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1 /*
2 * net/sched/sch_gred.c Generic Random Early Detection queue.
3 *
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
9 *
10 * Authors: J Hadi Salim (hadi@cyberus.ca) 1998-2002
11 *
12 * 991129: - Bug fix with grio mode
13 * - a better sing. AvgQ mode with Grio(WRED)
14 * - A finer grained VQ dequeue based on sugestion
15 * from Ren Liu
16 * - More error checks
17 *
18 * For all the glorious comments look at include/net/red.h
19 */
20
21 #include <linux/slab.h>
22 #include <linux/module.h>
23 #include <linux/types.h>
24 #include <linux/kernel.h>
25 #include <linux/skbuff.h>
26 #include <net/pkt_sched.h>
27 #include <net/red.h>
28
29 #define GRED_DEF_PRIO (MAX_DPs / 2)
30 #define GRED_VQ_MASK (MAX_DPs - 1)
31
32 struct gred_sched_data;
33 struct gred_sched;
34
35 struct gred_sched_data {
36 u32 limit; /* HARD maximal queue length */
37 u32 DP; /* the drop parameters */
38 u32 bytesin; /* bytes seen on virtualQ so far*/
39 u32 packetsin; /* packets seen on virtualQ so far*/
40 u32 backlog; /* bytes on the virtualQ */
41 u8 prio; /* the prio of this vq */
42
43 struct red_parms parms;
44 struct red_vars vars;
45 struct red_stats stats;
46 };
47
48 enum {
49 GRED_WRED_MODE = 1,
50 GRED_RIO_MODE,
51 };
52
53 struct gred_sched {
54 struct gred_sched_data *tab[MAX_DPs];
55 unsigned long flags;
56 u32 red_flags;
57 u32 DPs;
58 u32 def;
59 struct red_vars wred_set;
60 };
61
62 static inline int gred_wred_mode(struct gred_sched *table)
63 {
64 return test_bit(GRED_WRED_MODE, &table->flags);
65 }
66
67 static inline void gred_enable_wred_mode(struct gred_sched *table)
68 {
69 __set_bit(GRED_WRED_MODE, &table->flags);
70 }
71
72 static inline void gred_disable_wred_mode(struct gred_sched *table)
73 {
74 __clear_bit(GRED_WRED_MODE, &table->flags);
75 }
76
77 static inline int gred_rio_mode(struct gred_sched *table)
78 {
79 return test_bit(GRED_RIO_MODE, &table->flags);
80 }
81
82 static inline void gred_enable_rio_mode(struct gred_sched *table)
83 {
84 __set_bit(GRED_RIO_MODE, &table->flags);
85 }
86
87 static inline void gred_disable_rio_mode(struct gred_sched *table)
88 {
89 __clear_bit(GRED_RIO_MODE, &table->flags);
90 }
91
92 static inline int gred_wred_mode_check(struct Qdisc *sch)
93 {
94 struct gred_sched *table = qdisc_priv(sch);
95 int i;
96
97 /* Really ugly O(n^2) but shouldn't be necessary too frequent. */
98 for (i = 0; i < table->DPs; i++) {
99 struct gred_sched_data *q = table->tab[i];
100 int n;
101
102 if (q == NULL)
103 continue;
104
105 for (n = i + 1; n < table->DPs; n++)
106 if (table->tab[n] && table->tab[n]->prio == q->prio)
107 return 1;
108 }
109
110 return 0;
111 }
112
113 static inline unsigned int gred_backlog(struct gred_sched *table,
114 struct gred_sched_data *q,
115 struct Qdisc *sch)
116 {
117 if (gred_wred_mode(table))
118 return sch->qstats.backlog;
119 else
120 return q->backlog;
121 }
122
123 static inline u16 tc_index_to_dp(struct sk_buff *skb)
124 {
125 return skb->tc_index & GRED_VQ_MASK;
126 }
127
128 static inline void gred_load_wred_set(const struct gred_sched *table,
129 struct gred_sched_data *q)
130 {
131 q->vars.qavg = table->wred_set.qavg;
132 q->vars.qidlestart = table->wred_set.qidlestart;
133 }
134
135 static inline void gred_store_wred_set(struct gred_sched *table,
136 struct gred_sched_data *q)
137 {
138 table->wred_set.qavg = q->vars.qavg;
139 table->wred_set.qidlestart = q->vars.qidlestart;
140 }
141
142 static inline int gred_use_ecn(struct gred_sched *t)
143 {
144 return t->red_flags & TC_RED_ECN;
145 }
146
147 static inline int gred_use_harddrop(struct gred_sched *t)
148 {
149 return t->red_flags & TC_RED_HARDDROP;
150 }
151
152 static int gred_enqueue(struct sk_buff *skb, struct Qdisc *sch,
153 struct sk_buff **to_free)
154 {
155 struct gred_sched_data *q = NULL;
156 struct gred_sched *t = qdisc_priv(sch);
157 unsigned long qavg = 0;
158 u16 dp = tc_index_to_dp(skb);
159
160 if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
161 dp = t->def;
162
163 q = t->tab[dp];
164 if (!q) {
165 /* Pass through packets not assigned to a DP
166 * if no default DP has been configured. This
167 * allows for DP flows to be left untouched.
