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, 281 insertions, 0 deletions

diff --git a/drivers/leds/leds-ns2.c b/drivers/leds/leds-ns2.c
new file mode 100644
index 000000000..4c6f04a5b
--- /dev/null
+++ b/drivers/leds/leds-ns2.c
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * leds-ns2.c - Driver for the Network Space v2 (and parents) dual-GPIO LED
+ *
+ * Copyright (C) 2010 LaCie
+ *
+ * Author: Simon Guinot <sguinot@lacie.com>
+ *
+ * Based on leds-gpio.c by Raphael Assenat <raph@8d.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/gpio/consumer.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include "leds.h"
+
+enum ns2_led_modes {
+	NS_V2_LED_OFF,
+	NS_V2_LED_ON,
+	NS_V2_LED_SATA,
+};
+
+/*
+ * If the size of this structure or types of its members is changed,
+ * the filling of array modval in function ns2_led_register must be changed
+ * accordingly.
+ */
+struct ns2_led_modval {
+	u32			mode;
+	u32			cmd_level;
+	u32			slow_level;
+} __packed;
+
+/*
+ * The Network Space v2 dual-GPIO LED is wired to a CPLD. Three different LED
+ * modes are available: off, on and SATA activity blinking. The LED modes are
+ * controlled through two GPIOs (command and slow): each combination of values
+ * for the command/slow GPIOs corresponds to a LED mode.
+ */
+
+struct ns2_led {
+	struct led_classdev	cdev;
+	struct gpio_desc	*cmd;
+	struct gpio_desc	*slow;
+	bool			can_sleep;
+	unsigned char		sata; /* True when SATA mode active. */
+	rwlock_t		rw_lock; /* Lock GPIOs. */
+	int			num_modes;
+	struct ns2_led_modval	*modval;
+};
+
+static int ns2_led_get_mode(struct ns2_led *led, enum ns2_led_modes *mode)
+{
+	int i;
+	int cmd_level;
+	int slow_level;
+
+	cmd_level = gpiod_get_value_cansleep(led->cmd);
+	slow_level = gpiod_get_value_cansleep(led->slow);
+
+	for (i = 0; i < led->num_modes; i++) {
+		if (cmd_level == led->modval[i].cmd_level &&
+		    slow_level == led->modval[i].slow_level) {
+			*mode = led->modval[i].mode;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static void ns2_led_set_mode(struct ns2_led *led, enum ns2_led_modes mode)
+{
+	int i;
+	unsigned long flags;
+
+	for (i = 0; i < led->num_modes; i++)
+		if (mode == led->modval[i].mode)
+			break;
+
+	if (i == led->num_modes)
+		return;
+
+	write_lock_irqsave(&led->rw_lock, flags);
+
+	if (!led->can_sleep) {
+		gpiod_set_value(led->cmd, led->modval[i].cmd_level);
+		gpiod_set_value(led->slow, led->modval[i].slow_level);
+		goto exit_unlock;
+	}
+
+	gpiod_set_value_cansleep(led->cmd, led->modval[i].cmd_level);
+	gpiod_set_value_cansleep(led->slow, led->modval[i].slow_level);
+
+exit_unlock:
+	write_unlock_irqrestore(&led->rw_lock, flags);
+}
+
+static void ns2_led_set(struct led_classdev *led_cdev,
+			enum led_brightness value)
+{
+	struct ns2_led *led = container_of(led_cdev, struct ns2_led, cdev);
+	enum ns2_led_modes mode;
+
+	if (value == LED_OFF)
+		mode = NS_V2_LED_OFF;
+	else if (led->sata)
+		mode = NS_V2_LED_SATA;
+	else
+		mode = NS_V2_LED_ON;
+
+	ns2_led_set_mode(led, mode);
+}
+
+static int ns2_led_set_blocking(struct led_classdev *led_cdev,
+			enum led_brightness value)
+{
+	ns2_led_set(led_cdev, value);
+	return 0;
+}
+
+static ssize_t ns2_led_sata_store(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buff, size_t count)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct ns2_led *led = container_of(led_cdev, struct ns2_led, cdev);
+	int ret;
+	unsigned long enable;
+
+	ret = kstrtoul(buff, 10, &enable);
