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 struct netlink_ext_ack *extack) 151 { 152 struct drr_sched *q = qdisc_priv(sch); 153 struct drr_class *cl = (struct drr_class *)arg; 154 155 if (cl->filter_cnt > 0) 156 return -EBUSY; 157 158 sch_tree_lock(sch); 159 160 qdisc_purge_queue(cl->qdisc); 161 qdisc_class_hash_remove(&q->clhash, &cl->common); 162 163 sch_tree_unlock(sch); 164 165 drr_destroy_class(sch, cl); 166 return 0; 167 } 168 169 static unsigned long drr_search_class(struct Qdisc *sch, u32 classid) 170 { 171 return (unsigned long)drr_find_class(sch, classid); 172 } 173 174 static struct tcf_block *drr_tcf_block(struct Qdisc *sch, unsigned long cl, 175 struct netlink_ext_ack *extack) 176 { 177 struct drr_sched *q = qdisc_priv(sch); 178 179 if (cl) { 180 NL_SET_ERR_MSG(extack, "DRR classid must be zero"); 181 return NULL; 182 } 183 184 return q->block; 185 } 186 187 static unsigned long drr_bind_tcf(struct Qdisc *sch, unsigned long parent, 188 u32 classid) 189 { 190 struct drr_class *cl = drr_find_class(sch, classid); 191 192 if (cl != NULL) 193 cl->filter_cnt++; 194 195 return (unsigned long)cl; 196 } 197 198 static void drr_unbind_tcf(struct Qdisc *sch, unsigned long arg) 199 { 200 struct drr_class *cl = (struct drr_class *)arg; 201 202 cl->filter_cnt--; 203 } 204 205 static int drr_graft_class(struct Qdisc *sch, unsigned long arg, 206 struct Qdisc *new, struct Qdisc **old, 207 struct netlink_ext_ack *extack) 208 { 209 struct drr_class *cl = (struct drr_class *)arg; 210 211 if (new == NULL) { 212 new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, 213 cl->common.classid, NULL); 214 if (new == NULL) 215 new = &noop_qdisc; 216 } 217 218 *old = qdisc_replace(sch, new, &cl->qdisc); 219 return 0; 220 } 221 222 static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg) 223 { 224 struct drr_class *cl = (struct drr_class *)arg; 225 226 return cl->qdisc; 227 } 228 229 static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg) 230 { 231 struct drr_class *cl = (struct drr_class *)arg; 232 233 list_del(&cl->alist); 234 } 235 236 static int drr_dump_class(struct Qdisc *sch, unsigned long arg, 237 struct sk_buff *skb, struct tcmsg *tcm) 238 { 239 struct drr_class *cl = (struct drr_class *)arg; 240 struct nlattr *nest; 241 242 tcm->tcm_parent = TC_H_ROOT; 243 tcm->tcm_handle = cl->common.classid; 244 tcm->tcm_info = cl->qdisc->handle; 245 246 nest = nla_nest_start_noflag(skb, TCA_OPTIONS); 247 if (nest == NULL) 248 goto nla_put_failure; 249 if (nla_put_u32(skb, TCA_DRR_QUANTUM, cl->quantum)) 250 goto nla_put_failure; 251 return nla_nest_end(skb, nest); 252 253 nla_put_failure: 254 nla_nest_cancel(skb, nest); 255 return -EMSGSIZE; 256 } 257 258 static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg, 259 struct gnet_dump *d) 260 { 261 struct drr_class *cl = (struct drr_class *)arg; 262 __u32 qlen = qdisc_qlen_sum(cl->qdisc); 263 struct Qdisc *cl_q = cl->qdisc; 264 struct tc_drr_stats xstats; 265 266 memset(&xstats, 0, sizeof(xstats)); 267 if (qlen) 268 xstats.deficit = cl->deficit; 269 270 if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), 271 d, NULL, &cl->bstats) < 0 || 272 gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 || 273 gnet_stats_copy_queue(d, cl_q->cpu_qstats, &cl_q->qstats, qlen) < 0) 274 return -1; 275 276 return gnet_stats_copy_app(d, &xstats, sizeof(xstats)); 277 } 278 279 static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg) 280 { 281 struct drr_sched *q = qdisc_priv(sch); 282 struct drr_class *cl; 283 unsigned int i; 284 285 if (arg->stop) 286 return; 287 288 for (i = 0; i < q->clhash.hashsize; i++) { 289 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { 290 if (arg->count < arg->skip) { 291 arg->count++; 292 continue; 293 } 294 if (arg->fn(sch, (unsigned long)cl, arg) < 0) { 295 arg->stop = 1; 296 return; 297 } 298 arg->count++; 299 } 300 } 301 } 302 303 static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch, 304 int *qerr) 305 { 306 struct drr_sched *q = qdisc_priv(sch); 307 struct drr_class *cl; 308 struct tcf_result res; 309 struct tcf_proto *fl; 310 int result; 311 312 if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) { 313 cl = drr_find_class(sch, skb->priority); 314 if (cl != NULL) 315 return cl; 316 } 317 318 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; 319 fl = rcu_dereference_bh(q->filter_list); 320 result = tcf_classify(skb, NULL, fl, &res, false); 321 if (result >= 0) { 322 #ifdef CONFIG_NET_CLS_ACT 323 switch (result) { 324 case TC_ACT_QUEUED: 325 case TC_ACT_STOLEN: 326 case TC_ACT_TRAP: 327 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN; 328 fallthrough; 329 case TC_ACT_SHOT: 330 return NULL; 331 } 332 #endif 333 cl = (struct drr_class *)res.class; 334 if (cl == NULL) 335 cl = drr_find_class(sch, res.classid); 336 return cl; 337 } 338 return NULL; 339 } 340 341 static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch, 342 struct sk_buff **to_free) 343 { 344 unsigned int len = qdisc_pkt_len(skb); 345 struct drr_sched *q = qdisc_priv(sch); 346 struct drr_class *cl; 347 int err = 0; 348 bool first; 349 350 cl = drr_classify(skb, sch, &err); 351 if (cl == NULL) { 352 if (err & __NET_XMIT_BYPASS) 353 qdisc_qstats_drop(sch); 354 __qdisc_drop(skb, to_free); 355 return err; 356 } 357 358 first = !cl->qdisc->q.qlen; 359 err = qdisc_enqueue(skb, cl->qdisc, to_free); 360 if (unlikely(err != NET_XMIT_SUCCESS)) { 361 if (net_xmit_drop_count(err)) { 362 cl->qstats.drops++; 363 qdisc_qstats_drop(sch); 364 } 365 return err; 366 } 367 368 if (first) { 369 list_add_tail(&cl->alist, &q->active); 370 cl->deficit = cl->quantum; 371 } 372 373 sch->qstats.backlog += len; 374 sch->q.qlen++; 375 return err; 376 } 377 378 static struct sk_buff *drr_dequeue(struct Qdisc *sch) 379 { 380 struct drr_sched *q = qdisc_priv(sch); 381 struct drr_class *cl; 382 struct sk_buff *skb; 383 unsigned int len; 384 385 if (list_empty(&q->active)) 386 goto out; 387 while (1) { 388 cl = list_first_entry(&q->active, struct drr_class, alist); 389 skb = cl->qdisc->ops->peek(cl->qdisc); 390 if (skb == NULL) { 391 qdisc_warn_nonwc(__func__, cl->qdisc); 392 goto out; 393 } 394 395 len = qdisc_pkt_len(skb); 396 if (len <= cl->deficit) { 397 cl->deficit -= len; 398 skb = qdisc_dequeue_peeked(cl->qdisc); 399 if (unlikely(skb == NULL)) 400 goto out; 401 if (cl->qdisc->q.qlen == 0) 402 list_del(&cl->alist); 403 404 bstats_update(&cl->bstats, skb); 405 qdisc_bstats_update(sch, skb); 406 qdisc_qstats_backlog_dec(sch, skb); 407 sch->q.qlen--; 408 return skb; 409 } 410 411 cl->deficit += cl->quantum; 412 list_move_tail(&cl->alist, &q->active); 413 } 414 out: 415 return NULL; 416 } 417 418 static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt, 419 struct netlink_ext_ack *extack) 420 { 421 struct drr_sched *q = qdisc_priv(sch); 422 int err; 423 424 err = tcf_block_get(&q->block, &q->filter_list, sch, extack); 425 if (err) 426 return err; 427 err = qdisc_class_hash_init(&q->clhash); 428 if (err < 0) 429 return err; 430 INIT_LIST_HEAD(&q->active); 431 return 0; 432 } 433 434 static void drr_reset_qdisc(struct Qdisc *sch) 435 { 436 struct drr_sched *q = qdisc_priv(sch); 437 struct drr_class *cl; 438 unsigned int i; 439 440 for (i = 0; i < q->clhash.hashsize; i++) { 441 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { 442 if (cl->qdisc->q.qlen) 443 list_del(&cl->alist); 444 qdisc_reset(cl->qdisc); 445 } 446 } 447 sch->qstats.backlog = 0; 448 sch->q.qlen = 0; 449 } 450 451 static void drr_destroy_qdisc(struct Qdisc *sch) 452 { 453 struct drr_sched *q = qdisc_priv(sch); 454 struct drr_class *cl; 455 struct hlist_node *next; 456 unsigned int i; 457 458 tcf_block_put(q->block); 459 460 for (i = 0; i < q->clhash.hashsize; i++) { 461 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i], 462 common.hnode) 463 drr_destroy_class(sch, cl); 464 } 465 qdisc_class_hash_destroy(&q->clhash); 466 } 467 468 static const struct Qdisc_class_ops drr_class_ops = { 469 .change = drr_change_class, 470 .delete = drr_delete_class, 471 .find = drr_search_class, 472 .tcf_block = drr_tcf_block, 473 .bind_tcf = drr_bind_tcf, 474 .unbind_tcf = drr_unbind_tcf, 475 .graft = drr_graft_class, 476 .leaf = drr_class_leaf, 477 .qlen_notify = drr_qlen_notify, 478 .dump = drr_dump_class, 479 .dump_stats = drr_dump_class_stats, 480 .walk = drr_walk, 481 }; 482 483 static struct Qdisc_ops drr_qdisc_ops __read_mostly = { 484 .cl_ops = &drr_class_ops, 485 .id = "drr", 486 .priv_size = sizeof(struct drr_sched), 487 .enqueue = drr_enqueue, 488 .dequeue = drr_dequeue, 489 .peek = qdisc_peek_dequeued, 490 .init = drr_init_qdisc, 491 .reset = drr_reset_qdisc, 492 .destroy = drr_destroy_qdisc, 493 .owner = THIS_MODULE, 494 }; 495 496 static int __init drr_init(void) 497 { 498 return register_qdisc(&drr_qdisc_ops); 499 } 500 501 static void __exit drr_exit(void) 502 { 503 unregister_qdisc(&drr_qdisc_ops); 504 } 505 506 module_init(drr_init); 507 module_exit(drr_exit); 508 MODULE_LICENSE("GPL"); 509