net: fec: fix improper use of NETDEV_TX_BUSY

The ndo_start_xmit() method must not free skb when returning
NETDEV_TX_BUSY, since caller is going to requeue freed skb.

Fix it by returning NETDEV_TX_OK in case of dma_map_single() fails.

Fixes: 79f33912 ("net: fec: Add software TSO support")
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/fec_main.c

@@ -713,7 +713,7 @@ fec_enet_txq_put_data_tso(struct fec_enet_priv_tx_q *txq, struct sk_buff *skb,
 		dev_kfree_skb_any(skb);
 		if (net_ratelimit())
 			netdev_err(ndev, "Tx DMA memory map failed\n");
-		return NETDEV_TX_BUSY;
+		return NETDEV_TX_OK;
 	}
 
 	bdp->cbd_datlen = cpu_to_fec16(size);
@@ -775,7 +775,7 @@ fec_enet_txq_put_hdr_tso(struct fec_enet_priv_tx_q *txq,
 			dev_kfree_skb_any(skb);
 			if (net_ratelimit())
 				netdev_err(ndev, "Tx DMA memory map failed\n");
-			return NETDEV_TX_BUSY;
+			return NETDEV_TX_OK;
 		}
 	}