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1da177e4 LT |
1 | /* |
2 | * net/sched/sch_netem.c Network emulator | |
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 | * Many of the algorithms and ideas for this came from | |
10 | * NIST Net which is not copyrighted. | |
11 | * | |
12 | * Authors: Stephen Hemminger <shemminger@osdl.org> | |
13 | * Catalin(ux aka Dino) BOIE <catab at umbrella dot ro> | |
14 | */ | |
15 | ||
16 | #include <linux/config.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/bitops.h> | |
19 | #include <linux/types.h> | |
20 | #include <linux/kernel.h> | |
21 | #include <linux/errno.h> | |
22 | #include <linux/netdevice.h> | |
23 | #include <linux/skbuff.h> | |
24 | #include <linux/rtnetlink.h> | |
25 | ||
26 | #include <net/pkt_sched.h> | |
27 | ||
28 | /* Network Emulation Queuing algorithm. | |
29 | ==================================== | |
30 | ||
31 | Sources: [1] Mark Carson, Darrin Santay, "NIST Net - A Linux-based | |
32 | Network Emulation Tool | |
33 | [2] Luigi Rizzo, DummyNet for FreeBSD | |
34 | ||
35 | ---------------------------------------------------------------- | |
36 | ||
37 | This started out as a simple way to delay outgoing packets to | |
38 | test TCP but has grown to include most of the functionality | |
39 | of a full blown network emulator like NISTnet. It can delay | |
40 | packets and add random jitter (and correlation). The random | |
41 | distribution can be loaded from a table as well to provide | |
42 | normal, Pareto, or experimental curves. Packet loss, | |
43 | duplication, and reordering can also be emulated. | |
44 | ||
45 | This qdisc does not do classification that can be handled in | |
46 | layering other disciplines. It does not need to do bandwidth | |
47 | control either since that can be handled by using token | |
48 | bucket or other rate control. | |
49 | ||
50 | The simulator is limited by the Linux timer resolution | |
51 | and will create packet bursts on the HZ boundary (1ms). | |
52 | */ | |
53 | ||
54 | struct netem_sched_data { | |
55 | struct Qdisc *qdisc; | |
1da177e4 LT |
56 | struct timer_list timer; |
57 | ||
58 | u32 latency; | |
59 | u32 loss; | |
60 | u32 limit; | |
61 | u32 counter; | |
62 | u32 gap; | |
63 | u32 jitter; | |
64 | u32 duplicate; | |
65 | ||
66 | struct crndstate { | |
67 | unsigned long last; | |
68 | unsigned long rho; | |
69 | } delay_cor, loss_cor, dup_cor; | |
70 | ||
71 | struct disttable { | |
72 | u32 size; | |
73 | s16 table[0]; | |
74 | } *delay_dist; | |
75 | }; | |
76 | ||
77 | /* Time stamp put into socket buffer control block */ | |
78 | struct netem_skb_cb { | |
79 | psched_time_t time_to_send; | |
80 | }; | |
81 | ||
82 | /* init_crandom - initialize correlated random number generator | |
83 | * Use entropy source for initial seed. | |
84 | */ | |
85 | static void init_crandom(struct crndstate *state, unsigned long rho) | |
86 | { | |
87 | state->rho = rho; | |
88 | state->last = net_random(); | |
89 | } | |
90 | ||
91 | /* get_crandom - correlated random number generator | |
92 | * Next number depends on last value. | |
