1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * net/sched/sch_drr.c Deficit Round Robin scheduler 4 * 5 * Copyright (c) 2008 Patrick McHardy <kaber@trash.net> 6 */ 7 8 #include <linux/module.h> 9 #include <linux/slab.h> 10 #include <linux/init.h> 11 #include <linux/errno.h> 12 #include <linux/netdevice.h> 13 #include <linux/pkt_sched.h> 14 #include <net/sch_generic.h> 15 #include <net/pkt_sched.h> 16 #include <net/pkt_cls.h> 17 18 struct drr_class { 19 struct Qdisc_class_common common; 20 unsigned int filter_cnt; 21 22 struct gnet_stats_basic_packed bstats; 23 struct gnet_stats_queue qstats; 24 struct net_rate_estimator __rcu *rate_est; 25 struct list_head alist; 26 struct Qdisc *qdisc; 27 28 u32 quantum; 29 u32 deficit; 30 }; 31 32 struct drr_sched { 33 struct list_head active; 34 struct tcf_proto __rcu *filter_list; 35 struct tcf_block *block; 36 struct Qdisc_class_hash clhash; 37 }; 38 39 static struct drr_class *drr_find_class(struct Qdisc *sch, u32 classid) 40 { 41 struct drr_sched *q = qdisc_priv(sch); 42 struct Qdisc_class_common *clc; 43 44 clc = qdisc_class_find(&q->clhash, classid); 45 if (clc == NULL) 46 return NULL; 47 return container_of(clc, struct drr_class, common); 48 } 49 50 static const struct nla_policy drr_policy[TCA_DRR_MAX + 1] = { 51 [TCA_DRR_QUANTUM] = { .type = NLA_U32 }, 52 }; 53 54 static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 55 struct nlattr **tca, unsigned long *arg, 56 struct netlink_ext_ack *extack) 57 { 58 struct drr_sched *q = qdisc_priv(sch); 59 struct drr_class *cl = (struct drr_class *)*arg; 60 struct nlattr *opt = tca[TCA_OPTIONS]; 61 struct nlattr *tb[TCA_DRR_MAX + 1]; 62 u32 quantum; 63 int err; 64 65 if (!opt) { 66 NL_SET_ERR_MSG(extack, "DRR options are required for this operation"); 67 return -EINVAL; 68 } 69 70 err = nla_parse_nested_deprecated(tb, TCA_DRR_MAX, opt, drr_policy, 71 extack); 72 if (err < 0) 73 return err; 74 75 if (tb[TCA_DRR_QUANTUM]) { 76 quantum = nla_get_u32(tb[TCA_DRR_QUANTUM]); 77 if (quantum == 0) { 78 NL_SET_ERR_MSG(extack, "Specified DRR quantum cannot be zero"); 79 return -EINVAL; 80 } 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, NULL, 87 &cl->rate_est, 88 NULL, 89 qdisc_root_sleeping_running(sch), 90 tca[TCA_RATE]); 91 if (err) { 92 NL_SET_ERR_MSG(extack, "Failed to replace estimator"); 93 return err; 94 } 95 } 96 97 sch_tree_lock(sch); 98 if (tb[TCA_DRR_QUANTUM]) 99 cl->quantum = quantum; 100 sch_tree_unlock(sch); 101 102 return 0; 103 } 104 105 cl = kzalloc(sizeof(struct drr_class), GFP_KERNEL); 106 if (cl == NULL) 107 return -ENOBUFS; 108 109 cl->common.classid = classid; 110 cl->quantum = quantum; 111 cl->qdisc = qdisc_create_dflt(sch->dev_queue, 112 &pfifo_qdisc_ops, classid, 113 NULL); 114 if (cl->qdisc == NULL) 115 cl->qdisc = &noop_qdisc; 116 else 117 qdisc_hash_add(cl->qdisc, true); 118 119 if (tca[TCA_RATE]) { 120 err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est, 121 NULL, 122 qdisc_root_sleeping_running(sch), 123 tca[TCA_RATE]); 124 if (err) { 125 NL_SET_ERR_MSG(extack, "Failed to replace estimator"); 126 qdisc_put(cl->qdisc); 127 kfree(cl); 128 return err; 129 } 130 } 131 132 sch_tree_lock(sch); 133 qdisc_class_hash_insert(&q->clhash, &cl->common); 134 sch_tree_unlock(sch); 135 136 qdisc_class_hash_grow(sch, &q->clhash); 137 138 *arg = (unsigned long)cl; 139 return 0; 140 } 141 142 static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl) 143 { 144 gen_kill_estimator(&cl->rate_est); 145 qdisc_put(cl->qdisc); 146 kfree(cl); 147 } 148 149 static int drr_delete_class(struct Qdisc *sch, unsigned long arg) 150 { 151 struct drr_sched *q = qdisc_priv(sch); 152 struct drr_class *cl = (struct drr_class *)arg; 153 154 if (cl->filter_cnt > 0) 155 return -EBUSY; 156 157 sch_tree_lock(sch); 158 159 qdisc_purge_queue(cl->qdisc); 160 qdisc_class_hash_remove(&q->clhash, &cl->common); 161 162 