Re: [PATCH v3 2/5] Documentation/locking/atomic: Fix atomic-set litmus test

[Alan Stern <stern@rowland.harvard.edu>]

On Thu, 27 Feb 2020, Boqun Feng wrote:

> Currently the litmus test "atomic-set" in atomic_t.txt has a few things
> to be improved:
> 
> 1)	The CPU/Processor numbers "P1,P2" are not only inconsistent with
> 	the rest of the document, which uses "CPU0" and "CPU1", but also
> 	unacceptable by the herd tool, which requires processors start
> 	at "P0".
> 
> 2)	The initialization block uses a "atomic_set()", which is OK, but
> 	it's better to use ATOMIC_INIT() to make clear this is an
> 	initialization.
> 
> 3)	The return value of atomic_add_unless() is discarded
> 	inexplicitly, which is OK for C language, but it will be helpful
> 	to the herd tool if we use a void cast to make the discard
> 	explicit.
> 
> Therefore fix these and this is the preparation for adding the litmus
> test into memory-model litmus-tests directory so that people can
> understand better about our requirements of atomic APIs and klitmus tool
> can be used to generate tests.
> 
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>

Patch 5/5 in this series does basically the same thing for 
Atomic-RMW+mb__after_atomic-is-stronger-than-acquire.  How come you 
used one patch for that, but this is split into two patches (2/5 and 
4/5)?

Alan

> ---
>  Documentation/atomic_t.txt | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/atomic_t.txt b/Documentation/atomic_t.txt
> index 0ab747e0d5ac..ceb85ada378e 100644
> --- a/Documentation/atomic_t.txt
> +++ b/Documentation/atomic_t.txt
> @@ -91,15 +91,15 @@ ops. That is:
>    C atomic-set
>  
>    {
> -    atomic_set(v, 1);
> +    atomic_t v = ATOMIC_INIT(1);
>    }
>  
> -  P1(atomic_t *v)
> +  P0(atomic_t *v)
>    {
> -    atomic_add_unless(v, 1, 0);
> +    (void)atomic_add_unless(v, 1, 0);
>    }
>  
> -  P2(atomic_t *v)
> +  P1(atomic_t *v)
>    {
>      atomic_set(v, 0);
>    }
>