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, 61 insertions, 0 deletions

diff --git a/fs/befs/io.c b/fs/befs/io.c
new file mode 100644
index 000000000..2caf50a4a
--- /dev/null
+++ b/fs/befs/io.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/fs/befs/io.c
+ *
+ * Copyright (C) 2001 Will Dyson <will_dyson@pobox.com
+ *
+ * Based on portions of file.c and inode.c
+ * by Makoto Kato (m_kato@ga2.so-net.ne.jp)
+ *
+ * Many thanks to Dominic Giampaolo, author of Practical File System
+ * Design with the Be File System, for such a helpful book.
+ *
+ */
+
+#include <linux/buffer_head.h>
+
+#include "befs.h"
+#include "io.h"
+
+/*
+ * Converts befs notion of disk addr to a disk offset and uses
+ * linux kernel function sb_bread() to get the buffer containing
+ * the offset.
+ */
+
+struct buffer_head *
+befs_bread_iaddr(struct super_block *sb, befs_inode_addr iaddr)
+{
+	struct buffer_head *bh;
+	befs_blocknr_t block;
+	struct befs_sb_info *befs_sb = BEFS_SB(sb);
+
+	befs_debug(sb, "---> Enter %s "
+		   "[%u, %hu, %hu]", __func__, iaddr.allocation_group,
+		   iaddr.start, iaddr.len);
+
+	if (iaddr.allocation_group > befs_sb->num_ags) {
+		befs_error(sb, "BEFS: Invalid allocation group %u, max is %u",
+			   iaddr.allocation_group, befs_sb->num_ags);
+		goto error;
+	}
+
+	block = iaddr2blockno(sb, &iaddr);
+
+	befs_debug(sb, "%s: offset = %lu", __func__, (unsigned long)block);
+
+	bh = sb_bread(sb, block);
+
+	if (bh == NULL) {
+		befs_error(sb, "Failed to read block %lu",
+			   (unsigned long)block);
+		goto error;
+	}
+
+	befs_debug(sb, "<--- %s", __func__);
+	return bh;
+
+error:
+	befs_debug(sb, "<--- %s ERROR", __func__);
+	return NULL;
+}