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 refcnt; 24 unsigned int filter_cnt; 25 26 struct gnet_stats_basic_packed bstats; 27 struct gnet_stats_queue qstats; 28 struct net_rate_estimator __rcu *rate_est; 29 struct list_head alist; 30 struct Qdisc *qdisc; 31 32 u32 quantum; 33 u32 deficit; 34 }; 35 36 struct drr_sched { 37 struct list_head active; 38 struct tcf_proto __rcu *filter_list; 39 struct tcf_block *block; 40 struct Qdisc_class_hash clhash; 41 }; 42 43 static struct drr_class *drr_find_class(struct Qdisc *sch, u32 classid) 44 { 45 struct drr_sched *q = qdisc_priv(sch); 46 struct Qdisc_class_common *clc; 47 48 clc = qdisc_class_find(&q->clhash, classid); 49 if (clc == NULL) 50 return NULL; 51 return container_of(clc, struct drr_class, common); 52 } 53 54 static void drr_purge_queue(struct drr_class *cl) 55 { 56 unsigned int len = cl->qdisc->q.qlen; 57 unsigned int backlog = cl->qdisc->qstats.backlog; 58 59 qdisc_reset(cl->qdisc); 60 qdisc_tree_reduce_backlog(cl->qdisc, len, backlog); 61 } 62 63 static const struct nla_policy drr_policy[TCA_DRR_MAX + 1] = { 64 [TCA_DRR_QUANTUM] = { .type = NLA_U32 }, 65 }; 66 67 static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 68 struct nlattr **tca, unsigned long *arg) 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 return -EINVAL; 79 80 err = nla_parse_nested(tb, TCA_DRR_MAX, opt, drr_policy, NULL); 81 if (err < 0) 82 return err; 83 84 if (tb[TCA_DRR_QUANTUM]) { 85 quantum = nla_get_u32(tb[TCA_DRR_QUANTUM]); 86 if (quantum == 0) 87 return -EINVAL; 88 } else 89 quantum = psched_mtu(qdisc_dev(sch)); 90 91 if (cl != NULL) { 92 if (tca[TCA_RATE]) { 93 err = gen_replace_estimator(&cl->bstats, NULL, 94 &cl->rate_est, 95 NULL, 96 qdisc_root_sleeping_running(sch), 97 tca[TCA_RATE]); 98 if (err) 99 return err; 100 } 101 102 sch_tree_lock(sch); 103 if (tb[TCA_DRR_QUANTUM]) 104 cl->quantum = quantum; 105 sch_tree_unlock(sch); 106 107 return 0; 108 } 109 110 cl = kzalloc(sizeof(struct drr_class), GFP_KERNEL); 111 if (cl == NULL) 112 return -ENOBUFS; 113 114 cl->refcnt = 1; 115 cl->common.classid = classid; 116 cl->quantum = quantum; 117 cl->qdisc = qdisc_create_dflt(sch->dev_queue, 118 &pfifo_qdisc_ops, classid); 119 if (cl->qdisc == NULL) 120 cl->qdisc = &noop_qdisc; 121 else 122 qdisc_hash_add(cl->qdisc, true); 123 124 if (tca[TCA_RATE]) { 125 err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est, 126 NULL, 127 qdisc_root_sleeping_running(sch), 128 tca[TCA_RATE]); 129 if (err) { 130 qdisc_destroy(cl->qdisc); 131 kfree(cl); 132 return err; 133 } 134 } 135 136 sch_tree_lock(sch); 137 qdisc_class_hash_insert(&q->clhash, &cl->common); 138 sch_tree_unlock(sch); 139 140 qdisc_class_hash_grow(sch, &q->clhash); 141 142 *arg = (unsigned long)cl; 143 return 0; 144 } 145 146 static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl) 147 { 148 gen_kill_estimator(&cl->rate_est); 149 qdisc_destroy(cl->qdisc); 150 kfree(cl); 151 } 152 153 static int drr_delete_class(struct Qdisc *sch, unsigned long arg) 154 { 155 struct drr_sched *q = qdisc_priv(sch); 156 struct drr_class *cl = (struct drr_class *)arg; 157 158 if (cl->filter_cnt > 0) 159 return -EBUSY; 160 161 sch_tree_lock(sch); 162 163 drr_purge_queue(cl); 164 qdisc_class_hash_remove(&q->clhash, &cl->common); 165 166 BUG_ON(--cl->refcnt == 0); 167 /* 168 * This shouldn't happen: we "hold" one cops->get() when called 169 * from tc_ctl_tclass; the destroy method is done from cops->put(). 