From: Jani Nikula Date: Wed, 14 Aug 2024 10:00:34 +0000 (+0300) Subject: string: add mem_is_zero() helper to check if memory area is all zeros X-Git-Tag: v6.12-rc1~126^2~20^2~36 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3942bb49728ad9e1f94d953a88af169a8f5d8099;p=thirdparty%2Flinux.git string: add mem_is_zero() helper to check if memory area is all zeros Almost two thirds of the memchr_inv() usages check if the memory area is all zeros, with no interest in where in the buffer the first non-zero byte is located. Checking for !memchr_inv(s, 0, n) is also not very intuitive or discoverable. Add an explicit mem_is_zero() helper for this use case. Reviewed-by: Kees Cook Reviewed-by: Andy Shevchenko Link: https://patchwork.freedesktop.org/patch/msgid/20240814100035.3100852-1-jani.nikula@intel.com Signed-off-by: Jani Nikula --- diff --git a/include/linux/string.h b/include/linux/string.h index 9edace076ddbf..5855c5626b4b7 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -279,6 +279,18 @@ static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt) void *memchr_inv(const void *s, int c, size_t n); char *strreplace(char *str, char old, char new); +/** + * mem_is_zero - Check if an area of memory is all 0's. + * @s: The memory area + * @n: The size of the area + * + * Return: True if the area of memory is all 0's. + */ +static inline bool mem_is_zero(const void *s, size_t n) +{ + return !memchr_inv(s, 0, n); +} + extern void kfree_const(const void *x); extern char *kstrdup(const char *s, gfp_t gfp) __malloc;