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, 490 insertions, 0 deletions

diff --git a/drivers/iio/dac/max22007.c b/drivers/iio/dac/max22007.c
new file mode 100644
index 000000000..e2c7e2ad3
--- /dev/null
+++ b/drivers/iio/dac/max22007.c
@@ -0,0 +1,490 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * max22007.c - MAX22007 DAC driver
+ *
+ * Driver for Analog Devices MAX22007 Digital to Analog Converter.
+ *
+ * Copyright (c) 2026 Analog Devices Inc.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/crc8.h>
+#include <linux/delay.h>
+#include <linux/dev_printk.h>
+#include <linux/device/devres.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/gpio/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/kstrtox.h>
+#include <linux/minmax.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/types.h>
+
+#include <dt-bindings/iio/addac/adi,ad74413r.h>
+struct device;
+
+#define MAX22007_NUM_CHANNELS				4
+#define MAX22007_REV_ID_REG				0x00
+#define MAX22007_STAT_INTR_REG				0x01
+#define MAX22007_INTERRUPT_EN_REG			0x02
+#define MAX22007_CONFIG_REG				0x03
+#define MAX22007_CONTROL_REG				0x04
+#define MAX22007_CHANNEL_MODE_REG			0x05
+#define MAX22007_SOFT_RESET_REG				0x06
+#define MAX22007_DAC_CHANNEL_REG(ch)			(0x07 + (ch))
+#define MAX22007_GPIO_CTRL_REG				0x0B
+#define MAX22007_GPIO_DATA_REG				0x0C
+#define MAX22007_GPI_EDGE_INT_CTRL_REG			0x0D
+#define MAX22007_GPI_INT_STATUS_REG			0x0E
+
+/* Channel mask definitions */
+#define     MAX22007_CH_MODE_CH_MASK(ch)		BIT(12 + (ch))
+#define     MAX22007_CH_PWRON_CH_MASK(ch)		BIT(8 + (ch))
+#define     MAX22007_DAC_LATCH_MODE_MASK(ch)		BIT(12 + (ch))
+#define     MAX22007_LDAC_UPDATE_MASK(ch)		BIT(12 + (ch))
+#define     MAX22007_SW_RST_MASK			BIT(8)
+#define     MAX22007_SW_CLR_MASK			BIT(12)
+#define     MAX22007_SOFT_RESET_BITS_MASK		(MAX22007_SW_RST_MASK | \
+							 MAX22007_SW_CLR_MASK)
+#define     MAX22007_DAC_DATA_MASK			GENMASK(15, 4)
+#define     MAX22007_DAC_MAX_RAW			GENMASK(11, 0)
+#define     MAX22007_CRC8_POLYNOMIAL			0x8C
+#define     MAX22007_CRC_EN_MASK			BIT(0)
+#define     MAX22007_RW_MASK				BIT(0)
+#define     MAX22007_CRC_OVERHEAD			1
+#define     MAX22007_NUM_SUPPLIES			3
+#define     MAX22007_REF_MV				2500
+
+/* Field value preparation macros with masking */
+#define     MAX22007_CH_PWR_VAL(ch, val)		(((val) & 0x1) << (8 + (ch)))
+#define     MAX22007_CH_MODE_VAL(ch, val)		(((val) & 0x1) << (12 + (ch)))
+#define     MAX22007_DAC_LATCH_MODE_VAL(ch, val)	(((val) & 0x1) << (12 + (ch)))
+
+static u8 max22007_crc8_table[CRC8_TABLE_SIZE];
+
+static const char * const max22007_supply_names[MAX22007_NUM_SUPPLIES] = {
+	"vdd",
+	"hvdd",
+	"hvss",
+};
+
+struct max22007_state {
+	struct spi_device *spi;
+	struct regmap *regmap;
+	struct iio_chan_spec *iio_chans;
+	u8 tx_buf[4] __aligned(IIO_DMA_MINALIGN);
+	u8 rx_buf[4];
+};
+
+static int max22007_spi_read(void *context, const void *reg, size_t reg_size,
+			     void *val, size_t val_size)
+{
+	struct max22007_state *st = context;
+	u8 calculated_crc, received_crc;
+	u8 rx_buf[4];
+	u8 reg_byte;
+	int ret;
+
+	if (reg_size != 1)
+		return -EINVAL;
+
+	if (val_size == 0 || val_size > 3)
+		return -EINVAL;
+
+	memcpy(&reg_byte, reg, 1);
+
