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