linux-kernel - Re: [UPDATE][PATCH v3 1/2] cpufreq: intel_pstate: Allow enable/disable energy efficiency

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Date:   Fri, 26 Jun 2020 12:22:55 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        rjw@...ysocki.net, viresh.kumar@...aro.org, lenb@...nel.org,
        dsmythies@...us.net, tglx@...utronix.de, mingo@...hat.com,
        hpa@...or.com, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [UPDATE][PATCH v3 1/2] cpufreq: intel_pstate: Allow
 enable/disable energy efficiency

On Fri, Jun 26, 2020 at 10:49:03AM +0200, Borislav Petkov wrote:
> On Thu, Jun 25, 2020 at 03:49:31PM -0700, Srinivas Pandruvada wrote:
> > +static ssize_t store_energy_efficiency_enable(struct kobject *a,
> > +					      struct kobj_attribute *b,
> > +					      const char *buf, size_t count)
> > +{
> > +	u64 power_ctl;
> > +	u32 input;
> > +	int ret;
> > +
> > +	ret = kstrtouint(buf, 10, &input);
> > +	if (ret)
> > +		return ret;
> > +
> > +	mutex_lock(&intel_pstate_driver_lock);
> > +	rdmsrl(MSR_IA32_POWER_CTL, power_ctl);
> > +	if (input)
> 
> This is too lax - it will be enabled for any !0 value. Please accept
> only 0 and 1.

kstrtobool() ftw