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, 142 insertions, 0 deletions

diff --git a/drivers/mfd/tps6507x.c b/drivers/mfd/tps6507x.c
new file mode 100644
index 000000000..9865512dc
--- /dev/null
+++ b/drivers/mfd/tps6507x.c
@@ -0,0 +1,142 @@
+/*
+ * tps6507x.c  --  TPS6507x chip family multi-function driver
+ *
+ *  Copyright (c) 2010 RidgeRun (todd.fischer@ridgerun.com)
+ *
+ * Author: Todd Fischer
+ *         todd.fischer@ridgerun.com
+ *
+ * Credits:
+ *
+ *    Using code from wm831x-*.c, wm8400-core, Wolfson Microelectronics PLC.
+ *
+ * For licencing details see kernel-base/COPYING
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/of.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/tps6507x.h>
+
+static const struct mfd_cell tps6507x_devs[] = {
+	{
+		.name = "tps6507x-pmic",
+	},
+	{
+		.name = "tps6507x-ts",
+	},
+};
+
+
+static int tps6507x_i2c_read_device(struct tps6507x_dev *tps6507x, char reg,
+				  int bytes, void *dest)
+{
+	struct i2c_client *i2c = tps6507x->i2c_client;
+	struct i2c_msg xfer[2];
+	int ret;
+
+	/* Write register */
+	xfer[0].addr = i2c->addr;
+	xfer[0].flags = 0;
+	xfer[0].len = 1;
+	xfer[0].buf = &reg;
+
+	/* Read data */
+	xfer[1].addr = i2c->addr;
+	xfer[1].flags = I2C_M_RD;
+	xfer[1].len = bytes;
+	xfer[1].buf = dest;
+
+	ret = i2c_transfer(i2c->adapter, xfer, 2);
+	if (ret == 2)
+		ret = 0;
+	else if (ret >= 0)
+		ret = -EIO;
+
+	return ret;
+}
+
+static int tps6507x_i2c_write_device(struct tps6507x_dev *tps6507x, char reg,
+				   int bytes, void *src)
+{
+	struct i2c_client *i2c = tps6507x->i2c_client;
+	/* we add 1 byte for device register */
+	u8 msg[TPS6507X_MAX_REGISTER + 1];
+	int ret;
+
+	if (bytes > TPS6507X_MAX_REGISTER)
+		return -EINVAL;
+
+	msg[0] = reg;
+	memcpy(&msg[1], src, bytes);
+
+	ret = i2c_master_send(i2c, msg, bytes + 1);
+	if (ret < 0)
+		return ret;
+	if (ret != bytes + 1)
+		return -EIO;
+	return 0;
+}
+
+static int tps6507x_i2c_probe(struct i2c_client *i2c)
+{
+	struct tps6507x_dev *tps6507x;
+
+	tps6507x = devm_kzalloc(&i2c->dev, sizeof(struct tps6507x_dev),
+				GFP_KERNEL);
+	if (tps6507x == NULL)
+		return -ENOMEM;
+
+	i2c_set_clientdata(i2c, tps6507x);
+	tps6507x->dev = &i2c->dev;
+	tps6507x->i2c_client = i2c;
+	tps6507x->read_dev = tps6507x_i2c_read_device;
+	tps6507x->write_dev = tps6507x_i2c_write_device;
+
+	return devm_mfd_add_devices(tps6507x->dev, -1, tps6507x_devs,
+				    ARRAY_SIZE(tps6507x_devs), NULL, 0, NULL);
+}
+
+static const struct i2c_device_id tps6507x_i2c_id[] = {
+	{ "tps6507x" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tps6507x_i2c_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id tps6507x_of_match[] = {
+	{.compatible = "ti,tps6507x", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, tps6507x_of_match);
+#endif
+
+static struct i2c_driver tps6507x_i2c_driver = {
+	.driver = {
+		   .name = "tps6507x",
+		   .of_match_table = of_match_ptr(tps6507x_of_match),
+	},
+	.probe = tps6507x_i2c_probe,
+	.id_table = tps6507x_i2c_id,
+};
+
+static int __init tps6507x_i2c_init(void)
+{
+	return i2c_add_driver(&tps6507x_i2c_driver);
+}
+/* init early so consumer devices can complete system boot */
+subsys_initcall(tps6507x_i2c_init);
+
+static void __exit tps6507x_i2c_exit(void)
+{
+	i2c_del_driver(&tps6507x_i2c_driver);
+}
+module_exit(tps6507x_i2c_exit);
+
+MODULE_DESCRIPTION("TPS6507x chip family multi-function driver");
+MODULE_LICENSE("GPL");