net/sched/sch_tbf.c

   1 /*
   2  * net/sched/sch_tbf.c  Token Bucket Filter 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  *              Dmitry Torokhov <dtor@mail.ru> - allow attaching inner qdiscs -
  11  *                                               original idea by Martin Devera
  12  *
  13  */
  14
  15 #include <linux/config.h>
  16 #include <linux/module.h>
  17 #include <asm/uaccess.h>
  18 #include <asm/system.h>
  19 #include <linux/bitops.h>
  20 #include <linux/types.h>
  21 #include <linux/kernel.h>
  22 #include <linux/jiffies.h>
  23 #include <linux/string.h>
  24 #include <linux/mm.h>
  25 #include <linux/socket.h>
  26 #include <linux/sockios.h>
  27 #include <linux/in.h>
  28 #include <linux/errno.h>
  29 #include <linux/interrupt.h>
  30 #include <linux/if_ether.h>
  31 #include <linux/inet.h>
  32 #include <linux/netdevice.h>
  33 #include <linux/etherdevice.h>
  34 #include <linux/notifier.h>
  35 #include <net/ip.h>
  36 #include <net/route.h>
  37 #include <linux/skbuff.h>
  38 #include <net/sock.h>
  39 #include <net/pkt_sched.h>
  40
  41
  42 /*      Simple Token Bucket Filter.
  43         =======================================
  44
  45         SOURCE.
  46         -------
  47
  48         None.
  49
  50         Description.
  51         ------------
  52
  53         A data flow obeys TBF with rate R and depth B, if for any
  54         time interval t_i...t_f the number of transmitted bits
  55         does not exceed B + R*(t_f-t_i).
  56
  57         Packetized version of this definition:
  58         The sequence of packets of sizes s_i served at moments t_i
  59         obeys TBF, if for any i<=k:
  60
  61         s_i+....+s_k <= B + R*(t_k - t_i)
  62
  63         Algorithm.
  64         ----------
  65
  66         Let N(t_i) be B/R initially and N(t) grow continuously with time as:
  67
  68         N(t+delta) = min{B/R, N(t) + delta}
  69
  70         If the first packet in queue has length S, it may be
  71         transmitted only at the time t_* when S/R <= N(t_*),
  72         and in this case N(t) jumps:
  73
  74         N(t_* + 0) = N(t_* - 0) - S/R.
  75
  76
  77
  78         Actually, QoS requires two TBF to be applied to a data stream.
  79         One of them controls steady state burst size, another
  80         one with rate P (peak rate) and depth M (equal to link MTU)
  81         limits bursts at a smaller time scale.
  82
  83         It is easy to see that P>R, and B>M. If P is infinity, this double
  84         TBF is equivalent to a single one.
  85
  86         When TBF works in reshaping mode, latency is estimated as:
  87
  88         lat = max ((L-B)/R, (L-M)/P)
  89
  90
  91         NOTES.
  92         ------
  93
  94         If TBF throttles, it starts a watchdog timer, which will wake it up
  95         when it is ready to transmit.
  96         Note that the minimal timer resolution is 1/HZ.
  97         If no new packets arrive during this period,
  98         or if the device is not awaken by EOI for some previous packet,
  99         TBF can stop its activity for 1/HZ.
 100
 101
 102         This means, that with depth B, the maximal rate is
 103
 104         R_crit = B*HZ
 105
 106         F.e. for 10Mbit ethernet and HZ=100 the minimal allowed B is ~10Kbytes.
 107
 108         Note that the peak rate TBF is much more tough: with MTU 1500
 109         P_crit = 150Kbytes/sec. So, if you need greater peak
 110         rates, use alpha with HZ=1000 :-)
 111
 112         With classful TBF, limit is just kept for backwards compatibility.
 113         It is passed to the default bfifo qdisc - if the inner qdisc is
 114         changed the limit is not effective anymore.
