linux-kernel - Re: [PATCH] rculist: Silence unused-value warning.

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Date:   Sun, 19 Jul 2020 09:07:47 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Suraj Upadhyay <usuraj35@...il.com>
Cc:     josh@...htriplett.org, rostedt@...dmis.org,
        mathieu.desnoyers@...icios.com, jiangshanlai@...il.com,
        joel@...lfernandes.org, madhuparnabhowmik10@...il.com,
        rcu@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rculist: Silence unused-value warning.

On Sun, Jul 19, 2020 at 04:20:37PM +0530, Suraj Upadhyay wrote:
> The macro __list_check_srcu is used as a statement inside a for loop.
> 
> __list_check_srcu becomes "true" when CONFIG_PROVE_RCU_LIST is not defined.
> This results in compiler warning about an unused value ("true").
> 
> Silence the compiler warning about the unused value "true"
> by replacing it with an empty expression.
> 
> Signed-off-by: Suraj Upadhyay <usuraj35@...il.com>

Like this, you mean, give or take whitespace?  ;-)

https://lore.kernel.org/lkml/20200718001259.GY9247@paulmck-ThinkPad-P72/

May I add your Tested-by?

							Thanx, Paul

> ---
>  include/linux/rculist.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/rculist.h b/include/linux/rculist.h
> index de9385b9158e..8b8e0584c473 100644
> --- a/include/linux/rculist.h
> +++ b/include/linux/rculist.h
> @@ -73,7 +73,7 @@ static inline void INIT_LIST_HEAD_RCU(struct list_head *list)
>  #define __list_check_rcu(dummy, cond, extra...)				\
>  	({ check_arg_count_one(extra); })
>  
> -#define __list_check_srcu(cond) true
> +#define __list_check_srcu(cond) ({})
>  #endif
>  
>  /*
> -- 
> 2.17.1
>