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, 133 insertions, 0 deletions

diff --git a/drivers/mfd/rt5033.c b/drivers/mfd/rt5033.c
new file mode 100644
index 000000000..072fd4447
--- /dev/null
+++ b/drivers/mfd/rt5033.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MFD core driver for the Richtek RT5033.
+ *
+ * RT5033 comprises multiple sub-devices switcing charger, fuel gauge,
+ * flash LED, current source, LDO and BUCK regulators.
+ *
+ * Copyright (C) 2014 Samsung Electronics, Co., Ltd.
+ * Author: Beomho Seo <beomho.seo@samsung.com>
+ */
+
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/rt5033.h>
+#include <linux/mfd/rt5033-private.h>
+
+static const struct regmap_irq rt5033_irqs[] = {
+	{ .mask = RT5033_PMIC_IRQ_BUCKOCP, },
+	{ .mask = RT5033_PMIC_IRQ_BUCKLV, },
+	{ .mask = RT5033_PMIC_IRQ_SAFELDOLV, },
+	{ .mask = RT5033_PMIC_IRQ_LDOLV, },
+	{ .mask = RT5033_PMIC_IRQ_OT, },
+	{ .mask = RT5033_PMIC_IRQ_VDDA_UV, },
+};
+
+static const struct regmap_irq_chip rt5033_irq_chip = {
+	.name		= "rt5033",
+	.status_base	= RT5033_REG_PMIC_IRQ_STAT,
+	.unmask_base	= RT5033_REG_PMIC_IRQ_CTRL,
+	.num_regs	= 1,
+	.irqs		= rt5033_irqs,
+	.num_irqs	= ARRAY_SIZE(rt5033_irqs),
+};
+
+static const struct mfd_cell rt5033_devs[] = {
+	{ .name = "rt5033-regulator", },
+	{
+		.name = "rt5033-charger",
+		.of_compatible = "richtek,rt5033-charger",
+	}, {
+		.name = "rt5033-led",
+		.of_compatible = "richtek,rt5033-led",
+	},
+};
+
+static const struct regmap_config rt5033_regmap_config = {
+	.reg_bits	= 8,
+	.val_bits	= 8,
+	.max_register	= RT5033_REG_END,
+};
+
+static int rt5033_i2c_probe(struct i2c_client *i2c)
+{
+	struct rt5033_dev *rt5033;
+	unsigned int dev_id, chip_rev;
+	int ret;
+
+	rt5033 = devm_kzalloc(&i2c->dev, sizeof(*rt5033), GFP_KERNEL);
+	if (!rt5033)
+		return -ENOMEM;
+
+	i2c_set_clientdata(i2c, rt5033);
+	rt5033->dev = &i2c->dev;
+	rt5033->irq = i2c->irq;
+	rt5033->wakeup = true;
+
+	rt5033->regmap = devm_regmap_init_i2c(i2c, &rt5033_regmap_config);
+	if (IS_ERR(rt5033->regmap)) {
+		dev_err(&i2c->dev, "Failed to allocate register map.\n");
+		return PTR_ERR(rt5033->regmap);
+	}
+
+	ret = regmap_read(rt5033->regmap, RT5033_REG_DEVICE_ID, &dev_id);
+	if (ret) {
+		dev_err(&i2c->dev, "Device not found\n");
+		return -ENODEV;
+	}
+	chip_rev = dev_id & RT5033_CHIP_REV_MASK;
+	dev_info(&i2c->dev, "Device found (rev. %d)\n", chip_rev);
+
+	ret = devm_regmap_add_irq_chip(rt5033->dev, rt5033->regmap,
+			rt5033->irq, IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+			0, &rt5033_irq_chip, &rt5033->irq_data);
+	if (ret) {
+		dev_err(&i2c->dev, "Failed to request IRQ %d: %d\n",
+							rt5033->irq, ret);
+		return ret;
+	}
+
+	ret = devm_mfd_add_devices(rt5033->dev, -1, rt5033_devs,
+				   ARRAY_SIZE(rt5033_devs), NULL, 0,
+				   regmap_irq_get_domain(rt5033->irq_data));
+	if (ret < 0) {
+		dev_err(&i2c->dev, "Failed to add RT5033 child devices.\n");
+		return ret;
+	}
+
+	if (rt5033->wakeup) {
+		ret = devm_device_init_wakeup(rt5033->dev);
+		if (ret)
+			return dev_err_probe(rt5033->dev, ret, "Failed to init wakeup\n");
+	}
+
+	return 0;
+}
+
+static const struct i2c_device_id rt5033_i2c_id[] = {
+	{ "rt5033", },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, rt5033_i2c_id);
+
+static const struct of_device_id rt5033_dt_match[] = {
+	{ .compatible = "richtek,rt5033", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, rt5033_dt_match);
+
+static struct i2c_driver rt5033_driver = {
+	.driver = {
+		.name = "rt5033",
+		.of_match_table = rt5033_dt_match,
+	},
+	.probe = rt5033_i2c_probe,
+	.id_table = rt5033_i2c_id,
+};
+module_i2c_driver(rt5033_driver);
+
+MODULE_DESCRIPTION("Richtek RT5033 multi-function core driver");
+MODULE_AUTHOR("Beomho Seo <beomho.seo@samsung.com>");
+MODULE_LICENSE("GPL");