cpufreq: qcom-cpufreq-hw: Avoid stack buffer for IRQ name

Registering an IRQ requires the string buffer containing the name to
remain allocated, as the name is not copied into another buffer.

So let's add a irq_name field to the data struct instead, which is
guaranteed to have the appropriate lifetime.

Cc: Thara Gopinath <thara.gopinath@linaro.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Andy Gross <agross@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Thara Gopinath <thara.gopinath@linaro.org>
Tested-by: Steev Klimaszewski <steev@kali.org>
Signed-off-by: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/cpufreq/qcom-cpufreq-hw.c

@@ -46,6 +46,7 @@ struct qcom_cpufreq_data {
 	 */
 	struct mutex throttle_lock;
 	int throttle_irq;
+	char irq_name[15];
 	bool cancel_throttle;
 	struct delayed_work throttle_work;
 	struct cpufreq_policy *policy;
@@ -367,7 +368,6 @@ static int qcom_cpufreq_hw_lmh_init(struct cpufreq_policy *policy, int index)
 {
 	struct qcom_cpufreq_data *data = policy->driver_data;
 	struct platform_device *pdev = cpufreq_get_driver_data();
-	char irq_name[15];
 	int ret;
 
 	/*
@@ -384,11 +384,11 @@ static int qcom_cpufreq_hw_lmh_init(struct cpufreq_policy *policy, int index)
 	mutex_init(&data->throttle_lock);
 	INIT_DEFERRABLE_WORK(&data->throttle_work, qcom_lmh_dcvs_poll);
 
-	snprintf(irq_name, sizeof(irq_name), "dcvsh-irq-%u", policy->cpu);
+	snprintf(data->irq_name, sizeof(data->irq_name), "dcvsh-irq-%u", policy->cpu);
 	ret = request_threaded_irq(data->throttle_irq, NULL, qcom_lmh_dcvs_handle_irq,
-				   IRQF_ONESHOT, irq_name, data);
+				   IRQF_ONESHOT, data->irq_name, data);
 	if (ret) {
-		dev_err(&pdev->dev, "Error registering %s: %d\n", irq_name, ret);
+		dev_err(&pdev->dev, "Error registering %s: %d\n", data->irq_name, ret);
 		return 0;
 	}