sch_gred.c revision 5a0e3ad6af8660be21ca98a971cd00f331318c05 
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
32struct gred_sched_data;
33struct gred_sched;
34
35struct gred_sched_data
36{
37	u32		limit;		/* HARD maximal queue length	*/
38	u32      	DP;		/* the drop pramaters */
39	u32		bytesin;	/* bytes seen on virtualQ so far*/
40	u32		packetsin;	/* packets seen on virtualQ so far*/
41	u32		backlog;	/* bytes on the virtualQ */
42	u8		prio;		/* the prio of this vq */
43
44	struct red_parms parms;
45	struct red_stats stats;
46};
47
48enum {
49	GRED_WRED_MODE = 1,
50	GRED_RIO_MODE,
51};
52
53struct gred_sched
54{
55	struct gred_sched_data *tab[MAX_DPs];
56	unsigned long	flags;
57	u32		red_flags;
58	u32 		DPs;
59	u32 		def;
60	struct red_parms wred_set;
61};
62
63static inline int gred_wred_mode(struct gred_sched *table)
64{
65	return test_bit(GRED_WRED_MODE, &table->flags);
66}
67
68static inline void gred_enable_wred_mode(struct gred_sched *table)
69{
70	__set_bit(GRED_WRED_MODE, &table->flags);
71}
72
73static inline void gred_disable_wred_mode(struct gred_sched *table)
74{
75	__clear_bit(GRED_WRED_MODE, &table->flags);
76}
77
78static inline int gred_rio_mode(struct gred_sched *table)
79{
80	return test_bit(GRED_RIO_MODE, &table->flags);
81}
82
83static inline void gred_enable_rio_mode(struct gred_sched *table)
84{
85	__set_bit(GRED_RIO_MODE, &table->flags);
86}
87
88static inline void gred_disable_rio_mode(struct gred_sched *table)
89{
90	__clear_bit(GRED_RIO_MODE, &table->flags);
91}
92
93static inline int gred_wred_mode_check(struct Qdisc *sch)
94{
95	struct gred_sched *table = qdisc_priv(sch);
96	int i;
97
98	/* Really ugly O(n^2) but shouldn't be necessary too frequent. */
99	for (i = 0; i < table->DPs; i++) {
100		struct gred_sched_data *q = table->tab[i];
101		int n;
102
103		if (q == NULL)
104			continue;
105
106		for (n = 0; n < table->DPs; n++)
107			if (table->tab[n] && table->tab[n] != q &&
108			    table->tab[n]->prio == q->prio)
109				return 1;
110	}
111
112	return 0;
113}
114
115static inline unsigned int gred_backlog(struct gred_sched *table,
116					struct gred_sched_data *q,
117					struct Qdisc *sch)
118{
119	if (gred_wred_mode(table))
120		return sch->qstats.backlog;
121	else
122		return q->backlog;
123}
124
125static inline u16 tc_index_to_dp(struct sk_buff *skb)
126{
127	return skb->tc_index & GRED_VQ_MASK;
128}
129
130static inline void gred_load_wred_set(struct gred_sched *table,
131				      struct gred_sched_data *q)
132{
133	q->parms.qavg = table->wred_set.qavg;
134	q->parms.qidlestart = table->wred_set.qidlestart;
135}
136
137static inline void gred_store_wred_set(struct gred_sched *table,
138				       struct gred_sched_data *q)
139{
140	table->wred_set.qavg = q->parms.qavg;
141}
142
143static inline int gred_use_ecn(struct gred_sched *t)
144{
145	return t->red_flags & TC_RED_ECN;
146}
147
148static inline int gred_use_harddrop(struct gred_sched *t)
149{
150	return t->red_flags & TC_RED_HARDDROP;
151}
152
153static int gred_enqueue(struct sk_buff *skb, struct Qdisc* sch)
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		if ((q = t->tab[dp]) == NULL) {
164			/* Pass through packets not assigned to a DP
165			 * if no default DP has been configured. This
166			 * allows for DP flows to be left untouched.
