1 /* 2 * net/sched/sch_red.c Random Early Detection queue. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 7 * 2 of the License, or (at your option) any later version. 8 * 9 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> 10 * 11 * Changes: 12 * J Hadi Salim 980914: computation fixes 13 * Alexey Makarenko <makar@phoenix.kharkov.ua> 990814: qave on idle link was calculated incorrectly. 14 * J Hadi Salim 980816: ECN support 15 */ 16 17 #include <linux/module.h> 18 #include <linux/types.h> 19 #include <linux/kernel.h> 20 #include <linux/skbuff.h> 21 #include <net/pkt_sched.h> 22 #include <net/pkt_cls.h> 23 #include <net/inet_ecn.h> 24 #include <net/red.h> 25 26 27 /* Parameters, settable by user: 28 ----------------------------- 29 30 limit - bytes (must be > qth_max + burst) 31 32 Hard limit on queue length, should be chosen >qth_max 33 to allow packet bursts. This parameter does not 34 affect the algorithms behaviour and can be chosen 35 arbitrarily high (well, less than ram size) 36 Really, this limit will never be reached 37 if RED works correctly. 38 */ 39 40 struct red_sched_data { 41 u32 limit; /* HARD maximal queue length */ 42 unsigned char flags; 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 inline int red_use_ecn(struct red_sched_data *q) 52 { 53 return q->flags & TC_RED_ECN; 54 } 55 56 static inline int red_use_harddrop(struct red_sched_data *q) 57 { 58 return q->flags & TC_RED_HARDDROP; 59 } 60 61 static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch, 62 struct sk_buff **to_free) 63 { 64 struct red_sched_data *q = qdisc_priv(sch); 65 struct Qdisc *child = q->qdisc; 66 int ret; 67 68 q->vars.qavg = red_calc_qavg(&q->parms, 69 &q->vars, 70 child->qstats.backlog); 71 72 if (red_is_idling(&q->vars)) 73 red_end_of_idle_period(&q->vars); 74 75 switch (red_action(&q->parms, &q->vars, q->vars.qavg)) { 76 case RED_DONT_MARK: 77 break; 78 79 case RED_PROB_MARK: 80 qdisc_qstats_overlimit(sch); 81 if (!red_use_ecn(q) || !INET_ECN_set_ce(skb)) { 82 q->stats.prob_drop++; 83 goto congestion_drop; 84 } 85 86 q->stats.prob_mark++; 87 break; 88 89 case RED_HARD_MARK: 90 qdisc_qstats_overlimit(sch); 91 if (red_use_harddrop(q) || !red_use_ecn(q) || 92 !INET_ECN_set_ce(skb)) { 93 q->stats.forced_drop++; 94 goto congestion_drop; 95 } 96 97 q->stats.forced_mark++; 98 break; 99 } 100 101 ret = qdisc_enqueue(skb, child, to_free); 102 if (likely(ret == NET_XMIT_SUCCESS)) { 103 qdisc_qstats_backlog_inc(sch, skb); 104 sch->q.qlen++; 105 } else if (net_xmit_drop_count(ret)) { 106 q->stats.pdrop++; 107 qdisc_qstats_drop(sch); 108 } 109 return ret; 110 111 congestion_drop: 112 qdisc_drop(skb, sch, to_free); 113 return NET_XMIT_CN; 114 } 115 116 static struct sk_buff *red_dequeue(struct Qdisc *sch) 117 { 118 struct sk_buff *skb; 119 struct red_sched_data *q = qdisc_priv(sch); 120 struct Qdisc *child = q->qdisc; 121 122 skb = child->dequeue(child); 123 if (skb) { 124 qdisc_bstats_update(sch, skb); 125 qdisc_qstats_backlog_dec(sch, skb); 126 sch->q.qlen--; 127 } else { 128 if (!red_is_idling(&q->vars)) 129 red_start_of_idle_period(&q->vars); 130 } 131 return skb; 132 } 133 134 static struct sk_buff *red_peek(struct Qdisc *sch) 135 { 136 struct red_sched_data *q = qdisc_priv(sch); 137 struct Qdisc *child = q->qdisc; 138 139 return child->ops->peek(child); 140 } 141 142 static void red_reset(struct Qdisc *sch) 143 { 144 struct red_sched_data *q = qdisc_priv(sch); 145 146 qdisc_reset(q->qdisc); 147 sch->qstats.backlog = 0; 148 sch->q.qlen = 0; 149 red_restart(&q->vars); 150 } 151 152 static int red_offload(struct Qdisc *sch, bool enable) 153 { 154 struct red_sched_data *q = qdisc_priv(sch); 155 struct net_device *dev = qdisc_dev(sch); 156 struct tc_red_qopt_offload opt = { 157 .handle = sch->handle, 158 .parent = sch->parent, 159 }; 160 161 