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