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/inet_ecn.h> 23 #include <net/red.h> 24 25 26 /* Parameters, settable by user: 27 ----------------------------- 28 29 limit - bytes (must be > qth_max + burst) 30 31 Hard limit on queue length, should be chosen >qth_max 32 to allow packet bursts. This parameter does not 33 affect the algorithms behaviour and can be chosen 34 arbitrarily high (well, less than ram size) 35 Really, this limit will never be reached 36 if RED works correctly. 37 */ 38 39 struct red_sched_data { 40 u32 limit; /* HARD maximal queue length */ 41 unsigned char flags; 42 struct timer_list adapt_timer; 43 struct red_parms parms; 44 struct red_vars vars; 45 struct red_stats stats; 46 struct Qdisc *qdisc; 47 }; 48 49 static inline int red_use_ecn(struct red_sched_data *q) 50 { 51 return q->flags & TC_RED_ECN; 52 } 53 54 static inline int red_use_harddrop(struct red_sched_data *q) 55 { 56 return q->flags & TC_RED_HARDDROP; 57 } 58 59 static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch) 60 { 61 struct red_sched_data *q = qdisc_priv(sch); 62 struct Qdisc *child = q->qdisc; 63 int ret; 64 65 q->vars.qavg = red_calc_qavg(&q->parms, 66 &q->vars, 67 child->qstats.backlog); 68 69 if (red_is_idling(&q->vars)) 70 red_end_of_idle_period(&q->vars); 71 72 switch (red_action(&q->parms, &q->vars, q->vars.qavg)) { 73 case RED_DONT_MARK: 74 break; 75 76 case RED_PROB_MARK: 77 sch->qstats.overlimits++; 78 if (!red_use_ecn(q) || !INET_ECN_set_ce(skb)) { 79 q->stats.prob_drop++; 80 goto congestion_drop; 81 } 82 83 q->stats.prob_mark++; 84 break; 85 86 case RED_HARD_MARK: 87 sch->qstats.overlimits++; 88 if (red_use_harddrop(q) || !red_use_ecn(q) || 89 !INET_ECN_set_ce(skb)) { 90 q->stats.forced_drop++; 91 goto congestion_drop; 92 } 93 94 q->stats.forced_mark++; 95 break; 96 } 97 98 ret = qdisc_enqueue(skb, child); 99 if (likely(ret == NET_XMIT_SUCCESS)) { 100 sch->q.qlen++; 101 } else if (net_xmit_drop_count(ret)) { 102 q->stats.pdrop++; 103 sch->qstats.drops++; 104 } 105 return ret; 106 107 congestion_drop: 108 qdisc_drop(skb, sch); 109 return NET_XMIT_CN; 110 } 111 112 static struct sk_buff *red_dequeue(struct Qdisc *sch) 113 { 114 struct sk_buff *skb; 115 struct red_sched_data *q = qdisc_priv(sch); 116 struct Qdisc *child = q->qdisc; 117 118 skb = child->dequeue(child); 119 if (skb) { 120 qdisc_bstats_update(sch, skb); 121 sch->q.qlen--; 122 } else { 123 if (!red_is_idling(&q->vars)) 124 red_start_of_idle_period(&q->vars); 125 } 126 return skb; 127 } 128 129 static struct sk_buff *red_peek(struct Qdisc *sch) 130 { 131 struct red_sched_data *q = qdisc_priv(sch); 132 struct Qdisc *child = q->qdisc; 133 134 return child->ops->peek(child); 135 } 136 137 static unsigned int red_drop(struct Qdisc *sch) 138 { 139 struct red_sched_data *q = qdisc_priv(sch); 140 struct Qdisc *child = q->qdisc; 141 unsigned int len; 142 143 if (child->ops->drop && (len = child->ops->drop(child)) > 0) { 144 q->stats.other++; 145 sch->qstats.drops++; 146 sch->q.qlen--; 147 return len; 148 } 149 150 if (!red_is_idling(&q->vars)) 151 