ioat_check_space_lock
int ioat_check_space_lock(struct ioatdma_chan *ioat_chan, int num_descs);
ioat_check_space_lock(ioat_chan, num_descs) == 0)
ioat_check_space_lock(ioat_chan, num_descs+1) == 0)
ioat_check_space_lock(ioat_chan, num_descs + cb32) == 0)
if (num_descs && ioat_check_space_lock(ioat_chan, num_descs) == 0)
if (ioat_check_space_lock(ioat_chan, 1) == 0)