Hi,
On 2023/09/24 1:32, SeongJae Park wrote:
> From: SeongJae Park <sj38.park@xxxxxxxxx>
>
> 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 <sj38.park@xxxxxxxxx>
> ---
> 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
