Loading...
1/*
2 * 2002-10-18 written by Jim Houston jim.houston@ccur.com
3 * Copyright (C) 2002 by Concurrent Computer Corporation
4 * Distributed under the GNU GPL license version 2.
5 *
6 * Modified by George Anzinger to reuse immediately and to use
7 * find bit instructions. Also removed _irq on spinlocks.
8 *
9 * Modified by Nadia Derbey to make it RCU safe.
10 *
11 * Small id to pointer translation service.
12 *
13 * It uses a radix tree like structure as a sparse array indexed
14 * by the id to obtain the pointer. The bitmap makes allocating
15 * a new id quick.
16 *
17 * You call it to allocate an id (an int) an associate with that id a
18 * pointer or what ever, we treat it as a (void *). You can pass this
19 * id to a user for him to pass back at a later time. You then pass
20 * that id to this code and it returns your pointer.
21
22 * You can release ids at any time. When all ids are released, most of
23 * the memory is returned (we keep IDR_FREE_MAX) in a local pool so we
24 * don't need to go to the memory "store" during an id allocate, just
25 * so you don't need to be too concerned about locking and conflicts
26 * with the slab allocator.
27 */
28
29#ifndef TEST // to test in user space...
30#include <linux/slab.h>
31#include <linux/init.h>
32#include <linux/module.h>
33#endif
34#include <linux/err.h>
35#include <linux/string.h>
36#include <linux/idr.h>
37#include <linux/spinlock.h>
38
39static struct kmem_cache *idr_layer_cache;
40static DEFINE_SPINLOCK(simple_ida_lock);
41
42static struct idr_layer *get_from_free_list(struct idr *idp)
43{
44 struct idr_layer *p;
45 unsigned long flags;
46
47 spin_lock_irqsave(&idp->lock, flags);
48 if ((p = idp->id_free)) {
49 idp->id_free = p->ary[0];
50 idp->id_free_cnt--;
51 p->ary[0] = NULL;
52 }
53 spin_unlock_irqrestore(&idp->lock, flags);
54 return(p);
55}
56
57static void idr_layer_rcu_free(struct rcu_head *head)
58{
59 struct idr_layer *layer;
60
61 layer = container_of(head, struct idr_layer, rcu_head);
62 kmem_cache_free(idr_layer_cache, layer);
63}
64
65static inline void free_layer(struct idr_layer *p)
66{
67 call_rcu(&p->rcu_head, idr_layer_rcu_free);
68}
69
70/* only called when idp->lock is held */
71static void __move_to_free_list(struct idr *idp, struct idr_layer *p)
72{
73 p->ary[0] = idp->id_free;
74 idp->id_free = p;
75 idp->id_free_cnt++;
76}
77
78static void move_to_free_list(struct idr *idp, struct idr_layer *p)
79{
80 unsigned long flags;
81
82 /*
83 * Depends on the return element being zeroed.
84 */
85 spin_lock_irqsave(&idp->lock, flags);
86 __move_to_free_list(idp, p);
87 spin_unlock_irqrestore(&idp->lock, flags);
88}
89
90static void idr_mark_full(struct idr_layer **pa, int id)
91{
92 struct idr_layer *p = pa[0];
93 int l = 0;
94
95 __set_bit(id & IDR_MASK, &p->bitmap);
96 /*
97 * If this layer is full mark the bit in the layer above to
98 * show that this part of the radix tree is full. This may
99 * complete the layer above and require walking up the radix
100 * tree.
101 */
102 while (p->bitmap == IDR_FULL) {
103 if (!(p = pa[++l]))
104 break;
105 id = id >> IDR_BITS;
106 __set_bit((id & IDR_MASK), &p->bitmap);
107 }
108}
109
110/**
111 * idr_pre_get - reserve resources for idr allocation
112 * @idp: idr handle
113 * @gfp_mask: memory allocation flags
114 *
115 * This function should be called prior to calling the idr_get_new* functions.
116 * It preallocates enough memory to satisfy the worst possible allocation. The
117 * caller should pass in GFP_KERNEL if possible. This of course requires that
118 * no spinning locks be held.
119 *
120 * If the system is REALLY out of memory this function returns %0,
121 * otherwise %1.
122 */
123int idr_pre_get(struct idr *idp, gfp_t gfp_mask)
124{
125 while (idp->id_free_cnt < IDR_FREE_MAX) {
126 struct idr_layer *new;
127 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
128 if (new == NULL)
129 return (0);
130 move_to_free_list(idp, new);
131 }
132 return 1;
133}
134EXPORT_SYMBOL(idr_pre_get);
135
136static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
137{
138 int n, m, sh;
139 struct idr_layer *p, *new;
140 int l, id, oid;
141 unsigned long bm;
142
143 id = *starting_id;
144 restart:
145 p = idp->top;
146 l = idp->layers;
147 pa[l--] = NULL;
148 while (1) {
149 /*
150 * We run around this while until we reach the leaf node...
151 */
152 n = (id >> (IDR_BITS*l)) & IDR_MASK;
153 bm = ~p->bitmap;
154 m = find_next_bit(&bm, IDR_SIZE, n);
155 if (m == IDR_SIZE) {
156 /* no space available go back to previous layer. */
157 l++;
158 oid = id;
159 id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
160
161 /* if already at the top layer, we need to grow */
162 if (id >= 1 << (idp->layers * IDR_BITS)) {
163 *starting_id = id;
164 return IDR_NEED_TO_GROW;
165 }
166 p = pa[l];
167 BUG_ON(!p);
168
169 /* If we need to go up one layer, continue the
170 * loop; otherwise, restart from the top.
171 */
172 sh = IDR_BITS * (l + 1);
173 if (oid >> sh == id >> sh)
174 continue;
175 else
176 goto restart;
177 }
178 if (m != n) {
179 sh = IDR_BITS*l;
180 id = ((id >> sh) ^ n ^ m) << sh;
181 }
182 if ((id >= MAX_ID_BIT) || (id < 0))
183 return IDR_NOMORE_SPACE;
184 if (l == 0)
185 break;
186 /*
187 * Create the layer below if it is missing.
188 */
189 if (!p->ary[m]) {
190 new = get_from_free_list(idp);
191 if (!new)
192 return -1;
193 new->layer = l-1;
194 rcu_assign_pointer(p->ary[m], new);
195 p->count++;
196 }
197 pa[l--] = p;
198 p = p->ary[m];
199 }
200
201 pa[l] = p;
202 return id;
203}
204
205static int idr_get_empty_slot(struct idr *idp, int starting_id,
206 struct idr_layer **pa)
207{
208 struct idr_layer *p, *new;
209 int layers, v, id;
210 unsigned long flags;
211
212 id = starting_id;
213build_up:
214 p = idp->top;
215 layers = idp->layers;
216 if (unlikely(!p)) {
217 if (!(p = get_from_free_list(idp)))
218 return -1;
219 p->layer = 0;
220 layers = 1;
221 }
222 /*
223 * Add a new layer to the top of the tree if the requested
224 * id is larger than the currently allocated space.
225 */
226 while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) {
227 layers++;
228 if (!p->count) {
229 /* special case: if the tree is currently empty,
230 * then we grow the tree by moving the top node
231 * upwards.
232 */
233 p->layer++;
234 continue;
235 }
236 if (!(new = get_from_free_list(idp))) {
237 /*
238 * The allocation failed. If we built part of
239 * the structure tear it down.
240 */
241 spin_lock_irqsave(&idp->lock, flags);
242 for (new = p; p && p != idp->top; new = p) {
243 p = p->ary[0];
244 new->ary[0] = NULL;
245 new->bitmap = new->count = 0;
246 __move_to_free_list(idp, new);
247 }
248 spin_unlock_irqrestore(&idp->lock, flags);
249 return -1;
250 }
251 new->ary[0] = p;
252 new->count = 1;
253 new->layer = layers-1;
254 if (p->bitmap == IDR_FULL)
255 __set_bit(0, &new->bitmap);
256 p = new;
257 }
258 rcu_assign_pointer(idp->top, p);
259 idp->layers = layers;
260 v = sub_alloc(idp, &id, pa);
261 if (v == IDR_NEED_TO_GROW)
262 goto build_up;
263 return(v);
264}
265
266static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id)
267{
268 struct idr_layer *pa[MAX_LEVEL];
269 int id;
270
271 id = idr_get_empty_slot(idp, starting_id, pa);
272 if (id >= 0) {
273 /*
274 * Successfully found an empty slot. Install the user
275 * pointer and mark the slot full.
