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, 256 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/zet6223.c b/drivers/input/touchscreen/zet6223.c
new file mode 100644
index 000000000..a341142f3
--- /dev/null
+++ b/drivers/input/touchscreen/zet6223.c
@@ -0,0 +1,256 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2016, Jelle van der Waa <jelle@vdwaa.nl>
+ */
+
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/input/touchscreen.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/unaligned.h>
+
+#define ZET6223_MAX_FINGERS		16
+#define ZET6223_MAX_PKT_SIZE		(3 + 4 * ZET6223_MAX_FINGERS)
+
+#define ZET6223_CMD_INFO		0xB2
+#define ZET6223_CMD_INFO_LENGTH		17
+#define ZET6223_VALID_PACKET		0x3c
+
+#define ZET6223_POWER_ON_DELAY_MSEC	30
+
+struct zet6223_ts {
+	struct i2c_client *client;
+	struct input_dev *input;
+	struct touchscreen_properties prop;
+	struct regulator_bulk_data supplies[2];
+	u16 max_x;
+	u16 max_y;
+	u8 fingernum;
+};
+
+static int zet6223_start(struct input_dev *dev)
+{
+	struct zet6223_ts *ts = input_get_drvdata(dev);
+
+	enable_irq(ts->client->irq);
+
+	return 0;
+}
+
+static void zet6223_stop(struct input_dev *dev)
+{
+	struct zet6223_ts *ts = input_get_drvdata(dev);
+
+	disable_irq(ts->client->irq);
+}
+
+static irqreturn_t zet6223_irq(int irq, void *dev_id)
+{
+	struct zet6223_ts *ts = dev_id;
+	u16 finger_bits;
+
+	/*
+	 * First 3 bytes are an identifier, two bytes of finger data.
+	 * X, Y data per finger is 4 bytes.
+	 */
+	u8 bufsize = 3 + 4 * ts->fingernum;
+	u8 buf[ZET6223_MAX_PKT_SIZE];
+	int i;
+	int ret;
+	int error;
+
+	ret = i2c_master_recv(ts->client, buf, bufsize);
+	if (ret != bufsize) {
+		error = ret < 0 ? ret : -EIO;
+		dev_err_ratelimited(&ts->client->dev,
+				    "Error reading input data: %d\n", error);
+		return IRQ_HANDLED;
+	}
+
+	if (buf[0] != ZET6223_VALID_PACKET)
+		return IRQ_HANDLED;
+
+	finger_bits = get_unaligned_be16(buf + 1);
+	for (i = 0; i < ts->fingernum; i++) {
+		if (!(finger_bits & BIT(15 - i)))
+			continue;
+
+		input_mt_slot(ts->input, i);
+		input_mt_report_slot_state(ts->input, MT_TOOL_FINGER, true);
+		input_event(ts->input, EV_ABS, ABS_MT_POSITION_X,
+				((buf[i + 3] >> 4) << 8) + buf[i + 4]);
+		input_event(ts->input, EV_ABS, ABS_MT_POSITION_Y,
+				((buf[i + 3] & 0xF) << 8) + buf[i + 5]);
+	}
+
+	input_mt_sync_frame(ts->input);
+	input_sync(ts->input);
+
+	return IRQ_HANDLED;
+}
+
+static void zet6223_power_off(void *_ts)
+{
+	struct zet6223_ts *ts = _ts;
+
+	regulator_bulk_disable(ARRAY_SIZE(ts->supplies), ts->supplies);
+}
+
+static int zet6223_power_on(struct zet6223_ts *ts)
+{
+	struct device *dev = &ts->client->dev;
+	int error;
+
+	ts->supplies[0].supply = "vio";
+	ts->supplies[1].supply = "vcc";
+
+	error = devm_regulator_bulk_get(dev, ARRAY_SIZE(ts->supplies),
+					ts->supplies);
+	if (error)
+		return error;
+
+	error = regulator_bulk_enable(ARRAY_SIZE(ts->supplies), ts->supplies);
+	if (error)
+		return error;
+
+	msleep(ZET6223_POWER_ON_DELAY_MSEC);
+
+	error = devm_add_action_or_reset(dev, zet6223_power_off, ts);
+	if (error) {
