lib/genalloc.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Basic general purpose allocator for managing special purpose
   4  * memory, for example, memory that is not managed by the regular
   5  * kmalloc/kfree interface.  Uses for this includes on-device special
   6  * memory, uncached memory etc.
   7  *
   8  * It is safe to use the allocator in NMI handlers and other special
   9  * unblockable contexts that could otherwise deadlock on locks.  This
  10  * is implemented by using atomic operations and retries on any
  11  * conflicts.  The disadvantage is that there may be livelocks in
  12  * extreme cases.  For better scalability, one allocator can be used
  13  * for each CPU.
  14  *
  15  * The lockless operation only works if there is enough memory
  16  * available.  If new memory is added to the pool a lock has to be
  17  * still taken.  So any user relying on locklessness has to ensure
  18  * that sufficient memory is preallocated.
  19  *
  20  * The basic atomic operation of this allocator is cmpxchg on long.
  21  * On architectures that don't have NMI-safe cmpxchg implementation,
  22  * the allocator can NOT be used in NMI handler.  So code uses the
  23  * allocator in NMI handler should depend on
  24  * CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
  25  *
  26  * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>
  27  */
  28
  29 #include <linux/slab.h>
  30 #include <linux/export.h>
  31 #include <linux/bitmap.h>
  32 #include <linux/rculist.h>
  33 #include <linux/interrupt.h>
  34 #include <linux/genalloc.h>
  35 #include <linux/of_device.h>
  36 #include <linux/vmalloc.h>
  37
  38 static inline size_t chunk_size(const struct gen_pool_chunk *chunk)
  39 {
  40         return chunk->end_addr - chunk->start_addr + 1;
  41 }
  42
  43 static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)
  44 {
  45         unsigned long val, nval;
  46
  47         nval = *addr;
  48         do {
  49                 val = nval;
  50                 if (val & mask_to_set)
  51                         return -EBUSY;
  52                 cpu_relax();
  53         } while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val);
  54
  55         return 0;
  56 }
  57
  58 static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear)
  59 {
  60         unsigned long val, nval;
  61
  62         nval = *addr;
  63         do {
  64                 val = nval;
  65                 if ((val & mask_to_clear) != mask_to_clear)
  66                         return -EBUSY;
  67                 cpu_relax();
  68         } while ((nval = cmpxchg(addr, val, val & ~mask_to_clear)) != val);
  69
  70         return 0;
  71 }
  72
  73 /*
  74  * bitmap_set_ll - set the specified number of bits at the specified position
  75  * @map: pointer to a bitmap
  76  * @start: a bit position in @map
  77  * @nr: number of bits to set
  78  *
  79  * Set @nr bits start from @start in @map lock-lessly. Several users
  80  * can set/clear the same bitmap simultaneously without lock. If two
  81  * users set the same bit, one user will return remain bits, otherwise
  82  * return 0.
  83  */
  84 static int bitmap_set_ll(unsigned long *map, int start, int nr)
  85 {
  86         unsigned long *p = map + BIT_WORD(start);
  87         const int size = start + nr;
  88         int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
  89         unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
  90
  91         while (nr - bits_to_set >= 0) {
  92                 if (set_bits_ll(p, mask_to_set))
  93                         return nr;
  94                 nr -= bits_to_set;
  95                 bits_to_set = BITS_PER_LONG;
  96                 mask_to_set = ~0UL;
  97                 p++;
  98         }
  99         if (nr) {
 100                 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
 101                 if (set_bits_ll(p, mask_to_set))
 102                         return nr;
 103         }
 104
 105         return 0;
 106 }
 107
 108 /*
 109  * bitmap_clear_ll - clear the specified number of bits at the specified position
 110  * @map: pointer to a bitmap
 111  * @start: a bit position in @map
 112  * @nr: number of bits to set
 113  *
 114  * Clear @nr bits start from @start in @map lock-lessly. Several users
 115  * can set/clear the same bitmap simultaneously without lock. If two
 116  * users clear the same bit, one user will return remain bits,
 117  * otherwise return 0.