+	ret = spi_write_then_read(st->spi, &reg_byte, 1, rx_buf,
+				  val_size + MAX22007_CRC_OVERHEAD);
+	if (ret) {
+		dev_err(&st->spi->dev, "SPI transfer failed: %d\n", ret);
+		return ret;
+	}
+
+	calculated_crc = crc8(max22007_crc8_table, &reg_byte, 1, 0x00);
+	calculated_crc = crc8(max22007_crc8_table, rx_buf, 2, calculated_crc);
+	received_crc = rx_buf[val_size];
+
+	if (calculated_crc != received_crc) {
+		dev_err(&st->spi->dev, "CRC mismatch on read register %02x\n", reg_byte);
+		return -EIO;
+	}
+
+	memcpy(val, rx_buf, val_size);
+
+	return 0;
+}
+
+static int max22007_spi_write(void *context, const void *data, size_t count)
+{
+	struct max22007_state *st = context;
+	struct spi_transfer xfer = {
+		.tx_buf = st->tx_buf,
+		.rx_buf = st->rx_buf,
+	};
+
+	if (count + MAX22007_CRC_OVERHEAD > sizeof(st->tx_buf))
+		return -EINVAL;
+
+	memset(st->tx_buf, 0, sizeof(st->tx_buf));
+
+	xfer.len = count + MAX22007_CRC_OVERHEAD;
+
+	memcpy(st->tx_buf, data, count);
+	st->tx_buf[count] = crc8(max22007_crc8_table, st->tx_buf,
+				 sizeof(st->tx_buf) - 1, 0x00);
+
+	return spi_sync_transfer(st->spi, &xfer, 1);
+}
+
+static bool max22007_reg_readable(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MAX22007_REV_ID_REG:
+	case MAX22007_STAT_INTR_REG:
+	case MAX22007_CONFIG_REG:
+	case MAX22007_CONTROL_REG:
+	case MAX22007_CHANNEL_MODE_REG:
+	case MAX22007_SOFT_RESET_REG:
+	case MAX22007_GPIO_CTRL_REG:
+	case MAX22007_GPIO_DATA_REG:
+	case MAX22007_GPI_EDGE_INT_CTRL_REG:
+	case MAX22007_GPI_INT_STATUS_REG:
+		return true;
+	case MAX22007_DAC_CHANNEL_REG(0) ... MAX22007_DAC_CHANNEL_REG(MAX22007_NUM_CHANNELS - 1):
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool max22007_reg_writable(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MAX22007_CONFIG_REG:
+	case MAX22007_CONTROL_REG:
+	case MAX22007_CHANNEL_MODE_REG:
+	case MAX22007_SOFT_RESET_REG:
+	case MAX22007_GPIO_CTRL_REG:
+	case MAX22007_GPIO_DATA_REG:
+	case MAX22007_GPI_EDGE_INT_CTRL_REG:
+		return true;
+	case MAX22007_DAC_CHANNEL_REG(0) ... MAX22007_DAC_CHANNEL_REG(MAX22007_NUM_CHANNELS - 1):
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_bus max22007_regmap_bus = {
+	.read = max22007_spi_read,
+	.write = max22007_spi_write,
+	.read_flag_mask = MAX22007_RW_MASK,
+	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
+	.val_format_endian_default = REGMAP_ENDIAN_BIG,
+};
+
+static const struct regmap_config max22007_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 16,
+	.reg_shift = -1,
+	.readable_reg = max22007_reg_readable,
+	.writeable_reg = max22007_reg_writable,
+	.max_register = 0x0E,
+};
+
+static int max22007_write_channel_data(struct max22007_state *st,
+				       unsigned int channel, int data)
+{
+	unsigned int reg_val;
+
+	if (data < 0 || data > MAX22007_DAC_MAX_RAW)
+		return -EINVAL;
+
+	reg_val = FIELD_PREP(MAX22007_DAC_DATA_MASK, data);
+
+	return regmap_write(st->regmap, MAX22007_DAC_CHANNEL_REG(channel), reg_val);
+}
+
+static int max22007_read_channel_data(struct max22007_state *st,
+				      unsigned int channel, int *data)
+{
+	unsigned int reg_val;
+	int ret;
+
+	ret = regmap_read(st->regmap, MAX22007_DAC_CHANNEL_REG(channel), &reg_val);
+	if (ret)
+		return ret;
+
+	*data = FIELD_GET(MAX22007_DAC_DATA_MASK, reg_val);
+
