nfp: count all failed TX attempts as errors

Currently if we need to modify the head of the skb and allocation
fails we would free the skb and not increment the error counter.
Make sure all errors are counted.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/nfp_net_common.c

@@ -873,17 +873,14 @@ static int nfp_net_tx(struct sk_buff *skb, struct net_device *netdev)
 	}
 
 	md_bytes = nfp_net_prep_port_id(skb);
-	if (unlikely(md_bytes < 0)) {
-		nfp_net_tx_xmit_more_flush(tx_ring);
-		dev_kfree_skb_any(skb);
-		return NETDEV_TX_OK;
-	}
+	if (unlikely(md_bytes < 0))
+		goto err_flush;
 
 	/* Start with the head skbuf */
 	dma_addr = dma_map_single(dp->dev, skb->data, skb_headlen(skb),
 				  DMA_TO_DEVICE);
 	if (dma_mapping_error(dp->dev, dma_addr))
-		goto err_free;
+		goto err_dma_err;
 
 	wr_idx = D_IDX(tx_ring, tx_ring->wr_p);
 
@@ -979,8 +976,9 @@ static int nfp_net_tx(struct sk_buff *skb, struct net_device *netdev)
 	tx_ring->txbufs[wr_idx].skb = NULL;
 	tx_ring->txbufs[wr_idx].dma_addr = 0;
 	tx_ring->txbufs[wr_idx].fidx = -2;
-err_free:
+err_dma_err:
 	nn_dp_warn(dp, "Failed to map DMA TX buffer\n");
+err_flush:
 	nfp_net_tx_xmit_more_flush(tx_ring);
 	u64_stats_update_begin(&r_vec->tx_sync);
 	r_vec->tx_errors++;