Man page 9 : usb_queue_reset_device

usb_queue_reset_device - Reset a USB device from an atomic context

void usb_queue_reset_device(struct usb_interface *  iface );

iface
    USB interface belonging to the device to reset

This function can be used to reset a USB device from an atomic context, where usb_reset_device wonAqt work (as it blocks).

Doing a reset via this method is functionally equivalent to calling usb_reset_device, except for the fact that it is delayed to a workqueue. This means that any drivers bound to other interfaces might be unbound, as well as users from usbfs in user space.

- Scheduling two resets at the same time from two different drivers attached to two different interfaces of the same device is possible; depending on how the driver attached to each interface handles ->pre_reset, the second reset might happen or not.

- If a driver is unbound and it had a pending reset, the reset will be cancelled.

- This function can be called during .probe or .disconnect times. On return from .disconnect, any pending resets will be cancelled.

There is no no need to lock/unlock the reset_ws as schedule_work does its own.

We donAqt do any reference count tracking because it is not needed. The lifecycle of the work_struct is tied to the usb_interface. Before destroying the interface we cancel the work_struct, so the fact that work_struct is queued and or running means the interface (and thus, the device) exist and are referenced.