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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  *  General purpose special memory pool descriptor.
 34  */
 35 struct gen_pool {
 36         spinlock_t lock;
 37         struct list_head chunks;        /* list of chunks in this pool */
 38         int min_alloc_order;            /* minimum allocation order */
 39 };
 40 
 41 /*
 42  *  General purpose special memory pool chunk descriptor.
 43  */
 44 struct gen_pool_chunk {
 45         struct list_head next_chunk;    /* next chunk in pool */
 46         atomic_t avail;
 47         phys_addr_t phys_addr;          /* physical starting address of memory chunk */
 48         unsigned long start_addr;       /* starting address of memory chunk */
 49         unsigned long end_addr;         /* ending address of memory chunk */
 50         unsigned long bits[0];          /* bitmap for allocating memory chunk */
 51 };
 52 
 53 extern struct gen_pool *gen_pool_create(int, int);
 54 extern phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long);
 55 extern int gen_pool_add_virt(struct gen_pool *, unsigned long, phys_addr_t,
 56                              size_t, int);
 57 /**
 58  * gen_pool_add - add a new chunk of special memory to the pool
 59  * @pool: pool to add new memory chunk to
 60  * @addr: starting address of memory chunk to add to pool
 61  * @size: size in bytes of the memory chunk to add to pool
 62  * @nid: node id of the node the chunk structure and bitmap should be
 63  *       allocated on, or -1
 64  *
 65  * Add a new chunk of special memory to the specified pool.
 66  *
 67  * Returns 0 on success or a -ve errno on failure.
 68  */
 69 static inline int gen_pool_add(struct gen_pool *pool, unsigned long addr,
 70                                size_t size, int nid)
 71 {
 72         return gen_pool_add_virt(pool, addr, -1, size, nid);
 73 }
 74 extern void gen_pool_destroy(struct gen_pool *);
 75 extern unsigned long gen_pool_alloc(struct gen_pool *, size_t);
 76 extern void gen_pool_free(struct gen_pool *, unsigned long, size_t);
 77 extern void gen_pool_for_each_chunk(struct gen_pool *,
 78         void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);
 79 extern size_t gen_pool_avail(struct gen_pool *);
 80 extern size_t gen_pool_size(struct gen_pool *);
 81 #endif /* __GENALLOC_H__ */
 82 

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