276 */
277 rcu_assign_pointer(pa[0]->ary[id & IDR_MASK],
278 (struct idr_layer *)ptr);
279 pa[0]->count++;
280 idr_mark_full(pa, id);
281 }
282
283 return id;
284}
285
286/**
287 * idr_get_new_above - allocate new idr entry above or equal to a start id
288 * @idp: idr handle
289 * @ptr: pointer you want associated with the id
290 * @starting_id: id to start search at
291 * @id: pointer to the allocated handle
292 *
293 * This is the allocate id function. It should be called with any
294 * required locks.
295 *
296 * If allocation from IDR's private freelist fails, idr_get_new_above() will
297 * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill
298 * IDR's preallocation and then retry the idr_get_new_above() call.
299 *
300 * If the idr is full idr_get_new_above() will return %-ENOSPC.
301 *
302 * @id returns a value in the range @starting_id ... %0x7fffffff
303 */
304int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
305{
306 int rv;
307
308 rv = idr_get_new_above_int(idp, ptr, starting_id);
309 /*
310 * This is a cheap hack until the IDR code can be fixed to
311 * return proper error values.
312 */
313 if (rv < 0)
314 return _idr_rc_to_errno(rv);
315 *id = rv;
316 return 0;
317}
318EXPORT_SYMBOL(idr_get_new_above);
319
320/**
321 * idr_get_new - allocate new idr entry
322 * @idp: idr handle
323 * @ptr: pointer you want associated with the id
324 * @id: pointer to the allocated handle
325 *
326 * If allocation from IDR's private freelist fails, idr_get_new_above() will
327 * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill
328 * IDR's preallocation and then retry the idr_get_new_above() call.
329 *
330 * If the idr is full idr_get_new_above() will return %-ENOSPC.
331 *
332 * @id returns a value in the range %0 ... %0x7fffffff
333 */
334int idr_get_new(struct idr *idp, void *ptr, int *id)
335{
336 int rv;
337
338 rv = idr_get_new_above_int(idp, ptr, 0);
339 /*
340 * This is a cheap hack until the IDR code can be fixed to
341 * return proper error values.
342 */
343 if (rv < 0)
344 return _idr_rc_to_errno(rv);
345 *id = rv;
346 return 0;
347}
348EXPORT_SYMBOL(idr_get_new);
349
350static void idr_remove_warning(int id)
351{
352 printk(KERN_WARNING
353 "idr_remove called for id=%d which is not allocated.\n", id);
354 dump_stack();
355}
356
357static void sub_remove(struct idr *idp, int shift, int id)
358{
359 struct idr_layer *p = idp->top;
360 struct idr_layer **pa[MAX_LEVEL];
361 struct idr_layer ***paa = &pa[0];
362 struct idr_layer *to_free;
363 int n;
364
365 *paa = NULL;
366 *++paa = &idp->top;
367
368 while ((shift > 0) && p) {
369 n = (id >> shift) & IDR_MASK;
370 __clear_bit(n, &p->bitmap);
371 *++paa = &p->ary[n];
372 p = p->ary[n];
373 shift -= IDR_BITS;
374 }
375 n = id & IDR_MASK;
376 if (likely(p != NULL && test_bit(n, &p->bitmap))){
377 __clear_bit(n, &p->bitmap);
378 rcu_assign_pointer(p->ary[n], NULL);
379 to_free = NULL;
380 while(*paa && ! --((**paa)->count)){
381 if (to_free)
382 free_layer(to_free);
383 to_free = **paa;
384 **paa-- = NULL;
385 }
386 if (!*paa)
387 idp->layers = 0;
388 if (to_free)
389 free_layer(to_free);
390 } else
391 idr_remove_warning(id);
392}
393
394/**
395 * idr_remove - remove the given id and free its slot
396 * @idp: idr handle
397 * @id: unique key
398 */
399void idr_remove(struct idr *idp, int id)
400{
401 struct idr_layer *p;
402 struct idr_layer *to_free;
403
404 /* Mask off upper bits we don't use for the search. */
405 id &= MAX_ID_MASK;
406
407 sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
408 if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
409 idp->top->ary[0]) {
410 /*
411 * Single child at leftmost slot: we can shrink the tree.
412 * This level is not needed anymore since when layers are
413 * inserted, they are inserted at the top of the existing
414 * tree.
415 */
416 to_free = idp->top;
417 p = idp->top->ary[0];
418 rcu_assign_pointer(idp->top, p);
419 --idp->layers;
420 to_free->bitmap = to_free->count = 0;
421 free_layer(to_free);
422 }
423 while (idp->id_free_cnt >= IDR_FREE_MAX) {
424 p = get_from_free_list(idp);
425 /*
426 * Note: we don't call the rcu callback here, since the only
427 * layers that fall into the freelist are those that have been
428 * preallocated.
429 */
430 kmem_cache_free(idr_layer_cache, p);
431 }
432 return;
433}
434EXPORT_SYMBOL(idr_remove);
435
436/**
437 * idr_remove_all - remove all ids from the given idr tree
438 * @idp: idr handle
439 *
440 * idr_destroy() only frees up unused, cached idp_layers, but this
441 * function will remove all id mappings and leave all idp_layers
442 * unused.
443 *
444 * A typical clean-up sequence for objects stored in an idr tree will
445 * use idr_for_each() to free all objects, if necessay, then
446 * idr_remove_all() to remove all ids, and idr_destroy() to free
447 * up the cached idr_layers.
448 */
449void idr_remove_all(struct idr *idp)
450{
451 int n, id, max;
452 int bt_mask;
453 struct idr_layer *p;
454 struct idr_layer *pa[MAX_LEVEL];
455 struct idr_layer **paa = &pa[0];
456
457 n = idp->layers * IDR_BITS;
458 p = idp->top;
459 rcu_assign_pointer(idp->top, NULL);
460 max = 1 << n;
461
462 id = 0;
463 while (id < max) {
464 while (n > IDR_BITS && p) {
465 n -= IDR_BITS;
466 *paa++ = p;
467 p = p->ary[(id >> n) & IDR_MASK];
468 }
469
470 bt_mask = id;
471 id += 1 << n;
472 /* Get the highest bit that the above add changed from 0->1. */
473 while (n < fls(id ^ bt_mask)) {
474 if (p)
475 free_layer(p);
476 n += IDR_BITS;
477 p = *--paa;
478 }
479 }
480 idp->layers = 0;
481}
482EXPORT_SYMBOL(idr_remove_all);
483
484/**
485 * idr_destroy - release all cached layers within an idr tree
486 * @idp: idr handle
487 */
488void idr_destroy(struct idr *idp)
489{
490 while (idp->id_free_cnt) {
491 struct idr_layer *p = get_from_free_list(idp);
492 kmem_cache_free(idr_layer_cache, p);
493 }
494}
495EXPORT_SYMBOL(idr_destroy);
496
497/**
498 * idr_find - return pointer for given id
499 * @idp: idr handle
500 * @id: lookup key
501 *
502 * Return the pointer given the id it has been registered with. A %NULL
503 * return indicates that @id is not valid or you passed %NULL in
504 * idr_get_new().
505 *
506 * This function can be called under rcu_read_lock(), given that the leaf
507 * pointers lifetimes are correctly managed.
508 */
509void *idr_find(struct idr *idp, int id)
510{
511 int n;
512 struct idr_layer *p;
513
514 p = rcu_dereference_raw(idp->top);
515 if (!p)
516 return NULL;
517 n = (p->layer+1) * IDR_BITS;
518
519 /* Mask off upper bits we don't use for the search. */
520 id &= MAX_ID_MASK;
521
522 if (id >= (1 << n))
523 return NULL;
524 BUG_ON(n == 0);
525
526 while (n > 0 && p) {
527 n -= IDR_BITS;
528 BUG_ON(n != p->layer*IDR_BITS);
529 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
530 }
531 return((void *)p);
532}
533EXPORT_SYMBOL(idr_find);
534
535/**
536 * idr_for_each - iterate through all stored pointers
537 * @idp: idr handle
538 * @fn: function to be called for each pointer
539 * @data: data passed back to callback function
540 *
541 * Iterate over the pointers registered with the given idr. The
542 * callback function will be called for each pointer currently
543 * registered, passing the id, the pointer and the data pointer passed
544 * to this function. It is not safe to modify the idr tree while in
545 * the callback, so functions such as idr_get_new and idr_remove are
546 * not allowed.
547 *
548 * We check the return of @fn each time. If it returns anything other
549 * than %0, we break out and return that value.
