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, 72 insertions, 0 deletions

diff --git a/include/net/ncsi.h b/include/net/ncsi.h
new file mode 100644
index 000000000..e88635820
--- /dev/null
+++ b/include/net/ncsi.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __NET_NCSI_H
+#define __NET_NCSI_H
+
+#include <linux/types.h>
+
+/*
+ * The NCSI device states seen from external. More NCSI device states are
+ * only visible internally (in net/ncsi/internal.h). When the NCSI device
+ * is registered, it's in ncsi_dev_state_registered state. The state
+ * ncsi_dev_state_start is used to drive to choose active package and
+ * channel. After that, its state is changed to ncsi_dev_state_functional.
+ *
+ * The state ncsi_dev_state_stop helps to shut down the currently active
+ * package and channel while ncsi_dev_state_config helps to reconfigure
+ * them.
+ */
+enum {
+	ncsi_dev_state_registered	= 0x0000,
+	ncsi_dev_state_functional	= 0x0100,
+	ncsi_dev_state_probe		= 0x0200,
+	ncsi_dev_state_config		= 0x0300,
+	ncsi_dev_state_suspend		= 0x0400,
+};
+
+struct ncsi_dev {
+	int               state;
+	int		  link_up;
+	struct net_device *dev;
+	void		  (*handler)(struct ncsi_dev *ndev);
+};
+
+#ifdef CONFIG_NET_NCSI
+int ncsi_vlan_rx_add_vid(struct net_device *dev, __be16 proto, u16 vid);
+int ncsi_vlan_rx_kill_vid(struct net_device *dev, __be16 proto, u16 vid);
+struct ncsi_dev *ncsi_register_dev(struct net_device *dev,
+				   void (*notifier)(struct ncsi_dev *nd));
+int ncsi_start_dev(struct ncsi_dev *nd);
+void ncsi_stop_dev(struct ncsi_dev *nd);
+void ncsi_unregister_dev(struct ncsi_dev *nd);
+#else /* !CONFIG_NET_NCSI */
+static inline int ncsi_vlan_rx_add_vid(struct net_device *dev, __be16 proto, u16 vid)
+{
+	return -EINVAL;
+}
+
+static inline int ncsi_vlan_rx_kill_vid(struct net_device *dev, __be16 proto, u16 vid)
+{
+	return -EINVAL;
+}
+
+static inline struct ncsi_dev *ncsi_register_dev(struct net_device *dev,
+					void (*notifier)(struct ncsi_dev *nd))
+{
+	return NULL;
+}
+
+static inline int ncsi_start_dev(struct ncsi_dev *nd)
+{
+	return -ENOTTY;
+}
+
+static inline void ncsi_stop_dev(struct ncsi_dev *nd)
+{
+}
+
+static inline void ncsi_unregister_dev(struct ncsi_dev *nd)
+{
+}
+#endif /* CONFIG_NET_NCSI */
+
+#endif /* __NET_NCSI_H */