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 */
gen_pool_add(struct gen_pool * pool,unsigned long addr,size_t size,int nid)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