93 | * rho is scaled to avoid floating point. | |
94 | */ | |
95 | static unsigned long get_crandom(struct crndstate *state) | |
96 | { | |
97 | u64 value, rho; | |
98 | unsigned long answer; | |
99 | ||
100 | if (state->rho == 0) /* no correllation */ | |
101 | return net_random(); | |
102 | ||
103 | value = net_random(); | |
104 | rho = (u64)state->rho + 1; | |
105 | answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32; | |
106 | state->last = answer; | |
107 | return answer; | |
108 | } | |
109 | ||
110 | /* tabledist - return a pseudo-randomly distributed value with mean mu and | |
111 | * std deviation sigma. Uses table lookup to approximate the desired | |
112 | * distribution, and a uniformly-distributed pseudo-random source. | |
113 | */ | |
114 | static long tabledist(unsigned long mu, long sigma, | |
115 | struct crndstate *state, const struct disttable *dist) | |
116 | { | |
117 | long t, x; | |
118 | unsigned long rnd; | |
119 | ||
120 | if (sigma == 0) | |
121 | return mu; | |
122 | ||
123 | rnd = get_crandom(state); | |
124 | ||
125 | /* default uniform distribution */ | |
126 | if (dist == NULL) | |
127 | return (rnd % (2*sigma)) - sigma + mu; | |
128 | ||
129 | t = dist->table[rnd % dist->size]; | |
130 | x = (sigma % NETEM_DIST_SCALE) * t; | |
131 | if (x >= 0) | |
132 | x += NETEM_DIST_SCALE/2; | |
133 | else | |
134 | x -= NETEM_DIST_SCALE/2; | |
135 | ||
136 | return x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu; | |
137 | } | |
138 | ||
0afb51e7 SH |
139 | /* |
140 | * Insert one skb into qdisc. | |
141 | * Note: parent depends on return value to account for queue length. | |
142 | * NET_XMIT_DROP: queue length didn't change. | |
143 | * NET_XMIT_SUCCESS: one skb was queued. | |
144 | */ | |
1da177e4 LT |
145 | static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch) |
146 | { | |
147 | struct netem_sched_data *q = qdisc_priv(sch); | |
0f9f32ac | 148 | struct netem_skb_cb *cb = (struct netem_skb_cb *)skb->cb; |
0afb51e7 | 149 | struct sk_buff *skb2; |
1da177e4 | 150 | int ret; |
0afb51e7 | 151 | int count = 1; |
1da177e4 | 152 | |
771018e7 | 153 | pr_debug("netem_enqueue skb=%p\n", skb); |
1da177e4 | 154 | |
0afb51e7 SH |
155 | /* Random duplication */ |
156 | if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor)) | |
157 | ++count; | |
158 | ||
1da177e4 | 159 | /* Random packet drop 0 => none, ~0 => all */ |
0afb51e7 SH |
160 | if (q->loss && q->loss >= get_crandom(&q->loss_cor)) |
161 | --count; | |
162 | ||
163 | if (count == 0) { | |
1da177e4 LT |
164 | sch->qstats.drops++; |
165 | kfree_skb(skb); | |
0afb51e7 | 166 | return NET_XMIT_DROP; |
1da177e4 LT |
167 | } |
168 | ||
0afb51e7 SH |
169 | /* |
170 | * If we need to duplicate packet, then re-insert at top of the | |
171 | * qdisc tree, since parent queuer expects that only one | |
172 | * skb will be queued. | |
173 | */ | |
174 | if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) { | |
175 | struct Qdisc *rootq = sch->dev->qdisc; | |
176 | u32 dupsave = q->duplicate; /* prevent duplicating a dup... */ | |
177 | q->duplicate = 0; | |
178 | ||
179 | rootq->enqueue(skb2, rootq); | |
