USB_ATTACH_SETUP macros question

[Tofig Suleymanov]

Hello hackers,

is there anybody to explain why do we have infinite loop inside of
USB_ATTACH_SETUP macros inside of usb_port.h ? How does his loop gets
escaped when we use it in some usb driver ?

#define USB_ATTACH_SETUP \
        do { \
                sc->sc_dev = self; \
                device_set_desc_copy(self, devinfo); \
                device_printf(self, "%s\n", devinfo); \
        } while (0);

Thank you  !

Tofig Suleymanov