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