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, 274 insertions, 0 deletions

diff --git a/drivers/input/misc/pwm-vibra.c b/drivers/input/misc/pwm-vibra.c
new file mode 100644
index 000000000..3e5ed685e
--- /dev/null
+++ b/drivers/input/misc/pwm-vibra.c
@@ -0,0 +1,274 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  PWM vibrator driver
+ *
+ *  Copyright (C) 2017 Collabora Ltd.
+ *
+ *  Based on previous work from:
+ *  Copyright (C) 2012 Dmitry Torokhov <dmitry.torokhov@gmail.com>
+ *
+ *  Based on PWM beeper driver:
+ *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/pwm.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+struct pwm_vibrator {
+	struct input_dev *input;
+	struct gpio_desc *enable_gpio;
+	struct pwm_device *pwm;
+	struct pwm_device *pwm_dir;
+	struct regulator *vcc;
+
+	struct work_struct play_work;
+	u16 level;
+	u32 direction_duty_cycle;
+	bool vcc_on;
+};
+
+static int pwm_vibrator_start(struct pwm_vibrator *vibrator)
+{
+	struct device *pdev = vibrator->input->dev.parent;
+	struct pwm_state state;
+	int err;
+
+	if (!vibrator->vcc_on) {
+		err = regulator_enable(vibrator->vcc);
+		if (err) {
+			dev_err(pdev, "failed to enable regulator: %d\n", err);
+			return err;
+		}
+		vibrator->vcc_on = true;
+	}
+
+	gpiod_set_value_cansleep(vibrator->enable_gpio, 1);
+
+	pwm_get_state(vibrator->pwm, &state);
+	pwm_set_relative_duty_cycle(&state, vibrator->level, 0xffff);
+	state.enabled = true;
+
+	err = pwm_apply_might_sleep(vibrator->pwm, &state);
+	if (err) {
+		dev_err(pdev, "failed to apply pwm state: %d\n", err);
+		return err;
+	}
+
+	if (vibrator->pwm_dir) {
+		pwm_get_state(vibrator->pwm_dir, &state);
+		state.duty_cycle = vibrator->direction_duty_cycle;
+		state.enabled = true;
+
+		err = pwm_apply_might_sleep(vibrator->pwm_dir, &state);
+		if (err) {
+			dev_err(pdev, "failed to apply dir-pwm state: %d\n", err);
+			pwm_disable(vibrator->pwm);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+static void pwm_vibrator_stop(struct pwm_vibrator *vibrator)
+{
+	if (vibrator->pwm_dir)
+		pwm_disable(vibrator->pwm_dir);
+	pwm_disable(vibrator->pwm);
+
+	gpiod_set_value_cansleep(vibrator->enable_gpio, 0);
+
+	if (vibrator->vcc_on) {
+		regulator_disable(vibrator->vcc);
+		vibrator->vcc_on = false;
+	}
+}
+
+static void pwm_vibrator_play_work(struct work_struct *work)
+{
+	struct pwm_vibrator *vibrator = container_of(work,
+					struct pwm_vibrator, play_work);
+
+	if (vibrator->level)
+		pwm_vibrator_start(vibrator);
+	else
+		pwm_vibrator_stop(vibrator);
+}
+
+static int pwm_vibrator_play_effect(struct input_dev *dev, void *data,
+				    struct ff_effect *effect)
+{
+	struct pwm_vibrator *vibrator = input_get_drvdata(dev);
+
+	vibrator->level = effect->u.rumble.strong_magnitude;
+	if (!vibrator->level)
+		vibrator->level = effect->u.rumble.weak_magnitude;
+
+	schedule_work(&vibrator->play_work);
+
+	return 0;
+}
+
+static void pwm_vibrator_close(struct input_dev *input)
+{
+	struct pwm_vibrator *vibrator = input_get_drvdata(input);
+
+	cancel_work_sync(&vibrator->play_work);
+	pwm_vibrator_stop(vibrator);
+}
+
+static int pwm_vibrator_probe(struct platform_device *pdev)
+{
+	struct pwm_vibrator *vibrator;
+	struct pwm_state state;
+	int err;
+
+	vibrator = devm_kzalloc(&pdev->dev, sizeof(*vibrator), GFP_KERNEL);
+	if (!vibrator)
+		return -ENOMEM;
+
+	vibrator->input = devm_input_allocate_device(&pdev->dev);
+	if (!vibrator->input)
+		return -ENOMEM;
+
+	vibrator->vcc = devm_regulator_get(&pdev->dev, "vcc");
+	if (IS_ERR(vibrator->vcc))
