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, 269 insertions, 0 deletions

diff --git a/drivers/iio/frequency/admfm2000.c b/drivers/iio/frequency/admfm2000.c
new file mode 100644
index 000000000..0405b53c5
--- /dev/null
+++ b/drivers/iio/frequency/admfm2000.c
@@ -0,0 +1,269 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ADMFM2000 Dual Microwave Down Converter
+ *
+ * Copyright 2024 Analog Devices Inc.
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+
+#define ADMFM2000_MIXER_MODE		0
+#define ADMFM2000_DIRECT_IF_MODE	1
+#define ADMFM2000_DSA_GPIOS		5
+#define ADMFM2000_MODE_GPIOS		2
+#define ADMFM2000_MAX_GAIN		0
+#define ADMFM2000_MIN_GAIN		-31000
+#define ADMFM2000_DEFAULT_GAIN		-0x20
+
+struct admfm2000_state {
+	struct mutex			lock; /* protect sensor state */
+	struct gpio_desc		*sw1_ch[2];
+	struct gpio_desc		*sw2_ch[2];
+	struct gpio_desc		*dsa1_gpios[5];
+	struct gpio_desc		*dsa2_gpios[5];
+	u32				gain[2];
+};
+
+static int admfm2000_mode(struct iio_dev *indio_dev, u32 chan, u32 mode)
+{
+	struct admfm2000_state *st = iio_priv(indio_dev);
+	int i;
+
+	switch (mode) {
+	case ADMFM2000_MIXER_MODE:
+		for (i = 0; i < ADMFM2000_MODE_GPIOS; i++) {
+			gpiod_set_value_cansleep(st->sw1_ch[i], (chan == 0) ? 1 : 0);
+			gpiod_set_value_cansleep(st->sw2_ch[i], (chan == 0) ? 0 : 1);
+		}
+		return 0;
+	case ADMFM2000_DIRECT_IF_MODE:
+		for (i = 0; i < ADMFM2000_MODE_GPIOS; i++) {
+			gpiod_set_value_cansleep(st->sw1_ch[i], (chan == 0) ? 0 : 1);
+			gpiod_set_value_cansleep(st->sw2_ch[i], (chan == 0) ? 1 : 0);
+		}
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int admfm2000_attenuation(struct iio_dev *indio_dev, u32 chan, u32 value)
+{
+	struct admfm2000_state *st = iio_priv(indio_dev);
+	int i;
+
+	switch (chan) {
+	case 0:
+		for (i = 0; i < ADMFM2000_DSA_GPIOS; i++)
+			gpiod_set_value_cansleep(st->dsa1_gpios[i], value & (1 << i));
+		return 0;
+	case 1:
+		for (i = 0; i < ADMFM2000_DSA_GPIOS; i++)
+			gpiod_set_value_cansleep(st->dsa2_gpios[i], value & (1 << i));
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int admfm2000_read_raw(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan, int *val,
+			      int *val2, long mask)
+{
+	struct admfm2000_state *st = iio_priv(indio_dev);
+	int gain;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		mutex_lock(&st->lock);
+		gain = ~(st->gain[chan->channel]) * -1000;
+		*val = gain / 1000;
+		*val2 = (gain % 1000) * 1000;
+		mutex_unlock(&st->lock);
+
+		return IIO_VAL_INT_PLUS_MICRO_DB;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int admfm2000_write_raw(struct iio_dev *indio_dev,
+			       struct iio_chan_spec const *chan, int val,
+			       int val2, long mask)
+{
+	struct admfm2000_state *st = iio_priv(indio_dev);
+	int gain, ret;
+
+	if (val < 0)
+		gain = (val * 1000) - (val2 / 1000);
+	else
+		gain = (val * 1000) + (val2 / 1000);
+
+	if (gain > ADMFM2000_MAX_GAIN || gain < ADMFM2000_MIN_GAIN)
+		return -EINVAL;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		mutex_lock(&st->lock);
+		st->gain[chan->channel] = ~((abs(gain) / 1000) & 0x1F);
+
+		ret = admfm2000_attenuation(indio_dev, chan->channel,
+					    st->gain[chan->channel]);
+		mutex_unlock(&st->lock);
+		return ret;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int admfm2000_write_raw_get_fmt(struct iio_dev *indio_dev,
+				       struct iio_chan_spec const *chan,
