[net-next-2.6.git] / include / linux / flex_array.h

#ifndef _FLEX_ARRAY_H
#define _FLEX_ARRAY_H

#include <linux/types.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;
			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));	\
	}

struct flex_array *flex_array_alloc(int element_size, unsigned int total,
		gfp_t flags);
int flex_array_prealloc(struct flex_array *fa, unsigned int start,
		unsigned int end, gfp_t flags);
void flex_array_free(struct flex_array *fa);
void flex_array_free_parts(struct flex_array *fa);
int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src,
		gfp_t flags);
int flex_array_clear(struct flex_array *fa, unsigned int element_nr);
void *flex_array_get(struct flex_array *fa, unsigned int element_nr);
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 */
Commit	Line	Data
534acc05 DH	1	#ifndef _FLEX_ARRAY_H
	2	#define _FLEX_ARRAY_H
	3
	4	#include <linux/types.h>
	5	#include <asm/page.h>
	6
	7	#define FLEX_ARRAY_PART_SIZE PAGE_SIZE
	8	#define FLEX_ARRAY_BASE_SIZE PAGE_SIZE
	9
	10	struct flex_array_part;
	11
	12	/*
	13	* This is meant to replace cases where an array-like
	14	* structure has gotten too big to fit into kmalloc()
	15	* and the developer is getting tempted to use
	16	* vmalloc().
	17	*/
	18
	19	struct flex_array {
	20	union {
	21	struct {
	22	int element_size;
	23	int total_nr_elements;
8e7ee270	24	struct flex_array_part *parts[];
534acc05 DH	25	};
	26	/*
	27	* This little trick makes sure that
	28	* sizeof(flex_array) == PAGE_SIZE
	29	*/
	30	char padding[FLEX_ARRAY_BASE_SIZE];
	31	};
	32	};
	33
45b588d6 DR	34	/* Number of bytes left in base struct flex_array, excluding metadata */
	35	#define FLEX_ARRAY_BASE_BYTES_LEFT \
	36	(FLEX_ARRAY_BASE_SIZE - offsetof(struct flex_array, parts))
	37
	38	/* Number of pointers in base to struct flex_array_part pages */
	39	#define FLEX_ARRAY_NR_BASE_PTRS \
	40	(FLEX_ARRAY_BASE_BYTES_LEFT / sizeof(struct flex_array_part *))
	41
	42	/* Number of elements of size that fit in struct flex_array_part */
	43	#define FLEX_ARRAY_ELEMENTS_PER_PART(size) \
	44	(FLEX_ARRAY_PART_SIZE / size)
	45
	46	/*
	47	* Defines a statically allocated flex array and ensures its parameters are
	48	* valid.
	49	*/
	50	#define DEFINE_FLEX_ARRAY(__arrayname, __element_size, __total) \
	51	struct flex_array __arrayname = { { { \
	52	.element_size = (__element_size), \
	53	.total_nr_elements = (__total), \
	54	} } }; \
	55	static inline void __arrayname##_invalid_parameter(void) \
	56	{ \
	57	BUILD_BUG_ON((__total) > FLEX_ARRAY_NR_BASE_PTRS * \
	58	FLEX_ARRAY_ELEMENTS_PER_PART(__element_size)); \
	59	}
534acc05	60
b62e408c DR	61	struct flex_array *flex_array_alloc(int element_size, unsigned int total,
	62	gfp_t flags);
	63	int flex_array_prealloc(struct flex_array *fa, unsigned int start,
	64	unsigned int end, gfp_t flags);
534acc05 DH	65	void flex_array_free(struct flex_array *fa);
534acc05 DH	66	void flex_array_free_parts(struct flex_array *fa);
b62e408c	67	int flex_array_put(struct flex_array fa, unsigned int element_nr, void src,
534acc05	68	gfp_t flags);
e6de3988	69	int flex_array_clear(struct flex_array *fa, unsigned int element_nr);
b62e408c	70	void flex_array_get(struct flex_array fa, unsigned int element_nr);
4af5a2f7	71	int flex_array_shrink(struct flex_array *fa);
534acc05	72
ea98eed9 EP	73	#define flex_array_put_ptr(fa, nr, src, gfp) \
	74	flex_array_put(fa, nr, &(void *)(src), gfp)
	75
	76	void flex_array_get_ptr(struct flex_array fa, unsigned int element_nr);
	77
534acc05	78	#endif /* _FLEX_ARRAY_H */