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, 165 insertions, 0 deletions

diff --git a/drivers/extcon/extcon-gpio.c b/drivers/extcon/extcon-gpio.c
new file mode 100644
index 000000000..4105df74f
--- /dev/null
+++ b/drivers/extcon/extcon-gpio.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * extcon_gpio.c - Single-state GPIO extcon driver based on extcon class
+ *
+ * Copyright (C) 2008 Google, Inc.
+ * Author: Mike Lockwood <lockwood@android.com>
+ *
+ * Modified by MyungJoo Ham <myungjoo.ham@samsung.com> to support extcon
+ * (originally switch class is supported)
+ */
+
+#include <linux/devm-helpers.h>
+#include <linux/extcon-provider.h>
+#include <linux/gpio/consumer.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+
+/**
+ * struct gpio_extcon_data - A simple GPIO-controlled extcon device state container.
+ * @edev:		Extcon device.
+ * @work:		Work fired by the interrupt.
+ * @debounce_jiffies:	Number of jiffies to wait for the GPIO to stabilize, from the debounce
+ *			value.
+ * @gpiod:		GPIO descriptor for this external connector.
+ * @extcon_id:		The unique id of specific external connector.
+ * @debounce:		Debounce time for GPIO IRQ in ms.
+ * @check_on_resume:	Boolean describing whether to check the state of gpio
+ *			while resuming from sleep.
+ */
+struct gpio_extcon_data {
+	struct extcon_dev *edev;
+	struct delayed_work work;
+	unsigned long debounce_jiffies;
+	struct gpio_desc *gpiod;
+	unsigned int extcon_id;
+	unsigned long debounce;
+	bool check_on_resume;
+};
+
+static void gpio_extcon_work(struct work_struct *work)
+{
+	int state;
+	struct gpio_extcon_data	*data =
+		container_of(to_delayed_work(work), struct gpio_extcon_data,
+			     work);
+
+	state = gpiod_get_value_cansleep(data->gpiod);
+	extcon_set_state_sync(data->edev, data->extcon_id, state);
+}
+
+static irqreturn_t gpio_irq_handler(int irq, void *dev_id)
+{
+	struct gpio_extcon_data *data = dev_id;
+
+	queue_delayed_work(system_power_efficient_wq, &data->work,
+			      data->debounce_jiffies);
+	return IRQ_HANDLED;
+}
+
+static int gpio_extcon_probe(struct platform_device *pdev)
+{
+	struct gpio_extcon_data *data;
+	struct device *dev = &pdev->dev;
+	unsigned long irq_flags;
+	int irq;
+	int ret;
+
+	data = devm_kzalloc(dev, sizeof(struct gpio_extcon_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	/*
+	 * FIXME: extcon_id represents the unique identifier of external
+	 * connectors such as EXTCON_USB, EXTCON_DISP_HDMI and so on. extcon_id
+	 * is necessary to register the extcon device. But, it's not yet
+	 * developed to get the extcon id from device-tree or others.
+	 * On later, it have to be solved.
+	 */
+	if (data->extcon_id > EXTCON_NONE)
+		return -EINVAL;
+
+	data->gpiod = devm_gpiod_get(dev, "extcon", GPIOD_IN);
+	if (IS_ERR(data->gpiod))
+		return PTR_ERR(data->gpiod);
+	irq = gpiod_to_irq(data->gpiod);
+	if (irq <= 0)
+		return irq;
+
+	/*
+	 * It is unlikely that this is an acknowledged interrupt that goes
+	 * away after handling, what we are looking for are falling edges
+	 * if the signal is active low, and rising edges if the signal is
+	 * active high.
+	 */
+	if (gpiod_is_active_low(data->gpiod))
+		irq_flags = IRQF_TRIGGER_FALLING;
+	else
+		irq_flags = IRQF_TRIGGER_RISING;
+
+	/* Allocate the memory of extcon devie and register extcon device */
+	data->edev = devm_extcon_dev_allocate(dev, &data->extcon_id);
+	if (IS_ERR(data->edev)) {
+		dev_err(dev, "failed to allocate extcon device\n");
+		return -ENOMEM;
+	}
+
+	ret = devm_extcon_dev_register(dev, data->edev);
+	if (ret < 0)
+		return ret;
+
+	ret = devm_delayed_work_autocancel(dev, &data->work, gpio_extcon_work);
+	if (ret)
+		return ret;
+
+	/*
+	 * Request the interrupt of gpio to detect whether external connector
+	 * is attached or detached.
+	 */
+	ret = devm_request_any_context_irq(dev, irq,
+					gpio_irq_handler, irq_flags,
+					pdev->name, data);
+	if (ret < 0)
+		return ret;
+
+	platform_set_drvdata(pdev, data);
+	/* Perform initial detection */
+	gpio_extcon_work(&data->work.work);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int gpio_extcon_resume(struct device *dev)
+{
+	struct gpio_extcon_data *data;
+
+	data = dev_get_drvdata(dev);
+	if (data->check_on_resume)
+		queue_delayed_work(system_power_efficient_wq,
+			&data->work, data->debounce_jiffies);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(gpio_extcon_pm_ops, NULL, gpio_extcon_resume);
+
+static struct platform_driver gpio_extcon_driver = {
+	.probe		= gpio_extcon_probe,
+	.driver		= {
+		.name	= "extcon-gpio",
+		.pm	= &gpio_extcon_pm_ops,
+	},
+};
+
+module_platform_driver(gpio_extcon_driver);
+
+MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
+MODULE_DESCRIPTION("GPIO extcon driver");
+MODULE_LICENSE("GPL");