180 | q->duplicate = dupsave; | |
1da177e4 LT |
181 | } |
182 | ||
0f9f32ac SH |
183 | /* |
184 | * Do re-ordering by putting one out of N packets at the front | |
185 | * of the queue. | |
186 | * gap == 0 is special case for no-reordering. | |
1da177e4 | 187 | */ |
0f9f32ac SH |
188 | if (q->gap == 0 || q->counter != q->gap) { |
189 | psched_time_t now; | |
190 | PSCHED_GET_TIME(now); | |
191 | PSCHED_TADD2(now, | |
192 | tabledist(q->latency, q->jitter, &q->delay_cor, q->delay_dist), | |
193 | cb->time_to_send); | |
194 | ||
1da177e4 LT |
195 | ++q->counter; |
196 | ret = q->qdisc->enqueue(skb, q->qdisc); | |
197 | } else { | |
198 | q->counter = 0; | |
0f9f32ac SH |
199 | PSCHED_GET_TIME(cb->time_to_send); |
200 | ret = q->qdisc->ops->requeue(skb, q->qdisc); | |
1da177e4 LT |
201 | } |
202 | ||
203 | if (likely(ret == NET_XMIT_SUCCESS)) { | |
204 | sch->q.qlen++; | |
205 | sch->bstats.bytes += skb->len; | |
206 | sch->bstats.packets++; | |
207 | } else | |
208 | sch->qstats.drops++; | |
209 | ||
d5d75cd6 | 210 | pr_debug("netem: enqueue ret %d\n", ret); |
1da177e4 LT |
211 | return ret; |
212 | } | |
213 | ||
214 | /* Requeue packets but don't change time stamp */ | |
215 | static int netem_requeue(struct sk_buff *skb, struct Qdisc *sch) | |
216 | { | |
217 | struct netem_sched_data *q = qdisc_priv(sch); | |
218 | int ret; | |
219 | ||
220 | if ((ret = q->qdisc->ops->requeue(skb, q->qdisc)) == 0) { | |
221 | sch->q.qlen++; | |
222 | sch->qstats.requeues++; | |
223 | } | |
224 | ||
225 | return ret; | |
226 | } | |
227 | ||
228 | static unsigned int netem_drop(struct Qdisc* sch) | |
229 | { | |
230 | struct netem_sched_data *q = qdisc_priv(sch); | |
231 | unsigned int len; | |
232 | ||
233 | if ((len = q->qdisc->ops->drop(q->qdisc)) != 0) { | |
234 | sch->q.qlen--; | |
235 | sch->qstats.drops++; | |
236 | } | |
237 | return len; | |
238 | } | |
239 | ||
1da177e4 LT |
240 | static struct sk_buff *netem_dequeue(struct Qdisc *sch) |
241 | { | |
242 | struct netem_sched_data *q = qdisc_priv(sch); | |
243 | struct sk_buff *skb; | |
244 | ||
245 | skb = q->qdisc->dequeue(q->qdisc); | |
771018e7 | 246 | if (skb) { |
0f9f32ac SH |
247 | const struct netem_skb_cb *cb |
248 | = (const struct netem_skb_cb *)skb->cb; | |
249 | psched_time_t now; | |
250 | long delay; | |
251 | ||
252 | /* if more time remaining? */ | |
253 | PSCHED_GET_TIME(now); | |
254 | delay = PSCHED_US2JIFFIE(PSCHED_TDIFF(cb->time_to_send, now)); | |
255 | pr_debug("netem_run: skb=%p delay=%ld\n", skb, delay); | |
256 | if (delay <= 0) { | |
257 | pr_debug("netem_dequeue: return skb=%p\n", skb); | |
258 | sch->q.qlen--; | |
259 | sch->flags &= ~TCQ_F_THROTTLED; | |
260 | return skb; | |
261 | } | |
262 | ||
263 | mod_timer(&q->timer, jiffies + delay); | |
771018e7 | 264 | sch->flags |= TCQ_F_THROTTLED; |
771018e7 | 265 | |
0f9f32ac SH |
266 | if (q->qdisc->ops->requeue(skb, q->qdisc) != 0) |
267 | sch->qstats.drops++; | |
268 | } | |
269 | ||
270 | return NULL; | |
1da177e4 LT |
271 | } |
272 | ||
273 | static void netem_watchdog(unsigned long arg) | |
274 | { | |
275 | struct Qdisc *sch = (struct Qdisc *)arg; | |
