[PATCH v2 4/5] ACPI: property: Do not pass NULL handles to acpi_attach_data()

["Rafael J. Wysocki" <rafael@kernel.org>]

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

In certain circumstances, the ACPI handle of a data-only node may be
NULL, in which case it does not make sense to attempt to attach that
node to an ACPI namespace object, so update the code to avoid attempts
to do so.

This prevents confusing and unuseful error messages from being printed.

Also document the fact that the ACPI handle of a data-only node may be
NULL and when that happens in a code comment.  In addition, make
acpi_add_nondev_subnodes() print a diagnostic message for each data-only
node with an unknown ACPI namespace scope.

Fixes: 1d52f10917a7 ("ACPI: property: Tie data nodes to acpi handles")
Cc: 6.0+ <stable@vger.kernel.org> # 6.0+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v1 -> v2:
   * Previously [3/4]
   * Rebase on top of new [2-3/5]
   * Reformat the "unknown scope" message and downgrade it to "debug" (it
     may not indicate any functional issue)

---
 drivers/acpi/property.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -124,6 +124,10 @@ static bool acpi_nondev_subnode_extract(
 		result = true;
 
 	if (result) {
+		/*
+		 * This will be NULL if the desc package is embedded in an outer
+		 * _DSD-equivalent package and its scope cannot be determined.
+		 */
 		dn->handle = handle;
 		dn->data.pointer = desc;
 		list_add_tail(&dn->sibling, list);
@@ -224,6 +228,8 @@ static bool acpi_add_nondev_subnodes(acp
 			 * strings because there is no way to build full
 			 * pathnames out of them.
 			 */
+			acpi_handle_debug(scope, "subnode %s: Unknown scope\n",
+					  link->package.elements[0].string.pointer);
 			desc = &link->package.elements[1];
 			result = acpi_nondev_subnode_extract(desc, NULL, link,
 							     list, parent);
@@ -396,6 +402,9 @@ static void acpi_untie_nondev_subnodes(s
 	struct acpi_data_node *dn;
 
 	list_for_each_entry(dn, &data->subnodes, sibling) {
+		if (!dn->handle)
+			continue;
+
 		acpi_detach_data(dn->handle, acpi_nondev_subnode_tag);
 
 		acpi_untie_nondev_subnodes(&dn->data);
@@ -410,6 +419,9 @@ static bool acpi_tie_nondev_subnodes(str
 		acpi_status status;
 		bool ret;
 
+		if (!dn->handle)
+			continue;
+
 		status = acpi_attach_data(dn->handle, acpi_nondev_subnode_tag, dn);
 		if (ACPI_FAILURE(status) && status != AE_ALREADY_EXISTS) {
 			acpi_handle_err(dn->handle, "Can't tag data node\n");