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 }; 50 51 static const u32 red_supported_flags = TC_RED_HISTORIC_FLAGS | TC_RED_NODROP; 52 53 static inline int red_use_ecn(struct red_sched_data *q) 54 { 55 return q->flags & TC_RED_ECN; 56 } 57 58 static inline int red_use_harddrop(struct red_sched_data *q) 59 { 60 return q->flags & TC_RED_HARDDROP; 61 } 62 63 static int red_use_nodrop(struct red_sched_data *q) 64 { 65 return q->flags & TC_RED_NODROP; 66 } 67 68 static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch, 69 struct sk_buff **to_free) 70 { 71 struct red_sched_data *q = qdisc_priv(sch); 72 struct Qdisc *child = q->qdisc; 73 int ret; 74 75 q->vars.qavg = red_calc_qavg(&q->parms, 76 &q->vars, 77 child->qstats.backlog); 78 79 if (red_is_idling(&q->vars)) 80 red_end_of_idle_period(&q->vars); 81 82 switch (red_action(&q->parms, &q->vars, q->vars.qavg)) { 83 case RED_DONT_MARK: 84 break; 85 86 case RED_PROB_MARK: 87 qdisc_qstats_overlimit(sch); 88 if (!red_use_ecn(q)) { 89 q->stats.prob_drop++; 90 goto congestion_drop; 91 } 92 93 if (INET_ECN_set_ce(skb)) { 94 q->stats.prob_mark++; 95 } else if (!red_use_nodrop(q)) { 96 q->stats.prob_drop++; 97 goto congestion_drop; 98 } 99 100 /* Non-ECT packet in ECN nodrop mode: queue it. */ 101 break; 102 103 case RED_HARD_MARK: 104 qdisc_qstats_overlimit(sch); 105 if (red_use_harddrop(q) || !red_use_ecn(q)) { 106 q->stats.forced_drop++; 107 goto congestion_drop; 108 } 109 110 if (INET_ECN_set_ce(skb)) { 111 q->stats.forced_mark++; 112 } else if (!red_use_nodrop(q)) { 113 q->stats.forced_drop++; 114 goto congestion_drop; 115 } 116 117 /* Non-ECT packet in ECN nodrop mode: queue it. */ 118 break; 119 } 120 121 ret = qdisc_enqueue(skb, child, to_free); 122 if (likely(ret == NET_XMIT_SUCCESS)) { 123 qdisc_qstats_backlog_inc(sch, skb); 124 sch->q.qlen++; 125 } else if (net_xmit_drop_count(ret)) { 126 q->stats.pdrop++; 127 qdisc_qstats_drop(sch); 128 } 129 return ret; 130 131 congestion_drop: 132 qdisc_drop(skb, sch, to_free); 133 return NET_XMIT_CN; 134 } 135 136 static struct sk_buff *red_dequeue(struct Qdisc *sch) 137 { 138 struct sk_buff *skb; 139 struct red_sched_data *q = qdisc_priv(sch); 140 struct Qdisc *child = q->qdisc; 141 142 skb = child->dequeue(child); 143 if (skb) { 144 qdisc_bstats_update(sch, skb); 145 qdisc_qstats_backlog_dec(sch, skb); 146 sch->q.qlen--; 147 } else { 148 if (!red_is_idling(&q->vars)) 149 red_start_of_idle_period(&q->vars); 150 } 151 return skb; 152 } 153 154 static struct sk_buff *red_peek(struct Qdisc *sch) 155 { 156 struct red_sched_data *q = qdisc_priv(sch); 157 struct Qdisc *child = q->qdisc; 158 159 return child->ops->peek(child); 160 } 161 162 static void red_reset(struct Qdisc *sch) 163 { 164 struct red_sched_data *q = qdisc_priv(sch); 165 166 qdisc_reset(q->qdisc); 167 sch->qstats.backlog = 0; 168 sch->q.qlen = 0; 169 red_restart(&q->vars); 170 } 171 172 static int red_offload(struct Qdisc *sch, bool enable) 173 { 174 struct red_sched_data *q = qdisc_priv(sch); 175 struct net_device *dev = qdisc_dev(sch); 176 struct tc_red_qopt_offload opt = { 177 .handle = sch->handle, 178 .parent = sch->parent, 179 }; 180 181 if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc) 182 return -EOPNOTSUPP; 183 184 if (enable) { 185 opt.command = TC_RED_REPLACE; 186 opt.set.min = q->parms.qth_min >> q->parms.Wlog; 187 opt.set.max = q->parms.qth_max >> q->parms.Wlog; 188 opt.set.probability = q->parms.max_P; 189 opt.set.limit = q->limit; 190 opt.set.is_ecn = red_use_ecn(q); 191 opt.set.is_harddrop = red_use_harddrop(q); 192 opt.set.is_nodrop = red_use_nodrop(q); 193 opt.set.qstats = &sch->qstats; 194 } else { 195 opt.command = TC_RED_DESTROY; 196 } 197 198 return dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED, &opt); 199 } 200 201 static void red_destroy(struct Qdisc *sch) 202 { 203 struct red_sched_data *q = qdisc_priv(sch); 204 205 del_timer_sync(&q->adapt_timer); 206 red_offload(sch, false); 207 qdisc_put(q->qdisc); 208 } 209 210 static const struct nla_policy red_policy[TCA_RED_MAX + 1] = { 211 [TCA_RED_UNSPEC] = { .strict_start_type = TCA_RED_FLAGS }, 212 [TCA_RED_PARMS] = { .len = sizeof(struct tc_red_qopt) }, 213 [TCA_RED_STAB] = { .len = RED_STAB_SIZE }, 214 [TCA_RED_MAX_P] = { .type = NLA_U32 }, 215 [TCA_RED_FLAGS] = { .type = NLA_BITFIELD32, 216 .validation_data = &red_supported_flags }, 217 }; 218 219 static int red_change(struct Qdisc *sch, struct nlattr *opt, 220 struct netlink_ext_ack *extack) 221 { 222 struct Qdisc *old_child = NULL, *child = NULL; 223 struct red_sched_data *q = qdisc_priv(sch); 224 struct nlattr *tb[TCA_RED_MAX + 1]; 225 struct nla_bitfield32 flags_bf; 226 struct tc_red_qopt *ctl; 227 unsigned char userbits; 228 unsigned char flags; 229 int err; 230 u32 max_P; 231 232 if (opt == NULL) 233 return -EINVAL; 234 235 err = nla_parse_nested_deprecated(tb, TCA_RED_MAX, opt, red_policy, 236 NULL); 237 if (err < 0) 238 return err; 239 240 if (tb[TCA_RED_PARMS] == NULL || 241 tb[TCA_RED_STAB] == NULL) 242 return -EINVAL; 243 244 max_P = tb[TCA_RED_MAX_P] ? nla_get_u32(tb[TCA_RED_MAX_P]) : 0; 245 246 ctl = nla_data(tb[TCA_RED_PARMS]); 247 if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog)) 248 return -EINVAL; 249 250 err = red_get_flags(ctl->flags, TC_RED_HISTORIC_FLAGS, 251 tb[TCA_RED_FLAGS], red_supported_flags, 252 &flags_bf, &userbits, extack); 253 if (err) 254 return err; 255 256 if (ctl->limit > 0) { 257 child = fifo_create_dflt(sch, &bfifo_qdisc_ops, ctl->limit, 258 extack); 259 if (IS_ERR(child)) 260 return PTR_ERR(child); 261 262 /* child is fifo, no need to check for noop_qdisc */ 263 qdisc_hash_add(child, true); 264 } 265 266 sch_tree_lock(sch); 267 268 flags = (q->flags & ~flags_bf.selector) | flags_bf.value; 269 err = red_validate_flags(flags, extack); 270 if (err) 271 goto unlock_out; 272 273 q->flags = flags; 274 q->userbits = userbits; 275 q->limit = ctl->limit; 276 if (child) { 277 qdisc_tree_flush_backlog(q->qdisc); 278 old_child = q->qdisc; 279 q->qdisc = child; 280 } 281 282 red_set_parms(&q->parms, 283 ctl->qth_min, ctl->qth_max, ctl->Wlog, 284 ctl->Plog, ctl->Scell_log, 285 nla_data(tb[TCA_RED_STAB]), 286 max_P); 287 red_set_vars(&q->vars); 288 289 del_timer(&q->adapt_timer); 290 if (ctl->flags & TC_RED_ADAPTATIVE) 291 mod_timer(&q->adapt_timer, jiffies + HZ/2); 292 293 if (!q->qdisc->q.qlen) 294 red_start_of_idle_period(&q->vars); 295 296 sch_tree_unlock(sch); 297 298 red_offload(sch, true); 299 300 if (old_child) 301 qdisc_put(old_child); 302 return 0; 303 304 unlock_out: 305 sch_tree_unlock(sch); 306 if (child) 307 qdisc_put(child); 308 return err; 309 } 310 311 static inline void red_adaptative_timer(struct timer_list *t) 312 { 313 struct red_sched_data *q = from_timer(q, t, adapt_timer); 314 struct Qdisc *sch = q->sch; 315 spinlock_t *root_lock = qdisc_lock(qdisc_root_sleeping(sch)); 316 317 spin_lock(root_lock); 318 red_adaptative_algo(&q->parms, &q->vars); 319 mod_timer(&q->adapt_timer, jiffies + HZ/2); 320 spin_unlock(root_lock); 321 } 322 323 static int red_init(struct Qdisc *sch, struct nlattr *opt, 324 struct netlink_ext_ack *extack) 325 { 326 struct red_sched_data *q = qdisc_priv(sch); 327 328 q->qdisc = &noop_qdisc; 329 q->sch = sch; 330 timer_setup(&q->adapt_timer, red_adaptative_timer, 0); 331 return red_change(sch, opt, extack); 332 } 333 334 static int red_dump_offload_stats(struct Qdisc *sch) 335 { 336 struct tc_red_qopt_offload hw_stats = { 337 .command = TC_RED_STATS, 338 .handle = sch->handle, 339 .parent = sch->parent, 340 { 341 .stats.bstats = &sch->bstats, 342 .stats.qstats = &sch->qstats, 343 }, 344 }; 345 346 return qdisc_offload_dump_helper(sch, TC_SETUP_QDISC_RED, &hw_stats); 347 } 348 349 static int red_dump(struct Qdisc *sch, struct sk_buff *skb) 350 { 351 struct red_sched_data *q = qdisc_priv(sch); 352 struct nlattr *opts = NULL; 353 struct tc_red_qopt opt = { 354 .limit = q->limit, 355 .flags = (q->flags & TC_RED_HISTORIC_FLAGS) | 356 q->userbits, 357 .qth_min = q->parms.qth_min >> q->parms.Wlog, 358 .qth_max = q->parms.qth_max >> q->parms.Wlog, 359 .Wlog = q->parms.Wlog, 360 .Plog = q->parms.Plog, 361 .Scell_log = q->parms.Scell_log, 362 }; 363 int err; 364 365 err = red_dump_offload_stats(sch); 366 if (err) 367 goto nla_put_failure; 368 369 opts = nla_nest_start_noflag(skb, TCA_OPTIONS); 370 if (opts == NULL) 371 goto nla_put_failure; 372 if (nla_put(skb, TCA_RED_PARMS, sizeof(opt), &opt) || 373 nla_put_u32(skb, TCA_RED_MAX_P, q->parms.max_P) || 374 nla_put_bitfield32(skb, TCA_RED_FLAGS, 375 q->flags, red_supported_flags)) 376 goto nla_put_failure; 377 return nla_nest_end(skb, opts); 378 379 nla_put_failure: 380 nla_nest_cancel(skb, opts); 381 return -EMSGSIZE; 382 } 383 384 static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d) 385 { 386 struct red_sched_data *q = qdisc_priv(sch); 387 struct net_device *dev = qdisc_dev(sch); 388 struct tc_red_xstats st = {0}; 389 390 if (sch->flags & TCQ_F_OFFLOADED) { 391 struct