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, 158 insertions, 0 deletions

diff --git a/net/atm/atm_sysfs.c b/net/atm/atm_sysfs.c
new file mode 100644
index 000000000..0676a9c33
--- /dev/null
+++ b/net/atm/atm_sysfs.c
@@ -0,0 +1,158 @@
+// SPDX-License-Identifier: GPL-2.0
+/* ATM driver model support. */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/kobject.h>
+#include <linux/atmdev.h>
+#include "common.h"
+#include "resources.h"
+
+#define to_atm_dev(cldev) container_of(cldev, struct atm_dev, class_dev)
+
+static ssize_t type_show(struct device *cdev,
+			 struct device_attribute *attr, char *buf)
+{
+	struct atm_dev *adev = to_atm_dev(cdev);
+
+	return scnprintf(buf, PAGE_SIZE, "%s\n", adev->type);
+}
+
+static ssize_t address_show(struct device *cdev,
+			    struct device_attribute *attr, char *buf)
+{
+	struct atm_dev *adev = to_atm_dev(cdev);
+
+	return scnprintf(buf, PAGE_SIZE, "%pM\n", adev->esi);
+}
+
+static ssize_t atmindex_show(struct device *cdev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct atm_dev *adev = to_atm_dev(cdev);
+
+	return scnprintf(buf, PAGE_SIZE, "%d\n", adev->number);
+}
+
+static ssize_t carrier_show(struct device *cdev,
+			    struct device_attribute *attr, char *buf)
+{
+	struct atm_dev *adev = to_atm_dev(cdev);
+
+	return scnprintf(buf, PAGE_SIZE, "%d\n",
+			 adev->signal == ATM_PHY_SIG_LOST ? 0 : 1);
+}
+
+static ssize_t link_rate_show(struct device *cdev,
+			      struct device_attribute *attr, char *buf)
+{
+	struct atm_dev *adev = to_atm_dev(cdev);
+	int link_rate;
+
+	/* show the link rate, not the data rate */
+	switch (adev->link_rate) {
+	case ATM_OC3_PCR:
+		link_rate = 155520000;
+		break;
+	case ATM_OC12_PCR:
+		link_rate = 622080000;
+		break;
+	case ATM_25_PCR:
+		link_rate = 25600000;
+		break;
+	default:
+		link_rate = adev->link_rate * 8 * 53;
+	}
+	return scnprintf(buf, PAGE_SIZE, "%d\n", link_rate);
+}
+
+static DEVICE_ATTR_RO(address);
+static DEVICE_ATTR_RO(atmindex);
+static DEVICE_ATTR_RO(carrier);
+static DEVICE_ATTR_RO(type);
+static DEVICE_ATTR_RO(link_rate);
+
+static struct device_attribute *atm_attrs[] = {
+	&dev_attr_address,
+	&dev_attr_atmindex,
+	&dev_attr_carrier,
+	&dev_attr_type,
+	&dev_attr_link_rate,
+	NULL
+};
+
+
+static int atm_uevent(const struct device *cdev, struct kobj_uevent_env *env)
+{
+	const struct atm_dev *adev;
+
+	if (!cdev)
+		return -ENODEV;
+
+	adev = to_atm_dev(cdev);
+
+	if (add_uevent_var(env, "NAME=%s%d", adev->type, adev->number))
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void atm_release(struct device *cdev)
+{
+	struct atm_dev *adev = to_atm_dev(cdev);
+
+	kfree(adev);
+}
+
+static struct class atm_class = {
+	.name		= "atm",
+	.dev_release	= atm_release,
+	.dev_uevent		= atm_uevent,
+};
+
+int atm_register_sysfs(struct atm_dev *adev, struct device *parent)
+{
+	struct device *cdev = &adev->class_dev;
+	int i, j, err;
+
+	cdev->class = &atm_class;
+	cdev->parent = parent;
+	dev_set_drvdata(cdev, adev);
+
+	dev_set_name(cdev, "%s%d", adev->type, adev->number);
+	err = device_register(cdev);
+	if (err < 0)
+		return err;
+
+	for (i = 0; atm_attrs[i]; i++) {
+		err = device_create_file(cdev, atm_attrs[i]);
+		if (err)
+			goto err_out;
+	}
+
+	return 0;
+
+err_out:
+	for (j = 0; j < i; j++)
+		device_remove_file(cdev, atm_attrs[j]);
+	device_del(cdev);
+	return err;
+}
+
+void atm_unregister_sysfs(struct atm_dev *adev)
+{
+	struct device *cdev = &adev->class_dev;
+
+	device_del(cdev);
+}
+
+int __init atm_sysfs_init(void)
+{
+	return class_register(&atm_class);
+}
+
+void __exit atm_sysfs_exit(void)
+{
+	class_unregister(&atm_class);
+}