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, 215 insertions, 0 deletions

diff --git a/drivers/regulator/rt4803.c b/drivers/regulator/rt4803.c
new file mode 100644
index 000000000..34cd3f249
--- /dev/null
+++ b/drivers/regulator/rt4803.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2023 Richtek Technology Corp.
+ *
+ * Author: ChiYuan Huang <cy_huang@richtek.com>
+ */
+
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/of_regulator.h>
+
+#define RT4803_AUTO_MODE	1
+#define RT4803_FPWM_MODE	2
+
+#define RT4803_REG_CONFIG	0x01
+#define RT4803_REG_VSELL	0x02
+#define RT4803_REG_VSELH	0x03
+#define RT4803_REG_ILIM		0x04
+#define RT4803_REG_STAT		0x05
+
+#define RT4803_MODE_MASK	GENMASK(1, 0)
+#define RT4803_VSEL_MASK	GENMASK(4, 0)
+#define RT4803_ILIM_MASK	GENMASK(3, 0)
+#define RT4803_TSD_MASK		BIT(7)
+#define RT4803_HOTDIE_MASK	BIT(6)
+#define RT4803_FAULT_MASK	BIT(1)
+#define RT4803_PGOOD_MASK	BIT(0)
+
+#define RT4803_VOUT_MINUV	2850000
+#define RT4803_VOUT_STEPUV	50000
+#define RT4803_VOUT_NUM		32
+
+static int rt4803_set_mode(struct regulator_dev *rdev, unsigned int mode)
+{
+	struct regmap *regmap = rdev_get_regmap(rdev);
+	unsigned int modeval;
+
+	switch (mode) {
+	case REGULATOR_MODE_NORMAL:
+		modeval = RT4803_AUTO_MODE;
+		break;
+	case REGULATOR_MODE_FAST:
+		modeval = RT4803_FPWM_MODE;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	modeval <<= ffs(RT4803_MODE_MASK) - 1;
+
+	return regmap_update_bits(regmap, RT4803_REG_CONFIG, RT4803_MODE_MASK, modeval);
+}
+
+static unsigned int rt4803_get_mode(struct regulator_dev *rdev)
+{
+	struct regmap *regmap = rdev_get_regmap(rdev);
+	unsigned int modeval;
+	int ret;
+
+	ret = regmap_read(regmap, RT4803_REG_CONFIG, &modeval);
+	if (ret)
+		return REGULATOR_MODE_INVALID;
+
+	modeval >>= ffs(RT4803_MODE_MASK) - 1;
+
+	switch (modeval) {
+	case RT4803_AUTO_MODE:
+		return REGULATOR_MODE_NORMAL;
+	case RT4803_FPWM_MODE:
+		return REGULATOR_MODE_FAST;
+	default:
+		return REGULATOR_MODE_INVALID;
+	}
+}
+
+static int rt4803_get_error_flags(struct regulator_dev *rdev, unsigned int *flags)
+{
+	struct regmap *regmap = rdev_get_regmap(rdev);
+	unsigned int state, events = 0;
+	int ret;
+
+	ret = regmap_read(regmap, RT4803_REG_STAT, &state);
+	if (ret)
+		return ret;
+
+	if (state & RT4803_PGOOD_MASK)
+		goto out_error_flag;
+
+	if (state & RT4803_FAULT_MASK)
+		events |= REGULATOR_ERROR_FAIL;
+
+	if (state & RT4803_HOTDIE_MASK)
+		events |= REGULATOR_ERROR_OVER_TEMP_WARN;
+
+	if (state & RT4803_TSD_MASK)
+		events |= REGULATOR_ERROR_OVER_TEMP;
+
+out_error_flag:
+	*flags = events;
+	return 0;
+}
+
+static int rt4803_set_suspend_voltage(struct regulator_dev *rdev, int uV)
+{
+	struct regmap *regmap = rdev_get_regmap(rdev);
+	unsigned int reg, vsel;
+
+	if (rdev->desc->vsel_reg == RT4803_REG_VSELL)
+		reg = RT4803_REG_VSELH;
+	else
+		reg = RT4803_REG_VSELL;
+
