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Commit 40bf66ec authored by Lin Ming's avatar Lin Ming Committed by Rafael J. Wysocki
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ACPI / PM: Fix resource_lock dead lock in acpi_power_on_device 



Commit 0090def6("ACPI: Add interface to register/unregister device
to/from power resources") used resource_lock to protect the devices list
that relies on power resource. It caused a mutex dead lock, as below

    acpi_power_on ---> lock resource_lock
      __acpi_power_on
        acpi_power_on_device
          acpi_power_get_inferred_state
            acpi_power_get_list_state ---> lock resource_lock

This patch adds a new mutex "devices_lock" to protect the devices list
and calls acpi_power_on_device in acpi_power_on, instead of
__acpi_power_on, after the resource_lock is released.

[rjw: Changed data type of a boolean variable to bool.]

Signed-off-by: default avatarLin Ming <ming.m.lin@intel.com>
Signed-off-by: default avatarAaron Lu <aaron.lu@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
parent 8f7412a7

drivers/acpi/power.c

+23 −11
Original line number Diff line number Diff line
@@ -107,6 +107,7 @@ struct acpi_power_resource { 


	/* List of devices relying on this power resource */

	struct acpi_power_resource_device *devices;

	struct mutex devices_lock;

};



static struct list_head acpi_power_resource_list;
@@ -225,7 +226,6 @@ static void acpi_power_on_device(struct acpi_power_managed_device *device) 


static int __acpi_power_on(struct acpi_power_resource *resource)

{

	struct acpi_power_resource_device *device_list = resource->devices;

	acpi_status status = AE_OK;



	status = acpi_evaluate_object(resource->device->handle, "_ON", NULL, NULL);
@@ -238,19 +238,15 @@ static int __acpi_power_on(struct acpi_power_resource *resource) 
	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Power resource [%s] turned on\n",

			  resource->name));



	while (device_list) {

		acpi_power_on_device(device_list->device);



		device_list = device_list->next;

	}



	return 0;

}



static int acpi_power_on(acpi_handle handle)

{

	int result = 0;

	bool resume_device = false;

	struct acpi_power_resource *resource = NULL;

	struct acpi_power_resource_device *device_list;



	result = acpi_power_get_context(handle, &resource);

	if (result)
@@ -266,10 +262,25 @@ static int acpi_power_on(acpi_handle handle) 
		result = __acpi_power_on(resource);

		if (result)

			resource->ref_count--;

		else

			resume_device = true;

	}



	mutex_unlock(&resource->resource_lock);



	if (!resume_device)

		return result;



	mutex_lock(&resource->devices_lock);



	device_list = resource->devices;

	while (device_list) {

		acpi_power_on_device(device_list->device);

		device_list = device_list->next;

	}



	mutex_unlock(&resource->devices_lock);



	return result;

}
@@ -355,7 +366,7 @@ static void __acpi_power_resource_unregister_device(struct device *dev, 
	if (acpi_power_get_context(res_handle, &resource))

		return;



	mutex_lock(&resource->resource_lock);

	mutex_lock(&resource->devices_lock);

	prev = NULL;

	curr = resource->devices;

	while (curr) {
@@ -372,7 +383,7 @@ static void __acpi_power_resource_unregister_device(struct device *dev, 
		prev = curr;

		curr = curr->next;

	}

	mutex_unlock(&resource->resource_lock);

	mutex_unlock(&resource->devices_lock);

}



/* Unlink dev from all power resources in _PR0 */
@@ -414,10 +425,10 @@ static int __acpi_power_resource_register_device( 


	power_resource_device->device = powered_device;



	mutex_lock(&resource->resource_lock);

	mutex_lock(&resource->devices_lock);

	power_resource_device->next = resource->devices;

	resource->devices = power_resource_device;

	mutex_unlock(&resource->resource_lock);

	mutex_unlock(&resource->devices_lock);



	return 0;

}
@@ -721,6 +732,7 @@ static int acpi_power_add(struct acpi_device *device) 


	resource->device = device;

	mutex_init(&resource->resource_lock);

	mutex_init(&resource->devices_lock);

	strcpy(resource->name, device->pnp.bus_id);

	strcpy(acpi_device_name(device), ACPI_POWER_DEVICE_NAME);

	strcpy(acpi_device_class(device), ACPI_POWER_CLASS);