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, 278 insertions, 0 deletions

diff --git a/drivers/mfd/max77686.c b/drivers/mfd/max77686.c
new file mode 100644
index 000000000..0118a444a
--- /dev/null
+++ b/drivers/mfd/max77686.c
@@ -0,0 +1,278 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// max77686.c - mfd core driver for the Maxim 77686/802
+//
+// Copyright (C) 2012 Samsung Electronics
+// Chiwoong Byun <woong.byun@samsung.com>
+// Jonghwa Lee <jonghwa3.lee@samsung.com>
+//
+//This driver is based on max8997.c
+
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/pm_runtime.h>
+#include <linux/module.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/max77686.h>
+#include <linux/mfd/max77686-private.h>
+#include <linux/err.h>
+#include <linux/of.h>
+
+static const struct mfd_cell max77686_devs[] = {
+	{ .name = "max77686-pmic", },
+	{ .name = "max77686-rtc", },
+	{ .name = "max77686-clk", },
+};
+
+static const struct mfd_cell max77802_devs[] = {
+	{ .name = "max77802-pmic", },
+	{ .name = "max77802-clk", },
+	{ .name = "max77802-rtc", },
+};
+
+static bool max77802_pmic_is_accessible_reg(struct device *dev,
+					    unsigned int reg)
+{
+	return reg < MAX77802_REG_PMIC_END;
+}
+
+static bool max77802_rtc_is_accessible_reg(struct device *dev,
+					   unsigned int reg)
+{
+	return (reg >= MAX77802_RTC_INT && reg < MAX77802_RTC_END);
+}
+
+static bool max77802_is_accessible_reg(struct device *dev, unsigned int reg)
+{
+	return (max77802_pmic_is_accessible_reg(dev, reg) ||
+		max77802_rtc_is_accessible_reg(dev, reg));
+}
+
+static bool max77802_pmic_is_precious_reg(struct device *dev, unsigned int reg)
+{
+	return (reg == MAX77802_REG_INTSRC || reg == MAX77802_REG_INT1 ||
+		reg == MAX77802_REG_INT2);
+}
+
+static bool max77802_rtc_is_precious_reg(struct device *dev, unsigned int reg)
+{
+	return (reg == MAX77802_RTC_INT ||
+		reg == MAX77802_RTC_UPDATE0 ||
+		reg == MAX77802_RTC_UPDATE1);
+}
+
+static bool max77802_is_precious_reg(struct device *dev, unsigned int reg)
+{
+	return (max77802_pmic_is_precious_reg(dev, reg) ||
+		max77802_rtc_is_precious_reg(dev, reg));
+}
+
+static bool max77802_pmic_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	return (max77802_is_precious_reg(dev, reg) ||
+		reg == MAX77802_REG_STATUS1 || reg == MAX77802_REG_STATUS2 ||
+		reg == MAX77802_REG_PWRON);
+}
+
+static bool max77802_rtc_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	return (max77802_rtc_is_precious_reg(dev, reg) ||
+		reg == MAX77802_RTC_SEC ||
+		reg == MAX77802_RTC_MIN ||
+		reg == MAX77802_RTC_HOUR ||
+		reg == MAX77802_RTC_WEEKDAY ||
+		reg == MAX77802_RTC_MONTH ||
+		reg == MAX77802_RTC_YEAR ||
+		reg == MAX77802_RTC_MONTHDAY);
+}
+
+static bool max77802_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	return (max77802_pmic_is_volatile_reg(dev, reg) ||
+		max77802_rtc_is_volatile_reg(dev, reg));
+}
+
+static const struct regmap_config max77686_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static const struct regmap_config max77802_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.writeable_reg = max77802_is_accessible_reg,
+	.readable_reg = max77802_is_accessible_reg,
+	.precious_reg = max77802_is_precious_reg,
+	.volatile_reg = max77802_is_volatile_reg,
+	.name = "max77802-pmic",
+	.cache_type = REGCACHE_MAPLE,
+};
+
+static const struct regmap_irq max77686_irqs[] = {
+	/* INT1 interrupts */
+	{ .reg_offset = 0, .mask = MAX77686_INT1_PWRONF_MSK, },
+	{ .reg_offset = 0, .mask = MAX77686_INT1_PWRONR_MSK, },
+	{ .reg_offset = 0, .mask = MAX77686_INT1_JIGONBF_MSK, },
+	{ .reg_offset = 0, .mask = MAX77686_INT1_JIGONBR_MSK, },
+	{ .reg_offset = 0, .mask = MAX77686_INT1_ACOKBF_MSK, },
+	{ .reg_offset = 0, .mask = MAX77686_INT1_ACOKBR_MSK, },
+	{ .reg_offset = 0, .mask = MAX77686_INT1_ONKEY1S_MSK, },
+	{ .reg_offset = 0, .mask = MAX77686_INT1_MRSTB_MSK, },
+	/* INT2 interrupts */
+	{ .reg_offset = 1, .mask = MAX77686_INT2_140C_MSK, },
+	{ .reg_offset = 1, .mask = MAX77686_INT2_120C_MSK, },
+};
+
