Re: [PATCH v2] thermal: cpu_cooling: Remove usage of devm functions

Javi Merino
2015-08-26T12:47:36Z

I missed this because I wasn't CCed :( Thankfully, I'll be in
MAINTAINERS for this soon.

On Thu, Aug 20, 2015 at 05:14:02PM +0100, Vaishali Thakkar 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@gmail.com>
> ---
> Changes since v1:
> - Introduce new label based on Viresh Kumar's suggestion
> ---
> drivers/thermal/cpu_cooling.c | 20 +++++++++-----------
> 1 file changed, 9 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
> index 620dcd4..7027923 100644
> --- a/drivers/thermal/cpu_cooling.c
> +++ b/drivers/thermal/cpu_cooling.c
> @@ -584,8 +584,7 @@ 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(ncpus, sizeof(*load_cpu), GFP_KERNEL);
> }
>
> for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
> @@ -607,22 +606,21 @@ 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);

This introduces a memory leak. Keep the kfree() here, you can't drop
it. Cheers,
Javi

> - }
> -
> *power = static_power + dynamic_power;
> return 0;
> +
> +free:
> + kfree(load_cpu);
> +
> + return ret;
> }
>
> /**