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, 226 insertions, 0 deletions

diff --git a/drivers/leds/leds-cpcap.c b/drivers/leds/leds-cpcap.c
new file mode 100644
index 000000000..87354f176
--- /dev/null
+++ b/drivers/leds/leds-cpcap.c
@@ -0,0 +1,226 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2017 Sebastian Reichel <sre@kernel.org>
+ */
+
+#include <linux/leds.h>
+#include <linux/mfd/motorola-cpcap.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+
+#define CPCAP_LED_NO_CURRENT 0x0001
+
+struct cpcap_led_info {
+	u16 reg;
+	u16 mask;
+	u16 limit;
+	u16 init_mask;
+	u16 init_val;
+};
+
+static const struct cpcap_led_info cpcap_led_red = {
+	.reg	= CPCAP_REG_REDC,
+	.mask	= 0x03FF,
+	.limit	= 31,
+};
+
+static const struct cpcap_led_info cpcap_led_green = {
+	.reg	= CPCAP_REG_GREENC,
+	.mask	= 0x03FF,
+	.limit	= 31,
+};
+
+static const struct cpcap_led_info cpcap_led_blue = {
+	.reg	= CPCAP_REG_BLUEC,
+	.mask	= 0x03FF,
+	.limit	= 31,
+};
+
+/* aux display light */
+static const struct cpcap_led_info cpcap_led_adl = {
+	.reg		= CPCAP_REG_ADLC,
+	.mask		= 0x000F,
+	.limit		= 1,
+	.init_mask	= 0x7FFF,
+	.init_val	= 0x5FF0,
+};
+
+/* camera privacy led */
+static const struct cpcap_led_info cpcap_led_cp = {
+	.reg		= CPCAP_REG_CLEDC,
+	.mask		= 0x0007,
+	.limit		= 1,
+	.init_mask	= 0x03FF,
+	.init_val	= 0x0008,
+};
+
+struct cpcap_led {
+	struct led_classdev led;
+	const struct cpcap_led_info *info;
+	struct device *dev;
+	struct regmap *regmap;
+	struct mutex update_lock;
+	struct regulator *vdd;
+	bool powered;
+
+	u32 current_limit;
+};
+
+static u16 cpcap_led_val(u8 current_limit, u8 duty_cycle)
+{
+	current_limit &= 0x1f; /* 5 bit */
+	duty_cycle &= 0x0f; /* 4 bit */
+
+	return current_limit << 4 | duty_cycle;
+}
+
+static int cpcap_led_set_power(struct cpcap_led *led, bool status)
+{
+	int err;
+
+	if (status == led->powered)
+		return 0;
+
+	if (status)
+		err = regulator_enable(led->vdd);
+	else
+		err = regulator_disable(led->vdd);
+
+	if (err) {
+		dev_err(led->dev, "regulator failure: %d", err);
+		return err;
+	}
+
+	led->powered = status;
+
+	return 0;
+}
+
+static int cpcap_led_set(struct led_classdev *ledc, enum led_brightness value)
+{
+	struct cpcap_led *led = container_of(ledc, struct cpcap_led, led);
+	int brightness;
+	int err;
+
+	mutex_lock(&led->update_lock);
+
+	if (value > LED_OFF) {
+		err = cpcap_led_set_power(led, true);
+		if (err)
+			goto exit;
+	}
+
+	if (value == LED_OFF) {
+		/* Avoid HW issue by turning off current before duty cycle */
+		err = regmap_update_bits(led->regmap,
+			led->info->reg, led->info->mask, CPCAP_LED_NO_CURRENT);
+		if (err) {
+			dev_err(led->dev, "regmap failed: %d", err);
+			goto exit;
+		}
+
+		brightness = cpcap_led_val(value, LED_OFF);
+	} else {
+		brightness = cpcap_led_val(value, LED_ON);
+	}
+
+	err = regmap_update_bits(led->regmap, led->info->reg, led->info->mask,
+		brightness);
+	if (err) {
+		dev_err(led->dev, "regmap failed: %d", err);
+		goto exit;
+	}
+
+	if (value == LED_OFF) {
+		err = cpcap_led_set_power(led, false);
+		if (err)
+			goto exit;
+	}
+
+exit:
+	mutex_unlock(&led->update_lock);
+	return err;
+}
+
+static const struct of_device_id cpcap_led_of_match[] = {
+	{ .compatible = "motorola,cpcap-led-red", .data = &cpcap_led_red },
+	{ .compatible = "motorola,cpcap-led-green", .data = &cpcap_led_green },
+	{ .compatible = "motorola,cpcap-led-blue",  .data = &cpcap_led_blue },
+	{ .compatible = "motorola,cpcap-led-adl", .data = &cpcap_led_adl },
+	{ .compatible = "motorola,cpcap-led-cp", .data = &cpcap_led_cp },
+	{},
+};
+MODULE_DEVICE_TABLE(of, cpcap_led_of_match);
+
+static int cpcap_led_probe(struct platform_device *pdev)
+{
+	struct cpcap_led *led;
+	int err;
+
+	led = devm_kzalloc(&pdev->dev, sizeof(*led), GFP_KERNEL);
+	if (!led)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, led);
+	led->info = device_get_match_data(&pdev->dev);
+	led->dev = &pdev->dev;
+
+	if (led->info->reg == 0x0000) {
+		dev_err(led->dev, "Unsupported LED");
+		return -ENODEV;
+	}
+
+	led->regmap = dev_get_regmap(pdev->dev.parent, NULL);
+	if (!led->regmap)
+		return -ENODEV;
+
+	led->vdd = devm_regulator_get(&pdev->dev, "vdd");
+	if (IS_ERR(led->vdd)) {
+		err = PTR_ERR(led->vdd);
+		dev_err(led->dev, "Couldn't get regulator: %d", err);
+		return err;
+	}
+
+	err = device_property_read_string(&pdev->dev, "label", &led->led.name);
+	if (err) {
+		dev_err(led->dev, "Couldn't read LED label: %d", err);
+		return err;
+	}
+
+	if (led->info->init_mask) {
+		err = regmap_update_bits(led->regmap, led->info->reg,
+			led->info->init_mask, led->info->init_val);
+		if (err) {
+			dev_err(led->dev, "regmap failed: %d", err);
+			return err;
+		}
+	}
+
+	mutex_init(&led->update_lock);
+
+	led->led.max_brightness = led->info->limit;
+	led->led.brightness_set_blocking = cpcap_led_set;
+	err = devm_led_classdev_register(&pdev->dev, &led->led);
+	if (err) {
+		dev_err(led->dev, "Couldn't register LED: %d", err);
+		return err;
+	}
+
+	return 0;
+}
+
+static struct platform_driver cpcap_led_driver = {
+	.probe = cpcap_led_probe,
+	.driver = {
+		.name = "cpcap-led",
+		.of_match_table = cpcap_led_of_match,
+	},
+};
+module_platform_driver(cpcap_led_driver);
+
+MODULE_DESCRIPTION("CPCAP LED driver");
+MODULE_AUTHOR("Sebastian Reichel <sre@kernel.org>");
+MODULE_LICENSE("GPL");