550 *
551 * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
552 */
553int idr_for_each(struct idr *idp,
554 int (*fn)(int id, void *p, void *data), void *data)
555{
556 int n, id, max, error = 0;
557 struct idr_layer *p;
558 struct idr_layer *pa[MAX_LEVEL];
559 struct idr_layer **paa = &pa[0];
560
561 n = idp->layers * IDR_BITS;
562 p = rcu_dereference_raw(idp->top);
563 max = 1 << n;
564
565 id = 0;
566 while (id < max) {
567 while (n > 0 && p) {
568 n -= IDR_BITS;
569 *paa++ = p;
570 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
571 }
572
573 if (p) {
574 error = fn(id, (void *)p, data);
575 if (error)
576 break;
577 }
578
579 id += 1 << n;
580 while (n < fls(id)) {
581 n += IDR_BITS;
582 p = *--paa;
583 }
584 }
585
586 return error;
587}
588EXPORT_SYMBOL(idr_for_each);
589
590/**
591 * idr_get_next - lookup next object of id to given id.
592 * @idp: idr handle
593 * @nextidp: pointer to lookup key
594 *
595 * Returns pointer to registered object with id, which is next number to
596 * given id. After being looked up, *@nextidp will be updated for the next
597 * iteration.
598 */
599
600void *idr_get_next(struct idr *idp, int *nextidp)
601{
602 struct idr_layer *p, *pa[MAX_LEVEL];
603 struct idr_layer **paa = &pa[0];
604 int id = *nextidp;
605 int n, max;
606
607 /* find first ent */
608 n = idp->layers * IDR_BITS;
609 max = 1 << n;
610 p = rcu_dereference_raw(idp->top);
611 if (!p)
612 return NULL;
613
614 while (id < max) {
615 while (n > 0 && p) {
616 n -= IDR_BITS;
617 *paa++ = p;
618 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
619 }
620
621 if (p) {
622 *nextidp = id;
623 return p;
624 }
625
626 id += 1 << n;
627 while (n < fls(id)) {
628 n += IDR_BITS;
629 p = *--paa;
630 }
631 }
632 return NULL;
633}
634EXPORT_SYMBOL(idr_get_next);
635
636
637/**
638 * idr_replace - replace pointer for given id
639 * @idp: idr handle
640 * @ptr: pointer you want associated with the id
641 * @id: lookup key
642 *
643 * Replace the pointer registered with an id and return the old value.
644 * A %-ENOENT return indicates that @id was not found.
645 * A %-EINVAL return indicates that @id was not within valid constraints.
646 *
647 * The caller must serialize with writers.
648 */
649void *idr_replace(struct idr *idp, void *ptr, int id)
650{
651 int n;
652 struct idr_layer *p, *old_p;
653
654 p = idp->top;
655 if (!p)
656 return ERR_PTR(-EINVAL);
657
658 n = (p->layer+1) * IDR_BITS;
659
660 id &= MAX_ID_MASK;
661
662 if (id >= (1 << n))
663 return ERR_PTR(-EINVAL);
664
665 n -= IDR_BITS;
666 while ((n > 0) && p) {
667 p = p->ary[(id >> n) & IDR_MASK];
668 n -= IDR_BITS;
669 }
670
671 n = id & IDR_MASK;
672 if (unlikely(p == NULL || !test_bit(n, &p->bitmap)))
673 return ERR_PTR(-ENOENT);
674
675 old_p = p->ary[n];
676 rcu_assign_pointer(p->ary[n], ptr);
677
678 return old_p;
679}
680EXPORT_SYMBOL(idr_replace);
681
682void __init idr_init_cache(void)
683{
684 idr_layer_cache = kmem_cache_create("idr_layer_cache",
685 sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
686}
687
688/**
689 * idr_init - initialize idr handle
690 * @idp: idr handle
691 *
692 * This function is use to set up the handle (@idp) that you will pass
693 * to the rest of the functions.
694 */
695void idr_init(struct idr *idp)
696{
697 memset(idp, 0, sizeof(struct idr));
698 spin_lock_init(&idp->lock);
699}
700EXPORT_SYMBOL(idr_init);
701
702
703/**
704 * DOC: IDA description
705 * IDA - IDR based ID allocator
706 *
707 * This is id allocator without id -> pointer translation. Memory
708 * usage is much lower than full blown idr because each id only
709 * occupies a bit. ida uses a custom leaf node which contains
710 * IDA_BITMAP_BITS slots.
711 *
712 * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
713 */
714
715static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
716{
717 unsigned long flags;
718
719 if (!ida->free_bitmap) {
720 spin_lock_irqsave(&ida->idr.lock, flags);
721 if (!ida->free_bitmap) {
722 ida->free_bitmap = bitmap;
723 bitmap = NULL;
724 }
725 spin_unlock_irqrestore(&ida->idr.lock, flags);
726 }
727
728 kfree(bitmap);
729}
730
731/**
732 * ida_pre_get - reserve resources for ida allocation
733 * @ida: ida handle
734 * @gfp_mask: memory allocation flag
735 *
736 * This function should be called prior to locking and calling the
737 * following function. It preallocates enough memory to satisfy the
738 * worst possible allocation.
739 *
740 * If the system is REALLY out of memory this function returns %0,
741 * otherwise %1.
742 */
743int ida_pre_get(struct ida *ida, gfp_t gfp_mask)
744{
745 /* allocate idr_layers */
746 if (!idr_pre_get(&ida->idr, gfp_mask))
747 return 0;
748
749 /* allocate free_bitmap */
750 if (!ida->free_bitmap) {
751 struct ida_bitmap *bitmap;
752
753 bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
754 if (!bitmap)
755 return 0;
756
757 free_bitmap(ida, bitmap);
758 }
759
760 return 1;
761}
762EXPORT_SYMBOL(ida_pre_get);
763
764/**
765 * ida_get_new_above - allocate new ID above or equal to a start id
766 * @ida: ida handle
767 * @starting_id: id to start search at
768 * @p_id: pointer to the allocated handle
769 *
770 * Allocate new ID above or equal to @ida. It should be called with
771 * any required locks.
772 *
773 * If memory is required, it will return %-EAGAIN, you should unlock
774 * and go back to the ida_pre_get() call. If the ida is full, it will
775 * return %-ENOSPC.
776 *
777 * @p_id returns a value in the range @starting_id ... %0x7fffffff.
778 */
779int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
780{
781 struct idr_layer *pa[MAX_LEVEL];
782 struct ida_bitmap *bitmap;
783 unsigned long flags;
784 int idr_id = starting_id / IDA_BITMAP_BITS;
785 int offset = starting_id % IDA_BITMAP_BITS;
786 int t, id;
787
788 restart:
789 /* get vacant slot */
790 t = idr_get_empty_slot(&ida->idr, idr_id, pa);
791 if (t < 0)
792 return _idr_rc_to_errno(t);
793
794 if (t * IDA_BITMAP_BITS >= MAX_ID_BIT)
795 return -ENOSPC;
796
797 if (t != idr_id)
798 offset = 0;
799 idr_id = t;
800
801 /* if bitmap isn't there, create a new one */
802 bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
803 if (!bitmap) {
804 spin_lock_irqsave(&ida->idr.lock, flags);
805 bitmap = ida->free_bitmap;
806 ida->free_bitmap = NULL;
807 spin_unlock_irqrestore(&ida->idr.lock, flags);
808
809 if (!bitmap)
810 return -EAGAIN;
811
812 memset(bitmap, 0, sizeof(struct ida_bitmap));
813 rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
814 (void *)bitmap);
815 pa[0]->count++;
816 }
817
818 /* lookup for empty slot */
819 t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
820 if (t == IDA_BITMAP_BITS) {
821 /* no empty slot after offset, continue to the next chunk */
822 idr_id++;
823 offset = 0;
824 goto restart;
825 }
826
827 id = idr_id * IDA_BITMAP_BITS + t;
828 if (id >= MAX_ID_BIT)
829 return -ENOSPC;
830
831 __set_bit(t, bitmap->bitmap);
832 if (++bitmap->nr_busy == IDA_BITMAP_BITS)
833 idr_mark_full(pa, idr_id);
834
835 *p_id = id;
836
837 /* Each leaf node can handle nearly a thousand slots and the
838 * whole idea of ida is to have small memory foot print.
839 * Throw away extra resources one by one after each successful
840 * allocation.
