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Linux/net/sched/sch_htb.c

  1 /*
  2  * net/sched/sch_htb.c  Hierarchical token bucket, feed tree version
  3  *
  4  *              This program is free software; you can redistribute it and/or
  5  *              modify it under the terms of the GNU General Public License
  6  *              as published by the Free Software Foundation; either version
  7  *              2 of the License, or (at your option) any later version.
  8  *
  9  * Authors:     Martin Devera, <devik@cdi.cz>
 10  *
 11  * Credits (in time order) for older HTB versions:
 12  *              Stef Coene <stef.coene@docum.org>
 13  *                      HTB support at LARTC mailing list
 14  *              Ondrej Kraus, <krauso@barr.cz>
 15  *                      found missing INIT_QDISC(htb)
 16  *              Vladimir Smelhaus, Aamer Akhter, Bert Hubert
 17  *                      helped a lot to locate nasty class stall bug
 18  *              Andi Kleen, Jamal Hadi, Bert Hubert
 19  *                      code review and helpful comments on shaping
 20  *              Tomasz Wrona, <tw@eter.tym.pl>
 21  *                      created test case so that I was able to fix nasty bug
 22  *              Wilfried Weissmann
 23  *                      spotted bug in dequeue code and helped with fix
 24  *              Jiri Fojtasek
 25  *                      fixed requeue routine
 26  *              and many others. thanks.
 27  */
 28 #include <linux/module.h>
 29 #include <linux/moduleparam.h>
 30 #include <linux/types.h>
 31 #include <linux/kernel.h>
 32 #include <linux/string.h>
 33 #include <linux/errno.h>
 34 #include <linux/skbuff.h>
 35 #include <linux/list.h>
 36 #include <linux/compiler.h>
 37 #include <linux/rbtree.h>
 38 #include <linux/workqueue.h>
 39 #include <linux/slab.h>
 40 #include <net/netlink.h>
 41 #include <net/sch_generic.h>
 42 #include <net/pkt_sched.h>
 43 
 44 /* HTB algorithm.
 45     Author: devik@cdi.cz
 46     ========================================================================
 47     HTB is like TBF with multiple classes. It is also similar to CBQ because
 48     it allows to assign priority to each class in hierarchy.
 49     In fact it is another implementation of Floyd's formal sharing.
 50 
 51     Levels:
 52     Each class is assigned level. Leaf has ALWAYS level 0 and root
 53     classes have level TC_HTB_MAXDEPTH-1. Interior nodes has level
 54     one less than their parent.
 55 */
 56 
 57 static int htb_hysteresis __read_mostly = 0; /* whether to use mode hysteresis for speedup */
 58 #define HTB_VER 0x30011         /* major must be matched with number suplied by TC as version */
 59 
 60 #if HTB_VER >> 16 != TC_HTB_PROTOVER
 61 #error "Mismatched sch_htb.c and pkt_sch.h"
 62 #endif
 63 
 64 /* Module parameter and sysfs export */
 65 module_param    (htb_hysteresis, int, 0640);
 66 MODULE_PARM_DESC(htb_hysteresis, "Hysteresis mode, less CPU load, less accurate");
 67 
 68 static int htb_rate_est = 0; /* htb classes have a default rate estimator */
 69 module_param(htb_rate_est, int, 0640);
 70 MODULE_PARM_DESC(htb_rate_est, "setup a default rate estimator (4sec 16sec) for htb classes");
 71 
 72 /* used internaly to keep status of single class */
 73 enum htb_cmode {
 74         HTB_CANT_SEND,          /* class can't send and can't borrow */
 75         HTB_MAY_BORROW,         /* class can't send but may borrow */
 76         HTB_CAN_SEND            /* class can send */
 77 };
 78 
 79 struct htb_prio {
 80         union {
 81                 struct rb_root  row;
 82                 struct rb_root  feed;
 83         };
 84         struct rb_node  *ptr;
 85         /* When class changes from state 1->2 and disconnects from
 86          * parent's feed then we lost ptr value and start from the
 87          * first child again. Here we store classid of the
 88          * last valid ptr (used when ptr is NULL).
 89          */
 90         u32             last_ptr_id;
 91 };
 92 
 93 /* interior & leaf nodes; props specific to leaves are marked L:
 94  * To reduce false sharing, place mostly read fields at beginning,
 95  * and mostly written ones at the end.
 96  */
 97 struct htb_class {
 98         struct Qdisc_class_common common;
 99         struct psched_ratecfg   rate;
100         struct psched_ratecfg   ceil;
101         s64                     buffer, cbuffer;/* token bucket depth/rate */
102         s64                     mbuffer;        /* max wait time */
103         u32                     prio;           /* these two are used only by leaves... */
104         int                     quantum;        /* but stored for parent-to-leaf return */
105 
106         struct tcf_proto __rcu  *filter_list;   /* class attached filters */
107         int                     filter_cnt;
108         int                     refcnt;         /* usage count of this class */
109 
110         int                     level;          /* our level (see above) */
111         unsigned int            children;
112         struct htb_class        *parent;        /* parent class */
113 
114         struct gnet_stats_rate_est64 rate_est;
115 
116         /*
117          * Written often fields
118          */
119         struct gnet_stats_basic_packed bstats;
120         struct gnet_stats_queue qstats;
121         struct tc_htb_xstats    xstats; /* our special stats */
122 
123         /* token bucket parameters */
124         s64                     tokens, ctokens;/* current number of tokens */
125         s64                     t_c;            /* checkpoint time */
126 
127         union {
128                 struct htb_class_leaf {
129                         struct list_head drop_list;
130                         int             deficit[TC_HTB_MAXDEPTH];
131                         struct Qdisc    *q;
132                 } leaf;
133                 struct htb_class_inner {
134                         struct htb_prio clprio[TC_HTB_NUMPRIO];
135                 } inner;
136         } un;
137         s64                     pq_key;
138 
139         int                     prio_activity;  /* for which prios are we active */
140         enum htb_cmode          cmode;          /* current mode of the class */
141         struct rb_node          pq_node;        /* node for event queue */
142         struct rb_node          node[TC_HTB_NUMPRIO];   /* node for self or feed tree */
143 };
144 
145 struct htb_level {
146         struct rb_root  wait_pq;
147         struct htb_prio hprio[TC_HTB_NUMPRIO];
148 };
149 
150 struct htb_sched {
151         struct Qdisc_class_hash clhash;
152         int                     defcls;         /* class where unclassified flows go to */
153         int                     rate2quantum;   /* quant = rate / rate2quantum */
154 
155         /* filters for qdisc itself */
156         struct tcf_proto __rcu  *filter_list;
157 
158 #define HTB_WARN_TOOMANYEVENTS  0x1
159         unsigned int            warned; /* only one warning */
160         int                     direct_qlen;
161         struct work_struct      work;
162 
163         /* non shaped skbs; let them go directly thru */
164         struct sk_buff_head     direct_queue;
165         long                    direct_pkts;
166 
167         struct qdisc_watchdog   watchdog;
168 
169         s64                     now;    /* cached dequeue time */
170         struct list_head        drops[TC_HTB_NUMPRIO];/* active leaves (for drops) */
171 
172         /* time of nearest event per level (row) */
173         s64                     near_ev_cache[TC_HTB_MAXDEPTH];
174 
175         int                     row_mask[TC_HTB_MAXDEPTH];
176 
177         struct htb_level        hlevel[TC_HTB_MAXDEPTH];
178 };
179 
180 /* find class in global hash table using given handle */
181 static inline struct htb_class *htb_find(u32 handle, struct Qdisc *sch)
182 {
183         struct htb_sched *q = qdisc_priv(sch);
184         struct Qdisc_class_common *clc;
185 
186         clc = qdisc_class_find(&q->clhash, handle);
187         if (clc == NULL)
188                 return NULL;
189         return container_of(clc, struct htb_class, common);
190 }
191 
192 /**
193  * htb_classify - classify a packet into class
194  *
195  * It returns NULL if the packet should be dropped or -1 if the packet
196  * should be passed directly thru. In all other cases leaf class is returned.
