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1#ifndef _FLEX_ARRAY_H
2#define _FLEX_ARRAY_H
3
4#include <linux/types.h>
5#include <asm/page.h>
6
7#define FLEX_ARRAY_PART_SIZE PAGE_SIZE
8#define FLEX_ARRAY_BASE_SIZE PAGE_SIZE
9
10struct flex_array_part;
11
12/*
13 * This is meant to replace cases where an array-like
14 * structure has gotten too big to fit into kmalloc()
15 * and the developer is getting tempted to use
16 * vmalloc().
17 */
18
19struct flex_array {
20 union {
21 struct {
22 int element_size;
23 int total_nr_elements;
24 struct flex_array_part *parts[];
25 };
26 /*
27 * This little trick makes sure that
28 * sizeof(flex_array) == PAGE_SIZE
29 */
30 char padding[FLEX_ARRAY_BASE_SIZE];
31 };
32};
33
34/* Number of bytes left in base struct flex_array, excluding metadata */
35#define FLEX_ARRAY_BASE_BYTES_LEFT \
36 (FLEX_ARRAY_BASE_SIZE - offsetof(struct flex_array, parts))
37
38/* Number of pointers in base to struct flex_array_part pages */
39#define FLEX_ARRAY_NR_BASE_PTRS \
40 (FLEX_ARRAY_BASE_BYTES_LEFT / sizeof(struct flex_array_part *))
41
42/* Number of elements of size that fit in struct flex_array_part */
43#define FLEX_ARRAY_ELEMENTS_PER_PART(size) \
44 (FLEX_ARRAY_PART_SIZE / size)
45
46/*
47 * Defines a statically allocated flex array and ensures its parameters are
48 * valid.
49 */
50#define DEFINE_FLEX_ARRAY(__arrayname, __element_size, __total) \
51 struct flex_array __arrayname = { { { \
52 .element_size = (__element_size), \
53 .total_nr_elements = (__total), \
54 } } }; \
55 static inline void __arrayname##_invalid_parameter(void) \
56 { \
57 BUILD_BUG_ON((__total) > FLEX_ARRAY_NR_BASE_PTRS * \
58 FLEX_ARRAY_ELEMENTS_PER_PART(__element_size)); \
59 }
60
61struct flex_array *flex_array_alloc(int element_size, unsigned int total,
62 gfp_t flags);
63int flex_array_prealloc(struct flex_array *fa, unsigned int start,
64 unsigned int end, gfp_t flags);
65void flex_array_free(struct flex_array *fa);
66void flex_array_free_parts(struct flex_array *fa);
67int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src,
68 gfp_t flags);
69int flex_array_clear(struct flex_array *fa, unsigned int element_nr);
70void *flex_array_get(struct flex_array *fa, unsigned int element_nr);
71int flex_array_shrink(struct flex_array *fa);
72
73#define flex_array_put_ptr(fa, nr, src, gfp) \
74 flex_array_put(fa, nr, &(void *)(src), gfp)
75
76void *flex_array_get_ptr(struct flex_array *fa, unsigned int element_nr);
77
78#endif /* _FLEX_ARRAY_H */