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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// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/bitmap.h>
3#include <linux/bug.h>
4#include <linux/export.h>
5#include <linux/idr.h>
6#include <linux/slab.h>
7#include <linux/spinlock.h>
8#include <linux/xarray.h>
9
10/**
11 * idr_alloc_u32() - Allocate an ID.
12 * @idr: IDR handle.
13 * @ptr: Pointer to be associated with the new ID.
14 * @nextid: Pointer to an ID.
15 * @max: The maximum ID to allocate (inclusive).
16 * @gfp: Memory allocation flags.
17 *
18 * Allocates an unused ID in the range specified by @nextid and @max.
19 * Note that @max is inclusive whereas the @end parameter to idr_alloc()
20 * is exclusive. The new ID is assigned to @nextid before the pointer
21 * is inserted into the IDR, so if @nextid points into the object pointed
22 * to by @ptr, a concurrent lookup will not find an uninitialised ID.
23 *
24 * The caller should provide their own locking to ensure that two
25 * concurrent modifications to the IDR are not possible. Read-only
26 * accesses to the IDR may be done under the RCU read lock or may
27 * exclude simultaneous writers.
28 *
29 * Return: 0 if an ID was allocated, -ENOMEM if memory allocation failed,
30 * or -ENOSPC if no free IDs could be found. If an error occurred,
31 * @nextid is unchanged.
32 */
33int idr_alloc_u32(struct idr *idr, void *ptr, u32 *nextid,
34 unsigned long max, gfp_t gfp)
35{
36 struct radix_tree_iter iter;
37 void __rcu **slot;
38 unsigned int base = idr->idr_base;
39 unsigned int id = *nextid;
40
41 if (WARN_ON_ONCE(!(idr->idr_rt.xa_flags & ROOT_IS_IDR)))
42 idr->idr_rt.xa_flags |= IDR_RT_MARKER;
43
44 id = (id < base) ? 0 : id - base;
45 radix_tree_iter_init(&iter, id);
46 slot = idr_get_free(&idr->idr_rt, &iter, gfp, max - base);
47 if (IS_ERR(slot))
48 return PTR_ERR(slot);
49
50 *nextid = iter.index + base;
51 /* there is a memory barrier inside radix_tree_iter_replace() */
52 radix_tree_iter_replace(&idr->idr_rt, &iter, slot, ptr);
53 radix_tree_iter_tag_clear(&idr->idr_rt, &iter, IDR_FREE);
54
55 return 0;
56}
57EXPORT_SYMBOL_GPL(idr_alloc_u32);
58
59/**
60 * idr_alloc() - Allocate an ID.
61 * @idr: IDR handle.
62 * @ptr: Pointer to be associated with the new ID.
63 * @start: The minimum ID (inclusive).
64 * @end: The maximum ID (exclusive).
65 * @gfp: Memory allocation flags.
66 *
67 * Allocates an unused ID in the range specified by @start and @end. If
68 * @end is <= 0, it is treated as one larger than %INT_MAX. This allows
69 * callers to use @start + N as @end as long as N is within integer range.
70 *
71 * The caller should provide their own locking to ensure that two
72 * concurrent modifications to the IDR are not possible. Read-only
73 * accesses to the IDR may be done under the RCU read lock or may
74 * exclude simultaneous writers.
75 *
76 * Return: The newly allocated ID, -ENOMEM if memory allocation failed,
77 * or -ENOSPC if no free IDs could be found.
78 */
79int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp)
80{
81 u32 id = start;
82 int ret;
83
84 if (WARN_ON_ONCE(start < 0))
85 return -EINVAL;
86
87 ret = idr_alloc_u32(idr, ptr, &id, end > 0 ? end - 1 : INT_MAX, gfp);
88 if (ret)
89 return ret;
90
91 return id;
92}
93EXPORT_SYMBOL_GPL(idr_alloc);
94
95/**
96 * idr_alloc_cyclic() - Allocate an ID cyclically.