 115 */
 116
 117 struct tbf_sched_data
 118 {
 119 /* Parameters */
 120         u32             limit;          /* Maximal length of backlog: bytes */
 121         u32             buffer;         /* Token bucket depth/rate: MUST BE >= MTU/B */
 122         u32             mtu;
 123         u32             max_size;
 124         struct qdisc_rate_table *R_tab;
 125         struct qdisc_rate_table *P_tab;
 126
 127 /* Variables */
 128         long    tokens;                 /* Current number of B tokens */
 129         long    ptokens;                /* Current number of P tokens */
 130         psched_time_t   t_c;            /* Time check-point */
 131         struct timer_list wd_timer;     /* Watchdog timer */
 132         struct Qdisc    *qdisc;         /* Inner qdisc, default - bfifo queue */
 133 };
 134
 135 #define L2T(q,L)   ((q)->R_tab->data[(L)>>(q)->R_tab->rate.cell_log])
 136 #define L2T_P(q,L) ((q)->P_tab->data[(L)>>(q)->P_tab->rate.cell_log])
 137
 138 static int tbf_enqueue(struct sk_buff *skb, struct Qdisc* sch)
 139 {
 140         struct tbf_sched_data *q = qdisc_priv(sch);
 141         int ret;
 142
 143         if (skb->len > q->max_size) {
 144                 sch->qstats.drops++;
 145 #ifdef CONFIG_NET_CLS_POLICE
 146                 if (sch->reshape_fail == NULL || sch->reshape_fail(skb, sch))
 147 #endif
 148                         kfree_skb(skb);
 149
 150                 return NET_XMIT_DROP;
 151         }
 152
 153         if ((ret = q->qdisc->enqueue(skb, q->qdisc)) != 0) {
 154                 sch->qstats.drops++;
 155                 return ret;
 156         }
 157
 158         sch->q.qlen++;
 159         sch->bstats.bytes += skb->len;
 160         sch->bstats.packets++;
 161         return 0;
 162 }
 163
 164 static int tbf_requeue(struct sk_buff *skb, struct Qdisc* sch)
 165 {
 166         struct tbf_sched_data *q = qdisc_priv(sch);
 167         int ret;
 168
 169         if ((ret = q->qdisc->ops->requeue(skb, q->qdisc)) == 0) {
 170                 sch->q.qlen++;
 171                 sch->qstats.requeues++;
 172         }
 173
 174         return ret;
 175 }
 176
 177 static unsigned int tbf_drop(struct Qdisc* sch)
 178 {
 179         struct tbf_sched_data *q = qdisc_priv(sch);
 180         unsigned int len = 0;
 181
 182         if (q->qdisc->ops->drop && (len = q->qdisc->ops->drop(q->qdisc)) != 0) {
 183                 sch->q.qlen--;
 184                 sch->qstats.drops++;
 185         }
 186         return len;
 187 }
 188
 189 static void tbf_watchdog(unsigned long arg)
 190 {
 191         struct Qdisc *sch = (struct Qdisc*)arg;
 192
 193         sch->flags &= ~TCQ_F_THROTTLED;
 194         netif_schedule(sch->dev);
 195 }
 196
 197 static struct sk_buff *tbf_dequeue(struct Qdisc* sch)
 198 {
 199         struct tbf_sched_data *q = qdisc_priv(sch);
 200         struct sk_buff *skb;
 201
 202         skb = q->qdisc->dequeue(q->qdisc);
 203
 204         if (skb) {
 205                 psched_time_t now;
 206                 long toks, delay;
 207                 long ptoks = 0;
 208                 unsigned int len = skb->len;
 209
 210                 PSCHED_GET_TIME(now);
 211
 212                 toks = PSCHED_TDIFF_SAFE(now, q->t_c, q->buffer);
 213
 214                 if (q->P_tab) {
 215                         ptoks = toks + q->ptokens;
 216                         if (ptoks > (long)q->mtu)
 217                                 ptoks = q->mtu;
 218                         ptoks -= L2T_P(q, len);
 219                 }
 220                 toks += q->tokens;
 221                 if (toks > (long)q->buffer)
 222                         toks = q->buffer;
 223                 toks -= L2T(q, len);
 224
 225                 if ((toks|ptoks) >= 0) {
 226                         q->t_c = now;
 227                         q->tokens = toks;
 228                         q->ptokens = ptoks;
 229                         sch->q.qlen--;
 230                         sch->flags &= ~TCQ_F_THROTTLED;
 231                         return skb;
 232                 }
 233
 234                 delay = PSCHED_US2JIFFIE(max_t(long, -toks, -ptoks));
 235
 236                 if (delay == 0)
 237                         delay = 1;
 238
 239                 mod_timer(&q->wd_timer, jiffies+delay);
 240
 241                 /* Maybe we have a shorter packet in the queue,
 242                    which can be sent now. It sounds cool,
 243                    but, however, this is wrong in principle.