+	return 0;
+}
+
+static int max22007_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct max22007_state *st = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = max22007_read_channel_data(st, chan->channel, val);
+		if (ret)
+			return ret;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		if (chan->type == IIO_VOLTAGE)
+			*val = 5 * MAX22007_REF_MV;  /* 5 * Vref in mV */
+		else
+			*val = 25;  /* Vref / (2 * Rsense) = MAX22007_REF_MV / 100 */
+		*val2 = 12;  /* 12-bit DAC resolution */
+		return IIO_VAL_FRACTIONAL_LOG2;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int max22007_write_raw(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      int val, int val2, long mask)
+{
+	struct max22007_state *st = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		return max22007_write_channel_data(st, chan->channel, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info max22007_info = {
+	.read_raw = max22007_read_raw,
+	.write_raw = max22007_write_raw,
+};
+
+static ssize_t max22007_read_dac_powerdown(struct iio_dev *indio_dev,
+					   uintptr_t private,
+					   const struct iio_chan_spec *chan,
+					   char *buf)
+{
+	struct max22007_state *st = iio_priv(indio_dev);
+	unsigned int reg_val;
+	bool powerdown;
+	int ret;
+
+	ret = regmap_read(st->regmap, MAX22007_CHANNEL_MODE_REG, &reg_val);
+	if (ret)
+		return ret;
+
+	powerdown = !(reg_val & MAX22007_CH_PWRON_CH_MASK(chan->channel));
+
+	return sysfs_emit(buf, "%d\n", powerdown);
+}
+
+static ssize_t max22007_write_dac_powerdown(struct iio_dev *indio_dev,
+					    uintptr_t private,
+					    const struct iio_chan_spec *chan,
+					    const char *buf, size_t len)
+{
+	struct max22007_state *st = iio_priv(indio_dev);
+	bool powerdown;
+	int ret;
+
+	ret = kstrtobool(buf, &powerdown);
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(st->regmap, MAX22007_CHANNEL_MODE_REG,
+				 MAX22007_CH_PWRON_CH_MASK(chan->channel),
+				 MAX22007_CH_PWR_VAL(chan->channel, powerdown ? 0 : 1));
+	if (ret)
+		return ret;
+
+	return len;
+}
+
+static const struct iio_chan_spec_ext_info max22007_ext_info[] = {
+	{
+		.name = "powerdown",
+		.read = max22007_read_dac_powerdown,
+		.write = max22007_write_dac_powerdown,
+		.shared = IIO_SEPARATE,
+	},
+	{ }
+};
+
+static int max22007_parse_channel_cfg(struct max22007_state *st, u8 *num_channels)
+{
+	struct device *dev = &st->spi->dev;
+	int ret, num_chan;
+	int i = 0;
+	u32 reg;
+
+	num_chan = device_get_child_node_count(dev);
+	if (!num_chan)
+		return dev_err_probe(dev, -ENODEV, "no channels configured\n");
+
+	st->iio_chans = devm_kcalloc(dev, num_chan, sizeof(*st->iio_chans), GFP_KERNEL);
+	if (!st->iio_chans)
+		return -ENOMEM;
+
+	device_for_each_child_node_scoped(dev, child) {
+		u32 ch_func;
+		enum iio_chan_type chan_type;
+
+		ret = fwnode_property_read_u32(child, "reg", &reg);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "failed to read reg property of %pfwP\n", child);
+
+		if (reg >= MAX22007_NUM_CHANNELS)
+			return dev_err_probe(dev, -EINVAL,
+					     "reg out of range in %pfwP\n", child);
+
+		ret = fwnode_property_read_u32(child, "adi,ch-func", &ch_func);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "missing adi,ch-func property for %pfwP\n", child);
+
