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Diffstat (limited to 'include/linux/genalloc.h')
| -rw-r--r-- | include/linux/genalloc.h | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/include/linux/genalloc.h b/include/linux/genalloc.h new file mode 100644 index 00000000..5e98eeb2 --- /dev/null +++ b/include/linux/genalloc.h @@ -0,0 +1,81 @@ +/* + * Basic general purpose allocator for managing special purpose + * memory, for example, memory that is not managed by the regular + * kmalloc/kfree interface. Uses for this includes on-device special + * memory, uncached memory etc. + * + * It is safe to use the allocator in NMI handlers and other special + * unblockable contexts that could otherwise deadlock on locks. This + * is implemented by using atomic operations and retries on any + * conflicts. The disadvantage is that there may be livelocks in + * extreme cases. For better scalability, one allocator can be used + * for each CPU. + * + * The lockless operation only works if there is enough memory + * available. If new memory is added to the pool a lock has to be + * still taken. So any user relying on locklessness has to ensure + * that sufficient memory is preallocated. + * + * The basic atomic operation of this allocator is cmpxchg on long. + * On architectures that don't have NMI-safe cmpxchg implementation, + * the allocator can NOT be used in NMI handler. So code uses the + * allocator in NMI handler should depend on + * CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG. + * + * This source code is licensed under the GNU General Public License, + * Version 2. See the file COPYING for more details. + */ + + +#ifndef __GENALLOC_H__ +#define __GENALLOC_H__ +/* + * General purpose special memory pool descriptor. + */ +struct gen_pool { + spinlock_t lock; + struct list_head chunks; /* list of chunks in this pool */ + int min_alloc_order; /* minimum allocation order */ +}; + +/* + * General purpose special memory pool chunk descriptor. + */ +struct gen_pool_chunk { + struct list_head next_chunk; /* next chunk in pool */ + atomic_t avail; + phys_addr_t phys_addr; /* physical starting address of memory chunk */ + unsigned long start_addr; /* starting address of memory chunk */ + unsigned long end_addr; /* ending address of memory chunk */ + unsigned long bits[0]; /* bitmap for allocating memory chunk */ +}; + +extern struct gen_pool *gen_pool_create(int, int); +extern phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long); +extern int gen_pool_add_virt(struct gen_pool *, unsigned long, phys_addr_t, + size_t, int); +/** + * gen_pool_add - add a new chunk of special memory to the pool + * @pool: pool to add new memory chunk to + * @addr: starting address of memory chunk to add to pool + * @size: size in bytes of the memory chunk to add to pool + * @nid: node id of the node the chunk structure and bitmap should be + * allocated on, or -1 + * + * Add a new chunk of special memory to the specified pool. + * + * Returns 0 on success or a -ve errno on failure. + */ +static inline int gen_pool_add(struct gen_pool *pool, unsigned long addr, + size_t size, int nid) +{ + return gen_pool_add_virt(pool, addr, -1, size, nid); +} +extern void gen_pool_destroy(struct gen_pool *); +extern unsigned long gen_pool_alloc(struct gen_pool *, size_t); +extern void gen_pool_free(struct gen_pool *, unsigned long, size_t); +extern void gen_pool_for_each_chunk(struct gen_pool *, + void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *); +extern size_t gen_pool_avail(struct gen_pool *); +extern size_t gen_pool_size(struct gen_pool *); +#endif /* __GENALLOC_H__ */ |