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Commit dcb84f33 authored by Venkatesh Pallipadi's avatar Venkatesh Pallipadi Committed by Len Brown
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cpuidle acpi driver: fix oops on AC<->DC 

cpuidle and acpi driver interaction bug with the way cpuidle_register_driver()
is called. Due to this bug, there will be oops on
AC<->DC on some systems, where they support C-states in one DC and not in AC.

The current code does
ON BOOT:
	Look at CST and other C-state info to see whether more than C1 is
	supported. If it is, then acpi processor_idle does a
	cpuidle_register_driver() call, which internally enables the device.

ON CST change notification (AC<->DC) and on suspend-resume:
	acpi driver temporarily disables device, updates the device with
	any new C-states, and reenables the device.

The problem is is on boot, there are no C2, C3 states supported and we skip
the register. Later on AC<->DC, we may get a CST notification and we try
to reevaluate CST and enabled the device, without actually registering it.
This causes breakage as we try to create /sys fs sub directory, without the
parent directory which is created at register time.

Thanks to Sanjeev for reporting the problem here.
http://bugzilla.kernel.org/show_bug.cgi?id=10394



Signed-off-by: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent e1094bfa

drivers/acpi/processor_idle.c

+7 −6
Original line number Diff line number Diff line
@@ -1669,6 +1669,7 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr) 
		return -EINVAL;

	}



	dev->cpu = pr->id;

	for (i = 0; i < CPUIDLE_STATE_MAX; i++) {

		dev->states[i].name[0] = '\0';

		dev->states[i].desc[0] = '\0';
@@ -1738,7 +1739,7 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr) 


int acpi_processor_cst_has_changed(struct acpi_processor *pr)

{

	int ret;

	int ret = 0;



	if (boot_option_idle_override)

		return 0;
@@ -1756,8 +1757,10 @@ int acpi_processor_cst_has_changed(struct acpi_processor *pr) 
	cpuidle_pause_and_lock();

	cpuidle_disable_device(&pr->power.dev);

	acpi_processor_get_power_info(pr);

	if (pr->flags.power) {

		acpi_processor_setup_cpuidle(pr);

		ret = cpuidle_enable_device(&pr->power.dev);

	}

	cpuidle_resume_and_unlock();



	return ret;
@@ -1813,7 +1816,6 @@ int __cpuinit acpi_processor_power_init(struct acpi_processor *pr, 
	if (pr->flags.power) {

#ifdef CONFIG_CPU_IDLE

		acpi_processor_setup_cpuidle(pr);

		pr->power.dev.cpu = pr->id;

		if (cpuidle_register_device(&pr->power.dev))

			return -EIO;

#endif
@@ -1850,7 +1852,6 @@ int acpi_processor_power_exit(struct acpi_processor *pr, 
		return 0;



#ifdef CONFIG_CPU_IDLE

	if (pr->flags.power)

	cpuidle_unregister_device(&pr->power.dev);

#endif

	pr->flags.power_setup_done = 0;

drivers/cpuidle/cpuidle.c

+35 −5
Original line number Diff line number Diff line
@@ -38,6 +38,8 @@ static void cpuidle_kick_cpus(void) 
static void cpuidle_kick_cpus(void) {}

#endif



static int __cpuidle_register_device(struct cpuidle_device *dev);



/**

 * cpuidle_idle_call - the main idle loop

 *
@@ -138,6 +140,12 @@ int cpuidle_enable_device(struct cpuidle_device *dev) 
	if (!dev->state_count)

		return -EINVAL;



	if (dev->registered == 0) {

		ret = __cpuidle_register_device(dev);

		if (ret)

			return ret;

	}



	if ((ret = cpuidle_add_state_sysfs(dev)))

		return ret;
@@ -232,10 +240,13 @@ static void poll_idle_init(struct cpuidle_device *dev) {} 
#endif /* CONFIG_ARCH_HAS_CPU_RELAX */



/**

 * cpuidle_register_device - registers a CPU's idle PM feature

 * __cpuidle_register_device - internal register function called before register

 * and enable routines

 * @dev: the cpu

 *

 * cpuidle_lock mutex must be held before this is called

 */

int cpuidle_register_device(struct cpuidle_device *dev)

static int __cpuidle_register_device(struct cpuidle_device *dev)

{

	int ret;

	struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
@@ -247,18 +258,34 @@ int cpuidle_register_device(struct cpuidle_device *dev) 


	init_completion(&dev->kobj_unregister);



	mutex_lock(&cpuidle_lock);



	poll_idle_init(dev);



	per_cpu(cpuidle_devices, dev->cpu) = dev;

	list_add(&dev->device_list, &cpuidle_detected_devices);

	if ((ret = cpuidle_add_sysfs(sys_dev))) {

		mutex_unlock(&cpuidle_lock);

		module_put(cpuidle_curr_driver->owner);

		return ret;

	}



	dev->registered = 1;

	return 0;

}



/**

 * cpuidle_register_device - registers a CPU's idle PM feature

 * @dev: the cpu

 */

int cpuidle_register_device(struct cpuidle_device *dev)

{

	int ret;



	mutex_lock(&cpuidle_lock);



	if ((ret = __cpuidle_register_device(dev))) {

		mutex_unlock(&cpuidle_lock);

		return ret;

	}



	cpuidle_enable_device(dev);

	cpuidle_install_idle_handler();
@@ -278,6 +305,9 @@ void cpuidle_unregister_device(struct cpuidle_device *dev) 
{

	struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);



	if (dev->registered == 0)

		return;



	cpuidle_pause_and_lock();



	cpuidle_disable_device(dev);

include/linux/cpuidle.h

+1 −0
Original line number Diff line number Diff line
@@ -82,6 +82,7 @@ struct cpuidle_state_kobj { 
};



struct cpuidle_device {

	unsigned int		registered:1;

	unsigned int		enabled:1;

	unsigned int		cpu;