1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * net/sched/sch_red.c Random Early Detection queue. 4 * 5 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> 6 * 7 * Changes: 8 * J Hadi Salim 980914: computation fixes 9 * Alexey Makarenko <makar@phoenix.kharkov.ua> 990814: qave on idle link was calculated incorrectly. 10 * J Hadi Salim 980816: ECN support 11 */ 12 13 #include <linux/module.h> 14 #include <linux/types.h> 15 #include <linux/kernel.h> 16 #include <linux/skbuff.h> 17 #include <net/pkt_sched.h> 18 #include <net/pkt_cls.h> 19 #include <net/inet_ecn.h> 20 #include <net/red.h> 21 22 23 /* Parameters, settable by user: 24 ----------------------------- 25 26 limit - bytes (must be > qth_max + burst) 27 28 Hard limit on queue length, should be chosen >qth_max 29 to allow packet bursts. This parameter does not 30 affect the algorithms behaviour and can be chosen 31 arbitrarily high (well, less than ram size) 32 Really, this limit will never be reached 33 if RED works correctly. 34 */ 35 36 struct red_sched_data { 37 u32 limit; /* HARD maximal queue length */ 38 39 unsigned char flags; 40 /* Non-flags in tc_red_qopt.flags. */ 41 unsigned char userbits; 42 43 struct timer_list adapt_timer; 44 struct Qdisc *sch; 45 struct red_parms parms; 46 struct red_vars vars; 47 struct red_stats stats; 48 struct Qdisc *qdisc; 49 struct tcf_qevent qe_early_drop; 50 struct tcf_qevent qe_mark; 51 }; 52 53 #define TC_RED_SUPPORTED_FLAGS (TC_RED_HISTORIC_FLAGS | TC_RED_NODROP) 54 55 static inline int red_use_ecn(struct red_sched_data *q) 56 { 57 return q->flags & TC_RED_ECN; 58 } 59 60 static inline int red_use_harddrop(struct red_sched_data *q) 61 { 62 return q->flags & TC_RED_HARDDROP; 63 } 64 65 static int red_use_nodrop(struct red_sched_data *q) 66 { 67 return q->flags & TC_RED_NODROP; 68 } 69 70 static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch, 71 struct sk_buff **to_free) 72 { 73 struct red_sched_data *q = qdisc_priv(sch); 74 struct Qdisc *child = q->qdisc; 75 unsigned int len; 76 int ret; 77 78 q->vars.qavg = red_calc_qavg(&q->parms, 79 &q->vars, 80 child->qstats.backlog); 81 82 if (red_is_idling(&q->vars)) 83 red_end_of_idle_period(&q->vars); 84 85 switch (red_action(&q->parms, &q->vars, q->vars.qavg)) { 86 case RED_DONT_MARK: 87 break; 88 89 case RED_PROB_MARK: 90 qdisc_qstats_overlimit(sch); 91 if (!red_use_ecn(q)) { 92 q->stats.prob_drop++; 93 goto congestion_drop; 94 } 95 96 if (INET_ECN_set_ce(skb)) { 97 q->stats.prob_mark++; 98 skb = tcf_qevent_handle(&q->qe_mark, sch, skb, to_free, &ret); 99 if (!skb) 100 return NET_XMIT_CN | ret; 101 } else if (!red_use_nodrop(q)) { 102 q->stats.prob_drop++; 103 goto congestion_drop; 104 } 105 106 /* Non-ECT packet in ECN nodrop mode: queue it. */ 107 break; 108 109 case RED_HARD_MARK: 110 qdisc_qstats_overlimit(sch); 111 if (red_use_harddrop(q) || !red_use_ecn(q)) { 112 q->stats.forced_drop++; 113 goto congestion_drop; 114 } 115 116 if (INET_ECN_set_ce(skb)) { 