[dpdk-stable] [PATCH] net/cxgbe: fix segfault when accessing empty Tx mbuf list

[Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>]

Ensure packets are available before accessing the mbuf list in Tx
burst function. Otherwise, just reclaim completed Tx descriptors and
exit.

Fixes: b1df19e43e1d ("net/cxgbe: fix prefetch for non-coalesced Tx packets")
Cc: stable@dpdk.org

Reported-by: Brian Poole <brian90013@gmail.com>
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
---
 drivers/net/cxgbe/cxgbe_ethdev.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/cxgbe/cxgbe_ethdev.c b/drivers/net/cxgbe/cxgbe_ethdev.c
index 60d325723..38b43772c 100644
--- a/drivers/net/cxgbe/cxgbe_ethdev.c
+++ b/drivers/net/cxgbe/cxgbe_ethdev.c
@@ -71,6 +71,9 @@ uint16_t cxgbe_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 	t4_os_lock(&txq->txq_lock);
 	/* free up desc from already completed tx */
 	reclaim_completed_tx(&txq->q);
+	if (unlikely(!nb_pkts))
+		goto out_unlock;
+
 	rte_prefetch0(rte_pktmbuf_mtod(tx_pkts[0], volatile void *));
 	while (total_sent < nb_pkts) {
 		pkts_remain = nb_pkts - total_sent;
@@ -91,6 +94,7 @@ uint16_t cxgbe_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 		reclaim_completed_tx(&txq->q);
 	}
 
+out_unlock:
 	t4_os_unlock(&txq->txq_lock);
 	return total_sent;
 }
-- 
2.24.0