[PATCH] Makefiles: Disable unused-variable warning (was: Re: [PATCH1/6] memcg: fix unused variable warning)

[Michal Hocko]

On Sat 24-12-11 05:00:14, Kirill A. Shutemov wrote:
> From: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx>
> 
> mm/memcontrol.c: In function âmemcg_check_eventsâ:
> mm/memcontrol.c:784:22: warning: unused variable âdo_numainfoâ [-Wunused-variable]
> 
> Signed-off-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
> ---
>  mm/memcontrol.c |    7 ++++---
>  1 files changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index d643bd6..a5e92bd 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -781,14 +781,15 @@ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
>  	/* threshold event is triggered in finer grain than soft limit */
>  	if (unlikely(mem_cgroup_event_ratelimit(memcg,
>  						MEM_CGROUP_TARGET_THRESH))) {
> -		bool do_softlimit, do_numainfo;
> +		bool do_softlimit;
>  
> -		do_softlimit = mem_cgroup_event_ratelimit(memcg,
> -						MEM_CGROUP_TARGET_SOFTLIMIT);
>  #if MAX_NUMNODES > 1
> +		bool do_numainfo;
>  		do_numainfo = mem_cgroup_event_ratelimit(memcg,
>  						MEM_CGROUP_TARGET_NUMAINFO);
>  #endif
> +		do_softlimit = mem_cgroup_event_ratelimit(memcg,
> +						MEM_CGROUP_TARGET_SOFTLIMIT);

I don't like this very much. Maybe we should get rid of both do_* and
do it with flags? But maybe it is not worth the additional code at
all...

Anyway, I am wondering why unused-but-set-variable is disabled while
unused-variable is enabled. Shouldn't we just disable it as well rather
than workaround this in the code? The warning is just pure noise in this
case.
What about something like:
---