linux-kernel - Re: [PATCH RESEND] timer stats: reset entries when disable the timer usage statistics

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Date:	Wed, 09 Oct 2013 21:04:48 -0700
From:	John Stultz <john.stultz@...aro.org>
To:	Dong Zhu <bluezhudong@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>
CC:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND] timer stats: reset entries when disable the timer
 usage statistics

On 10/09/2013 07:59 PM, Dong Zhu wrote:
> From f41628c61d8a9172677ba33a55b61e37ce28f7a6 Mon Sep 17 00:00:00 2001
> From: Dong Zhu <bluezhudong@...il.com> 
> Date: Thu, 10 Oct 2013 10:38:13 +0800
>
> When we stop timer statistics collection (via echo 0 >
> /proc/timers_stats), the statistics data is still exported as if it were
> correct, which can cause applicaitons to misuse the statistics.
>
> This patch resets the statistics when we stop collecting them, to avoid
> this problem.
>
> Signed-off-by: Dong Zhu <bluezhudong@...il.com>
> ---
>  kernel/time/timer_stats.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/kernel/time/timer_stats.c b/kernel/time/timer_stats.c
> index 0b537f2..43f05e7 100644
> --- a/kernel/time/timer_stats.c
> +++ b/kernel/time/timer_stats.c
> @@ -371,6 +371,7 @@ static ssize_t tstats_write(struct file *file, const char __user *buf,
>  	switch (ctl[0]) {
>  	case '0':
>  		if (timer_stats_active) {
> +			reset_entries();
>  			timer_stats_active = 0;
>  			time_stop = ktime_get();
>  			sync_access();

This looks ok to me. Thomas, do you have any objections here?

thanks
-john

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