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include/linux/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 */ |