projects/linux·blob v3.7-rc3 · refs

108 lines · 4.0 KiB

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__ */