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, 111 insertions, 0 deletions

diff --git a/net/ieee802154/sysfs.c b/net/ieee802154/sysfs.c
new file mode 100644
index 000000000..6708160eb
--- /dev/null
+++ b/net/ieee802154/sysfs.c
@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Authors:
+ * Alexander Aring <aar@pengutronix.de>
+ *
+ * Based on: net/wireless/sysfs.c
+ */
+
+#include <linux/device.h>
+#include <linux/rtnetlink.h>
+
+#include <net/cfg802154.h>
+
+#include "core.h"
+#include "sysfs.h"
+#include "rdev-ops.h"
+
+static inline struct cfg802154_registered_device *
+dev_to_rdev(struct device *dev)
+{
+	return container_of(dev, struct cfg802154_registered_device,
+			    wpan_phy.dev);
+}
+
+#define SHOW_FMT(name, fmt, member)					\
+static ssize_t name ## _show(struct device *dev,			\
+			     struct device_attribute *attr,		\
+			     char *buf)					\
+{									\
+	return sprintf(buf, fmt "\n", dev_to_rdev(dev)->member);	\
+}									\
+static DEVICE_ATTR_RO(name)
+
+SHOW_FMT(index, "%d", wpan_phy_idx);
+
+static ssize_t name_show(struct device *dev,
+			 struct device_attribute *attr,
+			 char *buf)
+{
+	struct wpan_phy *wpan_phy = &dev_to_rdev(dev)->wpan_phy;
+
+	return sprintf(buf, "%s\n", dev_name(&wpan_phy->dev));
+}
+static DEVICE_ATTR_RO(name);
+
+static void wpan_phy_release(struct device *dev)
+{
+	struct cfg802154_registered_device *rdev = dev_to_rdev(dev);
+
+	cfg802154_dev_free(rdev);
+}
+
+static struct attribute *pmib_attrs[] = {
+	&dev_attr_index.attr,
+	&dev_attr_name.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(pmib);
+
+#ifdef CONFIG_PM_SLEEP
+static int wpan_phy_suspend(struct device *dev)
+{
+	struct cfg802154_registered_device *rdev = dev_to_rdev(dev);
+	int ret = 0;
+
+	if (rdev->ops->suspend) {
+		rtnl_lock();
+		ret = rdev_suspend(rdev);
+		rtnl_unlock();
+	}
+
+	return ret;
+}
+
+static int wpan_phy_resume(struct device *dev)
+{
+	struct cfg802154_registered_device *rdev = dev_to_rdev(dev);
+	int ret = 0;
+
+	if (rdev->ops->resume) {
+		rtnl_lock();
+		ret = rdev_resume(rdev);
+		rtnl_unlock();
+	}
+
+	return ret;
+}
+
+static SIMPLE_DEV_PM_OPS(wpan_phy_pm_ops, wpan_phy_suspend, wpan_phy_resume);
+#define WPAN_PHY_PM_OPS (&wpan_phy_pm_ops)
+#else
+#define WPAN_PHY_PM_OPS NULL
+#endif
+
+const struct class wpan_phy_class = {
+	.name = "ieee802154",
+	.dev_release = wpan_phy_release,
+	.dev_groups = pmib_groups,
+	.pm = WPAN_PHY_PM_OPS,
+};
+
+int wpan_phy_sysfs_init(void)
+{
+	return class_register(&wpan_phy_class);
+}
+
+void wpan_phy_sysfs_exit(void)
+{
+	class_unregister(&wpan_phy_class);
+}