tc_red_qopt_offload hw_stats_request = { 392 .command = TC_RED_XSTATS, 393 .handle = sch->handle, 394 .parent = sch->parent, 395 { 396 .xstats = &q->stats, 397 }, 398 }; 399 dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED, 400 &hw_stats_request); 401 } 402 st.early = q->stats.prob_drop + q->stats.forced_drop; 403 st.pdrop = q->stats.pdrop; 404 st.other = q->stats.other; 405 st.marked = q->stats.prob_mark + q->stats.forced_mark; 406 407 return gnet_stats_copy_app(d, &st, sizeof(st)); 408 } 409 410 static int red_dump_class(struct Qdisc *sch, unsigned long cl, 411 struct sk_buff *skb, struct tcmsg *tcm) 412 { 413 struct red_sched_data *q = qdisc_priv(sch); 414 415 tcm->tcm_handle |= TC_H_MIN(1); 416 tcm->tcm_info = q->qdisc->handle; 417 return 0; 418 } 419 420 static void red_graft_offload(struct Qdisc *sch, 421 struct Qdisc *new, struct Qdisc *old, 422 struct netlink_ext_ack *extack) 423 { 424 struct tc_red_qopt_offload graft_offload = { 425 .handle = sch->handle, 426 .parent = sch->parent, 427 .child_handle = new->handle, 428 .command = TC_RED_GRAFT, 429 }; 430 431 qdisc_offload_graft_helper(qdisc_dev(sch), sch, new, old, 432 TC_SETUP_QDISC_RED, &graft_offload, extack); 433 } 434 435 static int red_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, 436 struct Qdisc **old, struct netlink_ext_ack *extack) 437 { 438 struct red_sched_data *q = qdisc_priv(sch); 439 440 if (new == NULL) 441 new = &noop_qdisc; 442 443 *old = qdisc_replace(sch, new, &q->qdisc); 444 445 red_graft_offload(sch, new, *old, extack); 446 return 0; 447 } 448 449 static struct Qdisc *red_leaf(struct Qdisc *sch, unsigned long arg) 450 { 451 struct red_sched_data *q = qdisc_priv(sch); 452 return q->qdisc; 453 } 454 455 static unsigned long red_find(struct Qdisc *sch, u32 classid) 456 { 457 return 1; 458 } 459 460 static void red_walk(struct Qdisc *sch, struct qdisc_walker *walker) 461 { 462 if (!walker->stop) { 463 if (walker->count >= walker->skip) 464 if (walker->fn(sch, 1, walker) < 0) { 465 walker->stop = 1; 466 return; 467 } 468 walker->count++; 469 } 470 } 471 472 static const struct Qdisc_class_ops red_class_ops = { 473 .graft = red_graft, 474 .leaf = red_leaf, 475 .find = red_find, 476 .walk = red_walk, 477 .dump = red_dump_class, 478 }; 479 480 static struct Qdisc_ops red_qdisc_ops __read_mostly = { 481 .id = "red", 482 .priv_size = sizeof(struct red_sched_data), 483 .cl_ops = &red_class_ops, 484 .enqueue = red_enqueue, 485 .dequeue = red_dequeue, 486 .peek = red_peek, 487 .init = red_init, 488 .reset = red_reset, 489 .destroy = red_destroy, 490 .change = red_change, 491 .dump = red_dump, 492 .dump_stats = red_dump_stats, 493 .owner = THIS_MODULE, 494 }; 495 496 static int __init red_module_init(void) 497 { 498 return register_qdisc(&red_qdisc_ops); 499 } 500 501 static void __exit red_module_exit(void) 502 { 503 unregister_qdisc(&red_qdisc_ops); 504 } 505 506 module_init(red_module_init) 507 module_exit(red_module_exit) 508 509 MODULE_LICENSE("GPL"); 510