platform/x86/thinkpad_acpi: Use acpi_dev_for_each_child()
authorRafael J. Wysocki <rafael.j.wysocki@intel.com>
Mon, 13 Jun 2022 18:30:19 +0000 (20:30 +0200)
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tue, 21 Jun 2022 12:34:52 +0000 (14:34 +0200)
Instead of walking the list of children of an ACPI device directly,
use acpi_dev_for_each_child() to carry out an action for all of
the given ACPI device's children.

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>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
drivers/platform/x86/thinkpad_acpi.c

index e6cb4a14cdd4705cb479e4e21b52dbf3d472dda1..242542db644a3e4402d9d3f7c17ba2084ff82a5a 100644 (file)
@@ -6841,6 +6841,31 @@ static const struct backlight_ops ibm_backlight_data = {
 
 /* --------------------------------------------------------------------- */
 
+static int __init tpacpi_evaluate_bcl(struct acpi_device *adev, void *not_used)
+{
+       struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+       union acpi_object *obj;
+       acpi_status status;
+       int rc;
+
+       status = acpi_evaluate_object(adev->handle, "_BCL", NULL, &buffer);
+       if (ACPI_FAILURE(status))
+               return 0;
+
+       obj = buffer.pointer;
+       if (!obj || obj->type != ACPI_TYPE_PACKAGE) {
+               acpi_handle_info(adev->handle,
+                                "Unknown _BCL data, please report this to %s\n",
+                                TPACPI_MAIL);
+               rc = 0;
+       } else {
+               rc = obj->package.count;
+       }
+       kfree(obj);
+
+       return rc;
+}
+
 /*
  * Call _BCL method of video device.  On some ThinkPads this will
  * switch the firmware to the ACPI brightness control mode.
@@ -6848,37 +6873,13 @@ static const struct backlight_ops ibm_backlight_data = {
 
 static int __init tpacpi_query_bcl_levels(acpi_handle handle)
 {
-       struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
-       union acpi_object *obj;
-       struct acpi_device *device, *child;
-       int rc;
+       struct acpi_device *device;
 
        device = acpi_fetch_acpi_dev(handle);
        if (!device)
                return 0;
 
-       rc = 0;
-       list_for_each_entry(child, &device->children, node) {
-               acpi_status status = acpi_evaluate_object(child->handle, "_BCL",
-                                                         NULL, &buffer);
-               if (ACPI_FAILURE(status)) {
-                       buffer.length = ACPI_ALLOCATE_BUFFER;
-                       continue;
-               }
-
-               obj = (union acpi_object *)buffer.pointer;
-               if (!obj || (obj->type != ACPI_TYPE_PACKAGE)) {
-                       pr_err("Unknown _BCL data, please report this to %s\n",
-                               TPACPI_MAIL);
-                       rc = 0;
-               } else {
-                       rc = obj->package.count;
-               }
-               break;
-       }
-
-       kfree(buffer.pointer);
-       return rc;
+       return acpi_dev_for_each_child(device, tpacpi_evaluate_bcl, NULL);
 }