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 11struct 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 20struct 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 64struct flex_array *flex_array_alloc(int element_size, unsigned int total, 65 gfp_t flags); 66int flex_array_prealloc(struct flex_array *fa, unsigned int start, 67 unsigned int nr_elements, gfp_t flags); 68void flex_array_free(struct flex_array *fa); 69void flex_array_free_parts(struct flex_array *fa); 70int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src, 71 gfp_t flags); 72int flex_array_clear(struct flex_array *fa, unsigned int element_nr); 73void *flex_array_get(struct flex_array *fa, unsigned int element_nr); 74int 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 79void *flex_array_get_ptr(struct flex_array *fa, unsigned int element_nr); 80 81#endif /* _FLEX_ARRAY_H */ 82