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 opt.set.qstats = &sch->qstats; 171 } else { 172 opt.command = TC_RED_DESTROY; 173 } 174 175 return dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED, &opt); 176 } 177 178 static void red_destroy(struct Qdisc *sch) 179 { 180 struct red_sched_data *q = qdisc_priv(sch); 181 182 del_timer_sync(&q->adapt_timer); 183 red_offload(sch, false); 184 qdisc_destroy(q->qdisc); 185 } 186 187 static const struct nla_policy red_policy[TCA_RED_MAX + 1] = { 188 [TCA_RED_PARMS] = { .len = sizeof(struct tc_red_qopt) }, 189 [TCA_RED_STAB] = { .len = RED_STAB_SIZE }, 190 [TCA_RED_MAX_P] = { .type = NLA_U32 }, 191 }; 192 193 static int red_change(struct Qdisc *sch, struct nlattr *opt, 194 struct netlink_ext_ack *extack) 195 { 196 struct red_sched_data *q = qdisc_priv(sch); 197 struct nlattr *tb[TCA_RED_MAX + 1]; 198 struct tc_red_qopt *ctl; 199 struct Qdisc *child = NULL; 200 int err; 201 u32 max_P; 202 203 if (opt == NULL) 204 return -EINVAL; 205 206 err = nla_parse_nested(tb, TCA_RED_MAX, opt, red_policy, NULL); 207 if (err < 0) 208 return err; 209 210 if (tb[TCA_RED_PARMS] == NULL || 211 tb[TCA_RED_STAB] == NULL) 212 return -EINVAL; 213 214 max_P = tb[TCA_RED_MAX_P] ? nla_get_u32(tb[TCA_RED_MAX_P]) : 0; 215 216 ctl = nla_data(tb[TCA_RED_PARMS]); 217 if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog)) 218 return -EINVAL; 219 220 if (ctl->limit > 0) { 221 child = fifo_create_dflt(sch, &bfifo_qdisc_ops, ctl->limit, 222 extack); 223 if (IS_ERR(child)) 224 return PTR_ERR(child); 225 } 226 227 if (child != &noop_qdisc) 228 qdisc_hash_add(child, true); 229 sch_tree_lock(sch); 230 q->flags = ctl->flags; 231 q->limit = ctl->limit; 232 if (child) { 233 qdisc_tree_reduce_backlog(q->qdisc, q->qdisc->q.qlen, 234 q->qdisc->qstats.backlog); 235 qdisc_destroy(q->qdisc); 236 q->qdisc = child; 237 } 238 239 red_set_parms(&q->parms, 240 ctl->qth_min, ctl->qth_max, ctl->Wlog, 241 ctl->Plog, ctl->Scell_log, 242 nla_data(tb[TCA_RED_STAB]), 243 max_P); 244 red_set_vars(&q->vars); 245 246 del_timer(&q->adapt_timer); 247 if (ctl->flags & TC_RED_ADAPTATIVE) 248 mod_timer(&q->adapt_timer, jiffies + HZ/2); 249 250 if (!q->qdisc->q.qlen) 251 red_start_of_idle_period(&q->vars); 252 253 sch_tree_unlock(sch); 254 red_offload(sch, true); 255 return 0; 256 } 257 258 static inline void red_adaptative_timer(struct timer_list *t) 259 { 260 struct red_sched_data *q = from_timer(q, t, adapt_timer); 261 struct Qdisc *sch = q->sch; 262 spinlock_t *root_lock = qdisc_lock(qdisc_root_sleeping(sch)); 263 264 spin_lock(root_lock); 265 red_adaptative_algo(&q->parms, &q->vars); 266 mod_timer(&q->adapt_timer, jiffies + HZ/2); 267 spin_unlock(root_lock); 268 } 269 270 static int red_init(struct Qdisc *sch, struct nlattr *opt, 271 struct netlink_ext_ack *extack) 272 { 273 struct red_sched_data *q = qdisc_priv(sch); 274 275 q->qdisc = &noop_qdisc; 276 q->sch = sch; 277 timer_setup(&q->adapt_timer, red_adaptative_timer, 0); 278 return red_change(sch, opt, extack); 279 } 280 281 static int red_dump_offload_stats(struct Qdisc *sch, struct tc_red_qopt *opt) 282 { 283 struct net_device *dev = qdisc_dev(sch); 284 struct tc_red_qopt_offload hw_stats = { 285 .command = TC_RED_STATS, 286 .handle = sch->handle, 287 .parent = sch->parent, 288 { 289 .stats.bstats = &sch->bstats, 290 .stats.qstats = &sch->qstats, 291 }, 292 }; 293 int err; 294 295 sch->flags &= ~TCQ_F_OFFLOADED; 296 297 if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc) 298 return 0; 299 300 err = dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED, 301 &hw_stats); 302 if (err == -EOPNOTSUPP) 303 return 0; 304 305 if (!err) 306 sch->flags |= TCQ_F_OFFLOADED; 