168 */
169 if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <=
170 sch->limit))
171 return qdisc_enqueue_tail(skb, sch);
172 else
173 goto drop;
174 }
175
176 /* fix tc_index? --could be controversial but needed for
177 requeueing */
178 skb->tc_index = (skb->tc_index & ~GRED_VQ_MASK) | dp;
179 }
180
181 /* sum up all the qaves of prios < ours to get the new qave */
182 if (!gred_wred_mode(t) && gred_rio_mode(t)) {
183 int i;
184
185 for (i = 0; i < t->DPs; i++) {
186 if (t->tab[i] && t->tab[i]->prio < q->prio &&
187 !red_is_idling(&t->tab[i]->vars))
188 qavg += t->tab[i]->vars.qavg;
189 }
190
191 }
192
193 q->packetsin++;
194 q->bytesin += qdisc_pkt_len(skb);
195
196 if (gred_wred_mode(t))
197 gred_load_wred_set(t, q);
198
199 q->vars.qavg = red_calc_qavg(&q->parms,
200 &q->vars,
201 gred_backlog(t, q, sch));
202
203 if (red_is_idling(&q->vars))
204 red_end_of_idle_period(&q->vars);
205
206 if (gred_wred_mode(t))
207 gred_store_wred_set(t, q);
208
209 switch (red_action(&q->parms, &q->vars, q->vars.qavg + qavg)) {
210 case RED_DONT_MARK:
211 break;
212
213 case RED_PROB_MARK:
214 qdisc_qstats_overlimit(sch);
215 if (!gred_use_ecn(t) || !INET_ECN_set_ce(skb)) {
216 q->stats.prob_drop++;
217 goto congestion_drop;
218 }
219
220 q->stats.prob_mark++;
221 break;
222
223 case RED_HARD_MARK:
224 qdisc_qstats_overlimit(sch);
225 if (gred_use_harddrop(t) || !gred_use_ecn(t) ||
226 !INET_ECN_set_ce(skb)) {
227 q->stats.forced_drop++;
228 goto congestion_drop;
229 }
230 q->stats.forced_mark++;
231 break;
232 }
233
234 if (gred_backlog(t, q, sch) + qdisc_pkt_len(skb) <= q->limit) {
235 q->backlog += qdisc_pkt_len(skb);
236 return qdisc_enqueue_tail(skb, sch);
237 }
238
239 q->stats.pdrop++;
240 drop:
241 return qdisc_drop(skb, sch, to_free);
242
243 congestion_drop:
244 qdisc_drop(skb, sch, to_free);
245 return NET_XMIT_CN;
246 }
247
248 static struct sk_buff *gred_dequeue(struct Qdisc *sch)
249 {
250 struct sk_buff *skb;
251 struct gred_sched *t = qdisc_priv(sch);
252
253 skb = qdisc_dequeue_head(sch);
254
255 if (skb) {
256 struct gred_sched_data *q;
257 u16 dp = tc_index_to_dp(skb);
258
259 if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
260 net_warn_ratelimited("GRED: Unable to relocate VQ 0x%x after dequeue, screwing up backlog\n",
261 tc_index_to_dp(skb));
262 } else {
263 q->backlog -= qdisc_pkt_len(skb);
264
265 if (gred_wred_mode(t)) {
266 if (!sch->qstats.backlog)
267 red_start_of_idle_period(&t->wred_set);
268 } else {
269 if (!q->backlog)
270 red_start_of_idle_period(&q->vars);
271 }
272 }
273
274 return skb;
275 }
276
277 return NULL;
278 }
279
280 static void gred_reset(struct Qdisc *sch)
281 {
282 int i;
283 struct gred_sched *t = qdisc_priv(sch);
284
285 qdisc_reset_queue(sch);
286
287 for (i = 0; i < t->DPs; i++) {