red_start_of_idle_period(&q->vars); 152 153 return 0; 154 } 155 156 static void red_reset(struct Qdisc *sch) 157 { 158 struct red_sched_data *q = qdisc_priv(sch); 159 160 qdisc_reset(q->qdisc); 161 sch->q.qlen = 0; 162 red_restart(&q->vars); 163 } 164 165 static void red_destroy(struct Qdisc *sch) 166 { 167 struct red_sched_data *q = qdisc_priv(sch); 168 169 del_timer_sync(&q->adapt_timer); 170 qdisc_destroy(q->qdisc); 171 } 172 173 static const struct nla_policy red_policy[TCA_RED_MAX + 1] = { 174 [TCA_RED_PARMS] = { .len = sizeof(struct tc_red_qopt) }, 175 [TCA_RED_STAB] = { .len = RED_STAB_SIZE }, 176 [TCA_RED_MAX_P] = { .type = NLA_U32 }, 177 }; 178 179 static int red_change(struct Qdisc *sch, struct nlattr *opt) 180 { 181 struct red_sched_data *q = qdisc_priv(sch); 182 struct nlattr *tb[TCA_RED_MAX + 1]; 183 struct tc_red_qopt *ctl; 184 struct Qdisc *child = NULL; 185 int err; 186 u32 max_P; 187 188 if (opt == NULL) 189 return -EINVAL; 190 191 err = nla_parse_nested(tb, TCA_RED_MAX, opt, red_policy); 192 if (err < 0) 193 return err; 194 195 if (tb[TCA_RED_PARMS] == NULL || 196 tb[TCA_RED_STAB] == NULL) 197 return -EINVAL; 198 199 max_P = tb[TCA_RED_MAX_P] ? nla_get_u32(tb[TCA_RED_MAX_P]) : 0; 200 201 ctl = nla_data(tb[TCA_RED_PARMS]); 202 203 if (ctl->limit > 0) { 204 child = fifo_create_dflt(sch, &bfifo_qdisc_ops, ctl->limit); 205 if (IS_ERR(child)) 206 return PTR_ERR(child); 207 } 208 209 sch_tree_lock(sch); 210 q->flags = ctl->flags; 211 q->limit = ctl->limit; 212 if (child) { 213 qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen); 214 qdisc_destroy(q->qdisc); 215 q->qdisc = child; 216 } 217 218 red_set_parms(&q->parms, 219 ctl->qth_min, ctl->qth_max, ctl->Wlog, 220 ctl->Plog, ctl->Scell_log, 221 nla_data(tb[TCA_RED_STAB]), 222 max_P); 223 red_set_vars(&q->vars); 224 225 del_timer(&q->adapt_timer); 226 if (ctl->flags & TC_RED_ADAPTATIVE) 227 mod_timer(&q->adapt_timer, jiffies + HZ/2); 228 229 if (!q->qdisc->q.qlen) 230 red_start_of_idle_period(&q->vars); 231 232 sch_tree_unlock(sch); 233 return 0; 234 } 235 236 static inline void red_adaptative_timer(unsigned long arg) 237 { 238 struct Qdisc *sch = (struct Qdisc *)arg; 239 struct red_sched_data *q = qdisc_priv(sch); 240 spinlock_t *root_lock = qdisc_lock(qdisc_root_sleeping(sch)); 241 242 spin_lock(root_lock); 243 red_adaptative_algo(&q->parms, &q->vars); 244 mod_timer(&q->adapt_timer, jiffies + HZ/2); 245 spin_unlock(root_lock); 246 } 247 248 static int red_init(struct Qdisc *sch, struct nlattr *opt) 249 { 250 struct red_sched_data *q = qdisc_priv(sch); 251 252 q->qdisc = &noop_qdisc; 253 setup_timer(&q->adapt_timer, red_adaptative_timer, (unsigned long)sch); 254 return red_change(sch, opt); 255 } 256 257 static int red_dump(struct Qdisc *sch, struct sk_buff *skb) 258 { 259 struct red_sched_data *q = qdisc_priv(sch); 260 struct nlattr *opts = NULL; 261 struct tc_red_qopt opt = { 262 .limit = q->limit, 263 .flags = q->flags, 264 .qth_min = q->parms.qth_min >> q->parms.Wlog, 265 .qth_max = q->parms.qth_max >> q->parms.Wlog, 266 .Wlog = q->parms.Wlog, 267 .Plog = q->parms.Plog, 268 .Scell_log = q->parms.Scell_log, 269 }; 270 271 sch->qstats.backlog = q->qdisc->qstats.backlog; 272 opts = nla_nest_start(skb, TCA_OPTIONS); 273 if (opts == NULL) 274 goto nla_put_failure; 275 if (nla_put(skb, TCA_RED_PARMS, sizeof(opt), &opt) || 276 nla_put_u32(skb, TCA_RED_MAX_P, q->parms.max_P)) 277 goto nla_put_failure; 278 return nla_nest_end(skb, opts); 279 280 nla_put_failure: 281 nla_nest_cancel(skb, opts); 282 return -EMSGSIZE; 283 } 284 285 static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d) 286 { 287 struct red_sched_data *q = qdisc_priv(sch); 288 struct tc_red_xstats st = { 289 .early = q->stats.prob_drop + q->stats.forced_drop, 290 .pdrop = q->stats.pdrop, 291 .other = q->stats.other, 292 .marked = q->stats.prob_mark + q->stats.forced_mark, 293 }; 294 295 return gnet_stats_copy_app(d, &st, sizeof(st)); 296 } 297 298 static int red_dump_class(struct Qdisc *sch, unsigned long cl, 299 struct sk_buff *skb, struct tcmsg *tcm) 300 { 301 struct red_sched_data *q = qdisc_priv(sch); 302 303 tcm->tcm_handle |= TC_H_MIN(1); 304 tcm->tcm_info = q->qdisc->handle; 305 return 0; 306 } 307 308 static int red_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, 309 struct Qdisc **old) 310 { 311 struct red_sched_data *q = qdisc_priv(sch); 312 313 if (new == NULL) 314 new = &noop_qdisc; 315 316 sch_tree_lock(sch); 317 *old = q->qdisc; 318 q->qdisc = new; 319 qdisc_tree_decrease_qlen(*old, (*old)->q.qlen); 320 qdisc_reset(*old); 321 sch_tree_unlock(sch); 322 return 0; 323 } 324 325 static struct Qdisc *red_leaf(struct Qdisc *sch, unsigned long arg) 326 { 327 struct red_sched_data *q = qdisc_priv(sch); 328 return q->qdisc; 329 } 330 331 static unsigned long red_get(struct Qdisc *sch, u32 classid) 332 { 333 return 1; 334 } 335 336 static void red_put(struct Qdisc *sch, unsigned long arg) 337 { 338 } 339 340 static void red_walk(struct Qdisc *sch, struct qdisc_walker *walker) 341 { 342 if (!walker->stop) { 343 if (walker->count >= walker->skip) 344 if (walker->fn(sch, 1, walker) < 0) { 345 walker->stop = 1; 346 return; 347 } 348 walker->count++; 349 } 350 } 351 352 static const struct Qdisc_class_ops red_class_ops = { 353 .graft = red_graft, 354 .leaf = red_leaf, 355 .get = red_get, 356 .put = red_put, 357 .walk = red_walk, 358 .dump = red_dump_class, 359 }; 360 361 static struct Qdisc_ops red_qdisc_ops __read_mostly = { 362 .id = "red", 363 .priv_size = sizeof(struct red_sched_data), 364 .cl_ops = &red_class_ops, 365 .enqueue = red_enqueue, 366 .dequeue = red_dequeue, 367 .peek = red_peek, 368 .drop = red_drop, 369 .init = red_init, 370 .reset = red_reset, 371 .destroy = red_destroy, 372 .change = red_change, 373 .dump = red_dump, 374 .dump_stats = red_dump_stats, 375 .owner = THIS_MODULE, 376 }; 377 378 static int __init red_module_init(void) 379 { 380 return register_qdisc(&red_qdisc_ops); 381 } 382 383 static void __exit red_module_exit(void) 384 { 385 unregister_qdisc(&red_qdisc_ops); 386 } 387 388 module_init(red_module_init) 389 module_exit(red_module_exit) 390 391 MODULE_LICENSE("GPL"); 392