 118  */
 119 static int bitmap_clear_ll(unsigned long *map, int start, int nr)
 120 {
 121         unsigned long *p = map + BIT_WORD(start);
 122         const int size = start + nr;
 123         int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
 124         unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
 125
 126         while (nr - bits_to_clear >= 0) {
 127                 if (clear_bits_ll(p, mask_to_clear))
 128                         return nr;
 129                 nr -= bits_to_clear;
 130                 bits_to_clear = BITS_PER_LONG;
 131                 mask_to_clear = ~0UL;
 132                 p++;
 133         }
 134         if (nr) {
 135                 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
 136                 if (clear_bits_ll(p, mask_to_clear))
 137                         return nr;
 138         }
 139
 140         return 0;
 141 }
 142
 143 /**
 144  * gen_pool_create - create a new special memory pool
 145  * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
 146  * @nid: node id of the node the pool structure should be allocated on, or -1
 147  *
 148  * Create a new special memory pool that can be used to manage special purpose
 149  * memory not managed by the regular kmalloc/kfree interface.
 150  */
 151 struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
 152 {
 153         struct gen_pool *pool;
 154
 155         pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);
 156         if (pool != NULL) {
 157                 spin_lock_init(&pool->lock);
 158                 INIT_LIST_HEAD(&pool->chunks);
 159                 pool->min_alloc_order = min_alloc_order;
 160                 pool->algo = gen_pool_first_fit;
 161                 pool->data = NULL;
 162                 pool->name = NULL;
 163         }
 164         return pool;
 165 }
 166 EXPORT_SYMBOL(gen_pool_create);
 167
 168 /**
 169  * gen_pool_add_owner- add a new chunk of special memory to the pool
 170  * @pool: pool to add new memory chunk to
 171  * @virt: virtual starting address of memory chunk to add to pool
 172  * @phys: physical starting address of memory chunk to add to pool
 173  * @size: size in bytes of the memory chunk to add to pool
 174  * @nid: node id of the node the chunk structure and bitmap should be
 175  *       allocated on, or -1
 176  * @owner: private data the publisher would like to recall at alloc time
 177  *
 178  * Add a new chunk of special memory to the specified pool.
 179  *
 180  * Returns 0 on success or a -ve errno on failure.
 181  */
 182 int gen_pool_add_owner(struct gen_pool *pool, unsigned long virt, phys_addr_t phys,
 183                  size_t size, int nid, void *owner)
 184 {
 185         struct gen_pool_chunk *chunk;
 186         int nbits = size >> pool->min_alloc_order;
 187         int nbytes = sizeof(struct gen_pool_chunk) +
 188                                 BITS_TO_LONGS(nbits) * sizeof(long);
 189
 190         chunk = vzalloc_node(nbytes, nid);
 191         if (unlikely(chunk == NULL))
 192                 return -ENOMEM;
 193
 194         chunk->phys_addr = phys;
 195         chunk->start_addr = virt;
 196         chunk->end_addr = virt + size - 1;
 197         chunk->owner = owner;
 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_owner);
 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_algo_owner - allocate special memory from the pool
 264  * @pool: pool to allocate from
 265  * @size: number of bytes to allocate from the pool
 266  * @algo: algorithm passed from caller
 267  * @data: data passed to algorithm
 268  * @owner: optionally retrieve the chunk owner
 269  *
 270  * Allocate the requested number of bytes from the specified pool.
 271  * Uses the pool allocation function (with first-fit algorithm by default).
 272  * Can not be used in NMI handler on architectures without
 273  * NMI-safe cmpxchg implementation.
 274  */
 275 unsigned long gen_pool_alloc_algo_owner(struct gen_pool *pool, size_t size,
 276                 genpool_algo_t algo, void *data, void **owner)
 277 {
 278         struct gen_pool_chunk *chunk;
 279         unsigned long addr = 0;
 280         int order = pool->min_alloc_order;
 281         int nbits, start_bit, end_bit, remain;
 282
 283 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
 284         BUG_ON(in_nmi());
 285 #endif
 286
 287         if (owner)
 288                 *owner = NULL;
 289
 290         if (size == 0)
 291                 return 0;
 292
 293         nbits = (size + (1UL << order) - 1) >> order;
 294         rcu_read_lock();
 295         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 296                 if (size > atomic_long_read(&chunk->avail))
 297                         continue;
 298
 299                 start_bit = 0;
 300                 end_bit = chunk_size(chunk) >> order;
 301 retry:
 302                 start_bit = algo(chunk->bits, end_bit, start_bit,
 303                                  nbits, data, pool, chunk->start_addr);
 304                 if (start_bit >= end_bit)
 305                         continue;
 306                 remain = bitmap_set_ll(chunk->bits, start_bit, nbits);
 307                 if (remain) {
 308                         remain = bitmap_clear_ll(chunk->bits, start_bit,
 309                                                  nbits - remain);
 310                         BUG_ON(remain);
 311                         goto retry;
 312                 }
 313
 314                 addr = chunk->start_addr + ((unsigned long)start_bit << order);
 315                 size = nbits << order;
 316                 atomic_long_sub(size, &chunk->avail);
 317                 if (owner)
 318                         *owner = chunk->owner;
 319                 break;
 320         }
 321         rcu_read_unlock();
 322         return addr;
 323 }
 324 EXPORT_SYMBOL(gen_pool_alloc_algo_owner);
 325
 326 /**
 327  * gen_pool_dma_alloc - allocate special memory from the pool for DMA usage
 328  * @pool: pool to allocate from
 329  * @size: number of bytes to allocate from the pool
 330  * @dma: dma-view physical address return value.  Use NULL if unneeded.
