summaryrefslogtreecommitdiff
path: root/lib/genalloc.c
blob: 144fe6b1a03ea536893f6e35d153a895a238b67d (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
/*
 * Basic general purpose allocator for managing special purpose
 * memory, for example, memory that is not managed by the regular
 * kmalloc/kfree interface.  Uses for this includes on-device special
 * memory, uncached memory etc.
 *
 * It is safe to use the allocator in NMI handlers and other special
 * unblockable contexts that could otherwise deadlock on locks.  This
 * is implemented by using atomic operations and retries on any
 * conflicts.  The disadvantage is that there may be livelocks in
 * extreme cases.  For better scalability, one allocator can be used
 * for each CPU.
 *
 * The lockless operation only works if there is enough memory
 * available.  If new memory is added to the pool a lock has to be
 * still taken.  So any user relying on locklessness has to ensure
 * that sufficient memory is preallocated.
 *
 * The basic atomic operation of this allocator is cmpxchg on long.
 * On architectures that don't have NMI-safe cmpxchg implementation,
 * the allocator can NOT be used in NMI handler.  So code uses the
 * allocator in NMI handler should depend on
 * CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
 *
 * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 */

#include <linux/slab.h>
#include <linux/export.h>
#include <linux/bitmap.h>
#include <linux/rculist.h>
#include <linux/interrupt.h>
#include <linux/genalloc.h>
#include <linux/of_device.h>

static inline size_t chunk_size(const struct gen_pool_chunk *chunk)
{
	return chunk->end_addr - chunk->start_addr + 1;
}

static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)
{
	unsigned long val, nval;

	nval = *addr;
	do {
		val = nval;
		if (val & mask_to_set)
			return -EBUSY;
		cpu_relax();
	} while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val);

	return 0;
}

static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear)
{
	unsigned long val, nval;

	nval = *addr;
	do {
		val = nval;
		if ((val & mask_to_clear) != mask_to_clear)
			return -EBUSY;
		cpu_relax();
	} while ((nval = cmpxchg(addr, val, val & ~mask_to_clear)) != val);

	return 0;
}

/*
 * bitmap_set_ll - set the specified number of bits at the specified position
 * @map: pointer to a bitmap
 * @start: a bit position in @map
 * @nr: number of bits to set
 *
 * Set @nr bits start from @start in @map lock-lessly. Several users
 * can set/clear the same bitmap simultaneously without lock. If two
 * users set the same bit, one user will return remain bits, otherwise
 * return 0.
 */
static int bitmap_set_ll(unsigned long *map, int start, int nr)
{
	unsigned long *p = map + BIT_WORD(start);
	const int size = start + nr;
	int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
	unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);

	while (nr - bits_to_set >= 0) {
		if (set_bits_ll(p, mask_to_set))
			return nr;
		nr -= bits_to_set;
		bits_to_set = BITS_PER_LONG;
		mask_to_set = ~0UL;
		p++;
	}
	if (nr) {
		mask_to_set &= BITMAP_LAST_WORD_MASK(size);
		if (set_bits_ll(p, mask_to_set))
			return nr;
	}

	return 0;
}

/*
 * bitmap_clear_ll - clear the specified number of bits at the specified position
 * @map: pointer to a bitmap
 * @start: a bit position in @map
 * @nr: number of bits to set
 *
 * Clear @nr bits start from @start in @map lock-lessly. Several users
 * can set/clear the same bitmap simultaneously without lock. If two
 * users clear the same bit, one user will return remain bits,
 * otherwise return 0.
 */
static int bitmap_clear_ll(unsigned long *map, int start, int nr)
{
	unsigned long *p = map + BIT_WORD(start);
	const int size = start + nr;
	int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
	unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);

	while (nr - bits_to_clear >= 0) {
		if (clear_bits_ll(p, mask_to_clear))
			return nr;
		nr -= bits_to_clear;
		bits_to_clear = BITS_PER_LONG;
		mask_to_clear = ~0UL;
		p++;
	}
	if (nr) {
		mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
		if (clear_bits_ll(p, mask_to_clear))
			return nr;
	}

	return 0;
}

/**
 * gen_pool_create - create a new special memory pool
 * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
 * @nid: node id of the node the pool structure should be allocated on, or -1
 *
 * Create a new special memory pool that can be used to manage special purpose
 * memory not managed by the regular kmalloc/kfree interface.
 */
struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
{
	struct gen_pool *pool;

	pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);
	if (pool != NULL) {
		spin_lock_init(&pool->lock);
		INIT_LIST_HEAD(&pool->chunks);
		pool->min_alloc_order = min_alloc_order;
		pool->algo = gen_pool_first_fit;
		pool->data = NULL;
		pool->name = NULL;
	}
	return pool;
}
EXPORT_SYMBOL(gen_pool_create);

