Re: [PATCH] kernel.h: add IS_PTR_ALIGNED() macro

From: Andrew Morton
Date: Wed Mar 29 2017 - 17:37:08 EST


On Wed, 29 Mar 2017 19:22:10 +0900 Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> wrote:

> We often check if a pointer has a specific alignment. Because the
> '&' (bitwise AND) operator cannot take a pointer for the operand,
> so we need a cast like, IS_ALIGNED((unsigned long)p, a).
>
> IS_PTR_ALIGNED will be useful as a shorthand.
>
> ...
>
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -50,6 +50,7 @@
> #define __ALIGN_MASK(x, mask) __ALIGN_KERNEL_MASK((x), (mask))
> #define PTR_ALIGN(p, a) ((typeof(p))ALIGN((unsigned long)(p), (a)))
> #define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) == 0)
> +#define IS_PTR_ALIGNED(p, a) (IS_ALIGNED((unsigned long)p, a))
>
> /* generic data direction definitions */
> #define READ 0

It would be nice to see some conversions which actually use this new
macro.