 331  *
 332  * Allocate the requested number of bytes from the specified pool.
 333  * Uses the pool allocation function (with first-fit algorithm by default).
 334  * Can not be used in NMI handler on architectures without
 335  * NMI-safe cmpxchg implementation.
 336  */
 337 void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
 338 {
 339         unsigned long vaddr;
 340
 341         if (!pool)
 342                 return NULL;
 343
 344         vaddr = gen_pool_alloc(pool, size);
 345         if (!vaddr)
 346                 return NULL;
 347
 348         if (dma)
 349                 *dma = gen_pool_virt_to_phys(pool, vaddr);
 350
 351         return (void *)vaddr;
 352 }
 353 EXPORT_SYMBOL(gen_pool_dma_alloc);
 354
 355 /**
 356  * gen_pool_free - free allocated special memory back to the pool
 357  * @pool: pool to free to
 358  * @addr: starting address of memory to free back to pool
 359  * @size: size in bytes of memory to free
 360  * @owner: private data stashed at gen_pool_add() time
 361  *
 362  * Free previously allocated special memory back to the specified
 363  * pool.  Can not be used in NMI handler on architectures without
 364  * NMI-safe cmpxchg implementation.
 365  */
 366 void gen_pool_free_owner(struct gen_pool *pool, unsigned long addr, size_t size,
 367                 void **owner)
 368 {
 369         struct gen_pool_chunk *chunk;
 370         int order = pool->min_alloc_order;
 371         int start_bit, nbits, remain;
 372
 373 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
 374         BUG_ON(in_nmi());
 375 #endif
 376
 377         if (owner)
 378                 *owner = NULL;
 379
 380         nbits = (size + (1UL << order) - 1) >> order;
 381         rcu_read_lock();
 382         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 383                 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
 384                         BUG_ON(addr + size - 1 > chunk->end_addr);
 385                         start_bit = (addr - chunk->start_addr) >> order;
 386                         remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);
 387                         BUG_ON(remain);
 388                         size = nbits << order;
 389                         atomic_long_add(size, &chunk->avail);
 390                         if (owner)
 391                                 *owner = chunk->owner;
 392                         rcu_read_unlock();
 393                         return;
 394                 }
 395         }
 396         rcu_read_unlock();
 397         BUG();
 398 }
 399 EXPORT_SYMBOL(gen_pool_free_owner);
 400
 401 /**
 402  * gen_pool_for_each_chunk - call func for every chunk of generic memory pool
 403  * @pool:       the generic memory pool
 404  * @func:       func to call
 405  * @data:       additional data used by @func
 406  *
 407  * Call @func for every chunk of generic memory pool.  The @func is
 408  * called with rcu_read_lock held.
 409  */
 410 void gen_pool_for_each_chunk(struct gen_pool *pool,
 411         void (*func)(struct gen_pool *pool, struct gen_pool_chunk *chunk, void *data),
 412         void *data)
 413 {
 414         struct gen_pool_chunk *chunk;
 415
 416         rcu_read_lock();
 417         list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk)
 418                 func(pool, chunk, data);
 419         rcu_read_unlock();
 420 }
 421 EXPORT_SYMBOL(gen_pool_for_each_chunk);
 422
 423 /**
 424  * addr_in_gen_pool - checks if an address falls within the range of a pool
 425  * @pool:       the generic memory pool
 426  * @start:      start address
 427  * @size:       size of the region
 428  *
 429  * Check if the range of addresses falls within the specified pool. Returns
 430  * true if the entire range is contained in the pool and false otherwise.
