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Linux/net/sched/sch_gred.c

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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)
310                 return -EINVAL;
311 
312         sopt = nla_data(dps);
313 
314         if (sopt->DPs > MAX_DPs || sopt->DPs == 0 ||
315             sopt->def_DP >= sopt->DPs)
316                 return -EINVAL;
317 
318         sch_tree_lock(sch);
319         table->DPs = sopt->DPs;
320         table->def = sopt->def_DP;
321         table->red_flags = sopt->flags;
322 
323         /*
324          * Every entry point to GRED is synchronized with the above code
325          * and the DP is checked against DPs, i.e. shadowed VQs can no
326          * longer be found so we can unlock right here.
327          */
328         sch_tree_unlock(sch);
329 
330         if (sopt->grio) {
331                 gred_enable_rio_mode(table);
332                 gred_disable_wred_mode(table);
333                 if (gred_wred_mode_check(sch))
334                         gred_enable_wred_mode(table);
335         } else {
336                 gred_disable_rio_mode(table);
337                 gred_disable_wred_mode(table);
338         }
339 
340         for (i = table->DPs; i < MAX_DPs; i++) {
341                 if (table->tab[i]) {
342                         pr_warn("GRED: Warning: Destroying shadowed VQ 0x%x\n",
343                                 i);
344                         gred_destroy_vq(table->tab[i]);
345                         table->tab[i] = NULL;
346                 }
347         }
348 
349         return 0;
350 }
351 
352 static inline int gred_change_vq(struct Qdisc *sch, int dp,
353                                  struct tc_gred_qopt *ctl, int prio,
354                                  u8 *stab, u32 max_P,
355                                  struct gred_sched_data **prealloc)
356 {
357         struct gred_sched *table = qdisc_priv(sch);
358         struct gred_sched_data *q = table->tab[dp];
359 
360         if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog))
361                 return -EINVAL;
362 
363         if (!q) {
364                 table->tab[dp] = q = *prealloc;
365                 *prealloc = NULL;
366                 if (!q)
367                         return -ENOMEM;
368         }
369 
370         q->DP = dp;
371         q->prio = prio;
372         if (ctl->limit > sch->limit)
373                 q->limit = sch->limit;
374         else
375                 q->limit = ctl->limit;
376 
377         if (q->backlog == 0)
378                 red_end_of_idle_period(&q->vars);
379 
380         red_set_parms(&q->parms,
381                       ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Plog,
382                       ctl->Scell_log, stab, max_P);
383         red_set_vars(&q->vars);
384         return 0;
385 }
386 
387 static const struct nla_policy gred_policy[TCA_GRED_MAX + 1] = {
388         [TCA_GRED_PARMS]        = { .len = sizeof(struct tc_gred_qopt) },
389         [TCA_GRED_STAB]         = { .len = 256 },
390         [TCA_GRED_DPS]          = { .len = sizeof(struct tc_gred_sopt) },
391         [TCA_GRED_MAX_P]        = { .type = NLA_U32 },
392         [TCA_GRED_LIMIT]        = { .type = NLA_U32 },
393 };
394 
395 static int gred_change(struct Qdisc *sch, struct nlattr *opt,
396                        struct netlink_ext_ack *extack)
397 {
398         struct gred_sched *table = qdisc_priv(sch);
399         struct tc_gred_qopt *ctl;
400         struct nlattr *tb[TCA_GRED_MAX + 1];
401         int err, prio = GRED_DEF_PRIO;
402         u8 *stab;
403         u32 max_P;
404         struct gred_sched_data *prealloc;
405 
406         if (opt == NULL)
407                 return -EINVAL;
408 
409         err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy, NULL);
410         if (err < 0)
411                 return err;
412 
413         if (tb[TCA_GRED_PARMS] == NULL && tb[TCA_GRED_STAB] == NULL) {
414                 if (tb[TCA_GRED_LIMIT] != NULL)
415                         sch->limit = nla_get_u32(tb[TCA_GRED_LIMIT]);
416                 return gred_change_table_def(sch, tb[TCA_GRED_DPS]);
417         }
418 
419         if (tb[TCA_GRED_PARMS] == NULL ||
420             tb[TCA_GRED_STAB] == NULL ||
421             tb[TCA_GRED_LIMIT] != NULL)
422                 return -EINVAL;
423 
424         max_P = tb[TCA_GRED_MAX_P] ? nla_get_u32(tb[TCA_GRED_MAX_P]) : 0;
425 
426         err = -EINVAL;
427         ctl = nla_data(tb[TCA_GRED_PARMS]);
428         stab = nla_data(tb[TCA_GRED_STAB]);
429 
430         if (ctl->DP >= table->DPs)
431                 goto errout;
432 
433         if (gred_rio_mode(table)) {
434                 if (ctl->prio == 0) {
435                         int def_prio = GRED_DEF_PRIO;
436 
437                         if (table->tab[table->def])
438                                 def_prio = table->tab[table->def]->prio;
439 
440                         printk(KERN_DEBUG "GRED: DP %u does not have a prio "
441                                "setting default to %d\n", ctl->DP, def_prio);
442 
443                         prio = def_prio;
444                 } else
445                         prio = ctl->prio;
446         }
447 
448         prealloc = kzalloc(sizeof(*prealloc), GFP_KERNEL);
449         sch_tree_lock(sch);
450 
451         err = gred_change_vq(sch, ctl->DP, ctl, prio, stab, max_P, &prealloc);
452         if (err < 0)
453                 goto errout_locked;
454 
455         if (gred_rio_mode(table)) {
456                 gred_disable_wred_mode(table);
457                 if (gred_wred_mode_check(sch))
458                         gred_enable_wred_mode(table);
