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/hwmon/ad7314.c b/drivers/hwmon/ad7314.c
new file mode 100644
index 000000000..59424103f
--- /dev/null
+++ b/drivers/hwmon/ad7314.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * AD7314 digital temperature sensor driver for AD7314, ADT7301 and ADT7302
+ *
+ * Copyright 2010 Analog Devices Inc.
+ *
+ * Conversion to hwmon from IIO done by Jonathan Cameron <jic23@cam.ac.uk>
+ */
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/spi/spi.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/bitops.h>
+
+/*
+ * AD7314 temperature masks
+ */
+#define AD7314_TEMP_MASK		0x7FE0
+#define AD7314_TEMP_SHIFT		5
+#define AD7314_LEADING_ZEROS_MASK	BIT(15)
+
+/*
+ * ADT7301 and ADT7302 temperature masks
+ */
+#define ADT7301_TEMP_MASK		0x3FFF
+#define ADT7301_LEADING_ZEROS_MASK	(BIT(15) | BIT(14))
+
+enum ad7314_variant {
+	adt7301,
+	adt7302,
+	ad7314,
+};
+
+struct ad7314_data {
+	struct spi_device	*spi_dev;
+	u16 rx ____cacheline_aligned;
+};
+
+static int ad7314_spi_read(struct ad7314_data *chip)
+{
+	int ret;
+
+	ret = spi_read(chip->spi_dev, (u8 *)&chip->rx, sizeof(chip->rx));
+	if (ret < 0) {
+		dev_err(&chip->spi_dev->dev, "SPI read error\n");
+		return ret;
+	}
+
+	return be16_to_cpu(chip->rx);
+}
+
+static ssize_t ad7314_temperature_show(struct device *dev,
+				       struct device_attribute *attr,
+				       char *buf)
+{
+	struct ad7314_data *chip = dev_get_drvdata(dev);
+	s16 data;
+	int ret;
+
+	ret = ad7314_spi_read(chip);
+	if (ret < 0)
+		return ret;
+	switch (spi_get_device_id(chip->spi_dev)->driver_data) {
+	case ad7314:
+		if (ret & AD7314_LEADING_ZEROS_MASK) {
+			/* Invalid read-out, leading zero part is missing */
+			return -EIO;
+		}
+		data = (ret & AD7314_TEMP_MASK) >> AD7314_TEMP_SHIFT;
+		data = sign_extend32(data, 9);
+
+		return sprintf(buf, "%d\n", 250 * data);
+	case adt7301:
+	case adt7302:
+		if (ret & ADT7301_LEADING_ZEROS_MASK) {
+			/* Invalid read-out, leading zero part is missing */
+			return -EIO;
+		}
+		/*
+		 * Documented as a 13 bit twos complement register
+		 * with a sign bit - which is a 14 bit 2's complement
+		 * register.  1lsb - 31.25 milli degrees centigrade
+		 */
+		data = ret & ADT7301_TEMP_MASK;
+		data = sign_extend32(data, 13);
+
+		return sprintf(buf, "%d\n",
+			       DIV_ROUND_CLOSEST(data * 3125, 100));
+	default:
+		return -EINVAL;
+	}
+}
+
+static SENSOR_DEVICE_ATTR_RO(temp1_input, ad7314_temperature, 0);
+
+static struct attribute *ad7314_attrs[] = {
+	&sensor_dev_attr_temp1_input.dev_attr.attr,
+	NULL,
+};
+
+ATTRIBUTE_GROUPS(ad7314);
+
+static int ad7314_probe(struct spi_device *spi_dev)
+{
+	struct ad7314_data *chip;
+	struct device *hwmon_dev;
+
+	chip = devm_kzalloc(&spi_dev->dev, sizeof(*chip), GFP_KERNEL);
+	if (chip == NULL)
+		return -ENOMEM;
+
+	chip->spi_dev = spi_dev;
+	hwmon_dev = devm_hwmon_device_register_with_groups(&spi_dev->dev,
+							   spi_dev->modalias,
+							   chip, ad7314_groups);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct spi_device_id ad7314_id[] = {
+	{ "adt7301", adt7301 },
+	{ "adt7302", adt7302 },
+	{ "ad7314", ad7314 },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, ad7314_id);
+
+static struct spi_driver ad7314_driver = {
+	.driver = {
+		.name = "ad7314",
+	},
+	.probe = ad7314_probe,
+	.id_table = ad7314_id,
+};
+
+module_spi_driver(ad7314_driver);
+
+MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD7314, ADT7301 and ADT7302 digital temperature sensor driver");
+MODULE_LICENSE("GPL v2");