sk_tx_desc
struct sk_tx_desc *f = NULL;
struct sk_tx_desc *desc;
struct sk_tx_desc *cur_tx;
void sk_dump_txdesc(struct sk_tx_desc *, int);
sk_dump_txdesc(struct sk_tx_desc *desc, int idx)
sizeof(struct sk_tx_desc) * SK_TX_RING_CNT);
struct sk_tx_desc sk_tx_ring[SK_TX_RING_CNT];
sizeof(struct sk_tx_desc) * (SK_TX_RING_CNT - __x),\
SK_CDTXOFF((__x)), sizeof(struct sk_tx_desc) * __n, (ops)); \