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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#include <linux/bitmap.h>
2#include <linux/bug.h>
3#include <linux/export.h>
4#include <linux/idr.h>
5#include <linux/slab.h>
6#include <linux/spinlock.h>
7
8DEFINE_PER_CPU(struct ida_bitmap *, ida_bitmap);
9static DEFINE_SPINLOCK(simple_ida_lock);
10
11/**
12 * idr_alloc_u32() - Allocate an ID.
13 * @idr: IDR handle.
14 * @ptr: Pointer to be associated with the new ID.
15 * @nextid: Pointer to an ID.
16 * @max: The maximum ID to allocate (inclusive).
17 * @gfp: Memory allocation flags.
18 *
19 * Allocates an unused ID in the range specified by @nextid and @max.
20 * Note that @max is inclusive whereas the @end parameter to idr_alloc()
21 * is exclusive. The new ID is assigned to @nextid before the pointer
22 * is inserted into the IDR, so if @nextid points into the object pointed
23 * to by @ptr, a concurrent lookup will not find an uninitialised ID.
24 *
25 * The caller should provide their own locking to ensure that two
26 * concurrent modifications to the IDR are not possible. Read-only
27 * accesses to the IDR may be done under the RCU read lock or may
28 * exclude simultaneous writers.
29 *
30 * Return: 0 if an ID was allocated, -ENOMEM if memory allocation failed,
31 * or -ENOSPC if no free IDs could be found. If an error occurred,
32 * @nextid is unchanged.
33 */
34int idr_alloc_u32(struct idr *idr, void *ptr, u32 *nextid,
35 unsigned long max, gfp_t gfp)
36{
37 struct radix_tree_iter iter;
38 void __rcu **slot;
39 unsigned int base = idr->idr_base;
40 unsigned int id = *nextid;
41
42 if (WARN_ON_ONCE(radix_tree_is_internal_node(ptr)))
43 return -EINVAL;
44 if (WARN_ON_ONCE(!(idr->idr_rt.gfp_mask & ROOT_IS_IDR)))
45 idr->idr_rt.gfp_mask |= IDR_RT_MARKER;
46
47 id = (id < base) ? 0 : id - base;
48 radix_tree_iter_init(&iter, id);
49 slot = idr_get_free(&idr->idr_rt, &iter, gfp, max - base);
50 if (IS_ERR(slot))
51 return PTR_ERR(slot);
52
53 *nextid = iter.index + base;
54 /* there is a memory barrier inside radix_tree_iter_replace() */
55 radix_tree_iter_replace(&idr->idr_rt, &iter, slot, ptr);
56 radix_tree_iter_tag_clear(&idr->idr_rt, &iter, IDR_FREE);
57
58 return 0;
59}
60EXPORT_SYMBOL_GPL(idr_alloc_u32);
61
62/**
63 * idr_alloc() - Allocate an ID.
64 * @idr: IDR handle.
65 * @ptr: Pointer to be associated with the new ID.
66 * @start: The minimum ID (inclusive).
67 * @end: The maximum ID (exclusive).
68 * @gfp: Memory allocation flags.
69 *
70 * Allocates an unused ID in the range specified by @start and @end. If
71 * @end is <= 0, it is treated as one larger than %INT_MAX. This allows
72 * callers to use @start + N as @end as long as N is within integer range.
73 *
74 * The caller should provide their own locking to ensure that two
75 * concurrent modifications to the IDR are not possible. Read-only
76 * accesses to the IDR may be done under the RCU read lock or may
77 * exclude simultaneous writers.
78 *
79 * Return: The newly allocated ID, -ENOMEM if memory allocation failed,
80 * or -ENOSPC if no free IDs could be found.
81 */
82int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp)
83{
84 u32 id = start;
85 int ret;
86
87 if (WARN_ON_ONCE(start < 0))
88 return -EINVAL;
89
90 ret = idr_alloc_u32(idr, ptr, &id, end > 0 ? end - 1 : INT_MAX, gfp);
91 if (ret)
92 return ret;
93
94 return id;
95}
96EXPORT_SYMBOL_GPL(idr_alloc);
97
98/**
99 * idr_alloc_cyclic() - Allocate an ID cyclically.
