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, 49 insertions, 0 deletions

diff --git a/net/atm/resources.h b/net/atm/resources.h
new file mode 100644
index 000000000..4a0839e92
--- /dev/null
+++ b/net/atm/resources.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* net/atm/resources.h - ATM-related resources */
+
+/* Written 1995-1998 by Werner Almesberger, EPFL LRC/ICA */
+
+
+#ifndef NET_ATM_RESOURCES_H
+#define NET_ATM_RESOURCES_H
+
+#include <linux/atmdev.h>
+#include <linux/mutex.h>
+
+
+extern struct list_head atm_devs;
+extern struct mutex atm_dev_mutex;
+
+int atm_getnames(void __user *buf, int __user *iobuf_len);
+int atm_dev_ioctl(unsigned int cmd, void __user *buf, int __user *sioc_len,
+		  int number, int compat);
+
+#ifdef CONFIG_PROC_FS
+
+#include <linux/proc_fs.h>
+
+void *atm_dev_seq_start(struct seq_file *seq, loff_t *pos);
+void atm_dev_seq_stop(struct seq_file *seq, void *v);
+void *atm_dev_seq_next(struct seq_file *seq, void *v, loff_t *pos);
+
+
+int atm_proc_dev_register(struct atm_dev *dev);
+void atm_proc_dev_deregister(struct atm_dev *dev);
+
+#else
+
+static inline int atm_proc_dev_register(struct atm_dev *dev)
+{
+	return 0;
+}
+
+static inline void atm_proc_dev_deregister(struct atm_dev *dev)
+{
+	/* nothing */
+}
+
+#endif /* CONFIG_PROC_FS */
+
+int atm_register_sysfs(struct atm_dev *adev, struct device *parent);
+void atm_unregister_sysfs(struct atm_dev *adev);
+#endif