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, 60 insertions, 0 deletions

diff --git a/tools/docs/parse-headers.py b/tools/docs/parse-headers.py
new file mode 100755
index 000000000..436acea4c
--- /dev/null
+++ b/tools/docs/parse-headers.py
@@ -0,0 +1,60 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2016, 2025 by Mauro Carvalho Chehab <mchehab@kernel.org>.
+# pylint: disable=C0103
+
+"""
+Convert a C header or source file ``FILE_IN``, into a ReStructured Text
+included via ..parsed-literal block with cross-references for the
+documentation files that describe the API. It accepts an optional
+``FILE_RULES`` file to describes what elements will be either ignored or
+be pointed to a non-default reference type/name.
+
+The output is written at ``FILE_OUT``.
+
+It is capable of identifying defines, functions, structs, typedefs,
+enums and enum symbols and create cross-references for all of them.
+It is also capable of distinguish #define used for specifying a Linux
+ioctl.
+
+The optional ``FILE_RULES`` contains a set of rules like:
+
+    ignore ioctl VIDIOC_ENUM_FMT
+    replace ioctl VIDIOC_DQBUF vidioc_qbuf
+    replace define V4L2_EVENT_MD_FL_HAVE_FRAME_SEQ :c:type:`v4l2_event_motion_det`
+"""
+
+import argparse, sys
+import os.path
+
+src_dir = os.path.dirname(os.path.realpath(__file__))
+sys.path.insert(0, os.path.join(src_dir, '../lib/python'))
+from kdoc.parse_data_structs import ParseDataStructs
+from kdoc.enrich_formatter import EnrichFormatter
+
+def main():
+    """Main function"""
+    parser = argparse.ArgumentParser(description=__doc__,
+                                     formatter_class=EnrichFormatter)
+
+    parser.add_argument("-d", "--debug", action="count", default=0,
+                        help="Increase debug level. Can be used multiple times")
+    parser.add_argument("-t", "--toc", action="store_true",
+                        help="instead of a literal block, outputs a TOC table at the RST file")
+
+    parser.add_argument("file_in", help="Input C file")
+    parser.add_argument("file_out", help="Output RST file")
+    parser.add_argument("file_rules", nargs="?",
+                        help="Exceptions file (optional)")
+
+    args = parser.parse_args()
+
+    parser = ParseDataStructs(debug=args.debug)
+    parser.parse_file(args.file_in, args.file_rules)
+
+    parser.debug_print()
+    parser.write_output(args.file_in, args.file_out, args.toc)
+
+
+if __name__ == "__main__":
+    main()