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, 415 insertions, 0 deletions

diff --git a/drivers/input/keyboard/qt2160.c b/drivers/input/keyboard/qt2160.c
new file mode 100644
index 000000000..e64adaca1
--- /dev/null
+++ b/drivers/input/keyboard/qt2160.c
@@ -0,0 +1,415 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  qt2160.c - Atmel AT42QT2160 Touch Sense Controller
+ *
+ *  Copyright (C) 2009 Raphael Derosso Pereira <raphaelpereira@gmail.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/jiffies.h>
+#include <linux/i2c.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/input.h>
+
+#define QT2160_VALID_CHIPID  0x11
+
+#define QT2160_CMD_CHIPID     0
+#define QT2160_CMD_CODEVER    1
+#define QT2160_CMD_GSTAT      2
+#define QT2160_CMD_KEYS3      3
+#define QT2160_CMD_KEYS4      4
+#define QT2160_CMD_SLIDE      5
+#define QT2160_CMD_GPIOS      6
+#define QT2160_CMD_SUBVER     7
+#define QT2160_CMD_CALIBRATE  10
+#define QT2160_CMD_DRIVE_X    70
+#define QT2160_CMD_PWMEN_X    74
+#define QT2160_CMD_PWM_DUTY   76
+
+#define QT2160_NUM_LEDS_X	8
+
+#define QT2160_CYCLE_INTERVAL	2000 /* msec - 2 sec */
+
+static unsigned char qt2160_key2code[] = {
+	KEY_0, KEY_1, KEY_2, KEY_3,
+	KEY_4, KEY_5, KEY_6, KEY_7,
+	KEY_8, KEY_9, KEY_A, KEY_B,
+	KEY_C, KEY_D, KEY_E, KEY_F,
+};
+
+#ifdef CONFIG_LEDS_CLASS
+struct qt2160_led {
+	struct qt2160_data *qt2160;
+	struct led_classdev cdev;
+	char name[32];
+	int id;
+	enum led_brightness brightness;
+};
+#endif
+
+struct qt2160_data {
+	struct i2c_client *client;
+	struct input_dev *input;
+	unsigned short keycodes[ARRAY_SIZE(qt2160_key2code)];
+	u16 key_matrix;
+#ifdef CONFIG_LEDS_CLASS
+	struct qt2160_led leds[QT2160_NUM_LEDS_X];
+#endif
+};
+
+static int qt2160_read(struct i2c_client *client, u8 reg);
+static int qt2160_write(struct i2c_client *client, u8 reg, u8 data);
+
+#ifdef CONFIG_LEDS_CLASS
+
+static int qt2160_led_set(struct led_classdev *cdev,
+			  enum led_brightness value)
+{
+	struct qt2160_led *led = container_of(cdev, struct qt2160_led, cdev);
+	struct qt2160_data *qt2160 = led->qt2160;
+	struct i2c_client *client = qt2160->client;
+	u32 drive, pwmen;
+
+	if (value != led->brightness) {
+		drive = qt2160_read(client, QT2160_CMD_DRIVE_X);
+		pwmen = qt2160_read(client, QT2160_CMD_PWMEN_X);
+		if (value != LED_OFF) {
+			drive |= BIT(led->id);
+			pwmen |= BIT(led->id);
+
+		} else {
+			drive &= ~BIT(led->id);
+			pwmen &= ~BIT(led->id);
+		}
+		qt2160_write(client, QT2160_CMD_DRIVE_X, drive);
+		qt2160_write(client, QT2160_CMD_PWMEN_X, pwmen);
+
+		/*
+		 * Changing this register will change the brightness
+		 * of every LED in the qt2160. It's a HW limitation.
+		 */
+		if (value != LED_OFF)
+			qt2160_write(client, QT2160_CMD_PWM_DUTY, value);
+
+		led->brightness = value;
+	}
+
+	return 0;
+}
+
+#endif /* CONFIG_LEDS_CLASS */
+
+static int qt2160_read_block(struct i2c_client *client,
+			     u8 inireg, u8 *buffer, unsigned int count)
+{
+	int error, idx = 0;
+
+	/*
+	 * Can't use SMBus block data read. Check for I2C functionality to speed
+	 * things up whenever possible. Otherwise we will be forced to read
+	 * sequentially.
