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, 294 insertions, 0 deletions

diff --git a/drivers/leds/leds-max8997.c b/drivers/leds/leds-max8997.c
new file mode 100644
index 000000000..c8d7f55c9
--- /dev/null
+++ b/drivers/leds/leds-max8997.c
@@ -0,0 +1,294 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * leds-max8997.c - LED class driver for MAX8997 LEDs.
+ *
+ * Copyright (C) 2011 Samsung Electronics
+ * Donggeun Kim <dg77.kim@samsung.com>
+ */
+
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/leds.h>
+#include <linux/mfd/max8997.h>
+#include <linux/mfd/max8997-private.h>
+#include <linux/platform_device.h>
+
+#define MAX8997_LED_FLASH_SHIFT			3
+#define MAX8997_LED_FLASH_CUR_MASK		0xf8
+#define MAX8997_LED_MOVIE_SHIFT			4
+#define MAX8997_LED_MOVIE_CUR_MASK		0xf0
+
+#define MAX8997_LED_FLASH_MAX_BRIGHTNESS	0x1f
+#define MAX8997_LED_MOVIE_MAX_BRIGHTNESS	0xf
+#define MAX8997_LED_NONE_MAX_BRIGHTNESS		0
+
+#define MAX8997_LED0_FLASH_MASK			0x1
+#define MAX8997_LED0_FLASH_PIN_MASK		0x5
+#define MAX8997_LED0_MOVIE_MASK			0x8
+#define MAX8997_LED0_MOVIE_PIN_MASK		0x28
+
+#define MAX8997_LED1_FLASH_MASK			0x2
+#define MAX8997_LED1_FLASH_PIN_MASK		0x6
+#define MAX8997_LED1_MOVIE_MASK			0x10
+#define MAX8997_LED1_MOVIE_PIN_MASK		0x30
+
+#define MAX8997_LED_BOOST_ENABLE_MASK		(1 << 6)
+
+struct max8997_led {
+	struct max8997_dev *iodev;
+	struct led_classdev cdev;
+	bool enabled;
+	int id;
+	enum max8997_led_mode led_mode;
+	struct mutex mutex;
+};
+
+static void max8997_led_set_mode(struct max8997_led *led,
+			enum max8997_led_mode mode)
+{
+	int ret;
+	struct i2c_client *client = led->iodev->i2c;
+	u8 mask = 0, val;
+
+	switch (mode) {
+	case MAX8997_FLASH_MODE:
+		mask = MAX8997_LED1_FLASH_MASK | MAX8997_LED0_FLASH_MASK;
+		val = led->id ?
+		      MAX8997_LED1_FLASH_MASK : MAX8997_LED0_FLASH_MASK;
+		led->cdev.max_brightness = MAX8997_LED_FLASH_MAX_BRIGHTNESS;
+		break;
+	case MAX8997_MOVIE_MODE:
+		mask = MAX8997_LED1_MOVIE_MASK | MAX8997_LED0_MOVIE_MASK;
+		val = led->id ?
+		      MAX8997_LED1_MOVIE_MASK : MAX8997_LED0_MOVIE_MASK;
+		led->cdev.max_brightness = MAX8997_LED_MOVIE_MAX_BRIGHTNESS;
+		break;
+	case MAX8997_FLASH_PIN_CONTROL_MODE:
+		mask = MAX8997_LED1_FLASH_PIN_MASK |
+		       MAX8997_LED0_FLASH_PIN_MASK;
+		val = led->id ?
+		      MAX8997_LED1_FLASH_PIN_MASK : MAX8997_LED0_FLASH_PIN_MASK;
+		led->cdev.max_brightness = MAX8997_LED_FLASH_MAX_BRIGHTNESS;
+		break;
+	case MAX8997_MOVIE_PIN_CONTROL_MODE:
+		mask = MAX8997_LED1_MOVIE_PIN_MASK |
+		       MAX8997_LED0_MOVIE_PIN_MASK;
+		val = led->id ?
+		      MAX8997_LED1_MOVIE_PIN_MASK : MAX8997_LED0_MOVIE_PIN_MASK;
+		led->cdev.max_brightness = MAX8997_LED_MOVIE_MAX_BRIGHTNESS;
+		break;
+	default:
+		led->cdev.max_brightness = MAX8997_LED_NONE_MAX_BRIGHTNESS;
+		break;
+	}
+
+	if (mask) {
+		ret = max8997_update_reg(client, MAX8997_REG_LEN_CNTL, val,
+					 mask);
+		if (ret)
+			dev_err(led->iodev->dev,
+				"failed to update register(%d)\n", ret);
+	}
+
+	led->led_mode = mode;
+}
+
+static void max8997_led_enable(struct max8997_led *led, bool enable)
+{
+	int ret;
+	struct i2c_client *client = led->iodev->i2c;
+	u8 val = 0, mask = MAX8997_LED_BOOST_ENABLE_MASK;
+
+	if (led->enabled == enable)
+		return;
+
+	val = enable ? MAX8997_LED_BOOST_ENABLE_MASK : 0;
+
+	ret = max8997_update_reg(client, MAX8997_REG_BOOST_CNTL, val, mask);
+	if (ret)
+		dev_err(led->iodev->dev,
+			"failed to update register(%d)\n", ret);
+
+	led->enabled = enable;
+}
+
+static void max8997_led_set_current(struct max8997_led *led,
+				enum led_brightness value)
+{
+	int ret;
+	struct i2c_client *client = led->iodev->i2c;
+	u8 val = 0, mask = 0, reg = 0;
+
+	switch (led->led_mode) {
+	case MAX8997_FLASH_MODE:
+	case MAX8997_FLASH_PIN_CONTROL_MODE:
+		val = value << MAX8997_LED_FLASH_SHIFT;
+		mask = MAX8997_LED_FLASH_CUR_MASK;
+		reg = led->id ? MAX8997_REG_FLASH2_CUR : MAX8997_REG_FLASH1_CUR;
+		break;
+	case MAX8997_MOVIE_MODE:
+	case MAX8997_MOVIE_PIN_CONTROL_MODE:
+		val = value << MAX8997_LED_MOVIE_SHIFT;
+		mask = MAX8997_LED_MOVIE_CUR_MASK;
+		reg = MAX8997_REG_MOVIE_CUR;
+		break;
+	default:
+		break;
+	}
+
+	if (mask) {
+		ret = max8997_update_reg(client, reg, val, mask);
+		if (ret)
+			dev_err(led->iodev->dev,
+				"failed to update register(%d)\n", ret);
+	}
+}
+
+static void max8997_led_brightness_set(struct led_classdev *led_cdev,
+				enum led_brightness value)
+{
+	struct max8997_led *led =
+			container_of(led_cdev, struct max8997_led, cdev);
+
+	if (value) {
+		max8997_led_set_current(led, value);
+		max8997_led_enable(led, true);
+	} else {
+		max8997_led_set_current(led, value);
+		max8997_led_enable(led, false);
+	}
+}
+
+static ssize_t mode_show(struct device *dev,
+			 struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct max8997_led *led =
+			container_of(led_cdev, struct max8997_led, cdev);
+	ssize_t ret = 0;
+
+	mutex_lock(&led->mutex);
+
+	switch (led->led_mode) {
+	case MAX8997_FLASH_MODE:
+		ret += sprintf(buf, "FLASH\n");
+		break;
+	case MAX8997_MOVIE_MODE:
+		ret += sprintf(buf, "MOVIE\n");
+		break;
+	case MAX8997_FLASH_PIN_CONTROL_MODE:
+		ret += sprintf(buf, "FLASH_PIN_CONTROL\n");
+		break;
+	case MAX8997_MOVIE_PIN_CONTROL_MODE:
+		ret += sprintf(buf, "MOVIE_PIN_CONTROL\n");
+		break;
+	default:
+		ret += sprintf(buf, "NONE\n");
+		break;
+	}
+
+	mutex_unlock(&led->mutex);
+
+	return ret;
+}
+
+static ssize_t mode_store(struct device *dev,
+			  struct device_attribute *attr,
+			  const char *buf, size_t size)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct max8997_led *led =
+			container_of(led_cdev, struct max8997_led, cdev);
+	enum max8997_led_mode mode;
+
+	mutex_lock(&led->mutex);
+
+	if (!strncmp(buf, "FLASH_PIN_CONTROL", 17))
+		mode = MAX8997_FLASH_PIN_CONTROL_MODE;
+	else if (!strncmp(buf, "MOVIE_PIN_CONTROL", 17))
+		mode = MAX8997_MOVIE_PIN_CONTROL_MODE;
+	else if (!strncmp(buf, "FLASH", 5))
+		mode = MAX8997_FLASH_MODE;
+	else if (!strncmp(buf, "MOVIE", 5))
+		mode = MAX8997_MOVIE_MODE;
+	else
+		mode = MAX8997_NONE;
+
+	max8997_led_set_mode(led, mode);
+
+	mutex_unlock(&led->mutex);
+
+	return size;
+}
+
+static DEVICE_ATTR_RW(mode);
+
+static struct attribute *max8997_attrs[] = {
+	&dev_attr_mode.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(max8997);
+
+static int max8997_led_probe(struct platform_device *pdev)
+{
+	struct max8997_dev *iodev = dev_get_drvdata(pdev->dev.parent);
+	struct max8997_platform_data *pdata = dev_get_platdata(iodev->dev);
+	struct max8997_led *led;
+	char name[20];
+	int ret = 0;
+
+	led = devm_kzalloc(&pdev->dev, sizeof(*led), GFP_KERNEL);
+	if (led == NULL)
+		return -ENOMEM;
+
+	led->id = pdev->id;
+	snprintf(name, sizeof(name), "max8997-led%d", pdev->id);
+
+	led->cdev.name = name;
+	led->cdev.brightness_set = max8997_led_brightness_set;
+	led->cdev.flags |= LED_CORE_SUSPENDRESUME;
+	led->cdev.brightness = 0;
+	led->cdev.groups = max8997_groups;
+	led->iodev = iodev;
+
+	/* initialize mode and brightness according to platform_data */
+	if (pdata && pdata->led_pdata) {
+		u8 mode = 0, brightness = 0;
+
+		mode = pdata->led_pdata->mode[led->id];
+		brightness = pdata->led_pdata->brightness[led->id];
+
+		max8997_led_set_mode(led, mode);
+
+		if (brightness > led->cdev.max_brightness)
+			brightness = led->cdev.max_brightness;
+		max8997_led_set_current(led, brightness);
+		led->cdev.brightness = brightness;
+	} else {
+		max8997_led_set_mode(led, MAX8997_NONE);
+		max8997_led_set_current(led, 0);
+	}
+
+	mutex_init(&led->mutex);
+
+	ret = devm_led_classdev_register(&pdev->dev, &led->cdev);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static struct platform_driver max8997_led_driver = {
+	.driver = {
+		.name  = "max8997-led",
+	},
+	.probe  = max8997_led_probe,
+};
+
+module_platform_driver(max8997_led_driver);
+
+MODULE_AUTHOR("Donggeun Kim <dg77.kim@samsung.com>");
+MODULE_DESCRIPTION("MAX8997 LED driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:max8997-led");