flex_array.h
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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _FLEX_ARRAY_H
#define _FLEX_ARRAY_H
#include <linux/types.h>
#include <linux/reciprocal_div.h>
#include <asm/page.h>
#define FLEX_ARRAY_PART_SIZE PAGE_SIZE
#define FLEX_ARRAY_BASE_SIZE PAGE_SIZE
struct flex_array_part;
/*
* This is meant to replace cases where an array-like
* structure has gotten too big to fit into kmalloc()
* and the developer is getting tempted to use
* vmalloc().
*/
struct flex_array {
union {
struct {
int element_size;
int total_nr_elements;
int elems_per_part;
struct reciprocal_value reciprocal_elems;
struct flex_array_part *parts[];
};
/*
* This little trick makes sure that
* sizeof(flex_array) == PAGE_SIZE
*/
char padding[FLEX_ARRAY_BASE_SIZE];
};
};
/* Number of bytes left in base struct flex_array, excluding metadata */
#define FLEX_ARRAY_BASE_BYTES_LEFT \
(FLEX_ARRAY_BASE_SIZE - offsetof(struct flex_array, parts))
/* Number of pointers in base to struct flex_array_part pages */
#define FLEX_ARRAY_NR_BASE_PTRS \
(FLEX_ARRAY_BASE_BYTES_LEFT / sizeof(struct flex_array_part *))
/* Number of elements of size that fit in struct flex_array_part */
#define FLEX_ARRAY_ELEMENTS_PER_PART(size) \
(FLEX_ARRAY_PART_SIZE / size)
/*
* Defines a statically allocated flex array and ensures its parameters are
* valid.
*/
#define DEFINE_FLEX_ARRAY(__arrayname, __element_size, __total) \
struct flex_array __arrayname = { { { \
.element_size = (__element_size), \
.total_nr_elements = (__total), \
} } }; \
static inline void __arrayname##_invalid_parameter(void) \
{ \
BUILD_BUG_ON((__total) > FLEX_ARRAY_NR_BASE_PTRS * \
FLEX_ARRAY_ELEMENTS_PER_PART(__element_size)); \
}
/**
* flex_array_alloc() - Creates a flexible array.
* @element_size: individual object size.
* @total: maximum number of objects which can be stored.
* @flags: GFP flags
*
* Return: Returns an object of structure flex_array.
*/
struct flex_array *flex_array_alloc(int element_size, unsigned int total,
gfp_t flags);
/**
* flex_array_prealloc() - Ensures that memory for the elements indexed in the
* range defined by start and nr_elements has been allocated.
* @fa: array to allocate memory to.
* @start: start address
* @nr_elements: number of elements to be allocated.
* @flags: GFP flags
*
*/
int flex_array_prealloc(struct flex_array *fa, unsigned int start,
unsigned int nr_elements, gfp_t flags);
/**
* flex_array_free() - Removes all elements of a flexible array.
* @fa: array to be freed.
*/
void flex_array_free(struct flex_array *fa);
/**
* flex_array_free_parts() - Removes all elements of a flexible array, but
* leaves the array itself in place.
* @fa: array to be emptied.
*/
void flex_array_free_parts(struct flex_array *fa);
/**
* flex_array_put() - Stores data into a flexible array.
* @fa: array where element is to be stored.
* @element_nr: position to copy, must be less than the maximum specified when
* the array was created.
* @src: data source to be copied into the array.
* @flags: GFP flags
*
* Return: Returns zero on success, a negative error code otherwise.
*/
int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src,
gfp_t flags);
/**
* flex_array_clear() - Clears an individual element in the array, sets the
* given element to FLEX_ARRAY_FREE.
* @element_nr: element position to clear.
* @fa: array to which element to be cleared belongs.
*
* Return: Returns zero on success, -EINVAL otherwise.
*/
int flex_array_clear(struct flex_array *fa, unsigned int element_nr);
/**
* flex_array_get() - Retrieves data into a flexible array.
*
* @element_nr: Element position to retrieve data from.
* @fa: array from which data is to be retrieved.
*
* Return: Returns a pointer to the data element, or NULL if that
* particular element has never been allocated.
*/
void *flex_array_get(struct flex_array *fa, unsigned int element_nr);
/**
* flex_array_shrink() - Reduces the allocated size of an array.
* @fa: array to shrink.
*
* Return: Returns number of pages of memory actually freed.
*
*/
int flex_array_shrink(struct flex_array *fa);
#define flex_array_put_ptr(fa, nr, src, gfp) \
flex_array_put(fa, nr, (void *)&(src), gfp)
void *flex_array_get_ptr(struct flex_array *fa, unsigned int element_nr);
#endif /* _FLEX_ARRAY_H */