if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc) 162 return -EOPNOTSUPP; 163 164 if (enable) { 165 opt.command = TC_RED_REPLACE; 166 opt.set.min = q->parms.qth_min >> q->parms.Wlog; 167 opt.set.max = q->parms.qth_max >> q->parms.Wlog; 168 opt.set.probability = q->parms.max_P; 169 opt.set.is_ecn = red_use_ecn(q); 170 } else { 171 opt.command = TC_RED_DESTROY; 172 } 173 174 return dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED, &opt); 175 } 176 177 static void red_destroy(struct Qdisc *sch) 178 { 179 struct red_sched_data *q = qdisc_priv(sch); 180 181 del_timer_sync(&q->adapt_timer); 182 red_offload(sch, false); 183 qdisc_destroy(q->qdisc); 184 } 185 186 static const struct nla_policy red_policy[TCA_RED_MAX + 1] = { 187 [TCA_RED_PARMS] = { .len = sizeof(struct tc_red_qopt) }, 188 [TCA_RED_STAB] = { .len = RED_STAB_SIZE }, 189 [TCA_RED_MAX_P] = { .type = NLA_U32 }, 190 }; 191 192 static int red_change(struct Qdisc *sch, struct nlattr *opt) 193 { 194 struct red_sched_data *q = qdisc_priv(sch); 195 struct nlattr *tb[TCA_RED_MAX + 1]; 196 struct tc_red_qopt *ctl; 197 struct Qdisc *child = NULL; 198 int err; 199 u32 max_P; 200 201 if (opt == NULL) 202 return -EINVAL; 203 204 err = nla_parse_nested(tb, TCA_RED_MAX, opt, red_policy, NULL); 205 if (err < 0) 206 return err; 207 208 if (tb[TCA_RED_PARMS] == NULL || 209 tb[TCA_RED_STAB] == NULL) 210 return -EINVAL; 211 212 max_P = tb[TCA_RED_MAX_P] ? nla_get_u32(tb[TCA_RED_MAX_P]) : 0; 213 214 ctl = nla_data(tb[TCA_RED_PARMS]); 215 216 if (ctl->limit > 0) { 217 child = fifo_create_dflt(sch, &bfifo_qdisc_ops, ctl->limit); 218 if (IS_ERR(child)) 219 return PTR_ERR(child); 220 } 221 222 if (child != &noop_qdisc) 223 qdisc_hash_add(child, true); 224 sch_tree_lock(sch); 225 q->flags = ctl->flags; 226 q->limit = ctl->limit; 227 if (child) { 228 qdisc_tree_reduce_backlog(q->qdisc, q->qdisc->q.qlen, 229 q->qdisc->qstats.backlog); 230 qdisc_destroy(q->qdisc); 231 q->qdisc = child; 232 } 233 234 red_set_parms(&q->parms, 235 ctl->qth_min, ctl->qth_max, ctl->Wlog, 236 ctl->Plog, ctl->Scell_log, 237 nla_data(tb[TCA_RED_STAB]), 238 max_P); 239 red_set_vars(&q->vars); 240 241 del_timer(&q->adapt_timer); 242 if (ctl->flags & TC_RED_ADAPTATIVE) 243 mod_timer(&q->adapt_timer, jiffies + HZ/2); 244 245 if (!q->qdisc->q.qlen) 246 red_start_of_idle_period(&q->vars); 247 248 sch_tree_unlock(sch); 249 red_offload(sch, true); 250 return 0; 251 } 252 253 static inline void red_adaptative_timer(struct timer_list *t) 254 { 255 struct red_sched_data *q = from_timer(q, t, adapt_timer); 256 struct Qdisc *sch = q->sch; 257 spinlock_t *root_lock = qdisc_lock(qdisc_root_sleeping(sch)); 258 259 spin_lock(root_lock); 260 red_adaptative_algo(&q->parms, &q->vars); 261 mod_timer(&q->adapt_timer, jiffies + HZ/2); 262 spin_unlock(root_lock); 263 } 264 265 static int red_init(struct Qdisc *sch, struct nlattr *opt) 266 { 267 struct red_sched_data *q = qdisc_priv(sch); 268 269 q->qdisc = &noop_qdisc; 270 q->sch = sch; 271 timer_setup(&q->adapt_timer, red_adaptative_timer, 0); 272 return red_change(sch, opt); 273 } 274 275 static int red_dump_offload(struct Qdisc *sch, struct tc_red_qopt *opt) 276 { 277 struct net_device *dev = qdisc_dev(sch); 278 struct tc_red_qopt_offload hw_stats = { 279 .handle = sch->handle, 280 .parent = sch->parent, 281 .command = TC_RED_STATS, 282 .stats.bstats = &sch->bstats, 283 .stats.qstats = &sch->qstats, 284 }; 285 int err; 286 287 opt->flags &= ~TC_RED_OFFLOADED; 288 if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc) 289 return 0; 290 291 err = dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED, 292 &hw_stats); 293 if (err == -EOPNOTSUPP) 294 return 0; 295 296 if (!err) 297 opt->flags |= TC_RED_OFFLOADED; 298 299 return err; 300 } 301 302 static int red_dump(struct Qdisc *sch, struct sk_buff *skb) 303 { 304 struct