197  * We allow direct class selection by classid in priority. The we examine
198  * filters in qdisc and in inner nodes (if higher filter points to the inner
199  * node). If we end up with classid MAJOR:0 we enqueue the skb into special
200  * internal fifo (direct). These packets then go directly thru. If we still
201  * have no valid leaf we try to use MAJOR:default leaf. It still unsuccessful
202  * then finish and return direct queue.
203  */
204 #define HTB_DIRECT ((struct htb_class *)-1L)
205 
206 static struct htb_class *htb_classify(struct sk_buff *skb, struct Qdisc *sch,
207                                       int *qerr)
208 {
209         struct htb_sched *q = qdisc_priv(sch);
210         struct htb_class *cl;
211         struct tcf_result res;
212         struct tcf_proto *tcf;
213         int result;
214 
215         /* allow to select class by setting skb->priority to valid classid;
216          * note that nfmark can be used too by attaching filter fw with no
217          * rules in it
218          */
219         if (skb->priority == sch->handle)
220                 return HTB_DIRECT;      /* X:0 (direct flow) selected */
221         cl = htb_find(skb->priority, sch);
222         if (cl) {
223                 if (cl->level == 0)
224                         return cl;
225                 /* Start with inner filter chain if a non-leaf class is selected */
226                 tcf = rcu_dereference_bh(cl->filter_list);
227         } else {
228                 tcf = rcu_dereference_bh(q->filter_list);
229         }
230 
231         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
232         while (tcf && (result = tc_classify(skb, tcf, &res, false)) >= 0) {
233 #ifdef CONFIG_NET_CLS_ACT
234                 switch (result) {
235                 case TC_ACT_QUEUED:
236                 case TC_ACT_STOLEN:
237                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
238                 case TC_ACT_SHOT:
239                         return NULL;
240                 }
241 #endif
242                 cl = (void *)res.class;
243                 if (!cl) {
244                         if (res.classid == sch->handle)
245                                 return HTB_DIRECT;      /* X:0 (direct flow) */
246                         cl = htb_find(res.classid, sch);
247                         if (!cl)
248                                 break;  /* filter selected invalid classid */
249                 }
250                 if (!cl->level)
251                         return cl;      /* we hit leaf; return it */
252 
253                 /* we have got inner class; apply inner filter chain */
254                 tcf = rcu_dereference_bh(cl->filter_list);
255         }
256         /* classification failed; try to use default class */
257         cl = htb_find(TC_H_MAKE(TC_H_MAJ(sch->handle), q->defcls), sch);
258         if (!cl || cl->level)
259                 return HTB_DIRECT;      /* bad default .. this is safe bet */
260         return cl;
261 }
262 
263 /**
264  * htb_add_to_id_tree - adds class to the round robin list
265  *
266  * Routine adds class to the list (actually tree) sorted by classid.
267  * Make sure that class is not already on such list for given prio.
268  */
269 static void htb_add_to_id_tree(struct rb_root *root,
270                                struct htb_class *cl, int prio)
271 {
272         struct rb_node **p = &root->rb_node, *parent = NULL;
273 
274         while (*p) {
275                 struct htb_class *c;
276                 parent = *p;
277                 c = rb_entry(parent, struct htb_class, node[prio]);
278 
279                 if (cl->common.classid > c->common.classid)
280                         p = &parent->rb_right;
281                 else
282                         p = &parent->rb_left;
283         }
284         rb_link_node(&cl->node[prio], parent, p);
285         rb_insert_color(&cl->node[prio], root);
286 }
287 
288 /**
289  * htb_add_to_wait_tree - adds class to the event queue with delay
290  *
291  * The class is added to priority event queue to indicate that class will
292  * change its mode in cl->pq_key microseconds. Make sure that class is not
293  * already in the queue.
294  */
295 static void htb_add_to_wait_tree(struct htb_sched *q,
296                                  struct htb_class *cl, s64 delay)
297 {
298         struct rb_node **p = &q->hlevel[cl->level].wait_pq.rb_node, *parent = NULL;
299 
300         cl->pq_key = q->now + delay;
301         if (cl->pq_key == q->now)
302                 cl->pq_key++;
303 
304         /* update the nearest event cache */
305         if (q->near_ev_cache[cl->level] > cl->pq_key)
306                 q->near_ev_cache[cl->level] = cl->pq_key;
307 
308         while (*p) {
309                 struct htb_class *c;
310                 parent = *p;
311                 c = rb_entry(parent, struct htb_class, pq_node);
312                 if (cl->pq_key >= c->pq_key)
313                         p = &parent->rb_right;
314                 else
315                         p = &parent->rb_left;
316         }
317         rb_link_node(&cl->pq_node, parent, p);
318         rb_insert_color(&cl->pq_node, &q->hlevel[cl->level].wait_pq);
319 }
320 
321 /**
322  * htb_next_rb_node - finds next node in binary tree
323  *
324  * When we are past last key we return NULL.
325  * Average complexity is 2 steps per call.
326  */
327 static inline void htb_next_rb_node(struct rb_node **n)
328 {
329         *n = rb_next(*n);
330 }
331 
332 /**
333  * htb_add_class_to_row - add class to its row
334  *
335  * The class is added to row at priorities marked in mask.
336  * It does nothing if mask == 0.
337  */
338 static inline void htb_add_class_to_row(struct htb_sched *q,
339                                         struct htb_class *cl, int mask)
340 {
341         q->row_mask[cl->level] |= mask;
342         while (mask) {
343                 int prio = ffz(~mask);
344                 mask &= ~(1 << prio);
345                 htb_add_to_id_tree(&q->hlevel[cl->level].hprio[prio].row, cl, prio);
346         }
347 }
348 
349 /* If this triggers, it is a bug in this code, but it need not be fatal */
350 static void htb_safe_rb_erase(struct rb_node *rb, struct rb_root *root)
351 {
352         if (RB_EMPTY_NODE(rb)) {
353                 WARN_ON(1);
354         } else {
355                 rb_erase(rb, root);
356                 RB_CLEAR_NODE(rb);
357         }
358 }
359 
360 
361 /**
362  * htb_remove_class_from_row - removes class from its row
363  *
364  * The class is removed from row at priorities marked in mask.
365  * It does nothing if mask == 0.
366  */
367 static inline void htb_remove_class_from_row(struct htb_sched *q,
368                                                  struct htb_class *cl, int mask)
369 {
370         int m = 0;
371         struct htb_level *hlevel = &q->hlevel[cl->level];
372 
373         while (mask) {
374                 int prio = ffz(~mask);
375                 struct htb_prio *hprio = &hlevel->hprio[prio];
376 
377                 mask &= ~(1 << prio);
378                 if (hprio->ptr == cl->node + prio)
379                         htb_next_rb_node(&hprio->ptr);
380 
381                 htb_safe_rb_erase(cl->node + prio, &hprio->row);
382                 if (!hprio->row.rb_node)
383                         m |= 1 << prio;
384         }
385         q->row_mask[cl->level] &= ~m;
386 }
387 
388 /**
389  * htb_activate_prios - creates active classe's feed chain
390  *
391  * The class is connected to ancestors and/or appropriate rows
392  * for priorities it is participating on. cl->cmode must be new
393  * (activated) mode. It does nothing if cl->prio_activity == 0.
394  */
395 static void htb_activate_prios(struct htb_sched *q, struct htb_class *cl)
396 {
397         struct htb_class *p = cl->parent;
398         long m, mask = cl->prio_activity;
399 
400         while (cl->cmode == HTB_MAY_BORROW && p && mask) {
401                 m = mask;
402                 while (m) {
403                         int prio = ffz(~m);
404                         m &= ~(1 << prio);
405 
406                         if (p->un.inner.clprio[prio].feed.rb_node)
407                                 /* parent already has its feed in use so that
408                                  * reset bit in mask as parent is already ok
409                                  */
410                                 mask &= ~(1 << prio);
411 
412                         htb_add_to_id_tree(&p->un.inner.clprio[prio].feed, cl, prio);
413                 }
414                 p->prio_activity |= mask;
415                 cl = p;
416                 p = cl->parent;
417 
418         }
419         if (cl->cmode == HTB_CAN_SEND && mask)
420                 htb_add_class_to_row(q, cl, mask);
421 }
422 
423 /**
424  * htb_deactivate_prios - remove class from feed chain
425  *
426  * cl->cmode must represent old mode (before deactivation). It does
427  * nothing if cl->prio_activity == 0. Class is removed from all feed
428  * chains and rows.
