LXR linux/include/linux/genalloc.h

   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 * This source code is licensed under the GNU General Public License,
  26 * Version 2.  See the file COPYING for more details.
  27 */
  28
  29
  30#ifndef __GENALLOC_H__
  31#define __GENALLOC_H__
  32/**
  33 * Allocation callback function type definition
  34 * @map: Pointer to bitmap
  35 * @size: The bitmap size in bits
  36 * @start: The bitnumber to start searching at
  37 * @nr: The number of zeroed bits we're looking for
  38 * @data: optional additional data used by @genpool_algo_t
  39 */
  40typedef unsigned long (*genpool_algo_t)(unsigned long *map,
  41                        unsigned long size,
  42                        unsigned long start,
  43                        unsigned int nr,
  44                        void *data);
  45
  46/*
  47 *  General purpose special memory pool descriptor.
  48 */
  49struct gen_pool {
  50        spinlock_t lock;
  51        struct list_head chunks;        /* list of chunks in this pool */
  52        int min_alloc_order;            /* minimum allocation order */
  53
  54        genpool_algo_t algo;            /* allocation function */
  55        void *data;
  56};
  57
  58/*
  59 *  General purpose special memory pool chunk descriptor.
  60 */
  61struct gen_pool_chunk {
  62        struct list_head next_chunk;    /* next chunk in pool */
  63        atomic_t avail;
  64        phys_addr_t phys_addr;          /* physical starting address of memory chunk */
  65        unsigned long start_addr;       /* starting address of memory chunk */
  66        unsigned long end_addr;         /* ending address of memory chunk */
  67        unsigned long bits[0];          /* bitmap for allocating memory chunk */
  68};
  69
  70extern struct gen_pool *gen_pool_create(int, int);
  71extern phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long);
  72extern int gen_pool_add_virt(struct gen_pool *, unsigned long, phys_addr_t,
  73                             size_t, int);
  74/**
  75 * gen_pool_add - add a new chunk of special memory to the pool
  76 * @pool: pool to add new memory chunk to
  77 * @addr: starting address of memory chunk to add to pool
  78 * @size: size in bytes of the memory chunk to add to pool
  79 * @nid: node id of the node the chunk structure and bitmap should be
  80 *       allocated on, or -1
  81 *
  82 * Add a new chunk of special memory to the specified pool.
  83 *
  84 * Returns 0 on success or a -ve errno on failure.
  85 */
  86static inline int gen_pool_add(struct gen_pool *pool, unsigned long addr,
  87                               size_t size, int nid)
  88{
  89        return gen_pool_add_virt(pool, addr, -1, size, nid);
  90}
  91extern void gen_pool_destroy(struct gen_pool *);
  92extern unsigned long gen_pool_alloc(struct gen_pool *, size_t);
  93extern void gen_pool_free(struct gen_pool *, unsigned long, size_t);
  94extern void gen_pool_for_each_chunk(struct gen_pool *,
  95        void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);
  96extern size_t gen_pool_avail(struct gen_pool *);
  97extern size_t gen_pool_size(struct gen_pool *);
  98
  99extern void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo,
 100                void *data);
 101
 102extern unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
 103                unsigned long start, unsigned int nr, void *data);
 104
 105extern unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
 106                unsigned long start, unsigned int nr, void *data);
 107
 108#endif /* __GENALLOC_H__ */
 109