167			 */
168			if (skb_queue_len(&sch->q) < qdisc_dev(sch)->tx_queue_len)
169				return qdisc_enqueue_tail(skb, sch);
170			else
171				goto drop;
172		}
173
174		/* fix tc_index? --could be controvesial but needed for
175		   requeueing */
176		skb->tc_index = (skb->tc_index & ~GRED_VQ_MASK) | dp;
177	}
178
179	/* sum up all the qaves of prios <= to ours to get the new qave */
180	if (!gred_wred_mode(t) && gred_rio_mode(t)) {
181		int i;
182
183		for (i = 0; i < t->DPs; i++) {
184			if (t->tab[i] && t->tab[i]->prio < q->prio &&
185			    !red_is_idling(&t->tab[i]->parms))
186				qavg +=t->tab[i]->parms.qavg;
187		}
188
189	}
190
191	q->packetsin++;
192	q->bytesin += qdisc_pkt_len(skb);
193
194	if (gred_wred_mode(t))
195		gred_load_wred_set(t, q);
196
197	q->parms.qavg = red_calc_qavg(&q->parms, gred_backlog(t, q, sch));
198
199	if (red_is_idling(&q->parms))
200		red_end_of_idle_period(&q->parms);
201
202	if (gred_wred_mode(t))
203		gred_store_wred_set(t, q);
204
205	switch (red_action(&q->parms, q->parms.qavg + qavg)) {
206		case RED_DONT_MARK:
207			break;
208
209		case RED_PROB_MARK:
210			sch->qstats.overlimits++;
211			if (!gred_use_ecn(t) || !INET_ECN_set_ce(skb)) {
212				q->stats.prob_drop++;
213				goto congestion_drop;
214			}
215
216			q->stats.prob_mark++;
217			break;
218
219		case RED_HARD_MARK:
220			sch->qstats.overlimits++;
221			if (gred_use_harddrop(t) || !gred_use_ecn(t) ||
222			    !INET_ECN_set_ce(skb)) {
223				q->stats.forced_drop++;
224				goto congestion_drop;
225			}
226			q->stats.forced_mark++;
227			break;
228	}
229
230	if (q->backlog + qdisc_pkt_len(skb) <= q->limit) {
231		q->backlog += qdisc_pkt_len(skb);
232		return qdisc_enqueue_tail(skb, sch);
233	}
234
235	q->stats.pdrop++;
236drop:
237	return qdisc_drop(skb, sch);
238
239congestion_drop:
240	qdisc_drop(skb, sch);
241	return NET_XMIT_CN;
242}
243
244static struct sk_buff *gred_dequeue(struct Qdisc* sch)
245{
246	struct sk_buff *skb;
247	struct gred_sched *t = qdisc_priv(sch);
248
249	skb = qdisc_dequeue_head(sch);
250
251	if (skb) {
252		struct gred_sched_data *q;
253		u16 dp = tc_index_to_dp(skb);
254
255		if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
256			if (net_ratelimit())
257				printk(KERN_WARNING "GRED: Unable to relocate "
258				       "VQ 0x%x after dequeue, screwing up "
259				       "backlog.\n", tc_index_to_dp(skb));
260		} else {
261			q->backlog -= qdisc_pkt_len(skb);
262
263			if (!q->backlog && !gred_wred_mode(t))
264				red_start_of_idle_period(&q->parms);
265		}
266
267		return skb;
268	}
269
270	if (gred_wred_mode(t) && !red_is_idling(&t->wred_set))
271		red_start_of_idle_period(&t->wred_set);
272
273	return NULL;
274}
275
276static unsigned int gred_drop(struct Qdisc* sch)
277{
278	struct sk_buff *skb;
279	struct gred_sched *t = qdisc_priv(sch);
280
281	skb = qdisc_dequeue_tail(sch);
282	if (skb) {
283		unsigned int len = qdisc_pkt_len(skb);
284		struct gred_sched_data *q;
285		u16 dp = tc_index_to_dp(skb);
286
287		if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
288			if (net_ratelimit())
289				printk(KERN_WARNING "GRED: Unable to relocate "
290				       "VQ 0x%x while dropping, screwing up "
291				       "backlog.\n", tc_index_to_dp(skb));
292		} else {
293			q->backlog -= len;
294			q->stats.other++;
295
296			if (!q->backlog && !gred_wred_mode(t))
297				red_start_of_idle_period(&q->parms);
298		}
299
300		qdisc_drop(skb, sch);
301		return len;
302	}
303
304	if (gred_wred_mode(t) && !red_is_idling(&t->wred_set))
305		red_start_of_idle_period(&t->wred_set);
306
307	return 0;
308
309}
310
311static void gred_reset(struct Qdisc* sch)
312{
313	int i;
314	struct gred_sched *t = qdisc_priv(sch);
315
316	qdisc_reset_queue(sch);
317
318	for (i = 0; i < t->DPs; i++) {
319		struct gred_sched_data *q = t->tab[i];
320
321		if (!q)
322			continue;
323
324		red_restart(&q->parms);
325		q->backlog = 0;
326	}
327}
328
329static inline void gred_destroy_vq(struct gred_sched_data *q)
330{
331	kfree(q);
332}
333
334static inline int gred_change_table_def(struct Qdisc *sch, struct nlattr *dps)
335{
336	struct gred_sched *table = qdisc_priv(sch);
337	struct tc_gred_sopt *sopt;
338	int i;
339
340	if (dps == NULL)
341		return -EINVAL;
342
343	sopt = nla_data(dps);
344
345	if (sopt->DPs > MAX_DPs || sopt->DPs == 0 || sopt->def_DP >= sopt->DPs)
346		return -EINVAL;
347
348	sch_tree_lock(sch);
349	table->DPs = sopt->DPs;
350	table->def = sopt->def_DP;
351	table->red_flags = sopt->flags;
352
353	/*
354	 * Every entry point to GRED is synchronized with the above code
355	 * and the DP is checked against DPs, i.e. shadowed VQs can no
356	 * longer be found so we can unlock right here.