/**
 * gen_pool_add_virt - add a new chunk of special memory to the pool
 * @pool: pool to add new memory chunk to
 * @virt: virtual starting address of memory chunk to add to pool
 * @phys: physical starting address of memory chunk to add to pool
 * @size: size in bytes of the memory chunk to add to pool
 * @nid: node id of the node the chunk structure and bitmap should be
 *       allocated on, or -1
 *
 * Add a new chunk of special memory to the specified pool.
 *
 * Returns 0 on success or a -ve errno on failure.
 */
int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt, phys_addr_t phys,
		 size_t size, int nid)
{
	struct gen_pool_chunk *chunk;
	int nbits = size >> pool->min_alloc_order;
	int nbytes = sizeof(struct gen_pool_chunk) +
				BITS_TO_LONGS(nbits) * sizeof(long);

	chunk = kzalloc_node(nbytes, GFP_KERNEL, nid);
	if (unlikely(chunk == NULL))
		return -ENOMEM;

	chunk->phys_addr = phys;
	chunk->start_addr = virt;
	chunk->end_addr = virt + size - 1;
	atomic_set(&chunk->avail, size);

	spin_lock(&pool->lock);
	list_add_rcu(&chunk->next_chunk, &pool->chunks);
	spin_unlock(&pool->lock);

	return 0;
}
EXPORT_SYMBOL(gen_pool_add_virt);

/**
 * gen_pool_virt_to_phys - return the physical address of memory
 * @pool: pool to allocate from
 * @addr: starting address of memory
 *
 * Returns the physical address on success, or -1 on error.
 */
phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr)
{
	struct gen_pool_chunk *chunk;
	phys_addr_t paddr = -1;

	rcu_read_lock();
	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
		if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
			paddr = chunk->phys_addr + (addr - chunk->start_addr);
			break;
		}
	}
	rcu_read_unlock();

	return paddr;
}
EXPORT_SYMBOL(gen_pool_virt_to_phys);

/**
 * gen_pool_destroy - destroy a special memory pool
 * @pool: pool to destroy
 *
 * Destroy the specified special memory pool. Verifies that there are no
 * outstanding allocations.
 */
void gen_pool_destroy(struct gen_pool *pool)
{
	struct list_head *_chunk, *_next_chunk;
	struct gen_pool_chunk *chunk;
	int order = pool->min_alloc_order;
	int bit, end_bit;

	list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {
		chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
		list_del(&chunk->next_chunk);

		end_bit = chunk_size(chunk) >> order;
		bit = find_next_bit(chunk->bits, end_bit, 0);
		BUG_ON(bit < end_bit);

		kfree(chunk);
	}
	kfree_const(pool->name);
	kfree(pool);
}
EXPORT_SYMBOL(gen_pool_destroy);

/**
 * gen_pool_alloc - allocate special memory from the pool
 * @pool: pool to allocate from
 * @size: number of bytes to allocate from the pool
 *
 * Allocate the requested number of bytes from the specified pool.
 * Uses the pool allocation function (with first-fit algorithm by default).
 * Can not be used in NMI handler on architectures without
 * NMI-safe cmpxchg implementation.
 */
unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
{
	return gen_pool_alloc_algo(pool, size, pool->algo, pool->data);
}
EXPORT_SYMBOL(gen_pool_alloc);

/**
 * gen_pool_alloc_algo - allocate special memory from the pool
 * @pool: pool to allocate from
 * @size: number of bytes to allocate from the pool
 * @algo: algorithm passed from caller
 * @data: data passed to algorithm
 *
 * Allocate the requested number of bytes from the specified pool.
 * Uses the pool allocation function (with first-fit algorithm by default).
 * Can not be used in NMI handler on architectures without
 * NMI-safe cmpxchg implementation.
 */
unsigned long gen_pool_alloc_algo(struct gen_pool *pool, size_t size,
		genpool_algo_t algo, void *data)
{
	struct gen_pool_chunk *chunk;
	unsigned long addr = 0;
	int order = pool->min_alloc_order;
	int nbits, start_bit, end_bit, remain;

