net/sched/sch_red.c

   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/netdevice.h>
  21 #include <linux/skbuff.h>
  22 #include <net/pkt_sched.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 {
  42         u32                     limit;          /* HARD maximal queue length */
  43         unsigned char           flags;
  44         struct red_parms        parms;
  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->parms.qavg = red_calc_qavg(&q->parms, child->qstats.backlog);
  66
  67         if (red_is_idling(&q->parms))
  68                 red_end_of_idle_period(&q->parms);
  69
  70         switch (red_action(&q->parms, q->parms.qavg)) {
  71                 case RED_DONT_MARK:
  72                         break;
  73
  74                 case RED_PROB_MARK:
  75                         sch->qstats.overlimits++;
  76                         if (!red_use_ecn(q) || !INET_ECN_set_ce(skb)) {
  77                                 q->stats.prob_drop++;
  78                                 goto congestion_drop;
  79                         }
  80
  81                         q->stats.prob_mark++;
  82                         break;
  83
  84                 case RED_HARD_MARK:
  85                         sch->qstats.overlimits++;
  86                         if (red_use_harddrop(q) || !red_use_ecn(q) ||
  87                             !INET_ECN_set_ce(skb)) {
  88                                 q->stats.forced_drop++;
  89                                 goto congestion_drop;
  90                         }
  91
  92                         q->stats.forced_mark++;
  93                         break;
  94         }
  95
  96         ret = child->enqueue(skb, child);
  97         if (likely(ret == NET_XMIT_SUCCESS)) {
  98                 sch->bstats.bytes += skb->len;
  99                 sch->bstats.packets++;
 100                 sch->q.qlen++;
 101         } else {
 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 int red_requeue(struct sk_buff *skb, struct Qdisc* sch)
 113 {
 114         struct red_sched_data *q = qdisc_priv(sch);
 115         struct Qdisc *child = q->qdisc;
 116         int ret;
 117
 118         if (red_is_idling(&q->parms))
 119                 red_end_of_idle_period(&q->parms);
 120
 121         ret = child->ops->requeue(skb, child);
 122         if (likely(ret == NET_XMIT_SUCCESS)) {
 123                 sch->qstats.requeues++;
 124                 sch->q.qlen++;
 125         }
 126         return ret;
 127 }
 128
 129 static struct sk_buff * red_dequeue(struct Qdisc* sch)
 130 {
 131         struct sk_buff *skb;
 132         struct red_sched_data *q = qdisc_priv(sch);
 133         struct Qdisc *child = q->qdisc;
 134
 135         skb = child->dequeue(child);
 136         if (skb)
 137                 sch->q.qlen--;
 138         else if (!red_is_idling(&q->parms))
 139                 red_start_of_idle_period(&q->parms);
 140
 141         return skb;
 142 }
 143
 144 static unsigned int red_drop(struct Qdisc* sch)
 145 {
 146         struct red_sched_data *q = qdisc_priv(sch);
 147         struct Qdisc *child = q->qdisc;
 148         unsigned int len;
 149
 150         if (child->ops->drop && (len = child->ops->drop(child)) > 0) {
 151                 q->stats.other++;
 152                 sch->qstats.drops++;
 153                 sch->q.qlen--;
 154                 return len;
 155         }
 156
 157         if (!red_is_idling(&q->parms))
 158                 red_start_of_idle_period(&q->parms);
 159
 160         return 0;
 161 }
 162
 163 static void red_reset(struct Qdisc* sch)
 164 {
 165         struct red_sched_data *q = qdisc_priv(sch);
 166
 167         qdisc_reset(q->qdisc);
 168         sch->q.qlen = 0;
 169         red_restart(&q->parms);
 170 }
 171
 172 static void red_destroy(struct Qdisc *sch)
 173 {
 174         struct red_sched_data *q = qdisc_priv(sch);
