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, 283 insertions, 0 deletions

diff --git a/drivers/hwmon/powerz.c b/drivers/hwmon/powerz.c
new file mode 100644
index 000000000..6e1359144
--- /dev/null
+++ b/drivers/hwmon/powerz.c
@@ -0,0 +1,283 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Copyright (C) 2023 Thomas Weißschuh <linux@weissschuh.net>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/hwmon.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+#include <linux/usb.h>
+
+#define DRIVER_NAME	"powerz"
+#define POWERZ_EP_CMD_OUT	0x01
+#define POWERZ_EP_DATA_IN	0x81
+
+struct powerz_sensor_data {
+	u8 _unknown_1[8];
+	__le32 V_bus;
+	__le32 I_bus;
+	__le32 V_bus_avg;
+	__le32 I_bus_avg;
+	u8 _unknown_2[8];
+	u8 temp[2];
+	__le16 V_cc1;
+	__le16 V_cc2;
+	__le16 V_dp;
+	__le16 V_dm;
+	__le16 V_dd;
+	u8 _unknown_3[4];
+} __packed;
+
+struct powerz_priv {
+	__dma_from_device_group_begin();
+	char transfer_buffer[64];
+	__dma_from_device_group_end();
+	struct mutex mutex;
+	struct completion completion;
+	struct urb *urb;
+	int status;
+};
+
+static const struct hwmon_channel_info *const powerz_info[] = {
+	HWMON_CHANNEL_INFO(in,
+			   HWMON_I_INPUT | HWMON_I_LABEL | HWMON_I_AVERAGE,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL),
+	HWMON_CHANNEL_INFO(curr,
+			   HWMON_C_INPUT | HWMON_C_LABEL | HWMON_C_AVERAGE),
+	    HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_LABEL),
+	NULL
+};
+
+static int powerz_read_string(struct device *dev, enum hwmon_sensor_types type,
+			      u32 attr, int channel, const char **str)
+{
+	if (type == hwmon_curr && attr == hwmon_curr_label) {
+		*str = "IBUS";
+	} else if (type == hwmon_in && attr == hwmon_in_label) {
+		if (channel == 0)
+			*str = "VBUS";
+		else if (channel == 1)
+			*str = "VCC1";
+		else if (channel == 2)
+			*str = "VCC2";
+		else if (channel == 3)
+			*str = "VDP";
+		else if (channel == 4)
+			*str = "VDM";
+		else if (channel == 5)
+			*str = "VDD";
+		else
+			return -EOPNOTSUPP;
+	} else if (type == hwmon_temp && attr == hwmon_temp_label) {
+		*str = "TEMP";
+	} else {
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static void powerz_usb_data_complete(struct urb *urb)
+{
+	struct powerz_priv *priv = urb->context;
+
+	complete(&priv->completion);
+}
+
+static void powerz_usb_cmd_complete(struct urb *urb)
+{
+	struct powerz_priv *priv = urb->context;
+
+	usb_fill_bulk_urb(urb, urb->dev,
+			  usb_rcvbulkpipe(urb->dev, POWERZ_EP_DATA_IN),
+			  priv->transfer_buffer, sizeof(priv->transfer_buffer),
+			  powerz_usb_data_complete, priv);
+
+	priv->status = usb_submit_urb(urb, GFP_ATOMIC);
+	if (priv->status)
+		complete(&priv->completion);
+}
+
+static int powerz_read_data(struct usb_device *udev, struct powerz_priv *priv)
+{
+	long rc;
+	int ret;
+
+	if (!priv->urb)
+		return -ENODEV;
+
+	priv->status = -ETIMEDOUT;
+	reinit_completion(&priv->completion);
+
+	priv->transfer_buffer[0] = 0x0c;
+	priv->transfer_buffer[1] = 0x00;
+	priv->transfer_buffer[2] = 0x02;
+	priv->transfer_buffer[3] = 0x00;
+
+	usb_fill_bulk_urb(priv->urb, udev,
+			  usb_sndbulkpipe(udev, POWERZ_EP_CMD_OUT),
+			  priv->transfer_buffer, 4, powerz_usb_cmd_complete,
+			  priv);
+	ret = usb_submit_urb(priv->urb, GFP_KERNEL);
+	if (ret)
+		return ret;
+
+	rc = wait_for_completion_interruptible_timeout(&priv->completion,
+						       msecs_to_jiffies(5));
+	if (rc < 0) {
+		usb_kill_urb(priv->urb);
+		return rc;
+	}
+
+	if (rc == 0) {
+		usb_kill_urb(priv->urb);
+		return -EIO;
+	}
+
