[PATCH v1] ACPI: battery: Drop redundant locking

[PATCH v1] ACPI: battery: Drop redundant locking

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

All of the evaluations of objects in the ACPI namespace are carried out
under the namespace lock and interpreter lock in ACPICA, so it is not
necessary to put any additional locks around them for synchronization.

However, the ACPI battery driver does just that, so remove the
redundant locking around ACPI object evaluation from it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/battery.c |   12 ------------
 1 file changed, 12 deletions(-)

--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -91,7 +91,6 @@ enum {
 };
 
 struct acpi_battery {
-	struct mutex lock;
 	struct mutex update_lock;
 	struct power_supply *bat;
 	struct power_supply_desc bat_desc;
@@ -535,11 +534,9 @@ static int acpi_battery_get_info(struct
 		struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 		acpi_status status = AE_ERROR;
 
-		mutex_lock(&battery->lock);
 		status = acpi_evaluate_object(battery->device->handle,
 					      use_bix ? "_BIX":"_BIF",
 					      NULL, &buffer);
-		mutex_unlock(&battery->lock);
 
 		if (ACPI_FAILURE(status)) {
 			acpi_handle_info(battery->device->handle,
@@ -576,11 +573,8 @@ static int acpi_battery_get_state(struct
 			msecs_to_jiffies(cache_time)))
 		return 0;
 
-	mutex_lock(&battery->lock);
 	status = acpi_evaluate_object(battery->device->handle, "_BST",
 				      NULL, &buffer);
-	mutex_unlock(&battery->lock);
-
 	if (ACPI_FAILURE(status)) {
 		acpi_handle_info(battery->device->handle,
 				 "_BST evaluation failed: %s",
@@ -628,11 +622,8 @@ static int acpi_battery_set_alarm(struct
 	    !test_bit(ACPI_BATTERY_ALARM_PRESENT, &battery->flags))
 		return -ENODEV;
 
-	mutex_lock(&battery->lock);
 	status = acpi_execute_simple_method(battery->device->handle, "_BTP",
 					    battery->alarm);
-	mutex_unlock(&battery->lock);
-
 	if (ACPI_FAILURE(status))
 		return -ENODEV;
 
@@ -1235,9 +1226,6 @@ static int acpi_battery_add(struct acpi_
 	strscpy(acpi_device_name(device), ACPI_BATTERY_DEVICE_NAME);
 	strscpy(acpi_device_class(device), ACPI_BATTERY_CLASS);
 	device->driver_data = battery;
-	result = devm_mutex_init(&device->dev, &battery->lock);
-	if (result)
-		return result;
 
 	result = devm_mutex_init(&device->dev, &battery->update_lock);
 	if (result)