170 */ 171 172 sch_tree_unlock(sch); 173 return 0; 174 } 175 176 static unsigned long drr_get_class(struct Qdisc *sch, u32 classid) 177 { 178 struct drr_class *cl = drr_find_class(sch, classid); 179 180 if (cl != NULL) 181 cl->refcnt++; 182 183 return (unsigned long)cl; 184 } 185 186 static void drr_put_class(struct Qdisc *sch, unsigned long arg) 187 { 188 struct drr_class *cl = (struct drr_class *)arg; 189 190 if (--cl->refcnt == 0) 191 drr_destroy_class(sch, cl); 192 } 193 194 static struct tcf_block *drr_tcf_block(struct Qdisc *sch, unsigned long cl) 195 { 196 struct drr_sched *q = qdisc_priv(sch); 197 198 if (cl) 199 return NULL; 200 201 return q->block; 202 } 203 204 static unsigned long drr_bind_tcf(struct Qdisc *sch, unsigned long parent, 205 u32 classid) 206 { 207 struct drr_class *cl = drr_find_class(sch, classid); 208 209 if (cl != NULL) 210 cl->filter_cnt++; 211 212 return (unsigned long)cl; 213 } 214 215 static void drr_unbind_tcf(struct Qdisc *sch, unsigned long arg) 216 { 217 struct drr_class *cl = (struct drr_class *)arg; 218 219 cl->filter_cnt--; 220 } 221 222 static int drr_graft_class(struct Qdisc *sch, unsigned long arg, 223 struct Qdisc *new, struct Qdisc **old) 224 { 225 struct drr_class *cl = (struct drr_class *)arg; 226 227 if (new == NULL) { 228 new = qdisc_create_dflt(sch->dev_queue, 229 &pfifo_qdisc_ops, cl->common.classid); 230 if (new == NULL) 231 new = &noop_qdisc; 232 } 233 234 *old = qdisc_replace(sch, new, &cl->qdisc); 235 return 0; 236 } 237 238 static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg) 239 { 240 struct drr_class *cl = (struct drr_class *)arg; 241 242 return cl->qdisc; 243 } 244 245 static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg) 246 { 247 struct drr_class *cl = (struct drr_class *)arg; 248 249 if (cl->qdisc->q.qlen == 0) 250 list_del(&cl->alist); 251 } 252 253 static int drr_dump_class(struct Qdisc *sch, unsigned long arg, 254 struct sk_buff *skb, struct tcmsg *tcm) 255 { 256 struct drr_class *cl = (struct drr_class *)arg; 257 struct nlattr *nest; 258 259 tcm->tcm_parent = TC_H_ROOT; 260 tcm->tcm_handle = cl->common.classid; 261 tcm->tcm_info = cl->qdisc->handle; 262 263 nest = nla_nest_start(skb, TCA_OPTIONS); 264 if (nest == NULL) 265 goto nla_put_failure; 266 if (nla_put_u32(skb, TCA_DRR_QUANTUM, cl->quantum)) 267 goto nla_put_failure; 268 return nla_nest_end(skb, nest); 269 270 nla_put_failure: 271 nla_nest_cancel(skb, nest); 272 return -EMSGSIZE; 273 } 274 275 static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg, 276 struct gnet_dump *d) 277 { 278 struct drr_class *cl = (struct drr_class *)arg; 279 __u32 qlen = cl->qdisc->q.qlen; 280 struct tc_drr_stats xstats; 281 282 memset(&xstats, 0, sizeof(xstats)); 283 if (qlen) 284 xstats.deficit = cl->deficit; 285 286 if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), 287 d, NULL, &cl->bstats) < 0 || 288 gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 || 289 gnet_stats_copy_queue(d, NULL, &cl->qdisc->qstats, qlen) < 0) 290 return -1; 291 292 return gnet_stats_copy_app(d, &xstats, sizeof(xstats)); 293 } 294 295 static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg) 296 { 297 struct drr_sched *q = qdisc_priv(sch); 298 struct drr_class *cl; 299 unsigned int i; 300 301 if (arg->stop) 302 return; 303 304 for (i = 0; i < q->clhash.hashsize; i++) { 305 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { 306 if (arg->count < arg->skip) { 307 arg->count++; 308 continue; 309 } 310 if (arg->fn(sch, (unsigned long)cl, arg) < 0) { 311 arg->stop = 1; 312 return; 313 } 314 arg->count++; 315 } 316 } 317 } 318 319 static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch, 320 int *qerr) 321 { 322 struct drr_sched *q = qdisc_priv(sch); 323 struct drr_class *cl; 324 struct tcf_result res; 325 struct tcf_proto *fl; 326 int result; 327 328 if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) { 329 cl = drr_find_class(sch, skb->priority); 330 if (cl != NULL) 331 return cl; 332 } 333 334 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; 335 fl = rcu_dereference_bh(q->filter_list); 336 result = tcf_classify(skb, fl, &res, false); 337 if (result >= 0) { 338 #ifdef CONFIG_NET_CLS_ACT 339 switch (result) { 340 case TC_ACT_QUEUED: 341 case TC_ACT_STOLEN: 342 case TC_ACT_TRAP: 343 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN; 344 case TC_ACT_SHOT: 345 return NULL; 346 } 347 #endif 348 cl = (struct drr_class *)res.class; 349 if (cl == NULL) 350 cl = drr_find_class(sch, res.classid); 351 return cl; 352 } 353 return NULL; 354 } 355 356 