On Wed, Sep 12, 2018 at 07:53:24PM +0900, Akira Yokosawa wrote:
> >From 13fa1b9b162483df5d88b7aefe408a4e17e83338 Mon Sep 17 00:00:00 2001
> From: Akira Yokosawa <akiyks@xxxxxxxxx>
> Date: Wed, 12 Sep 2018 19:27:41 +0900
> Subject: [PATCH] CodeSamples/count: Use READ_ONCE/WRITE_ONCE in count_nonatomic.c
>
> Without them, inlined accesses can be optimized away by "-O3".
That code was written in a far more innocent time when compilers were
far less aggressive, wasn't it?
Great catch, both on the data and on the code, thank you! Applied and
pushed.
Thanx, Paul
> Signed-off-by: Akira Yokosawa <akiyks@xxxxxxxxx>
> ---
> CodeSamples/count/count_nonatomic.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/CodeSamples/count/count_nonatomic.c b/CodeSamples/count/count_nonatomic.c
> index 90979c5..50df475 100644
> --- a/CodeSamples/count/count_nonatomic.c
> +++ b/CodeSamples/count/count_nonatomic.c
> @@ -25,12 +25,12 @@ unsigned long counter = 0;
>
> __inline__ void inc_count(void)
> {
> - counter++;
> + WRITE_ONCE(counter, READ_ONCE(counter) + 1);
> }
>
> __inline__ unsigned long read_count(void)
> {
> - return counter;
> + return READ_ONCE(counter);
> }
>
> __inline__ void count_init(void)
> --
> 2.7.4
>
>