97 * @idr: IDR handle.
98 * @ptr: Pointer to be associated with the new ID.
99 * @start: The minimum ID (inclusive).
100 * @end: The maximum ID (exclusive).
101 * @gfp: Memory allocation flags.
102 *
103 * Allocates an unused ID in the range specified by @start and @end. If
104 * @end is <= 0, it is treated as one larger than %INT_MAX. This allows
105 * callers to use @start + N as @end as long as N is within integer range.
106 * The search for an unused ID will start at the last ID allocated and will
107 * wrap around to @start if no free IDs are found before reaching @end.
108 *
109 * The caller should provide their own locking to ensure that two
110 * concurrent modifications to the IDR are not possible. Read-only
111 * accesses to the IDR may be done under the RCU read lock or may
112 * exclude simultaneous writers.
113 *
114 * Return: The newly allocated ID, -ENOMEM if memory allocation failed,
115 * or -ENOSPC if no free IDs could be found.
116 */
117int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp)
118{
119 u32 id = idr->idr_next;
120 int err, max = end > 0 ? end - 1 : INT_MAX;
121
122 if ((int)id < start)
123 id = start;
124
125 err = idr_alloc_u32(idr, ptr, &id, max, gfp);
126 if ((err == -ENOSPC) && (id > start)) {
127 id = start;
128 err = idr_alloc_u32(idr, ptr, &id, max, gfp);
129 }
130 if (err)
131 return err;
132
133 idr->idr_next = id + 1;
134 return id;
135}
136EXPORT_SYMBOL(idr_alloc_cyclic);
137
138/**
139 * idr_remove() - Remove an ID from the IDR.
140 * @idr: IDR handle.
141 * @id: Pointer ID.
142 *
143 * Removes this ID from the IDR. If the ID was not previously in the IDR,
144 * this function returns %NULL.
145 *
146 * Since this function modifies the IDR, the caller should provide their
147 * own locking to ensure that concurrent modification of the same IDR is
148 * not possible.
149 *
150 * Return: The pointer formerly associated with this ID.
151 */
152void *idr_remove(struct idr *idr, unsigned long id)
153{
154 return radix_tree_delete_item(&idr->idr_rt, id - idr->idr_base, NULL);
155}
156EXPORT_SYMBOL_GPL(idr_remove);
157
158/**
159 * idr_find() - Return pointer for given ID.
160 * @idr: IDR handle.
161 * @id: Pointer ID.
162 *
163 * Looks up the pointer associated with this ID. A %NULL pointer may
164 * indicate that @id is not allocated or that the %NULL pointer was
165 * associated with this ID.
166 *
167 * This function can be called under rcu_read_lock(), given that the leaf
168 * pointers lifetimes are correctly managed.
169 *
170 * Return: The pointer associated with this ID.
171 */
172void *idr_find(const struct idr *idr, unsigned long id)
173{
174 return radix_tree_lookup(&idr->idr_rt, id - idr->idr_base);
175}
176EXPORT_SYMBOL_GPL(idr_find);
177
178/**
179 * idr_for_each() - Iterate through all stored pointers.
180 * @idr: IDR handle.
181 * @fn: Function to be called for each pointer.
182 * @data: Data passed to callback function.
183 *
184 * The callback function will be called for each entry in @idr, passing
185 * the ID, the entry and @data.
186 *
187 * If @fn returns anything other than %0, the iteration stops and that
188 * value is returned from this function.
189 *
190 * idr_for_each() can be called concurrently with idr_alloc() and
191 * idr_remove() if protected by RCU. Newly added entries may not be
192 * seen and deleted entries may be seen, but adding and removing entries
193 * will not cause other entries to be skipped, nor spurious ones to be seen.