 175         qdisc_destroy(q->qdisc);
 176 }
 177
 178 static struct Qdisc *red_create_dflt(struct net_device *dev, u32 limit)
 179 {
 180         struct Qdisc *q = qdisc_create_dflt(dev, &bfifo_qdisc_ops);
 181         struct rtattr *rta;
 182         int ret;
 183
 184         if (q) {
 185                 rta = kmalloc(RTA_LENGTH(sizeof(struct tc_fifo_qopt)),
 186                               GFP_KERNEL);
 187                 if (rta) {
 188                         rta->rta_type = RTM_NEWQDISC;
 189                         rta->rta_len = RTA_LENGTH(sizeof(struct tc_fifo_qopt));
 190                         ((struct tc_fifo_qopt *)RTA_DATA(rta))->limit = limit;
 191
 192                         ret = q->ops->change(q, rta);
 193                         kfree(rta);
 194
 195                         if (ret == 0)
 196                                 return q;
 197                 }
 198                 qdisc_destroy(q);
 199         }
 200         return NULL;
 201 }
 202
 203 static int red_change(struct Qdisc *sch, struct rtattr *opt)
 204 {
 205         struct red_sched_data *q = qdisc_priv(sch);
 206         struct rtattr *tb[TCA_RED_MAX];
 207         struct tc_red_qopt *ctl;
 208         struct Qdisc *child = NULL;
 209
 210         if (opt == NULL || rtattr_parse_nested(tb, TCA_RED_MAX, opt))
 211                 return -EINVAL;
 212
 213         if (tb[TCA_RED_PARMS-1] == NULL ||
 214             RTA_PAYLOAD(tb[TCA_RED_PARMS-1]) < sizeof(*ctl) ||
 215             tb[TCA_RED_STAB-1] == NULL ||
 216             RTA_PAYLOAD(tb[TCA_RED_STAB-1]) < RED_STAB_SIZE)
 217                 return -EINVAL;
 218
 219         ctl = RTA_DATA(tb[TCA_RED_PARMS-1]);
 220
 221         if (ctl->limit > 0) {
 222                 child = red_create_dflt(sch->dev, ctl->limit);
 223                 if (child == NULL)
 224                         return -ENOMEM;
 225         }
 226
 227         sch_tree_lock(sch);
 228         q->flags = ctl->flags;
 229         q->limit = ctl->limit;
 230         if (child)
 231                 qdisc_destroy(xchg(&q->qdisc, child));
 232
 233         red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
 234                                  ctl->Plog, ctl->Scell_log,
 235                                  RTA_DATA(tb[TCA_RED_STAB-1]));
 236
 237         if (skb_queue_empty(&sch->q))
 238                 red_end_of_idle_period(&q->parms);
 239
 240         sch_tree_unlock(sch);
 241         return 0;
 242 }
 243
 244 static int red_init(struct Qdisc* sch, struct rtattr *opt)
 245 {
 246         struct red_sched_data *q = qdisc_priv(sch);
 247
 248         q->qdisc = &noop_qdisc;
 249         return red_change(sch, opt);
 250 }
 251
 252 static int red_dump(struct Qdisc *sch, struct sk_buff *skb)
 253 {
 254         struct red_sched_data *q = qdisc_priv(sch);
 255         struct rtattr *opts = NULL;
 256         struct tc_red_qopt opt = {
 257                 .limit          = q->limit,
 258                 .flags          = q->flags,
 259                 .qth_min        = q->parms.qth_min >> q->parms.Wlog,
 260                 .qth_max        = q->parms.qth_max >> q->parms.Wlog,
 261                 .Wlog           = q->parms.Wlog,
 262                 .Plog           = q->parms.Plog,
 263                 .Scell_log      = q->parms.Scell_log,
 264         };
 265
 266         opts = RTA_NEST(skb, TCA_OPTIONS);
 267         RTA_PUT(skb, TCA_RED_PARMS, sizeof(opt), &opt);
 268         return RTA_NEST_END(skb, opts);
 269
 270 rtattr_failure:
 271         return RTA_NEST_CANCEL(skb, opts);
 272 }
 273
 274 static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 275 {
 276         struct red_sched_data *q = qdisc_priv(sch);
 277         struct tc_red_xstats st = {
 278                 .early  = q->stats.prob_drop + q->stats.forced_drop,
 279                 .pdrop  = q->stats.pdrop,
 280                 .other  = q->stats.other,
