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

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Message-ID: <CAOh2x==kSnXWZMhrEcRyiVc-5iixecQki5-7ZC-ajes-D48-sA@mail.gmail.com>
Date:	Wed, 19 Aug 2015 13:54:17 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Vaishali Thakkar <vthakkar1994@...il.com>
Cc:	Zhang Rui <rui.zhang@...el.com>,
	Eduardo Valentin <edubezval@...il.com>,
	Linux PM list <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] thermal: cpu_cooling: Remove usage of devm functions

On Wed, Aug 19, 2015 at 11:52 AM, Vaishali Thakkar
<vthakkar1994@...il.com> 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@...il.com>
> ---
> 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);
        }

        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;
 }
--
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