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, 29 insertions, 0 deletions

diff --git a/include/kunit/fwnode.h b/include/kunit/fwnode.h
new file mode 100644
index 000000000..e250bb87e
--- /dev/null
+++ b/include/kunit/fwnode.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * KUnit resource management helpers for firmware nodes.
+ *
+ * Copyright (C) Qualcomm Technologies, Inc. and/or its subsidiaries
+ */
+
+#ifndef _KUNIT_FWNODE_H
+#define _KUNIT_FWNODE_H
+
+struct device;
+struct fwnode_handle;
+struct kunit;
+struct property_entry;
+struct software_node;
+
+struct fwnode_handle *
+kunit_fwnode_create_software_node(struct kunit *test,
+				  const struct property_entry *properties,
+				  const struct fwnode_handle *parent);
+struct fwnode_handle *
+kunit_software_node_register(struct kunit *test,
+			     const struct software_node *node);
+int kunit_software_node_register_node_group(struct kunit *test,
+					    const struct software_node *const *nodes);
+int kunit_device_add_software_node(struct kunit *test, struct device *dev,
+				   const struct software_node *node);
+
+#endif /* _KUNIT_FWNODE_H */