288 struct gred_sched_data *q = t->tab[i];
289
290 if (!q)
291 continue;
292
293 red_restart(&q->vars);
294 q->backlog = 0;
295 }
296 }
297
298 static inline void gred_destroy_vq(struct gred_sched_data *q)
299 {
300 kfree(q);
301 }
302
303 static inline int gred_change_table_def(struct Qdisc *sch, struct nlattr *dps)
304 {
305 struct gred_sched *table = qdisc_priv(sch);
306 struct tc_gred_sopt *sopt;
307 int i;
308
309 if (dps == NULL)
310 return -EINVAL;
311
312 sopt = nla_data(dps);
313
314 if (sopt->DPs > MAX_DPs || sopt->DPs == 0 || sopt->def_DP >= sopt->DPs)
315 return -EINVAL;
316
317 sch_tree_lock(sch);
318 table->DPs = sopt->DPs;
319 table->def = sopt->def_DP;
320 table->red_flags = sopt->flags;
321
322 /*
323 * Every entry point to GRED is synchronized with the above code
324 * and the DP is checked against DPs, i.e. shadowed VQs can no
325 * longer be found so we can unlock right here.
326 */
327 sch_tree_unlock(sch);
328
329 if (sopt->grio) {
330 gred_enable_rio_mode(table);
331 gred_disable_wred_mode(table);
332 if (gred_wred_mode_check(sch))
333 gred_enable_wred_mode(table);
334 } else {
335 gred_disable_rio_mode(table);
336 gred_disable_wred_mode(table);
337 }
338
339 for (i = table->DPs; i < MAX_DPs; i++) {
340 if (table->tab[i]) {
341 pr_warn("GRED: Warning: Destroying shadowed VQ 0x%x\n",
342 i);
343 gred_destroy_vq(table->tab[i]);
344 table->tab[i] = NULL;
345 }
346 }
347
348 return 0;
349 }
350
351 static inline int gred_change_vq(struct Qdisc *sch, int dp,
352 struct tc_gred_qopt *ctl, int prio,
353 u8 *stab, u32 max_P,
354 struct gred_sched_data **prealloc)
355 {
356 struct gred_sched *table = qdisc_priv(sch);
357 struct gred_sched_data *q = table->tab[dp];
358
359 if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog))
360 return -EINVAL;
361
362 if (!q) {
363 table->tab[dp] = q = *prealloc;
364 *prealloc = NULL;
365 if (!q)
366 return -ENOMEM;
367 }
368
369 q->DP = dp;
370 q->prio = prio;
371 if (ctl->limit > sch->limit)
372 q->limit = sch->limit;
373 else
374 q->limit = ctl->limit;
375
376 if (q->backlog == 0)
377 red_end_of_idle_period(&q->vars);
378
379 red_set_parms(&q->parms,
380 ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Plog,
381 ctl->Scell_log, stab, max_P);
382 red_set_vars(&q->vars);
383 return 0;
384 }
385
386 static const struct nla_policy gred_policy[TCA_GRED_MAX + 1] = {
387 [TCA_GRED_PARMS] = { .len = sizeof(struct tc_gred_qopt) },
388 [TCA_GRED_STAB] = { .len = 256 },
389 [TCA_GRED_DPS] = { .len = sizeof(struct tc_gred_sopt) },
390 [TCA_GRED_MAX_P] = { .type = NLA_U32 },
391 [TCA_GRED_LIMIT] = { .type = NLA_U32 },
392 };
393
394 static int gred_change(struct Qdisc *sch, struct nlattr *opt)
395 {
396 struct gred_sched *table = qdisc_priv(sch);
397 struct tc_gred_qopt *ctl;