307 308 return err; 309 } 310 311 static int red_dump(struct Qdisc *sch, struct sk_buff *skb) 312 { 313 struct red_sched_data *q = qdisc_priv(sch); 314 struct nlattr *opts = NULL; 315 struct tc_red_qopt opt = { 316 .limit = q->limit, 317 .flags = q->flags, 318 .qth_min = q->parms.qth_min >> q->parms.Wlog, 319 .qth_max = q->parms.qth_max >> q->parms.Wlog, 320 .Wlog = q->parms.Wlog, 321 .Plog = q->parms.Plog, 322 .Scell_log = q->parms.Scell_log, 323 }; 324 int err; 325 326 err = red_dump_offload_stats(sch, &opt); 327 if (err) 328 goto nla_put_failure; 329 330 opts = nla_nest_start(skb, TCA_OPTIONS); 331 if (opts == NULL) 332 goto nla_put_failure; 333 if (nla_put(skb, TCA_RED_PARMS, sizeof(opt), &opt) || 334 nla_put_u32(skb, TCA_RED_MAX_P, q->parms.max_P)) 335 goto nla_put_failure; 336 return nla_nest_end(skb, opts); 337 338 nla_put_failure: 339 nla_nest_cancel(skb, opts); 340 return -EMSGSIZE; 341 } 342 343 static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d) 344 { 345 struct red_sched_data *q = qdisc_priv(sch); 346 struct net_device *dev = qdisc_dev(sch); 347 struct tc_red_xstats st = {0}; 348 349 if (sch->flags & TCQ_F_OFFLOADED) { 350 struct tc_red_qopt_offload hw_stats_request = { 351 .command = TC_RED_XSTATS, 352 .handle = sch->handle, 353 .parent = sch->parent, 354 { 355 .xstats = &q->stats, 356 }, 357 }; 358 dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED, 359 &hw_stats_request); 360 } 361 st.early = q->stats.prob_drop + q->stats.forced_drop; 362 st.pdrop = q->stats.pdrop; 363 st.other = q->stats.other; 364 st.marked = q->stats.prob_mark + q->stats.forced_mark; 365 366 return gnet_stats_copy_app(d, &st, sizeof(st)); 367 } 368 369 static int red_dump_class(struct Qdisc *sch, unsigned long cl, 370 struct sk_buff *skb, struct tcmsg *tcm) 371 { 372 struct red_sched_data *q = qdisc_priv(sch); 373 374 tcm->tcm_handle |= TC_H_MIN(1); 375 tcm->tcm_info = q->qdisc->handle; 376 return 0; 377 } 378 379 static int red_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, 380 struct Qdisc **old, struct netlink_ext_ack *extack) 381 { 382 struct red_sched_data *q = qdisc_priv(sch); 383 384 if (new == NULL) 385 new = &noop_qdisc; 386 387 *old = qdisc_replace(sch, new, &q->qdisc); 388 return 0; 389 } 390 391 static struct Qdisc *red_leaf(struct Qdisc *sch, unsigned long arg) 392 { 393 struct red_sched_data *q = qdisc_priv(sch); 394 return q->qdisc; 395 } 396 397 static unsigned long red_find(struct Qdisc *sch, u32 classid) 398 { 399 return 1; 400 } 401 402 static void red_walk(struct Qdisc *sch, struct qdisc_walker *walker) 403 { 404 if (!walker->stop) { 405 if (walker->count >= walker->skip) 406 if (walker->fn(sch, 1, walker) < 0) { 407 walker->stop = 1; 408 return; 409 } 410 walker->count++; 411 } 412 } 413 414 static const struct Qdisc_class_ops red_class_ops = { 415 .graft = red_graft, 416 .leaf = red_leaf, 417 .find = red_find, 418 .walk = red_walk, 419 .dump = red_dump_class, 420 }; 421 422 static struct Qdisc_ops red_qdisc_ops __read_mostly = { 423 .id = "red", 424 .priv_size = sizeof(struct red_sched_data), 425 .cl_ops = &red_class_ops, 426 .enqueue = red_enqueue, 427 .dequeue = red_dequeue, 428 .peek = red_peek, 429 .init = red_init, 430 .reset = red_reset, 431 .destroy = red_destroy, 432 .change = red_change, 433 .dump = red_dump, 434 .dump_stats = red_dump_stats, 435 .owner = THIS_MODULE, 436 }; 437 438 static int __init red_module_init(void) 439 { 440 return register_qdisc(&red_qdisc_ops); 441 } 442 443 static void __exit red_module_exit(void) 444 { 445 unregister_qdisc(&red_qdisc_ops); 446 } 447 448 module_init(red_module_init) 449 module_exit(red_module_exit) 450 451 MODULE_LICENSE("GPL"); 452