Re: [PATCH] thermal: cpu_cooling: Remove usage of devm functions

From: Vaishali Thakkar
Date: Wed Aug 19 2015 - 07:58:03 EST


On Wed, Aug 19, 2015 at 1:54 PM, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
> On Wed, Aug 19, 2015 at 11:52 AM, Vaishali Thakkar
> <vthakkar1994@xxxxxxxxx> wrote:
>> In the function cpufreq_get_requested_power, the memory allocated
>> for load_cpu is live within the function only. And after the
>> allocation it is immediately freed with devm_kfree. There is no
>> need to allocate memory for load_cpu with devm function so replace
>> devm_kcalloc with kcalloc and devm_kfree with kfree.
>>
>> Signed-off-by: Vaishali Thakkar <vthakkar1994@xxxxxxxxx>
>> ---
>> This patch is having one checkpatch.pl warning which suggests that
>> kfree(NULL) is safe. But I think leaving code with if is nice
>> because it reflects the fact that kcalloc was under an if. So, I
>> have ignored checkpatch. If maintainer wants me to go for changing
>> things, I am fine with it too.
>
> I will rather ask you to do this:
>
> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
> index 620dcd405ff6..a04055ea5d94 100644
> --- a/drivers/thermal/cpu_cooling.c
> +++ b/drivers/thermal/cpu_cooling.c
> @@ -584,8 +584,8 @@ static int cpufreq_get_requested_power(struct
> thermal_cooling_device *cdev,
> if (trace_thermal_power_cpu_get_power_enabled()) {
> u32 ncpus = cpumask_weight(&cpufreq_device->allowed_cpus);
>
> - load_cpu = devm_kcalloc(&cdev->device, ncpus, sizeof(*load_cpu),
> - GFP_KERNEL);
> + load_cpu = kcalloc(&cdev->device, ncpus, sizeof(*load_cpu),
> + GFP_KERNEL);
> }

Sorry. I forgot to ask you one more thing. devm_kcalloc takes one more
argument then
kcalloc. So, the change I did is correct I guess. And I'm not sure why
you suggested this
change? I assume you just want me to correct in my patch for last
argument. But that line
also comes under 80 characters.

> for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
> @@ -607,22 +607,20 @@ static int cpufreq_get_requested_power(struct
> thermal_cooling_device *cdev,
>
> dynamic_power = get_dynamic_power(cpufreq_device, freq);
> ret = get_static_power(cpufreq_device, tz, freq, &static_power);
> - if (ret) {
> - if (load_cpu)
> - devm_kfree(&cdev->device, load_cpu);
> - return ret;
> - }
> + if (ret)
> + goto free;
>
> - if (load_cpu) {
> + if (load_cpu)
> trace_thermal_power_cpu_get_power(
> &cpufreq_device->allowed_cpus,
> freq, load_cpu, i, dynamic_power, static_power);
>
> - devm_kfree(&cdev->device, load_cpu);
> - }
> -
> *power = static_power + dynamic_power;
> - return 0;
> +
> +free:
> + kfree(&cdev->device, load_cpu);
> +
> + return ret;
> }



--
Vaishali
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