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

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Date:   Sun, 24 Oct 2021 21:34:05 +0800
From:   "Li, Zhijian" <lizhijian@...fujitsu.com>
To:     <paulmck@...nel.org>
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 2021/10/23 7:10, Paul E. McKenney wrote:
> 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.

It sounds pretty good, i will update it later.

Thanks
Zhijian


> 							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
>>
>>
>>
>