429  */
430 static void htb_deactivate_prios(struct htb_sched *q, struct htb_class *cl)
431 {
432         struct htb_class *p = cl->parent;
433         long m, mask = cl->prio_activity;
434 
435         while (cl->cmode == HTB_MAY_BORROW && p && mask) {
436                 m = mask;
437                 mask = 0;
438                 while (m) {
439                         int prio = ffz(~m);
440                         m &= ~(1 << prio);
441 
442                         if (p->un.inner.clprio[prio].ptr == cl->node + prio) {
443                                 /* we are removing child which is pointed to from
444                                  * parent feed - forget the pointer but remember
445                                  * classid
446                                  */
447                                 p->un.inner.clprio[prio].last_ptr_id = cl->common.classid;
448                                 p->un.inner.clprio[prio].ptr = NULL;
449                         }
450 
451                         htb_safe_rb_erase(cl->node + prio,
452                                           &p->un.inner.clprio[prio].feed);
453 
454                         if (!p->un.inner.clprio[prio].feed.rb_node)
455                                 mask |= 1 << prio;
456                 }
457 
458                 p->prio_activity &= ~mask;
459                 cl = p;
460                 p = cl->parent;
461 
462         }
463         if (cl->cmode == HTB_CAN_SEND && mask)
464                 htb_remove_class_from_row(q, cl, mask);
465 }
466 
467 static inline s64 htb_lowater(const struct htb_class *cl)
468 {
469         if (htb_hysteresis)
470                 return cl->cmode != HTB_CANT_SEND ? -cl->cbuffer : 0;
471         else
472                 return 0;
473 }
474 static inline s64 htb_hiwater(const struct htb_class *cl)
475 {
476         if (htb_hysteresis)
477                 return cl->cmode == HTB_CAN_SEND ? -cl->buffer : 0;
478         else
479                 return 0;
480 }
481 
482 
483 /**
484  * htb_class_mode - computes and returns current class mode
485  *
486  * It computes cl's mode at time cl->t_c+diff and returns it. If mode
487  * is not HTB_CAN_SEND then cl->pq_key is updated to time difference
488  * from now to time when cl will change its state.
489  * Also it is worth to note that class mode doesn't change simply
490  * at cl->{c,}tokens == 0 but there can rather be hysteresis of
491  * 0 .. -cl->{c,}buffer range. It is meant to limit number of
492  * mode transitions per time unit. The speed gain is about 1/6.
493  */
494 static inline enum htb_cmode
495 htb_class_mode(struct htb_class *cl, s64 *diff)
496 {
497         s64 toks;
498 
499         if ((toks = (cl->ctokens + *diff)) < htb_lowater(cl)) {
500                 *diff = -toks;
501                 return HTB_CANT_SEND;
502         }
503 
504         if ((toks = (cl->tokens + *diff)) >= htb_hiwater(cl))
505                 return HTB_CAN_SEND;
506 
507         *diff = -toks;
508         return HTB_MAY_BORROW;
509 }
510 
511 /**
512  * htb_change_class_mode - changes classe's mode
513  *
514  * This should be the only way how to change classe's mode under normal
515  * cirsumstances. Routine will update feed lists linkage, change mode
516  * and add class to the wait event queue if appropriate. New mode should
517  * be different from old one and cl->pq_key has to be valid if changing
518  * to mode other than HTB_CAN_SEND (see htb_add_to_wait_tree).
519  */
520 static void
521 htb_change_class_mode(struct htb_sched *q, struct htb_class *cl, s64 *diff)
522 {
523         enum htb_cmode new_mode = htb_class_mode(cl, diff);
524 
525         if (new_mode == cl->cmode)
526                 return;
527 
528         if (cl->prio_activity) {        /* not necessary: speed optimization */
529                 if (cl->cmode != HTB_CANT_SEND)
530                         htb_deactivate_prios(q, cl);
531                 cl->cmode = new_mode;
532                 if (new_mode != HTB_CANT_SEND)
533                         htb_activate_prios(q, cl);
534         } else
535                 cl->cmode = new_mode;
536 }
537 
538 /**
539  * htb_activate - inserts leaf cl into appropriate active feeds
540  *
541  * Routine learns (new) priority of leaf and activates feed chain
542  * for the prio. It can be called on already active leaf safely.
543  * It also adds leaf into droplist.
544  */
545 static inline void htb_activate(struct htb_sched *q, struct htb_class *cl)
546 {
547         WARN_ON(cl->level || !cl->un.leaf.q || !cl->un.leaf.q->q.qlen);
548 
549         if (!cl->prio_activity) {
550                 cl->prio_activity = 1 << cl->prio;
551                 htb_activate_prios(q, cl);
552                 list_add_tail(&cl->un.leaf.drop_list,
553                               q->drops + cl->prio);
554         }
555 }
556 
557 /**
558  * htb_deactivate - remove leaf cl from active feeds
559  *
560  * Make sure that leaf is active. In the other words it can't be called
561  * with non-active leaf. It also removes class from the drop list.
562  */
563 static inline void htb_deactivate(struct htb_sched *q, struct htb_class *cl)
564 {
565         WARN_ON(!cl->prio_activity);
566 
567         htb_deactivate_prios(q, cl);
568         cl->prio_activity = 0;
569         list_del_init(&cl->un.leaf.drop_list);
570 }
571 
572 static int htb_enqueue(struct sk_buff *skb, struct Qdisc *sch)
573 {
574         int uninitialized_var(ret);
575         struct htb_sched *q = qdisc_priv(sch);
576         struct htb_class *cl = htb_classify(skb, sch, &ret);
577 
578         if (cl == HTB_DIRECT) {
579                 /* enqueue to helper queue */
580                 if (q->direct_queue.qlen < q->direct_qlen) {
581                         __skb_queue_tail(&q->direct_queue, skb);
582                         q->direct_pkts++;
583                 } else {
584                         return qdisc_drop(skb, sch);
585                 }
586 #ifdef CONFIG_NET_CLS_ACT
587         } else if (!cl) {
588                 if (ret & __NET_XMIT_BYPASS)
589                         qdisc_qstats_drop(sch);
590                 kfree_skb(skb);
591                 return ret;
592 #endif
593         } else if ((ret = qdisc_enqueue(skb, cl->un.leaf.q)) != NET_XMIT_SUCCESS) {
594                 if (net_xmit_drop_count(ret)) {
595                         qdisc_qstats_drop(sch);
596                         cl->qstats.drops++;
597                 }
598                 return ret;
599         } else {
600                 htb_activate(q, cl);
601         }
602 
603         qdisc_qstats_backlog_inc(sch, skb);
604         sch->q.qlen++;
605         return NET_XMIT_SUCCESS;
606 }
607 
608 static inline void htb_accnt_tokens(struct htb_class *cl, int bytes, s64 diff)
609 {
610         s64 toks = diff + cl->tokens;
611 
612         if (toks > cl->buffer)
613                 toks = cl->buffer;
614         toks -= (s64) psched_l2t_ns(&cl->rate, bytes);
615         if (toks <= -cl->mbuffer)
616                 toks = 1 - cl->mbuffer;
617 
618         cl->tokens = toks;
619 }
620 
621 static inline void htb_accnt_ctokens(struct htb_class *cl, int bytes, s64 diff)
622 {
623         s64 toks = diff + cl->ctokens;
624 
625         if (toks > cl->cbuffer)
626                 toks = cl->cbuffer;
627         toks -= (s64) psched_l2t_ns(&cl->ceil, bytes);
628         if (toks <= -cl->mbuffer)
629                 toks = 1 - cl->mbuffer;
630 
631         cl->ctokens = toks;
632 }
633 
634 /**
635  * htb_charge_class - charges amount "bytes" to leaf and ancestors
636  *
637  * Routine assumes that packet "bytes" long was dequeued from leaf cl
638  * borrowing from "level". It accounts bytes to ceil leaky bucket for
639  * leaf and all ancestors and to rate bucket for ancestors at levels
640  * "level" and higher. It also handles possible change of mode resulting
641  * from the update. Note that mode can also increase here (MAY_BORROW to
642  * CAN_SEND) because we can use more precise clock that event queue here.
