diff options
Diffstat (limited to 'include/linux/flex_array.h')
-rw-r--r-- | include/linux/flex_array.h | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/include/linux/flex_array.h b/include/linux/flex_array.h new file mode 100644 index 00000000000..1d747f72298 --- /dev/null +++ b/include/linux/flex_array.h @@ -0,0 +1,73 @@ +#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); + +#endif /* _FLEX_ARRAY_H */ |