459         }
460 
461         err = 0;
462 
463 errout_locked:
464         sch_tree_unlock(sch);
465         kfree(prealloc);
466 errout:
467         return err;
468 }
469 
470 static int gred_init(struct Qdisc *sch, struct nlattr *opt,
471                      struct netlink_ext_ack *extack)
472 {
473         struct nlattr *tb[TCA_GRED_MAX + 1];
474         int err;
475 
476         if (!opt)
477                 return -EINVAL;
478 
479         err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy, NULL);
480         if (err < 0)
481                 return err;
482 
483         if (tb[TCA_GRED_PARMS] || tb[TCA_GRED_STAB])
484                 return -EINVAL;
485 
486         if (tb[TCA_GRED_LIMIT])
487                 sch->limit = nla_get_u32(tb[TCA_GRED_LIMIT]);
488         else
489                 sch->limit = qdisc_dev(sch)->tx_queue_len
490                              * psched_mtu(qdisc_dev(sch));
491 
492         return gred_change_table_def(sch, tb[TCA_GRED_DPS]);
493 }
494 
495 static int gred_dump(struct Qdisc *sch, struct sk_buff *skb)
496 {
497         struct gred_sched *table = qdisc_priv(sch);
498         struct nlattr *parms, *opts = NULL;
499         int i;
500         u32 max_p[MAX_DPs];
501         struct tc_gred_sopt sopt = {
502                 .DPs    = table->DPs,
503                 .def_DP = table->def,
504                 .grio   = gred_rio_mode(table),
505                 .flags  = table->red_flags,
506         };
507 
508         opts = nla_nest_start(skb, TCA_OPTIONS);
509         if (opts == NULL)
510                 goto nla_put_failure;
511         if (nla_put(skb, TCA_GRED_DPS, sizeof(sopt), &sopt))
512                 goto nla_put_failure;
513 
514         for (i = 0; i < MAX_DPs; i++) {
515                 struct gred_sched_data *q = table->tab[i];
516 
517                 max_p[i] = q ? q->parms.max_P : 0;
518         }
519         if (nla_put(skb, TCA_GRED_MAX_P, sizeof(max_p), max_p))
520                 goto nla_put_failure;
521 
522         if (nla_put_u32(skb, TCA_GRED_LIMIT, sch->limit))
523                 goto nla_put_failure;
524 
525         parms = nla_nest_start(skb, TCA_GRED_PARMS);
526         if (parms == NULL)
527                 goto nla_put_failure;
528 
529         for (i = 0; i < MAX_DPs; i++) {
530                 struct gred_sched_data *q = table->tab[i];
531                 struct tc_gred_qopt opt;
532                 unsigned long qavg;
533 
534                 memset(&opt, 0, sizeof(opt));
535 
536                 if (!q) {
537                         /* hack -- fix at some point with proper message
538                            This is how we indicate to tc that there is no VQ
539                            at this DP */
540 
541                         opt.DP = MAX_DPs + i;
542                         goto append_opt;
543                 }
544 
545                 opt.limit       = q->limit;
546                 opt.DP          = q->DP;
547                 opt.backlog     = gred_backlog(table, q, sch);
548                 opt.prio        = q->prio;
549                 opt.qth_min     = q->parms.qth_min >> q->parms.Wlog;
550                 opt.qth_max     = q->parms.qth_max >> q->parms.Wlog;
551                 opt.Wlog        = q->parms.Wlog;
552                 opt.Plog        = q->parms.Plog;
553                 opt.Scell_log   = q->parms.Scell_log;
554                 opt.other       = q->stats.other;
555                 opt.early       = q->stats.prob_drop;
556                 opt.forced      = q->stats.forced_drop;
557                 opt.pdrop       = q->stats.pdrop;
558                 opt.packets     = q->packetsin;
559                 opt.bytesin     = q->bytesin;
560 
561                 if (gred_wred_mode(table))
562                         gred_load_wred_set(table, q);
563 
564                 qavg = red_calc_qavg(&q->parms, &q->vars,
565                                      q->vars.qavg >> q->parms.Wlog);
566                 opt.qave = qavg >> q->parms.Wlog;
567 
568 append_opt:
569                 if (nla_append(skb, sizeof(opt), &opt) < 0)
570                         goto nla_put_failure;
571         }
572 
573         nla_nest_end(skb, parms);
574 
575         return nla_nest_end(skb, opts);
576 
577 nla_put_failure:
578         nla_nest_cancel(skb, opts);
579         return -EMSGSIZE;
580 }
581 
582 static void gred_destroy(struct Qdisc *sch)
583 {
584         struct gred_sched *table = qdisc_priv(sch);
585         int i;
586 
587         for (i = 0; i < table->DPs; i++) {
588                 if (table->tab[i])
589                         gred_destroy_vq(table->tab[i]);
590         }
591 }
592 
593 static struct Qdisc_ops gred_qdisc_ops __read_mostly = {
594         .id             =       "gred",
595         .priv_size      =       sizeof(struct gred_sched),
596         .enqueue        =       gred_enqueue,
597         .dequeue        =       gred_dequeue,
598         .peek           =       qdisc_peek_head,
599         .init           =       gred_init,
600         .reset          =       gred_reset,
601         .destroy        =       gred_destroy,
602         .change         =       gred_change,
603         .dump           =       gred_dump,
604         .owner          =       THIS_MODULE,
605 };
606 
607 static int __init gred_module_init(void)
608 {
609         return register_qdisc(&gred_qdisc_ops);
610 }
611 
612 static void __exit gred_module_exit(void)
613 {
614         unregister_qdisc(&gred_qdisc_ops);
615 }
616 
617 module_init(gred_module_init)
618 module_exit(gred_module_exit)
619 
620 MODULE_LICENSE("GPL");
621 

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