lib/genalloc.c

   1 /*
   2  * Basic general purpose allocator for managing special purpose
   3  * memory, for example, memory that is not managed by the regular
   4  * kmalloc/kfree interface.  Uses for this includes on-device special
   5  * memory, uncached memory etc.
   6  *
   7  * It is safe to use the allocator in NMI handlers and other special
   8  * unblockable contexts that could otherwise deadlock on locks.  This
   9  * is implemented by using atomic operations and retries on any
  10  * conflicts.  The disadvantage is that there may be livelocks in
  11  * extreme cases.  For better scalability, one allocator can be used
  12  * for each CPU.
  13  *
  14  * The lockless operation only works if there is enough memory
  15  * available.  If new memory is added to the pool a lock has to be
  16  * still taken.  So any user relying on locklessness has to ensure
  17  * that sufficient memory is preallocated.
  18  *
  19  * The basic atomic operation of this allocator is cmpxchg on long.
  20  * On architectures that don't have NMI-safe cmpxchg implementation,
  21  * the allocator can NOT be used in NMI handler.  So code uses the
  22  * allocator in NMI handler should depend on
  23  * CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
  24  *
  25  * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>
  26  *
  27  * This source code is licensed under the GNU General Public License,
  28  * Version 2.  See the file COPYING for more details.
  29  */
  30
  31 #include <linux/slab.h>
  32 #include <linux/export.h>
  33 #include <linux/bitmap.h>
  34 #include <linux/rculist.h>
  35 #include <linux/interrupt.h>
  36 #include <linux/genalloc.h>
  37 #include <linux/of_device.h>
  38 #include <linux/vmalloc.h>
  39
  40 static inline size_t chunk_size(const struct gen_pool_chunk *chunk)
  41 {
  42         return chunk->end_addr - chunk->start_addr + 1;
  43 }
  44
  45 static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)
  46 {
  47         unsigned long val, nval;
  48
  49         nval = *addr;
  50         do {
  51                 val = nval;
  52                 if (val & mask_to_set)
  53                         return -EBUSY;
  54                 cpu_relax();
  55         } while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val);
  56
  57         return 0;
  58 }
  59
  60 static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear)
  61 {
  62         unsigned long val, nval;
  63
  64         nval = *addr;
  65         do {
  66                 val = nval;
  67                 if ((val & mask_to_clear) != mask_to_clear)
  68                         return -EBUSY;
  69                 cpu_relax();
  70         } while ((nval = cmpxchg(addr, val, val & ~mask_to_clear)) != val);
  71
  72         return 0;
  73 }
  74
  75 /*
  76  * bitmap_set_ll - set the specified number of bits at the specified position
  77  * @map: pointer to a bitmap
  78  * @start: a bit position in @map
  79  * @nr: number of bits to set
  80  *
  81  * Set @nr bits start from @start in @map lock-lessly. Several users
  82  * can set/clear the same bitmap simultaneously without lock. If two
  83  * users set the same bit, one user will return remain bits, otherwise
  84  * return 0.
  85  */
  86 static int bitmap_set_ll(unsigned long *map, int start, int nr)
  87 {
  88         unsigned long *p = map + BIT_WORD(start);
  89         const int size = start + nr;
  90         int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
  91         unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
  92
  93         while (nr - bits_to_set >= 0) {
  94                 if (set_bits_ll(p, mask_to_set))
  95                         return nr;
  96                 nr -= bits_to_set;
  97                 bits_to_set = BITS_PER_LONG;
  98                 mask_to_set = ~0UL;
  99                 p++;
 100         }
 101         if (nr) {
 102                 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
 103                 if (set_bits_ll(p, mask_to_set))
 104                         return nr;
 105         }
 106
 107         return 0;
 108 }
 109
 110 /*
 111  * bitmap_clear_ll - clear the specified number of bits at the specified position
 112  * @map: pointer to a bitmap
 113  * @start: a bit position in @map
 114  * @nr: number of bits to set
 115  *
 116  * Clear @nr bits start from @start in @map lock-lessly. Several users
 117  * can set/clear the same bitmap simultaneously without lock. If two
 118  * users clear the same bit, one user will return remain bits,
 119  * otherwise return 0.
