sch_gred.c revision 5ce2d488fe039ddd86a638496cf704df86c74eeb 
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/module.h>
22#include <linux/types.h>
23#include <linux/kernel.h>
24#include <linux/skbuff.h>
25#include <net/pkt_sched.h>
26#include <net/red.h>
27
28#define GRED_DEF_PRIO (MAX_DPs / 2)
29#define GRED_VQ_MASK (MAX_DPs - 1)
30
31struct gred_sched_data;
32struct gred_sched;
33
34struct gred_sched_data
35{
36	u32		limit;		/* HARD maximal queue length	*/
37	u32      	DP;		/* the drop pramaters */
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_stats stats;
45};
46
47enum {
48	GRED_WRED_MODE = 1,
49	GRED_RIO_MODE,
50};
51
52struct gred_sched
53{
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_parms wred_set;
60};
61
62static inline int gred_wred_mode(struct gred_sched *table)
63{
64	return test_bit(GRED_WRED_MODE, &table->flags);
65}
66
67static inline void gred_enable_wred_mode(struct gred_sched *table)
68{
69	__set_bit(GRED_WRED_MODE, &table->flags);
70}
71
72static inline void gred_disable_wred_mode(struct gred_sched *table)
73{
74	__clear_bit(GRED_WRED_MODE, &table->flags);
75}
76
77static inline int gred_rio_mode(struct gred_sched *table)
78{
79	return test_bit(GRED_RIO_MODE, &table->flags);
80}
81
82static inline void gred_enable_rio_mode(struct gred_sched *table)
83{
84	__set_bit(GRED_RIO_MODE, &table->flags);
85}
86
87static inline void gred_disable_rio_mode(struct gred_sched *table)
88{
89	__clear_bit(GRED_RIO_MODE, &table->flags);
90}
91
92static 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 = 0; n < table->DPs; n++)
106			if (table->tab[n] && table->tab[n] != q &&
107			    table->tab[n]->prio == q->prio)
108				return 1;
109	}
110
111	return 0;
112}
113
114static inline unsigned int gred_backlog(struct gred_sched *table,
115					struct gred_sched_data *q,
116					struct Qdisc *sch)
117{
118	if (gred_wred_mode(table))
119		return sch->qstats.backlog;
120	else
121		return q->backlog;
122}
123
124static inline u16 tc_index_to_dp(struct sk_buff *skb)
125{
126	return skb->tc_index & GRED_VQ_MASK;
127}
128
129static inline void gred_load_wred_set(struct gred_sched *table,
130				      struct gred_sched_data *q)
131{
132	q->parms.qavg = table->wred_set.qavg;
133	q->parms.qidlestart = table->wred_set.qidlestart;
134}
135
136static inline void gred_store_wred_set(struct gred_sched *table,
137				       struct gred_sched_data *q)
138{
139	table->wred_set.qavg = q->parms.qavg;
140}
141
142static inline int gred_use_ecn(struct gred_sched *t)
143{
144	return t->red_flags & TC_RED_ECN;
145}
146
147static inline int gred_use_harddrop(struct gred_sched *t)
148{
149	return t->red_flags & TC_RED_HARDDROP;
150}
151
152static int gred_enqueue(struct sk_buff *skb, struct Qdisc* sch)
153{
154	struct gred_sched_data *q=NULL;
155	struct gred_sched *t= qdisc_priv(sch);
156	unsigned long qavg = 0;
157	u16 dp = tc_index_to_dp(skb);
158
159	if (dp >= t->DPs  || (q = t->tab[dp]) == NULL) {
160		dp = t->def;
161
162		if ((q = t->tab[dp]) == NULL) {
163			/* Pass through packets not assigned to a DP
164			 * if no default DP has been configured. This
165			 * allows for DP flows to be left untouched.