841 */
842 if (ida->idr.id_free_cnt || ida->free_bitmap) {
843 struct idr_layer *p = get_from_free_list(&ida->idr);
844 if (p)
845 kmem_cache_free(idr_layer_cache, p);
846 }
847
848 return 0;
849}
850EXPORT_SYMBOL(ida_get_new_above);
851
852/**
853 * ida_get_new - allocate new ID
854 * @ida: idr handle
855 * @p_id: pointer to the allocated handle
856 *
857 * Allocate new ID. It should be called with any required locks.
858 *
859 * If memory is required, it will return %-EAGAIN, you should unlock
860 * and go back to the idr_pre_get() call. If the idr is full, it will
861 * return %-ENOSPC.
862 *
863 * @id returns a value in the range %0 ... %0x7fffffff.
864 */
865int ida_get_new(struct ida *ida, int *p_id)
866{
867 return ida_get_new_above(ida, 0, p_id);
868}
869EXPORT_SYMBOL(ida_get_new);
870
871/**
872 * ida_remove - remove the given ID
873 * @ida: ida handle
874 * @id: ID to free
875 */
876void ida_remove(struct ida *ida, int id)
877{
878 struct idr_layer *p = ida->idr.top;
879 int shift = (ida->idr.layers - 1) * IDR_BITS;
880 int idr_id = id / IDA_BITMAP_BITS;
881 int offset = id % IDA_BITMAP_BITS;
882 int n;
883 struct ida_bitmap *bitmap;
884
885 /* clear full bits while looking up the leaf idr_layer */
886 while ((shift > 0) && p) {
887 n = (idr_id >> shift) & IDR_MASK;
888 __clear_bit(n, &p->bitmap);
889 p = p->ary[n];
890 shift -= IDR_BITS;
891 }
892
893 if (p == NULL)
894 goto err;
895
896 n = idr_id & IDR_MASK;
897 __clear_bit(n, &p->bitmap);
898
899 bitmap = (void *)p->ary[n];
900 if (!test_bit(offset, bitmap->bitmap))
901 goto err;
902
903 /* update bitmap and remove it if empty */
904 __clear_bit(offset, bitmap->bitmap);
905 if (--bitmap->nr_busy == 0) {
906 __set_bit(n, &p->bitmap); /* to please idr_remove() */
907 idr_remove(&ida->idr, idr_id);
908 free_bitmap(ida, bitmap);
909 }
910
911 return;
912
913 err:
914 printk(KERN_WARNING
915 "ida_remove called for id=%d which is not allocated.\n", id);
916}
917EXPORT_SYMBOL(ida_remove);
918
919/**
920 * ida_destroy - release all cached layers within an ida tree
921 * @ida: ida handle
922 */
923void ida_destroy(struct ida *ida)
924{
925 idr_destroy(&ida->idr);
926 kfree(ida->free_bitmap);
927}
928EXPORT_SYMBOL(ida_destroy);
929
930/**
931 * ida_simple_get - get a new id.
932 * @ida: the (initialized) ida.
933 * @start: the minimum id (inclusive, < 0x8000000)
934 * @end: the maximum id (exclusive, < 0x8000000 or 0)
935 * @gfp_mask: memory allocation flags
936 *
937 * Allocates an id in the range start <= id < end, or returns -ENOSPC.
938 * On memory allocation failure, returns -ENOMEM.
939 *
940 * Use ida_simple_remove() to get rid of an id.
941 */
942int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
943 gfp_t gfp_mask)
944{
945 int ret, id;
946 unsigned int max;
947
948 BUG_ON((int)start < 0);
949 BUG_ON((int)end < 0);
950
951 if (end == 0)
952 max = 0x80000000;
953 else {
954 BUG_ON(end < start);
955 max = end - 1;
956 }
957
958again:
959 if (!ida_pre_get(ida, gfp_mask))
960 return -ENOMEM;
961
962 spin_lock(&simple_ida_lock);
963 ret = ida_get_new_above(ida, start, &id);
964 if (!ret) {
965 if (id > max) {
966 ida_remove(ida, id);
967 ret = -ENOSPC;
968 } else {
969 ret = id;
970 }
971 }
972 spin_unlock(&simple_ida_lock);
973
974 if (unlikely(ret == -EAGAIN))
975 goto again;
976
977 return ret;
978}
979EXPORT_SYMBOL(ida_simple_get);
980
981/**
982 * ida_simple_remove - remove an allocated id.
983 * @ida: the (initialized) ida.
984 * @id: the id returned by ida_simple_get.
985 */
986void ida_simple_remove(struct ida *ida, unsigned int id)
987{
988 BUG_ON((int)id < 0);
989 spin_lock(&simple_ida_lock);
990 ida_remove(ida, id);
991 spin_unlock(&simple_ida_lock);
992}
993EXPORT_SYMBOL(ida_simple_remove);
994
995/**
996 * ida_init - initialize ida handle
997 * @ida: ida handle
998 *
999 * This function is use to set up the handle (@ida) that you will pass
1000 * to the rest of the functions.
1001 */
1002void ida_init(struct ida *ida)
1003{
1004 memset(ida, 0, sizeof(struct ida));
1005 idr_init(&ida->idr);
1006
1007}
1008EXPORT_SYMBOL(ida_init);
1/*
2 * 2002-10-18 written by Jim Houston jim.houston@ccur.com
3 * Copyright (C) 2002 by Concurrent Computer Corporation
4 * Distributed under the GNU GPL license version 2.
5 *
6 * Modified by George Anzinger to reuse immediately and to use
7 * find bit instructions. Also removed _irq on spinlocks.
8 *
9 * Modified by Nadia Derbey to make it RCU safe.
10 *
11 * Small id to pointer translation service.
12 *
13 * It uses a radix tree like structure as a sparse array indexed
14 * by the id to obtain the pointer. The bitmap makes allocating
15 * a new id quick.
16 *
17 * You call it to allocate an id (an int) an associate with that id a
18 * pointer or what ever, we treat it as a (void *). You can pass this
19 * id to a user for him to pass back at a later time. You then pass
20 * that id to this code and it returns your pointer.
21
22 * You can release ids at any time. When all ids are released, most of
23 * the memory is returned (we keep MAX_IDR_FREE) in a local pool so we
24 * don't need to go to the memory "store" during an id allocate, just
25 * so you don't need to be too concerned about locking and conflicts
26 * with the slab allocator.
27 */
28
29#ifndef TEST // to test in user space...
30#include <linux/slab.h>
31#include <linux/init.h>
32#include <linux/export.h>
33#endif
34#include <linux/err.h>
35#include <linux/string.h>
36#include <linux/idr.h>
37#include <linux/spinlock.h>
38#include <linux/percpu.h>
39#include <linux/hardirq.h>
40
41#define MAX_IDR_SHIFT (sizeof(int) * 8 - 1)
42#define MAX_IDR_BIT (1U << MAX_IDR_SHIFT)
43
44/* Leave the possibility of an incomplete final layer */
45#define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS)
46
47/* Number of id_layer structs to leave in free list */
48#define MAX_IDR_FREE (MAX_IDR_LEVEL * 2)
49
50static struct kmem_cache *idr_layer_cache;
51static DEFINE_PER_CPU(struct idr_layer *, idr_preload_head);
52static DEFINE_PER_CPU(int, idr_preload_cnt);
53static DEFINE_SPINLOCK(simple_ida_lock);
54
55/* the maximum ID which can be allocated given idr->layers */
56static int idr_max(int layers)
57{
58 int bits = min_t(int, layers * IDR_BITS, MAX_IDR_SHIFT);
59
60 return (1 << bits) - 1;
61}
62
63/*
64 * Prefix mask for an idr_layer at @layer. For layer 0, the prefix mask is
65 * all bits except for the lower IDR_BITS. For layer 1, 2 * IDR_BITS, and
66 * so on.
67 */
68static int idr_layer_prefix_mask(int layer)
69{
70 return ~idr_max(layer + 1);
71}
72
73static struct idr_layer *get_from_free_list(struct idr *idp)
74{
75 struct idr_layer *p;
76 unsigned long flags;
77
78 spin_lock_irqsave(&idp->lock, flags);
79 if ((p = idp->id_free)) {
80 idp->id_free = p->ary[0];
81 idp->id_free_cnt--;
82 p->ary[0] = NULL;
83 }
84 spin_unlock_irqrestore(&idp->lock, flags);
85 return(p);
86}
87
88/**
89 * idr_layer_alloc - allocate a new idr_layer
90 * @gfp_mask: allocation mask
91 * @layer_idr: optional idr to allocate from
92 *
93 * If @layer_idr is %NULL, directly allocate one using @gfp_mask or fetch
94 * one from the per-cpu preload buffer. If @layer_idr is not %NULL, fetch
95 * an idr_layer from @idr->id_free.
