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, 263 insertions, 0 deletions

diff --git a/drivers/input/keyboard/qt1070.c b/drivers/input/keyboard/qt1070.c
new file mode 100644
index 000000000..e31cb115a
--- /dev/null
+++ b/drivers/input/keyboard/qt1070.c
@@ -0,0 +1,263 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Atmel AT42QT1070 QTouch Sensor Controller
+ *
+ *  Copyright (C) 2011 Atmel
+ *
+ *  Authors: Bo Shen <voice.shen@atmel.com>
+ *
+ *  Base on AT42QT2160 driver by:
+ *  Raphael Derosso Pereira <raphaelpereira@gmail.com>
+ *  Copyright (C) 2009
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/slab.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/jiffies.h>
+#include <linux/delay.h>
+
+/* Address for each register */
+#define CHIP_ID            0x00
+#define QT1070_CHIP_ID     0x2E
+
+#define FW_VERSION         0x01
+#define QT1070_FW_VERSION  0x15
+
+#define DET_STATUS         0x02
+
+#define KEY_STATUS         0x03
+
+/* Calibrate */
+#define CALIBRATE_CMD      0x38
+#define QT1070_CAL_TIME    200
+
+/* Reset */
+#define RESET              0x39
+#define QT1070_RESET_TIME  255
+
+/* AT42QT1070 support up to 7 keys */
+static const unsigned short qt1070_key2code[] = {
+	KEY_0, KEY_1, KEY_2, KEY_3,
+	KEY_4, KEY_5, KEY_6,
+};
+
+struct qt1070_data {
+	struct i2c_client *client;
+	struct input_dev *input;
+	unsigned int irq;
+	unsigned short keycodes[ARRAY_SIZE(qt1070_key2code)];
+	u8 last_keys;
+};
+
+static int qt1070_read(struct i2c_client *client, u8 reg)
+{
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(client, reg);
+	if (ret < 0)
+		dev_err(&client->dev,
+			"can not read register, returned %d\n", ret);
+
+	return ret;
+}
+
+static int qt1070_write(struct i2c_client *client, u8 reg, u8 data)
+{
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(client, reg, data);
+	if (ret < 0)
+		dev_err(&client->dev,
+			"can not write register, returned %d\n", ret);
+
+	return ret;
+}
+
+static bool qt1070_identify(struct i2c_client *client)
+{
+	int id, ver;
+
+	/* Read Chip ID */
+	id = qt1070_read(client, CHIP_ID);
+	if (id != QT1070_CHIP_ID) {
+		dev_err(&client->dev, "ID %d not supported\n", id);
+		return false;
+	}
+
+	/* Read firmware version */
+	ver = qt1070_read(client, FW_VERSION);
+	if (ver < 0) {
+		dev_err(&client->dev, "could not read the firmware version\n");
+		return false;
+	}
+
+	dev_info(&client->dev, "AT42QT1070 firmware version %x\n", ver);
+
+	return true;
+}
+
+static irqreturn_t qt1070_interrupt(int irq, void *dev_id)
+{
+	struct qt1070_data *data = dev_id;
+	struct i2c_client *client = data->client;
+	struct input_dev *input = data->input;
+	int i;
+	u8 new_keys, keyval, mask = 0x01;
+
+	/* Read the detected status register, thus clearing interrupt */
+	qt1070_read(client, DET_STATUS);
+
+	/* Read which key changed */
+	new_keys = qt1070_read(client, KEY_STATUS);
+
+	for (i = 0; i < ARRAY_SIZE(qt1070_key2code); i++) {
+		keyval = new_keys & mask;
+		if ((data->last_keys & mask) != keyval)
+			input_report_key(input, data->keycodes[i], keyval);
+		mask <<= 1;
+	}
+	input_sync(input);
+
+	data->last_keys = new_keys;
+	return IRQ_HANDLED;
+}
+
+static int qt1070_probe(struct i2c_client *client)
+{
+	struct qt1070_data *data;
+	struct input_dev *input;
+	int i;
+	int err;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE)) {
+		dev_err(&client->dev, "%s adapter not supported\n",
+			dev_driver_string(&client->adapter->dev));
+		return -ENODEV;
+	}
+
+	if (!client->irq) {
+		dev_err(&client->dev, "please assign the irq to this device\n");
+		return -EINVAL;
+	}
+
+	/* Identify the qt1070 chip */
+	if (!qt1070_identify(client))
+		return -ENODEV;
+
+	data = devm_kzalloc(&client->dev, sizeof(struct qt1070_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	input = devm_input_allocate_device(&client->dev);
+	if (!input)
+		return -ENOMEM;
+
+	data->client = client;
+	data->input = input;
+	data->irq = client->irq;
+
+	input->name = "AT42QT1070 QTouch Sensor";
+	input->id.bustype = BUS_I2C;
+
+	/* Add the keycode */
+	input->keycode = data->keycodes;
+	input->keycodesize = sizeof(data->keycodes[0]);
+	input->keycodemax = ARRAY_SIZE(qt1070_key2code);
+
+	__set_bit(EV_KEY, input->evbit);
+
+	for (i = 0; i < ARRAY_SIZE(qt1070_key2code); i++) {
+		data->keycodes[i] = qt1070_key2code[i];
+		__set_bit(qt1070_key2code[i], input->keybit);
+	}
+
+	/* Calibrate device */
+	qt1070_write(client, CALIBRATE_CMD, 1);
+	msleep(QT1070_CAL_TIME);
+
+	/* Soft reset */
+	qt1070_write(client, RESET, 1);
+	msleep(QT1070_RESET_TIME);
+
+	err = devm_request_threaded_irq(&client->dev, client->irq,
+					NULL, qt1070_interrupt,
+					IRQF_TRIGGER_NONE | IRQF_ONESHOT,
+					client->dev.driver->name, data);
+	if (err) {
+		dev_err(&client->dev, "fail to request irq\n");
+		return err;
+	}
+
+	/* Register the input device */
+	err = input_register_device(data->input);
+	if (err) {
+		dev_err(&client->dev, "Failed to register input device\n");
+		return err;
+	}
+
+	i2c_set_clientdata(client, data);
+
+	/* Read to clear the chang line */
+	qt1070_read(client, DET_STATUS);
+
+	return 0;
+}
+
+static int qt1070_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct qt1070_data *data = i2c_get_clientdata(client);
+
+	if (device_may_wakeup(dev))
+		enable_irq_wake(data->irq);
+
+	return 0;
+}
+
+static int qt1070_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct qt1070_data *data = i2c_get_clientdata(client);
+
+	if (device_may_wakeup(dev))
+		disable_irq_wake(data->irq);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(qt1070_pm_ops, qt1070_suspend, qt1070_resume);
+
+static const struct i2c_device_id qt1070_id[] = {
+	{ .name = "qt1070" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, qt1070_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id qt1070_of_match[] = {
+	{ .compatible = "qt1070", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, qt1070_of_match);
+#endif
+
+static struct i2c_driver qt1070_driver = {
+	.driver	= {
+		.name	= "qt1070",
+		.of_match_table = of_match_ptr(qt1070_of_match),
+		.pm	= pm_sleep_ptr(&qt1070_pm_ops),
+	},
+	.id_table	= qt1070_id,
+	.probe		= qt1070_probe,
+};
+
+module_i2c_driver(qt1070_driver);
+
+MODULE_AUTHOR("Bo Shen <voice.shen@atmel.com>");
+MODULE_DESCRIPTION("Driver for AT42QT1070 QTouch sensor");
+MODULE_LICENSE("GPL");