166			 */
167			if (skb_queue_len(&sch->q) < qdisc_dev(sch)->tx_queue_len)
168				return qdisc_enqueue_tail(skb, sch);
169			else
170				goto drop;
171		}
172
173		/* fix tc_index? --could be controvesial but needed for
174		   requeueing */
175		skb->tc_index = (skb->tc_index & ~GRED_VQ_MASK) | dp;
176	}
177
178	/* sum up all the qaves of prios <= to ours to get the new qave */
179	if (!gred_wred_mode(t) && gred_rio_mode(t)) {
180		int i;
181
182		for (i = 0; i < t->DPs; i++) {
183			if (t->tab[i] && t->tab[i]->prio < q->prio &&
184			    !red_is_idling(&t->tab[i]->parms))
185				qavg +=t->tab[i]->parms.qavg;
186		}
187
188	}
189
190	q->packetsin++;
191	q->bytesin += skb->len;
192
193	if (gred_wred_mode(t))
194		gred_load_wred_set(t, q);
195
196	q->parms.qavg = red_calc_qavg(&q->parms, gred_backlog(t, q, sch));
197
198	if (red_is_idling(&q->parms))
199		red_end_of_idle_period(&q->parms);
200
201	if (gred_wred_mode(t))
202		gred_store_wred_set(t, q);
203
204	switch (red_action(&q->parms, q->parms.qavg + qavg)) {
205		case RED_DONT_MARK:
206			break;
207
208		case RED_PROB_MARK:
209			sch->qstats.overlimits++;
210			if (!gred_use_ecn(t) || !INET_ECN_set_ce(skb)) {
211				q->stats.prob_drop++;
212				goto congestion_drop;
213			}
214
215			q->stats.prob_mark++;
216			break;
217
218		case RED_HARD_MARK:
219			sch->qstats.overlimits++;
220			if (gred_use_harddrop(t) || !gred_use_ecn(t) ||
221			    !INET_ECN_set_ce(skb)) {
222				q->stats.forced_drop++;
223				goto congestion_drop;
224			}
225			q->stats.forced_mark++;
226			break;
227	}
228
229	if (q->backlog + skb->len <= q->limit) {
230		q->backlog += skb->len;
231		return qdisc_enqueue_tail(skb, sch);
232	}
233
234	q->stats.pdrop++;
235drop:
236	return qdisc_drop(skb, sch);
237
238congestion_drop:
239	qdisc_drop(skb, sch);
240	return NET_XMIT_CN;
241}
242
243static int gred_requeue(struct sk_buff *skb, struct Qdisc* sch)
244{
245	struct gred_sched *t = qdisc_priv(sch);
246	struct gred_sched_data *q;
247	u16 dp = tc_index_to_dp(skb);
248
249	if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
250		if (net_ratelimit())
251			printk(KERN_WARNING "GRED: Unable to relocate VQ 0x%x "
252			       "for requeue, screwing up backlog.\n",
253			       tc_index_to_dp(skb));
254	} else {
255		if (red_is_idling(&q->parms))
256			red_end_of_idle_period(&q->parms);
257		q->backlog += skb->len;
258	}
259
260	return qdisc_requeue(skb, sch);
261}
262
263static struct sk_buff *gred_dequeue(struct Qdisc* sch)
264{
265	struct sk_buff *skb;
266	struct gred_sched *t = qdisc_priv(sch);
267
268	skb = qdisc_dequeue_head(sch);
269
270	if (skb) {
271		struct gred_sched_data *q;
272		u16 dp = tc_index_to_dp(skb);
273
274		if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
275			if (net_ratelimit())
276				printk(KERN_WARNING "GRED: Unable to relocate "
277				       "VQ 0x%x after dequeue, screwing up "
278				       "backlog.\n", tc_index_to_dp(skb));
279		} else {
280			q->backlog -= skb->len;
281
282			if (!q->backlog && !gred_wred_mode(t))
283				red_start_of_idle_period(&q->parms);
284		}
285
286		return skb;
287	}
288
289	if (gred_wred_mode(t) && !red_is_idling(&t->wred_set))
290		red_start_of_idle_period(&t->wred_set);
291
292	return NULL;
293}
294
295static unsigned int gred_drop(struct Qdisc* sch)
296{
297	struct sk_buff *skb;
298	struct gred_sched *t = qdisc_priv(sch);
299
300	skb = qdisc_dequeue_tail(sch);
301	if (skb) {
302		unsigned int len = skb->len;
303		struct gred_sched_data *q;
304		u16 dp = tc_index_to_dp(skb);
305
306		if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
307			if (net_ratelimit())
308				printk(KERN_WARNING "GRED: Unable to relocate "
309				       "VQ 0x%x while dropping, screwing up "
310				       "backlog.\n", tc_index_to_dp(skb));
311		} else {
312			q->backlog -= len;
313			q->stats.other++;
314
315			if (!q->backlog && !gred_wred_mode(t))
316				red_start_of_idle_period(&q->parms);
317		}
318
319		qdisc_drop(skb, sch);
320		return len;
321	}
322
323	if (gred_wred_mode(t) && !red_is_idling(&t->wred_set))
324		red_start_of_idle_period(&t->wred_set);
325
326	return 0;
327
328}
329
330static void gred_reset(struct Qdisc* sch)
331{
332	int i;
333	struct gred_sched *t = qdisc_priv(sch);
334
335	qdisc_reset_queue(sch);
336
337	for (i = 0; i < t->DPs; i++) {
338		struct gred_sched_data *q = t->tab[i];
339
340		if (!q)
341			continue;
342
343		red_restart(&q->parms);
344		q->backlog = 0;
345	}
346}
347
348static inline void gred_destroy_vq(struct gred_sched_data *q)
349{
350	kfree(q);
351}
352
353static inline int gred_change_table_def(struct Qdisc *sch, struct nlattr *dps)
354{
355	struct gred_sched *table = qdisc_priv(sch);
356	struct tc_gred_sopt *sopt;
357	int i;
358
359	if (dps == NULL)
360		return -EINVAL;
361
362	sopt = nla_data(dps);
363
364	if (sopt->DPs > MAX_DPs || sopt->DPs == 0 || sopt->def_DP >= sopt->DPs)
365		return -EINVAL;
366
367	sch_tree_lock(sch);
368	table->DPs = sopt->DPs;
369	table->def = sopt->def_DP;
370	table->red_flags = sopt->flags;
371
372	/*
373	 * Every entry point to GRED is synchronized with the above code
374	 * and the DP is checked against DPs, i.e. shadowed VQs can no
375	 * longer be found so we can unlock right here.
