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, 261 insertions, 0 deletions

diff --git a/drivers/iio/accel/mc3230.c b/drivers/iio/accel/mc3230.c
new file mode 100644
index 000000000..b45897210
--- /dev/null
+++ b/drivers/iio/accel/mc3230.c
@@ -0,0 +1,261 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * mCube MC3230 3-Axis Accelerometer
+ *
+ * Copyright (c) 2016 Hans de Goede <hdegoede@redhat.com>
+ *
+ * IIO driver for mCube MC3230; 7-bit I2C address: 0x4c.
+ */
+
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define MC3230_REG_XOUT			0x00
+#define MC3230_REG_YOUT			0x01
+#define MC3230_REG_ZOUT			0x02
+
+#define MC3230_REG_MODE			0x07
+#define MC3230_MODE_OPCON_MASK		0x03
+#define MC3230_MODE_OPCON_WAKE		0x01
+#define MC3230_MODE_OPCON_STANDBY	0x03
+
+#define MC3230_REG_CHIP_ID		0x18
+#define MC3230_REG_PRODUCT_CODE		0x3b
+
+/*
+ * The accelerometer has one measurement range:
+ *
+ * -1.5g - +1.5g (8-bit, signed)
+ *
+ */
+
+struct mc3230_chip_info {
+	const char *name;
+	const u8 chip_id;
+	const u8 product_code;
+	const int scale;
+};
+
+static const struct mc3230_chip_info mc3230_chip_info = {
+	.name = "mc3230",
+	.chip_id = 0x01,
+	.product_code = 0x19,
+	/* (1.5 + 1.5) * 9.81 / (2^8 - 1) = 0.115411765 */
+	.scale = 115411765,
+};
+
+static const struct mc3230_chip_info mc3510c_chip_info = {
+	.name = "mc3510c",
+	.chip_id = 0x23,
+	.product_code = 0x10,
+	/* Was obtained empirically */
+	.scale = 625000000,
+};
+
+#define MC3230_CHANNEL(reg, axis) {	\
+	.type = IIO_ACCEL,	\
+	.address = reg,	\
+	.modified = 1,	\
+	.channel2 = IIO_MOD_##axis,	\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+	.ext_info = mc3230_ext_info, \
+}
+
+struct mc3230_data {
+	const struct mc3230_chip_info *chip_info;
+	struct i2c_client *client;
+	struct iio_mount_matrix orientation;
+};
+
+static const struct iio_mount_matrix *
+mc3230_get_mount_matrix(const struct iio_dev *indio_dev,
+			const struct iio_chan_spec *chan)
+{
+	struct mc3230_data *data = iio_priv(indio_dev);
+
+	return &data->orientation;
+}
+
+static const struct iio_chan_spec_ext_info mc3230_ext_info[] = {
+	IIO_MOUNT_MATRIX(IIO_SHARED_BY_DIR, mc3230_get_mount_matrix),
+	{ }
+};
+
+static const struct iio_chan_spec mc3230_channels[] = {
+	MC3230_CHANNEL(MC3230_REG_XOUT, X),
+	MC3230_CHANNEL(MC3230_REG_YOUT, Y),
+	MC3230_CHANNEL(MC3230_REG_ZOUT, Z),
+};
+
+static int mc3230_set_opcon(struct mc3230_data *data, int opcon)
+{
+	int ret;
+	struct i2c_client *client = data->client;
+
+	ret = i2c_smbus_read_byte_data(client, MC3230_REG_MODE);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to read mode reg: %d\n", ret);
+		return ret;
+	}
+
+	ret &= ~MC3230_MODE_OPCON_MASK;
+	ret |= opcon;
+
+	ret = i2c_smbus_write_byte_data(client, MC3230_REG_MODE, ret);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to write mode reg: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int mc3230_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan,
+				int *val, int *val2, long mask)
+{
+	struct mc3230_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = i2c_smbus_read_byte_data(data->client, chan->address);
+		if (ret < 0)
+			return ret;
+		*val = sign_extend32(ret, 7);
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0;
+		*val2 = data->chip_info->scale;