+	if (priv->urb->actual_length < sizeof(struct powerz_sensor_data))
+		return -EIO;
+
+	return priv->status;
+}
+
+static int powerz_read(struct device *dev, enum hwmon_sensor_types type,
+		       u32 attr, int channel, long *val)
+{
+	struct usb_interface *intf = to_usb_interface(dev->parent);
+	struct usb_device *udev = interface_to_usbdev(intf);
+	struct powerz_priv *priv = usb_get_intfdata(intf);
+	struct powerz_sensor_data *data;
+	int ret;
+
+	if (!priv)
+		return -EIO;	/* disconnected */
+
+	mutex_lock(&priv->mutex);
+	ret = powerz_read_data(udev, priv);
+	if (ret)
+		goto out;
+
+	data = (struct powerz_sensor_data *)priv->transfer_buffer;
+
+	if (type == hwmon_curr) {
+		if (attr == hwmon_curr_input)
+			*val = ((s32)le32_to_cpu(data->I_bus)) / 1000;
+		else if (attr == hwmon_curr_average)
+			*val = ((s32)le32_to_cpu(data->I_bus_avg)) / 1000;
+		else
+			ret = -EOPNOTSUPP;
+	} else if (type == hwmon_in) {
+		if (attr == hwmon_in_input) {
+			if (channel == 0)
+				*val = le32_to_cpu(data->V_bus) / 1000;
+			else if (channel == 1)
+				*val = le16_to_cpu(data->V_cc1) / 10;
+			else if (channel == 2)
+				*val = le16_to_cpu(data->V_cc2) / 10;
+			else if (channel == 3)
+				*val = le16_to_cpu(data->V_dp) / 10;
+			else if (channel == 4)
+				*val = le16_to_cpu(data->V_dm) / 10;
+			else if (channel == 5)
+				*val = le16_to_cpu(data->V_dd) / 10;
+			else
+				ret = -EOPNOTSUPP;
+		} else if (attr == hwmon_in_average && channel == 0) {
+			*val = le32_to_cpu(data->V_bus_avg) / 1000;
+		} else {
+			ret = -EOPNOTSUPP;
+		}
+	} else if (type == hwmon_temp && attr == hwmon_temp_input) {
+		*val = data->temp[1] * 2000 + data->temp[0] * 1000 / 128;
+	} else {
+		ret = -EOPNOTSUPP;
+	}
+
+out:
+	mutex_unlock(&priv->mutex);
+	return ret;
+}
+
+static const struct hwmon_ops powerz_hwmon_ops = {
+	.visible = 0444,
+	.read = powerz_read,
+	.read_string = powerz_read_string,
+};
+
+static const struct hwmon_chip_info powerz_chip_info = {
+	.ops = &powerz_hwmon_ops,
+	.info = powerz_info,
+};
+
+static int powerz_probe(struct usb_interface *intf,
+			const struct usb_device_id *id)
+{
+	struct powerz_priv *priv;
+	struct device *hwmon_dev;
+	struct device *parent;
+
+	parent = &intf->dev;
+
+	priv = devm_kzalloc(parent, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!priv->urb)
+		return -ENOMEM;
+	mutex_init(&priv->mutex);
+	init_completion(&priv->completion);
+
+	usb_set_intfdata(intf, priv);
+
+	hwmon_dev =
+	    devm_hwmon_device_register_with_info(parent, DRIVER_NAME, priv,
+						 &powerz_chip_info, NULL);
+	if (IS_ERR(hwmon_dev)) {
+		usb_free_urb(priv->urb);
+		return PTR_ERR(hwmon_dev);
+	}
+
+	return 0;
+}
+
+static void powerz_disconnect(struct usb_interface *intf)
+{
+	struct powerz_priv *priv = usb_get_intfdata(intf);
+
+	mutex_lock(&priv->mutex);
+	usb_kill_urb(priv->urb);
+	usb_free_urb(priv->urb);
+	priv->urb = NULL;
+	mutex_unlock(&priv->mutex);
+}
+
+static const struct usb_device_id powerz_id_table[] = {
+	{ USB_DEVICE_INTERFACE_NUMBER(0x5FC9, 0x0061, 0x00) },	/* ChargerLAB POWER-Z KM002C */
+	{ USB_DEVICE_INTERFACE_NUMBER(0x5FC9, 0x0063, 0x00) },	/* ChargerLAB POWER-Z KM003C */
+	{ }
+};
+
+MODULE_DEVICE_TABLE(usb, powerz_id_table);
+
+static struct usb_driver powerz_driver = {
+	.name = DRIVER_NAME,
+	.id_table = powerz_id_table,
+	.probe = powerz_probe,
+	.disconnect = powerz_disconnect,
+};
+
+module_usb_driver(powerz_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Thomas Weißschuh <linux@weissschuh.net>");
+MODULE_DESCRIPTION("ChargerLAB POWER-Z USB-C tester");