net/enic: fix memory leak with oversized Tx packets

If a packet send is attempted with a packet larger than the NIC
is capable of processing (9208) it will be dropped with no
completion descriptor returned or completion index update, which
will lead to an mbuf leak and eventual hang.

Drop and count oversized Tx packets in the Tx burst function and
dereference/free the mbuf without sending it to the NIC.

Since the maximum Rx and Tx packet sizes are different on enic
and are now both being used, make the define ENIC_DEFAULT_MAX_PKT_SIZE
be 2 defines, one for Rx and one for Tx.

Fixes: fefed3d1e6 ("enic: new driver")
Cc: stable@dpdk.org

Signed-off-by: John Daley <johndale@cisco.com>

drivers/net/enic/enic.h

@@ -103,6 +103,7 @@ struct enic_fdir {
 struct enic_soft_stats {
 	rte_atomic64_t rx_nombuf;
 	rte_atomic64_t rx_packet_errors;
+	rte_atomic64_t tx_oversized;
 };
 
 struct enic_memzone_entry {

drivers/net/enic/enic_main.c

@@ -137,6 +137,7 @@ static void enic_clear_soft_stats(struct enic *enic)
 	struct enic_soft_stats *soft_stats = &enic->soft_stats;
 	rte_atomic64_clear(&soft_stats->rx_nombuf);
 	rte_atomic64_clear(&soft_stats->rx_packet_errors);
+	rte_atomic64_clear(&soft_stats->tx_oversized);
 }
 
 static void enic_init_soft_stats(struct enic *enic)
@@ -144,6 +145,7 @@ static void enic_init_soft_stats(struct enic *enic)
 	struct enic_soft_stats *soft_stats = &enic->soft_stats;
 	rte_atomic64_init(&soft_stats->rx_nombuf);
 	rte_atomic64_init(&soft_stats->rx_packet_errors);
+	rte_atomic64_init(&soft_stats->tx_oversized);
 	enic_clear_soft_stats(enic);
 }
 
@@ -183,7 +185,8 @@ void enic_dev_stats_get(struct enic *enic, struct rte_eth_stats *r_stats)
 	r_stats->obytes = stats->tx.tx_bytes_ok;
 
 	r_stats->ierrors = stats->rx.rx_errors + stats->rx.rx_drop;
-	r_stats->oerrors = stats->tx.tx_errors;
+	r_stats->oerrors = stats->tx.tx_errors
+			   + rte_atomic64_read(&soft_stats->tx_oversized);
 
 	r_stats->imissed = stats->rx.rx_no_bufs + rx_truncated;
 

drivers/net/enic/enic_res.c

@@ -89,10 +89,11 @@ int enic_get_vnic_config(struct enic *enic)
 	/* max packet size is only defined in newer VIC firmware
 	 * and will be 0 for legacy firmware and VICs
 	 */
-	if (c->max_pkt_size > ENIC_DEFAULT_MAX_PKT_SIZE)
+	if (c->max_pkt_size > ENIC_DEFAULT_RX_MAX_PKT_SIZE)
 		enic->max_mtu = c->max_pkt_size - (ETHER_HDR_LEN + 4);
 	else
-		enic->max_mtu = ENIC_DEFAULT_MAX_PKT_SIZE - (ETHER_HDR_LEN + 4);
+		enic->max_mtu = ENIC_DEFAULT_RX_MAX_PKT_SIZE
+				- (ETHER_HDR_LEN + 4);
 	if (c->mtu == 0)
 		c->mtu = 1500;
 

drivers/net/enic/enic_res.h

@@ -48,7 +48,10 @@
 #define ENIC_MIN_MTU			68
 
 /* Does not include (possible) inserted VLAN tag and FCS */
-#define ENIC_DEFAULT_MAX_PKT_SIZE	9022
+#define ENIC_DEFAULT_RX_MAX_PKT_SIZE	9022
+
+/* Does not include (possible) inserted VLAN tag and FCS */
+#define ENIC_TX_MAX_PKT_SIZE		9208
 
 #define ENIC_MULTICAST_PERFECT_FILTERS	32
 #define ENIC_UNICAST_PERFECT_FILTERS	32

drivers/net/enic/enic_rxtx.c

@@ -546,16 +546,23 @@ uint16_t enic_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 
 	for (index = 0; index < nb_pkts; index++) {
 		tx_pkt = *tx_pkts++;
+		pkt_len = tx_pkt->pkt_len;
+		data_len = tx_pkt->data_len;
+		ol_flags = tx_pkt->ol_flags;
 		nb_segs = tx_pkt->nb_segs;
+
+		if (pkt_len > ENIC_TX_MAX_PKT_SIZE) {
+			rte_pktmbuf_free(tx_pkt);
+			rte_atomic64_inc(&enic->soft_stats.tx_oversized);
+			continue;
+		}
+
 		if (nb_segs > wq_desc_avail) {
 			if (index > 0)
 				goto post;
 			goto done;
 		}
 
-		pkt_len = tx_pkt->pkt_len;
-		data_len = tx_pkt->data_len;
-		ol_flags = tx_pkt->ol_flags;
 		mss = 0;
 		vlan_id = 0;
 		vlan_tag_insert = 0;