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, 329 insertions, 0 deletions

diff --git a/drivers/iio/proximity/ping.c b/drivers/iio/proximity/ping.c
new file mode 100644
index 000000000..1e646b858
--- /dev/null
+++ b/drivers/iio/proximity/ping.c
@@ -0,0 +1,329 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * PING: ultrasonic sensor for distance measuring by using only one GPIOs
+ *
+ * Copyright (c) 2019 Andreas Klinger <ak@it-klinger.de>
+ *
+ * For details about the devices see:
+ * http://parallax.com/sites/default/files/downloads/28041-LaserPING-2m-Rangefinder-Guide.pdf
+ * http://parallax.com/sites/default/files/downloads/28015-PING-Documentation-v1.6.pdf
+ *
+ * the measurement cycle as timing diagram looks like:
+ *
+ * GPIO      ___              ________________________
+ * ping:  __/   \____________/                        \________________
+ *          ^   ^            ^                        ^
+ *          |<->|            interrupt                interrupt
+ *         udelay(5)         (ts_rising)              (ts_falling)
+ *                           |<---------------------->|
+ *                           .  pulse time measured   .
+ *                           .  --> one round trip of ultra sonic waves
+ * ultra                     .                        .
+ * sonic            _   _   _.                        .
+ * burst: _________/ \_/ \_/ \_________________________________________
+ *                                                    .
+ * ultra                                              .
+ * sonic                                     _   _   _.
+ * echo:  __________________________________/ \_/ \_/ \________________
+ */
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/sched.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+struct ping_cfg {
+	unsigned long	trigger_pulse_us;	/* length of trigger pulse */
+	int		laserping_error;	/* support error code in */
+						/*   pulse width of laser */
+						/*   ping sensors */
+	s64		timeout_ns;		/* timeout in ns */
+};
+
+struct ping_data {
+	struct device		*dev;
+	struct gpio_desc	*gpiod_ping;
+	struct mutex		lock;
+	int			irqnr;
+	ktime_t			ts_rising;
+	ktime_t			ts_falling;
+	struct completion	rising;
+	struct completion	falling;
+	const struct ping_cfg	*cfg;
+};
+
+static const struct ping_cfg pa_ping_cfg = {
+	.trigger_pulse_us	= 5,
+	.laserping_error	= 0,
+	.timeout_ns		= 18500000,	/* 3 meters */
+};
+
+static const struct ping_cfg pa_laser_ping_cfg = {
+	.trigger_pulse_us	= 5,
+	.laserping_error	= 1,
+	.timeout_ns		= 15500000,	/* 2 meters plus error codes */
+};
+
+static irqreturn_t ping_handle_irq(int irq, void *dev_id)
+{
+	struct iio_dev *indio_dev = dev_id;
+	struct ping_data *data = iio_priv(indio_dev);
+	ktime_t now = ktime_get();
+
+	if (gpiod_get_value(data->gpiod_ping)) {
+		data->ts_rising = now;
+		complete(&data->rising);
+	} else {
+		data->ts_falling = now;
+		complete(&data->falling);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int ping_read(struct iio_dev *indio_dev)
+{
+	struct ping_data *data = iio_priv(indio_dev);
+	int ret;
+	ktime_t ktime_dt;
+	s64 dt_ns;
+	u32 time_ns, distance_mm;
+	struct platform_device *pdev = to_platform_device(data->dev);
+
+	/*
+	 * just one read-echo-cycle can take place at a time
+	 * ==> lock against concurrent reading calls
+	 */
+	mutex_lock(&data->lock);
+
+	reinit_completion(&data->rising);
+	reinit_completion(&data->falling);
+
+	gpiod_set_value(data->gpiod_ping, 1);
+	udelay(data->cfg->trigger_pulse_us);
+	gpiod_set_value(data->gpiod_ping, 0);
+
+	ret = gpiod_direction_input(data->gpiod_ping);
+	if (ret < 0) {
+		mutex_unlock(&data->lock);
+		return ret;
+	}
+
+	data->irqnr = gpiod_to_irq(data->gpiod_ping);
+	if (data->irqnr < 0) {
+		dev_err(data->dev, "gpiod_to_irq: %d\n", data->irqnr);
+		mutex_unlock(&data->lock);
+		return data->irqnr;
+	}
+
+	ret = request_irq(data->irqnr, ping_handle_irq,
+				IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
+							pdev->name, indio_dev);
+	if (ret < 0) {
+		dev_err(data->dev, "request_irq: %d\n", ret);
+		mutex_unlock(&data->lock);
+		return ret;
+	}
+
+	/* it should not take more than 20 ms until echo is rising */
+	ret = wait_for_completion_killable_timeout(&data->rising, HZ/50);
+	if (ret < 0)
+		goto err_reset_direction;
+	else if (ret == 0) {
+		ret = -ETIMEDOUT;
+		goto err_reset_direction;
+	}
+
+	/* it cannot take more than 50 ms until echo is falling */
+	ret = wait_for_completion_killable_timeout(&data->falling, HZ/20);
