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, 89 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/tsc2005.c b/drivers/input/touchscreen/tsc2005.c
new file mode 100644
index 000000000..6fe8b41b3
--- /dev/null
+++ b/drivers/input/touchscreen/tsc2005.c
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * TSC2005 touchscreen driver
+ *
+ * Copyright (C) 2006-2010 Nokia Corporation
+ * Copyright (C) 2015 QWERTY Embedded Design
+ * Copyright (C) 2015 EMAC Inc.
+ *
+ * Based on original tsc2005.c by Lauri Leukkunen <lauri.leukkunen@nokia.com>
+ */
+
+#include <linux/input.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/spi/spi.h>
+#include <linux/regmap.h>
+#include "tsc200x-core.h"
+
+static const struct input_id tsc2005_input_id = {
+	.bustype = BUS_SPI,
+	.product = 2005,
+};
+
+static int tsc2005_cmd(struct device *dev, u8 cmd)
+{
+	u8 tx = TSC200X_CMD | TSC200X_CMD_12BIT | cmd;
+	struct spi_transfer xfer = {
+		.tx_buf         = &tx,
+		.len            = 1,
+		.bits_per_word  = 8,
+	};
+	struct spi_message msg;
+	struct spi_device *spi = to_spi_device(dev);
+	int error;
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfer, &msg);
+
+	error = spi_sync(spi, &msg);
+	if (error) {
+		dev_err(dev, "%s: failed, command: %x, spi error: %d\n",
+			__func__, cmd, error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int tsc2005_probe(struct spi_device *spi)
+{
+	int error;
+
+	spi->mode = SPI_MODE_0;
+	spi->bits_per_word = 8;
+	if (!spi->max_speed_hz)
+		spi->max_speed_hz = TSC2005_SPI_MAX_SPEED_HZ;
+
+	error = spi_setup(spi);
+	if (error)
+		return error;
+
+	return tsc200x_probe(&spi->dev, spi->irq, &tsc2005_input_id,
+			     devm_regmap_init_spi(spi, &tsc200x_regmap_config),
+			     tsc2005_cmd);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id tsc2005_of_match[] = {
+	{ .compatible = "ti,tsc2005" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, tsc2005_of_match);
+#endif
+
+static struct spi_driver tsc2005_driver = {
+	.driver	= {
+		.name		= "tsc2005",
+		.dev_groups	= tsc200x_groups,
+		.of_match_table	= of_match_ptr(tsc2005_of_match),
+		.pm		= pm_sleep_ptr(&tsc200x_pm_ops),
+	},
+	.probe	= tsc2005_probe,
+};
+module_spi_driver(tsc2005_driver);
+
+MODULE_AUTHOR("Michael Welling <mwelling@ieee.org>");
+MODULE_DESCRIPTION("TSC2005 Touchscreen Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("spi:tsc2005");