398 struct nlattr *tb[TCA_GRED_MAX + 1];
399 int err, prio = GRED_DEF_PRIO;
400 u8 *stab;
401 u32 max_P;
402 struct gred_sched_data *prealloc;
403
404 if (opt == NULL)
405 return -EINVAL;
406
407 err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy, NULL);
408 if (err < 0)
409 return err;
410
411 if (tb[TCA_GRED_PARMS] == NULL && tb[TCA_GRED_STAB] == NULL) {
412 if (tb[TCA_GRED_LIMIT] != NULL)
413 sch->limit = nla_get_u32(tb[TCA_GRED_LIMIT]);
414 return gred_change_table_def(sch, opt);
415 }
416
417 if (tb[TCA_GRED_PARMS] == NULL ||
418 tb[TCA_GRED_STAB] == NULL ||
419 tb[TCA_GRED_LIMIT] != NULL)
420 return -EINVAL;
421
422 max_P = tb[TCA_GRED_MAX_P] ? nla_get_u32(tb[TCA_GRED_MAX_P]) : 0;
423
424 err = -EINVAL;
425 ctl = nla_data(tb[TCA_GRED_PARMS]);
426 stab = nla_data(tb[TCA_GRED_STAB]);
427
428 if (ctl->DP >= table->DPs)
429 goto errout;
430
431 if (gred_rio_mode(table)) {
432 if (ctl->prio == 0) {
433 int def_prio = GRED_DEF_PRIO;
434
435 if (table->tab[table->def])
436 def_prio = table->tab[table->def]->prio;
437
438 printk(KERN_DEBUG "GRED: DP %u does not have a prio "
439 "setting default to %d\n", ctl->DP, def_prio);
440
441 prio = def_prio;
442 } else
443 prio = ctl->prio;
444 }
445
446 prealloc = kzalloc(sizeof(*prealloc), GFP_KERNEL);
447 sch_tree_lock(sch);
448
449 err = gred_change_vq(sch, ctl->DP, ctl, prio, stab, max_P, &prealloc);
450 if (err < 0)
451 goto errout_locked;
452
453 if (gred_rio_mode(table)) {
454 gred_disable_wred_mode(table);
455 if (gred_wred_mode_check(sch))
456 gred_enable_wred_mode(table);
457 }
458
459 err = 0;
460
461 errout_locked:
462 sch_tree_unlock(sch);
463 kfree(prealloc);
464 errout:
465 return err;
466 }
467
468 static int gred_init(struct Qdisc *sch, struct nlattr *opt)
469 {
470 struct nlattr *tb[TCA_GRED_MAX + 1];
471 int err;
472
473 if (opt == NULL)
474 return -EINVAL;
475
476 err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy, NULL);
477 if (err < 0)
478 return err;
479
480 if (tb[TCA_GRED_PARMS] || tb[TCA_GRED_STAB])
481 return -EINVAL;
482
483 if (tb[TCA_GRED_LIMIT])
484 sch->limit = nla_get_u32(tb[TCA_GRED_LIMIT]);
485 else
486 sch->limit = qdisc_dev(sch)->tx_queue_len
487 * psched_mtu(qdisc_dev(sch));
488
489 return gred_change_table_def(sch, tb[TCA_GRED_DPS]);
490 }
491
492 static int gred_dump(struct Qdisc *sch, struct sk_buff *skb)
493 {
494 struct gred_sched *table = qdisc_priv(sch);
495 struct nlattr *parms, *opts = NULL;
496 int i;
497 u32 max_p[MAX_DPs];
498 struct tc_gred_sopt sopt = {
499 .DPs = table->DPs,
500 .def_DP = table->def,
501 .grio = gred_rio_mode(table),
502 .flags = table->red_flags,
503 };
504
505 opts = nla_nest_start(skb, TCA_OPTIONS);
506 if (opts == NULL)
507 goto nla_put_failure;
508 if (nla_put(skb, TCA_GRED_DPS, sizeof(sopt), &sopt))