100 * @idr: IDR handle.
101 * @ptr: Pointer to be associated with the new ID.
102 * @start: The minimum ID (inclusive).
103 * @end: The maximum ID (exclusive).
104 * @gfp: Memory allocation flags.
105 *
106 * Allocates an unused ID in the range specified by @nextid and @end. If
107 * @end is <= 0, it is treated as one larger than %INT_MAX. This allows
108 * callers to use @start + N as @end as long as N is within integer range.
109 * The search for an unused ID will start at the last ID allocated and will
110 * wrap around to @start if no free IDs are found before reaching @end.
111 *
112 * The caller should provide their own locking to ensure that two
113 * concurrent modifications to the IDR are not possible. Read-only
114 * accesses to the IDR may be done under the RCU read lock or may
115 * exclude simultaneous writers.
116 *
117 * Return: The newly allocated ID, -ENOMEM if memory allocation failed,
118 * or -ENOSPC if no free IDs could be found.
119 */
120int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp)
121{
122 u32 id = idr->idr_next;
123 int err, max = end > 0 ? end - 1 : INT_MAX;
124
125 if ((int)id < start)
126 id = start;
127
128 err = idr_alloc_u32(idr, ptr, &id, max, gfp);
129 if ((err == -ENOSPC) && (id > start)) {
130 id = start;
131 err = idr_alloc_u32(idr, ptr, &id, max, gfp);
132 }
133 if (err)
134 return err;
135
136 idr->idr_next = id + 1;
137 return id;
138}
139EXPORT_SYMBOL(idr_alloc_cyclic);
140
141/**
142 * idr_remove() - Remove an ID from the IDR.
143 * @idr: IDR handle.
144 * @id: Pointer ID.
145 *
146 * Removes this ID from the IDR. If the ID was not previously in the IDR,
147 * this function returns %NULL.
148 *
149 * Since this function modifies the IDR, the caller should provide their
150 * own locking to ensure that concurrent modification of the same IDR is
151 * not possible.
152 *
153 * Return: The pointer formerly associated with this ID.
154 */
155void *idr_remove(struct idr *idr, unsigned long id)
156{
157 return radix_tree_delete_item(&idr->idr_rt, id - idr->idr_base, NULL);
158}
159EXPORT_SYMBOL_GPL(idr_remove);
160
161/**
162 * idr_find() - Return pointer for given ID.
163 * @idr: IDR handle.
164 * @id: Pointer ID.
165 *
166 * Looks up the pointer associated with this ID. A %NULL pointer may
167 * indicate that @id is not allocated or that the %NULL pointer was
168 * associated with this ID.
169 *
170 * This function can be called under rcu_read_lock(), given that the leaf
171 * pointers lifetimes are correctly managed.
172 *
173 * Return: The pointer associated with this ID.
174 */
175void *idr_find(const struct idr *idr, unsigned long id)
176{
177 return radix_tree_lookup(&idr->idr_rt, id - idr->idr_base);
178}
179EXPORT_SYMBOL_GPL(idr_find);
180
181/**
182 * idr_for_each() - Iterate through all stored pointers.
183 * @idr: IDR handle.
184 * @fn: Function to be called for each pointer.
185 * @data: Data passed to callback function.
186 *
187 * The callback function will be called for each entry in @idr, passing
188 * the ID, the entry and @data.
189 *
190 * If @fn returns anything other than %0, the iteration stops and that
191 * value is returned from this function.
192 *
193 * idr_for_each() can be called concurrently with idr_alloc() and
194 * idr_remove() if protected by RCU. Newly added entries may not be
195 * seen and deleted entries may be seen, but adding and removing entries
196 * will not cause other entries to be skipped, nor spurious ones to be seen.