+		return dev_err_probe(&pdev->dev, PTR_ERR(vibrator->vcc),
+				     "Failed to request regulator\n");
+
+	vibrator->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
+							GPIOD_OUT_LOW);
+	if (IS_ERR(vibrator->enable_gpio))
+		return dev_err_probe(&pdev->dev, PTR_ERR(vibrator->enable_gpio),
+				     "Failed to request enable gpio\n");
+
+	vibrator->pwm = devm_pwm_get(&pdev->dev, "enable");
+	if (IS_ERR(vibrator->pwm))
+		return dev_err_probe(&pdev->dev, PTR_ERR(vibrator->pwm),
+				     "Failed to request main pwm\n");
+
+	INIT_WORK(&vibrator->play_work, pwm_vibrator_play_work);
+
+	/* Sync up PWM state and ensure it is off. */
+	pwm_init_state(vibrator->pwm, &state);
+	state.enabled = false;
+	err = pwm_apply_might_sleep(vibrator->pwm, &state);
+	if (err) {
+		dev_err(&pdev->dev, "failed to apply initial PWM state: %d\n",
+			err);
+		return err;
+	}
+
+	vibrator->pwm_dir = devm_pwm_get(&pdev->dev, "direction");
+	err = PTR_ERR_OR_ZERO(vibrator->pwm_dir);
+	switch (err) {
+	case 0:
+		/* Sync up PWM state and ensure it is off. */
+		pwm_init_state(vibrator->pwm_dir, &state);
+		state.enabled = false;
+		err = pwm_apply_might_sleep(vibrator->pwm_dir, &state);
+		if (err) {
+			dev_err(&pdev->dev, "failed to apply initial PWM state: %d\n",
+				err);
+			return err;
+		}
+
+		vibrator->direction_duty_cycle =
+			pwm_get_period(vibrator->pwm_dir) / 2;
+		device_property_read_u32(&pdev->dev, "direction-duty-cycle-ns",
+					 &vibrator->direction_duty_cycle);
+		break;
+
+	case -ENODATA:
+		/* Direction PWM is optional */
+		vibrator->pwm_dir = NULL;
+		break;
+
+	default:
+		dev_err(&pdev->dev, "Failed to request direction pwm: %d\n", err);
+		fallthrough;
+
+	case -EPROBE_DEFER:
+		return err;
+	}
+
+	vibrator->input->name = "pwm-vibrator";
+	vibrator->input->id.bustype = BUS_HOST;
+	vibrator->input->dev.parent = &pdev->dev;
+	vibrator->input->close = pwm_vibrator_close;
+
+	input_set_drvdata(vibrator->input, vibrator);
+	input_set_capability(vibrator->input, EV_FF, FF_RUMBLE);
+
+	err = input_ff_create_memless(vibrator->input, NULL,
+				      pwm_vibrator_play_effect);
+	if (err) {
+		dev_err(&pdev->dev, "Couldn't create FF dev: %d\n", err);
+		return err;
+	}
+
+	err = input_register_device(vibrator->input);
+	if (err) {
+		dev_err(&pdev->dev, "Couldn't register input dev: %d\n", err);
+		return err;
+	}
+
+	platform_set_drvdata(pdev, vibrator);
+
+	return 0;
+}
+
+static int pwm_vibrator_suspend(struct device *dev)
+{
+	struct pwm_vibrator *vibrator = dev_get_drvdata(dev);
+
+	cancel_work_sync(&vibrator->play_work);
+	if (vibrator->level)
+		pwm_vibrator_stop(vibrator);
+
+	return 0;
+}
+
+static int pwm_vibrator_resume(struct device *dev)
+{
+	struct pwm_vibrator *vibrator = dev_get_drvdata(dev);
+
+	if (vibrator->level)
+		pwm_vibrator_start(vibrator);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(pwm_vibrator_pm_ops,
+				pwm_vibrator_suspend, pwm_vibrator_resume);
+
+#ifdef CONFIG_OF
+static const struct of_device_id pwm_vibra_dt_match_table[] = {
+	{ .compatible = "pwm-vibrator" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, pwm_vibra_dt_match_table);
+#endif
+
+static struct platform_driver pwm_vibrator_driver = {
+	.probe	= pwm_vibrator_probe,
+	.driver	= {
+		.name	= "pwm-vibrator",
+		.pm	= pm_sleep_ptr(&pwm_vibrator_pm_ops),
+		.of_match_table = of_match_ptr(pwm_vibra_dt_match_table),
+	},
+};
+module_platform_driver(pwm_vibrator_driver);
+
+MODULE_AUTHOR("Sebastian Reichel <sre@kernel.org>");
+MODULE_DESCRIPTION("PWM vibrator driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:pwm-vibrator");