+		switch (ch_func) {
+		case CH_FUNC_VOLTAGE_OUTPUT:
+			chan_type = IIO_VOLTAGE;
+			break;
+		case CH_FUNC_CURRENT_OUTPUT:
+			chan_type = IIO_CURRENT;
+			break;
+		default:
+			return dev_err_probe(dev, -EINVAL,
+					     "invalid adi,ch-func %u for %pfwP\n",
+					     ch_func, child);
+		}
+
+		st->iio_chans[i++] = (struct iio_chan_spec) {
+			.output = 1,
+			.indexed = 1,
+			.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+					      BIT(IIO_CHAN_INFO_SCALE),
+			.ext_info = max22007_ext_info,
+			.channel = reg,
+			.type = chan_type,
+		};
+
+		ret = regmap_update_bits(st->regmap, MAX22007_CHANNEL_MODE_REG,
+					 MAX22007_CH_MODE_CH_MASK(reg),
+					 MAX22007_CH_MODE_VAL(reg, ch_func - 1));
+		if (ret)
+			return ret;
+
+		/* Set DAC to transparent mode (immediate update) */
+		ret = regmap_update_bits(st->regmap, MAX22007_CONFIG_REG,
+					 MAX22007_DAC_LATCH_MODE_MASK(reg),
+					 MAX22007_DAC_LATCH_MODE_VAL(reg, 1));
+		if (ret)
+			return ret;
+	}
+
+	*num_channels = num_chan;
+
+	return 0;
+}
+
+static int max22007_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct gpio_desc *reset_gpio;
+	struct max22007_state *st;
+	struct iio_dev *indio_dev;
+	u8 num_channels;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	st->spi = spi;
+
+	crc8_populate_lsb(max22007_crc8_table, MAX22007_CRC8_POLYNOMIAL);
+
+	st->regmap = devm_regmap_init(dev, &max22007_regmap_bus, st,
+					 &max22007_regmap_config);
+	if (IS_ERR(st->regmap))
+		return dev_err_probe(dev, PTR_ERR(st->regmap),
+				     "Failed to initialize regmap\n");
+
+	ret = devm_regulator_bulk_get_enable(dev, MAX22007_NUM_SUPPLIES,
+					     max22007_supply_names);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to get and enable regulators\n");
+
+	reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(reset_gpio),
+				     "Failed to get reset GPIO\n");
+
+	if (reset_gpio) {
+		gpiod_set_value_cansleep(reset_gpio, 1);
+		usleep_range(1000, 5000);
+		gpiod_set_value_cansleep(reset_gpio, 0);
+		usleep_range(1000, 5000);
+	} else {
+		ret = regmap_write(st->regmap, MAX22007_SOFT_RESET_REG,
+				   MAX22007_SOFT_RESET_BITS_MASK);
+		if (ret)
+			return ret;
+	}
+
+	ret = regmap_set_bits(st->regmap, MAX22007_CONFIG_REG,
+			      MAX22007_CRC_EN_MASK);
+	if (ret)
+		return ret;
+
+	ret = max22007_parse_channel_cfg(st, &num_channels);
+	if (ret)
+		return ret;
+
+	indio_dev->info = &max22007_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = st->iio_chans;
+	indio_dev->num_channels = num_channels;
+	indio_dev->name = "max22007";
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct spi_device_id max22007_id[] = {
+	{ .name = "max22007" },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, max22007_id);
+
+static const struct of_device_id max22007_of_match[] = {
+	{ .compatible = "adi,max22007" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max22007_of_match);
+
+static struct spi_driver max22007_driver = {
+	.driver = {
+		.name = "max22007",
+		.of_match_table = max22007_of_match,
+	},
+	.probe = max22007_probe,
+	.id_table = max22007_id,
+};
+module_spi_driver(max22007_driver);
+
+MODULE_AUTHOR("Janani Sunil <janani.sunil@analog.com>");
+MODULE_DESCRIPTION("Analog Devices MAX22007 DAC");
+MODULE_LICENSE("GPL");