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, 194 insertions, 0 deletions

diff --git a/drivers/input/joystick/maplecontrol.c b/drivers/input/joystick/maplecontrol.c
new file mode 100644
index 000000000..6293b6e81
--- /dev/null
+++ b/drivers/input/joystick/maplecontrol.c
@@ -0,0 +1,194 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *	SEGA Dreamcast controller driver
+ *	Based on drivers/usb/iforce.c
+ *
+ *	Copyright Yaegashi Takeshi, 2001
+ *	Adrian McMenamin, 2008 - 2009
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/timer.h>
+#include <linux/maple.h>
+
+MODULE_AUTHOR("Adrian McMenamin <adrian@mcmen.demon.co.uk>");
+MODULE_DESCRIPTION("SEGA Dreamcast controller driver");
+MODULE_LICENSE("GPL");
+
+struct dc_pad {
+	struct input_dev *dev;
+	struct maple_device *mdev;
+};
+
+static void dc_pad_callback(struct mapleq *mq)
+{
+	unsigned short buttons;
+	struct maple_device *mapledev = mq->dev;
+	struct dc_pad *pad = maple_get_drvdata(mapledev);
+	struct input_dev *dev = pad->dev;
+	unsigned char *res = mq->recvbuf->buf;
+
+	buttons = ~le16_to_cpup((__le16 *)(res + 8));
+
+	input_report_abs(dev, ABS_HAT0Y,
+		(buttons & 0x0010 ? -1 : 0) + (buttons & 0x0020 ? 1 : 0));
+	input_report_abs(dev, ABS_HAT0X,
+		(buttons & 0x0040 ? -1 : 0) + (buttons & 0x0080 ? 1 : 0));
+	input_report_abs(dev, ABS_HAT1Y,
+		(buttons & 0x1000 ? -1 : 0) + (buttons & 0x2000 ? 1 : 0));
+	input_report_abs(dev, ABS_HAT1X,
+		(buttons & 0x4000 ? -1 : 0) + (buttons & 0x8000 ? 1 : 0));
+
+	input_report_key(dev, BTN_C,      buttons & 0x0001);
+	input_report_key(dev, BTN_B,      buttons & 0x0002);
+	input_report_key(dev, BTN_A,      buttons & 0x0004);
+	input_report_key(dev, BTN_START,  buttons & 0x0008);
+	input_report_key(dev, BTN_Z,      buttons & 0x0100);
+	input_report_key(dev, BTN_Y,      buttons & 0x0200);
+	input_report_key(dev, BTN_X,      buttons & 0x0400);
+	input_report_key(dev, BTN_SELECT, buttons & 0x0800);
+
+	input_report_abs(dev, ABS_GAS,    res[10]);
+	input_report_abs(dev, ABS_BRAKE,  res[11]);
+	input_report_abs(dev, ABS_X,      res[12]);
+	input_report_abs(dev, ABS_Y,      res[13]);
+	input_report_abs(dev, ABS_RX,     res[14]);
+	input_report_abs(dev, ABS_RY,     res[15]);
+}
+
+static int dc_pad_open(struct input_dev *dev)
+{
+	struct dc_pad *pad = dev_get_platdata(&dev->dev);
+
+	maple_getcond_callback(pad->mdev, dc_pad_callback, HZ/20,
+		MAPLE_FUNC_CONTROLLER);
+
+	return 0;
+}
+
+static void dc_pad_close(struct input_dev *dev)
+{
+	struct dc_pad *pad = dev_get_platdata(&dev->dev);
+
+	maple_getcond_callback(pad->mdev, dc_pad_callback, 0,
+		MAPLE_FUNC_CONTROLLER);
+}
+
+/* allow the controller to be used */