 244                    We MUST NOT reorder packets under these circumstances.
 245
 246                    Really, if we split the flow into independent
 247                    subflows, it would be a very good solution.
 248                    This is the main idea of all FQ algorithms
 249                    (cf. CSZ, HPFQ, HFSC)
 250                  */
 251
 252                 if (q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS) {
 253                         /* When requeue fails skb is dropped */
 254                         sch->q.qlen--;
 255                         sch->qstats.drops++;
 256                 }
 257
 258                 sch->flags |= TCQ_F_THROTTLED;
 259                 sch->qstats.overlimits++;
 260         }
 261         return NULL;
 262 }
 263
 264 static void tbf_reset(struct Qdisc* sch)
 265 {
 266         struct tbf_sched_data *q = qdisc_priv(sch);
 267
 268         qdisc_reset(q->qdisc);
 269         sch->q.qlen = 0;
 270         PSCHED_GET_TIME(q->t_c);
 271         q->tokens = q->buffer;
 272         q->ptokens = q->mtu;
 273         sch->flags &= ~TCQ_F_THROTTLED;
 274         del_timer(&q->wd_timer);
 275 }
 276
 277 static struct Qdisc *tbf_create_dflt_qdisc(struct net_device *dev, u32 limit)
 278 {
 279         struct Qdisc *q = qdisc_create_dflt(dev, &bfifo_qdisc_ops);
 280         struct rtattr *rta;
 281         int ret;
 282
 283         if (q) {
 284                 rta = kmalloc(RTA_LENGTH(sizeof(struct tc_fifo_qopt)), GFP_KERNEL);
 285                 if (rta) {
 286                         rta->rta_type = RTM_NEWQDISC;
 287                         rta->rta_len = RTA_LENGTH(sizeof(struct tc_fifo_qopt));
 288                         ((struct tc_fifo_qopt *)RTA_DATA(rta))->limit = limit;
 289
 290                         ret = q->ops->change(q, rta);
 291                         kfree(rta);
 292
 293                         if (ret == 0)
 294                                 return q;
 295                 }
 296                 qdisc_destroy(q);
 297         }
 298
 299         return NULL;
 300 }
 301
 302 static int tbf_change(struct Qdisc* sch, struct rtattr *opt)
 303 {
 304         int err = -EINVAL;
 305         struct tbf_sched_data *q = qdisc_priv(sch);
 306         struct rtattr *tb[TCA_TBF_PTAB];
 307         struct tc_tbf_qopt *qopt;
 308         struct qdisc_rate_table *rtab = NULL;
 309         struct qdisc_rate_table *ptab = NULL;
 310         struct Qdisc *child = NULL;
 311         int max_size,n;
 312
 313         if (rtattr_parse_nested(tb, TCA_TBF_PTAB, opt) ||
 314             tb[TCA_TBF_PARMS-1] == NULL ||
 315             RTA_PAYLOAD(tb[TCA_TBF_PARMS-1]) < sizeof(*qopt))
 316                 goto done;
 317
 318         qopt = RTA_DATA(tb[TCA_TBF_PARMS-1]);
 319         rtab = qdisc_get_rtab(&qopt->rate, tb[TCA_TBF_RTAB-1]);
 320         if (rtab == NULL)
 321                 goto done;
 322
 323         if (qopt->peakrate.rate) {
 324                 if (qopt->peakrate.rate > qopt->rate.rate)
 325                         ptab = qdisc_get_rtab(&qopt->peakrate, tb[TCA_TBF_PTAB-1]);
 326                 if (ptab == NULL)
 327                         goto done;
 328         }
 329
 330         for (n = 0; n < 256; n++)
 331                 if (rtab->data[n] > qopt->buffer) break;
 332         max_size = (n << qopt->rate.cell_log)-1;
