Introduce two helper macros to calculate the size of the structure with trailing aligned data and to retrieve the pointer to that data. Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> --- include/linux/overflow.h | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-) diff --git a/include/linux/overflow.h b/include/linux/overflow.h index bc390f026128..b93bbf1b6aaa 100644 --- a/include/linux/overflow.h +++ b/include/linux/overflow.h @@ -2,9 +2,10 @@ #ifndef __LINUX_OVERFLOW_H #define __LINUX_OVERFLOW_H +#include <linux/align.h> #include <linux/compiler.h> -#include <linux/limits.h> #include <linux/const.h> +#include <linux/limits.h> /* * We need to compute the minimum and maximum values representable in a given @@ -337,6 +338,30 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend) */ #define array3_size(a, b, c) size_mul(size_mul(a, b), c) +/** + * struct_size_with_data() - Calculate size of structure with trailing aligned data. + * @p: Pointer to the structure. + * @a: Alignment in bytes before trailing data. + * @s: Data size in bytes (must not be 0). + * + * Calculates size of memory needed for structure of @p followed by an + * aligned data of size @s. + * + * Return: number of bytes needed or SIZE_MAX on overflow. + */ +#define struct_size_with_data(p, a, s) size_add(ALIGN(sizeof(*(p)), (a)), (s)) + +/** + * struct_data_pointer - Calculate offset of the trailing data reserved with + * struct_size_with_data(). + * @p: Pointer to the structure. + * @a: Alignment in bytes before trailing data. + * + * Return: offset in bytes to the trailing data reserved with + * struct_size_with_data(). + */ +#define struct_data_pointer(p, a) PTR_ALIGN((void *)((p) + 1), (a)) + /** * flex_array_size() - Calculate size of a flexible array member * within an enclosing structure. -- 2.43.0.rc1.1.gbec44491f096
