linux-kernel - Re: [PATCH] cpufreq: cpufreq-dt: avoid uninitialized variable warnings:

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Date:	Wed, 27 Jan 2016 23:56:39 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	Arnd Bergmann <arnd@...db.de>,
	linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpufreq: cpufreq-dt: avoid uninitialized variable warnings:

On Monday, January 25, 2016 10:07:20 PM Viresh Kumar wrote:
> On 25-01-16, 16:45, Arnd Bergmann wrote:
> > gcc warns quite a bit about values returned from allocate_resources()
> > in cpufreq-dt.c:
> > 
> > cpufreq-dt.c: In function 'cpufreq_init':
> > cpufreq-dt.c:327:6: error: 'cpu_dev' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> > cpufreq-dt.c:197:17: note: 'cpu_dev' was declared here
> > cpufreq-dt.c:376:2: error: 'cpu_clk' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> > cpufreq-dt.c:199:14: note: 'cpu_clk' was declared here
> > cpufreq-dt.c: In function 'dt_cpufreq_probe':
> > cpufreq-dt.c:461:2: error: 'cpu_clk' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> > cpufreq-dt.c:447:14: note: 'cpu_clk' was declared here
> > 
> > The problem is that it's slightly hard for gcc to follow return
> > codes across PTR_ERR() calls.
> > This patch uses explicit assignments to the "ret" variable to make
> > it easier for gcc to verify that the code is actually correct,
> > without the need to add a bogus initialization.
> > 
> > Signed-off-by: Arnd Bergmann <arnd@...db.de>
> > ---
> >  drivers/cpufreq/cpufreq-dt.c | 15 +++++++--------
> >  1 file changed, 7 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
> > index 9bc37c437874..0ca74d070058 100644
> > --- a/drivers/cpufreq/cpufreq-dt.c
> > +++ b/drivers/cpufreq/cpufreq-dt.c
> > @@ -142,15 +142,16 @@ static int allocate_resources(int cpu, struct device **cdev,
> >  
> >  try_again:
> >  	cpu_reg = regulator_get_optional(cpu_dev, reg);
> > -	if (IS_ERR(cpu_reg)) {
> > +	ret = PTR_ERR_OR_ZERO(cpu_reg);
> > +	if (ret) {
> >  		/*
> >  		 * If cpu's regulator supply node is present, but regulator is
> >  		 * not yet registered, we should try defering probe.
> >  		 */
> > -		if (PTR_ERR(cpu_reg) == -EPROBE_DEFER) {
> > +		if (ret == -EPROBE_DEFER) {
> >  			dev_dbg(cpu_dev, "cpu%d regulator not ready, retry\n",
> >  				cpu);
> > -			return -EPROBE_DEFER;
> > +			return ret;
> >  		}
> >  
> >  		/* Try with "cpu-supply" */
> > @@ -159,18 +160,16 @@ try_again:
> >  			goto try_again;
> >  		}
> >  
> > -		dev_dbg(cpu_dev, "no regulator for cpu%d: %ld\n",
> > -			cpu, PTR_ERR(cpu_reg));
> > +		dev_dbg(cpu_dev, "no regulator for cpu%d: %d\n", cpu, ret);
> >  	}
> >  
> >  	cpu_clk = clk_get(cpu_dev, NULL);
> > -	if (IS_ERR(cpu_clk)) {
> > +	ret = PTR_ERR_OR_ZERO(cpu_clk);
> > +	if (ret) {
> >  		/* put regulator */
> >  		if (!IS_ERR(cpu_reg))
> >  			regulator_put(cpu_reg);
> >  
> > -		ret = PTR_ERR(cpu_clk);
> > -
> >  		/*
> >  		 * If cpu's clk node is present, but clock is not yet
> >  		 * registered, we should try defering probe.
> 
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

Applied, thanks!

Rafael