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Linux/net/sched/sch_htb.c

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

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