#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
	BUG_ON(in_nmi());
#endif

	if (size == 0)
		return 0;

	nbits = (size + (1UL << order) - 1) >> order;
	rcu_read_lock();
	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
		if (size > atomic_read(&chunk->avail))
			continue;

		start_bit = 0;
		end_bit = chunk_size(chunk) >> order;
retry:
		start_bit = algo(chunk->bits, end_bit, start_bit,
				 nbits, data, pool);
		if (start_bit >= end_bit)
			continue;
		remain = bitmap_set_ll(chunk->bits, start_bit, nbits);
		if (remain) {
			remain = bitmap_clear_ll(chunk->bits, start_bit,
						 nbits - remain);
			BUG_ON(remain);
			goto retry;
		}

		addr = chunk->start_addr + ((unsigned long)start_bit << order);
		size = nbits << order;
		atomic_sub(size, &chunk->avail);
		break;
	}
	rcu_read_unlock();
	return addr;
}
EXPORT_SYMBOL(gen_pool_alloc_algo);

/**
 * gen_pool_dma_alloc - allocate special memory from the pool for DMA usage
 * @pool: pool to allocate from
 * @size: number of bytes to allocate from the pool
 * @dma: dma-view physical address return value.  Use NULL if unneeded.
 *
 * Allocate the requested number of bytes from the specified pool.
 * Uses the pool allocation function (with first-fit algorithm by default).
 * Can not be used in NMI handler on architectures without
 * NMI-safe cmpxchg implementation.
 */
void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
{
	unsigned long vaddr;

	if (!pool)
		return NULL;

	vaddr = gen_pool_alloc(pool, size);
	if (!vaddr)
		return NULL;

	if (dma)
		*dma = gen_pool_virt_to_phys(pool, vaddr);

	return (void *)vaddr;
}
EXPORT_SYMBOL(gen_pool_dma_alloc);

/**
 * gen_pool_free - free allocated special memory back to the pool
 * @pool: pool to free to
 * @addr: starting address of memory to free back to pool
 * @size: size in bytes of memory to free
 *
 * Free previously allocated special memory back to the specified
 * pool.  Can not be used in NMI handler on architectures without
 * NMI-safe cmpxchg implementation.
 */
void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
{
	struct gen_pool_chunk *chunk;
	int order = pool->min_alloc_order;
	int start_bit, nbits, remain;

#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
	BUG_ON(in_nmi());
#endif

	nbits = (size + (1UL << order) - 1) >> order;
	rcu_read_lock();
	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
		if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
			BUG_ON(addr + size - 1 > chunk->end_addr);
			start_bit = (addr - chunk->start_addr) >> order;
			remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);
			BUG_ON(remain);
			size = nbits << order;
			atomic_add(size, &chunk->avail);
			rcu_read_unlock();
			return;
		}
	}
	rcu_read_unlock();
	BUG();
}
EXPORT_SYMBOL(gen_pool_free);

/**
 * gen_pool_for_each_chunk - call func for every chunk of generic memory pool
 * @pool:	the generic memory pool
 * @func:	func to call
 * @data:	additional data used by @func
 *
 * Call @func for every chunk of generic memory pool.  The @func is
 * called with rcu_read_lock held.
 */
void gen_pool_for_each_chunk(struct gen_pool *pool,
	void (*func)(struct gen_pool *pool, struct gen_pool_chunk *chunk, void *data),
	void *data)
{
	struct gen_pool_chunk *chunk;

	rcu_read_lock();
	list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk)
		func(pool, chunk, data);
	rcu_read_unlock();
}
EXPORT_SYMBOL(gen_pool_for_each_chunk);

/**
 * addr_in_gen_pool - checks if an address falls within the range of a pool
 * @pool:	the generic memory pool
 * @start:	start address
 * @size:	size of the region
 *
 * Check if the range of addresses falls within the specified pool. Returns
 * true if the entire range is contained in the pool and false otherwise.
 */
bool addr_in_gen_pool(struct gen_pool *pool, unsigned long start,
			size_t size)
{
	bool found = false;
	unsigned long end = start + size - 1;
	struct gen_pool_chunk *chunk;

	rcu_read_lock();
	list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk) {
		if (start >= chunk->start_addr && start <= chunk->end_addr) {
			if (end <= chunk->end_addr) {
				found = true;
				break;
			}
		}
	}
	rcu_read_unlock();
	return found;
}

/**
 * gen_pool_avail - get available free space of the pool
 * @pool: pool to get available free space
 *
 * Return available free space of the specified pool.
 */
size_t gen_pool_avail(struct gen_pool *pool)
{
	struct gen_pool_chunk *chunk;
	size_t avail = 0;

	rcu_read_lock();
	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
		avail += atomic_read(&chunk->avail);
	rcu_read_unlock();
	return avail;
}
EXPORT_SYMBOL_GPL(gen_pool_avail);

