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_sync 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 gnet_stats_basic_sync_init(&cl->bstats); 110 cl->common.classid = classid; 111 cl->quantum = quantum; 112 cl->qdisc = qdisc_create_dflt(sch->dev_queue, 113 &pfifo_qdisc_ops, classid, 114 NULL); 115 if (cl->qdisc == NULL) 116 cl->qdisc = &noop_qdisc; 117 else 118 qdisc_hash_add(cl->qdisc, true); 119 120 if (tca[TCA_RATE]) { 121 err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est, 122 NULL, 123 qdisc_root_sleeping_running(sch), 124 tca[TCA_RATE]); 125 if (err) { 126 NL_SET_ERR_MSG(extack, "Failed to replace estimator"); 127 qdisc_put(cl->qdisc); 128 kfree(cl); 129 return err; 130 } 131 } 132 133 sch_tree_lock(sch); 134 qdisc_class_hash_insert(&q->clhash, &cl->common); 135 sch_tree_unlock(sch); 136 137 qdisc_class_hash_grow(sch, &q->clhash); 138 139 *arg = (unsigned long)cl; 140 return 0; 141 } 142 143 static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl) 144 { 145 gen_kill_estimator(&cl->rate_est); 146 qdisc_put(cl->qdisc); 147 kfree(cl); 148 } 149 150 static int drr_delete_class(struct Qdisc *sch, unsigned long arg, 151 struct netlink_ext_ack *extack) 152 { 153 struct drr_sched *q = qdisc_priv(sch); 154 struct drr_class *cl = (struct drr_class *)arg; 155 156 if (cl->filter_cnt > 0) 157 return -EBUSY; 158 159 sch_tree_lock(sch); 160 161 qdisc_purge_queue(cl->qdisc); 162 qdisc_class_hash_remove(&q->clhash, &cl->common); 163 164 sch_tree_unlock(sch); 165 166 drr_destroy_class(sch, cl); 167 return 0; 168 } 169 170 static unsigned long drr_search_class(struct Qdisc *sch, u32 classid) 171 { 172 return (unsigned long)drr_find_class(sch, classid); 173 } 174 175 static struct tcf_block *drr_tcf_block(struct Qdisc *sch, unsigned long cl, 176 struct netlink_ext_ack *extack) 177 { 178 struct drr_sched *q = qdisc_priv(sch); 179 180 if (cl) { 181 NL_SET_ERR_MSG(extack, "DRR classid must be zero"); 182 return NULL; 183 } 184 185 return q->block; 186 } 187 188 static unsigned long drr_bind_tcf(struct Qdisc *sch, unsigned long parent, 189 u32 classid) 190 { 191 struct drr_class *cl = drr_find_class(sch, classid); 192 193 if (cl != NULL) 194 cl->filter_cnt++; 195 196 return (unsigned long)cl; 197 } 198 199 static void drr_unbind_tcf(struct Qdisc *sch, unsigned long arg) 200 { 201 struct drr_class *cl = (struct drr_class *)arg; 202 203 cl->filter_cnt--; 204 } 205 206 static int drr_graft_class(struct Qdisc *sch, unsigned long arg, 207 struct Qdisc *new, struct Qdisc **old, 208 struct netlink_ext_ack *extack) 209 { 210 struct drr_class *cl = (struct drr_class *)arg; 211 212 if (new == NULL) { 213 new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, 214 cl->common.classid, NULL); 215 if (new == NULL) 216 new = &noop_qdisc; 217 } 218 219 *old = qdisc_replace(sch, new, &cl->qdisc); 220 return 0; 221 } 222 223 static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg) 224 { 225 struct drr_class *cl = (struct drr_class *)arg; 226 227 return cl->qdisc; 228 } 229 230 static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg) 231 { 232 struct drr_class *cl = (struct drr_class *)arg; 233 234 list_del(&cl->alist); 235 } 236 237 static int drr_dump_class(struct Qdisc *sch, unsigned long arg, 238 struct sk_buff *skb, struct tcmsg *tcm) 239 { 240 struct drr_class *cl = (struct drr_class *)arg; 241 struct nlattr *nest; 242 243 tcm->tcm_parent = TC_H_ROOT; 244 tcm->tcm_handle = cl->common.classid; 245 tcm->tcm_info = cl->qdisc->handle; 246 247 nest = nla_nest_start_noflag(skb, TCA_OPTIONS); 248 if (nest == NULL) 249 goto nla_put_failure; 250 if (nla_put_u32(skb, TCA_DRR_QUANTUM, cl->quantum)) 251 goto nla_put_failure; 252 return nla_nest_end(skb, nest); 253 254 nla_put_failure: 255 nla_nest_cancel(skb, nest); 256 return -EMSGSIZE; 257 } 258 259 static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg, 260 struct gnet_dump *d) 261 { 262 struct drr_class *cl = (struct drr_class *)arg; 263 __u32 qlen = qdisc_qlen_sum(cl->qdisc); 264 struct Qdisc *cl_q = cl->qdisc; 265 struct tc_drr_stats xstats; 266 267 memset(&xstats, 0, sizeof(xstats)); 268 if (qlen) 269 xstats.deficit = cl->deficit; 270 271 if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), 272 d, NULL, &cl->bstats) < 0 || 273 gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 || 274 gnet_stats_copy_queue(d, cl_q->cpu_qstats, &cl_q->qstats, qlen) < 0) 275 return -1; 276 277 return gnet_stats_copy_app(d, &xstats, sizeof(xstats)); 278 } 279 280 static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg) 281 { 282 struct drr_sched *q = qdisc_priv(sch); 283 struct drr_class *cl; 284 unsigned int i; 285 286 if (arg->stop) 287 return; 288 289 