643  * In such case we remove class from event queue first.
644  */
645 static void htb_charge_class(struct htb_sched *q, struct htb_class *cl,
646                              int level, struct sk_buff *skb)
647 {
648         int bytes = qdisc_pkt_len(skb);
649         enum htb_cmode old_mode;
650         s64 diff;
651 
652         while (cl) {
653                 diff = min_t(s64, q->now - cl->t_c, cl->mbuffer);
654                 if (cl->level >= level) {
655                         if (cl->level == level)
656                                 cl->xstats.lends++;
657                         htb_accnt_tokens(cl, bytes, diff);
658                 } else {
659                         cl->xstats.borrows++;
660                         cl->tokens += diff;     /* we moved t_c; update tokens */
661                 }
662                 htb_accnt_ctokens(cl, bytes, diff);
663                 cl->t_c = q->now;
664 
665                 old_mode = cl->cmode;
666                 diff = 0;
667                 htb_change_class_mode(q, cl, &diff);
668                 if (old_mode != cl->cmode) {
669                         if (old_mode != HTB_CAN_SEND)
670                                 htb_safe_rb_erase(&cl->pq_node, &q->hlevel[cl->level].wait_pq);
671                         if (cl->cmode != HTB_CAN_SEND)
672                                 htb_add_to_wait_tree(q, cl, diff);
673                 }
674 
675                 /* update basic stats except for leaves which are already updated */
676                 if (cl->level)
677                         bstats_update(&cl->bstats, skb);
678 
679                 cl = cl->parent;
680         }
681 }
682 
683 /**
684  * htb_do_events - make mode changes to classes at the level
685  *
686  * Scans event queue for pending events and applies them. Returns time of
687  * next pending event (0 for no event in pq, q->now for too many events).
688  * Note: Applied are events whose have cl->pq_key <= q->now.
689  */
690 static s64 htb_do_events(struct htb_sched *q, const int level,
691                          unsigned long start)
692 {
693         /* don't run for longer than 2 jiffies; 2 is used instead of
694          * 1 to simplify things when jiffy is going to be incremented
695          * too soon
696          */
697         unsigned long stop_at = start + 2;
698         struct rb_root *wait_pq = &q->hlevel[level].wait_pq;
699 
700         while (time_before(jiffies, stop_at)) {
701                 struct htb_class *cl;
702                 s64 diff;
703                 struct rb_node *p = rb_first(wait_pq);
704 
705                 if (!p)
706                         return 0;
707 
708                 cl = rb_entry(p, struct htb_class, pq_node);
709                 if (cl->pq_key > q->now)
710                         return cl->pq_key;
711 
712                 htb_safe_rb_erase(p, wait_pq);
713                 diff = min_t(s64, q->now - cl->t_c, cl->mbuffer);
714                 htb_change_class_mode(q, cl, &diff);
715                 if (cl->cmode != HTB_CAN_SEND)
716                         htb_add_to_wait_tree(q, cl, diff);
717         }
718 
719         /* too much load - let's continue after a break for scheduling */
720         if (!(q->warned & HTB_WARN_TOOMANYEVENTS)) {
721                 pr_warn("htb: too many events!\n");
722                 q->warned |= HTB_WARN_TOOMANYEVENTS;
723         }
724 
725         return q->now;
726 }
727 
728 /* Returns class->node+prio from id-tree where classe's id is >= id. NULL
729  * is no such one exists.
730  */
731 static struct rb_node *htb_id_find_next_upper(int prio, struct rb_node *n,
732                                               u32 id)
733 {
734         struct rb_node *r = NULL;
735         while (n) {
736                 struct htb_class *cl =
737                     rb_entry(n, struct htb_class, node[prio]);
738 
739                 if (id > cl->common.classid) {
740                         n = n->rb_right;
741                 } else if (id < cl->common.classid) {
742                         r = n;
743                         n = n->rb_left;
744                 } else {
745                         return n;
746                 }
747         }
748         return r;
749 }
750 
751 /**
752  * htb_lookup_leaf - returns next leaf class in DRR order
753  *
754  * Find leaf where current feed pointers points to.
755  */
756 static struct htb_class *htb_lookup_leaf(struct htb_prio *hprio, const int prio)
757 {
758         int i;
759         struct {
760                 struct rb_node *root;
761                 struct rb_node **pptr;
762                 u32 *pid;
763         } stk[TC_HTB_MAXDEPTH], *sp = stk;
764 
765         BUG_ON(!hprio->row.rb_node);
766         sp->root = hprio->row.rb_node;
767         sp->pptr = &hprio->ptr;
768         sp->pid = &hprio->last_ptr_id;
769 
770         for (i = 0; i < 65535; i++) {
771                 if (!*sp->pptr && *sp->pid) {
772                         /* ptr was invalidated but id is valid - try to recover
773                          * the original or next ptr
774                          */
775                         *sp->pptr =
776                             htb_id_find_next_upper(prio, sp->root, *sp->pid);
777                 }
778                 *sp->pid = 0;   /* ptr is valid now so that remove this hint as it
779                                  * can become out of date quickly
780                                  */
781                 if (!*sp->pptr) {       /* we are at right end; rewind & go up */
782                         *sp->pptr = sp->root;
783                         while ((*sp->pptr)->rb_left)
784                                 *sp->pptr = (*sp->pptr)->rb_left;
785                         if (sp > stk) {
786                                 sp--;
787                                 if (!*sp->pptr) {
788                                         WARN_ON(1);
789                                         return NULL;
790                                 }
791                                 htb_next_rb_node(sp->pptr);
792                         }
793                 } else {
794                         struct htb_class *cl;
795                         struct htb_prio *clp;
796 
797                         cl = rb_entry(*sp->pptr, struct htb_class, node[prio]);
798                         if (!cl->level)
799                                 return cl;
800                         clp = &cl->un.inner.clprio[prio];
801                         (++sp)->root = clp->feed.rb_node;
802                         sp->pptr = &clp->ptr;
803                         sp->pid = &clp->last_ptr_id;
804                 }
805         }
806         WARN_ON(1);
807         return NULL;
808 }
809 
810 /* dequeues packet at given priority and level; call only if
811  * you are sure that there is active class at prio/level
812  */
813 static struct sk_buff *htb_dequeue_tree(struct htb_sched *q, const int prio,
814                                         const int level)
815 {
816         struct sk_buff *skb = NULL;
817         struct htb_class *cl, *start;
818         struct htb_level *hlevel = &q->hlevel[level];
819         struct htb_prio *hprio = &hlevel->hprio[prio];
820 
821         /* look initial class up in the row */
822         start = cl = htb_lookup_leaf(hprio, prio);
823 
824         do {
825 next:
826                 if (unlikely(!cl))
827                         return NULL;
828 
829                 /* class can be empty - it is unlikely but can be true if leaf
830                  * qdisc drops packets in enqueue routine or if someone used
831                  * graft operation on the leaf since last dequeue;
832                  * simply deactivate and skip such class
833                  */
834                 if (unlikely(cl->un.leaf.q->q.qlen == 0)) {
835                         struct htb_class *next;
836                         htb_deactivate(q, cl);
837 
838                         /* row/level might become empty */
839                         if ((q->row_mask[level] & (1 << prio)) == 0)
840                                 return NULL;
841 
842                         next = htb_lookup_leaf(hprio, prio);
843 
844                         if (cl == start)        /* fix start if we just deleted it */
845                                 start = next;
846                         cl = next;
847                         goto next;
848                 }
849 
850                 skb = cl->un.leaf.q->dequeue(cl->un.leaf.q);
851                 if (likely(skb != NULL))
852                         break;
853 
854                 qdisc_warn_nonwc("htb", cl->un.leaf.q);