 120  */
 121 static int bitmap_clear_ll(unsigned long *map, int start, int nr)
 122 {
 123         unsigned long *p = map + BIT_WORD(start);
 124         const int size = start + nr;
 125         int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
 126         unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
 127
 128         while (nr - bits_to_clear >= 0) {
 129                 if (clear_bits_ll(p, mask_to_clear))
 130                         return nr;
 131                 nr -= bits_to_clear;
 132                 bits_to_clear = BITS_PER_LONG;
 133                 mask_to_clear = ~0UL;
 134                 p++;
 135         }
 136         if (nr) {
 137                 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
 138                 if (clear_bits_ll(p, mask_to_clear))
 139                         return nr;
 140         }
 141
 142         return 0;
 143 }
 144
 145 /**
 146  * gen_pool_create - create a new special memory pool
 147  * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
 148  * @nid: node id of the node the pool structure should be allocated on, or -1
 149  *
 150  * Create a new special memory pool that can be used to manage special purpose
 151  * memory not managed by the regular kmalloc/kfree interface.
 152  */
 153 struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
 154 {
 155         struct gen_pool *pool;
 156
 157         pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);
 158         if (pool != NULL) {
 159                 spin_lock_init(&pool->lock);
 160                 INIT_LIST_HEAD(&pool->chunks);
 161                 pool->min_alloc_order = min_alloc_order;
 162                 pool->algo = gen_pool_first_fit;
 163                 pool->data = NULL;
 164                 pool->name = NULL;
 165         }
 166         return pool;
 167 }
 168 EXPORT_SYMBOL(gen_pool_create);
 169
 170 /**
 171  * gen_pool_add_virt - add a new chunk of special memory to the pool
 172  * @pool: pool to add new memory chunk to
 173  * @virt: virtual starting address of memory chunk to add to pool
 174  * @phys: physical starting address of memory chunk to add to pool
 175  * @size: size in bytes of the memory chunk to add to pool
 176  * @nid: node id of the node the chunk structure and bitmap should be
 177  *       allocated on, or -1
 178  *
 179  * Add a new chunk of special memory to the specified pool.
 180  *
 181  * Returns 0 on success or a -ve errno on failure.
 182  */
 183 int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt, phys_addr_t phys,
 184                  size_t size, int nid)
 185 {
 186         struct gen_pool_chunk *chunk;
 187         int nbits = size >> pool->min_alloc_order;
 188         int nbytes = sizeof(struct gen_pool_chunk) +
 189                                 BITS_TO_LONGS(nbits) * sizeof(long);
 190
 191         chunk = vzalloc_node(nbytes, nid);
 192         if (unlikely(chunk == NULL))
 193                 return -ENOMEM;
 194
 195         chunk->phys_addr = phys;
 196         chunk->start_addr = virt;
 197         chunk->end_addr = virt + size - 1;
 198         atomic_long_set(&chunk->avail, size);
 199
 200         spin_lock(&pool->lock);
 201         list_add_rcu(&chunk->next_chunk, &pool->chunks);
 202         spin_unlock(&pool->lock);
 203
 204         return 0;
 205 }
 206 EXPORT_SYMBOL(gen_pool_add_virt);
 207
 208 /**
 209  * gen_pool_virt_to_phys - return the physical address of memory
 210  * @pool: pool to allocate from
 211  * @addr: starting address of memory
 212  *
 213  * Returns the physical address on success, or -1 on error.
 214  */
 215 phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr)
 216 {
 217         struct gen_pool_chunk *chunk;
 218         phys_addr_t paddr = -1;
 219
 220         rcu_read_lock();
 221         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 222                 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
 223                         paddr = chunk->phys_addr + (addr - chunk->start_addr);
 224                         break;
 225                 }
 226         }
 227         rcu_read_unlock();
 228
 229         return paddr;
 230 }
 231 EXPORT_SYMBOL(gen_pool_virt_to_phys);
 232
 233 /**
 234  * gen_pool_destroy - destroy a special memory pool
 235  * @pool: pool to destroy
 236  *
 237  * Destroy the specified special memory pool. Verifies that there are no
 238  * outstanding allocations.