+	 */
+	if (i2c_check_functionality(client->adapter, I2C_FUNC_I2C))	{
+
+		error = i2c_smbus_write_byte(client, inireg + idx);
+		if (error) {
+			dev_err(&client->dev,
+				"couldn't send request. Returned %d\n", error);
+			return error;
+		}
+
+		error = i2c_master_recv(client, buffer, count);
+		if (error != count) {
+			dev_err(&client->dev,
+				"couldn't read registers. Returned %d bytes\n", error);
+			return error;
+		}
+	} else {
+
+		while (count--) {
+			int data;
+
+			error = i2c_smbus_write_byte(client, inireg + idx);
+			if (error) {
+				dev_err(&client->dev,
+					"couldn't send request. Returned %d\n", error);
+				return error;
+			}
+
+			data = i2c_smbus_read_byte(client);
+			if (data < 0) {
+				dev_err(&client->dev,
+					"couldn't read register. Returned %d\n", data);
+				return data;
+			}
+
+			buffer[idx++] = data;
+		}
+	}
+
+	return 0;
+}
+
+static void qt2160_get_key_matrix(struct input_dev *input)
+{
+	struct qt2160_data *qt2160 = input_get_drvdata(input);
+	struct i2c_client *client = qt2160->client;
+	u8 regs[6];
+	u16 old_matrix, new_matrix;
+	int ret, i, mask;
+
+	dev_dbg(&client->dev, "requesting keys...\n");
+
+	/*
+	 * Read all registers from General Status Register
+	 * to GPIOs register
+	 */
+	ret = qt2160_read_block(client, QT2160_CMD_GSTAT, regs, 6);
+	if (ret) {
+		dev_err(&client->dev,
+			"could not perform chip read.\n");
+		return;
+	}
+
+	old_matrix = qt2160->key_matrix;
+	qt2160->key_matrix = new_matrix = (regs[2] << 8) | regs[1];
+
+	mask = 0x01;
+	for (i = 0; i < 16; ++i, mask <<= 1) {
+		int keyval = new_matrix & mask;
+
+		if ((old_matrix & mask) != keyval) {
+			input_report_key(input, qt2160->keycodes[i], keyval);
+			dev_dbg(&client->dev, "key %d %s\n",
+				i, keyval ? "pressed" : "released");
+		}
+	}
+
+	input_sync(input);
+}
+
+static irqreturn_t qt2160_irq(int irq, void *data)
+{
+	struct input_dev *input = data;
+
+	qt2160_get_key_matrix(input);
+
+	return IRQ_HANDLED;
+}
+
+static int qt2160_read(struct i2c_client *client, u8 reg)
+{
+	int ret;
+
+	ret = i2c_smbus_write_byte(client, reg);
+	if (ret) {
+		dev_err(&client->dev,
+			"couldn't send request. Returned %d\n", ret);
+		return ret;
+	}
+
+	ret = i2c_smbus_read_byte(client);
+	if (ret < 0) {
+		dev_err(&client->dev,
+			"couldn't read register. Returned %d\n", ret);
+		return ret;
+	}
+
+	return ret;
+}
+
+static int qt2160_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,
+			"couldn't write data. Returned %d\n", ret);
+
+	return ret;
+}
+
+#ifdef CONFIG_LEDS_CLASS
+
+static int qt2160_register_leds(struct qt2160_data *qt2160)
+{
+	struct i2c_client *client = qt2160->client;
+	int error;
+	int i;
+
+	for (i = 0; i < QT2160_NUM_LEDS_X; i++) {
+		struct qt2160_led *led = &qt2160->leds[i];
+
+		snprintf(led->name, sizeof(led->name), "qt2160:x%d", i);
+		led->cdev.name = led->name;
+		led->cdev.brightness_set_blocking = qt2160_led_set;
+		led->cdev.brightness = LED_OFF;
+		led->id = i;
+		led->qt2160 = qt2160;
+
+		error = devm_led_classdev_register(&client->dev, &led->cdev);
+		if (error)
+			return error;
+	}
+
+	/* Tur off LEDs */
+	qt2160_write(client, QT2160_CMD_DRIVE_X, 0);
+	qt2160_write(client, QT2160_CMD_PWMEN_X, 0);
+	qt2160_write(client, QT2160_CMD_PWM_DUTY, 0);
+
+	return 0;
+}
+
+#else
+
+static inline int qt2160_register_leds(struct qt2160_data *qt2160)
+{