194 */
195int idr_for_each(const struct idr *idr,
196 int (*fn)(int id, void *p, void *data), void *data)
197{
198 struct radix_tree_iter iter;
199 void __rcu **slot;
200 int base = idr->idr_base;
201
202 radix_tree_for_each_slot(slot, &idr->idr_rt, &iter, 0) {
203 int ret;
204 unsigned long id = iter.index + base;
205
206 if (WARN_ON_ONCE(id > INT_MAX))
207 break;
208 ret = fn(id, rcu_dereference_raw(*slot), data);
209 if (ret)
210 return ret;
211 }
212
213 return 0;
214}
215EXPORT_SYMBOL(idr_for_each);
216
217/**
218 * idr_get_next_ul() - Find next populated entry.
219 * @idr: IDR handle.
220 * @nextid: Pointer to an ID.
221 *
222 * Returns the next populated entry in the tree with an ID greater than
223 * or equal to the value pointed to by @nextid. On exit, @nextid is updated
224 * to the ID of the found value. To use in a loop, the value pointed to by
225 * nextid must be incremented by the user.
226 */
227void *idr_get_next_ul(struct idr *idr, unsigned long *nextid)
228{
229 struct radix_tree_iter iter;
230 void __rcu **slot;
231 void *entry = NULL;
232 unsigned long base = idr->idr_base;
233 unsigned long id = *nextid;
234
235 id = (id < base) ? 0 : id - base;
236 radix_tree_for_each_slot(slot, &idr->idr_rt, &iter, id) {
237 entry = rcu_dereference_raw(*slot);
238 if (!entry)
239 continue;
240 if (!xa_is_internal(entry))
241 break;
242 if (slot != &idr->idr_rt.xa_head && !xa_is_retry(entry))
243 break;
244 slot = radix_tree_iter_retry(&iter);
245 }
246 if (!slot)
247 return NULL;
248
249 *nextid = iter.index + base;
250 return entry;
251}
252EXPORT_SYMBOL(idr_get_next_ul);
253
254/**
255 * idr_get_next() - Find next populated entry.
256 * @idr: IDR handle.
257 * @nextid: Pointer to an ID.
258 *
259 * Returns the next populated entry in the tree with an ID greater than
260 * or equal to the value pointed to by @nextid. On exit, @nextid is updated
261 * to the ID of the found value. To use in a loop, the value pointed to by
262 * nextid must be incremented by the user.
263 */
264void *idr_get_next(struct idr *idr, int *nextid)
265{
266 unsigned long id = *nextid;
267 void *entry = idr_get_next_ul(idr, &id);
268
269 if (WARN_ON_ONCE(id > INT_MAX))
270 return NULL;
271 *nextid = id;
272 return entry;
273}
274EXPORT_SYMBOL(idr_get_next);
275
276/**
277 * idr_replace() - replace pointer for given ID.
278 * @idr: IDR handle.
279 * @ptr: New pointer to associate with the ID.
280 * @id: ID to change.
281 *
282 * Replace the pointer registered with an ID and return the old value.
283 * This function can be called under the RCU read lock concurrently with
284 * idr_alloc() and idr_remove() (as long as the ID being removed is not
285 * the one being replaced!).
286 *
287 * Returns: the old value on success. %-ENOENT indicates that @id was not
288 * found. %-EINVAL indicates that @ptr was not valid.
289 */
290void *idr_replace(struct idr *idr, void *ptr, unsigned long id)
291{
292 struct radix_tree_node *node;
293 void __rcu **slot = NULL;
294 void *entry;
295
296 id -= idr->idr_base;
297
298 entry = __radix_tree_lookup(&idr->idr_rt, id, &node, &slot);
299 if (!slot || radix_tree_tag_get(&idr->idr_rt, id, IDR_FREE))
300 return ERR_PTR(-ENOENT);
301
302 __radix_tree_replace(&idr->idr_rt, node, slot, ptr);
303
304 return entry;
305}
306EXPORT_SYMBOL(idr_replace);
307
308/**
309 * DOC: IDA description
310 *
311 * The IDA is an ID allocator which does not provide the ability to
312 * associate an ID with a pointer. As such, it only needs to store one
313 * bit per ID, and so is more space efficient than an IDR. To use an IDA,
314 * define it using DEFINE_IDA() (or embed a &struct ida in a data structure,
315 * then initialise it using ida_init()). To allocate a new ID, call
316 * ida_alloc(), ida_alloc_min(), ida_alloc_max() or ida_alloc_range().