 239  */
 240 void gen_pool_destroy(struct gen_pool *pool)
 241 {
 242         struct list_head *_chunk, *_next_chunk;
 243         struct gen_pool_chunk *chunk;
 244         int order = pool->min_alloc_order;
 245         int bit, end_bit;
 246
 247         list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {
 248                 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
 249                 list_del(&chunk->next_chunk);
 250
 251                 end_bit = chunk_size(chunk) >> order;
 252                 bit = find_next_bit(chunk->bits, end_bit, 0);
 253                 BUG_ON(bit < end_bit);
 254
 255                 vfree(chunk);
 256         }
 257         kfree_const(pool->name);
 258         kfree(pool);
 259 }
 260 EXPORT_SYMBOL(gen_pool_destroy);
 261
 262 /**
 263  * gen_pool_alloc - allocate special memory from the pool
 264  * @pool: pool to allocate from
 265  * @size: number of bytes to allocate from the pool
 266  *
 267  * Allocate the requested number of bytes from the specified pool.
 268  * Uses the pool allocation function (with first-fit algorithm by default).
 269  * Can not be used in NMI handler on architectures without
 270  * NMI-safe cmpxchg implementation.
 271  */
 272 unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
 273 {
 274         return gen_pool_alloc_algo(pool, size, pool->algo, pool->data);
 275 }
 276 EXPORT_SYMBOL(gen_pool_alloc);
 277
 278 /**
 279  * gen_pool_alloc_algo - allocate special memory from the pool
 280  * @pool: pool to allocate from
 281  * @size: number of bytes to allocate from the pool
 282  * @algo: algorithm passed from caller
 283  * @data: data passed to algorithm
 284  *
 285  * Allocate the requested number of bytes from the specified pool.
 286  * Uses the pool allocation function (with first-fit algorithm by default).
 287  * Can not be used in NMI handler on architectures without
 288  * NMI-safe cmpxchg implementation.
 289  */
 290 unsigned long gen_pool_alloc_algo(struct gen_pool *pool, size_t size,
 291                 genpool_algo_t algo, void *data)
 292 {
 293         struct gen_pool_chunk *chunk;
 294         unsigned long addr = 0;
 295         int order = pool->min_alloc_order;
 296         int nbits, start_bit, end_bit, remain;
 297
 298 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
 299         BUG_ON(in_nmi());
 300 #endif
 301
 302         if (size == 0)
 303                 return 0;
 304
 305         nbits = (size + (1UL << order) - 1) >> order;
 306         rcu_read_lock();
 307         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 308                 if (size > atomic_long_read(&chunk->avail))
 309                         continue;
 310
 311                 start_bit = 0;
 312                 end_bit = chunk_size(chunk) >> order;
 313 retry:
 314                 start_bit = algo(chunk->bits, end_bit, start_bit,
 315                                  nbits, data, pool, chunk->start_addr);
 316                 if (start_bit >= end_bit)
 317                         continue;
 318                 remain = bitmap_set_ll(chunk->bits, start_bit, nbits);
 319                 if (remain) {
 320                         remain = bitmap_clear_ll(chunk->bits, start_bit,
 321                                                  nbits - remain);
 322                         BUG_ON(remain);
 323                         goto retry;
 324                 }
 325
 326                 addr = chunk->start_addr + ((unsigned long)start_bit << order);
 327                 size = nbits << order;
 328                 atomic_long_sub(size, &chunk->avail);
 329                 break;
 330         }
 331         rcu_read_unlock();
 332         return addr;
 333 }
 334 EXPORT_SYMBOL(gen_pool_alloc_algo);
 335
 336 /**
 337  * gen_pool_dma_alloc - allocate special memory from the pool for DMA usage
 338  * @pool: pool to allocate from
 339  * @size: number of bytes to allocate from the pool
 340  * @dma: dma-view physical address return value.  Use NULL if unneeded.
