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, 346 insertions, 0 deletions

diff --git a/drivers/mfd/adp5520.c b/drivers/mfd/adp5520.c
new file mode 100644
index 000000000..bd6f4965e
--- /dev/null
+++ b/drivers/mfd/adp5520.c
@@ -0,0 +1,346 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Base driver for Analog Devices ADP5520/ADP5501 MFD PMICs
+ * LCD Backlight: drivers/video/backlight/adp5520_bl
+ * LEDs		: drivers/led/leds-adp5520
+ * GPIO		: drivers/gpio/adp5520-gpio (ADP5520 only)
+ * Keys		: drivers/input/keyboard/adp5520-keys (ADP5520 only)
+ *
+ * Copyright 2009 Analog Devices Inc.
+ *
+ * Author: Michael Hennerich <michael.hennerich@analog.com>
+ *
+ * Derived from da903x:
+ * Copyright (C) 2008 Compulab, Ltd.
+ *	Mike Rapoport <mike@compulab.co.il>
+ *
+ * Copyright (C) 2006-2008 Marvell International Ltd.
+ *	Eric Miao <eric.miao@marvell.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+
+#include <linux/mfd/adp5520.h>
+
+struct adp5520_chip {
+	struct i2c_client *client;
+	struct device *dev;
+	struct mutex lock;
+	struct blocking_notifier_head notifier_list;
+	int irq;
+	unsigned long id;
+	uint8_t mode;
+};
+
+static int __adp5520_read(struct i2c_client *client,
+				int reg, uint8_t *val)
+{
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(client, reg);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed reading at 0x%02x\n", reg);
+		return ret;
+	}
+
+	*val = (uint8_t)ret;
+	return 0;
+}
+
+static int __adp5520_write(struct i2c_client *client,
+				 int reg, uint8_t val)
+{
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(client, reg, val);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed writing 0x%02x to 0x%02x\n",
+				val, reg);
+		return ret;
+	}
+	return 0;
+}
+
+static int __adp5520_ack_bits(struct i2c_client *client, int reg,
+			      uint8_t bit_mask)
+{
+	struct adp5520_chip *chip = i2c_get_clientdata(client);
+	uint8_t reg_val;
+	int ret;
+
+	mutex_lock(&chip->lock);
+
+	ret = __adp5520_read(client, reg, &reg_val);
+
+	if (!ret) {
+		reg_val |= bit_mask;
+		ret = __adp5520_write(client, reg, reg_val);
+	}
+
+	mutex_unlock(&chip->lock);
+	return ret;
+}
+
+int adp5520_write(struct device *dev, int reg, uint8_t val)
+{
+	return __adp5520_write(to_i2c_client(dev), reg, val);
+}
+EXPORT_SYMBOL_GPL(adp5520_write);
+
+int adp5520_read(struct device *dev, int reg, uint8_t *val)
+{
+	return __adp5520_read(to_i2c_client(dev), reg, val);
+}
+EXPORT_SYMBOL_GPL(adp5520_read);
+
+int adp5520_set_bits(struct device *dev, int reg, uint8_t bit_mask)
+{
+	struct adp5520_chip *chip = dev_get_drvdata(dev);
+	uint8_t reg_val;
+	int ret;
+
+	mutex_lock(&chip->lock);
+
+	ret = __adp5520_read(chip->client, reg, &reg_val);
+
+	if (!ret && ((reg_val & bit_mask) != bit_mask)) {
+		reg_val |= bit_mask;
+		ret = __adp5520_write(chip->client, reg, reg_val);
+	}
+
+	mutex_unlock(&chip->lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(adp5520_set_bits);
+
+int adp5520_clr_bits(struct device *dev, int reg, uint8_t bit_mask)
+{
+	struct adp5520_chip *chip = dev_get_drvdata(dev);
+	uint8_t reg_val;
+	int ret;
+
+	mutex_lock(&chip->lock);
+
+	ret = __adp5520_read(chip->client, reg, &reg_val);
+
+	if (!ret && (reg_val & bit_mask)) {
+		reg_val &= ~bit_mask;
+		ret = __adp5520_write(chip->client, reg, reg_val);
+	}
+
+	mutex_unlock(&chip->lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(adp5520_clr_bits);
+
+int adp5520_register_notifier(struct device *dev, struct notifier_block *nb,
+				unsigned int events)
+{
+	struct adp5520_chip *chip = dev_get_drvdata(dev);
+
+	if (chip->irq) {
+		adp5520_set_bits(chip->dev, ADP5520_INTERRUPT_ENABLE,
+			events & (ADP5520_KP_IEN | ADP5520_KR_IEN |
+			ADP5520_OVP_IEN | ADP5520_CMPR_IEN));
+
+		return blocking_notifier_chain_register(&chip->notifier_list,
+			 nb);
+	}
+
+	return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(adp5520_register_notifier);
+
+int adp5520_unregister_notifier(struct device *dev, struct notifier_block *nb,
+				unsigned int events)
+{
+	struct adp5520_chip *chip = dev_get_drvdata(dev);
+
+	adp5520_clr_bits(chip->dev, ADP5520_INTERRUPT_ENABLE,
+		events & (ADP5520_KP_IEN | ADP5520_KR_IEN |
+		ADP5520_OVP_IEN | ADP5520_CMPR_IEN));
+
+	return blocking_notifier_chain_unregister(&chip->notifier_list, nb);
