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, 281 insertions, 0 deletions

diff --git a/drivers/nvme/host/hwmon.c b/drivers/nvme/host/hwmon.c
new file mode 100644
index 000000000..406203d8b
--- /dev/null
+++ b/drivers/nvme/host/hwmon.c
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * NVM Express hardware monitoring support
+ * Copyright (c) 2019, Guenter Roeck
+ */
+
+#include <linux/hwmon.h>
+#include <linux/units.h>
+#include <linux/unaligned.h>
+
+#include "nvme.h"
+
+struct nvme_hwmon_data {
+	struct nvme_ctrl *ctrl;
+	struct nvme_smart_log *log;
+	struct mutex read_lock;
+};
+
+static int nvme_get_temp_thresh(struct nvme_ctrl *ctrl, int sensor, bool under,
+				long *temp)
+{
+	unsigned int threshold = sensor << NVME_TEMP_THRESH_SELECT_SHIFT;
+	u32 status;
+	int ret;
+
+	if (under)
+		threshold |= NVME_TEMP_THRESH_TYPE_UNDER;
+
+	ret = nvme_get_features(ctrl, NVME_FEAT_TEMP_THRESH, threshold, NULL, 0,
+				&status);
+	if (ret > 0)
+		return -EIO;
+	if (ret < 0)
+		return ret;
+	*temp = kelvin_to_millicelsius(status & NVME_TEMP_THRESH_MASK);
+
+	return 0;
+}
+
+static int nvme_set_temp_thresh(struct nvme_ctrl *ctrl, int sensor, bool under,
+				long temp)
+{
+	unsigned int threshold = sensor << NVME_TEMP_THRESH_SELECT_SHIFT;
+	int ret;
+
+	temp = millicelsius_to_kelvin(temp);
+	threshold |= clamp_val(temp, 0, NVME_TEMP_THRESH_MASK);
+
+	if (under)
+		threshold |= NVME_TEMP_THRESH_TYPE_UNDER;
+
+	ret = nvme_set_features(ctrl, NVME_FEAT_TEMP_THRESH, threshold, NULL, 0,
+				NULL);
+	if (ret > 0)
+		return -EIO;
+
+	return ret;
+}
+
+static int nvme_hwmon_get_smart_log(struct nvme_hwmon_data *data)
+{
+	return nvme_get_log(data->ctrl, NVME_NSID_ALL, NVME_LOG_SMART, 0,
+			   NVME_CSI_NVM, data->log, sizeof(*data->log), 0);
+}
+
+static int nvme_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
+			   u32 attr, int channel, long *val)
+{
+	struct nvme_hwmon_data *data = dev_get_drvdata(dev);
+	struct nvme_smart_log *log = data->log;
+	int temp;
+	int err;
+
+	/*
+	 * First handle attributes which don't require us to read
+	 * the smart log.
+	 */
+	switch (attr) {
+	case hwmon_temp_max:
+		return nvme_get_temp_thresh(data->ctrl, channel, false, val);
+	case hwmon_temp_min:
+		return nvme_get_temp_thresh(data->ctrl, channel, true, val);
+	case hwmon_temp_crit:
+		*val = kelvin_to_millicelsius(data->ctrl->cctemp);
+		return 0;
+	default:
+		break;
+	}
+
+	mutex_lock(&data->read_lock);
+	err = nvme_hwmon_get_smart_log(data);
+	if (err)
+		goto unlock;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		if (!channel)
+			temp = get_unaligned_le16(log->temperature);
+		else
+			temp = le16_to_cpu(log->temp_sensor[channel - 1]);
+		*val = kelvin_to_millicelsius(temp);
+		break;
+	case hwmon_temp_alarm:
+		*val = !!(log->critical_warning & NVME_SMART_CRIT_TEMPERATURE);
+		break;
+	default:
+		err = -EOPNOTSUPP;
+		break;
+	}
+unlock:
+	mutex_unlock(&data->read_lock);
+	return err;
+}
+
+static int nvme_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
+			    u32 attr, int channel, long val)
+{
+	struct nvme_hwmon_data *data = dev_get_drvdata(dev);
+
+	switch (attr) {
+	case hwmon_temp_max:
+		return nvme_set_temp_thresh(data->ctrl, channel, false, val);
+	case hwmon_temp_min:
+		return nvme_set_temp_thresh(data->ctrl, channel, true, val);
+	default:
+		break;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static const char * const nvme_hwmon_sensor_names[] = {
+	"Composite",