317 * To free an ID, call ida_free().
318 *
319 * ida_destroy() can be used to dispose of an IDA without needing to
320 * free the individual IDs in it. You can use ida_is_empty() to find
321 * out whether the IDA has any IDs currently allocated.
322 *
323 * The IDA handles its own locking. It is safe to call any of the IDA
324 * functions without synchronisation in your code.
325 *
326 * IDs are currently limited to the range [0-INT_MAX]. If this is an awkward
327 * limitation, it should be quite straightforward to raise the maximum.
328 */
329
330/*
331 * Developer's notes:
332 *
333 * The IDA uses the functionality provided by the XArray to store bitmaps in
334 * each entry. The XA_FREE_MARK is only cleared when all bits in the bitmap
335 * have been set.
336 *
337 * I considered telling the XArray that each slot is an order-10 node
338 * and indexing by bit number, but the XArray can't allow a single multi-index
339 * entry in the head, which would significantly increase memory consumption
340 * for the IDA. So instead we divide the index by the number of bits in the
341 * leaf bitmap before doing a radix tree lookup.
342 *
343 * As an optimisation, if there are only a few low bits set in any given
344 * leaf, instead of allocating a 128-byte bitmap, we store the bits
345 * as a value entry. Value entries never have the XA_FREE_MARK cleared
346 * because we can always convert them into a bitmap entry.
347 *
348 * It would be possible to optimise further; once we've run out of a
349 * single 128-byte bitmap, we currently switch to a 576-byte node, put
350 * the 128-byte bitmap in the first entry and then start allocating extra
351 * 128-byte entries. We could instead use the 512 bytes of the node's
352 * data as a bitmap before moving to that scheme. I do not believe this
353 * is a worthwhile optimisation; Rasmus Villemoes surveyed the current
354 * users of the IDA and almost none of them use more than 1024 entries.
355 * Those that do use more than the 8192 IDs that the 512 bytes would
356 * provide.
357 *
358 * The IDA always uses a lock to alloc/free. If we add a 'test_bit'
359 * equivalent, it will still need locking. Going to RCU lookup would require
360 * using RCU to free bitmaps, and that's not trivial without embedding an
361 * RCU head in the bitmap, which adds a 2-pointer overhead to each 128-byte
362 * bitmap, which is excessive.
363 */
364
365/**
366 * ida_alloc_range() - Allocate an unused ID.
367 * @ida: IDA handle.
368 * @min: Lowest ID to allocate.
369 * @max: Highest ID to allocate.
370 * @gfp: Memory allocation flags.
371 *
372 * Allocate an ID between @min and @max, inclusive. The allocated ID will
373 * not exceed %INT_MAX, even if @max is larger.
374 *
375 * Context: Any context. It is safe to call this function without
376 * locking in your code.
377 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
378 * or %-ENOSPC if there are no free IDs.
