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, 44 insertions, 0 deletions

diff --git a/scripts/install.sh b/scripts/install.sh
new file mode 100755
index 000000000..05d62ac51
--- /dev/null
+++ b/scripts/install.sh
@@ -0,0 +1,44 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Copyright (C) 1995 by Linus Torvalds
+#
+# Adapted from code in arch/i386/boot/Makefile by H. Peter Anvin
+# Common code factored out by Masahiro Yamada
+
+set -e
+
+# Make sure the files actually exist
+for file in "${KBUILD_IMAGE}" System.map
+do
+	if [ ! -f "${file}" ]; then
+		echo >&2
+		echo >&2 " *** Missing file: ${file}"
+		echo >&2 ' *** You need to run "make" before "make install".'
+		echo >&2
+		exit 1
+	fi
+done
+
+if [ -n "${INSTALL_PATH}" ] && ! [ -e "${INSTALL_PATH}" ]; then
+	mkdir -p "${INSTALL_PATH}"
+fi
+
+# User/arch may have a custom install script
+for file in "${HOME}/bin/${INSTALLKERNEL}"		\
+	    "/sbin/${INSTALLKERNEL}"			\
+	    "${srctree}/arch/${SRCARCH}/install.sh"	\
+	    "${srctree}/arch/${SRCARCH}/boot/install.sh"
+do
+	if [ ! -x "${file}" ]; then
+		continue
+	fi
+
+	# installkernel(8) says the parameters are like follows:
+	#
+	#   installkernel version zImage System.map [directory]
+	exec "${file}" "${KERNELRELEASE}" "${KBUILD_IMAGE}" System.map "${INSTALL_PATH}"
+done
+
+echo "No install script found" >&2
+exit 1