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, 225 insertions, 0 deletions

diff --git a/drivers/regulator/userspace-consumer.c b/drivers/regulator/userspace-consumer.c
new file mode 100644
index 000000000..72bb5ffb4
--- /dev/null
+++ b/drivers/regulator/userspace-consumer.c
@@ -0,0 +1,225 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * userspace-consumer.c
+ *
+ * Copyright 2009 CompuLab, Ltd.
+ *
+ * Author: Mike Rapoport <mike@compulab.co.il>
+ *
+ * Based of virtual consumer driver:
+ *   Copyright 2008 Wolfson Microelectronics PLC.
+ *   Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
+ */
+
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+#include <linux/regulator/userspace-consumer.h>
+#include <linux/slab.h>
+
+struct userspace_consumer_data {
+	const char *name;
+
+	struct mutex lock;
+	bool enabled;
+	bool no_autoswitch;
+
+	int num_supplies;
+	struct regulator_bulk_data *supplies;
+};
+
+static ssize_t name_show(struct device *dev,
+			 struct device_attribute *attr, char *buf)
+{
+	struct userspace_consumer_data *data = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%s\n", data->name);
+}
+
+static ssize_t state_show(struct device *dev,
+			  struct device_attribute *attr, char *buf)
+{
+	struct userspace_consumer_data *data = dev_get_drvdata(dev);
+
+	if (data->enabled)
+		return sprintf(buf, "enabled\n");
+
+	return sprintf(buf, "disabled\n");
+}
+
+static ssize_t state_store(struct device *dev, struct device_attribute *attr,
+			   const char *buf, size_t count)
+{
+	struct userspace_consumer_data *data = dev_get_drvdata(dev);
+	bool enabled;
+	int ret;
+
+	/*
+	 * sysfs_streq() doesn't need the \n's, but we add them so the strings
+	 * will be shared with show_state(), above.
+	 */
+	if (sysfs_streq(buf, "enabled\n") || sysfs_streq(buf, "1"))
+		enabled = true;
+	else if (sysfs_streq(buf, "disabled\n") || sysfs_streq(buf, "0"))
+		enabled = false;
+	else {
+		dev_err(dev, "Configuring invalid mode\n");
+		return count;
+	}
+
+	mutex_lock(&data->lock);
+	if (enabled != data->enabled) {
+		if (enabled)
+			ret = regulator_bulk_enable(data->num_supplies,
+						    data->supplies);
+		else
+			ret = regulator_bulk_disable(data->num_supplies,
+						     data->supplies);
+
+		if (ret == 0)
+			data->enabled = enabled;
+		else
+			dev_err(dev, "Failed to configure state: %d\n", ret);
+	}
+	mutex_unlock(&data->lock);
+
+	return count;
+}
+
+static DEVICE_ATTR_RO(name);
+static DEVICE_ATTR_RW(state);
+
+static struct attribute *attributes[] = {
+	&dev_attr_name.attr,
+	&dev_attr_state.attr,
+	NULL,
+};
+
+static umode_t attr_visible(struct kobject *kobj, struct attribute *attr, int idx)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct userspace_consumer_data *data = dev_get_drvdata(dev);
+
+	/* If a name hasn't been set, don't bother with the attribute */
+	if (attr == &dev_attr_name.attr && !data->name)
+		return 0;
+
+	return attr->mode;
+}
+
+static const struct attribute_group attr_group = {
+	.attrs	= attributes,
+	.is_visible =  attr_visible,
+};
+
+static int regulator_userspace_consumer_probe(struct platform_device *pdev)
+{
+	struct regulator_userspace_consumer_data tmpdata;
+	struct regulator_userspace_consumer_data *pdata;
+	struct userspace_consumer_data *drvdata;
+	int ret;
+
+	pdata = dev_get_platdata(&pdev->dev);
+	if (!pdata) {
+		if (!pdev->dev.of_node)
+			return -EINVAL;
+
+		pdata = &tmpdata;
+		memset(pdata, 0, sizeof(*pdata));
+
+		pdata->no_autoswitch = true;
+		pdata->num_supplies = 1;
+		pdata->supplies = devm_kzalloc(&pdev->dev, sizeof(*pdata->supplies), GFP_KERNEL);
+		if (!pdata->supplies)
+			return -ENOMEM;
+		pdata->supplies[0].supply = "vout";
+	}
+
+	if (pdata->num_supplies < 1) {
+		dev_err(&pdev->dev, "At least one supply required\n");
+		return -EINVAL;
+	}
+
+	drvdata = devm_kzalloc(&pdev->dev,
+			       sizeof(struct userspace_consumer_data),
+			       GFP_KERNEL);
+	if (drvdata == NULL)
+		return -ENOMEM;
+
+	drvdata->name = pdata->name;
+	drvdata->num_supplies = pdata->num_supplies;
+	drvdata->supplies = pdata->supplies;
+	drvdata->no_autoswitch = pdata->no_autoswitch;
+
+	mutex_init(&drvdata->lock);
+
+	ret = devm_regulator_bulk_get_exclusive(&pdev->dev, drvdata->num_supplies,
+						drvdata->supplies);
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret, "Failed to get supplies\n");
+
+	platform_set_drvdata(pdev, drvdata);
+
+	ret = sysfs_create_group(&pdev->dev.kobj, &attr_group);
+	if (ret != 0)
+		return ret;
+
+	if (pdata->init_on && !pdata->no_autoswitch) {
+		ret = regulator_bulk_enable(drvdata->num_supplies,
+					    drvdata->supplies);
+		if (ret) {
+			dev_err(&pdev->dev,
+				"Failed to set initial state: %d\n", ret);
+			goto err_enable;
+		}
+	}
+
+	ret = regulator_is_enabled(pdata->supplies[0].consumer);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to get regulator status\n");
+		goto err_enable;
+	}
+	drvdata->enabled = !!ret;
+
+	return 0;
+
+err_enable:
+	sysfs_remove_group(&pdev->dev.kobj, &attr_group);
+
+	return ret;
+}
+
+static void regulator_userspace_consumer_remove(struct platform_device *pdev)
+{
+	struct userspace_consumer_data *data = platform_get_drvdata(pdev);
+
+	sysfs_remove_group(&pdev->dev.kobj, &attr_group);
+
+	if (data->enabled && !data->no_autoswitch)
+		regulator_bulk_disable(data->num_supplies, data->supplies);
+}
+
+static const struct of_device_id regulator_userspace_consumer_of_match[] = {
+	{ .compatible = "regulator-output", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, regulator_userspace_consumer_of_match);
+
+static struct platform_driver regulator_userspace_consumer_driver = {
+	.probe		= regulator_userspace_consumer_probe,
+	.remove		= regulator_userspace_consumer_remove,
+	.driver		= {
+		.name		= "reg-userspace-consumer",
+		.probe_type	= PROBE_PREFER_ASYNCHRONOUS,
+		.of_match_table	= regulator_userspace_consumer_of_match,
+	},
+};
+
+module_platform_driver(regulator_userspace_consumer_driver);
+
+MODULE_AUTHOR("Mike Rapoport <mike@compulab.co.il>");
+MODULE_DESCRIPTION("Userspace consumer for voltage and current regulators");
+MODULE_LICENSE("GPL");