systemtap

#!/usr/local/bin/stap -vg
%{
        #include <linux/usb.h>
        #include <linux/device.h>
%}

global var;
%{
static int get_usb_dev(struct usb_device *dev, void *p) {
        /* pragma:write:var*/
        STAP_GLOBAL_SET_var(dev);
        return 0;
}
%}
function get_all_usb_dev () %{
        usb_for_each_dev(NULL, get_usb_dev);
%}

probe begin {
        get_all_usb_dev();
        print(var);
        exit();
}