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, 137 insertions, 0 deletions

diff --git a/Documentation/sphinx/kernel_feat.py b/Documentation/sphinx/kernel_feat.py
new file mode 100644
index 000000000..bdc0fef5c
--- /dev/null
+++ b/Documentation/sphinx/kernel_feat.py
@@ -0,0 +1,137 @@
+# coding=utf-8
+# SPDX-License-Identifier: GPL-2.0
+#
+"""
+    kernel-feat
+    ~~~~~~~~~~~
+
+    Implementation of the ``kernel-feat`` reST-directive.
+
+    :copyright:  Copyright (C) 2016  Markus Heiser
+    :copyright:  Copyright (C) 2016-2019  Mauro Carvalho Chehab
+    :maintained-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
+    :license:    GPL Version 2, June 1991 see Linux/COPYING for details.
+
+    The ``kernel-feat`` (:py:class:`KernelFeat`) directive calls the
+    tools/docs/get_feat.pl script to parse the Kernel ABI files.
+
+    Overview of directive's argument and options.
+
+    .. code-block:: rst
+
+        .. kernel-feat:: <ABI directory location>
+            :debug:
+
+    The argument ``<ABI directory location>`` is required. It contains the
+    location of the ABI files to be parsed.
+
+    ``debug``
+      Inserts a code-block with the *raw* reST. Sometimes it is helpful to see
+      what reST is generated.
+
+"""
+
+import codecs
+import os
+import re
+import sys
+
+from docutils import nodes, statemachine
+from docutils.statemachine import ViewList
+from docutils.parsers.rst import directives, Directive
+from sphinx.util.docutils import switch_source_input
+
+srctree = os.path.abspath(os.environ["srctree"])
+sys.path.insert(0, os.path.join(srctree, "tools/lib/python"))
+
+from feat.parse_features import ParseFeature                # pylint: disable=C0413
+
+def ErrorString(exc):  # Shamelessly stolen from docutils
+    return f'{exc.__class__.__name}: {exc}'
+
+__version__  = '1.0'
+
+def setup(app):
+
+    app.add_directive("kernel-feat", KernelFeat)
+    return dict(
+        version = __version__
+        , parallel_read_safe = True
+        , parallel_write_safe = True
+    )
+
+class KernelFeat(Directive):
+
+    """KernelFeat (``kernel-feat``) directive"""
+
+    required_arguments = 1
+    optional_arguments = 2
+    has_content = False
+    final_argument_whitespace = True
+
+    option_spec = {
+        "debug"     : directives.flag
+    }
+
+    def warn(self, message, **replace):
+        replace["fname"]   = self.state.document.current_source
+        replace["line_no"] = replace.get("line_no", self.lineno)
+        message = ("%(fname)s:%(line_no)s: [kernel-feat WARN] : " + message) % replace
+        self.state.document.settings.env.app.warn(message, prefix="")
+
+    def run(self):
+        doc = self.state.document
+        if not doc.settings.file_insertion_enabled:
+            raise self.warning("docutils: file insertion disabled")
+
+        env = doc.settings.env
+
+        srctree = os.path.abspath(os.environ["srctree"])
+
+        feature_dir = os.path.join(srctree, 'Documentation', self.arguments[0])
+
+        feat = ParseFeature(feature_dir, False, True)
+        feat.parse()
+
+        if len(self.arguments) > 1:
+            arch = self.arguments[1]
+            lines = feat.output_arch_table(arch)
+        else:
+            lines = feat.output_matrix()
+
+        line_regex = re.compile(r"^\.\. FILE (\S+)$")
+
+        out_lines = ""
+
+        for line in lines.split("\n"):
+            match = line_regex.search(line)
+            if match:
+                fname = match.group(1)
+
+                # Add the file to Sphinx build dependencies
+                env.note_dependency(os.path.abspath(fname))
+            else:
+                out_lines += line + "\n"
+
+        nodeList = self.nestedParse(out_lines, self.arguments[0])
+        return nodeList
+
+    def nestedParse(self, lines, fname):
+        content = ViewList()
+        node    = nodes.section()
+
+        if "debug" in self.options:
+            code_block = "\n\n.. code-block:: rst\n    :linenos:\n"
+            for l in lines.split("\n"):
+                code_block += "\n    " + l
+            lines = code_block + "\n\n"
+
+        for c, l in enumerate(lines.split("\n")):
+            content.append(l, fname, c)
+
+        buf  = self.state.memo.title_styles, self.state.memo.section_level, self.state.memo.reporter
+
+        with switch_source_input(self.state, content):
+            self.state.nested_parse(content, 0, node, match_titles=1)
+
+        return node.children