197 */
198int idr_for_each(const struct idr *idr,
199 int (*fn)(int id, void *p, void *data), void *data)
200{
201 struct radix_tree_iter iter;
202 void __rcu **slot;
203 int base = idr->idr_base;
204
205 radix_tree_for_each_slot(slot, &idr->idr_rt, &iter, 0) {
206 int ret;
207 unsigned long id = iter.index + base;
208
209 if (WARN_ON_ONCE(id > INT_MAX))
210 break;
211 ret = fn(id, rcu_dereference_raw(*slot), data);
212 if (ret)
213 return ret;
214 }
215
216 return 0;
217}
218EXPORT_SYMBOL(idr_for_each);
219
220/**
221 * idr_get_next() - Find next populated entry.
222 * @idr: IDR handle.
223 * @nextid: Pointer to an ID.
224 *
225 * Returns the next populated entry in the tree with an ID greater than
226 * or equal to the value pointed to by @nextid. On exit, @nextid is updated
227 * to the ID of the found value. To use in a loop, the value pointed to by
228 * nextid must be incremented by the user.
229 */
230void *idr_get_next(struct idr *idr, int *nextid)
231{
232 struct radix_tree_iter iter;
233 void __rcu **slot;
234 unsigned long base = idr->idr_base;
235 unsigned long id = *nextid;
236
237 id = (id < base) ? 0 : id - base;
238 slot = radix_tree_iter_find(&idr->idr_rt, &iter, id);
239 if (!slot)
240 return NULL;
241 id = iter.index + base;
242
243 if (WARN_ON_ONCE(id > INT_MAX))
244 return NULL;
245
246 *nextid = id;
247 return rcu_dereference_raw(*slot);
248}
249EXPORT_SYMBOL(idr_get_next);
250
251/**
252 * idr_get_next_ul() - Find next populated entry.
253 * @idr: IDR handle.
254 * @nextid: Pointer to an ID.
255 *
256 * Returns the next populated entry in the tree with an ID greater than
257 * or equal to the value pointed to by @nextid. On exit, @nextid is updated
258 * to the ID of the found value. To use in a loop, the value pointed to by
259 * nextid must be incremented by the user.
260 */
261void *idr_get_next_ul(struct idr *idr, unsigned long *nextid)
262{
263 struct radix_tree_iter iter;
264 void __rcu **slot;
265 unsigned long base = idr->idr_base;
266 unsigned long id = *nextid;
267
268 id = (id < base) ? 0 : id - base;
269 slot = radix_tree_iter_find(&idr->idr_rt, &iter, id);
270 if (!slot)
271 return NULL;
272
273 *nextid = iter.index + base;
274 return rcu_dereference_raw(*slot);
275}
276EXPORT_SYMBOL(idr_get_next_ul);
277
278/**
279 * idr_replace() - replace pointer for given ID.
280 * @idr: IDR handle.
281 * @ptr: New pointer to associate with the ID.
282 * @id: ID to change.
283 *
284 * Replace the pointer registered with an ID and return the old value.
285 * This function can be called under the RCU read lock concurrently with
286 * idr_alloc() and idr_remove() (as long as the ID being removed is not
287 * the one being replaced!).
288 *
289 * Returns: the old value on success. %-ENOENT indicates that @id was not
290 * found. %-EINVAL indicates that @ptr was not valid.
291 */
292void *idr_replace(struct idr *idr, void *ptr, unsigned long id)
293{
294 struct radix_tree_node *node;
295 void __rcu **slot = NULL;
296 void *entry;
297
298 if (WARN_ON_ONCE(radix_tree_is_internal_node(ptr)))
299 return ERR_PTR(-EINVAL);
300 id -= idr->idr_base;
301
302 entry = __radix_tree_lookup(&idr->idr_rt, id, &node, &slot);
303 if (!slot || radix_tree_tag_get(&idr->idr_rt, id, IDR_FREE))
304 return ERR_PTR(-ENOENT);
305
306 __radix_tree_replace(&idr->idr_rt, node, slot, ptr, NULL);
307
308 return entry;
309}
310EXPORT_SYMBOL(idr_replace);
311
312/**
313 * DOC: IDA description
314 *
315 * The IDA is an ID allocator which does not provide the ability to
316 * associate an ID with a pointer. As such, it only needs to store one
317 * bit per ID, and so is more space efficient than an IDR. To use an IDA,
318 * define it using DEFINE_IDA() (or embed a &struct ida in a data structure,
319 * then initialise it using ida_init()). To allocate a new ID, call
320 * ida_simple_get(). To free an ID, call ida_simple_remove().