sch_tree_unlock(sch); 163 164 drr_destroy_class(sch, cl); 165 return 0; 166 } 167 168 static unsigned long drr_search_class(struct Qdisc *sch, u32 classid) 169 { 170 return (unsigned long)drr_find_class(sch, classid); 171 } 172 173 static struct tcf_block *drr_tcf_block(struct Qdisc *sch, unsigned long cl, 174 struct netlink_ext_ack *extack) 175 { 176 struct drr_sched *q = qdisc_priv(sch); 177 178 if (cl) { 179 NL_SET_ERR_MSG(extack, "DRR classid must be zero"); 180 return NULL; 181 } 182 183 return q->block; 184 } 185 186 static unsigned long drr_bind_tcf(struct Qdisc *sch, unsigned long parent, 187 u32 classid) 188 { 189 struct drr_class *cl = drr_find_class(sch, classid); 190 191 if (cl != NULL) 192 cl->filter_cnt++; 193 194 return (unsigned long)cl; 195 } 196 197 static void drr_unbind_tcf(struct Qdisc *sch, unsigned long arg) 198 { 199 struct drr_class *cl = (struct drr_class *)arg; 200 201 cl->filter_cnt--; 202 } 203 204 static int drr_graft_class(struct Qdisc *sch, unsigned long arg, 205 struct Qdisc *new, struct Qdisc **old, 206 struct netlink_ext_ack *extack) 207 { 208 struct drr_class *cl = (struct drr_class *)arg; 209 210 if (new == NULL) { 211 new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, 212 cl->common.classid, NULL); 213 if (new == NULL) 214 new = &noop_qdisc; 215 } 216 217 *old = qdisc_replace(sch, new, &cl->qdisc); 218 return 0; 219 } 220 221 static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg) 222 { 223 struct drr_class *cl = (struct drr_class *)arg; 224 225 return cl->qdisc; 226 } 227 228 static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg) 229 { 230 struct drr_class *cl = (struct drr_class *)arg; 231 232 list_del(&cl->alist); 233 } 234 235 static int drr_dump_class(struct Qdisc *sch, unsigned long arg, 236 struct sk_buff *skb, struct tcmsg *tcm) 237 { 238 struct drr_class *cl = (struct drr_class *)arg; 239 struct nlattr *nest; 240 241 tcm->tcm_parent = TC_H_ROOT; 242 tcm->tcm_handle = cl->common.classid; 243 tcm->tcm_info = cl->qdisc->handle; 244 245 nest = nla_nest_start_noflag(skb, TCA_OPTIONS); 246 if (nest == NULL) 247 goto nla_put_failure; 248 if (nla_put_u32(skb, TCA_DRR_QUANTUM, cl->quantum)) 249 goto nla_put_failure; 250 return nla_nest_end(skb, nest); 251 252 nla_put_failure: 253 nla_nest_cancel(skb, nest); 254 return -EMSGSIZE; 255 } 256 257 static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg, 258 struct gnet_dump *d) 259 { 260 struct drr_class *cl = (struct drr_class *)arg; 261 __u32 qlen = qdisc_qlen_sum(cl->qdisc); 262 struct Qdisc *cl_q = cl->qdisc; 263 struct tc_drr_stats xstats; 264 265 memset(&xstats, 0, sizeof(xstats)); 266 if (qlen) 267 xstats.deficit = cl->deficit; 268 269 if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), 270 d, NULL, &cl->bstats) < 0 || 271 gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 || 272 gnet_stats_copy_queue(d, cl_q->cpu_qstats, &cl_q->qstats, qlen) < 0) 273 return -1; 274 275 return gnet_stats_copy_app(d, &xstats, sizeof(xstats)); 276 } 277 278 static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg) 279 { 280 struct drr_sched *q = qdisc_priv(sch); 281 struct drr_class *cl; 282 unsigned int i; 283 284 if (arg->stop) 285 return; 286 287 for (i = 0; i < q->clhash.hashsize; i++) { 288 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { 289 if (arg->count < arg->skip) { 290 arg->count++; 291 continue; 292 } 293 if (arg->fn(sch, (unsigned long)cl, arg) < 0) { 294 arg->stop = 1; 295 return; 296 } 297 arg->count++; 298 } 299 } 300 } 301 302 static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch, 303 int *qerr) 304 { 305 struct drr_sched *q = qdisc_priv(sch); 306 struct drr_class *cl; 307 struct tcf_result res; 308 struct tcf_proto *fl; 309 int result; 310 311 if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) { 312 cl = drr_find_class(sch, skb->priority); 313 if (cl != NULL) 314 return