96 *
97 * @layer_idr is to maintain backward compatibility with the old alloc
98 * interface - idr_pre_get() and idr_get_new*() - and will be removed
99 * together with per-pool preload buffer.
100 */
101static struct idr_layer *idr_layer_alloc(gfp_t gfp_mask, struct idr *layer_idr)
102{
103 struct idr_layer *new;
104
105 /* this is the old path, bypass to get_from_free_list() */
106 if (layer_idr)
107 return get_from_free_list(layer_idr);
108
109 /*
110 * Try to allocate directly from kmem_cache. We want to try this
111 * before preload buffer; otherwise, non-preloading idr_alloc()
112 * users will end up taking advantage of preloading ones. As the
113 * following is allowed to fail for preloaded cases, suppress
114 * warning this time.
115 */
116 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask | __GFP_NOWARN);
117 if (new)
118 return new;
119
120 /*
121 * Try to fetch one from the per-cpu preload buffer if in process
122 * context. See idr_preload() for details.
123 */
124 if (!in_interrupt()) {
125 preempt_disable();
126 new = __this_cpu_read(idr_preload_head);
127 if (new) {
128 __this_cpu_write(idr_preload_head, new->ary[0]);
129 __this_cpu_dec(idr_preload_cnt);
130 new->ary[0] = NULL;
131 }
132 preempt_enable();
133 if (new)
134 return new;
135 }
136
137 /*
138 * Both failed. Try kmem_cache again w/o adding __GFP_NOWARN so
139 * that memory allocation failure warning is printed as intended.
140 */
141 return kmem_cache_zalloc(idr_layer_cache, gfp_mask);
142}
143
144static void idr_layer_rcu_free(struct rcu_head *head)
145{
146 struct idr_layer *layer;
147
148 layer = container_of(head, struct idr_layer, rcu_head);
149 kmem_cache_free(idr_layer_cache, layer);
150}
151
152static inline void free_layer(struct idr *idr, struct idr_layer *p)
153{
154 if (idr->hint && idr->hint == p)
155 RCU_INIT_POINTER(idr->hint, NULL);
156 call_rcu(&p->rcu_head, idr_layer_rcu_free);
157}
158
159/* only called when idp->lock is held */
160static void __move_to_free_list(struct idr *idp, struct idr_layer *p)
161{
162 p->ary[0] = idp->id_free;
163 idp->id_free = p;
164 idp->id_free_cnt++;
165}
166
167static void move_to_free_list(struct idr *idp, struct idr_layer *p)
168{
169 unsigned long flags;
170
171 /*
172 * Depends on the return element being zeroed.
173 */
174 spin_lock_irqsave(&idp->lock, flags);
175 __move_to_free_list(idp, p);
176 spin_unlock_irqrestore(&idp->lock, flags);
177}
178
179static void idr_mark_full(struct idr_layer **pa, int id)
180{
181 struct idr_layer *p = pa[0];
182 int l = 0;
183
184 __set_bit(id & IDR_MASK, p->bitmap);
185 /*
186 * If this layer is full mark the bit in the layer above to
187 * show that this part of the radix tree is full. This may
188 * complete the layer above and require walking up the radix
189 * tree.
190 */
191 while (bitmap_full(p->bitmap, IDR_SIZE)) {
192 if (!(p = pa[++l]))
193 break;
194 id = id >> IDR_BITS;
195 __set_bit((id & IDR_MASK), p->bitmap);
196 }
197}
198
199static int __idr_pre_get(struct idr *idp, gfp_t gfp_mask)
200{
201 while (idp->id_free_cnt < MAX_IDR_FREE) {
202 struct idr_layer *new;
203 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
204 if (new == NULL)
205 return (0);
206 move_to_free_list(idp, new);
207 }
208 return 1;
209}
210
211/**
212 * sub_alloc - try to allocate an id without growing the tree depth
213 * @idp: idr handle
214 * @starting_id: id to start search at
215 * @pa: idr_layer[MAX_IDR_LEVEL] used as backtrack buffer
216 * @gfp_mask: allocation mask for idr_layer_alloc()
217 * @layer_idr: optional idr passed to idr_layer_alloc()
218 *
219 * Allocate an id in range [@starting_id, INT_MAX] from @idp without
220 * growing its depth. Returns
221 *
222 * the allocated id >= 0 if successful,
223 * -EAGAIN if the tree needs to grow for allocation to succeed,
224 * -ENOSPC if the id space is exhausted,
225 * -ENOMEM if more idr_layers need to be allocated.
226 */
227static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa,
228 gfp_t gfp_mask, struct idr *layer_idr)
229{
230 int n, m, sh;
231 struct idr_layer *p, *new;
232 int l, id, oid;
233
234 id = *starting_id;
235 restart:
236 p = idp->top;
237 l = idp->layers;
238 pa[l--] = NULL;
239 while (1) {
240 /*
241 * We run around this while until we reach the leaf node...
242 */
243 n = (id >> (IDR_BITS*l)) & IDR_MASK;
244 m = find_next_zero_bit(p->bitmap, IDR_SIZE, n);
245 if (m == IDR_SIZE) {
246 /* no space available go back to previous layer. */
247 l++;
248 oid = id;
249 id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
250
251 /* if already at the top layer, we need to grow */
252 if (id >= 1 << (idp->layers * IDR_BITS)) {
253 *starting_id = id;
254 return -EAGAIN;
255 }
256 p = pa[l];
257 BUG_ON(!p);
258
259 /* If we need to go up one layer, continue the
260 * loop; otherwise, restart from the top.
261 */
262 sh = IDR_BITS * (l + 1);
263 if (oid >> sh == id >> sh)
264 continue;
265 else
266 goto restart;
267 }
268 if (m != n) {
269 sh = IDR_BITS*l;
270 id = ((id >> sh) ^ n ^ m) << sh;
271 }
272 if ((id >= MAX_IDR_BIT) || (id < 0))
273 return -ENOSPC;
274 if (l == 0)
275 break;
276 /*
277 * Create the layer below if it is missing.
278 */
279 if (!p->ary[m]) {
280 new = idr_layer_alloc(gfp_mask, layer_idr);
281 if (!new)
282 return -ENOMEM;
283 new->layer = l-1;
284 new->prefix = id & idr_layer_prefix_mask(new->layer);
285 rcu_assign_pointer(p->ary[m], new);
286 p->count++;
287 }
288 pa[l--] = p;
289 p = p->ary[m];
290 }
291
292 pa[l] = p;
293 return id;
294}
295
296static int idr_get_empty_slot(struct idr *idp, int starting_id,
297 struct idr_layer **pa, gfp_t gfp_mask,
298 struct idr *layer_idr)
299{
300 struct idr_layer *p, *new;
301 int layers, v, id;
302 unsigned long flags;
303
304 id = starting_id;
305build_up:
306 p = idp->top;
307 layers = idp->layers;
308 if (unlikely(!p)) {
309 if (!(p = idr_layer_alloc(gfp_mask, layer_idr)))
310 return -ENOMEM;
311 p->layer = 0;
312 layers = 1;
313 }
314 /*
315 * Add a new layer to the top of the tree if the requested
316 * id is larger than the currently allocated space.
317 */
318 while (id > idr_max(layers)) {
319 layers++;
320 if (!p->count) {
321 /* special case: if the tree is currently empty,
322 * then we grow the tree by moving the top node
323 * upwards.
324 */
325 p->layer++;
326 WARN_ON_ONCE(p->prefix);
327 continue;
328 }
329 if (!(new = idr_layer_alloc(gfp_mask, layer_idr))) {
330 /*
331 * The allocation failed. If we built part of
332 * the structure tear it down.
333 */
334 spin_lock_irqsave(&idp->lock, flags);
335 for (new = p; p && p != idp->top; new = p) {
336 p = p->ary[0];
337 new->ary[0] = NULL;
338 new->count = 0;
339 bitmap_clear(new->bitmap, 0, IDR_SIZE);
340 __move_to_free_list(idp, new);
341 }
342 spin_unlock_irqrestore(&idp->lock, flags);
343 return -ENOMEM;
344 }
345 new->ary[0] = p;
346 new->count = 1;
347 new->layer = layers-1;
348 new->prefix = id & idr_layer_prefix_mask(new->layer);
349 if (bitmap_full(p->bitmap, IDR_SIZE))
350 __set_bit(0, new->bitmap);
351 p = new;
352 }
353 rcu_assign_pointer(idp->top, p);
354 idp->layers = layers;
355 v = sub_alloc(idp, &id, pa, gfp_mask, layer_idr);
356 if (v == -EAGAIN)
357 goto build_up;
358 return(v);
359}
360
361/*
362 * @id and @pa are from a successful allocation from idr_get_empty_slot().
