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

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Message-ID: <20160125163720.GE3322@vireshk>
Date:	Mon, 25 Jan 2016 22:07:20 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	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 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>

-- 
viresh