321 *
322 * If you have more complex locking requirements, use a loop around
323 * ida_pre_get() and ida_get_new() to allocate a new ID. Then use
324 * ida_remove() to free an ID. You must make sure that ida_get_new() and
325 * ida_remove() cannot be called at the same time as each other for the
326 * same IDA.
327 *
328 * You can also use ida_get_new_above() if you need an ID to be allocated
329 * above a particular number. ida_destroy() can be used to dispose of an
330 * IDA without needing to free the individual IDs in it. You can use
331 * ida_is_empty() to find out whether the IDA has any IDs currently allocated.
332 *
333 * IDs are currently limited to the range [0-INT_MAX]. If this is an awkward
334 * limitation, it should be quite straightforward to raise the maximum.
335 */
336
337/*
338 * Developer's notes:
339 *
340 * The IDA uses the functionality provided by the IDR & radix tree to store
341 * bitmaps in each entry. The IDR_FREE tag means there is at least one bit
342 * free, unlike the IDR where it means at least one entry is free.
343 *
344 * I considered telling the radix tree that each slot is an order-10 node
345 * and storing the bit numbers in the radix tree, but the radix tree can't
346 * allow a single multiorder entry at index 0, which would significantly
347 * increase memory consumption for the IDA. So instead we divide the index
348 * by the number of bits in the leaf bitmap before doing a radix tree lookup.
349 *
350 * As an optimisation, if there are only a few low bits set in any given
351 * leaf, instead of allocating a 128-byte bitmap, we use the 'exceptional
352 * entry' functionality of the radix tree to store BITS_PER_LONG - 2 bits
353 * directly in the entry. By being really tricksy, we could store
354 * BITS_PER_LONG - 1 bits, but there're diminishing returns after optimising
355 * for 0-3 allocated IDs.
356 *
357 * We allow the radix tree 'exceptional' count to get out of date. Nothing
358 * in the IDA nor the radix tree code checks it. If it becomes important
359 * to maintain an accurate exceptional count, switch the rcu_assign_pointer()
360 * calls to radix_tree_iter_replace() which will correct the exceptional
361 * count.
362 *
363 * The IDA always requires a lock to alloc/free. If we add a 'test_bit'
364 * equivalent, it will still need locking. Going to RCU lookup would require
365 * using RCU to free bitmaps, and that's not trivial without embedding an
366 * RCU head in the bitmap, which adds a 2-pointer overhead to each 128-byte
367 * bitmap, which is excessive.
368 */
369
370#define IDA_MAX (0x80000000U / IDA_BITMAP_BITS - 1)
371
372/**
373 * ida_get_new_above - allocate new ID above or equal to a start id
374 * @ida: ida handle
375 * @start: id to start search at
376 * @id: pointer to the allocated handle
377 *
378 * Allocate new ID above or equal to @start. It should be called
379 * with any required locks to ensure that concurrent calls to
380 * ida_get_new_above() / ida_get_new() / ida_remove() are not allowed.
381 * Consider using ida_simple_get() if you do not have complex locking
382 * requirements.
383 *
384 * If memory is required, it will return %-EAGAIN, you should unlock
385 * and go back to the ida_pre_get() call. If the ida is full, it will
386 * return %-ENOSPC. On success, it will return 0.
387 *
388 * @id returns a value in the range @start ... %0x7fffffff.