855                 htb_next_rb_node(level ? &cl->parent->un.inner.clprio[prio].ptr:
856                                          &q->hlevel[0].hprio[prio].ptr);
857                 cl = htb_lookup_leaf(hprio, prio);
858 
859         } while (cl != start);
860 
861         if (likely(skb != NULL)) {
862                 bstats_update(&cl->bstats, skb);
863                 cl->un.leaf.deficit[level] -= qdisc_pkt_len(skb);
864                 if (cl->un.leaf.deficit[level] < 0) {
865                         cl->un.leaf.deficit[level] += cl->quantum;
866                         htb_next_rb_node(level ? &cl->parent->un.inner.clprio[prio].ptr :
867                                                  &q->hlevel[0].hprio[prio].ptr);
868                 }
869                 /* this used to be after charge_class but this constelation
870                  * gives us slightly better performance
871                  */
872                 if (!cl->un.leaf.q->q.qlen)
873                         htb_deactivate(q, cl);
874                 htb_charge_class(q, cl, level, skb);
875         }
876         return skb;
877 }
878 
879 static struct sk_buff *htb_dequeue(struct Qdisc *sch)
880 {
881         struct sk_buff *skb;
882         struct htb_sched *q = qdisc_priv(sch);
883         int level;
884         s64 next_event;
885         unsigned long start_at;
886 
887         /* try to dequeue direct packets as high prio (!) to minimize cpu work */
888         skb = __skb_dequeue(&q->direct_queue);
889         if (skb != NULL) {
890 ok:
891                 qdisc_bstats_update(sch, skb);
892                 qdisc_unthrottled(sch);
893                 qdisc_qstats_backlog_dec(sch, skb);
894                 sch->q.qlen--;
895                 return skb;
896         }
897 
898         if (!sch->q.qlen)
899                 goto fin;
900         q->now = ktime_get_ns();
901         start_at = jiffies;
902 
903         next_event = q->now + 5LLU * NSEC_PER_SEC;
904 
905         for (level = 0; level < TC_HTB_MAXDEPTH; level++) {
906                 /* common case optimization - skip event handler quickly */
907                 int m;
908                 s64 event = q->near_ev_cache[level];
909 
910                 if (q->now >= event) {
911                         event = htb_do_events(q, level, start_at);
912                         if (!event)
913                                 event = q->now + NSEC_PER_SEC;
914                         q->near_ev_cache[level] = event;
915                 }
916 
917                 if (next_event > event)
918                         next_event = event;
919 
920                 m = ~q->row_mask[level];
921                 while (m != (int)(-1)) {
922                         int prio = ffz(m);
923 
924                         m |= 1 << prio;
925                         skb = htb_dequeue_tree(q, prio, level);
926                         if (likely(skb != NULL))
927                                 goto ok;
928                 }
929         }
930         qdisc_qstats_overlimit(sch);
931         if (likely(next_event > q->now)) {
932                 if (!test_bit(__QDISC_STATE_DEACTIVATED,
933                               &qdisc_root_sleeping(q->watchdog.qdisc)->state)) {
934                         ktime_t time = ns_to_ktime(next_event);
935                         qdisc_throttled(q->watchdog.qdisc);
936                         hrtimer_start(&q->watchdog.timer, time,
937                                       HRTIMER_MODE_ABS_PINNED);
938                 }
939         } else {
940                 schedule_work(&q->work);
941         }
942 fin:
943         return skb;
944 }
945 
946 /* try to drop from each class (by prio) until one succeed */
947 static unsigned int htb_drop(struct Qdisc *sch)
948 {
949         struct htb_sched *q = qdisc_priv(sch);
950         int prio;
951 
952         for (prio = TC_HTB_NUMPRIO - 1; prio >= 0; prio--) {
953                 struct list_head *p;
954                 list_for_each(p, q->drops + prio) {
955                         struct htb_class *cl = list_entry(p, struct htb_class,
956                                                           un.leaf.drop_list);
957                         unsigned int len;
958                         if (cl->un.leaf.q->ops->drop &&
959                             (len = cl->un.leaf.q->ops->drop(cl->un.leaf.q))) {
960                                 sch->qstats.backlog -= len;
961                                 sch->q.qlen--;
962                                 if (!cl->un.leaf.q->q.qlen)
963                                         htb_deactivate(q, cl);
964                                 return len;
965                         }
966                 }
967         }
968         return 0;
969 }
970 
971 /* reset all classes */
972 /* always caled under BH & queue lock */
973 static void htb_reset(struct Qdisc *sch)
974 {
975         struct htb_sched *q = qdisc_priv(sch);
976         struct htb_class *cl;
977         unsigned int i;
978 
979         for (i = 0; i < q->clhash.hashsize; i++) {
980                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
981                         if (cl->level)
982                                 memset(&cl->un.inner, 0, sizeof(cl->un.inner));
983                         else {
984                                 if (cl->un.leaf.q)
985                                         qdisc_reset(cl->un.leaf.q);
986                                 INIT_LIST_HEAD(&cl->un.leaf.drop_list);
987                         }
988                         cl->prio_activity = 0;
989                         cl->cmode = HTB_CAN_SEND;
990                 }
991         }
992         qdisc_watchdog_cancel(&q->watchdog);
993         __skb_queue_purge(&q->direct_queue);
994         sch->q.qlen = 0;
995         sch->qstats.backlog = 0;
996         memset(q->hlevel, 0, sizeof(q->hlevel));
997         memset(q->row_mask, 0, sizeof(q->row_mask));
998         for (i = 0; i < TC_HTB_NUMPRIO; i++)
999                 INIT_LIST_HEAD(q->drops + i);
1000 }
1001 
1002 static const struct nla_policy htb_policy[TCA_HTB_MAX + 1] = {
1003         [TCA_HTB_PARMS] = { .len = sizeof(struct tc_htb_opt) },
1004         [TCA_HTB_INIT]  = { .len = sizeof(struct tc_htb_glob) },
1005         [TCA_HTB_CTAB]  = { .type = NLA_BINARY, .len = TC_RTAB_SIZE },
1006         [TCA_HTB_RTAB]  = { .type = NLA_BINARY, .len = TC_RTAB_SIZE },
1007         [TCA_HTB_DIRECT_QLEN] = { .type = NLA_U32 },
1008         [TCA_HTB_RATE64] = { .type = NLA_U64 },
1009         [TCA_HTB_CEIL64] = { .type = NLA_U64 },
1010 };
1011 
1012 static void htb_work_func(struct work_struct *work)
1013 {
1014         struct htb_sched *q = container_of(work, struct htb_sched, work);
1015         struct Qdisc *sch = q->watchdog.qdisc;
1016 
1017         __netif_schedule(qdisc_root(sch));
1018 }
1019 
1020 static int htb_init(struct Qdisc *sch, struct nlattr *opt)
1021 {
1022         struct htb_sched *q = qdisc_priv(sch);
1023         struct nlattr *tb[TCA_HTB_MAX + 1];
1024         struct tc_htb_glob *gopt;
1025         int err;
1026         int i;
1027 
1028         if (!opt)
1029                 return -EINVAL;
1030 
1031         err = nla_parse_nested(tb, TCA_HTB_MAX, opt, htb_policy);
1032         if (err < 0)
1033                 return err;
1034 
1035         if (!tb[TCA_HTB_INIT])
1036                 return -EINVAL;
1037 
1038         gopt = nla_data(tb[TCA_HTB_INIT]);
1039         if (gopt->version != HTB_VER >> 16)
1040                 return -EINVAL;
1041 
1042         err = qdisc_class_hash_init(&q->clhash);
1043         if (err < 0)
1044                 return err;
1045         for (i = 0; i < TC_HTB_NUMPRIO; i++)
1046                 INIT_LIST_HEAD(q->drops + i);
1047 
1048         qdisc_watchdog_init(&q->watchdog, sch);
1049         INIT_WORK(&q->work, htb_work_func);
1050         __skb_queue_head_init(&q->direct_queue);
1051 
1052         if (tb[TCA_HTB_DIRECT_QLEN])
1053                 q->direct_qlen = nla_get_u32(tb[TCA_HTB_DIRECT_QLEN]);
1054         else
1055                 q->direct_qlen = qdisc_dev(sch)->tx_queue_len;
1056 
1057         if ((q->rate2quantum = gopt->rate2quantum) < 1)
1058                 q->rate2quantum = 1;
1059         q->defcls = gopt->defcls;
1060 
1061         return 0;
1062 }
1063 
1064 static int htb_dump(struct Qdisc *sch, struct sk_buff *skb)
1065 {
1066         struct htb_sched *q = qdisc_priv(sch);
1067         struct nlattr *nest;
1068         struct tc_htb_glob gopt;
1069 
1070         /* Its safe to not acquire qdisc lock. As we hold RTNL,
1071          * no change can happen on the qdisc parameters.
