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