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, 129 insertions, 0 deletions

diff --git a/drivers/input/misc/max77650-onkey.c b/drivers/input/misc/max77650-onkey.c
new file mode 100644
index 000000000..ee55f22db
--- /dev/null
+++ b/drivers/input/misc/max77650-onkey.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (C) 2018 BayLibre SAS
+// Author: Bartosz Golaszewski <bgolaszewski@baylibre.com>
+//
+// ONKEY driver for MAXIM 77650/77651 charger/power-supply.
+
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/max77650.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define MAX77650_ONKEY_MODE_MASK	BIT(3)
+#define MAX77650_ONKEY_MODE_PUSH	0x00
+#define MAX77650_ONKEY_MODE_SLIDE	BIT(3)
+
+struct max77650_onkey {
+	struct input_dev *input;
+	unsigned int code;
+};
+
+static irqreturn_t max77650_onkey_falling(int irq, void *data)
+{
+	struct max77650_onkey *onkey = data;
+
+	input_report_key(onkey->input, onkey->code, 0);
+	input_sync(onkey->input);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t max77650_onkey_rising(int irq, void *data)
+{
+	struct max77650_onkey *onkey = data;
+
+	input_report_key(onkey->input, onkey->code, 1);
+	input_sync(onkey->input);
+
+	return IRQ_HANDLED;
+}
+
+static int max77650_onkey_probe(struct platform_device *pdev)
+{
+	int irq_r, irq_f, error, mode;
+	struct max77650_onkey *onkey;
+	struct device *dev, *parent;
+	struct regmap *map;
+	unsigned int type;
+
+	dev = &pdev->dev;
+	parent = dev->parent;
+
+	map = dev_get_regmap(parent, NULL);
+	if (!map)
+		return -ENODEV;
+
+	onkey = devm_kzalloc(dev, sizeof(*onkey), GFP_KERNEL);
+	if (!onkey)
+		return -ENOMEM;
+
+	error = device_property_read_u32(dev, "linux,code", &onkey->code);
+	if (error)
+		onkey->code = KEY_POWER;
+
+	if (device_property_read_bool(dev, "maxim,onkey-slide")) {
+		mode = MAX77650_ONKEY_MODE_SLIDE;
+		type = EV_SW;
+	} else {
+		mode = MAX77650_ONKEY_MODE_PUSH;
+		type = EV_KEY;
+	}
+
+	error = regmap_update_bits(map, MAX77650_REG_CNFG_GLBL,
+				   MAX77650_ONKEY_MODE_MASK, mode);
+	if (error)
+		return error;
+
+	irq_f = platform_get_irq_byname(pdev, "nEN_F");
+	if (irq_f < 0)
+		return irq_f;
+
+	irq_r = platform_get_irq_byname(pdev, "nEN_R");
+	if (irq_r < 0)
+		return irq_r;
+
+	onkey->input = devm_input_allocate_device(dev);
+	if (!onkey->input)
+		return -ENOMEM;
+
+	onkey->input->name = "max77650_onkey";
+	onkey->input->phys = "max77650_onkey/input0";
+	onkey->input->id.bustype = BUS_I2C;
+	input_set_capability(onkey->input, type, onkey->code);
+
+	error = devm_request_any_context_irq(dev, irq_f, max77650_onkey_falling,
+					     IRQF_ONESHOT, "onkey-down", onkey);
+	if (error < 0)
+		return error;
+
+	error = devm_request_any_context_irq(dev, irq_r, max77650_onkey_rising,
+					     IRQF_ONESHOT, "onkey-up", onkey);
+	if (error < 0)
+		return error;
+
+	return input_register_device(onkey->input);
+}
+
+static const struct of_device_id max77650_onkey_of_match[] = {
+	{ .compatible = "maxim,max77650-onkey" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max77650_onkey_of_match);
+
+static struct platform_driver max77650_onkey_driver = {
+	.driver = {
+		.name = "max77650-onkey",
+		.of_match_table = max77650_onkey_of_match,
+	},
+	.probe = max77650_onkey_probe,
+};
+module_platform_driver(max77650_onkey_driver);
+
+MODULE_DESCRIPTION("MAXIM 77650/77651 ONKEY driver");
+MODULE_AUTHOR("Bartosz Golaszewski <bgolaszewski@baylibre.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:max77650-onkey");