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 21 struct gnet_stats_basic_sync bstats; 22 struct gnet_stats_queue qstats; 23 struct net_rate_estimator __rcu *rate_est; 24 struct list_head alist; 25 struct Qdisc *qdisc; 26 27 u32 quantum; 28 u32 deficit; 29 }; 30 31 struct drr_sched { 32 struct list_head active; 33 struct tcf_proto __rcu *filter_list; 34 struct tcf_block *block; 35 struct Qdisc_class_hash clhash; 36 }; 37 38 static bool cl_is_active(struct drr_class *cl) 39 { 40 return !list_empty(&cl->alist); 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 const struct nla_policy drr_policy[TCA_DRR_MAX + 1] = { 55 [TCA_DRR_QUANTUM] = { .type = NLA_U32 }, 56 }; 57 58 static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 59 struct nlattr **tca, unsigned long *arg, 60 struct netlink_ext_ack *extack) 61 { 62 struct drr_sched *q = qdisc_priv(sch); 63 struct drr_class *cl = (struct drr_class *)*arg; 64 struct nlattr *opt = tca[TCA_OPTIONS]; 65 struct nlattr *tb[TCA_DRR_MAX + 1]; 66 u32 quantum; 67 int err; 68 69 if (!opt) { 70 NL_SET_ERR_MSG(extack, "DRR options are required for this operation"); 71 return -EINVAL; 72 } 73 74 err = nla_parse_nested_deprecated(tb, TCA_DRR_MAX, opt, drr_policy, 75 extack); 76 if (err < 0) 77 return err; 78 79 if (tb[TCA_DRR_QUANTUM]) { 80 quantum = nla_get_u32(tb[TCA_DRR_QUANTUM]); 81 if (quantum == 0) { 82 NL_SET_ERR_MSG(extack, "Specified DRR quantum cannot be zero"); 83 return -EINVAL; 84 } 85 } else 86 quantum = psched_mtu(qdisc_dev(sch)); 87 88 if (cl != NULL) { 89 if (tca[TCA_RATE]) { 90 err = gen_replace_estimator(&cl->bstats, NULL, 91 &cl->rate_est, 92 NULL, true, 93 tca[TCA_RATE]); 94 if (err) { 95 NL_SET_ERR_MSG(extack, "Failed to replace estimator"); 96 return err; 97 } 98 } 99 100 sch_tree_lock(sch); 101 if (tb[TCA_DRR_QUANTUM]) 102 cl->quantum = quantum; 103 sch_tree_unlock(sch); 104 105 return 0; 106 } 107 108 cl = kzalloc(sizeof(struct drr_class), GFP_KERNEL); 109 if (cl == NULL) 110 return -ENOBUFS; 111 112 gnet_stats_basic_sync_init(&cl->bstats); 113 INIT_LIST_HEAD(&cl->alist); 114 cl->common.classid = classid; 115 cl->quantum = quantum; 116 cl->qdisc = qdisc_create_dflt(sch->dev_queue, 117 &pfifo_qdisc_ops, classid, 118 NULL); 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, true, tca[TCA_RATE]); 127 if (err) { 128 NL_SET_ERR_MSG(extack, "Failed to replace estimator"); 129 qdisc_put(cl->qdisc); 130 kfree(cl); 131 return err; 132 } 133 } 134 135 sch_tree_lock(sch); 136 qdisc_class_hash_insert(&q->clhash, &cl->common); 137 sch_tree_unlock(sch); 138 139 qdisc_class_hash_grow(sch, &q->clhash); 140 141 *arg = (unsigned long)cl; 142 return 0; 143 } 144 145 static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl) 146 { 147 gen_kill_estimator(&cl->rate_est); 148 qdisc_put(cl->qdisc); 149 kfree(cl); 150 } 151 152 static int drr_delete_class(struct Qdisc *sch, unsigned long arg, 153 struct netlink_ext_ack *extack) 154 { 155 struct drr_sched *q = qdisc_priv(sch); 156 struct drr_class *cl = (struct drr_class *)arg; 157 158 if (qdisc_class_in_use(&cl->common)) { 159 NL_SET_ERR_MSG(extack, "DRR class is in use"); 160 return -EBUSY; 161 } 162 163 sch_tree_lock(sch); 164 165 qdisc_purge_queue(cl->qdisc); 166 qdisc_class_hash_remove(&q->clhash, &cl->common); 167 168 sch_tree_unlock(sch); 169 170 drr_destroy_class(sch, cl); 171 return 0; 172 } 173 174 static unsigned long drr_search_class(struct Qdisc *sch, u32 classid) 175 { 176 return (unsigned long)drr_find_class(sch, classid); 177 } 178 179 static struct tcf_block *drr_tcf_block(struct Qdisc *sch, unsigned long cl, 180 struct netlink_ext_ack *extack) 181 { 182 struct drr_sched *q = qdisc_priv(sch); 183 184 if (cl) { 185 NL_SET_ERR_MSG(extack, "DRR classid must be zero"); 186 return NULL; 187 } 188 189 return q->block; 190 } 191 192 static unsigned long drr_bind_tcf(struct Qdisc *sch, unsigned long parent, 193 u32 classid) 194 { 195 struct drr_class *cl = drr_find_class(sch, classid); 196 197 if (cl) 198 qdisc_class_get(&cl->common); 199 200 return (unsigned long)cl; 201 } 202 203 static void drr_unbind_tcf(struct Qdisc *sch, unsigned long arg) 204 { 205 struct drr_class *cl = (struct drr_class *)arg; 206 207 qdisc_class_put(&cl->common); 208 } 209 210 static int drr_graft_class(struct Qdisc *sch, unsigned long arg, 211 struct Qdisc *new, struct Qdisc **old, 212 struct netlink_ext_ack *extack) 213 { 214 struct drr_class *cl = (struct drr_class *)arg; 215 216 if (new == NULL) { 217 new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, 218 cl->common.classid, NULL); 219 if (new == NULL) 220 new = &noop_qdisc; 221 } 222 223 *old = qdisc_replace(sch, new, &cl->qdisc); 224 return 0; 225 } 226 227 static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg) 228 { 229 struct drr_class *cl = (struct drr_class *)arg; 230 231 return cl->qdisc; 232 } 233 234 static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg) 235 { 236 struct drr_class *cl = (struct drr_class *)arg; 237 238 list_del_init(&cl->alist); 239 } 240 241 static int drr_dump_class(struct Qdisc *sch, unsigned long arg, 242 struct sk_buff *skb, struct tcmsg *tcm) 243 { 244 struct drr_class *cl = (struct drr_class *)arg; 245 struct nlattr *nest; 246 247 tcm->tcm_parent = TC_H_ROOT; 248 tcm->tcm_handle = cl->common.classid; 249 tcm->tcm_info = cl->qdisc->handle; 250 251 nest = nla_nest_start_noflag(skb, TCA_OPTIONS); 252 if (nest == NULL) 253 goto nla_put_failure; 254 if (nla_put_u32(skb, TCA_DRR_QUANTUM, cl->quantum)) 255 goto nla_put_failure; 256 return nla_nest_end(skb, nest); 257 258 nla_put_failure: 259 nla_nest_cancel(skb, nest); 260 return -EMSGSIZE; 261 } 262 263 static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg, 264 struct gnet_dump *d) 265 { 266 struct drr_class *cl = (struct drr_class *)arg; 267 __u32 qlen = qdisc_qlen_sum(cl->qdisc); 268 struct Qdisc *cl_q = cl->qdisc; 269 struct tc_drr_stats xstats; 270 271 memset(&xstats, 0, sizeof(xstats)); 272 if (qlen) 273 xstats.deficit = cl->deficit; 274 275 if (gnet_stats_copy_basic(d, NULL, &cl->bstats, true) < 0 || 276 gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 || 277 gnet_stats_copy_queue(d, cl_q->cpu_qstats, &cl_q->qstats, qlen) < 0) 278 return -1; 279 280 return gnet_stats_copy_app(d, &xstats, sizeof(xstats)); 281 } 282 283 static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg) 284 { 285 struct drr_sched *q = qdisc_priv(sch); 286 struct drr_class *cl; 287 unsigned int i; 288 289 if (arg->stop) 290 return; 291 292 for (i = 0; i < q->clhash.hashsize; i++) { 293 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { 294 if (!tc_qdisc_stats_dump(sch, (unsigned long)cl, arg)) 295 return; 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; 345 346 cl = drr_classify(skb, sch, &err); 347 if (cl == NULL) { 348 if (err & __NET_XMIT_BYPASS) 349 qdisc_qstats_drop(sch); 350 __qdisc_drop(skb, to_free); 351 return err; 352 } 353 354 err = qdisc_enqueue(skb, cl->qdisc, to_free); 355 if (unlikely(err != NET_XMIT_SUCCESS)) { 356 if (net_xmit_drop_count(err)) { 357 cl->qstats.drops++; 358 qdisc_qstats_drop(sch); 