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, 239 insertions, 0 deletions

diff --git a/drivers/video/backlight/locomolcd.c b/drivers/video/backlight/locomolcd.c
new file mode 100644
index 000000000..1b493fb05
--- /dev/null
+++ b/drivers/video/backlight/locomolcd.c
@@ -0,0 +1,239 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Backlight control code for Sharp Zaurus SL-5500
+ *
+ * Copyright 2005 John Lenz <lenz@cs.wisc.edu>
+ * Maintainer: Pavel Machek <pavel@ucw.cz> (unless John wants to :-)
+ *
+ * This driver assumes single CPU. That's okay, because collie is
+ * slightly old hardware, and no one is going to retrofit second CPU to
+ * old PDA.
+ */
+
+/* LCD power functions */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/backlight.h>
+
+#include <asm/hardware/locomo.h>
+#include <asm/irq.h>
+#include <asm/mach/sharpsl_param.h>
+#include <asm/mach-types.h>
+
+#include "../../../arch/arm/mach-sa1100/generic.h"
+
+static struct backlight_device *locomolcd_bl_device;
+static struct locomo_dev *locomolcd_dev;
+static unsigned long locomolcd_flags;
+#define LOCOMOLCD_SUSPENDED     0x01
+
+static void locomolcd_on(int comadj)
+{
+	locomo_gpio_set_dir(locomolcd_dev->dev.parent, LOCOMO_GPIO_LCD_VSHA_ON, 0);
+	locomo_gpio_write(locomolcd_dev->dev.parent, LOCOMO_GPIO_LCD_VSHA_ON, 1);
+	mdelay(2);
+
+	locomo_gpio_set_dir(locomolcd_dev->dev.parent, LOCOMO_GPIO_LCD_VSHD_ON, 0);
+	locomo_gpio_write(locomolcd_dev->dev.parent, LOCOMO_GPIO_LCD_VSHD_ON, 1);
+	mdelay(2);
+
+	locomo_m62332_senddata(locomolcd_dev, comadj, 0);
+	mdelay(5);
+
+	locomo_gpio_set_dir(locomolcd_dev->dev.parent, LOCOMO_GPIO_LCD_VEE_ON, 0);
+	locomo_gpio_write(locomolcd_dev->dev.parent, LOCOMO_GPIO_LCD_VEE_ON, 1);
+	mdelay(10);
+
+	/* TFTCRST | CPSOUT=0 | CPSEN */
+	locomo_writel(0x01, locomolcd_dev->mapbase + LOCOMO_TC);
+
+	/* Set CPSD */
+	locomo_writel(6, locomolcd_dev->mapbase + LOCOMO_CPSD);
+
+	/* TFTCRST | CPSOUT=0 | CPSEN */
+	locomo_writel((0x04 | 0x01), locomolcd_dev->mapbase + LOCOMO_TC);
+	mdelay(10);
+
+	locomo_gpio_set_dir(locomolcd_dev->dev.parent, LOCOMO_GPIO_LCD_MOD, 0);
+	locomo_gpio_write(locomolcd_dev->dev.parent, LOCOMO_GPIO_LCD_MOD, 1);
+}
+
+static void locomolcd_off(int comadj)
+{
+	/* TFTCRST=1 | CPSOUT=1 | CPSEN = 0 */
+	locomo_writel(0x06, locomolcd_dev->mapbase + LOCOMO_TC);
+	mdelay(1);
+
+	locomo_gpio_write(locomolcd_dev->dev.parent, LOCOMO_GPIO_LCD_VSHA_ON, 0);
+	mdelay(110);
+
+	locomo_gpio_write(locomolcd_dev->dev.parent, LOCOMO_GPIO_LCD_VEE_ON, 0);
+	mdelay(700);
+
+	/* TFTCRST=0 | CPSOUT=0 | CPSEN = 0 */
+	locomo_writel(0, locomolcd_dev->mapbase + LOCOMO_TC);
+	locomo_gpio_write(locomolcd_dev->dev.parent, LOCOMO_GPIO_LCD_MOD, 0);
+	locomo_gpio_write(locomolcd_dev->dev.parent, LOCOMO_GPIO_LCD_VSHD_ON, 0);
+}
+
+void locomolcd_power(int on)
+{
+	int comadj = sharpsl_param.comadj;
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	if (!locomolcd_dev) {
+		local_irq_restore(flags);
+		return;
+	}
+
+	/* read comadj */
+	if (comadj == -1 && machine_is_collie())
+		comadj = 128;
+
+	if (on)
+		locomolcd_on(comadj);
+	else
+		locomolcd_off(comadj);
+
+	local_irq_restore(flags);
+}
+EXPORT_SYMBOL(locomolcd_power);
+
+static int current_intensity;
+
+static int locomolcd_set_intensity(struct backlight_device *bd)
+{
+	int intensity = backlight_get_brightness(bd);
+
+	if (locomolcd_flags & LOCOMOLCD_SUSPENDED)
+		intensity = 0;
+
+	switch (intensity) {
+	/*
+	 * AC and non-AC are handled differently,
+	 * but produce same results in sharp code?
