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, 82 insertions, 0 deletions

diff --git a/drivers/dio/dio-sysfs.c b/drivers/dio/dio-sysfs.c
new file mode 100644
index 000000000..ee1a3b59b
--- /dev/null
+++ b/drivers/dio/dio-sysfs.c
@@ -0,0 +1,82 @@
+/*
+ *  File Attributes for DIO Devices
+ *
+ *  Copyright (C) 2004 Jochen Friedrich
+ *
+ *  Loosely based on drivers/pci/pci-sysfs.c and drivers/zorro/zorro-sysfs.c
+ *
+ *  This file is subject to the terms and conditions of the GNU General Public
+ *  License.  See the file COPYING in the main directory of this archive
+ *  for more details.
+ */
+
+
+#include <linux/kernel.h>
+#include <linux/dio.h>
+#include <linux/stat.h>
+
+/* show configuration fields */
+
+static ssize_t dio_show_id(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct dio_dev *d;
+
+	d = to_dio_dev(dev);
+	return sprintf(buf, "0x%02x\n", (d->id & 0xff));
+}
+static DEVICE_ATTR(id, S_IRUGO, dio_show_id, NULL);
+
+static ssize_t dio_show_ipl(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct dio_dev *d;
+
+	d = to_dio_dev(dev);
+	return sprintf(buf, "0x%02x\n", d->ipl);
+}
+static DEVICE_ATTR(ipl, S_IRUGO, dio_show_ipl, NULL);
+
+static ssize_t dio_show_secid(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct dio_dev *d;
+
+	d = to_dio_dev(dev);
+	return sprintf(buf, "0x%02x\n", ((d->id >> 8)& 0xff));
+}
+static DEVICE_ATTR(secid, S_IRUGO, dio_show_secid, NULL);
+
+static ssize_t dio_show_name(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct dio_dev *d;
+
+	d = to_dio_dev(dev);
+	return sprintf(buf, "%s\n", d->name);
+}
+static DEVICE_ATTR(name, S_IRUGO, dio_show_name, NULL);
+
+static ssize_t dio_show_resource(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct dio_dev *d = to_dio_dev(dev);
+
+	return sprintf(buf, "0x%08lx 0x%08lx 0x%08lx\n",
+		       (unsigned long)dio_resource_start(d),
+		       (unsigned long)dio_resource_end(d),
+		       dio_resource_flags(d));
+}
+static DEVICE_ATTR(resource, S_IRUGO, dio_show_resource, NULL);
+
+int dio_create_sysfs_dev_files(struct dio_dev *d)
+{
+	struct device *dev = &d->dev;
+	int error;
+
+	/* current configuration's attributes */
+	if ((error = device_create_file(dev, &dev_attr_id)) ||
+	    (error = device_create_file(dev, &dev_attr_ipl)) ||
+	    (error = device_create_file(dev, &dev_attr_secid)) ||
+	    (error = device_create_file(dev, &dev_attr_name)) ||
+	    (error = device_create_file(dev, &dev_attr_resource)))
+		return error;
+
+	return 0;
+}
+