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, 130 insertions, 0 deletions

diff --git a/drivers/leds/leds-wrap.c b/drivers/leds/leds-wrap.c
new file mode 100644
index 000000000..794697e16
--- /dev/null
+++ b/drivers/leds/leds-wrap.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * LEDs driver for PCEngines WRAP
+ *
+ * Copyright (C) 2006 Kristian Kielhofner <kris@krisk.org>
+ *
+ * Based on leds-net48xx.c
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/leds.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/scx200_gpio.h>
+#include <linux/module.h>
+
+#define DRVNAME "wrap-led"
+#define WRAP_POWER_LED_GPIO	2
+#define WRAP_ERROR_LED_GPIO	3
+#define WRAP_EXTRA_LED_GPIO	18
+
+static struct platform_device *pdev;
+
+static void wrap_power_led_set(struct led_classdev *led_cdev,
+		enum led_brightness value)
+{
+	if (value)
+		scx200_gpio_set_low(WRAP_POWER_LED_GPIO);
+	else
+		scx200_gpio_set_high(WRAP_POWER_LED_GPIO);
+}
+
+static void wrap_error_led_set(struct led_classdev *led_cdev,
+		enum led_brightness value)
+{
+	if (value)
+		scx200_gpio_set_low(WRAP_ERROR_LED_GPIO);
+	else
+		scx200_gpio_set_high(WRAP_ERROR_LED_GPIO);
+}
+
+static void wrap_extra_led_set(struct led_classdev *led_cdev,
+		enum led_brightness value)
+{
+	if (value)
+		scx200_gpio_set_low(WRAP_EXTRA_LED_GPIO);
+	else
+		scx200_gpio_set_high(WRAP_EXTRA_LED_GPIO);
+}
+
+static struct led_classdev wrap_power_led = {
+	.name			= "wrap::power",
+	.brightness_set		= wrap_power_led_set,
+	.default_trigger	= "default-on",
+	.flags			= LED_CORE_SUSPENDRESUME,
+};
+
+static struct led_classdev wrap_error_led = {
+	.name		= "wrap::error",
+	.brightness_set	= wrap_error_led_set,
+	.flags			= LED_CORE_SUSPENDRESUME,
+};
+
+static struct led_classdev wrap_extra_led = {
+	.name           = "wrap::extra",
+	.brightness_set = wrap_extra_led_set,
+	.flags			= LED_CORE_SUSPENDRESUME,
+};
+
+static int wrap_led_probe(struct platform_device *pdev)
+{
+	int ret;
+
+	ret = devm_led_classdev_register(&pdev->dev, &wrap_power_led);
+	if (ret < 0)
+		return ret;
+
+	ret = devm_led_classdev_register(&pdev->dev, &wrap_error_led);
+	if (ret < 0)
+		return ret;
+
+	return  devm_led_classdev_register(&pdev->dev, &wrap_extra_led);
+}
+
+static struct platform_driver wrap_led_driver = {
+	.probe		= wrap_led_probe,
+	.driver		= {
+		.name		= DRVNAME,
+	},
+};
+
+static int __init wrap_led_init(void)
+{
+	int ret;
+
+	if (!scx200_gpio_present()) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	ret = platform_driver_register(&wrap_led_driver);
+	if (ret < 0)
+		goto out;
+
+	pdev = platform_device_register_simple(DRVNAME, -1, NULL, 0);
+	if (IS_ERR(pdev)) {
+		ret = PTR_ERR(pdev);
+		platform_driver_unregister(&wrap_led_driver);
+		goto out;
+	}
+
+out:
+	return ret;
+}
+
+static void __exit wrap_led_exit(void)
+{
+	platform_device_unregister(pdev);
+	platform_driver_unregister(&wrap_led_driver);
+}
+
+module_init(wrap_led_init);
+module_exit(wrap_led_exit);
+
+MODULE_AUTHOR("Kristian Kielhofner <kris@krisk.org>");
+MODULE_DESCRIPTION("PCEngines WRAP LED driver");
+MODULE_LICENSE("GPL");
+