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, 150 insertions, 0 deletions

diff --git a/drivers/input/mouse/amimouse.c b/drivers/input/mouse/amimouse.c
new file mode 100644
index 000000000..d203c2a6c
--- /dev/null
+++ b/drivers/input/mouse/amimouse.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Amiga mouse driver for Linux/m68k
+ *
+ *  Copyright (c) 2000-2002 Vojtech Pavlik
+ *
+ *  Based on the work of:
+ *	Michael Rausch		James Banks
+ *	Matther Dillon		David Giller
+ *	Nathan Laredo		Linus Torvalds
+ *	Johan Myreen		Jes Sorensen
+ *	Russell King
+ */
+
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+
+#include <asm/irq.h>
+#include <asm/setup.h>
+#include <linux/uaccess.h>
+#include <asm/amigahw.h>
+#include <asm/amigaints.h>
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION("Amiga mouse driver");
+MODULE_LICENSE("GPL");
+
+static int amimouse_lastx, amimouse_lasty;
+
+static irqreturn_t amimouse_interrupt(int irq, void *data)
+{
+	struct input_dev *dev = data;
+	unsigned short joy0dat, potgor;
+	int nx, ny, dx, dy;
+
+	joy0dat = amiga_custom.joy0dat;
+
+	nx = joy0dat & 0xff;
+	ny = joy0dat >> 8;
+
+	dx = nx - amimouse_lastx;
+	dy = ny - amimouse_lasty;
+
+	if (dx < -127) dx = (256 + nx) - amimouse_lastx;
+	if (dx >  127) dx = (nx - 256) - amimouse_lastx;
+	if (dy < -127) dy = (256 + ny) - amimouse_lasty;
+	if (dy >  127) dy = (ny - 256) - amimouse_lasty;
+
+	amimouse_lastx = nx;
+	amimouse_lasty = ny;
+
+	potgor = amiga_custom.potgor;
+
+	input_report_rel(dev, REL_X, dx);
+	input_report_rel(dev, REL_Y, dy);
+
+	input_report_key(dev, BTN_LEFT,   ciaa.pra & 0x40);
+	input_report_key(dev, BTN_MIDDLE, potgor & 0x0100);
+	input_report_key(dev, BTN_RIGHT,  potgor & 0x0400);
+
+	input_sync(dev);
+
+	return IRQ_HANDLED;
+}
+
+static int amimouse_open(struct input_dev *dev)
+{
+	unsigned short joy0dat;
+	int error;
+
+	joy0dat = amiga_custom.joy0dat;
+
+	amimouse_lastx = joy0dat & 0xff;
+	amimouse_lasty = joy0dat >> 8;
+
+	error = request_irq(IRQ_AMIGA_VERTB, amimouse_interrupt, 0, "amimouse",
+			    dev);
+	if (error)
+		dev_err(&dev->dev, "Can't allocate irq %d\n", IRQ_AMIGA_VERTB);
+
+	return error;
+}
+
+static void amimouse_close(struct input_dev *dev)
+{
+	free_irq(IRQ_AMIGA_VERTB, dev);
+}
+
+static int __init amimouse_probe(struct platform_device *pdev)
+{
+	int err;
+	struct input_dev *dev;
+
+	dev = input_allocate_device();
+	if (!dev)
+		return -ENOMEM;
+
+	dev->name = pdev->name;
+	dev->phys = "amimouse/input0";
+	dev->id.bustype = BUS_AMIGA;
+	dev->id.vendor = 0x0001;
+	dev->id.product = 0x0002;
+	dev->id.version = 0x0100;
+
+	dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REL);
+	dev->relbit[0] = BIT_MASK(REL_X) | BIT_MASK(REL_Y);
+	dev->keybit[BIT_WORD(BTN_LEFT)] = BIT_MASK(BTN_LEFT) |
+		BIT_MASK(BTN_MIDDLE) | BIT_MASK(BTN_RIGHT);
+	dev->open = amimouse_open;
+	dev->close = amimouse_close;
+	dev->dev.parent = &pdev->dev;
+
+	err = input_register_device(dev);
+	if (err) {
+		input_free_device(dev);
+		return err;
+	}
+
+	platform_set_drvdata(pdev, dev);
+
+	return 0;
+}
+
+static void __exit amimouse_remove(struct platform_device *pdev)
+{
+	struct input_dev *dev = platform_get_drvdata(pdev);
+
+	input_unregister_device(dev);
+}
+
+/*
+ * amimouse_remove() lives in .exit.text. For drivers registered via
+ * module_platform_driver_probe() this is ok because they cannot get unbound at
+ * runtime. So mark the driver struct with __refdata to prevent modpost
+ * triggering a section mismatch warning.
+ */
+static struct platform_driver amimouse_driver __refdata = {
+	.remove = __exit_p(amimouse_remove),
+	.driver   = {
+		.name	= "amiga-mouse",
+	},
+};
+
+module_platform_driver_probe(amimouse_driver, amimouse_probe);
+
+MODULE_ALIAS("platform:amiga-mouse");