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 10 struct 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 19 struct flex_array { 20 union { 21 struct { 22 int element_size; 23 int total_nr_elements; 24 int elems_per_part; 25 u32 reciprocal_elems; 26 struct flex_array_part *parts[]; 27 }; 28 /* 29 * This little trick makes sure that 30 * sizeof(flex_array) == PAGE_SIZE 31 */ 32 char padding[FLEX_ARRAY_BASE_SIZE]; 33 }; 34 }; 35 36 /* Number of bytes left in base struct flex_array, excluding metadata */ 37 #define FLEX_ARRAY_BASE_BYTES_LEFT \ 38 (FLEX_ARRAY_BASE_SIZE - offsetof(struct flex_array, parts)) 39 40 /* Number of pointers in base to struct flex_array_part pages */ 41 #define FLEX_ARRAY_NR_BASE_PTRS \ 42 (FLEX_ARRAY_BASE_BYTES_LEFT / sizeof(struct flex_array_part *)) 43 44 /* Number of elements of size that fit in struct flex_array_part */ 45 #define FLEX_ARRAY_ELEMENTS_PER_PART(size) \ 46 (FLEX_ARRAY_PART_SIZE / size) 47 48 /* 49 * Defines a statically allocated flex array and ensures its parameters are 50 * valid. 51 */ 52 #define DEFINE_FLEX_ARRAY(__arrayname, __element_size, __total) \ 53 struct flex_array __arrayname = { { { \ 54 .element_size = (__element_size), \ 55 .total_nr_elements = (__total), \ 56 } } }; \ 57 static inline void __arrayname##_invalid_parameter(void) \ 58 { \ 59 BUILD_BUG_ON((__total) > FLEX_ARRAY_NR_BASE_PTRS * \ 60 FLEX_ARRAY_ELEMENTS_PER_PART(__element_size)); \ 61 } 62 63 struct flex_array *flex_array_alloc(int element_size, unsigned int total, 64 gfp_t flags); 65 int flex_array_prealloc(struct flex_array *fa, unsigned int start, 66 unsigned int nr_elements, gfp_t flags); 67 void flex_array_free(struct flex_array *fa); 68 void flex_array_free_parts(struct flex_array *fa); 69 int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src, 70 gfp_t flags); 71 int flex_array_clear(struct flex_array *fa, unsigned int element_nr); 72 void *flex_array_get(struct flex_array *fa, unsigned int element_nr); 73 int flex_array_shrink(struct flex_array *fa); 74 75 #define flex_array_put_ptr(fa, nr, src, gfp) \ 76 flex_array_put(fa, nr, (void *)&(src), gfp) 77 78 void *flex_array_get_ptr(struct flex_array *fa, unsigned int element_nr); 79 80 #endif /* _FLEX_ARRAY_H */ 81