1da177e4 | 276 | |
771018e7 SH |
277 | pr_debug("netem_watchdog qlen=%d\n", sch->q.qlen); |
278 | sch->flags &= ~TCQ_F_THROTTLED; | |
279 | netif_schedule(sch->dev); | |
1da177e4 LT |
280 | } |
281 | ||
282 | static void netem_reset(struct Qdisc *sch) | |
283 | { | |
284 | struct netem_sched_data *q = qdisc_priv(sch); | |
285 | ||
286 | qdisc_reset(q->qdisc); | |
1da177e4 | 287 | sch->q.qlen = 0; |
771018e7 | 288 | sch->flags &= ~TCQ_F_THROTTLED; |
1da177e4 LT |
289 | del_timer_sync(&q->timer); |
290 | } | |
291 | ||
292 | static int set_fifo_limit(struct Qdisc *q, int limit) | |
293 | { | |
294 | struct rtattr *rta; | |
295 | int ret = -ENOMEM; | |
296 | ||
297 | rta = kmalloc(RTA_LENGTH(sizeof(struct tc_fifo_qopt)), GFP_KERNEL); | |
298 | if (rta) { | |
299 | rta->rta_type = RTM_NEWQDISC; | |
300 | rta->rta_len = RTA_LENGTH(sizeof(struct tc_fifo_qopt)); | |
301 | ((struct tc_fifo_qopt *)RTA_DATA(rta))->limit = limit; | |
302 | ||
303 | ret = q->ops->change(q, rta); | |
304 | kfree(rta); | |
305 | } | |
306 | return ret; | |
307 | } | |
308 | ||
309 | /* | |
310 | * Distribution data is a variable size payload containing | |
311 | * signed 16 bit values. | |
312 | */ | |
313 | static int get_dist_table(struct Qdisc *sch, const struct rtattr *attr) | |
314 | { | |
315 | struct netem_sched_data *q = qdisc_priv(sch); | |
316 | unsigned long n = RTA_PAYLOAD(attr)/sizeof(__s16); | |
317 | const __s16 *data = RTA_DATA(attr); | |
318 | struct disttable *d; | |
319 | int i; | |
320 | ||
321 | if (n > 65536) | |
322 | return -EINVAL; | |
323 | ||
324 | d = kmalloc(sizeof(*d) + n*sizeof(d->table[0]), GFP_KERNEL); | |
325 | if (!d) | |
326 | return -ENOMEM; | |
327 | ||
328 | d->size = n; | |
329 | for (i = 0; i < n; i++) | |
330 | d->table[i] = data[i]; | |
331 | ||
332 | spin_lock_bh(&sch->dev->queue_lock); | |
333 | d = xchg(&q->delay_dist, d); | |
334 | spin_unlock_bh(&sch->dev->queue_lock); | |
335 | ||
336 | kfree(d); | |
337 | return 0; | |
338 | } | |
339 | ||
340 | static int get_correlation(struct Qdisc *sch, const struct rtattr *attr) | |
341 | { | |
342 | struct netem_sched_data *q = qdisc_priv(sch); | |
343 | const struct tc_netem_corr *c = RTA_DATA(attr); | |
344 | ||
345 | if (RTA_PAYLOAD(attr) != sizeof(*c)) | |
346 | return -EINVAL; | |
347 | ||
348 | init_crandom(&q->delay_cor, c->delay_corr); | |
349 | init_crandom(&q->loss_cor, c->loss_corr); | |
350 | init_crandom(&q->dup_cor, c->dup_corr); | |
351 | return 0; | |
352 | } | |
353 | ||
354 | static int netem_change(struct Qdisc *sch, struct rtattr *opt) | |
355 | { | |
356 | struct netem_sched_data *q = qdisc_priv(sch); | |
357 | struct tc_netem_qopt *qopt; | |
358 | int ret; | |
359 | ||
360 | if (opt == NULL || RTA_PAYLOAD(opt) < sizeof(*qopt)) | |
361 | return -EINVAL; | |
362 | ||
363 | qopt = RTA_DATA(opt); | |
364 | ret = set_fifo_limit(q->qdisc, qopt->limit); | |
365 | if (ret) { | |
366 | pr_debug("netem: can't set fifo limit\n"); | |
367 | return ret; | |
368 | } | |
369 | ||
370 | q->latency = qopt->latency; | |
371 | q->jitter = qopt->jitter; | |
372 | q->limit = qopt->limit; | |
373 | q->gap = qopt->gap; | |