/**
 * gen_pool_size - get size in bytes of memory managed by the pool
 * @pool: pool to get size
 *
 * Return size in bytes of memory managed by the pool.
 */
size_t gen_pool_size(struct gen_pool *pool)
{
	struct gen_pool_chunk *chunk;
	size_t size = 0;

	rcu_read_lock();
	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
		size += chunk_size(chunk);
	rcu_read_unlock();
	return size;
}
EXPORT_SYMBOL_GPL(gen_pool_size);

/**
 * gen_pool_set_algo - set the allocation algorithm
 * @pool: pool to change allocation algorithm
 * @algo: custom algorithm function
 * @data: additional data used by @algo
 *
 * Call @algo for each memory allocation in the pool.
 * If @algo is NULL use gen_pool_first_fit as default
 * memory allocation function.
 */
void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo, void *data)
{
	rcu_read_lock();

	pool->algo = algo;
	if (!pool->algo)
		pool->algo = gen_pool_first_fit;

	pool->data = data;

	rcu_read_unlock();
}
EXPORT_SYMBOL(gen_pool_set_algo);

/**
 * gen_pool_first_fit - find the first available region
 * of memory matching the size requirement (no alignment constraint)
 * @map: The address to base the search on
 * @size: The bitmap size in bits
 * @start: The bitnumber to start searching at
 * @nr: The number of zeroed bits we're looking for
 * @data: additional data - unused
 * @pool: pool to find the fit region memory from
 */
unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
		unsigned long start, unsigned int nr, void *data,
		struct gen_pool *pool)
{
	return bitmap_find_next_zero_area(map, size, start, nr, 0);
}
EXPORT_SYMBOL(gen_pool_first_fit);

/**
 * gen_pool_first_fit_align - find the first available region
 * of memory matching the size requirement (alignment constraint)
 * @map: The address to base the search on
 * @size: The bitmap size in bits
 * @start: The bitnumber to start searching at
 * @nr: The number of zeroed bits we're looking for
 * @data: data for alignment
 * @pool: pool to get order from
 */
unsigned long gen_pool_first_fit_align(unsigned long *map, unsigned long size,
		unsigned long start, unsigned int nr, void *data,
		struct gen_pool *pool)
{
	struct genpool_data_align *alignment;
	unsigned long align_mask;
	int order;

	alignment = data;
	order = pool->min_alloc_order;
	align_mask = ((alignment->align + (1UL << order) - 1) >> order) - 1;
	return bitmap_find_next_zero_area(map, size, start, nr, align_mask);
}
EXPORT_SYMBOL(gen_pool_first_fit_align);

/**
 * gen_pool_fixed_alloc - reserve a specific region
 * @map: The address to base the search on
 * @size: The bitmap size in bits
 * @start: The bitnumber to start searching at
 * @nr: The number of zeroed bits we're looking for
 * @data: data for alignment
 * @pool: pool to get order from
 */
unsigned long gen_pool_fixed_alloc(unsigned long *map, unsigned long size,
		unsigned long start, unsigned int nr, void *data,
		struct gen_pool *pool)
{
	struct genpool_data_fixed *fixed_data;
	int order;
	unsigned long offset_bit;
	unsigned long start_bit;

	fixed_data = data;
	order = pool->min_alloc_order;
	offset_bit = fixed_data->offset >> order;
	if (WARN_ON(fixed_data->offset & ((1UL << order) - 1)))
		return size;

	start_bit = bitmap_find_next_zero_area(map, size,
			start + offset_bit, nr, 0);
	if (start_bit != offset_bit)
		start_bit = size;
	return start_bit;
}
EXPORT_SYMBOL(gen_pool_fixed_alloc);

/**
 * gen_pool_first_fit_order_align - find the first available region
 * of memory matching the size requirement. The region will be aligned
 * to the order of the size specified.
 * @map: The address to base the search on
 * @size: The bitmap size in bits
 * @start: The bitnumber to start searching at
 * @nr: The number of zeroed bits we're looking for
 * @data: additional data - unused
 * @pool: pool to find the fit region memory from
 */
unsigned long gen_pool_first_fit_order_align(unsigned long *map,
		unsigned long size, unsigned long start,
		unsigned int nr, void *data, struct gen_pool *pool)
{
	unsigned long align_mask = roundup_pow_of_two(nr) - 1;

	return bitmap_find_next_zero_area(map, size, start, nr, align_mask);
}
EXPORT_SYMBOL(gen_pool_first_fit_order_align);

