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TOMOYO Linux Cross Reference
Linux/include/linux/genalloc.h

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  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  */
 40 typedef 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  */
 49 struct 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  */
 61 struct 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 
 70 extern struct gen_pool *gen_pool_create(int, int);
 71 extern phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long);
 72 extern 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  */
 86 static 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 }
 91 extern void gen_pool_destroy(struct gen_pool *);
 92 extern unsigned long gen_pool_alloc(struct gen_pool *, size_t);
 93 extern void gen_pool_free(struct gen_pool *, unsigned long, size_t);
 94 extern void gen_pool_for_each_chunk(struct gen_pool *,
 95         void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);
 96 extern size_t gen_pool_avail(struct gen_pool *);
 97 extern size_t gen_pool_size(struct gen_pool *);
 98 
 99 extern void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo,
100                 void *data);
101 
102 extern unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
103                 unsigned long start, unsigned int nr, void *data);
104 
105 extern 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 

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