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, 142 insertions, 0 deletions

diff --git a/drivers/leds/leds-max77650.c b/drivers/leds/leds-max77650.c
new file mode 100644
index 000000000..f8c47078a
--- /dev/null
+++ b/drivers/leds/leds-max77650.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (C) 2018 BayLibre SAS
+// Author: Bartosz Golaszewski <bgolaszewski@baylibre.com>
+//
+// LED driver for MAXIM 77650/77651 charger/power-supply.
+
+#include <linux/i2c.h>
+#include <linux/leds.h>
+#include <linux/mfd/max77650.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define MAX77650_LED_NUM_LEDS		3
+
+#define MAX77650_LED_A_BASE		0x40
+#define MAX77650_LED_B_BASE		0x43
+
+#define MAX77650_LED_BR_MASK		GENMASK(4, 0)
+#define MAX77650_LED_EN_MASK		GENMASK(7, 6)
+
+#define MAX77650_LED_MAX_BRIGHTNESS	MAX77650_LED_BR_MASK
+
+/* Enable EN_LED_MSTR. */
+#define MAX77650_LED_TOP_DEFAULT	BIT(0)
+
+#define MAX77650_LED_ENABLE		GENMASK(7, 6)
+#define MAX77650_LED_DISABLE		0x00
+
+#define MAX77650_LED_A_DEFAULT		MAX77650_LED_DISABLE
+/* 100% on duty */
+#define MAX77650_LED_B_DEFAULT		GENMASK(3, 0)
+
+struct max77650_led {
+	struct led_classdev cdev;
+	struct regmap *map;
+	unsigned int regA;
+	unsigned int regB;
+};
+
+static struct max77650_led *max77650_to_led(struct led_classdev *cdev)
+{
+	return container_of(cdev, struct max77650_led, cdev);
+}
+
+static int max77650_led_brightness_set(struct led_classdev *cdev,
+				       enum led_brightness brightness)
+{
+	struct max77650_led *led = max77650_to_led(cdev);
+	int val, mask;
+
+	mask = MAX77650_LED_BR_MASK | MAX77650_LED_EN_MASK;
+
+	if (brightness == LED_OFF)
+		val = MAX77650_LED_DISABLE;
+	else
+		val = MAX77650_LED_ENABLE | brightness;
+
+	return regmap_update_bits(led->map, led->regA, mask, val);
+}
+
+static int max77650_led_probe(struct platform_device *pdev)
+{
+	struct max77650_led *leds, *led;
+	struct device *dev;
+	struct regmap *map;
+	int rv, num_leds;
+	u32 reg;
+
+	dev = &pdev->dev;
+
+	leds = devm_kcalloc(dev, sizeof(*leds),
+			    MAX77650_LED_NUM_LEDS, GFP_KERNEL);
+	if (!leds)
+		return -ENOMEM;
+
+	map = dev_get_regmap(dev->parent, NULL);
+	if (!map)
+		return -ENODEV;
+
+	num_leds = device_get_child_node_count(dev);
+	if (!num_leds || num_leds > MAX77650_LED_NUM_LEDS)
+		return -ENODEV;
+
+	device_for_each_child_node_scoped(dev, child) {
+		struct led_init_data init_data = {};
+
+		rv = fwnode_property_read_u32(child, "reg", &reg);
+		if (rv || reg >= MAX77650_LED_NUM_LEDS)
+			return -EINVAL;
+
+		led = &leds[reg];
+		led->map = map;
+		led->regA = MAX77650_LED_A_BASE + reg;
+		led->regB = MAX77650_LED_B_BASE + reg;
+		led->cdev.brightness_set_blocking = max77650_led_brightness_set;
+		led->cdev.max_brightness = MAX77650_LED_MAX_BRIGHTNESS;
+
+		init_data.fwnode = child;
+		init_data.devicename = "max77650";
+		/* for backwards compatibility if `label` is not present */
+		init_data.default_label = ":";
+
+		rv = devm_led_classdev_register_ext(dev, &led->cdev,
+						    &init_data);
+		if (rv)
+			return rv;
+
+		rv = regmap_write(map, led->regA, MAX77650_LED_A_DEFAULT);
+		if (rv)
+			return rv;
+
+		rv = regmap_write(map, led->regB, MAX77650_LED_B_DEFAULT);
+		if (rv)
+			return rv;
+	}
+
+	return regmap_write(map,
+			    MAX77650_REG_CNFG_LED_TOP,
+			    MAX77650_LED_TOP_DEFAULT);
+}
+
+static const struct of_device_id max77650_led_of_match[] = {
+	{ .compatible = "maxim,max77650-led" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max77650_led_of_match);
+
+static struct platform_driver max77650_led_driver = {
+	.driver = {
+		.name = "max77650-led",
+		.of_match_table = max77650_led_of_match,
+	},
+	.probe = max77650_led_probe,
+};
+module_platform_driver(max77650_led_driver);
+
+MODULE_DESCRIPTION("MAXIM 77650/77651 LED driver");
+MODULE_AUTHOR("Bartosz Golaszewski <bgolaszewski@baylibre.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:max77650-led");