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, 89 insertions, 0 deletions

diff --git a/drivers/ps3/vuart.h b/drivers/ps3/vuart.h
new file mode 100644
index 000000000..64d34efef
--- /dev/null
+++ b/drivers/ps3/vuart.h
@@ -0,0 +1,89 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ *  PS3 virtual uart
+ *
+ *  Copyright (C) 2006 Sony Computer Entertainment Inc.
+ *  Copyright 2006 Sony Corp.
+ */
+
+#if !defined(_PS3_VUART_H)
+#define _PS3_VUART_H
+
+#include <asm/ps3.h>
+
+struct ps3_vuart_stats {
+	unsigned long bytes_written;
+	unsigned long bytes_read;
+	unsigned long tx_interrupts;
+	unsigned long rx_interrupts;
+	unsigned long disconnect_interrupts;
+};
+
+struct ps3_vuart_work {
+	struct work_struct work;
+	unsigned long trigger;
+	struct ps3_system_bus_device *dev; /* to convert work to device */
+};
+
+/**
+ * struct ps3_vuart_port_driver - a driver for a device on a vuart port
+ */
+
+struct ps3_vuart_port_driver {
+	struct ps3_system_bus_driver core;
+	int (*probe)(struct ps3_system_bus_device *);
+	int (*remove)(struct ps3_system_bus_device *);
+	void (*shutdown)(struct ps3_system_bus_device *);
+	void (*work)(struct ps3_system_bus_device *);
+	/* int (*tx_event)(struct ps3_system_bus_device *dev); */
+	/* int (*rx_event)(struct ps3_system_bus_device *dev); */
+	/* int (*disconnect_event)(struct ps3_system_bus_device *dev); */
+	/* int (*suspend)(struct ps3_system_bus_device *, pm_message_t); */
+	/* int (*resume)(struct ps3_system_bus_device *); */
+};
+
+int ps3_vuart_port_driver_register(struct ps3_vuart_port_driver *drv);
+void ps3_vuart_port_driver_unregister(struct ps3_vuart_port_driver *drv);
+
+static inline struct ps3_vuart_port_driver *
+	ps3_system_bus_dev_to_vuart_drv(struct ps3_system_bus_device *_dev)
+{
+	struct ps3_system_bus_driver *sbd =
+		ps3_system_bus_dev_to_system_bus_drv(_dev);
+	BUG_ON(!sbd);
+	return container_of(sbd, struct ps3_vuart_port_driver, core);
+}
+static inline struct ps3_system_bus_device *ps3_vuart_work_to_system_bus_dev(
+	struct work_struct *_work)
+{
+	struct ps3_vuart_work *vw = container_of(_work, struct ps3_vuart_work,
+		work);
+	return vw->dev;
+}
+
+int ps3_vuart_write(struct ps3_system_bus_device *dev, const void *buf,
+	unsigned int bytes);
+int ps3_vuart_read(struct ps3_system_bus_device *dev, void *buf,
+	unsigned int bytes);
+int ps3_vuart_read_async(struct ps3_system_bus_device *dev, unsigned int bytes);
+void ps3_vuart_cancel_async(struct ps3_system_bus_device *dev);
+void ps3_vuart_clear_rx_bytes(struct ps3_system_bus_device *dev,
+	unsigned int bytes);
+
+struct vuart_triggers {
+	unsigned long rx;
+	unsigned long tx;
+};
+
+int ps3_vuart_get_triggers(struct ps3_system_bus_device *dev,
+	struct vuart_triggers *trig);
+int ps3_vuart_set_triggers(struct ps3_system_bus_device *dev, unsigned int tx,
+	unsigned int rx);
+int ps3_vuart_enable_interrupt_tx(struct ps3_system_bus_device *dev);
+int ps3_vuart_disable_interrupt_tx(struct ps3_system_bus_device *dev);
+int ps3_vuart_enable_interrupt_rx(struct ps3_system_bus_device *dev);
+int ps3_vuart_disable_interrupt_rx(struct ps3_system_bus_device *dev);
+int ps3_vuart_enable_interrupt_disconnect(struct ps3_system_bus_device *dev);
+int ps3_vuart_disable_interrupt_disconnect(struct ps3_system_bus_device *dev);
+
+#endif