357	 */
358	sch_tree_unlock(sch);
359
360	if (sopt->grio) {
361		gred_enable_rio_mode(table);
362		gred_disable_wred_mode(table);
363		if (gred_wred_mode_check(sch))
364			gred_enable_wred_mode(table);
365	} else {
366		gred_disable_rio_mode(table);
367		gred_disable_wred_mode(table);
368	}
369
370	for (i = table->DPs; i < MAX_DPs; i++) {
371		if (table->tab[i]) {
372			printk(KERN_WARNING "GRED: Warning: Destroying "
373			       "shadowed VQ 0x%x\n", i);
374			gred_destroy_vq(table->tab[i]);
375			table->tab[i] = NULL;
376		}
377	}
378
379	return 0;
380}
381
382static inline int gred_change_vq(struct Qdisc *sch, int dp,
383				 struct tc_gred_qopt *ctl, int prio, u8 *stab)
384{
385	struct gred_sched *table = qdisc_priv(sch);
386	struct gred_sched_data *q;
387
388	if (table->tab[dp] == NULL) {
389		table->tab[dp] = kzalloc(sizeof(*q), GFP_KERNEL);
390		if (table->tab[dp] == NULL)
391			return -ENOMEM;
392	}
393
394	q = table->tab[dp];
395	q->DP = dp;
396	q->prio = prio;
397	q->limit = ctl->limit;
398
399	if (q->backlog == 0)
400		red_end_of_idle_period(&q->parms);
401
402	red_set_parms(&q->parms,
403		      ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Plog,
404		      ctl->Scell_log, stab);
405
406	return 0;
407}
408
409static const struct nla_policy gred_policy[TCA_GRED_MAX + 1] = {
410	[TCA_GRED_PARMS]	= { .len = sizeof(struct tc_gred_qopt) },
411	[TCA_GRED_STAB]		= { .len = 256 },
412	[TCA_GRED_DPS]		= { .len = sizeof(struct tc_gred_sopt) },
413};
414
415static int gred_change(struct Qdisc *sch, struct nlattr *opt)
416{
417	struct gred_sched *table = qdisc_priv(sch);
418	struct tc_gred_qopt *ctl;
419	struct nlattr *tb[TCA_GRED_MAX + 1];
420	int err, prio = GRED_DEF_PRIO;
421	u8 *stab;
422
423	if (opt == NULL)
424		return -EINVAL;
425
426	err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy);
427	if (err < 0)
428		return err;
429
430	if (tb[TCA_GRED_PARMS] == NULL && tb[TCA_GRED_STAB] == NULL)
431		return gred_change_table_def(sch, opt);
432
433	if (tb[TCA_GRED_PARMS] == NULL ||
434	    tb[TCA_GRED_STAB] == NULL)
435		return -EINVAL;
436
437	err = -EINVAL;
438	ctl = nla_data(tb[TCA_GRED_PARMS]);
439	stab = nla_data(tb[TCA_GRED_STAB]);
440
441	if (ctl->DP >= table->DPs)
442		goto errout;
443
444	if (gred_rio_mode(table)) {
445		if (ctl->prio == 0) {
446			int def_prio = GRED_DEF_PRIO;
447
448			if (table->tab[table->def])
449				def_prio = table->tab[table->def]->prio;
450
451			printk(KERN_DEBUG "GRED: DP %u does not have a prio "
452			       "setting default to %d\n", ctl->DP, def_prio);
453
454			prio = def_prio;
455		} else
456			prio = ctl->prio;
457	}
458
459	sch_tree_lock(sch);
460
461	err = gred_change_vq(sch, ctl->DP, ctl, prio, stab);
462	if (err < 0)
463		goto errout_locked;
464
465	if (gred_rio_mode(table)) {
466		gred_disable_wred_mode(table);
467		if (gred_wred_mode_check(sch))
468			gred_enable_wred_mode(table);
469	}
470
471	err = 0;
472
473errout_locked:
474	sch_tree_unlock(sch);
475errout:
476	return err;
477}
478
479static int gred_init(struct Qdisc *sch, struct nlattr *opt)
480{
481	struct nlattr *tb[TCA_GRED_MAX + 1];
482	int err;
483
484	if (opt == NULL)
485		return -EINVAL;