363 * Install the user pointer @ptr and mark the slot full.
364 */
365static void idr_fill_slot(struct idr *idr, void *ptr, int id,
366 struct idr_layer **pa)
367{
368 /* update hint used for lookup, cleared from free_layer() */
369 rcu_assign_pointer(idr->hint, pa[0]);
370
371 rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], (struct idr_layer *)ptr);
372 pa[0]->count++;
373 idr_mark_full(pa, id);
374}
375
376
377/**
378 * idr_preload - preload for idr_alloc()
379 * @gfp_mask: allocation mask to use for preloading
380 *
381 * Preload per-cpu layer buffer for idr_alloc(). Can only be used from
382 * process context and each idr_preload() invocation should be matched with
383 * idr_preload_end(). Note that preemption is disabled while preloaded.
384 *
385 * The first idr_alloc() in the preloaded section can be treated as if it
386 * were invoked with @gfp_mask used for preloading. This allows using more
387 * permissive allocation masks for idrs protected by spinlocks.
388 *
389 * For example, if idr_alloc() below fails, the failure can be treated as
390 * if idr_alloc() were called with GFP_KERNEL rather than GFP_NOWAIT.
391 *
392 * idr_preload(GFP_KERNEL);
393 * spin_lock(lock);
394 *
395 * id = idr_alloc(idr, ptr, start, end, GFP_NOWAIT);
396 *
397 * spin_unlock(lock);
398 * idr_preload_end();
399 * if (id < 0)
400 * error;
401 */
402void idr_preload(gfp_t gfp_mask)
403{
404 /*
405 * Consuming preload buffer from non-process context breaks preload
406 * allocation guarantee. Disallow usage from those contexts.
407 */
408 WARN_ON_ONCE(in_interrupt());
409 might_sleep_if(gfp_mask & __GFP_WAIT);
410
411 preempt_disable();
412
413 /*
414 * idr_alloc() is likely to succeed w/o full idr_layer buffer and
415 * return value from idr_alloc() needs to be checked for failure
416 * anyway. Silently give up if allocation fails. The caller can
417 * treat failures from idr_alloc() as if idr_alloc() were called
418 * with @gfp_mask which should be enough.
419 */
420 while (__this_cpu_read(idr_preload_cnt) < MAX_IDR_FREE) {
421 struct idr_layer *new;
422
423 preempt_enable();
424 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
425 preempt_disable();
426 if (!new)
427 break;
428
429 /* link the new one to per-cpu preload list */
430 new->ary[0] = __this_cpu_read(idr_preload_head);
431 __this_cpu_write(idr_preload_head, new);
432 __this_cpu_inc(idr_preload_cnt);
433 }
434}
435EXPORT_SYMBOL(idr_preload);
436
437/**
438 * idr_alloc - allocate new idr entry
439 * @idr: the (initialized) idr
440 * @ptr: pointer to be associated with the new id
441 * @start: the minimum id (inclusive)
442 * @end: the maximum id (exclusive, <= 0 for max)
443 * @gfp_mask: memory allocation flags
444 *
445 * Allocate an id in [start, end) and associate it with @ptr. If no ID is
446 * available in the specified range, returns -ENOSPC. On memory allocation
447 * failure, returns -ENOMEM.
448 *
449 * Note that @end is treated as max when <= 0. This is to always allow
450 * using @start + N as @end as long as N is inside integer range.
451 *
452 * The user is responsible for exclusively synchronizing all operations
453 * which may modify @idr. However, read-only accesses such as idr_find()
454 * or iteration can be performed under RCU read lock provided the user
455 * destroys @ptr in RCU-safe way after removal from idr.
456 */
457int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask)
458{
459 int max = end > 0 ? end - 1 : INT_MAX; /* inclusive upper limit */
460 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
461 int id;
462
463 might_sleep_if(gfp_mask & __GFP_WAIT);
464
465 /* sanity checks */
466 if (WARN_ON_ONCE(start < 0))
467 return -EINVAL;
468 if (unlikely(max < start))
469 return -ENOSPC;
470
471 /* allocate id */
472 id = idr_get_empty_slot(idr, start, pa, gfp_mask, NULL);
473 if (unlikely(id < 0))
474 return id;
475 if (unlikely(id > max))
476 return -ENOSPC;
477
478 idr_fill_slot(idr, ptr, id, pa);
479 return id;
480}
481EXPORT_SYMBOL_GPL(idr_alloc);
482
483/**
484 * idr_alloc_cyclic - allocate new idr entry in a cyclical fashion
485 * @idr: the (initialized) idr
486 * @ptr: pointer to be associated with the new id
487 * @start: the minimum id (inclusive)
488 * @end: the maximum id (exclusive, <= 0 for max)
489 * @gfp_mask: memory allocation flags
490 *
491 * Essentially the same as idr_alloc, but prefers to allocate progressively
492 * higher ids if it can. If the "cur" counter wraps, then it will start again
493 * at the "start" end of the range and allocate one that has already been used.
494 */
495int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end,
496 gfp_t gfp_mask)
497{
498 int id;
499
500 id = idr_alloc(idr, ptr, max(start, idr->cur), end, gfp_mask);
501 if (id == -ENOSPC)
502 id = idr_alloc(idr, ptr, start, end, gfp_mask);
503
504 if (likely(id >= 0))
505 idr->cur = id + 1;
506 return id;
507}
508EXPORT_SYMBOL(idr_alloc_cyclic);
509
510static void idr_remove_warning(int id)
511{
512 WARN(1, "idr_remove called for id=%d which is not allocated.\n", id);
513}
514
515static void sub_remove(struct idr *idp, int shift, int id)
516{
517 struct idr_layer *p = idp->top;
518 struct idr_layer **pa[MAX_IDR_LEVEL + 1];
519 struct idr_layer ***paa = &pa[0];
520 struct idr_layer *to_free;
521 int n;
522
523 *paa = NULL;
524 *++paa = &idp->top;
525
526 while ((shift > 0) && p) {
527 n = (id >> shift) & IDR_MASK;
528 __clear_bit(n, p->bitmap);
529 *++paa = &p->ary[n];
530 p = p->ary[n];
531 shift -= IDR_BITS;
532 }
533 n = id & IDR_MASK;
534 if (likely(p != NULL && test_bit(n, p->bitmap))) {
535 __clear_bit(n, p->bitmap);
536 RCU_INIT_POINTER(p->ary[n], NULL);
537 to_free = NULL;
538 while(*paa && ! --((**paa)->count)){
539 if (to_free)
540 free_layer(idp, to_free);
541 to_free = **paa;
542 **paa-- = NULL;
543 }
544 if (!*paa)
545 idp->layers = 0;
546 if (to_free)
547 free_layer(idp, to_free);
548 } else
549 idr_remove_warning(id);
550}
551
552/**
553 * idr_remove - remove the given id and free its slot
554 * @idp: idr handle
555 * @id: unique key
556 */
557void idr_remove(struct idr *idp, int id)
558{
559 struct idr_layer *p;
560 struct idr_layer *to_free;
561
562 if (id < 0)
563 return;
564
565 sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
566 if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
567 idp->top->ary[0]) {
568 /*
569 * Single child at leftmost slot: we can shrink the tree.
570 * This level is not needed anymore since when layers are
571 * inserted, they are inserted at the top of the existing
572 * tree.
573 */
574 to_free = idp->top;
575 p = idp->top->ary[0];
576 rcu_assign_pointer(idp->top, p);
577 --idp->layers;
578 to_free->count = 0;
579 bitmap_clear(to_free->bitmap, 0, IDR_SIZE);
580 free_layer(idp, to_free);
581 }
582 while (idp->id_free_cnt >= MAX_IDR_FREE) {
583 p = get_from_free_list(idp);
584 /*
585 * Note: we don't call the rcu callback here, since the only
586 * layers that fall into the freelist are those that have been
587 * preallocated.