+	if (ret < 0)
+		goto err_reset_direction;
+	else if (ret == 0) {
+		ret = -ETIMEDOUT;
+		goto err_reset_direction;
+	}
+
+	ktime_dt = ktime_sub(data->ts_falling, data->ts_rising);
+
+	free_irq(data->irqnr, indio_dev);
+
+	ret = gpiod_direction_output(data->gpiod_ping, GPIOD_OUT_LOW);
+	if (ret < 0) {
+		mutex_unlock(&data->lock);
+		return ret;
+	}
+
+	mutex_unlock(&data->lock);
+
+	dt_ns = ktime_to_ns(ktime_dt);
+	if (dt_ns > data->cfg->timeout_ns) {
+		dev_dbg(data->dev, "distance out of range: dt=%lldns\n",
+								dt_ns);
+		return -EIO;
+	}
+
+	time_ns = dt_ns;
+
+	/*
+	 * read error code of laser ping sensor and give users chance to
+	 * figure out error by using dynamic debugging
+	 */
+	if (data->cfg->laserping_error) {
+		if ((time_ns > 12500000) && (time_ns <= 13500000)) {
+			dev_dbg(data->dev, "target too close or to far\n");
+			return -EIO;
+		}
+		if ((time_ns > 13500000) && (time_ns <= 14500000)) {
+			dev_dbg(data->dev, "internal sensor error\n");
+			return -EIO;
+		}
+		if ((time_ns > 14500000) && (time_ns <= 15500000)) {
+			dev_dbg(data->dev, "internal sensor timeout\n");
+			return -EIO;
+		}
+	}
+
+	/*
+	 * the speed as function of the temperature is approximately:
+	 *
+	 * speed = 331,5 + 0,6 * Temp
+	 *   with Temp in °C
+	 *   and speed in m/s
+	 *
+	 * use 343,5 m/s as ultrasonic speed at 20 °C here in absence of the
+	 * temperature
+	 *
+	 * therefore:
+	 *             time     343,5     time * 232
+	 * distance = ------ * ------- = ------------
+	 *             10^6         2        1350800
+	 *   with time in ns
+	 *   and distance in mm (one way)
+	 *
+	 * because we limit to 3 meters the multiplication with 232 just
+	 * fits into 32 bit
+	 */
+	distance_mm = time_ns * 232 / 1350800;
+
+	return distance_mm;
+
+err_reset_direction:
+	free_irq(data->irqnr, indio_dev);
+	mutex_unlock(&data->lock);
+
+	if (gpiod_direction_output(data->gpiod_ping, GPIOD_OUT_LOW))
+		dev_dbg(data->dev, "error in gpiod_direction_output\n");
+	return ret;
+}
+
+static int ping_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *channel, int *val,
+			    int *val2, long info)
+{
+	int ret;
+
+	if (channel->type != IIO_DISTANCE)
+		return -EINVAL;
+
+	switch (info) {
+	case IIO_CHAN_INFO_RAW:
+		ret = ping_read(indio_dev);
+		if (ret < 0)
+			return ret;
+		*val = ret;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		/*
+		 * maximum resolution in datasheet is 1 mm
+		 * 1 LSB is 1 mm
+		 */
+		*val = 0;
+		*val2 = 1000;
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info ping_iio_info = {
+	.read_raw		= ping_read_raw,
+};
+
+static const struct iio_chan_spec ping_chan_spec[] = {
+	{
+		.type = IIO_DISTANCE,
+		.info_mask_separate =
+				BIT(IIO_CHAN_INFO_RAW) |
+				BIT(IIO_CHAN_INFO_SCALE),
+	},
+};
+
+static const struct of_device_id of_ping_match[] = {
+	{ .compatible = "parallax,ping", .data = &pa_ping_cfg },
+	{ .compatible = "parallax,laserping", .data = &pa_laser_ping_cfg },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, of_ping_match);
+
+static int ping_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct ping_data *data;
+	struct iio_dev *indio_dev;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(struct ping_data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	data->dev = dev;
+	data->cfg = device_get_match_data(dev);
+
+	mutex_init(&data->lock);
+	init_completion(&data->rising);
+	init_completion(&data->falling);
+
+	data->gpiod_ping = devm_gpiod_get(dev, "ping", GPIOD_OUT_LOW);
+	if (IS_ERR(data->gpiod_ping)) {
+		dev_err(dev, "failed to get ping-gpios: err=%ld\n",
+						PTR_ERR(data->gpiod_ping));
+		return PTR_ERR(data->gpiod_ping);
+	}
+
+	if (gpiod_cansleep(data->gpiod_ping)) {
+		dev_err(data->dev, "cansleep-GPIOs not supported\n");
+		return -ENODEV;
+	}
+
+	platform_set_drvdata(pdev, indio_dev);
+
+	indio_dev->name = "ping";
+	indio_dev->info = &ping_iio_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = ping_chan_spec;
+	indio_dev->num_channels = ARRAY_SIZE(ping_chan_spec);
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static struct platform_driver ping_driver = {
+	.probe		= ping_probe,
+	.driver		= {
+		.name		= "ping-gpio",
+		.of_match_table	= of_ping_match,
+	},
+};
+
+module_platform_driver(ping_driver);
+
+MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
+MODULE_DESCRIPTION("PING sensors for distance measuring using one GPIOs");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ping");