cl; 315 } 316 317 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; 318 fl = rcu_dereference_bh(q->filter_list); 319 result = tcf_classify(skb, fl, &res, false); 320 if (result >= 0) { 321 #ifdef CONFIG_NET_CLS_ACT 322 switch (result) { 323 case TC_ACT_QUEUED: 324 case TC_ACT_STOLEN: 325 case TC_ACT_TRAP: 326 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN; 327 /* fall through */ 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 struct sk_buff **to_free) 342 { 343 unsigned int len = qdisc_pkt_len(skb); 344 struct drr_sched *q = qdisc_priv(sch); 345 struct drr_class *cl; 346 int err = 0; 347 bool first; 348 349 cl = drr_classify(skb, sch, &err); 350 if (cl == NULL) { 351 if (err & __NET_XMIT_BYPASS) 352 qdisc_qstats_drop(sch); 353 __qdisc_drop(skb, to_free); 354 return err; 355 } 356 357 first = !cl->qdisc->q.qlen; 358 err = qdisc_enqueue(skb, cl->qdisc, to_free); 359 if (unlikely(err != NET_XMIT_SUCCESS)) { 360 if (net_xmit_drop_count(err)) { 361 cl->qstats.drops++; 362 qdisc_qstats_drop(sch); 363 } 364 return err; 365 } 366 367 if (first) { 368 list_add_tail(&cl->alist, &q->active); 369 cl->deficit = cl->quantum; 370 } 371 372 sch->qstats.backlog += len; 373 sch->q.qlen++; 374 return err; 375 } 376 377 static struct sk_buff *drr_dequeue(struct Qdisc *sch) 378 { 379 struct drr_sched *q = qdisc_priv(sch); 380 struct drr_class *cl; 381 struct sk_buff *skb; 382 unsigned int len; 383 384 if (list_empty(&q->active)) 385 goto out; 386 while (1) { 387 cl = list_first_entry(&q->active, struct drr_class, alist); 388 skb = cl->qdisc->ops->peek(cl->qdisc); 389 if (skb == NULL) { 390 qdisc_warn_nonwc(__func__, cl->qdisc); 391 goto out; 392 } 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 (unlikely(skb == NULL)) 399 goto out; 400 if (cl->qdisc->q.qlen == 0) 401 list_del(&cl->alist); 402 403 bstats_update(&cl->bstats, skb); 404 qdisc_bstats_update(sch, skb); 405 qdisc_qstats_backlog_dec(sch, skb); 406 sch->q.qlen--; 407 return skb; 408 } 409 410 cl->deficit += cl->quantum; 411 list_move_tail(&cl->alist, &q->active); 412 } 413 out: 414 return NULL; 415 } 416 417 static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt, 418 struct netlink_ext_ack *extack) 419 { 420 struct drr_sched *q = qdisc_priv(sch); 421 int err; 422 423 err = tcf_block_get(&q->block, &q->filter_list, sch, extack); 424 if (err) 425 return err; 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 unsigned int i; 438 439 for (i = 0; i < q->clhash.hashsize; i++) { 440 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { 441 if (cl->qdisc->q.qlen) 442 list_del(&cl->alist); 443 qdisc_reset(cl->qdisc); 444 } 445 } 446 sch->qstats.backlog = 0; 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 *next; 455 unsigned int i; 456 457 tcf_block_put(q->block); 458 459 for (i = 0; i < q->clhash.hashsize; i++) { 460 hlist_for_each_entry_safe(cl, 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 .find = drr_search_class, 471 .tcf_block = drr_tcf_block, 472 .bind_tcf = drr_bind_tcf, 473 .unbind_tcf = drr_unbind_tcf, 474 .graft = drr_graft_class, 475 .leaf = drr_class_leaf, 476 .qlen_notify = drr_qlen_notify, 477 .dump = drr_dump_class, 478 .dump_stats = drr_dump_class_stats, 479 .walk = drr_walk, 480 }; 481 482 static struct Qdisc_ops drr_qdisc_ops __read_mostly = { 483 .cl_ops = &drr_class_ops, 484 .id = "drr", 485 .priv_size = sizeof(struct drr_sched), 486 .enqueue = drr_enqueue, 487 .dequeue = drr_dequeue, 488 .peek = qdisc_peek_dequeued, 489 .init = drr_init_qdisc, 490 .reset = drr_reset_qdisc, 491 .destroy = drr_destroy_qdisc, 492 .owner = THIS_MODULE, 493 }; 494 495 static int __init drr_init(void) 496 { 497 return register_qdisc(&drr_qdisc_ops); 498 } 499 500 static void __exit drr_exit(void) 501 { 502 unregister_qdisc(&drr_qdisc_ops); 503 } 504 505 module_init(drr_init); 506 module_exit(drr_exit); 507 MODULE_LICENSE("GPL"); 508