389 */
390int ida_get_new_above(struct ida *ida, int start, int *id)
391{
392 struct radix_tree_root *root = &ida->ida_rt;
393 void __rcu **slot;
394 struct radix_tree_iter iter;
395 struct ida_bitmap *bitmap;
396 unsigned long index;
397 unsigned bit, ebit;
398 int new;
399
400 index = start / IDA_BITMAP_BITS;
401 bit = start % IDA_BITMAP_BITS;
402 ebit = bit + RADIX_TREE_EXCEPTIONAL_SHIFT;
403
404 slot = radix_tree_iter_init(&iter, index);
405 for (;;) {
406 if (slot)
407 slot = radix_tree_next_slot(slot, &iter,
408 RADIX_TREE_ITER_TAGGED);
409 if (!slot) {
410 slot = idr_get_free(root, &iter, GFP_NOWAIT, IDA_MAX);
411 if (IS_ERR(slot)) {
412 if (slot == ERR_PTR(-ENOMEM))
413 return -EAGAIN;
414 return PTR_ERR(slot);
415 }
416 }
417 if (iter.index > index) {
418 bit = 0;
419 ebit = RADIX_TREE_EXCEPTIONAL_SHIFT;
420 }
421 new = iter.index * IDA_BITMAP_BITS;
422 bitmap = rcu_dereference_raw(*slot);
423 if (radix_tree_exception(bitmap)) {
424 unsigned long tmp = (unsigned long)bitmap;
425 ebit = find_next_zero_bit(&tmp, BITS_PER_LONG, ebit);
426 if (ebit < BITS_PER_LONG) {
427 tmp |= 1UL << ebit;
428 rcu_assign_pointer(*slot, (void *)tmp);
429 *id = new + ebit - RADIX_TREE_EXCEPTIONAL_SHIFT;
430 return 0;
431 }
432 bitmap = this_cpu_xchg(ida_bitmap, NULL);
433 if (!bitmap)
434 return -EAGAIN;
435 bitmap->bitmap[0] = tmp >> RADIX_TREE_EXCEPTIONAL_SHIFT;
436 rcu_assign_pointer(*slot, bitmap);
437 }
438
439 if (bitmap) {
440 bit = find_next_zero_bit(bitmap->bitmap,
441 IDA_BITMAP_BITS, bit);
442 new += bit;
443 if (new < 0)
444 return -ENOSPC;
445 if (bit == IDA_BITMAP_BITS)
446 continue;
447
448 __set_bit(bit, bitmap->bitmap);
449 if (bitmap_full(bitmap->bitmap, IDA_BITMAP_BITS))
450 radix_tree_iter_tag_clear(root, &iter,
451 IDR_FREE);
452 } else {
453 new += bit;
454 if (new < 0)
455 return -ENOSPC;
456 if (ebit < BITS_PER_LONG) {
457 bitmap = (void *)((1UL << ebit) |
458 RADIX_TREE_EXCEPTIONAL_ENTRY);
459 radix_tree_iter_replace(root, &iter, slot,
460 bitmap);
461 *id = new;
462 return 0;
463 }
464 bitmap = this_cpu_xchg(ida_bitmap, NULL);
465 if (!bitmap)
466 return -EAGAIN;
467 __set_bit(bit, bitmap->bitmap);
468 radix_tree_iter_replace(root, &iter, slot, bitmap);
469 }
470
471 *id = new;
472 return 0;
473 }
474}
475EXPORT_SYMBOL(ida_get_new_above);
476
477/**
478 * ida_remove - Free the given ID
479 * @ida: ida handle
480 * @id: ID to free
481 *
482 * This function should not be called at the same time as ida_get_new_above().
