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, 191 insertions, 0 deletions

diff --git a/drivers/input/joystick/stinger.c b/drivers/input/joystick/stinger.c
new file mode 100644
index 000000000..011f9b137
--- /dev/null
+++ b/drivers/input/joystick/stinger.c
@@ -0,0 +1,191 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (c) 2000-2001 Vojtech Pavlik
+ *  Copyright (c) 2000 Mark Fletcher
+ */
+
+/*
+ * Gravis Stinger gamepad driver for Linux
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/serio.h>
+
+#define DRIVER_DESC	"Gravis Stinger gamepad driver"
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+/*
+ * Constants.
+ */
+
+#define STINGER_MAX_LENGTH 8
+
+/*
+ * Per-Stinger data.
+ */
+
+struct stinger {
+	struct input_dev *dev;
+	int idx;
+	unsigned char data[STINGER_MAX_LENGTH];
+	char phys[32];
+};
+
+/*
+ * stinger_process_packet() decodes packets the driver receives from the
+ * Stinger. It updates the data accordingly.
+ */
+
+static void stinger_process_packet(struct stinger *stinger)
+{
+	struct input_dev *dev = stinger->dev;
+	unsigned char *data = stinger->data;
+
+	if (!stinger->idx) return;
+
+	input_report_key(dev, BTN_A,	  ((data[0] & 0x20) >> 5));
+	input_report_key(dev, BTN_B,	  ((data[0] & 0x10) >> 4));
+	input_report_key(dev, BTN_C,	  ((data[0] & 0x08) >> 3));
+	input_report_key(dev, BTN_X,	  ((data[0] & 0x04) >> 2));
+	input_report_key(dev, BTN_Y,	  ((data[3] & 0x20) >> 5));
+	input_report_key(dev, BTN_Z,	  ((data[3] & 0x10) >> 4));
+	input_report_key(dev, BTN_TL,     ((data[3] & 0x08) >> 3));
+	input_report_key(dev, BTN_TR,     ((data[3] & 0x04) >> 2));
+	input_report_key(dev, BTN_SELECT, ((data[3] & 0x02) >> 1));
+	input_report_key(dev, BTN_START,   (data[3] & 0x01));
+
+	input_report_abs(dev, ABS_X, (data[1] & 0x3F) - ((data[0] & 0x01) << 6));
+	input_report_abs(dev, ABS_Y, ((data[0] & 0x02) << 5) - (data[2] & 0x3F));
+
+	input_sync(dev);
+
+	return;
+}
+
+/*
+ * stinger_interrupt() is called by the low level driver when characters
+ * are ready for us. We then buffer them for further processing, or call the
+ * packet processing routine.
+ */
+
+static irqreturn_t stinger_interrupt(struct serio *serio,
+	unsigned char data, unsigned int flags)
+{
+	struct stinger *stinger = serio_get_drvdata(serio);
+
+	/* All Stinger packets are 4 bytes */
+
+	if (stinger->idx < STINGER_MAX_LENGTH)
+		stinger->data[stinger->idx++] = data;
+
+	if (stinger->idx == 4) {
+		stinger_process_packet(stinger);
+		stinger->idx = 0;
+	}
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * stinger_disconnect() is the opposite of stinger_connect()
+ */
+
+static void stinger_disconnect(struct serio *serio)
+{
+	struct stinger *stinger = serio_get_drvdata(serio);
+
+	serio_close(serio);
+	serio_set_drvdata(serio, NULL);
+	input_unregister_device(stinger->dev);
+	kfree(stinger);
+}
+
+/*
+ * stinger_connect() is the routine that is called when someone adds a
+ * new serio device that supports Stinger protocol and registers it as
+ * an input device.
+ */
+
+static int stinger_connect(struct serio *serio, struct serio_driver *drv)
+{
+	struct stinger *stinger;
+	struct input_dev *input_dev;
+	int err = -ENOMEM;
+
+	stinger = kmalloc_obj(*stinger);
+	input_dev = input_allocate_device();
+	if (!stinger || !input_dev)
+		goto fail1;
+
+	stinger->dev = input_dev;
+	snprintf(stinger->phys, sizeof(stinger->phys), "%s/serio0", serio->phys);
+
+	input_dev->name = "Gravis Stinger";
+	input_dev->phys = stinger->phys;
+	input_dev->id.bustype = BUS_RS232;
+	input_dev->id.vendor = SERIO_STINGER;
+	input_dev->id.product = 0x0001;
+	input_dev->id.version = 0x0100;
+	input_dev->dev.parent = &serio->dev;
+
+	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
+	input_dev->keybit[BIT_WORD(BTN_A)] = BIT_MASK(BTN_A) | BIT_MASK(BTN_B) |
+		BIT_MASK(BTN_C) | BIT_MASK(BTN_X) | BIT_MASK(BTN_Y) |
+		BIT_MASK(BTN_Z) | BIT_MASK(BTN_TL) | BIT_MASK(BTN_TR) |
+		BIT_MASK(BTN_START) | BIT_MASK(BTN_SELECT);
+	input_set_abs_params(input_dev, ABS_X, -64, 64, 0, 4);
+	input_set_abs_params(input_dev, ABS_Y, -64, 64, 0, 4);
+
+	serio_set_drvdata(serio, stinger);
+
+	err = serio_open(serio, drv);
+	if (err)
+		goto fail2;
+
+	err = input_register_device(stinger->dev);
+	if (err)
+		goto fail3;
+
+	return 0;
+
+ fail3:	serio_close(serio);
+ fail2:	serio_set_drvdata(serio, NULL);
+ fail1:	input_free_device(input_dev);
+	kfree(stinger);
+	return err;
+}
+
+/*
+ * The serio driver structure.
+ */
+
+static const struct serio_device_id stinger_serio_ids[] = {
+	{
+		.type	= SERIO_RS232,
+		.proto	= SERIO_STINGER,
+		.id	= SERIO_ANY,
+		.extra	= SERIO_ANY,
+	},
+	{ 0 }
+};
+
+MODULE_DEVICE_TABLE(serio, stinger_serio_ids);
+
+static struct serio_driver stinger_drv = {
+	.driver		= {
+		.name	= "stinger",
+	},
+	.description	= DRIVER_DESC,
+	.id_table	= stinger_serio_ids,
+	.interrupt	= stinger_interrupt,
+	.connect	= stinger_connect,
+	.disconnect	= stinger_disconnect,
+};
+
+module_serio_driver(stinger_drv);