refill_rx
unsigned int cur_rx, refill_rx;
unsigned int refill_rx = np->refill_rx;
refill_rx++;
np->refill_rx = refill_rx;
if (np->cur_rx - refill_rx == RX_RING)
np->refill_rx = 0;
static void refill_rx(struct nic *nic __unused);
refill_rx(nic);