483 */
484void ida_remove(struct ida *ida, int id)
485{
486 unsigned long index = id / IDA_BITMAP_BITS;
487 unsigned offset = id % IDA_BITMAP_BITS;
488 struct ida_bitmap *bitmap;
489 unsigned long *btmp;
490 struct radix_tree_iter iter;
491 void __rcu **slot;
492
493 slot = radix_tree_iter_lookup(&ida->ida_rt, &iter, index);
494 if (!slot)
495 goto err;
496
497 bitmap = rcu_dereference_raw(*slot);
498 if (radix_tree_exception(bitmap)) {
499 btmp = (unsigned long *)slot;
500 offset += RADIX_TREE_EXCEPTIONAL_SHIFT;
501 if (offset >= BITS_PER_LONG)
502 goto err;
503 } else {
504 btmp = bitmap->bitmap;
505 }
506 if (!test_bit(offset, btmp))
507 goto err;
508
509 __clear_bit(offset, btmp);
510 radix_tree_iter_tag_set(&ida->ida_rt, &iter, IDR_FREE);
511 if (radix_tree_exception(bitmap)) {
512 if (rcu_dereference_raw(*slot) ==
513 (void *)RADIX_TREE_EXCEPTIONAL_ENTRY)
514 radix_tree_iter_delete(&ida->ida_rt, &iter, slot);
515 } else if (bitmap_empty(btmp, IDA_BITMAP_BITS)) {
516 kfree(bitmap);
517 radix_tree_iter_delete(&ida->ida_rt, &iter, slot);
518 }
519 return;
520 err:
521 WARN(1, "ida_remove called for id=%d which is not allocated.\n", id);
522}
523EXPORT_SYMBOL(ida_remove);
524
525/**
526 * ida_destroy - Free the contents of an ida
527 * @ida: ida handle
528 *
529 * Calling this function releases all resources associated with an IDA. When
530 * this call returns, the IDA is empty and can be reused or freed. The caller
531 * should not allow ida_remove() or ida_get_new_above() to be called at the
532 * same time.
533 */
534void ida_destroy(struct ida *ida)
535{
536 struct radix_tree_iter iter;
537 void __rcu **slot;
538
539 radix_tree_for_each_slot(slot, &ida->ida_rt, &iter, 0) {
540 struct ida_bitmap *bitmap = rcu_dereference_raw(*slot);
541 if (!radix_tree_exception(bitmap))
542 kfree(bitmap);
543 radix_tree_iter_delete(&ida->ida_rt, &iter, slot);
544 }
545}
546EXPORT_SYMBOL(ida_destroy);
547
548/**
549 * ida_simple_get - get a new id.
550 * @ida: the (initialized) ida.
551 * @start: the minimum id (inclusive, < 0x8000000)
552 * @end: the maximum id (exclusive, < 0x8000000 or 0)
553 * @gfp_mask: memory allocation flags
554 *
555 * Allocates an id in the range start <= id < end, or returns -ENOSPC.
556 * On memory allocation failure, returns -ENOMEM.
557 *
558 * Compared to ida_get_new_above() this function does its own locking, and
559 * should be used unless there are special requirements.
560 *
561 * Use ida_simple_remove() to get rid of an id.
562 */
563int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
564 gfp_t gfp_mask)
565{
566 int ret, id;
567 unsigned int max;
568 unsigned long flags;
569
570 BUG_ON((int)start < 0);
571 BUG_ON((int)end < 0);
572
573 if (end == 0)
574 max = 0x80000000;
575 else {
576 BUG_ON(end < start);
577 max = end - 1;
578 }
579
580again:
581 if (!ida_pre_get(ida, gfp_mask))
582 return -ENOMEM;
583
584 spin_lock_irqsave(&simple_ida_lock, flags);
585 ret = ida_get_new_above(ida, start, &id);
586 if (!ret) {
587 if (id > max) {
588 ida_remove(ida, id);
589 ret = -ENOSPC;
590 } else {
591 ret = id;
592 }
593 }
594 spin_unlock_irqrestore(&simple_ida_lock, flags);
595
596 if (unlikely(ret == -EAGAIN))
597 goto again;
598
599 return ret;
600}
601EXPORT_SYMBOL(ida_simple_get);
602
603/**
604 * ida_simple_remove - remove an allocated id.
605 * @ida: the (initialized) ida.
606 * @id: the id returned by ida_simple_get.
607 *
608 * Use to release an id allocated with ida_simple_get().
609 *
610 * Compared to ida_remove() this function does its own locking, and should be
611 * used unless there are special requirements.
612 */
613void ida_simple_remove(struct ida *ida, unsigned int id)
614{
615 unsigned long flags;
616
617 BUG_ON((int)id < 0);
618 spin_lock_irqsave(&simple_ida_lock, flags);
619 ida_remove(ida, id);
620 spin_unlock_irqrestore(&simple_ida_lock, flags);
621}
622EXPORT_SYMBOL(ida_simple_remove);