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, 129 insertions, 0 deletions

diff --git a/drivers/mfd/stmpe-i2c.c b/drivers/mfd/stmpe-i2c.c
new file mode 100644
index 000000000..943fa363e
--- /dev/null
+++ b/drivers/mfd/stmpe-i2c.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ST Microelectronics MFD: stmpe's i2c client specific driver
+ *
+ * Copyright (C) ST-Ericsson SA 2010
+ * Copyright (C) ST Microelectronics SA 2011
+ *
+ * Author: Rabin Vincent <rabin.vincent@stericsson.com> for ST-Ericsson
+ * Author: Viresh Kumar <vireshk@kernel.org> for ST Microelectronics
+ */
+
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/of_device.h>
+#include "stmpe.h"
+
+static int i2c_reg_read(struct stmpe *stmpe, u8 reg)
+{
+	struct i2c_client *i2c = stmpe->client;
+
+	return i2c_smbus_read_byte_data(i2c, reg);
+}
+
+static int i2c_reg_write(struct stmpe *stmpe, u8 reg, u8 val)
+{
+	struct i2c_client *i2c = stmpe->client;
+
+	return i2c_smbus_write_byte_data(i2c, reg, val);
+}
+
+static int i2c_block_read(struct stmpe *stmpe, u8 reg, u8 length, u8 *values)
+{
+	struct i2c_client *i2c = stmpe->client;
+
+	return i2c_smbus_read_i2c_block_data(i2c, reg, length, values);
+}
+
+static int i2c_block_write(struct stmpe *stmpe, u8 reg, u8 length,
+		const u8 *values)
+{
+	struct i2c_client *i2c = stmpe->client;
+
+	return i2c_smbus_write_i2c_block_data(i2c, reg, length, values);
+}
+
+static struct stmpe_client_info i2c_ci = {
+	.read_byte = i2c_reg_read,
+	.write_byte = i2c_reg_write,
+	.read_block = i2c_block_read,
+	.write_block = i2c_block_write,
+};
+
+static const struct of_device_id stmpe_of_match[] = {
+	{ .compatible = "st,stmpe610", .data = (void *)STMPE610, },
+	{ .compatible = "st,stmpe801", .data = (void *)STMPE801, },
+	{ .compatible = "st,stmpe811", .data = (void *)STMPE811, },
+	{ .compatible = "st,stmpe1600", .data = (void *)STMPE1600, },
+	{ .compatible = "st,stmpe1601", .data = (void *)STMPE1601, },
+	{ .compatible = "st,stmpe1801", .data = (void *)STMPE1801, },
+	{ .compatible = "st,stmpe2401", .data = (void *)STMPE2401, },
+	{ .compatible = "st,stmpe2403", .data = (void *)STMPE2403, },
+	{},
+};
+MODULE_DEVICE_TABLE(of, stmpe_of_match);
+
+static int
+stmpe_i2c_probe(struct i2c_client *i2c)
+{
+	const struct i2c_device_id *id = i2c_client_get_device_id(i2c);
+	enum stmpe_partnum partnum;
+	const struct of_device_id *of_id;
+
+	i2c_ci.data = (void *)id;
+	i2c_ci.irq = i2c->irq;
+	i2c_ci.client = i2c;
+	i2c_ci.dev = &i2c->dev;
+
+	of_id = of_match_device(stmpe_of_match, &i2c->dev);
+	if (!of_id) {
+		/*
+		 * This happens when the I2C ID matches the node name
+		 * but no real compatible string has been given.
+		 */
+		dev_info(&i2c->dev, "matching on node name, compatible is preferred\n");
+		partnum = id->driver_data;
+	} else
+		partnum = (uintptr_t)of_id->data;
+
+	return stmpe_probe(&i2c_ci, partnum);
+}
+
+static void stmpe_i2c_remove(struct i2c_client *i2c)
+{
+	struct stmpe *stmpe = dev_get_drvdata(&i2c->dev);
+
+	stmpe_remove(stmpe);
+}
+
+static const struct i2c_device_id stmpe_i2c_id[] = {
+	{ "stmpe610", STMPE610 },
+	{ "stmpe801", STMPE801 },
+	{ "stmpe811", STMPE811 },
+	{ "stmpe1600", STMPE1600 },
+	{ "stmpe1601", STMPE1601 },
+	{ "stmpe1801", STMPE1801 },
+	{ "stmpe2401", STMPE2401 },
+	{ "stmpe2403", STMPE2403 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, stmpe_i2c_id);
+
+static struct i2c_driver stmpe_i2c_driver = {
+	.driver = {
+		.name = "stmpe-i2c",
+		.pm = pm_sleep_ptr(&stmpe_dev_pm_ops),
+		.of_match_table = stmpe_of_match,
+	},
+	.probe		= stmpe_i2c_probe,
+	.remove		= stmpe_i2c_remove,
+	.id_table	= stmpe_i2c_id,
+};
+module_i2c_driver(stmpe_i2c_driver);
+
+MODULE_DESCRIPTION("STMPE MFD I2C Interface Driver");
+MODULE_AUTHOR("Rabin Vincent <rabin.vincent@stericsson.com>");
+MODULE_LICENSE("GPL");