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, 238 insertions, 0 deletions

diff --git a/drivers/input/keyboard/cypress-sf.c b/drivers/input/keyboard/cypress-sf.c
new file mode 100644
index 000000000..4b2ae07f3
--- /dev/null
+++ b/drivers/input/keyboard/cypress-sf.c
@@ -0,0 +1,238 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Cypress StreetFighter Touchkey Driver
+ *
+ * Copyright (c) 2021 Yassine Oudjana <y.oudjana@protonmail.com>
+ */
+
+#include <linux/bitmap.h>
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/pm.h>
+#include <linux/regulator/consumer.h>
+
+#define CYPRESS_SF_DEV_NAME "cypress-sf"
+
+#define CYPRESS_SF_REG_BUTTON_STATUS	0x4a
+
+struct cypress_sf_data {
+	struct i2c_client *client;
+	struct input_dev *input_dev;
+	struct regulator_bulk_data regulators[2];
+	u32 *keycodes;
+	unsigned long keystates;
+	int num_keys;
+};
+
+static irqreturn_t cypress_sf_irq_handler(int irq, void *devid)
+{
+	struct cypress_sf_data *touchkey = devid;
+	unsigned long keystates, changed;
+	bool new_state;
+	int val, key;
+
+	val = i2c_smbus_read_byte_data(touchkey->client,
+				       CYPRESS_SF_REG_BUTTON_STATUS);
+	if (val < 0) {
+		dev_err(&touchkey->client->dev,
+			"Failed to read button status: %d", val);
+		return IRQ_NONE;
+	}
+	keystates = val;
+
+	bitmap_xor(&changed, &keystates, &touchkey->keystates,
+		   touchkey->num_keys);
+
+	for_each_set_bit(key, &changed, touchkey->num_keys) {
+		new_state = keystates & BIT(key);
+		dev_dbg(&touchkey->client->dev,
+			"Key %d changed to %d", key, new_state);
+		input_report_key(touchkey->input_dev,
+				 touchkey->keycodes[key], new_state);
+	}
+
+	input_sync(touchkey->input_dev);
+	touchkey->keystates = keystates;
+
+	return IRQ_HANDLED;
+}
+
+static void cypress_sf_disable_regulators(void *arg)
+{
+	struct cypress_sf_data *touchkey = arg;
+
+	regulator_bulk_disable(ARRAY_SIZE(touchkey->regulators),
+			       touchkey->regulators);
+}
+
+static int cypress_sf_probe(struct i2c_client *client)
+{
+	struct cypress_sf_data *touchkey;
+	int key, error;
+
+	touchkey = devm_kzalloc(&client->dev, sizeof(*touchkey), GFP_KERNEL);
+	if (!touchkey)
+		return -ENOMEM;
+
+	touchkey->client = client;
+	i2c_set_clientdata(client, touchkey);
+
+	touchkey->regulators[0].supply = "vdd";
+	touchkey->regulators[1].supply = "avdd";
+
+	error = devm_regulator_bulk_get(&client->dev,
+					ARRAY_SIZE(touchkey->regulators),
+					touchkey->regulators);
+	if (error) {
+		dev_err(&client->dev, "Failed to get regulators: %d\n", error);
+		return error;
+	}
+
+	touchkey->num_keys = device_property_read_u32_array(&client->dev,
+							    "linux,keycodes",
+							    NULL, 0);
+	if (touchkey->num_keys < 0) {
+		/* Default key count */
+		touchkey->num_keys = 2;
+	}
+
+	touchkey->keycodes = devm_kcalloc(&client->dev,
+					  touchkey->num_keys,
+					  sizeof(*touchkey->keycodes),
+					  GFP_KERNEL);
+	if (!touchkey->keycodes)
+		return -ENOMEM;
+
+	error = device_property_read_u32_array(&client->dev, "linux,keycodes",
+					       touchkey->keycodes,
+					       touchkey->num_keys);
+
+	if (error) {
+		dev_warn(&client->dev,
