Man page 9 : usb_get_dev

usb_get_dev - increments the reference count of the usb device structure

struct usb_device * usb_get_dev(struct usb_device *  dev );

dev
    the device being referenced

Each live reference to a device should be refcounted.

Drivers for USB interfaces should normally record such references in their probe methods, when they bind to an interface, and release them by calling usb_put_dev, in their disconnect methods.

A pointer to the device with the incremented reference counter is returned.