486
487	err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy);
488	if (err < 0)
489		return err;
490
491	if (tb[TCA_GRED_PARMS] || tb[TCA_GRED_STAB])
492		return -EINVAL;
493
494	return gred_change_table_def(sch, tb[TCA_GRED_DPS]);
495}
496
497static int gred_dump(struct Qdisc *sch, struct sk_buff *skb)
498{
499	struct gred_sched *table = qdisc_priv(sch);
500	struct nlattr *parms, *opts = NULL;
501	int i;
502	struct tc_gred_sopt sopt = {
503		.DPs	= table->DPs,
504		.def_DP	= table->def,
505		.grio	= gred_rio_mode(table),
506		.flags	= table->red_flags,
507	};
508
509	opts = nla_nest_start(skb, TCA_OPTIONS);
510	if (opts == NULL)
511		goto nla_put_failure;
512	NLA_PUT(skb, TCA_GRED_DPS, sizeof(sopt), &sopt);
513	parms = nla_nest_start(skb, TCA_GRED_PARMS);
514	if (parms == NULL)
515		goto nla_put_failure;
516
517	for (i = 0; i < MAX_DPs; i++) {
518		struct gred_sched_data *q = table->tab[i];
519		struct tc_gred_qopt opt;
520
521		memset(&opt, 0, sizeof(opt));
522
523		if (!q) {
524			/* hack -- fix at some point with proper message
525			   This is how we indicate to tc that there is no VQ
526			   at this DP */
527
528			opt.DP = MAX_DPs + i;
529			goto append_opt;
530		}
531
532		opt.limit	= q->limit;
533		opt.DP		= q->DP;
534		opt.backlog	= q->backlog;
535		opt.prio	= q->prio;
536		opt.qth_min	= q->parms.qth_min >> q->parms.Wlog;
537		opt.qth_max	= q->parms.qth_max >> q->parms.Wlog;
538		opt.Wlog	= q->parms.Wlog;
539		opt.Plog	= q->parms.Plog;
540		opt.Scell_log	= q->parms.Scell_log;
541		opt.other	= q->stats.other;
542		opt.early	= q->stats.prob_drop;
543		opt.forced	= q->stats.forced_drop;
544		opt.pdrop	= q->stats.pdrop;
545		opt.packets	= q->packetsin;
546		opt.bytesin	= q->bytesin;
547
548		if (gred_wred_mode(table)) {
549			q->parms.qidlestart =
550				table->tab[table->def]->parms.qidlestart;
551			q->parms.qavg = table->tab[table->def]->parms.qavg;
552		}
553
554		opt.qave = red_calc_qavg(&q->parms, q->parms.qavg);
555
556append_opt:
557		if (nla_append(skb, sizeof(opt), &opt) < 0)
558			goto nla_put_failure;
559	}
560
561	nla_nest_end(skb, parms);
562
563	return nla_nest_end(skb, opts);
564
565nla_put_failure:
566	nla_nest_cancel(skb, opts);
567	return -EMSGSIZE;
568}
569
570static void gred_destroy(struct Qdisc *sch)
571{
572	struct gred_sched *table = qdisc_priv(sch);
573	int i;
574
575	for (i = 0; i < table->DPs; i++) {
576		if (table->tab[i])
577			gred_destroy_vq(table->tab[i]);
578	}
579}
580
581static struct Qdisc_ops gred_qdisc_ops __read_mostly = {
582	.id		=	"gred",
583	.priv_size	=	sizeof(struct gred_sched),
584	.enqueue	=	gred_enqueue,
585	.dequeue	=	gred_dequeue,
586	.peek		=	qdisc_peek_head,
587	.drop		=	gred_drop,
588	.init		=	gred_init,
589	.reset		=	gred_reset,
590	.destroy	=	gred_destroy,
591	.change		=	gred_change,
592	.dump		=	gred_dump,
593	.owner		=	THIS_MODULE,
594};
595
596static int __init gred_module_init(void)
597{
598	return register_qdisc(&gred_qdisc_ops);
599}
600
601static void __exit gred_module_exit(void)
602{
603	unregister_qdisc(&gred_qdisc_ops);
604}
605
606module_init(gred_module_init)
607module_exit(gred_module_exit)
608
609MODULE_LICENSE("GPL");
610