linux-kernel - Re: [PATCH 5/6] leds: Use all-in-one vtime aware kcpustat accessor

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Date:   Thu, 21 Nov 2019 07:58:26 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Frederic Weisbecker <frederic@...nel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Rik van Riel <riel@...riel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Yauheni Kaliuta <yauheni.kaliuta@...hat.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Pavel Machek <pavel@....cz>
Subject: Re: [PATCH 5/6] leds: Use all-in-one vtime aware kcpustat accessor


* Frederic Weisbecker <frederic@...nel.org> wrote:

> We can now safely read user kcpustat fields on nohz_full CPUs.
> Use the appropriate accessor.
> 
> Reported-by: Yauheni Kaliuta <yauheni.kaliuta@...hat.com>
> Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
> Cc: Jacek Anaszewski <jacek.anaszewski@...il.com>
> Cc: Pavel Machek <pavel@....cz>
> Cc: Yauheni Kaliuta <yauheni.kaliuta@...hat.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Rik van Riel <riel@...riel.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Wanpeng Li <wanpengli@...cent.com>
> Cc: Ingo Molnar <mingo@...nel.org>
> ---
>  drivers/leds/trigger/ledtrig-activity.c | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/leds/trigger/ledtrig-activity.c b/drivers/leds/trigger/ledtrig-activity.c
> index ddfc5edd07c8..6901e3631c22 100644
> --- a/drivers/leds/trigger/ledtrig-activity.c
> +++ b/drivers/leds/trigger/ledtrig-activity.c
> @@ -57,11 +57,15 @@ static void led_activity_function(struct timer_list *t)
>  	curr_used = 0;
>  
>  	for_each_possible_cpu(i) {
> -		curr_used += kcpustat_cpu(i).cpustat[CPUTIME_USER]
> -			  +  kcpustat_cpu(i).cpustat[CPUTIME_NICE]
> -			  +  kcpustat_field(&kcpustat_cpu(i), CPUTIME_SYSTEM, i)
> -			  +  kcpustat_cpu(i).cpustat[CPUTIME_SOFTIRQ]
> -			  +  kcpustat_cpu(i).cpustat[CPUTIME_IRQ];
> +		struct kernel_cpustat kcpustat;
> +
> +		kcpustat_fetch_cpu(&kcpustat, i);
> +
> +		curr_used += kcpustat.cpustat[CPUTIME_USER]
> +			  +  kcpustat.cpustat[CPUTIME_NICE]
> +			  +  kcpustat.cpustat[CPUTIME_SYSTEM]
> +			  +  kcpustat.cpustat[CPUTIME_SOFTIRQ]
> +			  +  kcpustat.cpustat[CPUTIME_IRQ];

Not the best tested series:

--- a/drivers/leds/trigger/ledtrig-activity.c
+++ b/drivers/leds/trigger/ledtrig-activity.c
@@ -59,7 +59,7 @@ static void led_activity_function(struct timer_list *t)
 	for_each_possible_cpu(i) {
 		struct kernel_cpustat kcpustat;
 
-		kcpustat_fetch_cpu(&kcpustat, i);
+		kcpustat_cpu_fetch(&kcpustat, i);
 
 		curr_used += kcpustat.cpustat[CPUTIME_USER]
 			  +  kcpustat.cpustat[CPUTIME_NICE]


:-)

Thanks,

	Ingo