Re: [PATCH 10/10] memorder: Fix wrong primitive names in a quick quizz

Hi,

On 2023/09/24 1:32, SeongJae Park wrote:
> From: SeongJae Park <[email protected]>
> 
> memorder.tex explains READ_ONCE() is having smp_mb(), but the following
> quick quizz asks why it has mb() instead of rmb().  Fix the wrong names
> in the quick quizz.
> 
> Signed-off-by: SeongJae Park <[email protected]>
> ---
>  memorder/memorder.tex | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/memorder/memorder.tex b/memorder/memorder.tex
> index 5c978fbe..b3acc14a 100644
> --- a/memorder/memorder.tex
> +++ b/memorder/memorder.tex
> @@ -5491,7 +5491,7 @@ Alpha is the only CPU whose \co{READ_ONCE()} includes an \co{smp_mb()}.
>  \QuickQuizSeries{%
>  \QuickQuizB{
>  	Why does Alpha's \co{READ_ONCE()} include an
> -	\co{mb()} rather than \co{rmb()}?
> +	\co{smp_mb()} rather than \co{smp_rmb()}?

Definition in Linux kernel's arch/alpha/include/asm/rwonce.h reads:

#define __READ_ONCE(x)							\
({									\
	__unqual_scalar_typeof(x) __x =					\
		(*(volatile typeof(__x) *)(&(x)));			\
	mb();								\
	(typeof(x))__x;							\
})

So I don't think this change is needed.

As this quiz is talking about Alpha ISA, how about rewording the
quiz to:

    Why does Alpha's \co{READ_ONCE()} include an
    \co{mb} instruction rather than a \co{rmb}?

        Thanks, Akira

>  }\QuickQuizAnswerB{
>  	Alpha has only \co{mb} and \co{wmb} instructions,
>  	so \co{smp_rmb()} would be implemented by the Alpha \co{mb}
> -- 
> 2.17.1