117 q->stats.forced_mark++; 118 skb = tcf_qevent_handle(&q->qe_mark, sch, skb, to_free, &ret); 119 if (!skb) 120 return NET_XMIT_CN | ret; 121 } else if (!red_use_nodrop(q)) { 122 q->stats.forced_drop++; 123 goto congestion_drop; 124 } 125 126 /* Non-ECT packet in ECN nodrop mode: queue it. */ 127 break; 128 } 129 130 len = qdisc_pkt_len(skb); 131 ret = qdisc_enqueue(skb, child, to_free); 132 if (likely(ret == NET_XMIT_SUCCESS)) { 133 sch->qstats.backlog += len; 134 sch->q.qlen++; 135 } else if (net_xmit_drop_count(ret)) { 136 q->stats.pdrop++; 137 qdisc_qstats_drop(sch); 138 } 139 return ret; 140 141 congestion_drop: 142 skb = tcf_qevent_handle(&q->qe_early_drop, sch, skb, to_free, &ret); 143 if (!skb) 144 return NET_XMIT_CN | ret; 145 146 qdisc_drop(skb, sch, to_free); 147 return NET_XMIT_CN; 148 } 149 150 static struct sk_buff *red_dequeue(struct Qdisc *sch) 151 { 152 struct sk_buff *skb; 153 struct red_sched_data *q = qdisc_priv(sch); 154 struct Qdisc *child = q->qdisc; 155 156 skb = child->dequeue(child); 157 if (skb) { 158 qdisc_bstats_update(sch, skb); 159 qdisc_qstats_backlog_dec(sch, skb); 160 sch->q.qlen--; 161 } else { 162 if (!red_is_idling(&q->vars)) 163 red_start_of_idle_period(&q->vars); 164 } 165 return skb; 166 } 167 168 static struct sk_buff *red_peek(struct Qdisc *sch) 169 { 170 struct red_sched_data *q = qdisc_priv(sch); 171 struct Qdisc *child = q->qdisc; 172 173 return child->ops->peek(child); 174 } 175 176 static void red_reset(struct Qdisc *sch) 177 { 178 struct red_sched_data *q = qdisc_priv(sch); 179 180 qdisc_reset(q->qdisc); 181 red_restart(&q->vars); 182 } 183 184 static int red_offload(struct Qdisc *sch, bool enable) 185 { 186 struct red_sched_data *q = qdisc_priv(sch); 187 struct net_device *dev = qdisc_dev(sch); 188 struct tc_red_qopt_offload opt = { 189 .handle = sch->handle, 190 .parent = sch->parent, 191 }; 192 193 if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc) 194 return -EOPNOTSUPP; 195 196 if (enable) { 197 opt.command = TC_RED_REPLACE; 198 opt.set.min = q->parms.qth_min >> q->parms.Wlog; 199 opt.set.max = q->parms.qth_max >> q->parms.Wlog; 200 opt.set.probability = q->parms.max_P; 201 opt.set.limit = q->limit; 202 opt.set.is_ecn = red_use_ecn(q); 203 opt.set.is_harddrop = red_use_harddrop(q); 204 opt.set.is_nodrop = red_use_nodrop(q); 205 opt.set.qstats = &sch->qstats; 206 } else { 207 opt.command = TC_RED_DESTROY; 208 } 209 210 return dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED, &opt); 211 } 212 213 static void red_destroy(struct Qdisc *sch) 214 { 215 struct red_sched_data *q = qdisc_priv(sch); 216 217 tcf_qevent_destroy(&q->qe_mark, sch); 218 tcf_qevent_destroy(&q->qe_early_drop, sch); 219 del_timer_sync(&q->adapt_timer); 220 red_offload(sch, false); 221 qdisc_put(q->qdisc); 222 } 223 224 static const struct nla_policy red_policy[TCA_RED_MAX + 1] = { 225 [TCA_RED_UNSPEC] = { .strict_start_type = TCA_RED_FLAGS }, 226 [TCA_RED_PARMS] = { .len = sizeof(struct