376	 */
377	sch_tree_unlock(sch);
378
379	if (sopt->grio) {
380		gred_enable_rio_mode(table);
381		gred_disable_wred_mode(table);
382		if (gred_wred_mode_check(sch))
383			gred_enable_wred_mode(table);
384	} else {
385		gred_disable_rio_mode(table);
386		gred_disable_wred_mode(table);
387	}
388
389	for (i = table->DPs; i < MAX_DPs; i++) {
390		if (table->tab[i]) {
391			printk(KERN_WARNING "GRED: Warning: Destroying "
392			       "shadowed VQ 0x%x\n", i);
393			gred_destroy_vq(table->tab[i]);
394			table->tab[i] = NULL;
395		}
396	}
397
398	return 0;
399}
400
401static inline int gred_change_vq(struct Qdisc *sch, int dp,
402				 struct tc_gred_qopt *ctl, int prio, u8 *stab)
403{
404	struct gred_sched *table = qdisc_priv(sch);
405	struct gred_sched_data *q;
406
407	if (table->tab[dp] == NULL) {
408		table->tab[dp] = kzalloc(sizeof(*q), GFP_KERNEL);
409		if (table->tab[dp] == NULL)
410			return -ENOMEM;
411	}
412
413	q = table->tab[dp];
414	q->DP = dp;
415	q->prio = prio;
416	q->limit = ctl->limit;
417
418	if (q->backlog == 0)
419		red_end_of_idle_period(&q->parms);
420
421	red_set_parms(&q->parms,
422		      ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Plog,
423		      ctl->Scell_log, stab);
424
425	return 0;
426}
427
428static const struct nla_policy gred_policy[TCA_GRED_MAX + 1] = {
429	[TCA_GRED_PARMS]	= { .len = sizeof(struct tc_gred_qopt) },
430	[TCA_GRED_STAB]		= { .len = 256 },
431	[TCA_GRED_DPS]		= { .len = sizeof(struct tc_gred_sopt) },
432};
433
434static int gred_change(struct Qdisc *sch, struct nlattr *opt)
435{
436	struct gred_sched *table = qdisc_priv(sch);
437	struct tc_gred_qopt *ctl;
438	struct nlattr *tb[TCA_GRED_MAX + 1];
439	int err, prio = GRED_DEF_PRIO;
440	u8 *stab;
441
442	if (opt == NULL)
443		return -EINVAL;
444
445	err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy);
446	if (err < 0)
447		return err;
448
449	if (tb[TCA_GRED_PARMS] == NULL && tb[TCA_GRED_STAB] == NULL)
450		return gred_change_table_def(sch, opt);
451
452	if (tb[TCA_GRED_PARMS] == NULL ||
453	    tb[TCA_GRED_STAB] == NULL)
454		return -EINVAL;
455
456	err = -EINVAL;
457	ctl = nla_data(tb[TCA_GRED_PARMS]);
458	stab = nla_data(tb[TCA_GRED_STAB]);
459
460	if (ctl->DP >= table->DPs)
461		goto errout;
462
463	if (gred_rio_mode(table)) {
464		if (ctl->prio == 0) {
465			int def_prio = GRED_DEF_PRIO;
466
467			if (table->tab[table->def])
468				def_prio = table->tab[table->def]->prio;
469
470			printk(KERN_DEBUG "GRED: DP %u does not have a prio "
471			       "setting default to %d\n", ctl->DP, def_prio);
472
473			prio = def_prio;
474		} else
475			prio = ctl->prio;
476	}
477
478	sch_tree_lock(sch);
479
480	err = gred_change_vq(sch, ctl->DP, ctl, prio, stab);
481	if (err < 0)
482		goto errout_locked;
483
484	if (gred_rio_mode(table)) {
485		gred_disable_wred_mode(table);
486		if (gred_wred_mode_check(sch))
487			gred_enable_wred_mode(table);
488	}
489
490	err = 0;
491
492errout_locked:
493	sch_tree_unlock(sch);
494errout:
495	return err;
496}
497
498static int gred_init(struct Qdisc *sch, struct nlattr *opt)
499{
500	struct nlattr *tb[TCA_GRED_MAX + 1];
501	int err;
502
503	if (opt == NULL)
504		return -EINVAL;