+	 */
+	case 0:
+		locomo_frontlight_set(locomolcd_dev, 0, 0, 161);
+		break;
+	case 1:
+		locomo_frontlight_set(locomolcd_dev, 117, 0, 161);
+		break;
+	case 2:
+		locomo_frontlight_set(locomolcd_dev, 163, 0, 148);
+		break;
+	case 3:
+		locomo_frontlight_set(locomolcd_dev, 194, 0, 161);
+		break;
+	case 4:
+		locomo_frontlight_set(locomolcd_dev, 194, 1, 161);
+		break;
+	default:
+		return -ENODEV;
+	}
+	current_intensity = intensity;
+	return 0;
+}
+
+static int locomolcd_get_intensity(struct backlight_device *bd)
+{
+	return current_intensity;
+}
+
+static const struct backlight_ops locomobl_data = {
+	.get_brightness = locomolcd_get_intensity,
+	.update_status  = locomolcd_set_intensity,
+};
+
+#ifdef CONFIG_PM_SLEEP
+static int locomolcd_suspend(struct device *dev)
+{
+	locomolcd_flags |= LOCOMOLCD_SUSPENDED;
+	locomolcd_set_intensity(locomolcd_bl_device);
+	return 0;
+}
+
+static int locomolcd_resume(struct device *dev)
+{
+	locomolcd_flags &= ~LOCOMOLCD_SUSPENDED;
+	locomolcd_set_intensity(locomolcd_bl_device);
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(locomolcd_pm_ops, locomolcd_suspend, locomolcd_resume);
+
+static int locomolcd_probe(struct locomo_dev *ldev)
+{
+	struct backlight_properties props;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	locomolcd_dev = ldev;
+
+	locomo_gpio_set_dir(ldev->dev.parent, LOCOMO_GPIO_FL_VR, 0);
+
+	local_irq_restore(flags);
+
+	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
+	props.max_brightness = 4;
+	locomolcd_bl_device = backlight_device_register("locomo-bl",
+							&ldev->dev, NULL,
+							&locomobl_data, &props);
+
+	if (IS_ERR(locomolcd_bl_device))
+		return PTR_ERR(locomolcd_bl_device);
+
+	/* Set up frontlight so that screen is readable */
+	locomolcd_bl_device->props.brightness = 2;
+	locomolcd_set_intensity(locomolcd_bl_device);
+
+	return 0;
+}
+
+static void locomolcd_remove(struct locomo_dev *dev)
+{
+	unsigned long flags;
+
+	locomolcd_bl_device->props.brightness = 0;
+	locomolcd_bl_device->props.power = 0;
+	locomolcd_set_intensity(locomolcd_bl_device);
+
+	backlight_device_unregister(locomolcd_bl_device);
+	local_irq_save(flags);
+	locomolcd_dev = NULL;
+	local_irq_restore(flags);
+}
+
+static struct locomo_driver poodle_lcd_driver = {
+	.drv = {
+		.name	= "locomo-backlight",
+		.pm	= &locomolcd_pm_ops,
+	},
+	.devid	= LOCOMO_DEVID_BACKLIGHT,
+	.probe	= locomolcd_probe,
+	.remove	= locomolcd_remove,
+};
+
+static int __init locomolcd_init(void)
+{
+	return locomo_driver_register(&poodle_lcd_driver);
+}
+
+static void __exit locomolcd_exit(void)
+{
+	locomo_driver_unregister(&poodle_lcd_driver);
+}
+
+module_init(locomolcd_init);
+module_exit(locomolcd_exit);
+
+MODULE_AUTHOR("John Lenz <lenz@cs.wisc.edu>, Pavel Machek <pavel@ucw.cz>");
+MODULE_DESCRIPTION("Collie LCD driver");
+MODULE_LICENSE("GPL");