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/serial/bus.c | 171 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 171 insertions(+) create mode 100644 drivers/usb/serial/bus.c (limited to 'drivers/usb/serial/bus.c') diff --git a/drivers/usb/serial/bus.c b/drivers/usb/serial/bus.c new file mode 100644 index 000000000..9e2a18c0b --- /dev/null +++ b/drivers/usb/serial/bus.c @@ -0,0 +1,171 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * USB Serial Converter Bus specific functions + * + * Copyright (C) 2002 Greg Kroah-Hartman (greg@kroah.com) + */ + +#include +#include +#include +#include +#include +#include +#include + +static int usb_serial_device_match(struct device *dev, + const struct device_driver *drv) +{ + const struct usb_serial_port *port = to_usb_serial_port(dev); + const struct usb_serial_driver *driver = to_usb_serial_driver(drv); + + /* + * drivers are already assigned to ports in serial_probe so it's + * a simple check here. + */ + if (driver == port->serial->type) + return 1; + + return 0; +} + +static int usb_serial_device_probe(struct device *dev) +{ + struct usb_serial_port *port = to_usb_serial_port(dev); + struct usb_serial_driver *driver; + struct device *tty_dev; + int retval = 0; + int minor; + + /* make sure suspend/resume doesn't race against port_probe */ + retval = usb_autopm_get_interface(port->serial->interface); + if (retval) + return retval; + + driver = port->serial->type; + if (driver->port_probe) { + retval = driver->port_probe(port); + if (retval) + goto err_autopm_put; + } + + minor = port->minor; + tty_dev = tty_port_register_device(&port->port, usb_serial_tty_driver, + minor, dev); + if (IS_ERR(tty_dev)) { + retval = PTR_ERR(tty_dev); + goto err_port_remove; + } + + usb_autopm_put_interface(port->serial->interface); + + dev_info(&port->serial->dev->dev, + "%s converter now attached to ttyUSB%d\n", + driver->description, minor); + + return 0; + +err_port_remove: + if (driver->port_remove) + driver->port_remove(port); +err_autopm_put: + usb_autopm_put_interface(port->serial->interface); + + return retval; +} + +static void usb_serial_device_remove(struct device *dev) +{ + struct usb_serial_port *port = to_usb_serial_port(dev); + struct usb_serial_driver *driver; + int minor; + int autopm_err; + + /* + * Make sure suspend/resume doesn't race against port_remove. + * + * Note that no further runtime PM callbacks will be made if + * autopm_get fails. + */ + autopm_err = usb_autopm_get_interface(port->serial->interface); + + minor = port->minor; + tty_unregister_device(usb_serial_tty_driver, minor); + + driver = port->serial->type; + if (driver->port_remove) + driver->port_remove(port); + + dev_info(dev, "%s converter now disconnected from ttyUSB%d\n", + driver->description, minor); + + if (!autopm_err) + usb_autopm_put_interface(port->serial->interface); +} + +static ssize_t new_id_store(struct device_driver *driver, + const char *buf, size_t count) +{ + struct usb_serial_driver *usb_drv = to_usb_serial_driver(driver); + ssize_t retval = usb_store_new_id(&usb_drv->dynids, usb_drv->id_table, + driver, buf, count); + + if (retval >= 0 && usb_drv->usb_driver != NULL) + retval = usb_store_new_id(&usb_drv->usb_driver->dynids, + usb_drv->usb_driver->id_table, + &usb_drv->usb_driver->driver, + buf, count); + return retval; +} + +static ssize_t new_id_show(struct device_driver *driver, char *buf) +{ + struct usb_serial_driver *usb_drv = to_usb_serial_driver(driver); + + return usb_show_dynids(&usb_drv->dynids, buf); +} +static DRIVER_ATTR_RW(new_id); + +static struct attribute *usb_serial_drv_attrs[] = { + &driver_attr_new_id.attr, + NULL, +}; +ATTRIBUTE_GROUPS(usb_serial_drv); + +static void free_dynids(struct usb_serial_driver *drv) +{ + struct usb_dynid *dynid, *n; + + guard(mutex)(&usb_dynids_lock); + list_for_each_entry_safe(dynid, n, &drv->dynids.list, node) { + list_del(&dynid->node); + kfree(dynid); + } +} + +const struct bus_type usb_serial_bus_type = { + .name = "usb-serial", + .match = usb_serial_device_match, + .probe = usb_serial_device_probe, + .remove = usb_serial_device_remove, + .drv_groups = usb_serial_drv_groups, +}; + +int usb_serial_bus_register(struct usb_serial_driver *driver) +{ + int retval; + + driver->driver.bus = &usb_serial_bus_type; + INIT_LIST_HEAD(&driver->dynids.list); + + retval = driver_register(&driver->driver); + + return retval; +} + +void usb_serial_bus_deregister(struct usb_serial_driver *driver) +{ + free_dynids(driver); + driver_unregister(&driver->driver); +} + -- cgit v1.3.1