+static int probe_maple_controller(struct device *dev)
+{
+	static const short btn_bit[32] = {
+		BTN_C, BTN_B, BTN_A, BTN_START, -1, -1, -1, -1,
+		BTN_Z, BTN_Y, BTN_X, BTN_SELECT, -1, -1, -1, -1,
+		-1, -1, -1, -1, -1, -1, -1, -1,
+		-1, -1, -1, -1, -1, -1, -1, -1,
+	};
+
+	static const short abs_bit[32] = {
+		-1, -1, -1, -1, ABS_HAT0Y, ABS_HAT0Y, ABS_HAT0X, ABS_HAT0X,
+		-1, -1, -1, -1, ABS_HAT1Y, ABS_HAT1Y, ABS_HAT1X, ABS_HAT1X,
+		ABS_GAS, ABS_BRAKE, ABS_X, ABS_Y, ABS_RX, ABS_RY, -1, -1,
+		-1, -1, -1, -1, -1, -1, -1, -1,
+	};
+
+	struct maple_device *mdev = to_maple_dev(dev);
+	struct maple_driver *mdrv = to_maple_driver(dev->driver);
+	int i, error;
+	struct dc_pad *pad;
+	struct input_dev *idev;
+	unsigned long data = be32_to_cpu(mdev->devinfo.function_data[0]);
+
+	pad = kzalloc_obj(*pad);
+	idev = input_allocate_device();
+	if (!pad || !idev) {
+		error = -ENOMEM;
+		goto fail;
+	}
+
+	pad->dev = idev;
+	pad->mdev = mdev;
+
+	maple_set_drvdata(mdev, pad);
+
+	idev->open = dc_pad_open;
+	idev->close = dc_pad_close;
+
+	for (i = 0; i < 32; i++) {
+		if (data & (1 << i)) {
+			if (btn_bit[i] >= 0)
+				__set_bit(btn_bit[i], idev->keybit);
+			else if (abs_bit[i] >= 0)
+				__set_bit(abs_bit[i], idev->absbit);
+		}
+	}
+
+	if (idev->keybit[BIT_WORD(BTN_JOYSTICK)])
+		idev->evbit[0] |= BIT_MASK(EV_KEY);
+
+	if (idev->absbit[0])
+		idev->evbit[0] |= BIT_MASK(EV_ABS);
+
+	for (i = ABS_X; i <= ABS_BRAKE; i++)
+		input_set_abs_params(idev, i, 0, 255, 0, 0);
+
+	for (i = ABS_HAT0X; i <= ABS_HAT3Y; i++)
+		input_set_abs_params(idev, i, 1, -1, 0, 0);
+
+	idev->dev.platform_data = pad;
+	idev->dev.parent = &mdev->dev;
+	idev->name = mdev->product_name;
+	idev->id.bustype = BUS_HOST;
+
+	error = input_register_device(idev);
+	if (error)
+		goto fail;
+
+	mdev->driver = mdrv;
+
+	return 0;
+
+fail:
+	input_free_device(idev);
+	kfree(pad);
+	maple_set_drvdata(mdev, NULL);
+	return error;
+}
+
+static int remove_maple_controller(struct device *dev)
+{
+	struct maple_device *mdev = to_maple_dev(dev);
+	struct dc_pad *pad = maple_get_drvdata(mdev);
+
+	mdev->callback = NULL;
+	input_unregister_device(pad->dev);
+	maple_set_drvdata(mdev, NULL);
+	kfree(pad);
+
+	return 0;
+}
+
+static struct maple_driver dc_pad_driver = {
+	.function =	MAPLE_FUNC_CONTROLLER,
+	.drv = {
+		.name	= "Dreamcast_controller",
+		.probe	= probe_maple_controller,
+		.remove	= remove_maple_controller,
+	},
+};
+
+static int __init dc_pad_init(void)
+{
+	return maple_driver_register(&dc_pad_driver);
+}
+
+static void __exit dc_pad_exit(void)
+{
+	maple_driver_unregister(&dc_pad_driver);
+}
+
+module_init(dc_pad_init);
+module_exit(dc_pad_exit);