509 goto nla_put_failure;
510
511 for (i = 0; i < MAX_DPs; i++) {
512 struct gred_sched_data *q = table->tab[i];
513
514 max_p[i] = q ? q->parms.max_P : 0;
515 }
516 if (nla_put(skb, TCA_GRED_MAX_P, sizeof(max_p), max_p))
517 goto nla_put_failure;
518
519 if (nla_put_u32(skb, TCA_GRED_LIMIT, sch->limit))
520 goto nla_put_failure;
521
522 parms = nla_nest_start(skb, TCA_GRED_PARMS);
523 if (parms == NULL)
524 goto nla_put_failure;
525
526 for (i = 0; i < MAX_DPs; i++) {
527 struct gred_sched_data *q = table->tab[i];
528 struct tc_gred_qopt opt;
529 unsigned long qavg;
530
531 memset(&opt, 0, sizeof(opt));
532
533 if (!q) {
534 /* hack -- fix at some point with proper message
535 This is how we indicate to tc that there is no VQ
536 at this DP */
537
538 opt.DP = MAX_DPs + i;
539 goto append_opt;
540 }
541
542 opt.limit = q->limit;
543 opt.DP = q->DP;
544 opt.backlog = gred_backlog(table, q, sch);
545 opt.prio = q->prio;
546 opt.qth_min = q->parms.qth_min >> q->parms.Wlog;
547 opt.qth_max = q->parms.qth_max >> q->parms.Wlog;
548 opt.Wlog = q->parms.Wlog;
549 opt.Plog = q->parms.Plog;
550 opt.Scell_log = q->parms.Scell_log;
551 opt.other = q->stats.other;
552 opt.early = q->stats.prob_drop;
553 opt.forced = q->stats.forced_drop;
554 opt.pdrop = q->stats.pdrop;
555 opt.packets = q->packetsin;
556 opt.bytesin = q->bytesin;
557
558 if (gred_wred_mode(table))
559 gred_load_wred_set(table, q);
560
561 qavg = red_calc_qavg(&q->parms, &q->vars,
562 q->vars.qavg >> q->parms.Wlog);
563 opt.qave = qavg >> q->parms.Wlog;
564
565 append_opt:
566 if (nla_append(skb, sizeof(opt), &opt) < 0)
567 goto nla_put_failure;
568 }
569
570 nla_nest_end(skb, parms);
571
572 return nla_nest_end(skb, opts);
573
574 nla_put_failure:
575 nla_nest_cancel(skb, opts);
576 return -EMSGSIZE;
577 }
578
579 static void gred_destroy(struct Qdisc *sch)
580 {
581 struct gred_sched *table = qdisc_priv(sch);
582 int i;
583
584 for (i = 0; i < table->DPs; i++) {
585 if (table->tab[i])
586 gred_destroy_vq(table->tab[i]);
587 }
588 }
589
590 static struct Qdisc_ops gred_qdisc_ops __read_mostly = {
591 .id = "gred",
592 .priv_size = sizeof(struct gred_sched),
593 .enqueue = gred_enqueue,
594 .dequeue = gred_dequeue,
595 .peek = qdisc_peek_head,
596 .init = gred_init,
597 .reset = gred_reset,
598 .destroy = gred_destroy,
599 .change = gred_change,
600 .dump = gred_dump,
601 .owner = THIS_MODULE,
602 };
603
604 static int __init gred_module_init(void)
605 {
606 return register_qdisc(&gred_qdisc_ops);
607 }
608
609 static void __exit gred_module_exit(void)
610 {
611 unregister_qdisc(&gred_qdisc_ops);
612 }
613
614 module_init(gred_module_init)
615 module_exit(gred_module_exit)
616
617 MODULE_LICENSE("GPL");
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