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, 126 insertions, 0 deletions

diff --git a/drivers/reset/reset-tps380x.c b/drivers/reset/reset-tps380x.c
new file mode 100644
index 000000000..09d511f06
--- /dev/null
+++ b/drivers/reset/reset-tps380x.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * TI TPS380x Supply Voltage Supervisor and Reset Controller Driver
+ *
+ * Copyright (C) 2022 Pengutronix, Marco Felsch <kernel@pengutronix.de>
+ *
+ * Based on Simple Reset Controller Driver
+ *
+ * Copyright (C) 2017 Pengutronix, Philipp Zabel <kernel@pengutronix.de>
+ */
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/reset-controller.h>
+
+struct tps380x_reset {
+	struct reset_controller_dev	rcdev;
+	struct gpio_desc		*reset_gpio;
+	unsigned int			reset_ms;
+};
+
+struct tps380x_reset_devdata {
+	unsigned int min_reset_ms;
+	unsigned int typ_reset_ms;
+	unsigned int max_reset_ms;
+};
+
+static inline
+struct tps380x_reset *to_tps380x_reset(struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct tps380x_reset, rcdev);
+}
+
+static int
+tps380x_reset_assert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct tps380x_reset *tps380x = to_tps380x_reset(rcdev);
+
+	gpiod_set_value_cansleep(tps380x->reset_gpio, 1);
+
+	return 0;
+}
+
+static int
+tps380x_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct tps380x_reset *tps380x = to_tps380x_reset(rcdev);
+
+	gpiod_set_value_cansleep(tps380x->reset_gpio, 0);
+	msleep(tps380x->reset_ms);
+
+	return 0;
+}
+
+static const struct reset_control_ops reset_tps380x_ops = {
+	.assert		= tps380x_reset_assert,
+	.deassert	= tps380x_reset_deassert,
+};
+
+static int tps380x_reset_of_xlate(struct reset_controller_dev *rcdev,
+				  const struct of_phandle_args *reset_spec)
+{
+	/* No special handling needed, we have only one reset line per device */
+	return 0;
+}
+
+static int tps380x_reset_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct tps380x_reset_devdata *devdata;
+	struct tps380x_reset *tps380x;
+
+	devdata = device_get_match_data(dev);
+	if (!devdata)
+		return -EINVAL;
+
+	tps380x = devm_kzalloc(dev, sizeof(*tps380x), GFP_KERNEL);
+	if (!tps380x)
+		return -ENOMEM;
+
+	tps380x->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(tps380x->reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(tps380x->reset_gpio),
+				     "Failed to get GPIO\n");
+
+	tps380x->reset_ms = devdata->max_reset_ms;
+
+	tps380x->rcdev.ops = &reset_tps380x_ops;
+	tps380x->rcdev.owner = THIS_MODULE;
+	tps380x->rcdev.dev = dev;
+	tps380x->rcdev.of_node = dev->of_node;
+	tps380x->rcdev.of_reset_n_cells = 0;
+	tps380x->rcdev.of_xlate = tps380x_reset_of_xlate;
+	tps380x->rcdev.nr_resets = 1;
+
+	return devm_reset_controller_register(dev, &tps380x->rcdev);
+}
+
+static const struct tps380x_reset_devdata tps3801_reset_data = {
+	.min_reset_ms = 120,
+	.typ_reset_ms = 200,
+	.max_reset_ms = 280,
+};
+
+static const struct of_device_id tps380x_reset_dt_ids[] = {
+	{ .compatible = "ti,tps3801", .data = &tps3801_reset_data },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, tps380x_reset_dt_ids);
+
+static struct platform_driver tps380x_reset_driver = {
+	.probe	= tps380x_reset_probe,
+	.driver = {
+		.name		= "tps380x-reset",
+		.of_match_table	= tps380x_reset_dt_ids,
+	},
+};
+module_platform_driver(tps380x_reset_driver);
+
+MODULE_AUTHOR("Marco Felsch <kernel@pengutronix.de>");
+MODULE_DESCRIPTION("TI TPS380x Supply Voltage Supervisor and Reset Driver");
+MODULE_LICENSE("GPL v2");