ACPI: glue: Introduce acpi_dev_has_children()

Define acpi_dev_has_children() as a wrapper around
acpi_dev_for_each_child() and use it to check if the given ACPI
device has any children instead of checking the children list
head in struct acpi_device.

This will help to eliminate the children list head from struct
acpi_device as it is redundant and it is used in questionable ways
in some places (in particular, locking is needed for walking the
list pointed to it safely, but it is often missing).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
index 552d82dfa476b87866bbf69c0b1534a89c2c57be..5203a7c60daa951bec8250b2beaa5f134a6a1c10 100644 (file)
--- a/drivers/acpi/glue.c
+++ b/drivers/acpi/glue.c
@@ -77,12 +77,22 @@ static struct acpi_bus_type *acpi_get_bus_type(struct device *dev)
 #define FIND_CHILD_MIN_SCORE   1
 #define FIND_CHILD_MAX_SCORE   2
 
+static int match_any(struct acpi_device *adev, void *not_used)
+{
+       return 1;
+}
+
+static bool acpi_dev_has_children(struct acpi_device *adev)
+{
+       return acpi_dev_for_each_child(adev, match_any, NULL) > 0;
+}
+
 static int find_child_checks(struct acpi_device *adev, bool check_children)
 {
        unsigned long long sta;
        acpi_status status;
 
-       if (check_children && list_empty(&adev->children))
+       if (check_children && !acpi_dev_has_children(adev))
                return -ENODEV;
 
        status = acpi_evaluate_integer(adev->handle, "_STA", NULL, &sta);