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SubjectRe: [PATCH] Documentation/memory-barriers: fix wrong comment in example
On Sat, Feb 20, 2016 at 03:01:08PM +0900, SeongJae Park wrote:
> There is wrong comment in example for compiler store omit behavior. It
> shows example of the problem and than problem solved version code.
> However, the comment in the solved version is still same with not solved
> version. Fix the wrong statement with this commit.
>
> Signed-off-by: SeongJae Park <sj38.park@gmail.com>

Hmmm... The code between the two stores of zero to "a" is intended to
remain the same in the broken and fixed versions. So the only change
is from "a = 0" to "WRITE_ONCE(a, 0)". Note that it is some other
CPU that did the third store to "a".

Or am I missing your point here?

Thanx, Paul

> ---
> Documentation/memory-barriers.txt | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
> index 061ff29..b4754c7 100644
> --- a/Documentation/memory-barriers.txt
> +++ b/Documentation/memory-barriers.txt
> @@ -1471,7 +1471,7 @@ of optimizations:
> wrong guess:
>
> WRITE_ONCE(a, 0);
> - /* Code that does not store to variable a. */
> + /* Code that does store to variable a. */
> WRITE_ONCE(a, 0);
>
> (*) The compiler is within its rights to reorder memory accesses unless
> --
> 1.9.1
>

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