359 } 360 return err; 361 } 362 363 if (!cl_is_active(cl)) { 364 list_add_tail(&cl->alist, &q->active); 365 cl->deficit = cl->quantum; 366 } 367 368 sch->qstats.backlog += len; 369 sch->q.qlen++; 370 return err; 371 } 372 373 static struct sk_buff *drr_dequeue(struct Qdisc *sch) 374 { 375 struct drr_sched *q = qdisc_priv(sch); 376 struct drr_class *cl; 377 struct sk_buff *skb; 378 unsigned int len; 379 380 if (list_empty(&q->active)) 381 goto out; 382 while (1) { 383 cl = list_first_entry(&q->active, struct drr_class, alist); 384 skb = cl->qdisc->ops->peek(cl->qdisc); 385 if (skb == NULL) { 386 qdisc_warn_nonwc(__func__, cl->qdisc); 387 goto out; 388 } 389 390 len = qdisc_pkt_len(skb); 391 if (len <= cl->deficit) { 392 cl->deficit -= len; 393 skb = qdisc_dequeue_peeked(cl->qdisc); 394 if (unlikely(skb == NULL)) 395 goto out; 396 if (cl->qdisc->q.qlen == 0) 397 list_del_init(&cl->alist); 398 399 bstats_update(&cl->bstats, skb); 400 qdisc_bstats_update(sch, skb); 401 qdisc_qstats_backlog_dec(sch, skb); 402 sch->q.qlen--; 403 return skb; 404 } 405 406 cl->deficit += cl->quantum; 407 list_move_tail(&cl->alist, &q->active); 408 } 409 out: 410 return NULL; 411 } 412 413 static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt, 414 struct netlink_ext_ack *extack) 415 { 416 struct drr_sched *q = qdisc_priv(sch); 417 int err; 418 419 err = tcf_block_get(&q->block, &q->filter_list, sch, extack); 420 if (err) 421 return err; 422 err = qdisc_class_hash_init(&q->clhash); 423 if (err < 0) 424 return err; 425 INIT_LIST_HEAD(&q->active); 426 return 0; 427 } 428 429 static void drr_reset_qdisc(struct Qdisc *sch) 430 { 431 struct drr_sched *q = qdisc_priv(sch); 432 struct drr_class *cl; 433 unsigned int i; 434 435 for (i = 0; i < q->clhash.hashsize; i++) { 436 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { 437 if (cl->qdisc->q.qlen) 438 list_del_init(&cl->alist); 439 qdisc_reset(cl->qdisc); 440 } 441 } 442 } 443 444 static void drr_destroy_qdisc(struct Qdisc *sch) 445 { 446 struct drr_sched *q = qdisc_priv(sch); 447 struct drr_class *cl; 448 struct hlist_node *next; 449 unsigned int i; 450 451 tcf_block_put(q->block); 452 453 for (i = 0; i < q->clhash.hashsize; i++) { 454 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i], 455 common.hnode) 456 drr_destroy_class(sch, cl); 457 } 458 qdisc_class_hash_destroy(&q->clhash); 459 } 460 461 static const struct Qdisc_class_ops drr_class_ops = { 462 .change = drr_change_class, 463 .delete = drr_delete_class, 464 .find = drr_search_class, 465 .tcf_block = drr_tcf_block, 466 .bind_tcf = drr_bind_tcf, 467 .unbind_tcf = drr_unbind_tcf, 468 .graft = drr_graft_class, 469 .leaf = drr_class_leaf, 470 .qlen_notify = drr_qlen_notify, 471 .dump = drr_dump_class, 472 .dump_stats = drr_dump_class_stats, 473 .walk = drr_walk, 474 }; 475 476 static struct Qdisc_ops drr_qdisc_ops __read_mostly = { 477 .cl_ops = &drr_class_ops, 478 .id = "drr", 479 .priv_size = sizeof(struct drr_sched), 480 .enqueue = drr_enqueue, 481 .dequeue = drr_dequeue, 482 .peek = qdisc_peek_dequeued, 483 .init = drr_init_qdisc, 484 .reset = drr_reset_qdisc, 485 .destroy = drr_destroy_qdisc, 486 .owner = THIS_MODULE, 487 }; 488 MODULE_ALIAS_NET_SCH("drr"); 489 490 static int __init drr_init(void) 491 { 492 return register_qdisc(&drr_qdisc_ops); 493 } 494 495 static void __exit drr_exit(void) 496 { 497 unregister_qdisc(&drr_qdisc_ops); 498 } 499 500 module_init(drr_init); 501 module_exit(drr_exit); 502 MODULE_LICENSE("GPL"); 503 MODULE_DESCRIPTION("Deficit Round Robin scheduler"); 504