 341  *
 342  * Allocate the requested number of bytes from the specified pool.
 343  * Uses the pool allocation function (with first-fit algorithm by default).
 344  * Can not be used in NMI handler on architectures without
 345  * NMI-safe cmpxchg implementation.
 346  */
 347 void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
 348 {
 349         unsigned long vaddr;
 350
 351         if (!pool)
 352                 return NULL;
 353
 354         vaddr = gen_pool_alloc(pool, size);
 355         if (!vaddr)
 356                 return NULL;
 357
 358         if (dma)
 359                 *dma = gen_pool_virt_to_phys(pool, vaddr);
 360
 361         return (void *)vaddr;
 362 }
 363 EXPORT_SYMBOL(gen_pool_dma_alloc);
 364
 365 /**
 366  * gen_pool_free - free allocated special memory back to the pool
 367  * @pool: pool to free to
 368  * @addr: starting address of memory to free back to pool
 369  * @size: size in bytes of memory to free
 370  *
 371  * Free previously allocated special memory back to the specified
 372  * pool.  Can not be used in NMI handler on architectures without
 373  * NMI-safe cmpxchg implementation.
 374  */
 375 void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
 376 {
 377         struct gen_pool_chunk *chunk;
 378         int order = pool->min_alloc_order;
 379         int start_bit, nbits, remain;
 380
 381 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
 382         BUG_ON(in_nmi());
 383 #endif
 384
 385         nbits = (size + (1UL << order) - 1) >> order;
 386         rcu_read_lock();
 387         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 388                 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
 389                         BUG_ON(addr + size - 1 > chunk->end_addr);
 390                         start_bit = (addr - chunk->start_addr) >> order;
 391                         remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);
 392                         BUG_ON(remain);
 393                         size = nbits << order;
 394                         atomic_long_add(size, &chunk->avail);
 395                         rcu_read_unlock();
 396                         return;
 397                 }
 398         }
 399         rcu_read_unlock();
 400         BUG();
 401 }
 402 EXPORT_SYMBOL(gen_pool_free);
 403
 404 /**
 405  * gen_pool_for_each_chunk - call func for every chunk of generic memory pool
 406  * @pool:       the generic memory pool
 407  * @func:       func to call
 408  * @data:       additional data used by @func
 409  *
 410  * Call @func for every chunk of generic memory pool.  The @func is
 411  * called with rcu_read_lock held.
 412  */
 413 void gen_pool_for_each_chunk(struct gen_pool *pool,
 414         void (*func)(struct gen_pool *pool, struct gen_pool_chunk *chunk, void *data),
 415         void *data)
 416 {
 417         struct gen_pool_chunk *chunk;
 418
 419         rcu_read_lock();
 420         list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk)
 421                 func(pool, chunk, data);
 422         rcu_read_unlock();
 423 }
 424 EXPORT_SYMBOL(gen_pool_for_each_chunk);
 425
 426 /**
 427  * addr_in_gen_pool - checks if an address falls within the range of a pool
 428  * @pool:       the generic memory pool
 429  * @start:      start address
 430  * @size:       size of the region
 431  *
 432  * Check if the range of addresses falls within the specified pool. Returns
 433  * true if the entire range is contained in the pool and false otherwise.
 434  */
 435 bool addr_in_gen_pool(struct gen_pool *pool, unsigned long start,
 436                         size_t size)
 437 {
 438         bool found = false;
 439         unsigned long end = start + size - 1;
 440         struct gen_pool_chunk *chunk;
 441
 442         rcu_read_lock();
 443         list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk) {
 444                 if (start >= chunk->start_addr && start <= chunk->end_addr) {
 445                         if (end <= chunk->end_addr) {
 446                                 found = true;
 447                                 break;
 448                         }
 449                 }
 450         }
 451         rcu_read_unlock();
 452         return found;
 453 }
 454
 455 /**
 456  * gen_pool_avail - get available free space of the pool
 457  * @pool: pool to get available free space
 458  *
 459  * Return available free space of the specified pool.
