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 NLA_PUT(skb, TCA_RED_PARMS, sizeof(opt), &opt); 276 NLA_PUT_U32(skb, TCA_RED_MAX_P, q->parms.max_P); 277 return nla_nest_end(skb, opts); 278 279 nla_put_failure: 280 nla_nest_cancel(skb, opts); 281 return -EMSGSIZE; 282 } 283 284 static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d) 285 { 286 struct red_sched_data *q = qdisc_priv(sch); 287 struct tc_red_xstats st = { 288 .early = q->stats.prob_drop + q->stats.forced_drop, 289 .pdrop = q->stats.pdrop, 290 .other = q->stats.other, 291 .marked = q->stats.prob_mark + q->stats.forced_mark, 292 }; 293 294 return gnet_stats_copy_app(d, &st, sizeof(st)); 295 } 296 297 static int red_dump_class(struct Qdisc *sch, unsigned long cl, 298 struct sk_buff *skb, struct tcmsg *tcm) 299 { 300 struct red_sched_data *q = qdisc_priv(sch); 301 302 tcm->tcm_handle |= TC_H_MIN(1); 303 tcm->tcm_info = q->qdisc->handle; 304 return 0; 305 } 306 307 static int red_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, 308 struct Qdisc **old) 309 { 310 struct red_sched_data *q = qdisc_priv(sch); 311 312 if (new == NULL) 313 new = &noop_qdisc; 314 315 sch_tree_lock(sch); 316 *old = q->qdisc; 317 q->qdisc = new; 318 qdisc_tree_decrease_qlen(*old, (*old)->q.qlen); 319 qdisc_reset(*old); 320 sch_tree_unlock(sch); 321 return 0; 322 } 323 324 static struct Qdisc *red_leaf(struct Qdisc *sch, unsigned long arg) 325 { 326 struct red_sched_data *q = qdisc_priv(sch); 327 return q->qdisc; 328 } 329 330 static unsigned long red_get(struct Qdisc *sch, u32 classid) 331 { 332 return 1; 333 } 334 335 static void red_put(struct Qdisc *sch, unsigned long arg) 336 { 337 } 338 339 static void red_walk(struct Qdisc *sch, struct qdisc_walker *walker) 340 { 341 if (!walker->stop) { 342 if (walker->count >= walker->skip) 343 if (walker->fn(sch, 1, walker) < 0) { 344 walker->stop = 1; 345 return; 346 } 347 walker->count++; 348 } 349 } 350 351 static const struct Qdisc_class_ops red_class_ops = { 352 .graft = red_graft, 353 .leaf = red_leaf, 354 .get = red_get, 355 .put = red_put, 356 .walk = red_walk, 357 .dump = red_dump_class, 358 }; 359 360 static struct Qdisc_ops red_qdisc_ops __read_mostly = { 361 .id = "red", 362 .priv_size = sizeof(struct red_sched_data), 363 .cl_ops = &red_class_ops, 364 .enqueue = red_enqueue, 365 .dequeue = red_dequeue, 366 .peek = red_peek, 367 .drop = red_drop, 368 .init = red_init, 369 .reset = red_reset, 370 .destroy = red_destroy, 371 .change = red_change, 372 .dump = red_dump, 373 .dump_stats = red_dump_stats, 374 .owner = THIS_MODULE, 375 }; 376 377 static int __init red_module_init(void) 378 { 379 return register_qdisc(&red_qdisc_ops); 380 } 381 382 static void __exit red_module_exit(void) 383 { 384 unregister_qdisc(&red_qdisc_ops); 385 } 386 387 module_init(red_module_init) 388 module_exit(red_module_exit) 389 390 MODULE_LICENSE("GPL"); 391