374 | q->loss = qopt->loss; | |
375 | q->duplicate = qopt->duplicate; | |
376 | ||
377 | /* Handle nested options after initial queue options. | |
378 | * Should have put all options in nested format but too late now. | |
379 | */ | |
380 | if (RTA_PAYLOAD(opt) > sizeof(*qopt)) { | |
381 | struct rtattr *tb[TCA_NETEM_MAX]; | |
382 | if (rtattr_parse(tb, TCA_NETEM_MAX, | |
383 | RTA_DATA(opt) + sizeof(*qopt), | |
384 | RTA_PAYLOAD(opt) - sizeof(*qopt))) | |
385 | return -EINVAL; | |
386 | ||
387 | if (tb[TCA_NETEM_CORR-1]) { | |
388 | ret = get_correlation(sch, tb[TCA_NETEM_CORR-1]); | |
389 | if (ret) | |
390 | return ret; | |
391 | } | |
392 | ||
393 | if (tb[TCA_NETEM_DELAY_DIST-1]) { | |
394 | ret = get_dist_table(sch, tb[TCA_NETEM_DELAY_DIST-1]); | |
395 | if (ret) | |
396 | return ret; | |
397 | } | |
398 | } | |
399 | ||
400 | ||
401 | return 0; | |
402 | } | |
403 | ||
404 | static int netem_init(struct Qdisc *sch, struct rtattr *opt) | |
405 | { | |
406 | struct netem_sched_data *q = qdisc_priv(sch); | |
407 | int ret; | |
408 | ||
409 | if (!opt) | |
410 | return -EINVAL; | |
411 | ||
1da177e4 LT |
412 | init_timer(&q->timer); |
413 | q->timer.function = netem_watchdog; | |
414 | q->timer.data = (unsigned long) sch; | |
415 | q->counter = 0; | |
416 | ||
417 | q->qdisc = qdisc_create_dflt(sch->dev, &pfifo_qdisc_ops); | |
418 | if (!q->qdisc) { | |
419 | pr_debug("netem: qdisc create failed\n"); | |
420 | return -ENOMEM; | |
421 | } | |
422 | ||
423 | ret = netem_change(sch, opt); | |
424 | if (ret) { | |
425 | pr_debug("netem: change failed\n"); | |
426 | qdisc_destroy(q->qdisc); | |
427 | } | |
428 | return ret; | |
429 | } | |
430 | ||
431 | static void netem_destroy(struct Qdisc *sch) | |
432 | { | |
433 | struct netem_sched_data *q = qdisc_priv(sch); | |
434 | ||
435 | del_timer_sync(&q->timer); | |
436 | qdisc_destroy(q->qdisc); | |
437 | kfree(q->delay_dist); | |
438 | } | |
439 | ||
440 | static int netem_dump(struct Qdisc *sch, struct sk_buff *skb) | |
441 | { | |
442 | const struct netem_sched_data *q = qdisc_priv(sch); | |
443 | unsigned char *b = skb->tail; | |
444 | struct rtattr *rta = (struct rtattr *) b; | |
445 | struct tc_netem_qopt qopt; | |
446 | struct tc_netem_corr cor; | |
447 | ||
448 | qopt.latency = q->latency; | |
449 | qopt.jitter = q->jitter; | |
450 | qopt.limit = q->limit; | |
451 | qopt.loss = q->loss; | |
452 | qopt.gap = q->gap; | |
453 | qopt.duplicate = q->duplicate; | |
454 | RTA_PUT(skb, TCA_OPTIONS, sizeof(qopt), &qopt); | |
455 | ||
456 | cor.delay_corr = q->delay_cor.rho; | |
457 | cor.loss_corr = q->loss_cor.rho; | |
458 | cor.dup_corr = q->dup_cor.rho; | |
459 | RTA_PUT(skb, TCA_NETEM_CORR, sizeof(cor), &cor); | |
460 | rta->rta_len = skb->tail - b; | |
461 | ||
462 | return skb->len; | |
463 | ||
464 | rtattr_failure: | |
465 | skb_trim(skb, b - skb->data); | |
466 | return -1; | |
467 | } | |
468 | ||
469 | static int netem_dump_class(struct Qdisc *sch, unsigned long cl, | |
470 | struct sk_buff *skb, struct tcmsg *tcm) | |
471 | { | |
472 | struct netem_sched_data *q = qdisc_priv(sch); | |
473 | ||
474 | if (cl != 1) /* only one class */ | |
