genalloc.c 21.6 KB
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_long_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_long_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_long_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_long_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_long_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 */