 431  */
 432 bool addr_in_gen_pool(struct gen_pool *pool, unsigned long start,
 433                         size_t size)
 434 {
 435         bool found = false;
 436         unsigned long end = start + size - 1;
 437         struct gen_pool_chunk *chunk;
 438
 439         rcu_read_lock();
 440         list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk) {
 441                 if (start >= chunk->start_addr && start <= chunk->end_addr) {
 442                         if (end <= chunk->end_addr) {
 443                                 found = true;
 444                                 break;
 445                         }
 446                 }
 447         }
 448         rcu_read_unlock();
 449         return found;
 450 }
 451
 452 /**
 453  * gen_pool_avail - get available free space of the pool
 454  * @pool: pool to get available free space
 455  *
 456  * Return available free space of the specified pool.
 457  */
 458 size_t gen_pool_avail(struct gen_pool *pool)
 459 {
 460         struct gen_pool_chunk *chunk;
 461         size_t avail = 0;
 462
 463         rcu_read_lock();
 464         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
 465                 avail += atomic_long_read(&chunk->avail);
 466         rcu_read_unlock();
 467         return avail;
 468 }
 469 EXPORT_SYMBOL_GPL(gen_pool_avail);
 470
 471 /**
 472  * gen_pool_size - get size in bytes of memory managed by the pool
 473  * @pool: pool to get size
 474  *
 475  * Return size in bytes of memory managed by the pool.
 476  */
 477 size_t gen_pool_size(struct gen_pool *pool)
 478 {
 479         struct gen_pool_chunk *chunk;
 480         size_t size = 0;
 481
 482         rcu_read_lock();
 483         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
 484                 size += chunk_size(chunk);
 485         rcu_read_unlock();
 486         return size;
 487 }
 488 EXPORT_SYMBOL_GPL(gen_pool_size);
 489
 490 /**
 491  * gen_pool_set_algo - set the allocation algorithm
 492  * @pool: pool to change allocation algorithm
 493  * @algo: custom algorithm function
 494  * @data: additional data used by @algo
 495  *
 496  * Call @algo for each memory allocation in the pool.
 497  * If @algo is NULL use gen_pool_first_fit as default
 498  * memory allocation function.
 499  */
 500 void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo, void *data)
 501 {
 502         rcu_read_lock();
 503
 504         pool->algo = algo;
 505         if (!pool->algo)
 506                 pool->algo = gen_pool_first_fit;
 507
 508         pool->data = data;
 509
 510         rcu_read_unlock();
 511 }
 512 EXPORT_SYMBOL(gen_pool_set_algo);
 513
 514 /**
 515  * gen_pool_first_fit - find the first available region
 516  * of memory matching the size requirement (no alignment constraint)
 517  * @map: The address to base the search on
 518  * @size: The bitmap size in bits
 519  * @start: The bitnumber to start searching at
 520  * @nr: The number of zeroed bits we're looking for
 521  * @data: additional data - unused
 522  * @pool: pool to find the fit region memory from
 523  */
 524 unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
 525                 unsigned long start, unsigned int nr, void *data,
 526                 struct gen_pool *pool, unsigned long start_addr)
 527 {
 528         return bitmap_find_next_zero_area(map, size, start, nr, 0);
 529 }
 530 EXPORT_SYMBOL(gen_pool_first_fit);
 531
 532 /**
 533  * gen_pool_first_fit_align - find the first available region
 534  * of memory matching the size requirement (alignment constraint)
 535  * @map: The address to base the search on
 536  * @size: The bitmap size in bits
 537  * @start: The bitnumber to start searching at
 538  * @nr: The number of zeroed bits we're looking for
 539  * @data: data for alignment
 540  * @pool: pool to get order from
 541  */
 542 unsigned long gen_pool_first_fit_align(unsigned long *map, unsigned long size,
 543                 unsigned long start, unsigned int nr, void *data,
 544                 struct gen_pool *pool, unsigned long start_addr)
 545 {
 546         struct genpool_data_align *alignment;
 547         unsigned long align_mask, align_off;
 548         int order;
 549
 550         alignment = data;
 551         order = pool->min_alloc_order;
 552         align_mask = ((alignment->align + (1UL << order) - 1) >> order) - 1;
 553         align_off = (start_addr & (alignment->align - 1)) >> order;
 554
 555         return bitmap_find_next_zero_area_off(map, size, start, nr,
 556                                               align_mask, align_off);
 557 }
 558 EXPORT_SYMBOL(gen_pool_first_fit_align);
 559