+			 "Failed to read keycodes: %d, using defaults\n",
+			 error);
+
+		/* Default keycodes */
+		touchkey->keycodes[0] = KEY_BACK;
+		touchkey->keycodes[1] = KEY_MENU;
+	}
+
+	error = regulator_bulk_enable(ARRAY_SIZE(touchkey->regulators),
+				      touchkey->regulators);
+	if (error) {
+		dev_err(&client->dev,
+			"Failed to enable regulators: %d\n", error);
+		return error;
+	}
+
+	error = devm_add_action_or_reset(&client->dev,
+					 cypress_sf_disable_regulators,
+					 touchkey);
+	if (error)
+		return error;
+
+	touchkey->input_dev = devm_input_allocate_device(&client->dev);
+	if (!touchkey->input_dev) {
+		dev_err(&client->dev, "Failed to allocate input device\n");
+		return -ENOMEM;
+	}
+
+	touchkey->input_dev->name = CYPRESS_SF_DEV_NAME;
+	touchkey->input_dev->id.bustype = BUS_I2C;
+
+	for (key = 0; key < touchkey->num_keys; ++key)
+		input_set_capability(touchkey->input_dev,
+				     EV_KEY, touchkey->keycodes[key]);
+
+	error = input_register_device(touchkey->input_dev);
+	if (error) {
+		dev_err(&client->dev,
+			"Failed to register input device: %d\n", error);
+		return error;
+	}
+
+	error = devm_request_threaded_irq(&client->dev, client->irq,
+					  NULL, cypress_sf_irq_handler,
+					  IRQF_ONESHOT,
+					  CYPRESS_SF_DEV_NAME, touchkey);
+	if (error) {
+		dev_err(&client->dev,
+			"Failed to register threaded irq: %d", error);
+		return error;
+	}
+
+	return 0;
+};
+
+static int cypress_sf_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct cypress_sf_data *touchkey = i2c_get_clientdata(client);
+	int error;
+
+	disable_irq(client->irq);
+
+	error = regulator_bulk_disable(ARRAY_SIZE(touchkey->regulators),
+				       touchkey->regulators);
+	if (error) {
+		dev_err(dev, "Failed to disable regulators: %d", error);
+		enable_irq(client->irq);
+		return error;
+	}
+
+	return 0;
+}
+
+static int cypress_sf_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct cypress_sf_data *touchkey = i2c_get_clientdata(client);
+	int error;
+
+	error = regulator_bulk_enable(ARRAY_SIZE(touchkey->regulators),
+				      touchkey->regulators);
+	if (error) {
+		dev_err(dev, "Failed to enable regulators: %d", error);
+		return error;
+	}
+
+	enable_irq(client->irq);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(cypress_sf_pm_ops,
+				cypress_sf_suspend, cypress_sf_resume);
+
+static const struct i2c_device_id cypress_sf_id_table[] = {
+	{ .name = CYPRESS_SF_DEV_NAME },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, cypress_sf_id_table);
+
+#ifdef CONFIG_OF
+static const struct of_device_id cypress_sf_of_match[] = {
+	{ .compatible = "cypress,sf3155", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, cypress_sf_of_match);
+#endif
+
+static struct i2c_driver cypress_sf_driver = {
+	.driver = {
+		.name = CYPRESS_SF_DEV_NAME,
+		.pm = pm_sleep_ptr(&cypress_sf_pm_ops),
+		.of_match_table = of_match_ptr(cypress_sf_of_match),
+	},
+	.id_table = cypress_sf_id_table,
+	.probe = cypress_sf_probe,
+};
+module_i2c_driver(cypress_sf_driver);
+
+MODULE_AUTHOR("Yassine Oudjana <y.oudjana@protonmail.com>");
+MODULE_DESCRIPTION("Cypress StreetFighter Touchkey Driver");
+MODULE_LICENSE("GPL v2");