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, 284 insertions, 0 deletions

diff --git a/drivers/mfd/rn5t618.c b/drivers/mfd/rn5t618.c
new file mode 100644
index 000000000..23ca00d2c
--- /dev/null
+++ b/drivers/mfd/rn5t618.c
@@ -0,0 +1,284 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MFD core driver for Ricoh RN5T618 PMIC
+ *
+ * Copyright (C) 2014 Beniamino Galvani <b.galvani@gmail.com>
+ * Copyright (C) 2016 Toradex AG
+ */
+
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/rn5t618.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/regmap.h>
+
+static const struct mfd_cell rn5t618_cells[] = {
+	{ .name = "rn5t618-regulator" },
+	{ .name = "rn5t618-wdt" },
+};
+
+static const struct mfd_cell rc5t619_cells[] = {
+	{ .name = "rn5t618-adc" },
+	{ .name = "rn5t618-power" },
+	{ .name = "rn5t618-regulator" },
+	{ .name = "rc5t619-rtc" },
+	{ .name = "rn5t618-wdt" },
+};
+
+static bool rn5t618_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case RN5T618_WATCHDOGCNT:
+	case RN5T618_DCIRQ:
+	case RN5T618_ILIMDATAH ... RN5T618_AIN0DATAL:
+	case RN5T618_ADCCNT3:
+	case RN5T618_IR_ADC1 ... RN5T618_IR_ADC3:
+	case RN5T618_IR_GPR:
+	case RN5T618_IR_GPF:
+	case RN5T618_MON_IOIN:
+	case RN5T618_INTMON:
+	case RN5T618_RTC_CTRL1 ... RN5T618_RTC_CTRL2:
+	case RN5T618_RTC_SECONDS ... RN5T618_RTC_YEAR:
+	case RN5T618_CHGCTL1:
+	case RN5T618_REGISET1 ... RN5T618_REGISET2:
+	case RN5T618_CHGSTATE:
+	case RN5T618_CHGCTRL_IRR ... RN5T618_CHGERR_MONI:
+	case RN5T618_GCHGDET:
+	case RN5T618_CONTROL ... RN5T618_CC_AVEREG0:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config rn5t618_regmap_config = {
+	.reg_bits	= 8,
+	.val_bits	= 8,
+	.volatile_reg	= rn5t618_volatile_reg,
+	.max_register	= RN5T618_MAX_REG,
+	.cache_type	= REGCACHE_MAPLE,
+};
+
+static const struct regmap_irq rc5t619_irqs[] = {
+	REGMAP_IRQ_REG(RN5T618_IRQ_SYS, 0, BIT(0)),
+	REGMAP_IRQ_REG(RN5T618_IRQ_DCDC, 0, BIT(1)),
+	REGMAP_IRQ_REG(RN5T618_IRQ_RTC, 0, BIT(2)),
+	REGMAP_IRQ_REG(RN5T618_IRQ_ADC, 0, BIT(3)),
+	REGMAP_IRQ_REG(RN5T618_IRQ_GPIO, 0, BIT(4)),
+	REGMAP_IRQ_REG(RN5T618_IRQ_CHG, 0, BIT(6)),
+};
+
+static const struct regmap_irq_chip rc5t619_irq_chip = {
+	.name = "rc5t619",
+	.irqs = rc5t619_irqs,
+	.num_irqs = ARRAY_SIZE(rc5t619_irqs),
+	.num_regs = 1,
+	.status_base = RN5T618_INTMON,
+	.unmask_base = RN5T618_INTEN,
+};
+
+static struct i2c_client *rn5t618_pm_power_off;
+static struct notifier_block rn5t618_restart_handler;
+
+static int rn5t618_irq_init(struct rn5t618 *rn5t618)
+{
+	const struct regmap_irq_chip *irq_chip = NULL;
+	int ret;
+
+	if (!rn5t618->irq)
+		return 0;
+
+	switch (rn5t618->variant) {
+	case RC5T619:
+		irq_chip = &rc5t619_irq_chip;
+		break;
+	default:
+		dev_err(rn5t618->dev, "Currently no IRQ support for variant %d\n",
+			(int)rn5t618->variant);
+		return -ENOENT;
+	}
+
+	ret = devm_regmap_add_irq_chip(rn5t618->dev, rn5t618->regmap,
+				       rn5t618->irq,
+				       IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+				       0, irq_chip, &rn5t618->irq_data);
+	if (ret)
+		dev_err(rn5t618->dev, "Failed to register IRQ chip\n");
+
+	return ret;
+}
+
+static void rn5t618_trigger_poweroff_sequence(bool repower)
+{
+	int ret;
+
+	/* disable automatic repower-on */
+	ret = i2c_smbus_read_byte_data(rn5t618_pm_power_off, RN5T618_REPCNT);
+	if (ret < 0)
+		goto err;
+
+	ret &= ~RN5T618_REPCNT_REPWRON;
+	if (repower)
+		ret |= RN5T618_REPCNT_REPWRON;
+
+	ret = i2c_smbus_write_byte_data(rn5t618_pm_power_off,
+					RN5T618_REPCNT, (u8)ret);
+	if (ret < 0)
+		goto err;
+
+	/* start power-off sequence */
+	ret = i2c_smbus_read_byte_data(rn5t618_pm_power_off, RN5T618_SLPCNT);
+	if (ret < 0)
+		goto err;
+
+	ret |= RN5T618_SLPCNT_SWPWROFF;
+
+	ret = i2c_smbus_write_byte_data(rn5t618_pm_power_off,
+					RN5T618_SLPCNT, (u8)ret);
+	if (ret < 0)
+		goto err;
+
+	return;
+
+err:
+	dev_alert(&rn5t618_pm_power_off->dev, "Failed to shutdown (err = %d)\n", ret);
+}
+
+static void rn5t618_power_off(void)
+{
+	rn5t618_trigger_poweroff_sequence(false);
+}
+
+static int rn5t618_restart(struct notifier_block *this,
+			    unsigned long mode, void *cmd)
+{
+	rn5t618_trigger_poweroff_sequence(true);
+
+	/*
+	 * Re-power factor detection on PMIC side is not instant. 1ms
+	 * proved to be enough time until reset takes effect.
