ACPI: processor: Do not expose global variable acpi_idle_driver

Move the cpuidle driver check from __acpi_processor_start() to
acpi_processor_power_init() which allows variable acpi_idle_driver to
become static.

No intentional functional impact.

Signed-off-by: Huisong Li <lihuisong@huawei.com>
Link: https://patch.msgid.link/20250923032428.2656329-2-lihuisong@huawei.com
[ rjw: Subject tweak, new changelog, adjustment of a new comment ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: LiHuiSong1

drivers/acpi/processor_driver.c

@@ -166,8 +166,7 @@ static int __acpi_processor_start(struct acpi_device *device)
 	if (result && !IS_ENABLED(CONFIG_ACPI_CPU_FREQ_PSS))
 		dev_dbg(&device->dev, "CPPC data invalid or not present\n");
 
-	if (cpuidle_get_driver() == &acpi_idle_driver)
-		acpi_processor_power_init(pr);
+	acpi_processor_power_init(pr);
 
 	acpi_pss_perf_init(pr);
 

drivers/acpi/processor_idle.c

@@ -51,7 +51,7 @@ module_param(latency_factor, uint, 0644);
 
 static DEFINE_PER_CPU(struct cpuidle_device *, acpi_cpuidle_device);
 
-struct cpuidle_driver acpi_idle_driver = {
+static struct cpuidle_driver acpi_idle_driver = {
 	.name =		"acpi_idle",
 	.owner =	THIS_MODULE,
 };
@@ -1404,6 +1404,13 @@ void acpi_processor_power_init(struct acpi_processor *pr)
 {
 	struct cpuidle_device *dev;
 
+	/*
+	 * The code below only works if the current cpuidle driver is the ACPI
+	 * idle driver.
+	 */
+	if (cpuidle_get_driver() != &acpi_idle_driver)
+		return;
+
 	if (disabled_by_idle_boot_param())
 		return;
 

include/acpi/processor.h

@@ -417,7 +417,6 @@ static inline void acpi_processor_throttling_init(void) {}
 #endif	/* CONFIG_ACPI_CPU_FREQ_PSS */
 
 /* in processor_idle.c */
-extern struct cpuidle_driver acpi_idle_driver;
 #ifdef CONFIG_ACPI_PROCESSOR_IDLE
 void acpi_processor_power_init(struct acpi_processor *pr);
 void acpi_processor_power_exit(struct acpi_processor *pr);