for (i = 0; i < q->clhash.hashsize; i++) { 290 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { 291 if (arg->count < arg->skip) { 292 arg->count++; 293 continue; 294 } 295 if (arg->fn(sch, (unsigned long)cl, arg) < 0) { 296 arg->stop = 1; 297 return; 298 } 299 arg->count++; 300 } 301 } 302 } 303 304 static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch, 305 int *qerr) 306 { 307 struct drr_sched *q = qdisc_priv(sch); 308 struct drr_class *cl; 309 struct tcf_result res; 310 struct tcf_proto *fl; 311 int result; 312 313 if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) { 314 cl = drr_find_class(sch, skb->priority); 315 if (cl != NULL) 316 return cl; 317 } 318 319 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; 320 fl = rcu_dereference_bh(q->filter_list); 321 result = tcf_classify(skb, NULL, fl, &res, false); 322 if (result >= 0) { 323 #ifdef CONFIG_NET_CLS_ACT 324 switch (result) { 325 case TC_ACT_QUEUED: 326 case TC_ACT_STOLEN: 327 case TC_ACT_TRAP: 328 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN; 329 fallthrough; 330 case TC_ACT_SHOT: 331 return NULL; 332 } 333 #endif 334 cl = (struct drr_class *)res.class; 335 if (cl == NULL) 336 cl = drr_find_class(sch, res.classid); 337 return cl; 338 } 339 return NULL; 340 } 341 342 static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch, 343 struct sk_buff **to_free) 344 { 345 unsigned int len = qdisc_pkt_len(skb); 346 struct drr_sched *q = qdisc_priv(sch); 347 struct drr_class *cl; 348 int err = 0; 349 bool first; 350 351 cl = drr_classify(skb, sch, &err); 352 if (cl == NULL) { 353 if (err & __NET_XMIT_BYPASS) 354 qdisc_qstats_drop(sch); 355 __qdisc_drop(skb, to_free); 356 return err; 357 } 358 359 first = !cl->qdisc->q.qlen; 360 err = qdisc_enqueue(skb, cl->qdisc, to_free); 361 if (unlikely(err != NET_XMIT_SUCCESS)) { 362 if (net_xmit_drop_count(err)) { 363 cl->qstats.drops++; 364 qdisc_qstats_drop(sch); 365 } 366 return err; 367 } 368 369 if (first) { 370 list_add_tail(&cl->alist, &q->active); 371 cl->deficit = cl->quantum; 372 } 373 374 sch->qstats.backlog += len; 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 qdisc_warn_nonwc(__func__, cl->qdisc); 393 goto out; 394 } 395 396 len = qdisc_pkt_len(skb); 397 if (len <= cl->deficit) { 398 cl->deficit -= len; 399 skb = qdisc_dequeue_peeked(cl->qdisc); 400 if (unlikely(skb == NULL)) 401 goto out; 402 if (cl->qdisc->q.qlen == 0) 403 list_del(&cl->alist); 404 405 bstats_update(&cl->bstats, skb); 406 qdisc_bstats_update(sch, skb); 407 qdisc_qstats_backlog_dec(sch, skb); 408 sch->q.qlen--; 409 return skb; 410 } 411 412 cl->deficit += cl->quantum; 413 list_move_tail(&cl->alist, &q->active); 414 } 415 out: 416 return NULL; 417 } 418 419 static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt, 420 struct netlink_ext_ack *extack) 421 { 422 struct drr_sched *q = qdisc_priv(sch); 423 int err; 424 425 err = tcf_block_get(&q->block, &q->filter_list, sch, extack); 426 if (err) 427 return err; 428 err = qdisc_class_hash_init(&q->clhash); 429 if (err < 0) 430 return err; 431 INIT_LIST_HEAD(&q->active); 432 return 0; 433 } 434 435 static void drr_reset_qdisc(struct Qdisc *sch) 436 { 437 struct drr_sched *q = qdisc_priv(sch); 438 struct drr_class *cl; 439 unsigned int i; 440 441 for (i = 0; i < q->clhash.hashsize; i++) { 442 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { 443 if (cl->qdisc->q.qlen) 444 list_del(&cl->alist); 445 qdisc_reset(cl->qdisc); 446 } 447 } 448 sch->qstats.backlog = 0; 449 sch->q.qlen = 0; 450 } 451 452 static void drr_destroy_qdisc(struct Qdisc *sch) 453 { 454 struct drr_sched *q = qdisc_priv(sch); 455 struct drr_class *cl; 456 struct hlist_node *next; 457 unsigned int i; 458 459 tcf_block_put(q->block); 460 461 for (i = 0; i < q->clhash.hashsize; i++) { 462 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i], 463 common.hnode) 464 drr_destroy_class(sch, cl); 465 } 466 qdisc_class_hash_destroy(&q->clhash); 467 } 468 469 static const struct Qdisc_class_ops drr_class_ops = { 470 .change = drr_change_class, 471 .delete = drr_delete_class, 472 .find = drr_search_class, 473 .tcf_block = drr_tcf_block, 474 .bind_tcf = drr_bind_tcf, 475 .unbind_tcf = drr_unbind_tcf, 476 .graft = drr_graft_class, 477 .leaf = drr_class_leaf, 478 .qlen_notify = drr_qlen_notify, 479 .dump = drr_dump_class, 480 .dump_stats = drr_dump_class_stats, 481 .walk = drr_walk, 482 }; 483 484 static struct Qdisc_ops drr_qdisc_ops __read_mostly = { 485 .cl_ops = &drr_class_ops, 486 .id = "drr", 487 .priv_size = sizeof(struct drr_sched), 488 .enqueue = drr_enqueue, 489 .dequeue = drr_dequeue, 490 .peek = qdisc_peek_dequeued, 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"); 510