linux-kernel - Re: [PATCH 1/2] refscale: simplify the errexit checkpoint

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Date:   Fri, 22 Oct 2021 16:10:48 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Li Zhijian <lizhijian@...fujitsu.com>
Cc:     dave@...olabs.net, josh@...htriplett.org, rostedt@...dmis.org,
        mathieu.desnoyers@...icios.com, jiangshanlai@...il.com,
        joel@...lfernandes.org, rcu@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] refscale: simplify the errexit checkpoint

On Fri, Oct 22, 2021 at 06:51:10PM +0800, Li Zhijian wrote:
> Signed-off-by: Li Zhijian <lizhijian@...fujitsu.com>

Good catch!

But given that errexit is only set once at the beginning, why not
eliminate this local variable in favor of a goto at the point that it
is currently assigned to?  That would permit further simplification.

							Thanx, Paul

> ---
>  kernel/rcu/refscale.c | 17 ++++++++---------
>  1 file changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
> index 66dc14cf5687..2cbe2a2ba387 100644
> --- a/kernel/rcu/refscale.c
> +++ b/kernel/rcu/refscale.c
> @@ -698,26 +698,25 @@ static int main_func(void *arg)
>  	// Print the average of all experiments
>  	SCALEOUT("END OF TEST. Calculating average duration per loop (nanoseconds)...\n");
>  
> -	if (!errexit) {
> -		buf[0] = 0;
> -		strcat(buf, "\n");
> -		strcat(buf, "Runs\tTime(ns)\n");
> -	}
> +	if (errexit)
> +		goto err;
> +
> +	buf[0] = 0;
> +	strcat(buf, "\n");
> +	strcat(buf, "Runs\tTime(ns)\n");
>  
>  	for (exp = 0; exp < nruns; exp++) {
>  		u64 avg;
>  		u32 rem;
>  
> -		if (errexit)
> -			break;
>  		avg = div_u64_rem(result_avg[exp], 1000, &rem);
>  		sprintf(buf1, "%d\t%llu.%03u\n", exp + 1, avg, rem);
>  		strcat(buf, buf1);
>  	}
>  
> -	if (!errexit)
> -		SCALEOUT("%s", buf);
> +	SCALEOUT("%s", buf);
>  
> +err:
>  	// This will shutdown everything including us.
>  	if (shutdown) {
>  		shutdown_start = 1;
> -- 
> 2.33.0
> 
> 
>