588 */
589 kmem_cache_free(idr_layer_cache, p);
590 }
591 return;
592}
593EXPORT_SYMBOL(idr_remove);
594
595static void __idr_remove_all(struct idr *idp)
596{
597 int n, id, max;
598 int bt_mask;
599 struct idr_layer *p;
600 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
601 struct idr_layer **paa = &pa[0];
602
603 n = idp->layers * IDR_BITS;
604 p = idp->top;
605 RCU_INIT_POINTER(idp->top, NULL);
606 max = idr_max(idp->layers);
607
608 id = 0;
609 while (id >= 0 && id <= max) {
610 while (n > IDR_BITS && p) {
611 n -= IDR_BITS;
612 *paa++ = p;
613 p = p->ary[(id >> n) & IDR_MASK];
614 }
615
616 bt_mask = id;
617 id += 1 << n;
618 /* Get the highest bit that the above add changed from 0->1. */
619 while (n < fls(id ^ bt_mask)) {
620 if (p)
621 free_layer(idp, p);
622 n += IDR_BITS;
623 p = *--paa;
624 }
625 }
626 idp->layers = 0;
627}
628
629/**
630 * idr_destroy - release all cached layers within an idr tree
631 * @idp: idr handle
632 *
633 * Free all id mappings and all idp_layers. After this function, @idp is
634 * completely unused and can be freed / recycled. The caller is
635 * responsible for ensuring that no one else accesses @idp during or after
636 * idr_destroy().
637 *
638 * A typical clean-up sequence for objects stored in an idr tree will use
639 * idr_for_each() to free all objects, if necessay, then idr_destroy() to
640 * free up the id mappings and cached idr_layers.
641 */
642void idr_destroy(struct idr *idp)
643{
644 __idr_remove_all(idp);
645
646 while (idp->id_free_cnt) {
647 struct idr_layer *p = get_from_free_list(idp);
648 kmem_cache_free(idr_layer_cache, p);
649 }
650}
651EXPORT_SYMBOL(idr_destroy);
652
653void *idr_find_slowpath(struct idr *idp, int id)
654{
655 int n;
656 struct idr_layer *p;
657
658 if (id < 0)
659 return NULL;
660
661 p = rcu_dereference_raw(idp->top);
662 if (!p)
663 return NULL;
664 n = (p->layer+1) * IDR_BITS;
665
666 if (id > idr_max(p->layer + 1))
667 return NULL;
668 BUG_ON(n == 0);
669
670 while (n > 0 && p) {
671 n -= IDR_BITS;
672 BUG_ON(n != p->layer*IDR_BITS);
673 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
674 }
675 return((void *)p);
676}
677EXPORT_SYMBOL(idr_find_slowpath);
678
679/**
680 * idr_for_each - iterate through all stored pointers
681 * @idp: idr handle
682 * @fn: function to be called for each pointer
683 * @data: data passed back to callback function
684 *
685 * Iterate over the pointers registered with the given idr. The
686 * callback function will be called for each pointer currently
687 * registered, passing the id, the pointer and the data pointer passed
688 * to this function. It is not safe to modify the idr tree while in
689 * the callback, so functions such as idr_get_new and idr_remove are
690 * not allowed.
691 *
692 * We check the return of @fn each time. If it returns anything other
693 * than %0, we break out and return that value.
694 *
695 * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
696 */
697int idr_for_each(struct idr *idp,
698 int (*fn)(int id, void *p, void *data), void *data)
699{
700 int n, id, max, error = 0;
701 struct idr_layer *p;
702 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
703 struct idr_layer **paa = &pa[0];
704
705 n = idp->layers * IDR_BITS;
706 p = rcu_dereference_raw(idp->top);
707 max = idr_max(idp->layers);
708
709 id = 0;
710 while (id >= 0 && id <= max) {
711 while (n > 0 && p) {
712 n -= IDR_BITS;
713 *paa++ = p;
714 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
715 }
716
717 if (p) {
718 error = fn(id, (void *)p, data);
719 if (error)
720 break;
721 }
722
723 id += 1 << n;
724 while (n < fls(id)) {
725 n += IDR_BITS;
726 p = *--paa;
727 }
728 }
729
730 return error;
731}
732EXPORT_SYMBOL(idr_for_each);
733
734/**
735 * idr_get_next - lookup next object of id to given id.
736 * @idp: idr handle
737 * @nextidp: pointer to lookup key
738 *
739 * Returns pointer to registered object with id, which is next number to
740 * given id. After being looked up, *@nextidp will be updated for the next
741 * iteration.
742 *
743 * This function can be called under rcu_read_lock(), given that the leaf
744 * pointers lifetimes are correctly managed.
745 */
746void *idr_get_next(struct idr *idp, int *nextidp)
747{
748 struct idr_layer *p, *pa[MAX_IDR_LEVEL + 1];
749 struct idr_layer **paa = &pa[0];
750 int id = *nextidp;
751 int n, max;
752
753 /* find first ent */
754 p = rcu_dereference_raw(idp->top);
755 if (!p)
756 return NULL;
757 n = (p->layer + 1) * IDR_BITS;
758 max = idr_max(p->layer + 1);
759
760 while (id >= 0 && id <= max) {
761 while (n > 0 && p) {
762 n -= IDR_BITS;
763 *paa++ = p;
764 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
765 }
766
767 if (p) {
768 *nextidp = id;
769 return p;
770 }
771
772 /*
773 * Proceed to the next layer at the current level. Unlike
774 * idr_for_each(), @id isn't guaranteed to be aligned to
775 * layer boundary at this point and adding 1 << n may
776 * incorrectly skip IDs. Make sure we jump to the
777 * beginning of the next layer using round_up().
778 */
779 id = round_up(id + 1, 1 << n);
780 while (n < fls(id)) {
781 n += IDR_BITS;
782 p = *--paa;
783 }
784 }
785 return NULL;
786}
787EXPORT_SYMBOL(idr_get_next);
788
789
790/**
791 * idr_replace - replace pointer for given id
792 * @idp: idr handle
793 * @ptr: pointer you want associated with the id
794 * @id: lookup key
795 *
796 * Replace the pointer registered with an id and return the old value.
797 * A %-ENOENT return indicates that @id was not found.
798 * A %-EINVAL return indicates that @id was not within valid constraints.
799 *
800 * The caller must serialize with writers.
801 */
802void *idr_replace(struct idr *idp, void *ptr, int id)
803{
804 int n;
805 struct idr_layer *p, *old_p;
806
807 if (id < 0)
808 return ERR_PTR(-EINVAL);
809
810 p = idp->top;
811 if (!p)
812 return ERR_PTR(-EINVAL);
813
814 n = (p->layer+1) * IDR_BITS;
815
816 if (id >= (1 << n))
817 return ERR_PTR(-EINVAL);
818
819 n -= IDR_BITS;
820 while ((n > 0) && p) {
821 p = p->ary[(id >> n) & IDR_MASK];
822 n -= IDR_BITS;
823 }
824
825 n = id & IDR_MASK;
826 if (unlikely(p == NULL || !test_bit(n, p->bitmap)))
827 return ERR_PTR(-ENOENT);
828
829 old_p = p->ary[n];
830 rcu_assign_pointer(p->ary[n], ptr);
831
832 return old_p;
833}
834EXPORT_SYMBOL(idr_replace);
835
836void __init idr_init_cache(void)
837{
838 idr_layer_cache = kmem_cache_create("idr_layer_cache",
839 sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
840}
841
842/**
843 * idr_init - initialize idr handle
844 * @idp: idr handle
845 *
846 * This function is use to set up the handle (@idp) that you will pass
847 * to the rest of the functions.
848 */
849void idr_init(struct idr *idp)
850{
851 memset(idp, 0, sizeof(struct idr));
852 spin_lock_init(&idp->lock);
853}
854EXPORT_SYMBOL(idr_init);
855
856static int idr_has_entry(int id, void *p, void *data)
857{
858 return 1;
859}
860
861bool idr_is_empty(struct idr *idp)
862{
863 return !idr_for_each(idp, idr_has_entry, NULL);
864}
865EXPORT_SYMBOL(idr_is_empty);
866
867/**
868 * DOC: IDA description
869 * IDA - IDR based ID allocator
870 *
871 * This is id allocator without id -> pointer translation. Memory
872 * usage is much lower than full blown idr because each id only
873 * occupies a bit. ida uses a custom leaf node which contains
874 * IDA_BITMAP_BITS slots.
875 *
876 * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
877 */
878
879static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
880{
881 unsigned long flags;
882
883 if (!ida->free_bitmap) {
884 spin_lock_irqsave(&ida->idr.lock, flags);
885 if (!ida->free_bitmap) {
886 ida->free_bitmap = bitmap;
887 bitmap = NULL;
888 }
889 spin_unlock_irqrestore(&ida->idr.lock, flags);
890 }
891
892 kfree(bitmap);
893}
894
895/**
896 * ida_pre_get - reserve resources for ida allocation
897 * @ida: ida handle
898 * @gfp_mask: memory allocation flag
899 *
900 * This function should be called prior to locking and calling the
901 * following function. It preallocates enough memory to satisfy the
902 * worst possible allocation.
