From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Mon, 13 Jun 2022 20:16:30 +0200
Subject: ACPI: property: Use acpi_dev_for_each_child() for child lookup
Patch-mainline: v6.0-rc1
Git-commit: fa98b3985a4a6de6d40b2469b30a3452575f6acf
References: jsc#PED-1408

Instead of using the list of children of an ACPI device directly,
use acpi_dev_for_each_child() to find the next child of a given
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>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
 drivers/acpi/property.c |   47 +++++++++++++++++++++++++----------------------
 1 file changed, 25 insertions(+), 22 deletions(-)

--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -1012,6 +1012,22 @@ static int acpi_node_prop_read(const str
 				   propname, proptype, val, nval);
 }
 
+static int stop_on_next(struct acpi_device *adev, void *data)
+{
+	struct acpi_device **ret_p = data;
+
+	if (!*ret_p) {
+		*ret_p = adev;
+		return 1;
+	}
+
+	/* Skip until the "previous" object is found. */
+	if (*ret_p == adev)
+		*ret_p = NULL;
+
+	return 0;
+}
+
 /**
  * acpi_get_next_subnode - Return the next child node handle for a fwnode
  * @fwnode: Firmware node to find the next child node for.
@@ -1020,35 +1036,22 @@ static int acpi_node_prop_read(const str
 struct fwnode_handle *acpi_get_next_subnode(const struct fwnode_handle *fwnode,
 					    struct fwnode_handle *child)
 {
-	const struct acpi_device *adev = to_acpi_device_node(fwnode);
-	const struct list_head *head;
-	struct list_head *next;
+	struct acpi_device *adev = to_acpi_device_node(fwnode);
 
 	if ((!child || is_acpi_device_node(child)) && adev) {
-		struct acpi_device *child_adev;
+		struct acpi_device *child_adev = to_acpi_device_node(child);
+
+		acpi_dev_for_each_child(adev, stop_on_next, &child_adev);
+		if (child_adev)
+			return acpi_fwnode_handle(child_adev);
 
-		head = &adev->children;
-		if (list_empty(head))
-			goto nondev;
-
-		if (child) {
-			adev = to_acpi_device_node(child);
-			next = adev->node.next;
-			if (next == head) {
-				child = NULL;
-				goto nondev;
-			}
-			child_adev = list_entry(next, struct acpi_device, node);
-		} else {
-			child_adev = list_first_entry(head, struct acpi_device,
-						      node);
-		}
-		return acpi_fwnode_handle(child_adev);
+		child = NULL;
 	}
 
- nondev:
 	if (!child || is_acpi_data_node(child)) {
 		const struct acpi_data_node *data = to_acpi_data_node(fwnode);
+		const struct list_head *head;
+		struct list_head *next;
 		struct acpi_data_node *dn;
 
 		/*