+static const struct regmap_irq_chip max77686_irq_chip = {
+	.name			= "max77686-pmic",
+	.status_base		= MAX77686_REG_INT1,
+	.mask_base		= MAX77686_REG_INT1MSK,
+	.num_regs		= 2,
+	.irqs			= max77686_irqs,
+	.num_irqs		= ARRAY_SIZE(max77686_irqs),
+};
+
+static const struct regmap_irq_chip max77802_irq_chip = {
+	.name			= "max77802-pmic",
+	.status_base		= MAX77802_REG_INT1,
+	.mask_base		= MAX77802_REG_INT1MSK,
+	.num_regs		= 2,
+	.irqs			= max77686_irqs, /* same masks as 77686 */
+	.num_irqs		= ARRAY_SIZE(max77686_irqs),
+};
+
+static const struct of_device_id max77686_pmic_dt_match[] = {
+	{
+		.compatible = "maxim,max77686",
+		.data = (void *)TYPE_MAX77686,
+	},
+	{
+		.compatible = "maxim,max77802",
+		.data = (void *)TYPE_MAX77802,
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, max77686_pmic_dt_match);
+
+static int max77686_i2c_probe(struct i2c_client *i2c)
+{
+	struct max77686_dev *max77686 = NULL;
+	unsigned int data;
+	int ret = 0;
+	const struct regmap_config *config;
+	const struct regmap_irq_chip *irq_chip;
+	const struct mfd_cell *cells;
+	int n_devs;
+
+	max77686 = devm_kzalloc(&i2c->dev,
+				sizeof(struct max77686_dev), GFP_KERNEL);
+	if (!max77686)
+		return -ENOMEM;
+
+	i2c_set_clientdata(i2c, max77686);
+	max77686->type = (unsigned long)of_device_get_match_data(&i2c->dev);
+	max77686->dev = &i2c->dev;
+	max77686->i2c = i2c;
+
+	max77686->irq = i2c->irq;
+
+	if (max77686->type == TYPE_MAX77686) {
+		config = &max77686_regmap_config;
+		irq_chip = &max77686_irq_chip;
+		cells =  max77686_devs;
+		n_devs = ARRAY_SIZE(max77686_devs);
+	} else {
+		config = &max77802_regmap_config;
+		irq_chip = &max77802_irq_chip;
+		cells =  max77802_devs;
+		n_devs = ARRAY_SIZE(max77802_devs);
+	}
+
+	max77686->regmap = devm_regmap_init_i2c(i2c, config);
+	if (IS_ERR(max77686->regmap)) {
+		ret = PTR_ERR(max77686->regmap);
+		dev_err(max77686->dev, "Failed to allocate register map: %d\n",
+				ret);
+		return ret;
+	}
+
+	ret = regmap_read(max77686->regmap, MAX77686_REG_DEVICE_ID, &data);
+	if (ret < 0) {
+		dev_err(max77686->dev,
+			"device not found on this channel (this is not an error)\n");
+		return -ENODEV;
+	}
+
+	ret = devm_regmap_add_irq_chip(&i2c->dev, max77686->regmap,
+				       max77686->irq,
+				       IRQF_ONESHOT | IRQF_SHARED, 0, irq_chip,
+				       &max77686->irq_data);
+	if (ret < 0) {
+		dev_err(&i2c->dev, "failed to add PMIC irq chip: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_mfd_add_devices(max77686->dev, -1, cells, n_devs, NULL,
+				   0, NULL);
+	if (ret < 0) {
+		dev_err(&i2c->dev, "failed to add MFD devices: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int max77686_suspend(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct max77686_dev *max77686 = i2c_get_clientdata(i2c);
+
+	if (device_may_wakeup(dev))
+		enable_irq_wake(max77686->irq);
+
+	/*
+	 * IRQ must be disabled during suspend because if it happens
+	 * while suspended it will be handled before resuming I2C.
+	 *
+	 * When device is woken up from suspend (e.g. by RTC wake alarm),
+	 * an interrupt occurs before resuming I2C bus controller.
+	 * Interrupt handler tries to read registers but this read
+	 * will fail because I2C is still suspended.
+	 */
+	disable_irq(max77686->irq);
+
+	return 0;
+}
+
+static int max77686_resume(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct max77686_dev *max77686 = i2c_get_clientdata(i2c);
+
+	if (device_may_wakeup(dev))
+		disable_irq_wake(max77686->irq);
+
+	enable_irq(max77686->irq);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(max77686_pm, max77686_suspend, max77686_resume);
+
+static struct i2c_driver max77686_i2c_driver = {
+	.driver = {
+		   .name = "max77686",
+		   .pm = pm_sleep_ptr(&max77686_pm),
+		   .of_match_table = max77686_pmic_dt_match,
+	},
+	.probe = max77686_i2c_probe,
+};
+
+module_i2c_driver(max77686_i2c_driver);
+
+MODULE_DESCRIPTION("MAXIM 77686/802 multi-function core driver");
+MODULE_AUTHOR("Chiwoong Byun <woong.byun@samsung.com>");
+MODULE_LICENSE("GPL");