+	"Sensor 1",
+	"Sensor 2",
+	"Sensor 3",
+	"Sensor 4",
+	"Sensor 5",
+	"Sensor 6",
+	"Sensor 7",
+	"Sensor 8",
+};
+
+static int nvme_hwmon_read_string(struct device *dev,
+				  enum hwmon_sensor_types type, u32 attr,
+				  int channel, const char **str)
+{
+	*str = nvme_hwmon_sensor_names[channel];
+	return 0;
+}
+
+static umode_t nvme_hwmon_is_visible(const void *_data,
+				     enum hwmon_sensor_types type,
+				     u32 attr, int channel)
+{
+	const struct nvme_hwmon_data *data = _data;
+
+	switch (attr) {
+	case hwmon_temp_crit:
+		if (!channel && data->ctrl->cctemp)
+			return 0444;
+		break;
+	case hwmon_temp_max:
+	case hwmon_temp_min:
+		if ((!channel && data->ctrl->wctemp) ||
+		    (channel && data->log->temp_sensor[channel - 1] &&
+		     !(data->ctrl->quirks &
+		       NVME_QUIRK_NO_SECONDARY_TEMP_THRESH))) {
+			if (data->ctrl->quirks &
+			    NVME_QUIRK_NO_TEMP_THRESH_CHANGE)
+				return 0444;
+			return 0644;
+		}
+		break;
+	case hwmon_temp_alarm:
+		if (!channel)
+			return 0444;
+		break;
+	case hwmon_temp_input:
+	case hwmon_temp_label:
+		if (!channel || data->log->temp_sensor[channel - 1])
+			return 0444;
+		break;
+	default:
+		break;
+	}
+	return 0;
+}
+
+static const struct hwmon_channel_info *const nvme_hwmon_info[] = {
+	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp,
+			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MIN |
+				HWMON_T_CRIT | HWMON_T_LABEL | HWMON_T_ALARM,
+			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MIN |
+				HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MIN |
+				HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MIN |
+				HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MIN |
+				HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MIN |
+				HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MIN |
+				HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MIN |
+				HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MIN |
+				HWMON_T_LABEL),
+	NULL
+};
+
+static const struct hwmon_ops nvme_hwmon_ops = {
+	.is_visible	= nvme_hwmon_is_visible,
+	.read		= nvme_hwmon_read,
+	.read_string	= nvme_hwmon_read_string,
+	.write		= nvme_hwmon_write,
+};
+
+static const struct hwmon_chip_info nvme_hwmon_chip_info = {
+	.ops	= &nvme_hwmon_ops,
+	.info	= nvme_hwmon_info,
+};
+
+int nvme_hwmon_init(struct nvme_ctrl *ctrl)
+{
+	struct device *dev = ctrl->device;
+	struct nvme_hwmon_data *data;
+	struct device *hwmon;
+	int err;
+
+	data = kzalloc_obj(*data);
+	if (!data)
+		return -ENOMEM;
+
+	data->log = kzalloc_obj(*data->log);
+	if (!data->log) {
+		err = -ENOMEM;
+		goto err_free_data;
+	}
+
+	data->ctrl = ctrl;
+	mutex_init(&data->read_lock);
+
+	err = nvme_hwmon_get_smart_log(data);
+	if (err) {
+		dev_warn(dev, "Failed to read smart log (error %d)\n", err);
+		goto err_free_log;
+	}
+
+	hwmon = hwmon_device_register_with_info(dev, "nvme",
+						data, &nvme_hwmon_chip_info,
+						NULL);
+	if (IS_ERR(hwmon)) {
+		dev_warn(dev, "Failed to instantiate hwmon device\n");
+		err = PTR_ERR(hwmon);
+		goto err_free_log;
+	}
+	ctrl->hwmon_device = hwmon;
+	return 0;
+
+err_free_log:
+	kfree(data->log);
+err_free_data:
+	kfree(data);
+	return err;
+}
+
+void nvme_hwmon_exit(struct nvme_ctrl *ctrl)
+{
+	if (ctrl->hwmon_device) {
+		struct nvme_hwmon_data *data =
+			dev_get_drvdata(ctrl->hwmon_device);
+
+		hwmon_device_unregister(ctrl->hwmon_device);
+		ctrl->hwmon_device = NULL;
+		kfree(data->log);
+		kfree(data);
+	}
+}