+		return IIO_VAL_INT_PLUS_NANO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info mc3230_info = {
+	.read_raw	= mc3230_read_raw,
+};
+
+static int mc3230_probe(struct i2c_client *client)
+{
+	int ret;
+	struct iio_dev *indio_dev;
+	struct mc3230_data *data;
+	const struct mc3230_chip_info *chip_info;
+
+	chip_info = i2c_get_match_data(client);
+	if (chip_info == NULL) {
+		dev_err(&client->dev, "failed to get match data");
+		return -ENODATA;
+	}
+
+	/* First check chip-id and product-id */
+	ret = i2c_smbus_read_byte_data(client, MC3230_REG_CHIP_ID);
+	if (ret != chip_info->chip_id) {
+		dev_info(&client->dev,
+			"chip id check fail: 0x%x != 0x%x !\n",
+			ret, chip_info->chip_id);
+	}
+
+	ret = i2c_smbus_read_byte_data(client, MC3230_REG_PRODUCT_CODE);
+	if (ret != chip_info->product_code) {
+		dev_info(&client->dev,
+			"product code check fail: 0x%x != 0x%x !\n",
+			ret, chip_info->product_code);
+	}
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	data->chip_info = chip_info;
+	data->client = client;
+	i2c_set_clientdata(client, indio_dev);
+
+	indio_dev->info = &mc3230_info;
+	indio_dev->name = chip_info->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = mc3230_channels;
+	indio_dev->num_channels = ARRAY_SIZE(mc3230_channels);
+
+	ret = mc3230_set_opcon(data, MC3230_MODE_OPCON_WAKE);
+	if (ret < 0)
+		return ret;
+
+	ret = iio_read_mount_matrix(&client->dev, &data->orientation);
+	if (ret)
+		return ret;
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0) {
+		dev_err(&client->dev, "device_register failed\n");
+		mc3230_set_opcon(data, MC3230_MODE_OPCON_STANDBY);
+	}
+
+	return ret;
+}
+
+static void mc3230_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+	iio_device_unregister(indio_dev);
+
+	mc3230_set_opcon(iio_priv(indio_dev), MC3230_MODE_OPCON_STANDBY);
+}
+
+static int mc3230_suspend(struct device *dev)
+{
+	struct mc3230_data *data;
+
+	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
+
+	return mc3230_set_opcon(data, MC3230_MODE_OPCON_STANDBY);
+}
+
+static int mc3230_resume(struct device *dev)
+{
+	struct mc3230_data *data;
+
+	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
+
+	return mc3230_set_opcon(data, MC3230_MODE_OPCON_WAKE);
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(mc3230_pm_ops, mc3230_suspend, mc3230_resume);
+
+static const struct i2c_device_id mc3230_i2c_id[] = {
+	{ .name = "mc3230", .driver_data = (kernel_ulong_t)&mc3230_chip_info },
+	{ .name = "mc3510c", .driver_data = (kernel_ulong_t)&mc3510c_chip_info },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, mc3230_i2c_id);
+
+static const struct of_device_id mc3230_of_match[] = {
+	{ .compatible = "mcube,mc3230", &mc3230_chip_info },
+	{ .compatible = "mcube,mc3510c", &mc3510c_chip_info },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mc3230_of_match);
+
+static struct i2c_driver mc3230_driver = {
+	.driver = {
+		.name = "mc3230",
+		.of_match_table = mc3230_of_match,
+		.pm = pm_sleep_ptr(&mc3230_pm_ops),
+	},
+	.probe		= mc3230_probe,
+	.remove		= mc3230_remove,
+	.id_table	= mc3230_i2c_id,
+};
+
+module_i2c_driver(mc3230_driver);
+
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
+MODULE_DESCRIPTION("mCube MC3230 3-Axis Accelerometer driver");
+MODULE_LICENSE("GPL v2");