+	if (ret < 0)
+		return ret;
+
+	enable = !!enable;
+
+	if (led->sata == enable)
+		goto exit;
+
+	led->sata = enable;
+
+	if (!led_get_brightness(led_cdev))
+		goto exit;
+
+	if (enable)
+		ns2_led_set_mode(led, NS_V2_LED_SATA);
+	else
+		ns2_led_set_mode(led, NS_V2_LED_ON);
+
+exit:
+	return count;
+}
+
+static ssize_t ns2_led_sata_show(struct device *dev,
+				 struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct ns2_led *led = container_of(led_cdev, struct ns2_led, cdev);
+
+	return sprintf(buf, "%d\n", led->sata);
+}
+
+static DEVICE_ATTR(sata, 0644, ns2_led_sata_show, ns2_led_sata_store);
+
+static struct attribute *ns2_led_attrs[] = {
+	&dev_attr_sata.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(ns2_led);
+
+static int ns2_led_register(struct device *dev, struct fwnode_handle *node,
+			    struct ns2_led *led)
+{
+	struct led_init_data init_data = {};
+	struct ns2_led_modval *modval;
+	enum ns2_led_modes mode;
+	int nmodes, ret;
+
+	led->cmd = devm_fwnode_gpiod_get_index(dev, node, "cmd", 0, GPIOD_ASIS,
+					       fwnode_get_name(node));
+	if (IS_ERR(led->cmd))
+		return PTR_ERR(led->cmd);
+
+	led->slow = devm_fwnode_gpiod_get_index(dev, node, "slow", 0,
+						GPIOD_ASIS,
+						fwnode_get_name(node));
+	if (IS_ERR(led->slow))
+		return PTR_ERR(led->slow);
+
+	ret = fwnode_property_count_u32(node, "modes-map");
+	if (ret < 0 || ret % 3) {
+		dev_err(dev, "Missing or malformed modes-map for %pfw\n", node);
+		return -EINVAL;
+	}
+
+	nmodes = ret / 3;
+	modval = devm_kcalloc(dev, nmodes, sizeof(*modval), GFP_KERNEL);
+	if (!modval)
+		return -ENOMEM;
+
+	fwnode_property_read_u32_array(node, "modes-map", (void *)modval,
+				       nmodes * 3);
+
+	rwlock_init(&led->rw_lock);
+
+	led->cdev.blink_set = NULL;
+	led->cdev.flags |= LED_CORE_SUSPENDRESUME;
+	led->cdev.groups = ns2_led_groups;
+	led->can_sleep = gpiod_cansleep(led->cmd) || gpiod_cansleep(led->slow);
+	if (led->can_sleep)
+		led->cdev.brightness_set_blocking = ns2_led_set_blocking;
+	else
+		led->cdev.brightness_set = ns2_led_set;
+	led->num_modes = nmodes;
+	led->modval = modval;
+
+	ret = ns2_led_get_mode(led, &mode);
+	if (ret < 0)
+		return ret;
+
+	/* Set LED initial state. */
+	led->sata = (mode == NS_V2_LED_SATA) ? 1 : 0;
+	led->cdev.brightness = (mode == NS_V2_LED_OFF) ? LED_OFF : LED_FULL;
+
+	init_data.fwnode = node;
+
+	ret = devm_led_classdev_register_ext(dev, &led->cdev, &init_data);
+	if (ret)
+		dev_err(dev, "Failed to register LED for node %pfw\n", node);
+
+	return ret;
+}
+
+static int ns2_led_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct ns2_led *leds;
+	int count;
+	int ret;
+
+	count = device_get_child_node_count(dev);
+	if (!count)
+		return -ENODEV;
+
+	leds = devm_kcalloc(dev, count, sizeof(*leds), GFP_KERNEL);
+	if (!leds)
+		return -ENOMEM;
+
+	device_for_each_child_node_scoped(dev, child) {
+		ret = ns2_led_register(dev, child, leds++);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id of_ns2_leds_match[] = {
+	{ .compatible = "lacie,ns2-leds", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, of_ns2_leds_match);
+
+static struct platform_driver ns2_led_driver = {
+	.probe		= ns2_led_probe,
+	.driver		= {
+		.name		= "leds-ns2",
+		.of_match_table	= of_ns2_leds_match,
+	},
+};
+
+module_platform_driver(ns2_led_driver);
+
+MODULE_AUTHOR("Simon Guinot <sguinot@lacie.com>");
+MODULE_DESCRIPTION("Network Space v2 LED driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:leds-ns2");