cb20ee3b9fc255dc86bf4d4a16d9a6b25a4b4b96
[linux-2.6.git] / net / sched / sch_gred.c
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
31 struct gred_sched_data;
32 struct gred_sched;
33
34 struct 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
47 enum {
48         GRED_WRED_MODE = 1,
49         GRED_RIO_MODE,
50 };
51
52 struct 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
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 = 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
114 static 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
124 static inline u16 tc_index_to_dp(struct sk_buff *skb)
125 {
126         return skb->tc_index & GRED_VQ_MASK;
127 }
128
129 static 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
136 static 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
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 {
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 += qdisc_pkt_len(skb);
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 + qdisc_pkt_len(skb) <= q->limit) {
230                 q->backlog += qdisc_pkt_len(skb);
231                 return qdisc_enqueue_tail(skb, sch);
232         }
233
234         q->stats.pdrop++;
235 drop:
236         return qdisc_drop(skb, sch);
237
238 congestion_drop:
239         qdisc_drop(skb, sch);
240         return NET_XMIT_CN;
241 }
242
243 static 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 += qdisc_pkt_len(skb);
258         }
259
260         return qdisc_requeue(skb, sch);
261 }
262
263 static 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 -= qdisc_pkt_len(skb);
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
295 static 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 = qdisc_pkt_len(skb);
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
330 static 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
348 static inline void gred_destroy_vq(struct gred_sched_data *q)
349 {
350         kfree(q);
351 }
352
353 static 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
401 static 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
428 static 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
434 static 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
492 errout_locked:
493         sch_tree_unlock(sch);
494 errout:
495         return err;
496 }
497
498 static 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
516 static 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
575 append_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
584 nla_put_failure:
585         nla_nest_cancel(skb, opts);
586         return -EMSGSIZE;
587 }
588
589 static 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
600 static 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         .peek           =       qdisc_peek_head,
606         .requeue        =       gred_requeue,
607         .drop           =       gred_drop,
608         .init           =       gred_init,
609         .reset          =       gred_reset,
610         .destroy        =       gred_destroy,
611         .change         =       gred_change,
612         .dump           =       gred_dump,
613         .owner          =       THIS_MODULE,
614 };
615
616 static int __init gred_module_init(void)
617 {
618         return register_qdisc(&gred_qdisc_ops);
619 }
620
621 static void __exit gred_module_exit(void)
622 {
623         unregister_qdisc(&gred_qdisc_ops);
624 }
625
626 module_init(gred_module_init)
627 module_exit(gred_module_exit)
628
629 MODULE_LICENSE("GPL");