From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops 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 --- drivers/usb/misc/usb4604.c | 163 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 163 insertions(+) create mode 100644 drivers/usb/misc/usb4604.c (limited to 'drivers/usb/misc/usb4604.c') diff --git a/drivers/usb/misc/usb4604.c b/drivers/usb/misc/usb4604.c new file mode 100644 index 000000000..2ae965671 --- /dev/null +++ b/drivers/usb/misc/usb4604.c @@ -0,0 +1,163 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Driver for SMSC USB4604 USB HSIC 4-port 2.0 hub controller driver + * Based on usb3503 driver + * + * Copyright (c) 2012-2013 Dongjin Kim (tobetter@gmail.com) + * Copyright (c) 2016 Linaro Ltd. + */ + +#include +#include +#include +#include +#include + +enum usb4604_mode { + USB4604_MODE_UNKNOWN, + USB4604_MODE_HUB, + USB4604_MODE_STANDBY, +}; + +struct usb4604 { + enum usb4604_mode mode; + struct device *dev; + struct gpio_desc *gpio_reset; +}; + +static void usb4604_reset(struct usb4604 *hub, int state) +{ + gpiod_set_value_cansleep(hub->gpio_reset, state); + + /* Wait for i2c logic to come up */ + if (state) + msleep(250); +} + +static int usb4604_connect(struct usb4604 *hub) +{ + struct device *dev = hub->dev; + struct i2c_client *client = to_i2c_client(dev); + int err; + u8 connect_cmd[] = { 0xaa, 0x55, 0x00 }; + + usb4604_reset(hub, 1); + + err = i2c_master_send(client, connect_cmd, ARRAY_SIZE(connect_cmd)); + if (err < 0) { + usb4604_reset(hub, 0); + return err; + } + + hub->mode = USB4604_MODE_HUB; + dev_dbg(dev, "switched to HUB mode\n"); + + return 0; +} + +static int usb4604_switch_mode(struct usb4604 *hub, enum usb4604_mode mode) +{ + struct device *dev = hub->dev; + int err = 0; + + switch (mode) { + case USB4604_MODE_HUB: + err = usb4604_connect(hub); + break; + + case USB4604_MODE_STANDBY: + usb4604_reset(hub, 0); + dev_dbg(dev, "switched to STANDBY mode\n"); + break; + + default: + dev_err(dev, "unknown mode is requested\n"); + err = -EINVAL; + break; + } + + return err; +} + +static int usb4604_probe(struct usb4604 *hub) +{ + struct device *dev = hub->dev; + struct device_node *np = dev->of_node; + struct gpio_desc *gpio; + u32 mode = USB4604_MODE_HUB; + + gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW); + if (IS_ERR(gpio)) + return PTR_ERR(gpio); + hub->gpio_reset = gpio; + + if (of_property_read_u32(np, "initial-mode", &hub->mode)) + hub->mode = mode; + + return usb4604_switch_mode(hub, hub->mode); +} + +static int usb4604_i2c_probe(struct i2c_client *i2c) +{ + struct usb4604 *hub; + + hub = devm_kzalloc(&i2c->dev, sizeof(*hub), GFP_KERNEL); + if (!hub) + return -ENOMEM; + + i2c_set_clientdata(i2c, hub); + hub->dev = &i2c->dev; + + return usb4604_probe(hub); +} + +static int __maybe_unused usb4604_i2c_suspend(struct device *dev) +{ + struct i2c_client *client = to_i2c_client(dev); + struct usb4604 *hub = i2c_get_clientdata(client); + + usb4604_switch_mode(hub, USB4604_MODE_STANDBY); + + return 0; +} + +static int __maybe_unused usb4604_i2c_resume(struct device *dev) +{ + struct i2c_client *client = to_i2c_client(dev); + struct usb4604 *hub = i2c_get_clientdata(client); + + usb4604_switch_mode(hub, hub->mode); + + return 0; +} + +static SIMPLE_DEV_PM_OPS(usb4604_i2c_pm_ops, usb4604_i2c_suspend, + usb4604_i2c_resume); + +static const struct i2c_device_id usb4604_id[] = { + { .name = "usb4604" }, + { } +}; +MODULE_DEVICE_TABLE(i2c, usb4604_id); + +#ifdef CONFIG_OF +static const struct of_device_id usb4604_of_match[] = { + { .compatible = "smsc,usb4604" }, + {} +}; +MODULE_DEVICE_TABLE(of, usb4604_of_match); +#endif + +static struct i2c_driver usb4604_i2c_driver = { + .driver = { + .name = "usb4604", + .pm = pm_ptr(&usb4604_i2c_pm_ops), + .of_match_table = of_match_ptr(usb4604_of_match), + }, + .probe = usb4604_i2c_probe, + .id_table = usb4604_id, +}; +module_i2c_driver(usb4604_i2c_driver); + +MODULE_DESCRIPTION("USB4604 USB HUB driver"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1