379 */
380int ida_alloc_range(struct ida *ida, unsigned int min, unsigned int max,
381 gfp_t gfp)
382{
383 XA_STATE(xas, &ida->xa, min / IDA_BITMAP_BITS);
384 unsigned bit = min % IDA_BITMAP_BITS;
385 unsigned long flags;
386 struct ida_bitmap *bitmap, *alloc = NULL;
387
388 if ((int)min < 0)
389 return -ENOSPC;
390
391 if ((int)max < 0)
392 max = INT_MAX;
393
394retry:
395 xas_lock_irqsave(&xas, flags);
396next:
397 bitmap = xas_find_marked(&xas, max / IDA_BITMAP_BITS, XA_FREE_MARK);
398 if (xas.xa_index > min / IDA_BITMAP_BITS)
399 bit = 0;
400 if (xas.xa_index * IDA_BITMAP_BITS + bit > max)
401 goto nospc;
402
403 if (xa_is_value(bitmap)) {
404 unsigned long tmp = xa_to_value(bitmap);
405
406 if (bit < BITS_PER_XA_VALUE) {
407 bit = find_next_zero_bit(&tmp, BITS_PER_XA_VALUE, bit);
408 if (xas.xa_index * IDA_BITMAP_BITS + bit > max)
409 goto nospc;
410 if (bit < BITS_PER_XA_VALUE) {
411 tmp |= 1UL << bit;
412 xas_store(&xas, xa_mk_value(tmp));
413 goto out;
414 }
415 }
416 bitmap = alloc;
417 if (!bitmap)
418 bitmap = kzalloc(sizeof(*bitmap), GFP_NOWAIT);
419 if (!bitmap)
420 goto alloc;
421 bitmap->bitmap[0] = tmp;
422 xas_store(&xas, bitmap);
423 if (xas_error(&xas)) {
424 bitmap->bitmap[0] = 0;
425 goto out;
426 }
427 }
428
429 if (bitmap) {
430 bit = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, bit);
431 if (xas.xa_index * IDA_BITMAP_BITS + bit > max)
432 goto nospc;
433 if (bit == IDA_BITMAP_BITS)
434 goto next;
435
436 __set_bit(bit, bitmap->bitmap);
437 if (bitmap_full(bitmap->bitmap, IDA_BITMAP_BITS))
438 xas_clear_mark(&xas, XA_FREE_MARK);
439 } else {
440 if (bit < BITS_PER_XA_VALUE) {
441 bitmap = xa_mk_value(1UL << bit);
442 } else {
443 bitmap = alloc;
444 if (!bitmap)
445 bitmap = kzalloc(sizeof(*bitmap), GFP_NOWAIT);
446 if (!bitmap)
447 goto alloc;
448 __set_bit(bit, bitmap->bitmap);
449 }
450 xas_store(&xas, bitmap);
451 }
452out:
453 xas_unlock_irqrestore(&xas, flags);
454 if (xas_nomem(&xas, gfp)) {
455 xas.xa_index = min / IDA_BITMAP_BITS;
456 bit = min % IDA_BITMAP_BITS;
457 goto retry;
458 }
459 if (bitmap != alloc)
460 kfree(alloc);
461 if (xas_error(&xas))
462 return xas_error(&xas);
463 return xas.xa_index * IDA_BITMAP_BITS + bit;
464alloc:
465 xas_unlock_irqrestore(&xas, flags);
466 alloc = kzalloc(sizeof(*bitmap), gfp);
467 if (!alloc)
468 return -ENOMEM;
469 xas_set(&xas, min / IDA_BITMAP_BITS);
470 bit = min % IDA_BITMAP_BITS;
471 goto retry;
472nospc:
473 xas_unlock_irqrestore(&xas, flags);
474 kfree(alloc);
475 return -ENOSPC;
476}
477EXPORT_SYMBOL(ida_alloc_range);
478
479/**
480 * ida_free() - Release an allocated ID.
481 * @ida: IDA handle.
482 * @id: Previously allocated ID.
483 *
484 * Context: Any context. It is safe to call this function without
485 * locking in your code.