1072          */
1073 
1074         gopt.direct_pkts = q->direct_pkts;
1075         gopt.version = HTB_VER;
1076         gopt.rate2quantum = q->rate2quantum;
1077         gopt.defcls = q->defcls;
1078         gopt.debug = 0;
1079 
1080         nest = nla_nest_start(skb, TCA_OPTIONS);
1081         if (nest == NULL)
1082                 goto nla_put_failure;
1083         if (nla_put(skb, TCA_HTB_INIT, sizeof(gopt), &gopt) ||
1084             nla_put_u32(skb, TCA_HTB_DIRECT_QLEN, q->direct_qlen))
1085                 goto nla_put_failure;
1086 
1087         return nla_nest_end(skb, nest);
1088 
1089 nla_put_failure:
1090         nla_nest_cancel(skb, nest);
1091         return -1;
1092 }
1093 
1094 static int htb_dump_class(struct Qdisc *sch, unsigned long arg,
1095                           struct sk_buff *skb, struct tcmsg *tcm)
1096 {
1097         struct htb_class *cl = (struct htb_class *)arg;
1098         struct nlattr *nest;
1099         struct tc_htb_opt opt;
1100 
1101         /* Its safe to not acquire qdisc lock. As we hold RTNL,
1102          * no change can happen on the class parameters.
1103          */
1104         tcm->tcm_parent = cl->parent ? cl->parent->common.classid : TC_H_ROOT;
1105         tcm->tcm_handle = cl->common.classid;
1106         if (!cl->level && cl->un.leaf.q)
1107                 tcm->tcm_info = cl->un.leaf.q->handle;
1108 
1109         nest = nla_nest_start(skb, TCA_OPTIONS);
1110         if (nest == NULL)
1111                 goto nla_put_failure;
1112 
1113         memset(&opt, 0, sizeof(opt));
1114 
1115         psched_ratecfg_getrate(&opt.rate, &cl->rate);
1116         opt.buffer = PSCHED_NS2TICKS(cl->buffer);
1117         psched_ratecfg_getrate(&opt.ceil, &cl->ceil);
1118         opt.cbuffer = PSCHED_NS2TICKS(cl->cbuffer);
1119         opt.quantum = cl->quantum;
1120         opt.prio = cl->prio;
1121         opt.level = cl->level;
1122         if (nla_put(skb, TCA_HTB_PARMS, sizeof(opt), &opt))
1123                 goto nla_put_failure;
1124         if ((cl->rate.rate_bytes_ps >= (1ULL << 32)) &&
1125             nla_put_u64(skb, TCA_HTB_RATE64, cl->rate.rate_bytes_ps))
1126                 goto nla_put_failure;
1127         if ((cl->ceil.rate_bytes_ps >= (1ULL << 32)) &&
1128             nla_put_u64(skb, TCA_HTB_CEIL64, cl->ceil.rate_bytes_ps))
1129                 goto nla_put_failure;
1130 
1131         return nla_nest_end(skb, nest);
1132 
1133 nla_put_failure:
1134         nla_nest_cancel(skb, nest);
1135         return -1;
1136 }
1137 
1138 static int
1139 htb_dump_class_stats(struct Qdisc *sch, unsigned long arg, struct gnet_dump *d)
1140 {
1141         struct htb_class *cl = (struct htb_class *)arg;
1142         __u32 qlen = 0;
1143 
1144         if (!cl->level && cl->un.leaf.q)
1145                 qlen = cl->un.leaf.q->q.qlen;
1146         cl->xstats.tokens = PSCHED_NS2TICKS(cl->tokens);
1147         cl->xstats.ctokens = PSCHED_NS2TICKS(cl->ctokens);
1148 
1149         if (gnet_stats_copy_basic(d, NULL, &cl->bstats) < 0 ||
1150             gnet_stats_copy_rate_est(d, NULL, &cl->rate_est) < 0 ||
1151             gnet_stats_copy_queue(d, NULL, &cl->qstats, qlen) < 0)
1152                 return -1;
1153 
1154         return gnet_stats_copy_app(d, &cl->xstats, sizeof(cl->xstats));
1155 }
1156 
1157 static int htb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
1158                      struct Qdisc **old)
1159 {
1160         struct htb_class *cl = (struct htb_class *)arg;
1161 
1162         if (cl->level)
1163                 return -EINVAL;
1164         if (new == NULL &&
1165             (new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
1166                                      cl->common.classid)) == NULL)
1167                 return -ENOBUFS;
1168 
1169         *old = qdisc_replace(sch, new, &cl->un.leaf.q);
1170         return 0;
1171 }
1172 
1173 static struct Qdisc *htb_leaf(struct Qdisc *sch, unsigned long arg)
1174 {
1175         struct htb_class *cl = (struct htb_class *)arg;
1176         return !cl->level ? cl->un.leaf.q : NULL;
1177 }
1178 
1179 static void htb_qlen_notify(struct Qdisc *sch, unsigned long arg)
1180 {
1181         struct htb_class *cl = (struct htb_class *)arg;
1182 
1183         if (cl->un.leaf.q->q.qlen == 0)
1184                 htb_deactivate(qdisc_priv(sch), cl);
1185 }
1186 
1187 static unsigned long htb_get(struct Qdisc *sch, u32 classid)
1188 {
1189         struct htb_class *cl = htb_find(classid, sch);
1190         if (cl)
1191                 cl->refcnt++;
1192         return (unsigned long)cl;
1193 }
1194 
1195 static inline int htb_parent_last_child(struct htb_class *cl)
1196 {
1197         if (!cl->parent)
1198                 /* the root class */
1199                 return 0;
1200         if (cl->parent->children > 1)
1201                 /* not the last child */
1202                 return 0;
1203         return 1;
1204 }
1205 
1206 static void htb_parent_to_leaf(struct htb_sched *q, struct htb_class *cl,
1207                                struct Qdisc *new_q)
1208 {
1209         struct htb_class *parent = cl->parent;
1210 
1211         WARN_ON(cl->level || !cl->un.leaf.q || cl->prio_activity);
1212 
1213         if (parent->cmode != HTB_CAN_SEND)
1214                 htb_safe_rb_erase(&parent->pq_node,
1215                                   &q->hlevel[parent->level].wait_pq);
1216 
1217         parent->level = 0;
1218         memset(&parent->un.inner, 0, sizeof(parent->un.inner));
1219         INIT_LIST_HEAD(&parent->un.leaf.drop_list);
1220         parent->un.leaf.q = new_q ? new_q : &noop_qdisc;
1221         parent->tokens = parent->buffer;
1222         parent->ctokens = parent->cbuffer;
1223         parent->t_c = ktime_get_ns();
1224         parent->cmode = HTB_CAN_SEND;
1225 }
1226 
1227 static void htb_destroy_class(struct Qdisc *sch, struct htb_class *cl)
1228 {
1229         if (!cl->level) {
1230                 WARN_ON(!cl->un.leaf.q);
1231                 qdisc_destroy(cl->un.leaf.q);
1232         }
1233         gen_kill_estimator(&cl->bstats, &cl->rate_est);
1234         tcf_destroy_chain(&cl->filter_list);
1235         kfree(cl);
1236 }
1237 
1238 static void htb_destroy(struct Qdisc *sch)
1239 {
1240         struct htb_sched *q = qdisc_priv(sch);
1241         struct hlist_node *next;
1242         struct htb_class *cl;
1243         unsigned int i;
1244 
1245         cancel_work_sync(&q->work);
1246         qdisc_watchdog_cancel(&q->watchdog);
1247         /* This line used to be after htb_destroy_class call below
1248          * and surprisingly it worked in 2.4. But it must precede it
1249          * because filter need its target class alive to be able to call
1250          * unbind_filter on it (without Oops).
