Re: [PATCH] cpufreq: Initialize the governor again while restoring policy

[Rafael J. Wysocki]

On Wednesday, July 08, 2015 11:23:58 AM Viresh Kumar wrote:
> When all CPUs of a policy are hot-unplugged, we EXIT the governor but
> don't mark policy->governor as NULL. This was done in order to keep last
> used governor's information intact in sysfs, while the CPUs are offline.
> 
> We also missed marking policy->governor as NULL while restoring the
> policy. Because of that, we call __cpufreq_governor(CPUFREQ_GOV_LIMITS)

How exactly does that happen?

> for an uninitialized policy. Which eventually returns -EBUSY.
> 
> Fix this by setting policy->governor to NULL while restoring the policy.
> 
> Reported-by: Pi-Cheng Chen <pi-cheng.chen@xxxxxxxxxx>
> Reported-by: "Jon Medhurst (Tixy)" <tixy@xxxxxxxxxx>
> Fixes: 18bf3a124ef8 ("cpufreq: Mark policy->governor = NULL for inactive policies")
> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> ---
> For 4.2-rc
> 
>  drivers/cpufreq/cpufreq.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index b612411655f9..2c22e3902e72 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1132,6 +1132,7 @@ static struct cpufreq_policy *cpufreq_policy_restore(unsigned int cpu)
>  
>  		down_write(&policy->rwsem);
>  		policy->cpu = cpu;
> +		policy->governor = NULL;
>  		up_write(&policy->rwsem);
>  	}
>  
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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