486 */
487void ida_free(struct ida *ida, unsigned int id)
488{
489 XA_STATE(xas, &ida->xa, id / IDA_BITMAP_BITS);
490 unsigned bit = id % IDA_BITMAP_BITS;
491 struct ida_bitmap *bitmap;
492 unsigned long flags;
493
494 if ((int)id < 0)
495 return;
496
497 xas_lock_irqsave(&xas, flags);
498 bitmap = xas_load(&xas);
499
500 if (xa_is_value(bitmap)) {
501 unsigned long v = xa_to_value(bitmap);
502 if (bit >= BITS_PER_XA_VALUE)
503 goto err;
504 if (!(v & (1UL << bit)))
505 goto err;
506 v &= ~(1UL << bit);
507 if (!v)
508 goto delete;
509 xas_store(&xas, xa_mk_value(v));
510 } else {
511 if (!bitmap || !test_bit(bit, bitmap->bitmap))
512 goto err;
513 __clear_bit(bit, bitmap->bitmap);
514 xas_set_mark(&xas, XA_FREE_MARK);
515 if (bitmap_empty(bitmap->bitmap, IDA_BITMAP_BITS)) {
516 kfree(bitmap);
517delete:
518 xas_store(&xas, NULL);
519 }
520 }
521 xas_unlock_irqrestore(&xas, flags);
522 return;
523 err:
524 xas_unlock_irqrestore(&xas, flags);
525 WARN(1, "ida_free called for id=%d which is not allocated.\n", id);
526}
527EXPORT_SYMBOL(ida_free);
528
529/**
530 * ida_destroy() - Free all IDs.
531 * @ida: IDA handle.
532 *
533 * Calling this function frees all IDs and releases all resources used
534 * by an IDA. When this call returns, the IDA is empty and can be reused
535 * or freed. If the IDA is already empty, there is no need to call this
536 * function.
537 *
538 * Context: Any context. It is safe to call this function without
539 * locking in your code.
540 */
541void ida_destroy(struct ida *ida)
542{
543 XA_STATE(xas, &ida->xa, 0);
544 struct ida_bitmap *bitmap;
545 unsigned long flags;
546
547 xas_lock_irqsave(&xas, flags);
548 xas_for_each(&xas, bitmap, ULONG_MAX) {
549 if (!xa_is_value(bitmap))
550 kfree(bitmap);
551 xas_store(&xas, NULL);
552 }
553 xas_unlock_irqrestore(&xas, flags);
554}
555EXPORT_SYMBOL(ida_destroy);
556
557#ifndef __KERNEL__
558extern void xa_dump_index(unsigned long index, unsigned int shift);
559#define IDA_CHUNK_SHIFT ilog2(IDA_BITMAP_BITS)
560
561static void ida_dump_entry(void *entry, unsigned long index)
562{
563 unsigned long i;
564
565 if (!entry)
566 return;
567
568 if (xa_is_node(entry)) {
569 struct xa_node *node = xa_to_node(entry);
570 unsigned int shift = node->shift + IDA_CHUNK_SHIFT +
571 XA_CHUNK_SHIFT;
572
573 xa_dump_index(index * IDA_BITMAP_BITS, shift);
574 xa_dump_node(node);
575 for (i = 0; i < XA_CHUNK_SIZE; i++)
576 ida_dump_entry(node->slots[i],
577 index | (i << node->shift));
578 } else if (xa_is_value(entry)) {
579 xa_dump_index(index * IDA_BITMAP_BITS, ilog2(BITS_PER_LONG));
580 pr_cont("value: data %lx [%px]\n", xa_to_value(entry), entry);
581 } else {
582 struct ida_bitmap *bitmap = entry;
583
584 xa_dump_index(index * IDA_BITMAP_BITS, IDA_CHUNK_SHIFT);
585 pr_cont("bitmap: %p data", bitmap);
586 for (i = 0; i < IDA_BITMAP_LONGS; i++)
587 pr_cont(" %lx", bitmap->bitmap[i]);
588 pr_cont("\n");
589 }
590}
591
592static void ida_dump(struct ida *ida)
593{
594 struct xarray *xa = &ida->xa;
595 pr_debug("ida: %p node %p free %d\n", ida, xa->xa_head,
596 xa->xa_flags >> ROOT_TAG_SHIFT);
597 ida_dump_entry(xa->xa_head, 0);
598}
599#endif