dev_queue_xmit -- transmit a buffer
(struct sk_buff * skb);
Queue a buffer for transmission to a network device. The caller must
have set the device and priority and built the buffer before calling this
function. The function can be called from an interrupt.
A negative errno code is returned on a failure. A success does not
guarantee the frame will be transmitted as it may be dropped due
to congestion or traffic shaping.