 333         if (ptab) {
 334                 int size;
 335
 336                 for (n = 0; n < 256; n++)
 337                         if (ptab->data[n] > qopt->mtu) break;
 338                 size = (n << qopt->peakrate.cell_log)-1;
 339                 if (size < max_size) max_size = size;
 340         }
 341         if (max_size < 0)
 342                 goto done;
 343
 344         if (qopt->limit > 0) {
 345                 if ((child = tbf_create_dflt_qdisc(sch->dev, qopt->limit)) == NULL)
 346                         goto done;
 347         }
 348
 349         sch_tree_lock(sch);
 350         if (child)
 351                 qdisc_destroy(xchg(&q->qdisc, child));
 352         q->limit = qopt->limit;
 353         q->mtu = qopt->mtu;
 354         q->max_size = max_size;
 355         q->buffer = qopt->buffer;
 356         q->tokens = q->buffer;
 357         q->ptokens = q->mtu;
 358         rtab = xchg(&q->R_tab, rtab);
 359         ptab = xchg(&q->P_tab, ptab);
 360         sch_tree_unlock(sch);
 361         err = 0;
 362 done:
 363         if (rtab)
 364                 qdisc_put_rtab(rtab);
 365         if (ptab)
 366                 qdisc_put_rtab(ptab);
 367         return err;
 368 }
 369
 370 static int tbf_init(struct Qdisc* sch, struct rtattr *opt)
 371 {
 372         struct tbf_sched_data *q = qdisc_priv(sch);
 373
 374         if (opt == NULL)
 375                 return -EINVAL;
 376
 377         PSCHED_GET_TIME(q->t_c);
 378         init_timer(&q->wd_timer);
 379         q->wd_timer.function = tbf_watchdog;
 380         q->wd_timer.data = (unsigned long)sch;
 381
 382         q->qdisc = &noop_qdisc;
 383
 384         return tbf_change(sch, opt);
 385 }
 386
 387 static void tbf_destroy(struct Qdisc *sch)
 388 {
 389         struct tbf_sched_data *q = qdisc_priv(sch);
 390
 391         del_timer(&q->wd_timer);
 392
 393         if (q->P_tab)
 394                 qdisc_put_rtab(q->P_tab);
 395         if (q->R_tab)
 396                 qdisc_put_rtab(q->R_tab);
 397
 398         qdisc_destroy(q->qdisc);
 399 }
 400
 401 static int tbf_dump(struct Qdisc *sch, struct sk_buff *skb)
 402 {
 403         struct tbf_sched_data *q = qdisc_priv(sch);
 404         unsigned char    *b = skb->tail;
 405         struct rtattr *rta;
 406         struct tc_tbf_qopt opt;
 407
 408         rta = (struct rtattr*)b;
 409         RTA_PUT(skb, TCA_OPTIONS, 0, NULL);
 410
 411         opt.limit = q->limit;
 412         opt.rate = q->R_tab->rate;
 413         if (q->P_tab)
 414                 opt.peakrate = q->P_tab->rate;
 415         else
 416                 memset(&opt.peakrate, 0, sizeof(opt.peakrate));
 417         opt.mtu = q->mtu;
 418         opt.buffer = q->buffer;
 419         RTA_PUT(skb, TCA_TBF_PARMS, sizeof(opt), &opt);
 420         rta->rta_len = skb->tail - b;
 421
 422         return skb->len;
 423
 424 rtattr_failure:
 425         skb_trim(skb, b - skb->data);
 426         return -1;
 427 }
 428
 429 static int tbf_dump_class(struct Qdisc *sch, unsigned long cl,
 430                           struct sk_buff *skb, struct tcmsg *tcm)
 431 {
 432         struct tbf_sched_data *q = qdisc_priv(sch);
 433
 434         if (cl != 1)    /* only one class */
 435                 return -ENOENT;
 436
 437         tcm->tcm_handle |= TC_H_MIN(1);
 438         tcm->tcm_info = q->qdisc->handle;