 560 /**
 561  * gen_pool_fixed_alloc - reserve a specific region
 562  * @map: The address to base the search on
 563  * @size: The bitmap size in bits
 564  * @start: The bitnumber to start searching at
 565  * @nr: The number of zeroed bits we're looking for
 566  * @data: data for alignment
 567  * @pool: pool to get order from
 568  */
 569 unsigned long gen_pool_fixed_alloc(unsigned long *map, unsigned long size,
 570                 unsigned long start, unsigned int nr, void *data,
 571                 struct gen_pool *pool, unsigned long start_addr)
 572 {
 573         struct genpool_data_fixed *fixed_data;
 574         int order;
 575         unsigned long offset_bit;
 576         unsigned long start_bit;
 577
 578         fixed_data = data;
 579         order = pool->min_alloc_order;
 580         offset_bit = fixed_data->offset >> order;
 581         if (WARN_ON(fixed_data->offset & ((1UL << order) - 1)))
 582                 return size;
 583
 584         start_bit = bitmap_find_next_zero_area(map, size,
 585                         start + offset_bit, nr, 0);
 586         if (start_bit != offset_bit)
 587                 start_bit = size;
 588         return start_bit;
 589 }
 590 EXPORT_SYMBOL(gen_pool_fixed_alloc);
 591
 592 /**
 593  * gen_pool_first_fit_order_align - find the first available region
 594  * of memory matching the size requirement. The region will be aligned
 595  * to the order of the size specified.
 596  * @map: The address to base the search on
 597  * @size: The bitmap size in bits
 598  * @start: The bitnumber to start searching at
 599  * @nr: The number of zeroed bits we're looking for
 600  * @data: additional data - unused
 601  * @pool: pool to find the fit region memory from
 602  */
 603 unsigned long gen_pool_first_fit_order_align(unsigned long *map,
 604                 unsigned long size, unsigned long start,
 605                 unsigned int nr, void *data, struct gen_pool *pool,
 606                 unsigned long start_addr)
 607 {
 608         unsigned long align_mask = roundup_pow_of_two(nr) - 1;
 609
 610         return bitmap_find_next_zero_area(map, size, start, nr, align_mask);
 611 }
 612 EXPORT_SYMBOL(gen_pool_first_fit_order_align);
 613
 614 /**
 615  * gen_pool_best_fit - find the best fitting region of memory
 616  * macthing the size requirement (no alignment constraint)
 617  * @map: The address to base the search on
 618  * @size: The bitmap size in bits
 619  * @start: The bitnumber to start searching at
 620  * @nr: The number of zeroed bits we're looking for
 621  * @data: additional data - unused
 622  * @pool: pool to find the fit region memory from
 623  *
 624  * Iterate over the bitmap to find the smallest free region
 625  * which we can allocate the memory.
 626  */
 627 unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
 628                 unsigned long start, unsigned int nr, void *data,
 629                 struct gen_pool *pool, unsigned long start_addr)
 630 {
 631         unsigned long start_bit = size;
 632         unsigned long len = size + 1;
 633         unsigned long index;
 634
 635         index = bitmap_find_next_zero_area(map, size, start, nr, 0);
 636
 637         while (index < size) {
 638                 int next_bit = find_next_bit(map, size, index + nr);
 639                 if ((next_bit - index) < len) {
 640                         len = next_bit - index;
 641                         start_bit = index;
 642                         if (len == nr)
 643                                 return start_bit;
 644                 }
 645                 index = bitmap_find_next_zero_area(map, size,
 646                                                    next_bit + 1, nr, 0);
 647         }
 648
 649         return start_bit;
 650 }
 651 EXPORT_SYMBOL(gen_pool_best_fit);
 652
 653 static void devm_gen_pool_release(struct device *dev, void *res)
 654 {
 655         gen_pool_destroy(*(struct gen_pool **)res);
 656 }
 657
 658 static int devm_gen_pool_match(struct device *dev, void *res, void *data)
 659 {
 660         struct gen_pool **p = res;
 661
 662         /* NULL data matches only a pool without an assigned name */
 663         if (!data && !(*p)->name)
 664                 return 1;
 665
 666         if (!data || !(*p)->name)
 667                 return 0;
 668
 669         return !strcmp((*p)->name, data);
 670 }
 671
 672 /**
 673  * gen_pool_get - Obtain the gen_pool (if any) for a device
 674  * @dev: device to retrieve the gen_pool from
 675  * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
 676  *
 677  * Returns the gen_pool for the device if one is present, or NULL.
