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, 213 insertions, 0 deletions

diff --git a/drivers/input/keyboard/lm8333.c b/drivers/input/keyboard/lm8333.c
new file mode 100644
index 000000000..34be5b2e4
--- /dev/null
+++ b/drivers/input/keyboard/lm8333.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * LM8333 keypad driver
+ * Copyright (C) 2012 Wolfram Sang, Pengutronix <kernel@pengutronix.de>
+ */
+
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/input/matrix_keypad.h>
+#include <linux/input/lm8333.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#define LM8333_FIFO_READ		0x20
+#define LM8333_DEBOUNCE			0x22
+#define LM8333_READ_INT			0xD0
+#define LM8333_ACTIVE			0xE4
+#define LM8333_READ_ERROR		0xF0
+
+#define LM8333_KEYPAD_IRQ		(1 << 0)
+#define LM8333_ERROR_IRQ		(1 << 3)
+
+#define LM8333_ERROR_KEYOVR		0x04
+#define LM8333_ERROR_FIFOOVR		0x40
+
+#define LM8333_FIFO_TRANSFER_SIZE	16
+
+#define LM8333_NUM_ROWS		8
+#define LM8333_NUM_COLS		16
+#define LM8333_ROW_SHIFT	4
+
+struct lm8333 {
+	struct i2c_client *client;
+	struct input_dev *input;
+	unsigned short keycodes[LM8333_NUM_ROWS << LM8333_ROW_SHIFT];
+};
+
+/* The accessors try twice because the first access may be needed for wakeup */
+#define LM8333_READ_RETRIES 2
+
+int lm8333_read8(struct lm8333 *lm8333, u8 cmd)
+{
+	int retries = 0, ret;
+
+	do {
+		ret = i2c_smbus_read_byte_data(lm8333->client, cmd);
+	} while (ret < 0 && retries++ < LM8333_READ_RETRIES);
+
+	return ret;
+}
+
+int lm8333_write8(struct lm8333 *lm8333, u8 cmd, u8 val)
+{
+	int retries = 0, ret;
+
+	do {
+		ret = i2c_smbus_write_byte_data(lm8333->client, cmd, val);
+	} while (ret < 0 && retries++ < LM8333_READ_RETRIES);
+
+	return ret;
+}
+
+int lm8333_read_block(struct lm8333 *lm8333, u8 cmd, u8 len, u8 *buf)
+{
+	int retries = 0, ret;
+
+	do {
+		ret = i2c_smbus_read_i2c_block_data(lm8333->client,
+						    cmd, len, buf);
+	} while (ret < 0 && retries++ < LM8333_READ_RETRIES);
+
+	return ret;
+}
+
+static void lm8333_key_handler(struct lm8333 *lm8333)
+{
+	struct input_dev *input = lm8333->input;
+	u8 keys[LM8333_FIFO_TRANSFER_SIZE];
+	u8 code, pressed;
+	int i, ret;
+
+	ret = lm8333_read_block(lm8333, LM8333_FIFO_READ,
+				LM8333_FIFO_TRANSFER_SIZE, keys);
+	if (ret != LM8333_FIFO_TRANSFER_SIZE) {
+		dev_err(&lm8333->client->dev,
+			"Error %d while reading FIFO\n", ret);
+		return;
+	}
+
+	for (i = 0; i < LM8333_FIFO_TRANSFER_SIZE && keys[i]; i++) {
+		pressed = keys[i] & 0x80;
+		code = keys[i] & 0x7f;
+
+		input_event(input, EV_MSC, MSC_SCAN, code);
+		input_report_key(input, lm8333->keycodes[code], pressed);
+	}
+
+	input_sync(input);
+}
+
+static irqreturn_t lm8333_irq_thread(int irq, void *data)
+{
+	struct lm8333 *lm8333 = data;
+	u8 status = lm8333_read8(lm8333, LM8333_READ_INT);
+
+	if (!status)
+		return IRQ_NONE;
+
+	if (status & LM8333_ERROR_IRQ) {
+		u8 err = lm8333_read8(lm8333, LM8333_READ_ERROR);
+
+		if (err & (LM8333_ERROR_KEYOVR | LM8333_ERROR_FIFOOVR)) {
+			u8 dummy[LM8333_FIFO_TRANSFER_SIZE];
+
+			lm8333_read_block(lm8333, LM8333_FIFO_READ,
+					LM8333_FIFO_TRANSFER_SIZE, dummy);
+		}
+		dev_err(&lm8333->client->dev, "Got error %02x\n", err);
+	}
+
+	if (status & LM8333_KEYPAD_IRQ)
+		lm8333_key_handler(lm8333);
+
+	return IRQ_HANDLED;
+}
+
+static int lm8333_probe(struct i2c_client *client)
+{
+	const struct lm8333_platform_data *pdata =
+			dev_get_platdata(&client->dev);
+	struct lm8333 *lm8333;
+	struct input_dev *input;
+	int err, active_time;
+
+	if (!pdata)
+		return -EINVAL;
+
+	active_time = pdata->active_time ?: 500;
+	if (active_time / 3 <= pdata->debounce_time / 3) {
+		dev_err(&client->dev, "Active time not big enough!\n");
+		return -EINVAL;
+	}
+
+	lm8333 = devm_kzalloc(&client->dev, sizeof(*lm8333), GFP_KERNEL);
+	if (!lm8333)
+		return -ENOMEM;
+
+	input = devm_input_allocate_device(&client->dev);
+	if (!input)
+		return -ENOMEM;
+
+	lm8333->client = client;
+	lm8333->input = input;
+
+	input->name = client->name;
+	input->id.bustype = BUS_I2C;
+
+	input_set_capability(input, EV_MSC, MSC_SCAN);
+
+	err = matrix_keypad_build_keymap(pdata->matrix_data, NULL,
+					 LM8333_NUM_ROWS, LM8333_NUM_COLS,
+					 lm8333->keycodes, input);
+	if (err)
+		return err;
+
+	if (pdata->debounce_time) {
+		err = lm8333_write8(lm8333, LM8333_DEBOUNCE,
+				    pdata->debounce_time / 3);
+		if (err)
+			dev_warn(&client->dev, "Unable to set debounce time\n");
+	}
+
+	if (pdata->active_time) {
+		err = lm8333_write8(lm8333, LM8333_ACTIVE,
+				    pdata->active_time / 3);
+		if (err)
+			dev_warn(&client->dev, "Unable to set active time\n");
+	}
+
+	err = devm_request_threaded_irq(&client->dev, client->irq,
+					NULL, lm8333_irq_thread,
+					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+					"lm8333", lm8333);
+	if (err)
+		return err;
+
+	err = input_register_device(input);
+	if (err)
+		return err;
+
+	i2c_set_clientdata(client, lm8333);
+	return 0;
+}
+
+static const struct i2c_device_id lm8333_id[] = {
+	{ .name = "lm8333" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, lm8333_id);
+
+static struct i2c_driver lm8333_driver = {
+	.driver = {
+		.name		= "lm8333",
+	},
+	.probe		= lm8333_probe,
+	.id_table	= lm8333_id,
+};
+module_i2c_driver(lm8333_driver);
+
+MODULE_AUTHOR("Wolfram Sang <kernel@pengutronix.de>");
+MODULE_DESCRIPTION("LM8333 keyboard driver");
+MODULE_LICENSE("GPL v2");