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, 74 insertions, 0 deletions

diff --git a/drivers/comedi/proc.c b/drivers/comedi/proc.c
new file mode 100644
index 000000000..2e4496633
--- /dev/null
+++ b/drivers/comedi/proc.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * /proc interface for comedi
+ *
+ * COMEDI - Linux Control and Measurement Device Interface
+ * Copyright (C) 1998 David A. Schleef <ds@schleef.org>
+ */
+
+/*
+ * This is some serious bloatware.
+ *
+ * Taken from Dave A.'s PCL-711 driver, 'cuz I thought it
+ * was cool.
+ */
+
+#include <linux/comedi/comedidev.h>
+#include "comedi_internal.h"
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+
+static int comedi_read(struct seq_file *m, void *v)
+{
+	int i;
+	int devices_q = 0;
+	struct comedi_driver *driv;
+
+	seq_printf(m, "comedi version " COMEDI_RELEASE "\nformat string: %s\n",
+		   "\"%2d: %-20s %-20s %4d\", i, driver_name, board_name, n_subdevices");
+
+	for (i = 0; i < COMEDI_NUM_BOARD_MINORS; i++) {
+		struct comedi_device *dev = comedi_dev_get_from_minor(i);
+
+		if (!dev)
+			continue;
+
+		down_read(&dev->attach_lock);
+		if (dev->attached) {
+			devices_q = 1;
+			seq_printf(m, "%2d: %-20s %-20s %4d\n",
+				   i, dev->driver->driver_name,
+				   dev->board_name, dev->n_subdevices);
+		}
+		up_read(&dev->attach_lock);
+		comedi_dev_put(dev);
+	}
+	if (!devices_q)
+		seq_puts(m, "no devices\n");
+
+	mutex_lock(&comedi_drivers_list_lock);
+	for (driv = comedi_drivers; driv; driv = driv->next) {
+		seq_printf(m, "%s:\n", driv->driver_name);
+		for (i = 0; i < driv->num_names; i++)
+			seq_printf(m, " %s\n",
+				   *(char **)((char *)driv->board_name +
+					      i * driv->offset));
+
+		if (!driv->num_names)
+			seq_printf(m, " %s\n", driv->driver_name);
+	}
+	mutex_unlock(&comedi_drivers_list_lock);
+
+	return 0;
+}
+
+void __init comedi_proc_init(void)
+{
+	if (!proc_create_single("comedi", 0444, NULL, comedi_read))
+		pr_warn("comedi: unable to create proc entry\n");
+}
+
+void comedi_proc_cleanup(void)
+{
+	remove_proc_entry("comedi", NULL);
+}