 678  */
 679 struct gen_pool *gen_pool_get(struct device *dev, const char *name)
 680 {
 681         struct gen_pool **p;
 682
 683         p = devres_find(dev, devm_gen_pool_release, devm_gen_pool_match,
 684                         (void *)name);
 685         if (!p)
 686                 return NULL;
 687         return *p;
 688 }
 689 EXPORT_SYMBOL_GPL(gen_pool_get);
 690
 691 /**
 692  * devm_gen_pool_create - managed gen_pool_create
 693  * @dev: device that provides the gen_pool
 694  * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
 695  * @nid: node selector for allocated gen_pool, %NUMA_NO_NODE for all nodes
 696  * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
 697  *
 698  * Create a new special memory pool that can be used to manage special purpose
 699  * memory not managed by the regular kmalloc/kfree interface. The pool will be
 700  * automatically destroyed by the device management code.
 701  */
 702 struct gen_pool *devm_gen_pool_create(struct device *dev, int min_alloc_order,
 703                                       int nid, const char *name)
 704 {
 705         struct gen_pool **ptr, *pool;
 706         const char *pool_name = NULL;
 707
 708         /* Check that genpool to be created is uniquely addressed on device */
 709         if (gen_pool_get(dev, name))
 710                 return ERR_PTR(-EINVAL);
 711
 712         if (name) {
 713                 pool_name = kstrdup_const(name, GFP_KERNEL);
 714                 if (!pool_name)
 715                         return ERR_PTR(-ENOMEM);
 716         }
 717
 718         ptr = devres_alloc(devm_gen_pool_release, sizeof(*ptr), GFP_KERNEL);
 719         if (!ptr)
 720                 goto free_pool_name;
 721
 722         pool = gen_pool_create(min_alloc_order, nid);
 723         if (!pool)
 724                 goto free_devres;
 725
 726         *ptr = pool;
 727         pool->name = pool_name;
 728         devres_add(dev, ptr);
 729
 730         return pool;
 731
 732 free_devres:
 733         devres_free(ptr);
 734 free_pool_name:
 735         kfree_const(pool_name);
 736
 737         return ERR_PTR(-ENOMEM);
 738 }
 739 EXPORT_SYMBOL(devm_gen_pool_create);
 740
 741 #ifdef CONFIG_OF
 742 /**
 743  * of_gen_pool_get - find a pool by phandle property
 744  * @np: device node
 745  * @propname: property name containing phandle(s)
 746  * @index: index into the phandle array
 747  *
 748  * Returns the pool that contains the chunk starting at the physical
 749  * address of the device tree node pointed at by the phandle property,
 750  * or NULL if not found.
 751  */
 752 struct gen_pool *of_gen_pool_get(struct device_node *np,
 753         const char *propname, int index)
 754 {
 755         struct platform_device *pdev;
 756         struct device_node *np_pool, *parent;
 757         const char *name = NULL;
 758         struct gen_pool *pool = NULL;
 759
 760         np_pool = of_parse_phandle(np, propname, index);
 761         if (!np_pool)
 762                 return NULL;
 763
 764         pdev = of_find_device_by_node(np_pool);
 765         if (!pdev) {
 766                 /* Check if named gen_pool is created by parent node device */
 767                 parent = of_get_parent(np_pool);
 768                 pdev = of_find_device_by_node(parent);
 769                 of_node_put(parent);
 770
 771                 of_property_read_string(np_pool, "label", &name);
 772                 if (!name)
 773                         name = np_pool->name;
 774         }
 775         if (pdev)
 776                 pool = gen_pool_get(&pdev->dev, name);
 777         of_node_put(np_pool);
 778
 779         return pool;
 780 }
 781 EXPORT_SYMBOL_GPL(of_gen_pool_get);
 782 #endif /* CONFIG_OF */