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, 144 insertions, 0 deletions

diff --git a/drivers/mfd/simple-mfd-i2c.c b/drivers/mfd/simple-mfd-i2c.c
new file mode 100644
index 000000000..ef3ce4bdf
--- /dev/null
+++ b/drivers/mfd/simple-mfd-i2c.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Simple MFD - I2C
+ *
+ * Author(s):
+ * 	Michael Walle <michael@walle.cc>
+ * 	Lee Jones <lee.jones@linaro.org>
+ *
+ * This driver creates a single register map with the intention for it to be
+ * shared by all sub-devices.  Children can use their parent's device structure
+ * (dev.parent) in order to reference it.
+ *
+ * Once the register map has been successfully initialised, any sub-devices
+ * represented by child nodes in Device Tree or via the MFD cells in this file
+ * will be subsequently registered.
+ */
+
+#include <linux/array_size.h>
+#include <linux/dev_printk.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/stddef.h>
+
+#include "simple-mfd-i2c.h"
+
+static const struct regmap_config regmap_config_8r_8v = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static int simple_mfd_i2c_probe(struct i2c_client *i2c)
+{
+	const struct simple_mfd_data *simple_mfd_data;
+	const struct regmap_config *regmap_config;
+	struct regmap *regmap;
+	int ret;
+
+	simple_mfd_data = device_get_match_data(&i2c->dev);
+
+	/* If no regmap_config is specified, use the default 8reg and 8val bits */
+	if (!simple_mfd_data || !simple_mfd_data->regmap_config)
+		regmap_config = &regmap_config_8r_8v;
+	else
+		regmap_config = simple_mfd_data->regmap_config;
+
+	regmap = devm_regmap_init_i2c(i2c, regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	/* If no MFD cells are specified, register using the DT child nodes instead */
+	if (!simple_mfd_data || !simple_mfd_data->mfd_cell)
+		return devm_of_platform_populate(&i2c->dev);
+
+	ret = devm_mfd_add_devices(&i2c->dev, PLATFORM_DEVID_AUTO,
+				   simple_mfd_data->mfd_cell,
+				   simple_mfd_data->mfd_cell_size,
+				   NULL, 0, NULL);
+	if (ret)
+		dev_err(&i2c->dev, "Failed to add child devices\n");
+
+	return ret;
+}
+
+static const struct mfd_cell sy7636a_cells[] = {
+	{ .name = "sy7636a-regulator", },
+	{ .name = "sy7636a-temperature", },
+};
+
+static const struct simple_mfd_data silergy_sy7636a = {
+	.mfd_cell = sy7636a_cells,
+	.mfd_cell_size = ARRAY_SIZE(sy7636a_cells),
+};
+
+static const struct mfd_cell max5970_cells[] = {
+	{ .name = "max5970-regulator", },
+	{ .name = "max5970-iio", },
+	{ .name = "max5970-led", },
+};
+
+static const struct simple_mfd_data maxim_max5970 = {
+	.mfd_cell = max5970_cells,
+	.mfd_cell_size = ARRAY_SIZE(max5970_cells),
+};
+
+static const struct mfd_cell max77705_sensor_cells[] = {
+	{ .name = "max77705-battery" },
+	{ .name = "max77705-hwmon", },
+};
+
+static const struct simple_mfd_data maxim_mon_max77705 = {
+	.mfd_cell = max77705_sensor_cells,
+	.mfd_cell_size = ARRAY_SIZE(max77705_sensor_cells),
+};
+
+static const struct regmap_config spacemit_p1_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static const struct mfd_cell spacemit_p1_cells[] = {
+	{ .name = "spacemit-p1-reboot", },
+	{ .name = "spacemit-p1-regulator", },
+	{ .name = "spacemit-p1-rtc", },
+};
+
+static const struct simple_mfd_data spacemit_p1 = {
+	.regmap_config = &spacemit_p1_regmap_config,
+	.mfd_cell = spacemit_p1_cells,
+	.mfd_cell_size = ARRAY_SIZE(spacemit_p1_cells),
+};
+
+static const struct of_device_id simple_mfd_i2c_of_match[] = {
+	{ .compatible = "delta,tn48m-cpld" },
+	{ .compatible = "fsl,ls1028aqds-fpga" },
+	{ .compatible = "fsl,lx2160aqds-fpga" },
+	{ .compatible = "fsl,lx2160ardb-fpga" },
+	{ .compatible = "kontron,sl28cpld" },
+	{ .compatible = "maxim,max5970", .data = &maxim_max5970 },
+	{ .compatible = "maxim,max5978", .data = &maxim_max5970 },
+	{ .compatible = "maxim,max77705-battery", .data = &maxim_mon_max77705 },
+	{ .compatible = "silergy,sy7636a", .data = &silergy_sy7636a },
+	{ .compatible = "spacemit,p1", .data = &spacemit_p1 },
+	{}
+};
+MODULE_DEVICE_TABLE(of, simple_mfd_i2c_of_match);
+
+static struct i2c_driver simple_mfd_i2c_driver = {
+	.probe = simple_mfd_i2c_probe,
+	.driver = {
+		.name = "simple-mfd-i2c",
+		.of_match_table = simple_mfd_i2c_of_match,
+	},
+};
+module_i2c_driver(simple_mfd_i2c_driver);
+
+MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
+MODULE_DESCRIPTION("Simple MFD - I2C driver");
+MODULE_LICENSE("GPL v2");