LXR linux/include/linux/flex

   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