1251          */
1252         tcf_destroy_chain(&q->filter_list);
1253 
1254         for (i = 0; i < q->clhash.hashsize; i++) {
1255                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode)
1256                         tcf_destroy_chain(&cl->filter_list);
1257         }
1258         for (i = 0; i < q->clhash.hashsize; i++) {
1259                 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],
1260                                           common.hnode)
1261                         htb_destroy_class(sch, cl);
1262         }
1263         qdisc_class_hash_destroy(&q->clhash);
1264         __skb_queue_purge(&q->direct_queue);
1265 }
1266 
1267 static int htb_delete(struct Qdisc *sch, unsigned long arg)
1268 {
1269         struct htb_sched *q = qdisc_priv(sch);
1270         struct htb_class *cl = (struct htb_class *)arg;
1271         struct Qdisc *new_q = NULL;
1272         int last_child = 0;
1273 
1274         /* TODO: why don't allow to delete subtree ? references ? does
1275          * tc subsys guarantee us that in htb_destroy it holds no class
1276          * refs so that we can remove children safely there ?
1277          */
1278         if (cl->children || cl->filter_cnt)
1279                 return -EBUSY;
1280 
1281         if (!cl->level && htb_parent_last_child(cl)) {
1282                 new_q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
1283                                           cl->parent->common.classid);
1284                 last_child = 1;
1285         }
1286 
1287         sch_tree_lock(sch);
1288 
1289         if (!cl->level) {
1290                 unsigned int qlen = cl->un.leaf.q->q.qlen;
1291                 unsigned int backlog = cl->un.leaf.q->qstats.backlog;
1292 
1293                 qdisc_reset(cl->un.leaf.q);
1294                 qdisc_tree_reduce_backlog(cl->un.leaf.q, qlen, backlog);
1295         }
1296 
1297         /* delete from hash and active; remainder in destroy_class */
1298         qdisc_class_hash_remove(&q->clhash, &cl->common);
1299         if (cl->parent)
1300                 cl->parent->children--;
1301 
1302         if (cl->prio_activity)
1303                 htb_deactivate(q, cl);
1304 
1305         if (cl->cmode != HTB_CAN_SEND)
1306                 htb_safe_rb_erase(&cl->pq_node,
1307                                   &q->hlevel[cl->level].wait_pq);
1308 
1309         if (last_child)
1310                 htb_parent_to_leaf(q, cl, new_q);
1311 
1312         BUG_ON(--cl->refcnt == 0);
1313         /*
1314          * This shouldn't happen: we "hold" one cops->get() when called
1315          * from tc_ctl_tclass; the destroy method is done from cops->put().
1316          */
1317 
1318         sch_tree_unlock(sch);
1319         return 0;
1320 }
1321 
1322 static void htb_put(struct Qdisc *sch, unsigned long arg)
1323 {
1324         struct htb_class *cl = (struct htb_class *)arg;
1325 
1326         if (--cl->refcnt == 0)
1327                 htb_destroy_class(sch, cl);
1328 }
1329 
1330 static int htb_change_class(struct Qdisc *sch, u32 classid,
1331                             u32 parentid, struct nlattr **tca,
1332                             unsigned long *arg)
1333 {
1334         int err = -EINVAL;
1335         struct htb_sched *q = qdisc_priv(sch);
1336         struct htb_class *cl = (struct htb_class *)*arg, *parent;
1337         struct nlattr *opt = tca[TCA_OPTIONS];
1338         struct nlattr *tb[TCA_HTB_MAX + 1];
1339         struct tc_htb_opt *hopt;
1340         u64 rate64, ceil64;
1341 
1342         /* extract all subattrs from opt attr */
1343         if (!opt)
1344                 goto failure;
1345 
1346         err = nla_parse_nested(tb, TCA_HTB_MAX, opt, htb_policy);
1347         if (err < 0)
1348                 goto failure;
1349 
1350         err = -EINVAL;
1351         if (tb[TCA_HTB_PARMS] == NULL)
1352                 goto failure;
1353 
1354         parent = parentid == TC_H_ROOT ? NULL : htb_find(parentid, sch);
1355 
1356         hopt = nla_data(tb[TCA_HTB_PARMS]);
1357         if (!hopt->rate.rate || !hopt->ceil.rate)
1358                 goto failure;
1359 
1360         /* Keeping backward compatible with rate_table based iproute2 tc */
1361         if (hopt->rate.linklayer == TC_LINKLAYER_UNAWARE)
1362                 qdisc_put_rtab(qdisc_get_rtab(&hopt->rate, tb[TCA_HTB_RTAB]));
1363 
1364         if (hopt->ceil.linklayer == TC_LINKLAYER_UNAWARE)
1365                 qdisc_put_rtab(qdisc_get_rtab(&hopt->ceil, tb[TCA_HTB_CTAB]));
1366 
1367         if (!cl) {              /* new class */
1368                 struct Qdisc *new_q;
1369                 int prio;
1370                 struct {
1371                         struct nlattr           nla;
1372                         struct gnet_estimator   opt;
1373                 } est = {
1374                         .nla = {
1375                                 .nla_len        = nla_attr_size(sizeof(est.opt)),
1376                                 .nla_type       = TCA_RATE,
1377                         },
1378                         .opt = {
1379                                 /* 4s interval, 16s averaging constant */
1380                                 .interval       = 2,
1381                                 .ewma_log       = 2,
1382                         },
1383                 };
1384 
1385                 /* check for valid classid */
1386                 if (!classid || TC_H_MAJ(classid ^ sch->handle) ||
1387                     htb_find(classid, sch))
1388                         goto failure;
1389 
1390                 /* check maximal depth */
1391                 if (parent && parent->parent && parent->parent->level < 2) {
1392                         pr_err("htb: tree is too deep\n");
1393                         goto failure;
1394                 }
1395                 err = -ENOBUFS;
1396                 cl = kzalloc(sizeof(*cl), GFP_KERNEL);
1397                 if (!cl)
1398                         goto failure;
1399 
1400                 if (htb_rate_est || tca[TCA_RATE]) {
1401                         err = gen_new_estimator(&cl->bstats, NULL,
1402                                                 &cl->rate_est,
1403                                                 qdisc_root_sleeping_lock(sch),
1404                                                 tca[TCA_RATE] ? : &est.nla);
1405                         if (err) {
1406                                 kfree(cl);
1407                                 goto failure;
1408                         }
1409                 }
1410 
1411                 cl->refcnt = 1;
1412                 cl->children = 0;
1413                 INIT_LIST_HEAD(&cl->un.leaf.drop_list);
1414                 RB_CLEAR_NODE(&cl->pq_node);
1415 
1416                 for (prio = 0; prio < TC_HTB_NUMPRIO; prio++)
1417                         RB_CLEAR_NODE(&cl->node[prio]);
1418 
1419                 /* create leaf qdisc early because it uses kmalloc(GFP_KERNEL)
1420                  * so that can't be used inside of sch_tree_lock
1421                  * -- thanks to Karlis Peisenieks
1422                  */
1423                 new_q = qdisc_create_dflt(sch->dev_queue,
1424                                           &pfifo_qdisc_ops, classid);
1425                 sch_tree_lock(sch);
1426                 if (parent && !parent->level) {
1427                         unsigned int qlen = parent->un.leaf.q->q.qlen;
1428                         unsigned int backlog = parent->un.leaf.q->qstats.backlog;
1429 
1430                         /* turn parent into inner node */
1431                         qdisc_reset(parent->un.leaf.q);
1432                         qdisc_tree_reduce_backlog(parent->un.leaf.q, qlen, backlog);
1433                         qdisc_destroy(parent->un.leaf.q);
1434                         if (parent->prio_activity)
1435                                 htb_deactivate(q, parent);
1436 
1437                         /* remove from evt list because of level change */