 281                 .marked = q->stats.prob_mark + q->stats.forced_mark,
 282         };
 283
 284         return gnet_stats_copy_app(d, &st, sizeof(st));
 285 }
 286
 287 static int red_dump_class(struct Qdisc *sch, unsigned long cl,
 288                           struct sk_buff *skb, struct tcmsg *tcm)
 289 {
 290         struct red_sched_data *q = qdisc_priv(sch);
 291
 292         if (cl != 1)
 293                 return -ENOENT;
 294         tcm->tcm_handle |= TC_H_MIN(1);
 295         tcm->tcm_info = q->qdisc->handle;
 296         return 0;
 297 }
 298
 299 static int red_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 300                      struct Qdisc **old)
 301 {
 302         struct red_sched_data *q = qdisc_priv(sch);
 303
 304         if (new == NULL)
 305                 new = &noop_qdisc;
 306
 307         sch_tree_lock(sch);
 308         *old = xchg(&q->qdisc, new);
 309         qdisc_reset(*old);
 310         sch->q.qlen = 0;
 311         sch_tree_unlock(sch);
 312         return 0;
 313 }
 314
 315 static struct Qdisc *red_leaf(struct Qdisc *sch, unsigned long arg)
 316 {
 317         struct red_sched_data *q = qdisc_priv(sch);
 318         return q->qdisc;
 319 }
 320
 321 static unsigned long red_get(struct Qdisc *sch, u32 classid)
 322 {
 323         return 1;
 324 }
 325
 326 static void red_put(struct Qdisc *sch, unsigned long arg)
 327 {
 328         return;
 329 }
 330
 331 static int red_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 332                             struct rtattr **tca, unsigned long *arg)
 333 {
 334         return -ENOSYS;
 335 }
 336
 337 static int red_delete(struct Qdisc *sch, unsigned long cl)
 338 {
 339         return -ENOSYS;
 340 }
 341
 342 static void red_walk(struct Qdisc *sch, struct qdisc_walker *walker)
 343 {
 344         if (!walker->stop) {
 345                 if (walker->count >= walker->skip)
 346                         if (walker->fn(sch, 1, walker) < 0) {
 347                                 walker->stop = 1;
 348                                 return;
 349                         }
 350                 walker->count++;
 351         }
 352 }
 353
 354 static struct tcf_proto **red_find_tcf(struct Qdisc *sch, unsigned long cl)
 355 {
 356         return NULL;
 357 }
 358
 359 static struct Qdisc_class_ops red_class_ops = {
 360         .graft          =       red_graft,
 361         .leaf           =       red_leaf,
 362         .get            =       red_get,
 363         .put            =       red_put,
 364         .change         =       red_change_class,
 365         .delete         =       red_delete,
 366         .walk           =       red_walk,
 367         .tcf_chain      =       red_find_tcf,
 368         .dump           =       red_dump_class,
 369 };
 370
 371 static struct Qdisc_ops red_qdisc_ops = {
 372         .id             =       "red",
 373         .priv_size      =       sizeof(struct red_sched_data),
 374         .cl_ops         =       &red_class_ops,
 375         .enqueue        =       red_enqueue,
 376         .dequeue        =       red_dequeue,
 377         .requeue        =       red_requeue,
 378         .drop           =       red_drop,
 379         .init           =       red_init,
 380         .reset          =       red_reset,
 381         .destroy        =       red_destroy,
 382         .change         =       red_change,
 383         .dump           =       red_dump,
 384         .dump_stats     =       red_dump_stats,
 385         .owner          =       THIS_MODULE,
 386 };
 387
 388 static int __init red_module_init(void)
 389 {
 390         return register_qdisc(&red_qdisc_ops);
 391 }
 392
 393 static void __exit red_module_exit(void)
 394 {
 395         unregister_qdisc(&red_qdisc_ops);
 396 }
 397
 398 module_init(red_module_init)
 399 module_exit(red_module_exit)
 400
 401 MODULE_LICENSE("GPL");