+		dev_err(dev, "failed to install poweroff action: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int zet6223_query_device(struct zet6223_ts *ts)
+{
+	u8 buf[ZET6223_CMD_INFO_LENGTH];
+	u8 cmd = ZET6223_CMD_INFO;
+	int ret;
+	int error;
+
+	ret = i2c_master_send(ts->client, &cmd, sizeof(cmd));
+	if (ret != sizeof(cmd)) {
+		error = ret < 0 ? ret : -EIO;
+		dev_err(&ts->client->dev,
+			"touchpanel info cmd failed: %d\n", error);
+		return error;
+	}
+
+	ret = i2c_master_recv(ts->client, buf, sizeof(buf));
+	if (ret != sizeof(buf)) {
+		error = ret < 0 ? ret : -EIO;
+		dev_err(&ts->client->dev,
+			"failed to retrieve touchpanel info: %d\n", error);
+		return error;
+	}
+
+	ts->fingernum = buf[15] & 0x7F;
+	if (ts->fingernum > ZET6223_MAX_FINGERS) {
+		dev_warn(&ts->client->dev,
+			 "touchpanel reports %d fingers, limiting to %d\n",
+			 ts->fingernum, ZET6223_MAX_FINGERS);
+		ts->fingernum = ZET6223_MAX_FINGERS;
+	}
+
+	ts->max_x = get_unaligned_le16(&buf[8]);
+	ts->max_y = get_unaligned_le16(&buf[10]);
+
+	return 0;
+}
+
+static int zet6223_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct zet6223_ts *ts;
+	struct input_dev *input;
+	int error;
+
+	if (!client->irq) {
+		dev_err(dev, "no irq specified\n");
+		return -EINVAL;
+	}
+
+	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	ts->client = client;
+
+	error = zet6223_power_on(ts);
+	if (error)
+		return error;
+
+	error = zet6223_query_device(ts);
+	if (error)
+		return error;
+
+	ts->input = input = devm_input_allocate_device(dev);
+	if (!input)
+		return -ENOMEM;
+
+	input_set_drvdata(input, ts);
+
+	input->name = client->name;
+	input->id.bustype = BUS_I2C;
+	input->open = zet6223_start;
+	input->close = zet6223_stop;
+
+	input_set_abs_params(input, ABS_MT_POSITION_X, 0, ts->max_x, 0, 0);
+	input_set_abs_params(input, ABS_MT_POSITION_Y, 0, ts->max_y, 0, 0);
+
+	touchscreen_parse_properties(input, true, &ts->prop);
+
+	error = input_mt_init_slots(input, ts->fingernum,
+				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+	if (error)
+		return error;
+
+	error = devm_request_threaded_irq(dev, client->irq, NULL, zet6223_irq,
+					  IRQF_ONESHOT, client->name, ts);
+	if (error) {
+		dev_err(dev, "failed to request irq %d: %d\n",
+			client->irq, error);
+		return error;
+	}
+
+	zet6223_stop(input);
+
+	error = input_register_device(input);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+static const struct of_device_id zet6223_of_match[] = {
+	{ .compatible = "zeitec,zet6223" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, zet6223_of_match);
+
+static const struct i2c_device_id zet6223_id[] = {
+	{ .name = "zet6223" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, zet6223_id);
+
+static struct i2c_driver zet6223_driver = {
+	.driver = {
+		.name = "zet6223",
+		.of_match_table = zet6223_of_match,
+	},
+	.probe = zet6223_probe,
+	.id_table = zet6223_id
+};
+module_i2c_driver(zet6223_driver);
+
+MODULE_AUTHOR("Jelle van der Waa <jelle@vdwaa.nl>");
+MODULE_DESCRIPTION("ZEITEC zet622x I2C touchscreen driver");
+MODULE_LICENSE("GPL");