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, 62 insertions, 0 deletions

diff --git a/fs/udf/lowlevel.c b/fs/udf/lowlevel.c
new file mode 100644
index 000000000..9d847a7a0
--- /dev/null
+++ b/fs/udf/lowlevel.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * lowlevel.c
+ *
+ * PURPOSE
+ *  Low Level Device Routines for the UDF filesystem
+ *
+ * COPYRIGHT
+ *  (C) 1999-2001 Ben Fennema
+ *
+ * HISTORY
+ *
+ *  03/26/99 blf  Created.
+ */
+
+#include "udfdecl.h"
+
+#include <linux/blkdev.h>
+#include <linux/cdrom.h>
+#include <linux/uaccess.h>
+
+#include "udf_sb.h"
+
+unsigned int udf_get_last_session(struct super_block *sb)
+{
+	struct cdrom_device_info *cdi = disk_to_cdi(sb->s_bdev->bd_disk);
+	struct cdrom_multisession ms_info;
+
+	if (!cdi) {
+		udf_debug("CDROMMULTISESSION not supported.\n");
+		return 0;
+	}
+
+	ms_info.addr_format = CDROM_LBA;
+	if (cdrom_multisession(cdi, &ms_info) == 0) {
+		udf_debug("XA disk: %s, vol_desc_start=%d\n",
+			  ms_info.xa_flag ? "yes" : "no", ms_info.addr.lba);
+		if (ms_info.xa_flag) /* necessary for a valid ms_info.addr */
+			return ms_info.addr.lba;
+	}
+	return 0;
+}
+
+udf_pblk_t udf_get_last_block(struct super_block *sb)
+{
+	struct cdrom_device_info *cdi = disk_to_cdi(sb->s_bdev->bd_disk);
+	unsigned long lblock = 0;
+
+	/*
+	 * The cdrom layer call failed or returned obviously bogus value?
+	 * Try using the device size...
+	 */
+	if (!cdi || cdrom_get_last_written(cdi, &lblock) || lblock == 0) {
+		if (sb_bdev_nr_blocks(sb) > ~(udf_pblk_t)0)
+			return 0;
+		lblock = sb_bdev_nr_blocks(sb);
+	}
+
+	if (lblock)
+		return lblock - 1;
+	return 0;
+}