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, 119 insertions, 0 deletions

diff --git a/drivers/input/misc/rt5120-pwrkey.c b/drivers/input/misc/rt5120-pwrkey.c
new file mode 100644
index 000000000..2262f5057
--- /dev/null
+++ b/drivers/input/misc/rt5120-pwrkey.c
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022 Richtek Technology Corp.
+ * Author: ChiYuan Huang <cy_huang@richtek.com>
+ */
+
+#include <linux/bits.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define RT5120_REG_INTSTAT	0x1E
+#define RT5120_PWRKEYSTAT_MASK	BIT(7)
+
+struct rt5120_priv {
+	struct regmap *regmap;
+	struct input_dev *input;
+};
+
+static irqreturn_t rt5120_pwrkey_handler(int irq, void *devid)
+{
+	struct rt5120_priv *priv = devid;
+	unsigned int stat;
+	int error;
+
+	error = regmap_read(priv->regmap, RT5120_REG_INTSTAT, &stat);
+	if (error)
+		return IRQ_NONE;
+
+	input_report_key(priv->input, KEY_POWER,
+			 !(stat & RT5120_PWRKEYSTAT_MASK));
+	input_sync(priv->input);
+
+	return IRQ_HANDLED;
+}
+
+static int rt5120_pwrkey_probe(struct platform_device *pdev)
+{
+	struct rt5120_priv *priv;
+	struct device *dev = &pdev->dev;
+	int press_irq, release_irq;
+	int error;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->regmap = dev_get_regmap(dev->parent, NULL);
+	if (!priv->regmap) {
+		dev_err(dev, "Failed to init regmap\n");
+		return -ENODEV;
+	}
+
+	press_irq = platform_get_irq_byname(pdev, "pwrkey-press");
+	if (press_irq < 0)
+		return press_irq;
+
+	release_irq = platform_get_irq_byname(pdev, "pwrkey-release");
+	if (release_irq < 0)
+		return release_irq;
+
+	/* Make input device be device resource managed */
+	priv->input = devm_input_allocate_device(dev);
+	if (!priv->input)
+		return -ENOMEM;
+
+	priv->input->name = "rt5120_pwrkey";
+	priv->input->phys = "rt5120_pwrkey/input0";
+	priv->input->id.bustype = BUS_I2C;
+	input_set_capability(priv->input, EV_KEY, KEY_POWER);
+
+	error = input_register_device(priv->input);
+	if (error) {
+		dev_err(dev, "Failed to register input device: %d\n", error);
+		return error;
+	}
+
+	error = devm_request_threaded_irq(dev, press_irq,
+					  NULL, rt5120_pwrkey_handler,
+					  0, "pwrkey-press", priv);
+	if (error) {
+		dev_err(dev,
+			"Failed to register pwrkey press irq: %d\n", error);
+		return error;
+	}
+
+	error = devm_request_threaded_irq(dev, release_irq,
+					  NULL, rt5120_pwrkey_handler,
+					  0, "pwrkey-release", priv);
+	if (error) {
+		dev_err(dev,
+			"Failed to register pwrkey release irq: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id r5120_pwrkey_match_table[] = {
+	{ .compatible = "richtek,rt5120-pwrkey" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, r5120_pwrkey_match_table);
+
+static struct platform_driver rt5120_pwrkey_driver = {
+	.driver = {
+		.name = "rt5120-pwrkey",
+		.of_match_table = r5120_pwrkey_match_table,
+	},
+	.probe = rt5120_pwrkey_probe,
+};
+module_platform_driver(rt5120_pwrkey_driver);
+
+MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
+MODULE_DESCRIPTION("Richtek RT5120 power key driver");
+MODULE_LICENSE("GPL");