/**
 * gen_pool_best_fit - find the best fitting region of memory
 * macthing the size requirement (no alignment constraint)
 * @map: The address to base the search on
 * @size: The bitmap size in bits
 * @start: The bitnumber to start searching at
 * @nr: The number of zeroed bits we're looking for
 * @data: additional data - unused
 * @pool: pool to find the fit region memory from
 *
 * Iterate over the bitmap to find the smallest free region
 * which we can allocate the memory.
 */
unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
		unsigned long start, unsigned int nr, void *data,
		struct gen_pool *pool)
{
	unsigned long start_bit = size;
	unsigned long len = size + 1;
	unsigned long index;

	index = bitmap_find_next_zero_area(map, size, start, nr, 0);

	while (index < size) {
		int next_bit = find_next_bit(map, size, index + nr);
		if ((next_bit - index) < len) {
			len = next_bit - index;
			start_bit = index;
			if (len == nr)
				return start_bit;
		}
		index = bitmap_find_next_zero_area(map, size,
						   next_bit + 1, nr, 0);
	}

	return start_bit;
}
EXPORT_SYMBOL(gen_pool_best_fit);

static void devm_gen_pool_release(struct device *dev, void *res)
{
	gen_pool_destroy(*(struct gen_pool **)res);
}

static int devm_gen_pool_match(struct device *dev, void *res, void *data)
{
	struct gen_pool **p = res;

	/* NULL data matches only a pool without an assigned name */
	if (!data && !(*p)->name)
		return 1;

	if (!data || !(*p)->name)
		return 0;

	return !strcmp((*p)->name, data);
}

/**
 * gen_pool_get - Obtain the gen_pool (if any) for a device
 * @dev: device to retrieve the gen_pool from
 * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
 *
 * Returns the gen_pool for the device if one is present, or NULL.
 */
struct gen_pool *gen_pool_get(struct device *dev, const char *name)
{
	struct gen_pool **p;

	p = devres_find(dev, devm_gen_pool_release, devm_gen_pool_match,
			(void *)name);
	if (!p)
		return NULL;
	return *p;
}
EXPORT_SYMBOL_GPL(gen_pool_get);

/**
 * devm_gen_pool_create - managed gen_pool_create
 * @dev: device that provides the gen_pool
 * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
 * @nid: node selector for allocated gen_pool, %NUMA_NO_NODE for all nodes
 * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
 *
 * Create a new special memory pool that can be used to manage special purpose
 * memory not managed by the regular kmalloc/kfree interface. The pool will be
 * automatically destroyed by the device management code.
 */
struct gen_pool *devm_gen_pool_create(struct device *dev, int min_alloc_order,
				      int nid, const char *name)
{
	struct gen_pool **ptr, *pool;
	const char *pool_name = NULL;

	/* Check that genpool to be created is uniquely addressed on device */
	if (gen_pool_get(dev, name))
		return ERR_PTR(-EINVAL);

	if (name) {
		pool_name = kstrdup_const(name, GFP_KERNEL);
		if (!pool_name)
			return ERR_PTR(-ENOMEM);
	}

	ptr = devres_alloc(devm_gen_pool_release, sizeof(*ptr), GFP_KERNEL);
	if (!ptr)
		goto free_pool_name;

	pool = gen_pool_create(min_alloc_order, nid);
	if (!pool)
		goto free_devres;

	*ptr = pool;
	pool->name = pool_name;
	devres_add(dev, ptr);

	return pool;

free_devres:
	devres_free(ptr);
free_pool_name:
	kfree_const(pool_name);

	return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL(devm_gen_pool_create);

#ifdef CONFIG_OF
/**
 * of_gen_pool_get - find a pool by phandle property
 * @np: device node
 * @propname: property name containing phandle(s)
 * @index: index into the phandle array
 *
 * Returns the pool that contains the chunk starting at the physical
 * address of the device tree node pointed at by the phandle property,
 * or NULL if not found.
 */
struct gen_pool *of_gen_pool_get(struct device_node *np,
	const char *propname, int index)
{
	struct platform_device *pdev;
	struct device_node *np_pool, *parent;
	const char *name = NULL;
	struct gen_pool *pool = NULL;

	np_pool = of_parse_phandle(np, propname, index);
	if (!np_pool)
		return NULL;

	pdev = of_find_device_by_node(np_pool);
	if (!pdev) {
		/* Check if named gen_pool is created by parent node device */
		parent = of_get_parent(np_pool);
		pdev = of_find_device_by_node(parent);
		of_node_put(parent);

		of_property_read_string(np_pool, "label", &name);
		if (!name)
			name = np_pool->name;
	}
	if (pdev)
		pool = gen_pool_get(&pdev->dev, name);
	of_node_put(np_pool);

	return pool;
}
EXPORT_SYMBOL_GPL(of_gen_pool_get);
#endif /* CONFIG_OF */