+	return 0;
+}
+
+#endif
+
+static bool qt2160_identify(struct i2c_client *client)
+{
+	int id, ver, rev;
+
+	/* Read Chid ID to check if chip is valid */
+	id = qt2160_read(client, QT2160_CMD_CHIPID);
+	if (id != QT2160_VALID_CHIPID) {
+		dev_err(&client->dev, "ID %d not supported\n", id);
+		return false;
+	}
+
+	/* Read chip firmware version */
+	ver = qt2160_read(client, QT2160_CMD_CODEVER);
+	if (ver < 0) {
+		dev_err(&client->dev, "could not get firmware version\n");
+		return false;
+	}
+
+	/* Read chip firmware revision */
+	rev = qt2160_read(client, QT2160_CMD_SUBVER);
+	if (rev < 0) {
+		dev_err(&client->dev, "could not get firmware revision\n");
+		return false;
+	}
+
+	dev_info(&client->dev, "AT42QT2160 firmware version %d.%d.%d\n",
+			ver >> 4, ver & 0xf, rev);
+
+	return true;
+}
+
+static int qt2160_probe(struct i2c_client *client)
+{
+	struct qt2160_data *qt2160;
+	struct input_dev *input;
+	int i;
+	int error;
+
+	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 (!qt2160_identify(client))
+		return -ENODEV;
+
+	/* Chip is valid and active. Allocate structure */
+	qt2160 = devm_kzalloc(&client->dev, sizeof(*qt2160), GFP_KERNEL);
+	if (!qt2160)
+		return -ENOMEM;
+
+	input = devm_input_allocate_device(&client->dev);
+	if (!input)
+		return -ENOMEM;
+
+	qt2160->client = client;
+	qt2160->input = input;
+
+	input->name = "AT42QT2160 Touch Sense Keyboard";
+	input->id.bustype = BUS_I2C;
+
+	input->keycode = qt2160->keycodes;
+	input->keycodesize = sizeof(qt2160->keycodes[0]);
+	input->keycodemax = ARRAY_SIZE(qt2160_key2code);
+
+	__set_bit(EV_KEY, input->evbit);
+	__clear_bit(EV_REP, input->evbit);
+	for (i = 0; i < ARRAY_SIZE(qt2160_key2code); i++) {
+		qt2160->keycodes[i] = qt2160_key2code[i];
+		__set_bit(qt2160_key2code[i], input->keybit);
+	}
+	__clear_bit(KEY_RESERVED, input->keybit);
+
+	input_set_drvdata(input, qt2160);
+
+	/* Calibrate device */
+	error = qt2160_write(client, QT2160_CMD_CALIBRATE, 1);
+	if (error) {
+		dev_err(&client->dev, "failed to calibrate device\n");
+		return error;
+	}
+
+	if (client->irq) {
+		error = devm_request_threaded_irq(&client->dev, client->irq,
+						  NULL, qt2160_irq,
+						  IRQF_ONESHOT,
+						  "qt2160", input);
+		if (error) {
+			dev_err(&client->dev,
+				"failed to allocate irq %d\n", client->irq);
+			return error;
+		}
+	} else {
+		error = input_setup_polling(input, qt2160_get_key_matrix);
+		if (error) {
+			dev_err(&client->dev, "Failed to setup polling\n");
+			return error;
+		}
+		input_set_poll_interval(input, QT2160_CYCLE_INTERVAL);
+	}
+
+	error = qt2160_register_leds(qt2160);
+	if (error) {
+		dev_err(&client->dev, "Failed to register leds\n");
+		return error;
+	}
+
+	error = input_register_device(qt2160->input);
+	if (error) {
+		dev_err(&client->dev,
+			"Failed to register input device\n");
+		return error;
+	}
+
+	return 0;
+}
+
+static const struct i2c_device_id qt2160_idtable[] = {
+	{ .name = "qt2160" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(i2c, qt2160_idtable);
+
+static struct i2c_driver qt2160_driver = {
+	.driver = {
+		.name	= "qt2160",
+	},
+
+	.id_table	= qt2160_idtable,
+	.probe		= qt2160_probe,
+};
+
+module_i2c_driver(qt2160_driver);
+
+MODULE_AUTHOR("Raphael Derosso Pereira <raphaelpereira@gmail.com>");
+MODULE_DESCRIPTION("Driver for AT42QT2160 Touch Sensor");
+MODULE_LICENSE("GPL");