1438                         if (parent->cmode != HTB_CAN_SEND) {
1439                                 htb_safe_rb_erase(&parent->pq_node, &q->hlevel[0].wait_pq);
1440                                 parent->cmode = HTB_CAN_SEND;
1441                         }
1442                         parent->level = (parent->parent ? parent->parent->level
1443                                          : TC_HTB_MAXDEPTH) - 1;
1444                         memset(&parent->un.inner, 0, sizeof(parent->un.inner));
1445                 }
1446                 /* leaf (we) needs elementary qdisc */
1447                 cl->un.leaf.q = new_q ? new_q : &noop_qdisc;
1448 
1449                 cl->common.classid = classid;
1450                 cl->parent = parent;
1451 
1452                 /* set class to be in HTB_CAN_SEND state */
1453                 cl->tokens = PSCHED_TICKS2NS(hopt->buffer);
1454                 cl->ctokens = PSCHED_TICKS2NS(hopt->cbuffer);
1455                 cl->mbuffer = 60ULL * NSEC_PER_SEC;     /* 1min */
1456                 cl->t_c = ktime_get_ns();
1457                 cl->cmode = HTB_CAN_SEND;
1458 
1459                 /* attach to the hash list and parent's family */
1460                 qdisc_class_hash_insert(&q->clhash, &cl->common);
1461                 if (parent)
1462                         parent->children++;
1463         } else {
1464                 if (tca[TCA_RATE]) {
1465                         spinlock_t *lock = qdisc_root_sleeping_lock(sch);
1466 
1467                         err = gen_replace_estimator(&cl->bstats, NULL,
1468                                                     &cl->rate_est,
1469                                                     lock,
1470                                                     tca[TCA_RATE]);
1471                         if (err)
1472                                 return err;
1473                 }
1474                 sch_tree_lock(sch);
1475         }
1476 
1477         rate64 = tb[TCA_HTB_RATE64] ? nla_get_u64(tb[TCA_HTB_RATE64]) : 0;
1478 
1479         ceil64 = tb[TCA_HTB_CEIL64] ? nla_get_u64(tb[TCA_HTB_CEIL64]) : 0;
1480 
1481         psched_ratecfg_precompute(&cl->rate, &hopt->rate, rate64);
1482         psched_ratecfg_precompute(&cl->ceil, &hopt->ceil, ceil64);
1483 
1484         /* it used to be a nasty bug here, we have to check that node
1485          * is really leaf before changing cl->un.leaf !
1486          */
1487         if (!cl->level) {
1488                 u64 quantum = cl->rate.rate_bytes_ps;
1489 
1490                 do_div(quantum, q->rate2quantum);
1491                 cl->quantum = min_t(u64, quantum, INT_MAX);
1492 
1493                 if (!hopt->quantum && cl->quantum < 1000) {
1494                         pr_warn("HTB: quantum of class %X is small. Consider r2q change.\n",
1495                                 cl->common.classid);
1496                         cl->quantum = 1000;
1497                 }
1498                 if (!hopt->quantum && cl->quantum > 200000) {
1499                         pr_warn("HTB: quantum of class %X is big. Consider r2q change.\n",
1500                                 cl->common.classid);
1501                         cl->quantum = 200000;
1502                 }
1503                 if (hopt->quantum)
1504                         cl->quantum = hopt->quantum;
1505                 if ((cl->prio = hopt->prio) >= TC_HTB_NUMPRIO)
1506                         cl->prio = TC_HTB_NUMPRIO - 1;
1507         }
1508 
1509         cl->buffer = PSCHED_TICKS2NS(hopt->buffer);
1510         cl->cbuffer = PSCHED_TICKS2NS(hopt->cbuffer);
1511 
1512         sch_tree_unlock(sch);
1513 
1514         qdisc_class_hash_grow(sch, &q->clhash);
1515 
1516         *arg = (unsigned long)cl;
1517         return 0;
1518 
1519 failure:
1520         return err;
1521 }
1522 
1523 static struct tcf_proto __rcu **htb_find_tcf(struct Qdisc *sch,
1524                                              unsigned long arg)
1525 {
1526         struct htb_sched *q = qdisc_priv(sch);
1527         struct htb_class *cl = (struct htb_class *)arg;
1528         struct tcf_proto __rcu **fl = cl ? &cl->filter_list : &q->filter_list;
1529 
1530         return fl;
1531 }
1532 
1533 static unsigned long htb_bind_filter(struct Qdisc *sch, unsigned long parent,
1534                                      u32 classid)
1535 {
1536         struct htb_class *cl = htb_find(classid, sch);
1537 
1538         /*if (cl && !cl->level) return 0;
1539          * The line above used to be there to prevent attaching filters to
1540          * leaves. But at least tc_index filter uses this just to get class
1541          * for other reasons so that we have to allow for it.
1542          * ----
1543          * 19.6.2002 As Werner explained it is ok - bind filter is just
1544          * another way to "lock" the class - unlike "get" this lock can
1545          * be broken by class during destroy IIUC.
1546          */
1547         if (cl)
1548                 cl->filter_cnt++;
1549         return (unsigned long)cl;
1550 }
1551 
1552 static void htb_unbind_filter(struct Qdisc *sch, unsigned long arg)
1553 {
1554         struct htb_class *cl = (struct htb_class *)arg;
1555 
1556         if (cl)
1557                 cl->filter_cnt--;
1558 }
1559 
1560 static void htb_walk(struct Qdisc *sch, struct qdisc_walker *arg)
1561 {
1562         struct htb_sched *q = qdisc_priv(sch);
1563         struct htb_class *cl;
1564         unsigned int i;
1565 
1566         if (arg->stop)
1567                 return;
1568 
1569         for (i = 0; i < q->clhash.hashsize; i++) {
1570                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
1571                         if (arg->count < arg->skip) {
1572                                 arg->count++;
1573                                 continue;
1574                         }
1575                         if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
1576                                 arg->stop = 1;
1577                                 return;
1578                         }
1579                         arg->count++;
1580                 }
1581         }
1582 }
1583 
1584 static const struct Qdisc_class_ops htb_class_ops = {
1585         .graft          =       htb_graft,
1586         .leaf           =       htb_leaf,
1587         .qlen_notify    =       htb_qlen_notify,
1588         .get            =       htb_get,
1589         .put            =       htb_put,
1590         .change         =       htb_change_class,
1591         .delete         =       htb_delete,
1592         .walk           =       htb_walk,
1593         .tcf_chain      =       htb_find_tcf,
1594         .bind_tcf       =       htb_bind_filter,
1595         .unbind_tcf     =       htb_unbind_filter,
1596         .dump           =       htb_dump_class,
1597         .dump_stats     =       htb_dump_class_stats,
1598 };
1599 
1600 static struct Qdisc_ops htb_qdisc_ops __read_mostly = {
1601         .cl_ops         =       &htb_class_ops,
1602         .id             =       "htb",
1603         .priv_size      =       sizeof(struct htb_sched),
1604         .enqueue        =       htb_enqueue,
1605         .dequeue        =       htb_dequeue,
1606         .peek           =       qdisc_peek_dequeued,
1607         .drop           =       htb_drop,
1608         .init           =       htb_init,
1609         .reset          =       htb_reset,
1610         .destroy        =       htb_destroy,
1611         .dump           =       htb_dump,
1612         .owner          =       THIS_MODULE,
1613 };
1614 
1615 static int __init htb_module_init(void)
1616 {
1617         return register_qdisc(&htb_qdisc_ops);
1618 }
1619 static void __exit htb_module_exit(void)
1620 {
1621         unregister_qdisc(&htb_qdisc_ops);
1622 }
1623 
1624 module_init(htb_module_init)
1625 module_exit(htb_module_exit)
1626 MODULE_LICENSE("GPL");
1627 

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