ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 123 insertions, 0 deletions

diff --git a/Documentation/sphinx/parser_yaml.py b/Documentation/sphinx/parser_yaml.py
new file mode 100755
index 000000000..634d84a20
--- /dev/null
+++ b/Documentation/sphinx/parser_yaml.py
@@ -0,0 +1,123 @@
+# SPDX-License-Identifier: GPL-2.0
+# Copyright 2025 Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
+
+"""
+Sphinx extension for processing YAML files
+"""
+
+import os
+import re
+import sys
+
+from pprint import pformat
+
+from docutils import statemachine
+from docutils.parsers.rst import Parser as RSTParser
+from docutils.parsers.rst import states
+from docutils.statemachine import ViewList
+
+from sphinx.util import logging
+from sphinx.parsers import Parser
+
+srctree = os.path.abspath(os.environ["srctree"])
+sys.path.insert(0, os.path.join(srctree, "tools/net/ynl/pyynl/lib"))
+
+from doc_generator import YnlDocGenerator        # pylint: disable=C0413
+
+logger = logging.getLogger(__name__)
+
+class YamlParser(Parser):
+    """
+    Kernel parser for YAML files.
+
+    This is a simple sphinx.Parser to handle yaml files inside the
+    Kernel tree that will be part of the built documentation.
+
+    The actual parser function is not contained here: the code was
+    written in a way that parsing yaml for different subsystems
+    can be done from a single dispatcher.
+
+    All it takes to have parse YAML patches is to have an import line:
+
+            from some_parser_code import NewYamlGenerator
+
+    To this module. Then add an instance of the parser with:
+
+            new_parser = NewYamlGenerator()
+
+    and add a logic inside parse() to handle it based on the path,
+    like this:
+
+            if "/foo" in fname:
+                msg = self.new_parser.parse_yaml_file(fname)
+    """
+
+    supported = ('yaml', )
+
+    netlink_parser = YnlDocGenerator()
+
+    re_lineno = re.compile(r"\.\. LINENO ([0-9]+)$")
+
+    tab_width = 8
+
+    def rst_parse(self, inputstring, document, msg):
+        """
+        Receives a ReST content that was previously converted by the
+        YAML parser, adding it to the document tree.
+        """
+
+        self.setup_parse(inputstring, document)
+
+        result = ViewList()
+
+        self.statemachine = states.RSTStateMachine(state_classes=states.state_classes,
+                                                   initial_state='Body',
+                                                   debug=document.reporter.debug_flag)
+
+        try:
+            # Parse message with RSTParser
+            lineoffset = 0;
+
+            lines = statemachine.string2lines(msg, self.tab_width,
+                                              convert_whitespace=True)
+
+            for line in lines:
+                match = self.re_lineno.match(line)
+                if match:
+                    lineoffset = int(match.group(1))
+                    continue
+
+                result.append(line, document.current_source, lineoffset)
+
+            self.statemachine.run(result, document)
+
+        except Exception as e:
+            document.reporter.error("YAML parsing error: %s" % pformat(e))
+
+        self.finish_parse()
+
+    # Overrides docutils.parsers.Parser. See sphinx.parsers.RSTParser
+    def parse(self, inputstring, document):
+        """Check if a YAML is meant to be parsed."""
+
+        fname = document.current_source
+
+        # Handle netlink yaml specs
+        if "/netlink/specs/" in fname:
+            msg = self.netlink_parser.parse_yaml_file(fname)
+            self.rst_parse(inputstring, document, msg)
+
+        # All other yaml files are ignored
+
+def setup(app):
+    """Setup function for the Sphinx extension."""
+
+    # Add YAML parser
+    app.add_source_parser(YamlParser)
+    app.add_source_suffix('.yaml', 'yaml')
+
+    return {
+        'version': '1.0',
+        'parallel_read_safe': True,
+        'parallel_write_safe': True,
+    }