static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch, 357 struct sk_buff **to_free) 358 { 359 struct drr_sched *q = qdisc_priv(sch); 360 struct drr_class *cl; 361 int err = 0; 362 363 cl = drr_classify(skb, sch, &err); 364 if (cl == NULL) { 365 if (err & __NET_XMIT_BYPASS) 366 qdisc_qstats_drop(sch); 367 __qdisc_drop(skb, to_free); 368 return err; 369 } 370 371 err = qdisc_enqueue(skb, cl->qdisc, to_free); 372 if (unlikely(err != NET_XMIT_SUCCESS)) { 373 if (net_xmit_drop_count(err)) { 374 cl->qstats.drops++; 375 qdisc_qstats_drop(sch); 376 } 377 return err; 378 } 379 380 if (cl->qdisc->q.qlen == 1) { 381 list_add_tail(&cl->alist, &q->active); 382 cl->deficit = cl->quantum; 383 } 384 385 qdisc_qstats_backlog_inc(sch, skb); 386 sch->q.qlen++; 387 return err; 388 } 389 390 static struct sk_buff *drr_dequeue(struct Qdisc *sch) 391 { 392 struct drr_sched *q = qdisc_priv(sch); 393 struct drr_class *cl; 394 struct sk_buff *skb; 395 unsigned int len; 396 397 if (list_empty(&q->active)) 398 goto out; 399 while (1) { 400 cl = list_first_entry(&q->active, struct drr_class, alist); 401 skb = cl->qdisc->ops->peek(cl->qdisc); 402 if (skb == NULL) { 403 qdisc_warn_nonwc(__func__, cl->qdisc); 404 goto out; 405 } 406 407 len = qdisc_pkt_len(skb); 408 if (len <= cl->deficit) { 409 cl->deficit -= len; 410 skb = qdisc_dequeue_peeked(cl->qdisc); 411 if (unlikely(skb == NULL)) 412 goto out; 413 if (cl->qdisc->q.qlen == 0) 414 list_del(&cl->alist); 415 416 bstats_update(&cl->bstats, skb); 417 qdisc_bstats_update(sch, skb); 418 qdisc_qstats_backlog_dec(sch, skb); 419 sch->q.qlen--; 420 return skb; 421 } 422 423 cl->deficit += cl->quantum; 424 list_move_tail(&cl->alist, &q->active); 425 } 426 out: 427 return NULL; 428 } 429 430 static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt) 431 { 432 struct drr_sched *q = qdisc_priv(sch); 433 int err; 434 435 err = tcf_block_get(&q->block, &q->filter_list); 436 if (err) 437 return err; 438 err = qdisc_class_hash_init(&q->clhash); 439 if (err < 0) 440 return err; 441 INIT_LIST_HEAD(&q->active); 442 return 0; 443 } 444 445 static void drr_reset_qdisc(struct Qdisc *sch) 446 { 447 struct drr_sched *q = qdisc_priv(sch); 448 struct drr_class *cl; 449 unsigned int i; 450 451 for (i = 0; i < q->clhash.hashsize; i++) { 452 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { 453 if (cl->qdisc->q.qlen) 454 list_del(&cl->alist); 455 qdisc_reset(cl->qdisc); 456 } 457 } 458 sch->qstats.backlog = 0; 459 sch->q.qlen = 0; 460 } 461 462 static void drr_destroy_qdisc(struct Qdisc *sch) 463 { 464 struct drr_sched *q = qdisc_priv(sch); 465 struct drr_class *cl; 466 struct hlist_node *next; 467 unsigned int i; 468 469 tcf_block_put(q->block); 470 471 for (i = 0; i < q->clhash.hashsize; i++) { 472 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i], 473 common.hnode) 474 drr_destroy_class(sch, cl); 475 } 476 qdisc_class_hash_destroy(&q->clhash); 477 } 478 479 static const struct Qdisc_class_ops drr_class_ops = { 480 .change = drr_change_class, 481 .delete = drr_delete_class, 482 .get = drr_get_class, 483 .put = drr_put_class, 484 .tcf_block = drr_tcf_block, 485 .bind_tcf = drr_bind_tcf, 486 .unbind_tcf = drr_unbind_tcf, 487 .graft = drr_graft_class, 488 .leaf = drr_class_leaf, 489 .qlen_notify = drr_qlen_notify, 490 .dump = drr_dump_class, 491 .dump_stats = drr_dump_class_stats, 492 .walk = drr_walk, 493 }; 494 495 static struct Qdisc_ops drr_qdisc_ops __read_mostly = { 496 .cl_ops = &drr_class_ops, 497 .id = "drr", 498 .priv_size = sizeof(struct drr_sched), 499 .enqueue = drr_enqueue, 500 .dequeue = drr_dequeue, 501 .peek = qdisc_peek_dequeued, 502 .init = drr_init_qdisc, 503 .reset = drr_reset_qdisc, 504 .destroy = drr_destroy_qdisc, 505 .owner = THIS_MODULE, 506 }; 507 508 static int __init drr_init(void) 509 { 510 return register_qdisc(&drr_qdisc_ops); 511 } 512 513 static void __exit drr_exit(void) 514 { 515 unregister_qdisc(&drr_qdisc_ops); 516 } 517 518 module_init(drr_init); 519 module_exit(drr_exit); 520 MODULE_LICENSE("GPL"); 521