+	 */
+	mdelay(1);
+
+	return NOTIFY_DONE;
+}
+
+static const struct of_device_id rn5t618_of_match[] = {
+	{ .compatible = "ricoh,rn5t567", .data = (void *)RN5T567 },
+	{ .compatible = "ricoh,rn5t618", .data = (void *)RN5T618 },
+	{ .compatible = "ricoh,rc5t619", .data = (void *)RC5T619 },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, rn5t618_of_match);
+
+static int rn5t618_i2c_probe(struct i2c_client *i2c)
+{
+	struct rn5t618 *priv;
+	int ret;
+
+	priv = devm_kzalloc(&i2c->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	i2c_set_clientdata(i2c, priv);
+	priv->variant = (long)i2c_get_match_data(i2c);
+	priv->irq = i2c->irq;
+	priv->dev = &i2c->dev;
+
+	priv->regmap = devm_regmap_init_i2c(i2c, &rn5t618_regmap_config);
+	if (IS_ERR(priv->regmap)) {
+		ret = PTR_ERR(priv->regmap);
+		dev_err(&i2c->dev, "regmap init failed: %d\n", ret);
+		return ret;
+	}
+
+	if (priv->variant == RC5T619)
+		ret = devm_mfd_add_devices(&i2c->dev, PLATFORM_DEVID_NONE,
+					   rc5t619_cells,
+					   ARRAY_SIZE(rc5t619_cells),
+					   NULL, 0, NULL);
+	else
+		ret = devm_mfd_add_devices(&i2c->dev, PLATFORM_DEVID_NONE,
+					   rn5t618_cells,
+					   ARRAY_SIZE(rn5t618_cells),
+					   NULL, 0, NULL);
+	if (ret) {
+		dev_err(&i2c->dev, "failed to add sub-devices: %d\n", ret);
+		return ret;
+	}
+
+	rn5t618_pm_power_off = i2c;
+	if (of_device_is_system_power_controller(i2c->dev.of_node)) {
+		if (!pm_power_off)
+			pm_power_off = rn5t618_power_off;
+		else
+			dev_warn(&i2c->dev, "Poweroff callback already assigned\n");
+	}
+
+	rn5t618_restart_handler.notifier_call = rn5t618_restart;
+	rn5t618_restart_handler.priority = 192;
+
+	ret = register_restart_handler(&rn5t618_restart_handler);
+	if (ret) {
+		dev_err(&i2c->dev, "cannot register restart handler, %d\n", ret);
+		return ret;
+	}
+
+	return rn5t618_irq_init(priv);
+}
+
+static void rn5t618_i2c_remove(struct i2c_client *i2c)
+{
+	if (i2c == rn5t618_pm_power_off) {
+		rn5t618_pm_power_off = NULL;
+		pm_power_off = NULL;
+	}
+
+	unregister_restart_handler(&rn5t618_restart_handler);
+}
+
+static int __maybe_unused rn5t618_i2c_suspend(struct device *dev)
+{
+	struct rn5t618 *priv = dev_get_drvdata(dev);
+
+	if (priv->irq)
+		disable_irq(priv->irq);
+
+	return 0;
+}
+
+static int __maybe_unused rn5t618_i2c_resume(struct device *dev)
+{
+	struct rn5t618 *priv = dev_get_drvdata(dev);
+
+	if (priv->irq)
+		enable_irq(priv->irq);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(rn5t618_i2c_dev_pm_ops,
+			rn5t618_i2c_suspend,
+			rn5t618_i2c_resume);
+
+static struct i2c_driver rn5t618_i2c_driver = {
+	.driver = {
+		.name = "rn5t618",
+		.of_match_table = rn5t618_of_match,
+		.pm = &rn5t618_i2c_dev_pm_ops,
+	},
+	.probe = rn5t618_i2c_probe,
+	.remove = rn5t618_i2c_remove,
+};
+
+module_i2c_driver(rn5t618_i2c_driver);
+
+MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>");
+MODULE_DESCRIPTION("Ricoh RN5T567/618 MFD driver");
+MODULE_LICENSE("GPL v2");