 460  */
 461 size_t gen_pool_avail(struct gen_pool *pool)
 462 {
 463         struct gen_pool_chunk *chunk;
 464         size_t avail = 0;
 465
 466         rcu_read_lock();
 467         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
 468                 avail += atomic_long_read(&chunk->avail);
 469         rcu_read_unlock();
 470         return avail;
 471 }
 472 EXPORT_SYMBOL_GPL(gen_pool_avail);
 473
 474 /**
 475  * gen_pool_size - get size in bytes of memory managed by the pool
 476  * @pool: pool to get size
 477  *
 478  * Return size in bytes of memory managed by the pool.
 479  */
 480 size_t gen_pool_size(struct gen_pool *pool)
 481 {
 482         struct gen_pool_chunk *chunk;
 483         size_t size = 0;
 484
 485         rcu_read_lock();
 486         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
 487                 size += chunk_size(chunk);
 488         rcu_read_unlock();
 489         return size;
 490 }
 491 EXPORT_SYMBOL_GPL(gen_pool_size);
 492
 493 /**
 494  * gen_pool_set_algo - set the allocation algorithm
 495  * @pool: pool to change allocation algorithm
 496  * @algo: custom algorithm function
 497  * @data: additional data used by @algo
 498  *
 499  * Call @algo for each memory allocation in the pool.
 500  * If @algo is NULL use gen_pool_first_fit as default
 501  * memory allocation function.
 502  */
 503 void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo, void *data)
 504 {
 505         rcu_read_lock();
 506
 507         pool->algo = algo;
 508         if (!pool->algo)
 509                 pool->algo = gen_pool_first_fit;
 510
 511         pool->data = data;
 512
 513         rcu_read_unlock();
 514 }
 515 EXPORT_SYMBOL(gen_pool_set_algo);
 516
 517 /**
 518  * gen_pool_first_fit - find the first available region
 519  * of memory matching the size requirement (no alignment constraint)
 520  * @map: The address to base the search on
 521  * @size: The bitmap size in bits
 522  * @start: The bitnumber to start searching at
 523  * @nr: The number of zeroed bits we're looking for
 524  * @data: additional data - unused
 525  * @pool: pool to find the fit region memory from
 526  */
 527 unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
 528                 unsigned long start, unsigned int nr, void *data,
 529                 struct gen_pool *pool, unsigned long start_addr)
 530 {
 531         return bitmap_find_next_zero_area(map, size, start, nr, 0);
 532 }
 533 EXPORT_SYMBOL(gen_pool_first_fit);
 534
 535 /**
 536  * gen_pool_first_fit_align - find the first available region
 537  * of memory matching the size requirement (alignment constraint)
 538  * @map: The address to base the search on
 539  * @size: The bitmap size in bits
 540  * @start: The bitnumber to start searching at
 541  * @nr: The number of zeroed bits we're looking for
 542  * @data: data for alignment
 543  * @pool: pool to get order from
 544  */
 545 unsigned long gen_pool_first_fit_align(unsigned long *map, unsigned long size,
 546                 unsigned long start, unsigned int nr, void *data,
 547                 struct gen_pool *pool, unsigned long start_addr)
 548 {
 549         struct genpool_data_align *alignment;
 550         unsigned long align_mask, align_off;
 551         int order;
 552
 553         alignment = data;
 554         order = pool->min_alloc_order;
 555         align_mask = ((alignment->align + (1UL << order) - 1) >> order) - 1;
 556         align_off = (start_addr & (alignment->align - 1)) >> order;
 557
 558         return bitmap_find_next_zero_area_off(map, size, start, nr,
 559                                               align_mask, align_off);
 560 }
 561 EXPORT_SYMBOL(gen_pool_first_fit_align);
 562
 563 /**
 564  * gen_pool_fixed_alloc - reserve a specific region
 565  * @map: The address to base the search on
 566  * @size: The bitmap size in bits
 567  * @start: The bitnumber to start searching at
 568  * @nr: The number of zeroed bits we're looking for
 569  * @data: data for alignment
 570  * @pool: pool to get order from
 571  */
 572 unsigned long gen_pool_fixed_alloc(unsigned long *map, unsigned long size,
 573                 unsigned long start, unsigned int nr, void *data,
