450                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
 451                         if (cl->qdisc->q.qlen)
 452                                 list_del(&cl->alist);
 453                         qdisc_reset(cl->qdisc);
 454                 }
 455         }
 456         sch->qstats.backlog = 0;
 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 *next;
 465         unsigned int i;
 466
 467         tcf_block_put(q->block);
 468
 469         for (i = 0; i < q->clhash.hashsize; i++) {
 470                 hlist_for_each_entry_safe(cl, 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         .find           = drr_search_class,
 481         .tcf_block      = drr_tcf_block,
 482         .bind_tcf       = drr_bind_tcf,
 483         .unbind_tcf     = drr_unbind_tcf,
 484         .graft          = drr_graft_class,
 485         .leaf           = drr_class_leaf,
 486         .qlen_notify    = drr_qlen_notify,
 487         .dump           = drr_dump_class,
 488         .dump_stats     = drr_dump_class_stats,
 489         .walk           = drr_walk,
 490 };
 491
 492 static struct Qdisc_ops drr_qdisc_ops __read_mostly = {
 493         .cl_ops         = &drr_class_ops,
 494         .id             = "drr",
 495         .priv_size      = sizeof(struct drr_sched),
 496         .enqueue        = drr_enqueue,
 497         .dequeue        = drr_dequeue,
 498         .peek           = qdisc_peek_dequeued,
 499         .init           = drr_init_qdisc,
 500         .reset          = drr_reset_qdisc,
 501         .destroy        = drr_destroy_qdisc,
 502         .owner          = THIS_MODULE,
 503 };
 504
 505 static int __init drr_init(void)
 506 {
 507         return register_qdisc(&drr_qdisc_ops);
 508 }
 509
 510 static void __exit drr_exit(void)
 511 {
 512         unregister_qdisc(&drr_qdisc_ops);
 513 }
 514
 515 module_init(drr_init);
 516 module_exit(drr_exit);
 517 MODULE_LICENSE("GPL");