x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

The local "root" pointer is a temporary variable used during the device
search. Therefore, refcount related to the search iterators should be cleaned
up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the
temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures
the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The
pci_get_class() iterator always decrements the refcount of its "from"
argument, so the first loop can only fall through with "root" already NULL.

Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

1 files changed, 144 insertions, 0 deletions

diff --git a/drivers/base/physical_location.c b/drivers/base/physical_location.c
new file mode 100644
index 000000000..2e723fff6
--- /dev/null
+++ b/drivers/base/physical_location.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Device physical location support
+ *
+ * Author: Won Chung <wonchung@google.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/sysfs.h>
+#include <linux/string_choices.h>
+
+#include "physical_location.h"
+
+bool dev_add_physical_location(struct device *dev)
+{
+	struct acpi_pld_info *pld;
+
+	if (!has_acpi_companion(dev))
+		return false;
+
+	if (!acpi_get_physical_device_location(ACPI_HANDLE(dev), &pld))
+		return false;
+
+	dev->physical_location = kzalloc_obj(*dev->physical_location);
+	if (!dev->physical_location) {
+		ACPI_FREE(pld);
+		return false;
+	}
+
+	dev->physical_location->panel = pld->panel;
+	dev->physical_location->vertical_position = pld->vertical_position;
+	dev->physical_location->horizontal_position = pld->horizontal_position;
+	dev->physical_location->dock = pld->dock;
+	dev->physical_location->lid = pld->lid;
+
+	ACPI_FREE(pld);
+	return true;
+}
+
+static ssize_t panel_show(struct device *dev, struct device_attribute *attr,
+	char *buf)
+{
+	const char *panel;
+
+	switch (dev->physical_location->panel) {
+	case DEVICE_PANEL_TOP:
+		panel = "top";
+		break;
+	case DEVICE_PANEL_BOTTOM:
+		panel = "bottom";
+		break;
+	case DEVICE_PANEL_LEFT:
+		panel = "left";
+		break;
+	case DEVICE_PANEL_RIGHT:
+		panel = "right";
+		break;
+	case DEVICE_PANEL_FRONT:
+		panel = "front";
+		break;
+	case DEVICE_PANEL_BACK:
+		panel = "back";
+		break;
+	default:
+		panel = "unknown";
+	}
+	return sysfs_emit(buf, "%s\n", panel);
+}
+static DEVICE_ATTR_RO(panel);
+
+static ssize_t vertical_position_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	const char *vertical_position;
+
+	switch (dev->physical_location->vertical_position) {
+	case DEVICE_VERT_POS_UPPER:
+		vertical_position = "upper";
+		break;
+	case DEVICE_VERT_POS_CENTER:
+		vertical_position = "center";
+		break;
+	case DEVICE_VERT_POS_LOWER:
+		vertical_position = "lower";
+		break;
+	default:
+		vertical_position = "unknown";
+	}
+	return sysfs_emit(buf, "%s\n", vertical_position);
+}
+static DEVICE_ATTR_RO(vertical_position);
+
+static ssize_t horizontal_position_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	const char *horizontal_position;
+
+	switch (dev->physical_location->horizontal_position) {
+	case DEVICE_HORI_POS_LEFT:
+		horizontal_position = "left";
+		break;
+	case DEVICE_HORI_POS_CENTER:
+		horizontal_position = "center";
+		break;
+	case DEVICE_HORI_POS_RIGHT:
+		horizontal_position = "right";
+		break;
+	default:
+		horizontal_position = "unknown";
+	}
+	return sysfs_emit(buf, "%s\n", horizontal_position);
+}
+static DEVICE_ATTR_RO(horizontal_position);
+
+static ssize_t dock_show(struct device *dev, struct device_attribute *attr,
+	char *buf)
+{
+	return sysfs_emit(buf, "%s\n",
+		str_yes_no(dev->physical_location->dock));
+}
+static DEVICE_ATTR_RO(dock);
+
+static ssize_t lid_show(struct device *dev, struct device_attribute *attr,
+	char *buf)
+{
+	return sysfs_emit(buf, "%s\n",
+		str_yes_no(dev->physical_location->lid));
+}
+static DEVICE_ATTR_RO(lid);
+
+static struct attribute *dev_attr_physical_location[] = {
+	&dev_attr_panel.attr,
+	&dev_attr_vertical_position.attr,
+	&dev_attr_horizontal_position.attr,
+	&dev_attr_dock.attr,
+	&dev_attr_lid.attr,
+	NULL,
+};
+
+const struct attribute_group dev_attr_physical_location_group = {
+	.name = "physical_location",
+	.attrs = dev_attr_physical_location,
+};
+