 439
 440         return 0;
 441 }
 442
 443 static int tbf_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 444                      struct Qdisc **old)
 445 {
 446         struct tbf_sched_data *q = qdisc_priv(sch);
 447
 448         if (new == NULL)
 449                 new = &noop_qdisc;
 450
 451         sch_tree_lock(sch);
 452         *old = xchg(&q->qdisc, new);
 453         qdisc_reset(*old);
 454         sch->q.qlen = 0;
 455         sch_tree_unlock(sch);
 456
 457         return 0;
 458 }
 459
 460 static struct Qdisc *tbf_leaf(struct Qdisc *sch, unsigned long arg)
 461 {
 462         struct tbf_sched_data *q = qdisc_priv(sch);
 463         return q->qdisc;
 464 }
 465
 466 static unsigned long tbf_get(struct Qdisc *sch, u32 classid)
 467 {
 468         return 1;
 469 }
 470
 471 static void tbf_put(struct Qdisc *sch, unsigned long arg)
 472 {
 473 }
 474
 475 static int tbf_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 476                             struct rtattr **tca, unsigned long *arg)
 477 {
 478         return -ENOSYS;
 479 }
 480
 481 static int tbf_delete(struct Qdisc *sch, unsigned long arg)
 482 {
 483         return -ENOSYS;
 484 }
 485
 486 static void tbf_walk(struct Qdisc *sch, struct qdisc_walker *walker)
 487 {
 488         if (!walker->stop) {
 489                 if (walker->count >= walker->skip)
 490                         if (walker->fn(sch, 1, walker) < 0) {
 491                                 walker->stop = 1;
 492                                 return;
 493                         }
 494                 walker->count++;
 495         }
 496 }
 497
 498 static struct tcf_proto **tbf_find_tcf(struct Qdisc *sch, unsigned long cl)
 499 {
 500         return NULL;
 501 }
 502
 503 static struct Qdisc_class_ops tbf_class_ops =
 504 {
 505         .graft          =       tbf_graft,
 506         .leaf           =       tbf_leaf,
 507         .get            =       tbf_get,
 508         .put            =       tbf_put,
 509         .change         =       tbf_change_class,
 510         .delete         =       tbf_delete,
 511         .walk           =       tbf_walk,
 512         .tcf_chain      =       tbf_find_tcf,
 513         .dump           =       tbf_dump_class,
 514 };
 515
 516 static struct Qdisc_ops tbf_qdisc_ops = {
 517         .next           =       NULL,
 518         .cl_ops         =       &tbf_class_ops,
 519         .id             =       "tbf",
 520         .priv_size      =       sizeof(struct tbf_sched_data),
 521         .enqueue        =       tbf_enqueue,
 522         .dequeue        =       tbf_dequeue,
 523         .requeue        =       tbf_requeue,
 524         .drop           =       tbf_drop,
 525         .init           =       tbf_init,
 526         .reset          =       tbf_reset,
 527         .destroy        =       tbf_destroy,
 528         .change         =       tbf_change,
 529         .dump           =       tbf_dump,
 530         .owner          =       THIS_MODULE,
 531 };
 532
 533 static int __init tbf_module_init(void)
 534 {
 535         return register_qdisc(&tbf_qdisc_ops);
 536 }
 537
 538 static void __exit tbf_module_exit(void)
 539 {
 540         unregister_qdisc(&tbf_qdisc_ops);
 541 }
 542 module_init(tbf_module_init)
 543 module_exit(tbf_module_exit)
 544 MODULE_LICENSE("GPL");