linux-kernel - Re: [PATCH 2/3] thermal: cpu_cooling: Check OPP for errors

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Date:   Tue, 7 Feb 2017 09:28:15 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Amit Daniel Kachhap <amit.kachhap@...il.com>,
        Javi Merino <javi.merino@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: Re: [PATCH 2/3] thermal: cpu_cooling: Check OPP for errors

On 06-02-17, 13:02, Rafael J. Wysocki wrote:
> On Monday, February 06, 2017 03:56:28 PM Viresh Kumar wrote:
> > It is possible for dev_pm_opp_find_freq_exact() to return errors. It was
> > all fine earlier as dev_pm_opp_get_voltage() had a check within it to
> > check for invalid OPPs, but dev_pm_opp_put() doesn't have any similar
> > checks and the callers need to make sure OPP is valid before calling
> > them.
> > 
> > Also update the later dev_warn_ratelimited() to not print the error
> > message as the OPP is guaranteed to be valid now.
> > 
> > Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> > Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> > ---
> >  drivers/thermal/cpu_cooling.c | 11 +++++++++--
> >  1 file changed, 9 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
> > index 85fdbf762fa0..9534540434e2 100644
> > --- a/drivers/thermal/cpu_cooling.c
> > +++ b/drivers/thermal/cpu_cooling.c
> > @@ -431,13 +431,20 @@ static int get_static_power(struct cpufreq_cooling_device *cpufreq_device,
> >  
> >  	opp = dev_pm_opp_find_freq_exact(cpufreq_device->cpu_dev, freq_hz,
> >  					 true);
> > +	if (IS_ERR(opp)) {
> > +		dev_warn_ratelimited(cpufreq_device->cpu_dev,
> > +				     "Failed to find OPP for frequency %lu: %ld\n",
> > +				     freq_hz, PTR_ERR(opp));
> 
> I'm quite unconvinced about the WARN level of these messages.
> 
> They seem to be mostly useful for the people who provide device trees for
> platforms (ie. system integrators).  If users see them, there is not much
> they can do to fix the problem by themselves and the hardware is OK,
> actually.

Sure. I just wanted to keep it consistent within the function.

-- 
viresh