red_sched_data *q = qdisc_priv(sch); 305 struct nlattr *opts = NULL; 306 struct tc_red_qopt opt = { 307 .limit = q->limit, 308 .flags = q->flags, 309 .qth_min = q->parms.qth_min >> q->parms.Wlog, 310 .qth_max = q->parms.qth_max >> q->parms.Wlog, 311 .Wlog = q->parms.Wlog, 312 .Plog = q->parms.Plog, 313 .Scell_log = q->parms.Scell_log, 314 }; 315 int err; 316 317 sch->qstats.backlog = q->qdisc->qstats.backlog; 318 err = red_dump_offload(sch, &opt); 319 if (err) 320 goto nla_put_failure; 321 322 opts = nla_nest_start(skb, TCA_OPTIONS); 323 if (opts == NULL) 324 goto nla_put_failure; 325 if (nla_put(skb, TCA_RED_PARMS, sizeof(opt), &opt) || 326 nla_put_u32(skb, TCA_RED_MAX_P, q->parms.max_P)) 327 goto nla_put_failure; 328 return nla_nest_end(skb, opts); 329 330 nla_put_failure: 331 nla_nest_cancel(skb, opts); 332 return -EMSGSIZE; 333 } 334 335 static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d) 336 { 337 struct red_sched_data *q = qdisc_priv(sch); 338 struct net_device *dev = qdisc_dev(sch); 339 struct tc_red_xstats st = { 340 .early = q->stats.prob_drop + q->stats.forced_drop, 341 .pdrop = q->stats.pdrop, 342 .other = q->stats.other, 343 .marked = q->stats.prob_mark + q->stats.forced_mark, 344 }; 345 346 if (tc_can_offload(dev) && dev->netdev_ops->ndo_setup_tc) { 347 struct red_stats hw_stats = {0}; 348 struct tc_red_qopt_offload hw_stats_request = { 349 .handle = sch->handle, 350 .parent = sch->parent, 351 .command = TC_RED_XSTATS, 352 .xstats = &hw_stats, 353 }; 354 if (!dev->netdev_ops->ndo_setup_tc(dev, 355 TC_SETUP_QDISC_RED, 356 &hw_stats_request)) { 357 st.early += hw_stats.prob_drop + hw_stats.forced_drop; 358 st.pdrop += hw_stats.pdrop; 359 st.other += hw_stats.other; 360 st.marked += hw_stats.prob_mark + hw_stats.forced_mark; 361 } 362 } 363 364 return gnet_stats_copy_app(d, &st, sizeof(st)); 365 } 366 367 static int red_dump_class(struct Qdisc *sch, unsigned long cl, 368 struct sk_buff *skb, struct tcmsg *tcm) 369 { 370 struct red_sched_data *q = qdisc_priv(sch); 371 372 tcm->tcm_handle |= TC_H_MIN(1); 373 tcm->tcm_info = q->qdisc->handle; 374 return 0; 375 } 376 377 static int red_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, 378 struct Qdisc **old) 379 { 380 struct red_sched_data *q = qdisc_priv(sch); 381 382 if (new == NULL) 383 new = &noop_qdisc; 384 385 *old = qdisc_replace(sch, new, &q->qdisc); 386 return 0; 387 } 388 389 static struct Qdisc *red_leaf(struct Qdisc *sch, unsigned long arg) 390 { 391 struct red_sched_data *q = qdisc_priv(sch); 392 return q->qdisc; 393 } 394 395 static unsigned long red_find(struct Qdisc *sch, u32 classid) 396 { 397 return 1; 398 } 399 400 static void red_walk(struct Qdisc *sch, struct qdisc_walker *walker) 401 { 402 if (!walker->stop) { 403 if (walker->count >= walker->skip) 404 if (walker->fn(sch, 1, walker) < 0) { 405 walker->stop = 1; 406 return; 407 } 408 walker->count++; 409 } 410 } 411 412 static const struct Qdisc_class_ops red_class_ops = { 413 .graft = red_graft, 414 .leaf = red_leaf, 415 .find = red_find, 416 .walk = red_walk, 417 .dump = red_dump_class, 418 }; 419 420 static struct Qdisc_ops red_qdisc_ops __read_mostly = { 421 .id = "red", 422 .priv_size = sizeof(struct red_sched_data), 423 .cl_ops = &red_class_ops, 424 .enqueue = red_enqueue, 425 .dequeue = red_dequeue, 426 .peek = red_peek, 427 .init = red_init, 428 .reset = red_reset, 429 .destroy = red_destroy, 430 .change = red_change, 431 .dump = red_dump, 432 .dump_stats = red_dump_stats, 433 .owner = THIS_MODULE, 434 }; 435 436 static int __init red_module_init(void) 437 { 438 return register_qdisc(&red_qdisc_ops); 439 } 440 441 static void __exit red_module_exit(void) 442 { 443 unregister_qdisc(&red_qdisc_ops); 444 } 445 446 module_init(red_module_init) 447 module_exit(red_module_exit) 448 449 MODULE_LICENSE("GPL"); 450