+				       long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		return IIO_VAL_INT_PLUS_MICRO_DB;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info admfm2000_info = {
+	.read_raw = &admfm2000_read_raw,
+	.write_raw = &admfm2000_write_raw,
+	.write_raw_get_fmt = &admfm2000_write_raw_get_fmt,
+};
+
+#define ADMFM2000_CHAN(_channel) {					\
+	.type = IIO_VOLTAGE,						\
+	.output = 1,							\
+	.indexed = 1,							\
+	.channel = _channel,						\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),		\
+}
+
+static const struct iio_chan_spec admfm2000_channels[] = {
+	ADMFM2000_CHAN(0),
+	ADMFM2000_CHAN(1),
+};
+
+static int admfm2000_channel_config(struct admfm2000_state *st,
+				    struct iio_dev *indio_dev)
+{
+	struct platform_device *pdev = to_platform_device(indio_dev->dev.parent);
+	struct device *dev = &pdev->dev;
+	struct gpio_desc **dsa;
+	struct gpio_desc **sw;
+	int ret, i;
+	bool mode;
+	u32 reg;
+
+	device_for_each_child_node_scoped(dev, child) {
+		ret = fwnode_property_read_u32(child, "reg", &reg);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "Failed to get reg property\n");
+
+		if (reg >= indio_dev->num_channels)
+			return dev_err_probe(dev, -EINVAL, "reg bigger than: %d\n",
+					     indio_dev->num_channels);
+
+		if (fwnode_property_present(child, "adi,mixer-mode"))
+			mode = ADMFM2000_MIXER_MODE;
+		else
+			mode = ADMFM2000_DIRECT_IF_MODE;
+
+		switch (reg) {
+		case 0:
+			sw = st->sw1_ch;
+			dsa = st->dsa1_gpios;
+			break;
+		case 1:
+			sw = st->sw2_ch;
+			dsa = st->dsa2_gpios;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		for (i = 0; i < ADMFM2000_MODE_GPIOS; i++) {
+			sw[i] = devm_fwnode_gpiod_get_index(dev, child, "switch",
+							    i, GPIOD_OUT_LOW, NULL);
+			if (IS_ERR(sw[i]))
+				return dev_err_probe(dev, PTR_ERR(sw[i]),
+						     "Failed to get gpios\n");
+		}
+
+		for (i = 0; i < ADMFM2000_DSA_GPIOS; i++) {
+			dsa[i] = devm_fwnode_gpiod_get_index(dev, child,
+							     "attenuation", i,
+							     GPIOD_OUT_LOW, NULL);
+			if (IS_ERR(dsa[i]))
+				return dev_err_probe(dev, PTR_ERR(dsa[i]),
+						     "Failed to get gpios\n");
+		}
+
+		ret = admfm2000_mode(indio_dev, reg, mode);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int admfm2000_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct admfm2000_state *st;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+
+	indio_dev->name = "admfm2000";
+	indio_dev->num_channels = ARRAY_SIZE(admfm2000_channels);
+	indio_dev->channels = admfm2000_channels;
+	indio_dev->info = &admfm2000_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	st->gain[0] = ADMFM2000_DEFAULT_GAIN;
+	st->gain[1] = ADMFM2000_DEFAULT_GAIN;
+
+	mutex_init(&st->lock);
+
+	ret = admfm2000_channel_config(st, indio_dev);
+	if (ret)
+		return ret;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct of_device_id admfm2000_of_match[] = {
+	{ .compatible = "adi,admfm2000" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, admfm2000_of_match);
+
+static struct platform_driver admfm2000_driver = {
+	.driver = {
+		.name = "admfm2000",
+		.of_match_table = admfm2000_of_match,
+	},
+	.probe = admfm2000_probe,
+};
+module_platform_driver(admfm2000_driver);
+
+MODULE_AUTHOR("Kim Seer Paller <kimseer.paller@analog.com>");
+MODULE_DESCRIPTION("ADMFM2000 Dual Microwave Down Converter");
+MODULE_LICENSE("GPL");