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, 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