+	vsel = (uV - rdev->desc->min_uV) / rdev->desc->uV_step;
+	vsel <<= ffs(RT4803_VSEL_MASK) - 1;
+
+	return regmap_update_bits(regmap, reg, RT4803_VSEL_MASK, vsel);
+}
+
+static const struct regulator_ops rt4803_regulator_ops = {
+	.list_voltage = regulator_list_voltage_linear,
+	.set_voltage_sel = regulator_set_voltage_sel_regmap,
+	.get_voltage_sel = regulator_get_voltage_sel_regmap,
+	.set_mode = rt4803_set_mode,
+	.get_mode = rt4803_get_mode,
+	.get_error_flags = rt4803_get_error_flags,
+	.set_suspend_voltage = rt4803_set_suspend_voltage,
+};
+
+static unsigned int rt4803_of_map_mode(unsigned int mode)
+{
+	switch (mode) {
+	case RT4803_AUTO_MODE:
+		return REGULATOR_MODE_NORMAL;
+	case RT4803_FPWM_MODE:
+		return REGULATOR_MODE_FAST;
+	default:
+		return REGULATOR_MODE_INVALID;
+	}
+}
+
+static const struct regmap_config rt4803_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = RT4803_REG_STAT,
+};
+
+static int rt4803_probe(struct i2c_client *i2c)
+{
+	struct device *dev = &i2c->dev;
+	struct regmap *regmap;
+	struct regulator_desc *desc;
+	struct regulator_config cfg = {};
+	struct regulator_dev *rdev;
+	bool vsel_act_high;
+	int ret;
+
+	desc = devm_kzalloc(dev, sizeof(*desc), GFP_KERNEL);
+	if (!desc)
+		return -ENOMEM;
+
+	regmap = devm_regmap_init_i2c(i2c, &rt4803_regmap_config);
+	if (IS_ERR(regmap))
+		return dev_err_probe(dev, PTR_ERR(regmap), "Failed to init regmap\n");
+
+	/* Always configure the input current limit to max 5A at initial */
+	ret = regmap_update_bits(regmap, RT4803_REG_ILIM, RT4803_ILIM_MASK, 0xff);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to config ILIM to max\n");
+
+	vsel_act_high = device_property_read_bool(dev, "richtek,vsel-active-high");
+
+	desc->name = "rt4803-regulator";
+	desc->type = REGULATOR_VOLTAGE;
+	desc->owner = THIS_MODULE;
+	desc->ops = &rt4803_regulator_ops;
+	desc->min_uV = RT4803_VOUT_MINUV;
+	desc->uV_step = RT4803_VOUT_STEPUV;
+	desc->n_voltages = RT4803_VOUT_NUM;
+	desc->vsel_mask = RT4803_VSEL_MASK;
+	desc->of_map_mode = rt4803_of_map_mode;
+	if (vsel_act_high)
+		desc->vsel_reg = RT4803_REG_VSELH;
+	else
+		desc->vsel_reg = RT4803_REG_VSELL;
+
+	cfg.dev = dev;
+	cfg.of_node = dev_of_node(dev);
+	cfg.init_data = of_get_regulator_init_data(dev, dev_of_node(dev), desc);
+
+	rdev = devm_regulator_register(dev, desc, &cfg);
+	return PTR_ERR_OR_ZERO(rdev);
+}
+
+static const struct of_device_id rt4803_device_match_table[] = {
+	{ .compatible = "richtek,rt4803" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, rt4803_device_match_table);
+
+static struct i2c_driver rt4803_driver = {
+	.driver = {
+		.name = "rt4803",
+		.of_match_table = rt4803_device_match_table,
+	},
+	.probe = rt4803_probe,
+};
+module_i2c_driver(rt4803_driver);
+
+MODULE_DESCRIPTION("Richtek RT4803 voltage regulator driver");
+MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
+MODULE_LICENSE("GPL");