 574                 struct gen_pool *pool, unsigned long start_addr)
 575 {
 576         struct genpool_data_fixed *fixed_data;
 577         int order;
 578         unsigned long offset_bit;
 579         unsigned long start_bit;
 580
 581         fixed_data = data;
 582         order = pool->min_alloc_order;
 583         offset_bit = fixed_data->offset >> order;
 584         if (WARN_ON(fixed_data->offset & ((1UL << order) - 1)))
 585                 return size;
 586
 587         start_bit = bitmap_find_next_zero_area(map, size,
 588                         start + offset_bit, nr, 0);
 589         if (start_bit != offset_bit)
 590                 start_bit = size;
 591         return start_bit;
 592 }
 593 EXPORT_SYMBOL(gen_pool_fixed_alloc);
 594
 595 /**
 596  * gen_pool_first_fit_order_align - find the first available region
 597  * of memory matching the size requirement. The region will be aligned
 598  * to the order of the size specified.
 599  * @map: The address to base the search on
 600  * @size: The bitmap size in bits
 601  * @start: The bitnumber to start searching at
 602  * @nr: The number of zeroed bits we're looking for
 603  * @data: additional data - unused
 604  * @pool: pool to find the fit region memory from
 605  */
 606 unsigned long gen_pool_first_fit_order_align(unsigned long *map,
 607                 unsigned long size, unsigned long start,
 608                 unsigned int nr, void *data, struct gen_pool *pool,
 609                 unsigned long start_addr)
 610 {
 611         unsigned long align_mask = roundup_pow_of_two(nr) - 1;
 612
 613         return bitmap_find_next_zero_area(map, size, start, nr, align_mask);
 614 }
 615 EXPORT_SYMBOL(gen_pool_first_fit_order_align);
 616
 617 /**
 618  * gen_pool_best_fit - find the best fitting region of memory
 619  * macthing the size requirement (no alignment constraint)
 620  * @map: The address to base the search on
 621  * @size: The bitmap size in bits
 622  * @start: The bitnumber to start searching at
 623  * @nr: The number of zeroed bits we're looking for
 624  * @data: additional data - unused
 625  * @pool: pool to find the fit region memory from
 626  *
 627  * Iterate over the bitmap to find the smallest free region
 628  * which we can allocate the memory.
 629  */
 630 unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
 631                 unsigned long start, unsigned int nr, void *data,
 632                 struct gen_pool *pool, unsigned long start_addr)
 633 {
 634         unsigned long start_bit = size;
 635         unsigned long len = size + 1;
 636         unsigned long index;
 637
 638         index = bitmap_find_next_zero_area(map, size, start, nr, 0);
 639
 640         while (index < size) {
 641                 int next_bit = find_next_bit(map, size, index + nr);
 642                 if ((next_bit - index) < len) {
 643                         len = next_bit - index;
 644                         start_bit = index;
 645                         if (len == nr)
 646                                 return start_bit;
 647                 }
 648                 index = bitmap_find_next_zero_area(map, size,
 649                                                    next_bit + 1, nr, 0);
 650         }
 651
 652         return start_bit;
 653 }
 654 EXPORT_SYMBOL(gen_pool_best_fit);
 655
 656 static void devm_gen_pool_release(struct device *dev, void *res)
 657 {
 658         gen_pool_destroy(*(struct gen_pool **)res);
 659 }
 660
 661 static int devm_gen_pool_match(struct device *dev, void *res, void *data)
 662 {
 663         struct gen_pool **p = res;
 664
 665         /* NULL data matches only a pool without an assigned name */
 666         if (!data && !(*p)->name)
 667                 return 1;
 668
 669         if (!data || !(*p)->name)
 670                 return 0;
 671
 672         return !strcmp((*p)->name, data);
 673 }
 674
 675 /**
 676  * gen_pool_get - Obtain the gen_pool (if any) for a device
 677  * @dev: device to retrieve the gen_pool from
 678  * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
 679  *
 680  * Returns the gen_pool for the device if one is present, or NULL.