475 | return -ENOENT; | |
476 | ||
477 | tcm->tcm_handle |= TC_H_MIN(1); | |
478 | tcm->tcm_info = q->qdisc->handle; | |
479 | ||
480 | return 0; | |
481 | } | |
482 | ||
483 | static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, | |
484 | struct Qdisc **old) | |
485 | { | |
486 | struct netem_sched_data *q = qdisc_priv(sch); | |
487 | ||
488 | if (new == NULL) | |
489 | new = &noop_qdisc; | |
490 | ||
491 | sch_tree_lock(sch); | |
492 | *old = xchg(&q->qdisc, new); | |
493 | qdisc_reset(*old); | |
494 | sch->q.qlen = 0; | |
495 | sch_tree_unlock(sch); | |
496 | ||
497 | return 0; | |
498 | } | |
499 | ||
500 | static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg) | |
501 | { | |
502 | struct netem_sched_data *q = qdisc_priv(sch); | |
503 | return q->qdisc; | |
504 | } | |
505 | ||
506 | static unsigned long netem_get(struct Qdisc *sch, u32 classid) | |
507 | { | |
508 | return 1; | |
509 | } | |
510 | ||
511 | static void netem_put(struct Qdisc *sch, unsigned long arg) | |
512 | { | |
513 | } | |
514 | ||
515 | static int netem_change_class(struct Qdisc *sch, u32 classid, u32 parentid, | |
516 | struct rtattr **tca, unsigned long *arg) | |
517 | { | |
518 | return -ENOSYS; | |
519 | } | |
520 | ||
521 | static int netem_delete(struct Qdisc *sch, unsigned long arg) | |
522 | { | |
523 | return -ENOSYS; | |
524 | } | |
525 | ||
526 | static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker) | |
527 | { | |
528 | if (!walker->stop) { | |
529 | if (walker->count >= walker->skip) | |
530 | if (walker->fn(sch, 1, walker) < 0) { | |
531 | walker->stop = 1; | |
532 | return; | |
533 | } | |
534 | walker->count++; | |
535 | } | |
536 | } | |
537 | ||
538 | static struct tcf_proto **netem_find_tcf(struct Qdisc *sch, unsigned long cl) | |
539 | { | |
540 | return NULL; | |
541 | } | |
542 | ||
543 | static struct Qdisc_class_ops netem_class_ops = { | |
544 | .graft = netem_graft, | |
545 | .leaf = netem_leaf, | |
546 | .get = netem_get, | |
547 | .put = netem_put, | |
548 | .change = netem_change_class, | |
549 | .delete = netem_delete, | |
550 | .walk = netem_walk, | |
551 | .tcf_chain = netem_find_tcf, | |
552 | .dump = netem_dump_class, | |
553 | }; | |
554 | ||
555 | static struct Qdisc_ops netem_qdisc_ops = { | |
556 | .id = "netem", | |
557 | .cl_ops = &netem_class_ops, | |
558 | .priv_size = sizeof(struct netem_sched_data), | |
559 | .enqueue = netem_enqueue, | |
560 | .dequeue = netem_dequeue, | |
561 | .requeue = netem_requeue, | |
562 | .drop = netem_drop, | |
563 | .init = netem_init, | |
564 | .reset = netem_reset, | |
565 | .destroy = netem_destroy, | |
566 | .change = netem_change, | |
567 | .dump = netem_dump, | |
568 | .owner = THIS_MODULE, | |
569 | }; | |
570 | ||
571 | ||
572 | static int __init netem_module_init(void) | |
573 | { | |
574 | return register_qdisc(&netem_qdisc_ops); | |
575 | } | |
576 | static void __exit netem_module_exit(void) | |
577 | { | |
578 | unregister_qdisc(&netem_qdisc_ops); | |
579 | } | |
580 | module_init(netem_module_init) | |
581 | module_exit(netem_module_exit) | |
582 | MODULE_LICENSE("GPL"); |