903 *
904 * If the system is REALLY out of memory this function returns %0,
905 * otherwise %1.
906 */
907int ida_pre_get(struct ida *ida, gfp_t gfp_mask)
908{
909 /* allocate idr_layers */
910 if (!__idr_pre_get(&ida->idr, gfp_mask))
911 return 0;
912
913 /* allocate free_bitmap */
914 if (!ida->free_bitmap) {
915 struct ida_bitmap *bitmap;
916
917 bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
918 if (!bitmap)
919 return 0;
920
921 free_bitmap(ida, bitmap);
922 }
923
924 return 1;
925}
926EXPORT_SYMBOL(ida_pre_get);
927
928/**
929 * ida_get_new_above - allocate new ID above or equal to a start id
930 * @ida: ida handle
931 * @starting_id: id to start search at
932 * @p_id: pointer to the allocated handle
933 *
934 * Allocate new ID above or equal to @starting_id. It should be called
935 * with any required locks.
936 *
937 * If memory is required, it will return %-EAGAIN, you should unlock
938 * and go back to the ida_pre_get() call. If the ida is full, it will
939 * return %-ENOSPC.
940 *
941 * @p_id returns a value in the range @starting_id ... %0x7fffffff.
942 */
943int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
944{
945 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
946 struct ida_bitmap *bitmap;
947 unsigned long flags;
948 int idr_id = starting_id / IDA_BITMAP_BITS;
949 int offset = starting_id % IDA_BITMAP_BITS;
950 int t, id;
951
952 restart:
953 /* get vacant slot */
954 t = idr_get_empty_slot(&ida->idr, idr_id, pa, 0, &ida->idr);
955 if (t < 0)
956 return t == -ENOMEM ? -EAGAIN : t;
957
958 if (t * IDA_BITMAP_BITS >= MAX_IDR_BIT)
959 return -ENOSPC;
960
961 if (t != idr_id)
962 offset = 0;
963 idr_id = t;
964
965 /* if bitmap isn't there, create a new one */
966 bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
967 if (!bitmap) {
968 spin_lock_irqsave(&ida->idr.lock, flags);
969 bitmap = ida->free_bitmap;
970 ida->free_bitmap = NULL;
971 spin_unlock_irqrestore(&ida->idr.lock, flags);
972
973 if (!bitmap)
974 return -EAGAIN;
975
976 memset(bitmap, 0, sizeof(struct ida_bitmap));
977 rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
978 (void *)bitmap);
979 pa[0]->count++;
980 }
981
982 /* lookup for empty slot */
983 t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
984 if (t == IDA_BITMAP_BITS) {
985 /* no empty slot after offset, continue to the next chunk */
986 idr_id++;
987 offset = 0;
988 goto restart;
989 }
990
991 id = idr_id * IDA_BITMAP_BITS + t;
992 if (id >= MAX_IDR_BIT)
993 return -ENOSPC;
994
995 __set_bit(t, bitmap->bitmap);
996 if (++bitmap->nr_busy == IDA_BITMAP_BITS)
997 idr_mark_full(pa, idr_id);
998
999 *p_id = id;
1000
1001 /* Each leaf node can handle nearly a thousand slots and the
1002 * whole idea of ida is to have small memory foot print.
1003 * Throw away extra resources one by one after each successful
1004 * allocation.
1005 */
1006 if (ida->idr.id_free_cnt || ida->free_bitmap) {
1007 struct idr_layer *p = get_from_free_list(&ida->idr);
1008 if (p)
1009 kmem_cache_free(idr_layer_cache, p);
1010 }
1011
1012 return 0;
1013}
1014EXPORT_SYMBOL(ida_get_new_above);
1015
1016/**
1017 * ida_remove - remove the given ID
1018 * @ida: ida handle
1019 * @id: ID to free
1020 */
1021void ida_remove(struct ida *ida, int id)
1022{
1023 struct idr_layer *p = ida->idr.top;
1024 int shift = (ida->idr.layers - 1) * IDR_BITS;
1025 int idr_id = id / IDA_BITMAP_BITS;
1026 int offset = id % IDA_BITMAP_BITS;
1027 int n;
1028 struct ida_bitmap *bitmap;
1029
1030 /* clear full bits while looking up the leaf idr_layer */
1031 while ((shift > 0) && p) {
1032 n = (idr_id >> shift) & IDR_MASK;
1033 __clear_bit(n, p->bitmap);
1034 p = p->ary[n];
1035 shift -= IDR_BITS;
1036 }
1037
1038 if (p == NULL)
1039 goto err;
1040
1041 n = idr_id & IDR_MASK;
1042 __clear_bit(n, p->bitmap);
1043
1044 bitmap = (void *)p->ary[n];
1045 if (!test_bit(offset, bitmap->bitmap))
1046 goto err;
1047
1048 /* update bitmap and remove it if empty */
1049 __clear_bit(offset, bitmap->bitmap);
1050 if (--bitmap->nr_busy == 0) {
1051 __set_bit(n, p->bitmap); /* to please idr_remove() */
1052 idr_remove(&ida->idr, idr_id);
1053 free_bitmap(ida, bitmap);
1054 }
1055
1056 return;
1057
1058 err:
1059 WARN(1, "ida_remove called for id=%d which is not allocated.\n", id);
1060}
1061EXPORT_SYMBOL(ida_remove);
1062
1063/**
1064 * ida_destroy - release all cached layers within an ida tree
1065 * @ida: ida handle
1066 */
1067void ida_destroy(struct ida *ida)
1068{
1069 idr_destroy(&ida->idr);
1070 kfree(ida->free_bitmap);
1071}
1072EXPORT_SYMBOL(ida_destroy);
1073
1074/**
1075 * ida_simple_get - get a new id.
1076 * @ida: the (initialized) ida.
1077 * @start: the minimum id (inclusive, < 0x8000000)
1078 * @end: the maximum id (exclusive, < 0x8000000 or 0)
1079 * @gfp_mask: memory allocation flags
1080 *
1081 * Allocates an id in the range start <= id < end, or returns -ENOSPC.
1082 * On memory allocation failure, returns -ENOMEM.
1083 *
1084 * Use ida_simple_remove() to get rid of an id.
1085 */
1086int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
1087 gfp_t gfp_mask)
1088{
1089 int ret, id;
1090 unsigned int max;
1091 unsigned long flags;
1092
1093 BUG_ON((int)start < 0);
1094 BUG_ON((int)end < 0);
1095
1096 if (end == 0)
1097 max = 0x80000000;
1098 else {
1099 BUG_ON(end < start);
1100 max = end - 1;
1101 }
1102
1103again:
1104 if (!ida_pre_get(ida, gfp_mask))
1105 return -ENOMEM;
1106
1107 spin_lock_irqsave(&simple_ida_lock, flags);
1108 ret = ida_get_new_above(ida, start, &id);
1109 if (!ret) {
1110 if (id > max) {
1111 ida_remove(ida, id);
1112 ret = -ENOSPC;
1113 } else {
1114 ret = id;
1115 }
1116 }
1117 spin_unlock_irqrestore(&simple_ida_lock, flags);
1118
1119 if (unlikely(ret == -EAGAIN))
1120 goto again;
1121
1122 return ret;
1123}
1124EXPORT_SYMBOL(ida_simple_get);
1125
1126/**
1127 * ida_simple_remove - remove an allocated id.
1128 * @ida: the (initialized) ida.
1129 * @id: the id returned by ida_simple_get.
1130 */
1131void ida_simple_remove(struct ida *ida, unsigned int id)
1132{
1133 unsigned long flags;
1134
1135 BUG_ON((int)id < 0);
1136 spin_lock_irqsave(&simple_ida_lock, flags);
1137 ida_remove(ida, id);
1138 spin_unlock_irqrestore(&simple_ida_lock, flags);
1139}
1140EXPORT_SYMBOL(ida_simple_remove);
1141
1142/**
1143 * ida_init - initialize ida handle
1144 * @ida: ida handle
1145 *
1146 * This function is use to set up the handle (@ida) that you will pass
1147 * to the rest of the functions.
1148 */
1149void ida_init(struct ida *ida)
1150{
1151 memset(ida, 0, sizeof(struct ida));
1152 idr_init(&ida->idr);
1153
1154}
1155EXPORT_SYMBOL(ida_init);