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, 138 insertions, 0 deletions

diff --git a/net/bluetooth/hci_sysfs.c b/net/bluetooth/hci_sysfs.c
new file mode 100644
index 000000000..8957ce7c2
--- /dev/null
+++ b/net/bluetooth/hci_sysfs.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Bluetooth HCI driver model support. */
+
+#include <linux/module.h>
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+static const struct class bt_class = {
+	.name = "bluetooth",
+};
+
+static void bt_link_release(struct device *dev)
+{
+	struct hci_conn *conn = to_hci_conn(dev);
+	kfree(conn);
+}
+
+static const struct device_type bt_link = {
+	.name    = "link",
+	.release = bt_link_release,
+};
+
+void hci_conn_init_sysfs(struct hci_conn *conn)
+{
+	struct hci_dev *hdev = conn->hdev;
+
+	bt_dev_dbg(hdev, "conn %p", conn);
+
+	conn->dev.type = &bt_link;
+	conn->dev.class = &bt_class;
+	conn->dev.parent = &hdev->dev;
+
+	device_initialize(&conn->dev);
+}
+
+void hci_conn_add_sysfs(struct hci_conn *conn)
+{
+	struct hci_dev *hdev = conn->hdev;
+
+	bt_dev_dbg(hdev, "conn %p", conn);
+
+	if (device_is_registered(&conn->dev))
+		return;
+
+	dev_set_name(&conn->dev, "%s:%d", hdev->name, conn->handle);
+
+	if (device_add(&conn->dev) < 0)
+		bt_dev_err(hdev, "failed to register connection device");
+}
+
+void hci_conn_del_sysfs(struct hci_conn *conn)
+{
+	struct hci_dev *hdev = conn->hdev;
+
+	bt_dev_dbg(hdev, "conn %p", conn);
+
+	if (!device_is_registered(&conn->dev)) {
+		/* If device_add() has *not* succeeded, use *only* put_device()
+		 * to drop the reference count.
+		 */
+		put_device(&conn->dev);
+		return;
+	}
+
+	/* If there are devices using the connection as parent reset it to NULL
+	 * before unregistering the device.
+	 */
+	while (1) {
+		struct device *dev;
+
+		dev = device_find_any_child(&conn->dev);
+		if (!dev)
+			break;
+		device_move(dev, NULL, DPM_ORDER_DEV_LAST);
+		put_device(dev);
+	}
+
+	device_unregister(&conn->dev);
+}
+
+static void bt_host_release(struct device *dev)
+{
+	struct hci_dev *hdev = to_hci_dev(dev);
+
+	if (hci_dev_test_flag(hdev, HCI_UNREGISTER)) {
+		hci_release_dev(hdev);
+	} else {
+		cleanup_srcu_struct(&hdev->srcu);
+		kfree(hdev);
+	}
+	module_put(THIS_MODULE);
+}
+
+static ssize_t reset_store(struct device *dev, struct device_attribute *attr,
+			   const char *buf, size_t count)
+{
+	struct hci_dev *hdev = to_hci_dev(dev);
+
+	if (hdev->reset)
+		hdev->reset(hdev);
+
+	return count;
+}
+static DEVICE_ATTR_WO(reset);
+
+static struct attribute *bt_host_attrs[] = {
+	&dev_attr_reset.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(bt_host);
+
+static const struct device_type bt_host = {
+	.name    = "host",
+	.release = bt_host_release,
+	.groups = bt_host_groups,
+};
+
+void hci_init_sysfs(struct hci_dev *hdev)
+{
+	struct device *dev = &hdev->dev;
+
+	dev->type = &bt_host;
+	dev->class = &bt_class;
+
+	__module_get(THIS_MODULE);
+	device_initialize(dev);
+}
+
+int __init bt_sysfs_init(void)
+{
+	return class_register(&bt_class);
+}
+
+void bt_sysfs_cleanup(void)
+{
+	class_unregister(&bt_class);
+}