Re: [PATCH v6 1/5] vdso/math64: Use OPTIMIZER_HIDE_VAR() in __iter_div_u64_rem()

[Thomas Weißschuh]

On Wed, Sep 30, 2026 at 11:44:56PM +0800, Zhan Xusheng wrote:
(...)

> Signed-off-by: Zhan Xusheng <zhanxusheng@xxxxxxxxxx>
> ---
>  include/vdso/math64.h | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/include/vdso/math64.h b/include/vdso/math64.h
> index 22ae212f8b28..c628d6cf447c 100644
> --- a/include/vdso/math64.h
> +++ b/include/vdso/math64.h
> @@ -2,15 +2,16 @@
>  #ifndef __VDSO_MATH64_H
>  #define __VDSO_MATH64_H
>  
> -static __always_inline u32
> -__iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
> +static __always_inline u32 __iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
>  {
>  	u32 ret = 0;
>  
>  	while (dividend >= divisor) {
> -		/* The following asm() prevents the compiler from
> -		   optimising this loop into a modulo operation.  */
> -		asm("" : "+rm"(dividend));
> +		/*
> +		 * Prevent the compiler from optimising this loop into a
> +		 * modulo operation.
> +		 */
> +		OPTIMIZER_HIDE_VAR(dividend);

This still requires '#include <linux/compiler.h>'.
See https://lore.kernel.org/lkml/202609300626.zwNjKaO6-lkp@xxxxxxxxx/


>  
>  		dividend -= divisor;
>  		ret++;
> -- 
> 2.43.0
>