net/pcap: fix byte stats for drop Tx

[ upstream commit cec222d ]

Drop Tx path in pcap is Tx that just drops the packets, which is used
for the case only Rx from a pcap file is requested/matters.

The byte stats was calculated using first mbuf segment, which gives
wrong values for multi segmented mbufs, updated to use packet length
instead.

Bugzilla ID: 597
Fixes: a3f5252 ("net/pcap: enable infinitely Rx a pcap file")

Reported-by: Cian Ferriter <cian.ferriter@intel.com>
Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Cian Ferriter <cian.ferriter@intel.com>

drivers/net/pcap/rte_eth_pcap.c

@@ -386,7 +386,7 @@ eth_tx_drop(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
 		return 0;
 
 	for (i = 0; i < nb_pkts; i++) {
-		tx_bytes += bufs[i]->data_len;
+		tx_bytes += bufs[i]->pkt_len;
 		rte_pktmbuf_free(bufs[i]);
 	}