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