505
506	err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy);
507	if (err < 0)
508		return err;
509
510	if (tb[TCA_GRED_PARMS] || tb[TCA_GRED_STAB])
511		return -EINVAL;
512
513	return gred_change_table_def(sch, tb[TCA_GRED_DPS]);
514}
515
516static int gred_dump(struct Qdisc *sch, struct sk_buff *skb)
517{
518	struct gred_sched *table = qdisc_priv(sch);
519	struct nlattr *parms, *opts = NULL;
520	int i;
521	struct tc_gred_sopt sopt = {
522		.DPs	= table->DPs,
523		.def_DP	= table->def,
524		.grio	= gred_rio_mode(table),
525		.flags	= table->red_flags,
526	};
527
528	opts = nla_nest_start(skb, TCA_OPTIONS);
529	if (opts == NULL)
530		goto nla_put_failure;
531	NLA_PUT(skb, TCA_GRED_DPS, sizeof(sopt), &sopt);
532	parms = nla_nest_start(skb, TCA_GRED_PARMS);
533	if (parms == NULL)
534		goto nla_put_failure;
535
536	for (i = 0; i < MAX_DPs; i++) {
537		struct gred_sched_data *q = table->tab[i];
538		struct tc_gred_qopt opt;
539
540		memset(&opt, 0, sizeof(opt));
541
542		if (!q) {
543			/* hack -- fix at some point with proper message
544			   This is how we indicate to tc that there is no VQ
545			   at this DP */
546
547			opt.DP = MAX_DPs + i;
548			goto append_opt;
549		}
550
551		opt.limit	= q->limit;
552		opt.DP		= q->DP;
553		opt.backlog	= q->backlog;
554		opt.prio	= q->prio;
555		opt.qth_min	= q->parms.qth_min >> q->parms.Wlog;
556		opt.qth_max	= q->parms.qth_max >> q->parms.Wlog;
557		opt.Wlog	= q->parms.Wlog;
558		opt.Plog	= q->parms.Plog;
559		opt.Scell_log	= q->parms.Scell_log;
560		opt.other	= q->stats.other;
561		opt.early	= q->stats.prob_drop;
562		opt.forced	= q->stats.forced_drop;
563		opt.pdrop	= q->stats.pdrop;
564		opt.packets	= q->packetsin;
565		opt.bytesin	= q->bytesin;
566
567		if (gred_wred_mode(table)) {
568			q->parms.qidlestart =
569				table->tab[table->def]->parms.qidlestart;
570			q->parms.qavg = table->tab[table->def]->parms.qavg;
571		}
572
573		opt.qave = red_calc_qavg(&q->parms, q->parms.qavg);
574
575append_opt:
576		if (nla_append(skb, sizeof(opt), &opt) < 0)
577			goto nla_put_failure;
578	}
579
580	nla_nest_end(skb, parms);
581
582	return nla_nest_end(skb, opts);
583
584nla_put_failure:
585	nla_nest_cancel(skb, opts);
586	return -EMSGSIZE;
587}
588
589static void gred_destroy(struct Qdisc *sch)
590{
591	struct gred_sched *table = qdisc_priv(sch);
592	int i;
593
594	for (i = 0; i < table->DPs; i++) {
595		if (table->tab[i])
596			gred_destroy_vq(table->tab[i]);
597	}
598}
599
600static struct Qdisc_ops gred_qdisc_ops __read_mostly = {
601	.id		=	"gred",
602	.priv_size	=	sizeof(struct gred_sched),
603	.enqueue	=	gred_enqueue,
604	.dequeue	=	gred_dequeue,
605	.requeue	=	gred_requeue,
606	.drop		=	gred_drop,
607	.init		=	gred_init,
608	.reset		=	gred_reset,
609	.destroy	=	gred_destroy,
610	.change		=	gred_change,
611	.dump		=	gred_dump,
612	.owner		=	THIS_MODULE,
613};
614
615static int __init gred_module_init(void)
616{
617	return register_qdisc(&gred_qdisc_ops);
618}
619
620static void __exit gred_module_exit(void)
621{
622	unregister_qdisc(&gred_qdisc_ops);
623}
624
625module_init(gred_module_init)
626module_exit(gred_module_exit)
627
628MODULE_LICENSE("GPL");
629