| 1 | #ifndef _FLEX_ARRAY_H |
| 2 | #define _FLEX_ARRAY_H |
| 3 | |
| 4 | #include <linux/types.h> |
| 5 | #include <linux/reciprocal_div.h> |
| 6 | #include <asm/page.h> |
| 7 | |
| 8 | #define FLEX_ARRAY_PART_SIZE PAGE_SIZE |
| 9 | #define FLEX_ARRAY_BASE_SIZE PAGE_SIZE |
| 10 | |
| 11 | struct flex_array_part; |
| 12 | |
| 13 | /* |
| 14 | * This is meant to replace cases where an array-like |
| 15 | * structure has gotten too big to fit into kmalloc() |
| 16 | * and the developer is getting tempted to use |
| 17 | * vmalloc(). |
| 18 | */ |
| 19 | |
| 20 | struct flex_array { |
| 21 | union { |
| 22 | struct { |
| 23 | int element_size; |
| 24 | int total_nr_elements; |
| 25 | int elems_per_part; |
| 26 | struct reciprocal_value reciprocal_elems; |
| 27 | struct flex_array_part *parts[]; |
| 28 | }; |
| 29 | /* |
| 30 | * This little trick makes sure that |
| 31 | * sizeof(flex_array) == PAGE_SIZE |
| 32 | */ |
| 33 | char padding[FLEX_ARRAY_BASE_SIZE]; |
| 34 | }; |
| 35 | }; |
| 36 | |
| 37 | /* Number of bytes left in base struct flex_array, excluding metadata */ |
| 38 | #define FLEX_ARRAY_BASE_BYTES_LEFT \ |
| 39 | (FLEX_ARRAY_BASE_SIZE - offsetof(struct flex_array, parts)) |
| 40 | |
| 41 | /* Number of pointers in base to struct flex_array_part pages */ |
| 42 | #define FLEX_ARRAY_NR_BASE_PTRS \ |
| 43 | (FLEX_ARRAY_BASE_BYTES_LEFT / sizeof(struct flex_array_part *)) |
| 44 | |
| 45 | /* Number of elements of size that fit in struct flex_array_part */ |
| 46 | #define FLEX_ARRAY_ELEMENTS_PER_PART(size) \ |
| 47 | (FLEX_ARRAY_PART_SIZE / size) |
| 48 | |
| 49 | /* |
| 50 | * Defines a statically allocated flex array and ensures its parameters are |
| 51 | * valid. |
| 52 | */ |
| 53 | #define DEFINE_FLEX_ARRAY(__arrayname, __element_size, __total) \ |
| 54 | struct flex_array __arrayname = { { { \ |
| 55 | .element_size = (__element_size), \ |
| 56 | .total_nr_elements = (__total), \ |
| 57 | } } }; \ |
| 58 | static inline void __arrayname##_invalid_parameter(void) \ |
| 59 | { \ |
| 60 | BUILD_BUG_ON((__total) > FLEX_ARRAY_NR_BASE_PTRS * \ |
| 61 | FLEX_ARRAY_ELEMENTS_PER_PART(__element_size)); \ |
| 62 | } |
| 63 | |
| 64 | struct flex_array *flex_array_alloc(int element_size, unsigned int total, |
| 65 | gfp_t flags); |
| 66 | int flex_array_prealloc(struct flex_array *fa, unsigned int start, |
| 67 | unsigned int nr_elements, gfp_t flags); |
| 68 | void flex_array_free(struct flex_array *fa); |
| 69 | void flex_array_free_parts(struct flex_array *fa); |
| 70 | int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src, |
| 71 | gfp_t flags); |
| 72 | int flex_array_clear(struct flex_array *fa, unsigned int element_nr); |
| 73 | void *flex_array_get(struct flex_array *fa, unsigned int element_nr); |
| 74 | int flex_array_shrink(struct flex_array *fa); |
| 75 | |
| 76 | #define flex_array_put_ptr(fa, nr, src, gfp) \ |
| 77 | flex_array_put(fa, nr, (void *)&(src), gfp) |
| 78 | |
| 79 | void *flex_array_get_ptr(struct flex_array *fa, unsigned int element_nr); |
| 80 | |
| 81 | #endif /* _FLEX_ARRAY_H */ |