+}
+EXPORT_SYMBOL_GPL(adp5520_unregister_notifier);
+
+static irqreturn_t adp5520_irq_thread(int irq, void *data)
+{
+	struct adp5520_chip *chip = data;
+	unsigned int events;
+	uint8_t reg_val;
+	int ret;
+
+	ret = __adp5520_read(chip->client, ADP5520_MODE_STATUS, &reg_val);
+	if (ret)
+		goto out;
+
+	events =  reg_val & (ADP5520_OVP_INT | ADP5520_CMPR_INT |
+		ADP5520_GPI_INT | ADP5520_KR_INT | ADP5520_KP_INT);
+
+	blocking_notifier_call_chain(&chip->notifier_list, events, NULL);
+	/* ACK, Sticky bits are W1C */
+	__adp5520_ack_bits(chip->client, ADP5520_MODE_STATUS, events);
+
+out:
+	return IRQ_HANDLED;
+}
+
+static int __remove_subdev(struct device *dev, void *unused)
+{
+	platform_device_unregister(to_platform_device(dev));
+	return 0;
+}
+
+static int adp5520_remove_subdevs(struct adp5520_chip *chip)
+{
+	return device_for_each_child(chip->dev, NULL, __remove_subdev);
+}
+
+static int adp5520_probe(struct i2c_client *client)
+{
+	const struct i2c_device_id *id = i2c_client_get_device_id(client);
+	struct adp5520_platform_data *pdata = dev_get_platdata(&client->dev);
+	struct platform_device *pdev;
+	struct adp5520_chip *chip;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter,
+					I2C_FUNC_SMBUS_BYTE_DATA)) {
+		dev_err(&client->dev, "SMBUS Word Data not Supported\n");
+		return -EIO;
+	}
+
+	if (pdata == NULL) {
+		dev_err(&client->dev, "missing platform data\n");
+		return -ENODEV;
+	}
+
+	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, chip);
+	chip->client = client;
+
+	chip->dev = &client->dev;
+	chip->irq = client->irq;
+	chip->id = id->driver_data;
+	mutex_init(&chip->lock);
+
+	if (chip->irq) {
+		BLOCKING_INIT_NOTIFIER_HEAD(&chip->notifier_list);
+
+		ret = request_threaded_irq(chip->irq, NULL, adp5520_irq_thread,
+				IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+				"adp5520", chip);
+		if (ret) {
+			dev_err(&client->dev, "failed to request irq %d\n",
+					chip->irq);
+			return ret;
+		}
+	}
+
+	ret = adp5520_write(chip->dev, ADP5520_MODE_STATUS, ADP5520_nSTNBY);
+	if (ret) {
+		dev_err(&client->dev, "failed to write\n");
+		goto out_free_irq;
+	}
+
+	if (pdata->keys) {
+		pdev = platform_device_register_data(chip->dev, "adp5520-keys",
+				chip->id, pdata->keys, sizeof(*pdata->keys));
+		if (IS_ERR(pdev)) {
+			ret = PTR_ERR(pdev);
+			goto out_remove_subdevs;
+		}
+	}
+
+	if (pdata->gpio) {
+		pdev = platform_device_register_data(chip->dev, "adp5520-gpio",
+				chip->id, pdata->gpio, sizeof(*pdata->gpio));
+		if (IS_ERR(pdev)) {
+			ret = PTR_ERR(pdev);
+			goto out_remove_subdevs;
+		}
+	}
+
+	if (pdata->leds) {
+		pdev = platform_device_register_data(chip->dev, "adp5520-led",
+				chip->id, pdata->leds, sizeof(*pdata->leds));
+		if (IS_ERR(pdev)) {
+			ret = PTR_ERR(pdev);
+			goto out_remove_subdevs;
+		}
+	}
+
+	if (pdata->backlight) {
+		pdev = platform_device_register_data(chip->dev,
+						"adp5520-backlight",
+						chip->id,
+						pdata->backlight,
+						sizeof(*pdata->backlight));
+		if (IS_ERR(pdev)) {
+			ret = PTR_ERR(pdev);
+			goto out_remove_subdevs;
+		}
+	}
+
+	return 0;
+
+out_remove_subdevs:
+	adp5520_remove_subdevs(chip);
+
+out_free_irq:
+	if (chip->irq)
+		free_irq(chip->irq, chip);
+
+	return ret;
+}
+
+static int adp5520_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct adp5520_chip *chip = dev_get_drvdata(&client->dev);
+
+	adp5520_read(chip->dev, ADP5520_MODE_STATUS, &chip->mode);
+	/* All other bits are W1C */
+	chip->mode &= ADP5520_BL_EN | ADP5520_DIM_EN | ADP5520_nSTNBY;
+	adp5520_write(chip->dev, ADP5520_MODE_STATUS, 0);
+	return 0;
+}
+
+static int adp5520_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct adp5520_chip *chip = dev_get_drvdata(&client->dev);
+
+	adp5520_write(chip->dev, ADP5520_MODE_STATUS, chip->mode);
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(adp5520_pm, adp5520_suspend, adp5520_resume);
+
+static const struct i2c_device_id adp5520_id[] = {
+	{ "pmic-adp5520", ID_ADP5520 },
+	{ "pmic-adp5501", ID_ADP5501 },
+	{ }
+};
+
+static struct i2c_driver adp5520_driver = {
+	.driver = {
+		.name			= "adp5520",
+		.pm			= pm_sleep_ptr(&adp5520_pm),
+		.suppress_bind_attrs	= true,
+	},
+	.probe		= adp5520_probe,
+	.id_table	= adp5520_id,
+};
+builtin_i2c_driver(adp5520_driver);