tc_red_qopt) }, 227 [TCA_RED_STAB] = { .len = RED_STAB_SIZE }, 228 [TCA_RED_MAX_P] = { .type = NLA_U32 }, 229 [TCA_RED_FLAGS] = NLA_POLICY_BITFIELD32(TC_RED_SUPPORTED_FLAGS), 230 [TCA_RED_EARLY_DROP_BLOCK] = { .type = NLA_U32 }, 231 [TCA_RED_MARK_BLOCK] = { .type = NLA_U32 }, 232 }; 233 234 static int __red_change(struct Qdisc *sch, struct nlattr **tb, 235 struct netlink_ext_ack *extack) 236 { 237 struct Qdisc *old_child = NULL, *child = NULL; 238 struct red_sched_data *q = qdisc_priv(sch); 239 struct nla_bitfield32 flags_bf; 240 struct tc_red_qopt *ctl; 241 unsigned char userbits; 242 unsigned char flags; 243 int err; 244 u32 max_P; 245 u8 *stab; 246 247 if (tb[TCA_RED_PARMS] == NULL || 248 tb[TCA_RED_STAB] == NULL) 249 return -EINVAL; 250 251 max_P = tb[TCA_RED_MAX_P] ? nla_get_u32(tb[TCA_RED_MAX_P]) : 0; 252 253 ctl = nla_data(tb[TCA_RED_PARMS]); 254 stab = nla_data(tb[TCA_RED_STAB]); 255 if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog, 256 ctl->Scell_log, stab)) 257 return -EINVAL; 258 259 err = red_get_flags(ctl->flags, TC_RED_HISTORIC_FLAGS, 260 tb[TCA_RED_FLAGS], TC_RED_SUPPORTED_FLAGS, 261 &flags_bf, &userbits, extack); 262 if (err) 263 return err; 264 265 if (ctl->limit > 0) { 266 child = fifo_create_dflt(sch, &bfifo_qdisc_ops, ctl->limit, 267 extack); 268 if (IS_ERR(child)) 269 return PTR_ERR(child); 270 271 /* child is fifo, no need to check for noop_qdisc */ 272 qdisc_hash_add(child, true); 273 } 274 275 sch_tree_lock(sch); 276 277 flags = (q->flags & ~flags_bf.selector) | flags_bf.value; 278 err = red_validate_flags(flags, extack); 279 if (err) 280 goto unlock_out; 281 282 q->flags = flags; 283 q->userbits = userbits; 284 q->limit = ctl->limit; 285 if (child) { 286 qdisc_tree_flush_backlog(q->qdisc); 287 old_child = q->qdisc; 288 q->qdisc = child; 289 } 290 291 red_set_parms(&q->parms, 292 ctl->qth_min, ctl->qth_max, ctl->Wlog, 293 ctl->Plog, ctl->Scell_log, 294 stab, 295 max_P); 296 red_set_vars(&q->vars); 297 298 del_timer(&q->adapt_timer); 299 if (ctl->flags & TC_RED_ADAPTATIVE) 300 mod_timer(&q->adapt_timer, jiffies + HZ/2); 301 302 if (!q->qdisc->q.qlen) 303 red_start_of_idle_period(&q->vars); 304 305 sch_tree_unlock(sch); 306 307 red_offload(sch, true); 308 309 if (old_child) 310 qdisc_put(old_child); 311 return 0; 312 313 unlock_out: 314 sch_tree_unlock(sch); 315 if (child) 316 qdisc_put(child); 317 return err; 318 } 319 320 static inline void red_adaptative_timer(struct timer_list *t) 321 { 322 struct red_sched_data *q = from_timer(q, t, adapt_timer); 323 struct Qdisc *sch = q->sch; 324 spinlock_t *root_lock = qdisc_lock(qdisc_root_sleeping(sch)); 325 326 spin_lock(root_lock); 327 red_adaptative_algo(&q->parms, &q->vars); 328 mod_timer(&q->adapt_timer, jiffies + HZ/2); 329 spin_unlock(root_lock); 330 } 331 332 static int red_init(struct Qdisc *sch, struct nlattr *opt, 333 struct netlink_ext_ack *extack) 334 { 335 struct red_sched_data *q = qdisc_priv(sch); 336 struct nlattr *tb[TCA_RED_MAX + 1]; 337 int err; 338 339 q->qdisc = &noop_qdisc; 340 q->sch = sch; 341 timer_setup(&q->adapt_timer, red_adaptative_timer, 0); 342 343 if (!opt) 344 return -EINVAL; 345 346 err = nla_parse_nested_deprecated(tb, TCA_RED_MAX, opt, red_policy, 347 extack); 348 if (err < 0) 349 return err; 350 351 err = __red_change(sch, tb, extack); 352 if (err) 353 return err; 354 355 err = tcf_qevent_init(&q->qe_early_drop, sch, 356 FLOW_BLOCK_BINDER_TYPE_RED_EARLY_DROP, 357 tb[TCA_RED_EARLY_DROP_BLOCK], extack); 358 if (err) 359 return err; 360 361 return tcf_qevent_init(&q->qe_mark, sch, 362 FLOW_BLOCK_BINDER_TYPE_RED_MARK, 363 tb[TCA_RED_MARK_BLOCK], extack); 364 } 365 366 static int red_change(struct Qdisc *sch, struct nlattr *opt, 367 struct netlink_ext_ack *extack) 368 { 369 struct red_sched_data *q = qdisc_priv(sch); 370 struct nlattr *tb[TCA_RED_MAX + 1]; 371 int err; 372 373 err = nla_parse_nested_deprecated(tb, TCA_RED_MAX, opt, red_policy, 374 extack); 375 if (err < 0) 376 return err; 377 378 err = tcf_qevent_validate_change(&q->qe_early_drop, 379 tb[TCA_RED_EARLY_DROP_BLOCK], extack); 380 if (err) 381 return err; 382 383 err = tcf_qevent_validate_change(&q->qe_mark, 384 tb[TCA_RED_MARK_BLOCK], extack); 385 if (err) 386 return err; 387 388 return __red_change(sch, tb, extack); 389 } 390 391 static int red_dump_offload_stats(struct Qdisc *sch) 392 { 393 struct tc_red_qopt_offload hw_stats = { 394 .command = TC_RED_STATS, 395 .handle = sch->handle, 396 .parent = sch->parent, 397 { 398 .stats.bstats = &sch->bstats, 399 .stats.qstats = &sch->qstats, 400 }, 401 }; 402 403 return qdisc_offload_dump_helper(sch, TC_SETUP_QDISC_RED, &hw_stats); 404 } 405 406 static int red_dump(struct Qdisc *sch, struct sk_buff *skb) 407 { 408 struct red_sched_data *q = qdisc_priv(sch); 409 struct nlattr *opts = NULL; 410 struct tc_red_qopt opt = { 411 .limit = q->limit, 412 .flags = (q->flags & TC_RED_HISTORIC_FLAGS) | 413 q->userbits, 414 .qth_min = q->parms.qth_min >> q->parms.Wlog, 415 .qth_max = q->parms.qth_max >> q->parms.Wlog, 416 .Wlog = q->parms.Wlog, 417 .Plog = q->parms.Plog, 418 .Scell_log = q->parms.Scell_log, 419 }; 420 int err; 421 422 err = red_dump_offload_stats(sch); 423 if (err) 424 goto nla_put_failure; 425 426 opts = nla_nest_start_noflag(skb, TCA_OPTIONS); 427 if (opts == NULL) 428 goto nla_put_failure; 429 if (nla_put(skb, TCA_RED_PARMS, sizeof(opt), &opt) || 430 nla_put_u32(skb, TCA_RED_MAX_P, q->parms.max_P) || 431 nla_put_bitfield32(skb, TCA_RED_FLAGS, 432 q->flags, TC_RED_SUPPORTED_FLAGS) || 433 tcf_qevent_dump(skb, TCA_RED_MARK_BLOCK, &q->qe_mark) || 434 tcf_qevent_dump(skb, TCA_RED_EARLY_DROP_BLOCK, &q->qe_early_drop)) 435 goto nla_put_failure; 436 return nla_nest_end(skb, opts); 437 438 nla_put_failure: 439 nla_nest_cancel(skb, opts); 440 return -EMSGSIZE; 441 } 442 443 static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d) 444 { 445 struct red_sched_data *q = qdisc_priv(sch); 446 struct net_device *dev = qdisc_dev(sch); 447 struct tc_red_xstats st = {0}; 448 449 if (sch->flags & TCQ_F_OFFLOADED) { 450 struct tc_red_qopt_offload hw_stats_request = { 451 .command = TC_RED_XSTATS, 452 .handle = sch->handle, 453 .parent = sch->parent, 454 { 455 .xstats = &q->stats, 456 }, 457 }; 458 dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED, 459 &hw_stats_request); 460 } 461 st.early = q->stats.prob_drop + q->stats.forced_drop; 462 st.pdrop = q->stats.pdrop; 463 st.marked = q->stats.prob_mark + q->stats.forced_mark; 464 465 return gnet_stats_copy_app(d, &st, sizeof(st)); 466 } 467 468 static int red_dump_class(struct Qdisc *sch, unsigned long cl, 469 struct sk_buff *skb, struct tcmsg *tcm) 470 { 471 struct red_sched_data *q = qdisc_priv(sch); 472 473 tcm->tcm_handle |= TC_H_MIN(1); 474 tcm->tcm_info = q->qdisc->handle; 475 return 0; 476 } 477 478 static void red_graft_offload(struct Qdisc *sch, 479 struct Qdisc *new, struct Qdisc *old, 480 struct netlink_ext_ack *extack) 481 { 482 struct tc_red_qopt_offload graft_offload = { 483 .handle = sch->handle, 484 .parent = sch->parent, 485 .child_handle = new->handle, 486 .command = TC_RED_GRAFT, 487 }; 488 489 qdisc_offload_graft_helper(qdisc_dev(sch), sch, new, old, 490 TC_SETUP_QDISC_RED, &graft_offload, extack); 491 } 492 493 static int red_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, 494 struct Qdisc **old, struct netlink_ext_ack *extack) 495 { 496 struct red_sched_data *q = qdisc_priv(sch); 497 498 if (new == NULL) 499 new = &noop_qdisc; 500 501 *old = qdisc_replace(sch, new, &q->qdisc); 502 503 red_graft_offload(sch, new, *old, extack); 504 return 0; 505 } 506 507 static struct Qdisc *red_leaf(struct Qdisc *sch, unsigned long arg) 508 { 509 struct red_sched_data *q = qdisc_priv(sch); 510 return q->qdisc; 511 } 512 513 static unsigned long red_find(struct Qdisc *sch, u32 classid) 514 { 515 return 1; 516 } 517 518 static void red_walk(struct Qdisc *sch, struct qdisc_walker *walker) 519 { 520 if (!walker->stop) { 521 tc_qdisc_stats_dump(sch, 1, walker); 522 } 523 } 524 525 static const struct Qdisc_class_ops red_class_ops = { 526 .graft = red_graft, 527 .leaf = red_leaf, 528 .find = red_find, 529 .walk = red_walk, 530 .dump = red_dump_class, 531 }; 532 533 static struct Qdisc_ops red_qdisc_ops __read_mostly = { 534 .id = "red", 535 .priv_size = sizeof(struct red_sched_data), 536 .cl_ops = &red_class_ops, 537 .enqueue = red_enqueue, 538 .dequeue = red_dequeue, 539 .peek = red_peek, 540 .init = red_init, 541 .reset = red_reset, 542 .destroy = red_destroy, 543 .change = red_change, 544 .dump = red_dump, 545 .dump_stats = red_dump_stats, 546 .owner = THIS_MODULE, 547 }; 548 549 static int __init red_module_init(void) 550 { 551 return register_qdisc(&red_qdisc_ops); 552 } 553 554 static void __exit red_module_exit(void) 555 { 556 unregister_qdisc(&red_qdisc_ops); 557 } 558 559 module_init(red_module_init) 560 module_exit(red_module_exit) 561 562 MODULE_LICENSE("GPL"); 563