 681  */
 682 struct gen_pool *gen_pool_get(struct device *dev, const char *name)
 683 {
 684         struct gen_pool **p;
 685
 686         p = devres_find(dev, devm_gen_pool_release, devm_gen_pool_match,
 687                         (void *)name);
 688         if (!p)
 689                 return NULL;
 690         return *p;
 691 }
 692 EXPORT_SYMBOL_GPL(gen_pool_get);
 693
 694 /**
 695  * devm_gen_pool_create - managed gen_pool_create
 696  * @dev: device that provides the gen_pool
 697  * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
 698  * @nid: node selector for allocated gen_pool, %NUMA_NO_NODE for all nodes
 699  * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
 700  *
 701  * Create a new special memory pool that can be used to manage special purpose
 702  * memory not managed by the regular kmalloc/kfree interface. The pool will be
 703  * automatically destroyed by the device management code.
 704  */
 705 struct gen_pool *devm_gen_pool_create(struct device *dev, int min_alloc_order,
 706                                       int nid, const char *name)
 707 {
 708         struct gen_pool **ptr, *pool;
 709         const char *pool_name = NULL;
 710
 711         /* Check that genpool to be created is uniquely addressed on device */
 712         if (gen_pool_get(dev, name))
 713                 return ERR_PTR(-EINVAL);
 714
 715         if (name) {
 716                 pool_name = kstrdup_const(name, GFP_KERNEL);
 717                 if (!pool_name)
 718                         return ERR_PTR(-ENOMEM);
 719         }
 720
 721         ptr = devres_alloc(devm_gen_pool_release, sizeof(*ptr), GFP_KERNEL);
 722         if (!ptr)
 723                 goto free_pool_name;
 724
 725         pool = gen_pool_create(min_alloc_order, nid);
 726         if (!pool)
 727                 goto free_devres;
 728
 729         *ptr = pool;
 730         pool->name = pool_name;
 731         devres_add(dev, ptr);
 732
 733         return pool;
 734
 735 free_devres:
 736         devres_free(ptr);
 737 free_pool_name:
 738         kfree_const(pool_name);
 739
 740         return ERR_PTR(-ENOMEM);
 741 }
 742 EXPORT_SYMBOL(devm_gen_pool_create);
 743
 744 #ifdef CONFIG_OF
 745 /**
 746  * of_gen_pool_get - find a pool by phandle property
 747  * @np: device node
 748  * @propname: property name containing phandle(s)
 749  * @index: index into the phandle array
 750  *
 751  * Returns the pool that contains the chunk starting at the physical
 752  * address of the device tree node pointed at by the phandle property,
 753  * or NULL if not found.
 754  */
 755 struct gen_pool *of_gen_pool_get(struct device_node *np,
 756         const char *propname, int index)
 757 {
 758         struct platform_device *pdev;
 759         struct device_node *np_pool, *parent;
 760         const char *name = NULL;
 761         struct gen_pool *pool = NULL;
 762
 763         np_pool = of_parse_phandle(np, propname, index);
 764         if (!np_pool)
 765                 return NULL;
 766
 767         pdev = of_find_device_by_node(np_pool);
 768         if (!pdev) {
 769                 /* Check if named gen_pool is created by parent node device */
 770                 parent = of_get_parent(np_pool);
 771                 pdev = of_find_device_by_node(parent);
 772                 of_node_put(parent);
 773
 774                 of_property_read_string(np_pool, "label", &name);
 775                 if (!name)
 776                         name = np_pool->name;
 777         }
 778         if (pdev)
 779                 pool = gen_pool_get(&pdev->dev, name);
 780         of_node_put(np_pool);
 781
 782         return pool;
 783 }
 784 EXPORT_SYMBOL_GPL(of_gen_pool_get);
 785 #endif /* CONFIG_OF */