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, 163 insertions, 0 deletions

diff --git a/drivers/usb/phy/phy-isp1301.c b/drivers/usb/phy/phy-isp1301.c
new file mode 100644
index 000000000..73cc70e95
--- /dev/null
+++ b/drivers/usb/phy/phy-isp1301.c
@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * NXP ISP1301 USB transceiver driver
+ *
+ * Copyright (C) 2012 Roland Stigge
+ *
+ * Author: Roland Stigge <stigge@antcom.de>
+ */
+
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/i2c.h>
+#include <linux/usb/phy.h>
+#include <linux/usb/isp1301.h>
+
+#define DRV_NAME		"isp1301"
+
+struct isp1301 {
+	struct usb_phy		phy;
+	struct mutex		mutex;
+
+	struct i2c_client	*client;
+};
+
+#define phy_to_isp(p)		(container_of((p), struct isp1301, phy))
+
+static const struct i2c_device_id isp1301_id[] = {
+	{ .name = "isp1301" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, isp1301_id);
+
+static const struct of_device_id isp1301_of_match[] = {
+	{.compatible = "nxp,isp1301" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, isp1301_of_match);
+
+static struct i2c_client *isp1301_i2c_client;
+
+static int __isp1301_write(struct isp1301 *isp, u8 reg, u8 value, u8 clear)
+{
+	return i2c_smbus_write_byte_data(isp->client, reg | clear, value);
+}
+
+static int isp1301_write(struct isp1301 *isp, u8 reg, u8 value)
+{
+	return __isp1301_write(isp, reg, value, 0);
+}
+
+static int isp1301_clear(struct isp1301 *isp, u8 reg, u8 value)
+{
+	return __isp1301_write(isp, reg, value, ISP1301_I2C_REG_CLEAR_ADDR);
+}
+
+static int isp1301_phy_init(struct usb_phy *phy)
+{
+	struct isp1301 *isp = phy_to_isp(phy);
+
+	/* Disable transparent UART mode first */
+	isp1301_clear(isp, ISP1301_I2C_MODE_CONTROL_1, MC1_UART_EN);
+	isp1301_clear(isp, ISP1301_I2C_MODE_CONTROL_1, ~MC1_SPEED_REG);
+	isp1301_write(isp, ISP1301_I2C_MODE_CONTROL_1, MC1_SPEED_REG);
+	isp1301_clear(isp, ISP1301_I2C_MODE_CONTROL_2, ~0);
+	isp1301_write(isp, ISP1301_I2C_MODE_CONTROL_2, (MC2_BI_DI | MC2_PSW_EN
+				| MC2_SPD_SUSP_CTRL));
+
+	isp1301_clear(isp, ISP1301_I2C_OTG_CONTROL_1, ~0);
+	isp1301_write(isp, ISP1301_I2C_MODE_CONTROL_1, MC1_DAT_SE0);
+	isp1301_write(isp, ISP1301_I2C_OTG_CONTROL_1, (OTG1_DM_PULLDOWN
+				| OTG1_DP_PULLDOWN));
+	isp1301_clear(isp, ISP1301_I2C_OTG_CONTROL_1, (OTG1_DM_PULLUP
+				| OTG1_DP_PULLUP));
+
+	/* mask all interrupts */
+	isp1301_clear(isp, ISP1301_I2C_INTERRUPT_LATCH, ~0);
+	isp1301_clear(isp, ISP1301_I2C_INTERRUPT_FALLING, ~0);
+	isp1301_clear(isp, ISP1301_I2C_INTERRUPT_RISING, ~0);
+
+	return 0;
+}
+
+static int isp1301_phy_set_vbus(struct usb_phy *phy, int on)
+{
+	struct isp1301 *isp = phy_to_isp(phy);
+
+	if (on)
+		isp1301_write(isp, ISP1301_I2C_OTG_CONTROL_1, OTG1_VBUS_DRV);
+	else
+		isp1301_clear(isp, ISP1301_I2C_OTG_CONTROL_1, OTG1_VBUS_DRV);
+
+	return 0;
+}
+
+static int isp1301_probe(struct i2c_client *client)
+{
+	struct isp1301 *isp;
+	struct usb_phy *phy;
+
+	isp = devm_kzalloc(&client->dev, sizeof(*isp), GFP_KERNEL);
+	if (!isp)
+		return -ENOMEM;
+
+	isp->client = client;
+	mutex_init(&isp->mutex);
+
+	phy = &isp->phy;
+	phy->dev = &client->dev;
+	phy->label = DRV_NAME;
+	phy->init = isp1301_phy_init;
+	phy->set_vbus = isp1301_phy_set_vbus;
+	phy->type = USB_PHY_TYPE_USB2;
+
+	i2c_set_clientdata(client, isp);
+	usb_add_phy_dev(phy);
+
+	isp1301_i2c_client = client;
+
+	return 0;
+}
+
+static void isp1301_remove(struct i2c_client *client)
+{
+	struct isp1301 *isp = i2c_get_clientdata(client);
+
+	usb_remove_phy(&isp->phy);
+	isp1301_i2c_client = NULL;
+}
+
+static struct i2c_driver isp1301_driver = {
+	.driver = {
+		.name = DRV_NAME,
+		.of_match_table = isp1301_of_match,
+	},
+	.probe = isp1301_probe,
+	.remove = isp1301_remove,
+	.id_table = isp1301_id,
+};
+
+module_i2c_driver(isp1301_driver);
+
+struct i2c_client *isp1301_get_client(struct device_node *node)
+{
+	struct i2c_client *client;
+
+	/* reference of ISP1301 I2C node via DT */
+	client = of_find_i2c_device_by_node(node);
+	if (client)
+		return client;
+
+	/* non-DT: only one ISP1301 chip supported */
+	if (isp1301_i2c_client) {
+		get_device(&isp1301_i2c_client->dev);
+		return isp1301_i2c_client;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(isp1301_get_client);
+
+MODULE_AUTHOR("Roland Stigge <stigge@antcom.de>");
+MODULE_DESCRIPTION("NXP ISP1301 USB transceiver driver");
+MODULE_LICENSE("GPL");