hwmon: (acpi_power_meter) Use acpi_bus_get_acpi_device()

In read_domain_devices(), acpi_bus_get_device() is called to obtain
the ACPI device object attached to the given ACPI handle and
subsequently that object is passed to get_device() for reference
counting, but there is a window between the acpi_bus_get_device()
and get_device() calls in which the ACPI device object in question
may go away.

To address this issue, make read_domain_devices() use
acpi_bus_get_acpi_device() to reference count and return the given
ACPI device object in one go and export that function to modules.

While at it, also make read_domain_devices() and
remove_domain_devices() use acpi_dev_put() instead of calling
put_device() directly on the ACPI device objects returned by
acpi_bus_get_acpi_device().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/11871063.O9o76ZdvQC@kreacher
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 5b54c80..f456ba7 100644 (file)
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -608,6 +608,7 @@ struct acpi_device *acpi_bus_get_acpi_device(acpi_handle handle)
 {
        return handle_to_device(handle, get_acpi_device);
 }
+EXPORT_SYMBOL_GPL(acpi_bus_get_acpi_device);
 
 static struct acpi_device_bus_id *acpi_device_bus_id_match(const char *dev_id)
 {

diff --git a/drivers/hwmon/acpi_power_meter.c b/drivers/hwmon/acpi_power_meter.c
index 014505b..c405a58 100644 (file)
--- a/drivers/hwmon/acpi_power_meter.c
+++ b/drivers/hwmon/acpi_power_meter.c
@@ -535,7 +535,7 @@ static void remove_domain_devices(struct acpi_power_meter_resource *resource)
 
                sysfs_remove_link(resource->holders_dir,
                                  kobject_name(&obj->dev.kobj));
-               put_device(&obj->dev);
+               acpi_dev_put(obj);
        }
 
        kfree(resource->domain_devices);
@@ -597,18 +597,15 @@ static int read_domain_devices(struct acpi_power_meter_resource *resource)
                        continue;
 
                /* Create a symlink to domain objects */
-               resource->domain_devices[i] = NULL;
-               if (acpi_bus_get_device(element->reference.handle,
-                                       &resource->domain_devices[i]))
+               obj = acpi_bus_get_acpi_device(element->reference.handle);
+               resource->domain_devices[i] = obj;
+               if (!obj)
                        continue;
 
-               obj = resource->domain_devices[i];
-               get_device(&obj->dev);
-
                res = sysfs_create_link(resource->holders_dir, &obj->dev.kobj,
                                      kobject_name(&obj->dev.kobj));
                if (res) {
-                       put_device(&obj->dev);
+                       acpi_dev_put(obj);
                        resource->domain_devices[i] = NULL;
                }
        }