net: ravb: Refactor GbEth RX code path

We can reduce code duplication in ravb_rx_gbeth().
Signed-off-by: Paul Barker <paul.barker.ct@bp.renesas.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/renesas/ravb_main.c

@@ -819,47 +819,52 @@ static int ravb_rx_gbeth(struct net_device *ndev, int budget, int q)
 				stats->rx_missed_errors++;
 		} else {
 			die_dt = desc->die_dt & 0xF0;
+			skb = ravb_get_skb_gbeth(ndev, entry, desc);
 			switch (die_dt) {
 			case DT_FSINGLE:
-				skb = ravb_get_skb_gbeth(ndev, entry, desc);
-				skb_put(skb, desc_len);
-				skb->protocol = eth_type_trans(skb, ndev);
-				if (ndev->features & NETIF_F_RXCSUM)
-					ravb_rx_csum_gbeth(skb);
-				napi_gro_receive(&priv->napi[q], skb);
-				rx_packets++;
-				stats->rx_bytes += desc_len;
-				break;
 			case DT_FSTART:
-				priv->rx_1st_skb = ravb_get_skb_gbeth(ndev, entry, desc);
-				skb_put(priv->rx_1st_skb, desc_len);
+				/* Start of packet: Set initial data length. */
+				skb_put(skb, desc_len);
+
+				/* Save this skb if the packet spans multiple
+				 * descriptors.
+				 */
+				if (die_dt == DT_FSTART)
+					priv->rx_1st_skb = skb;
 				break;
+
 			case DT_FMID:
-				skb = ravb_get_skb_gbeth(ndev, entry, desc);
-				skb_copy_to_linear_data_offset(priv->rx_1st_skb,
-							       priv->rx_1st_skb->len,
-							       skb->data,
-							       desc_len);
-				skb_put(priv->rx_1st_skb, desc_len);
-				dev_kfree_skb(skb);
-				break;
 			case DT_FEND:
-				skb = ravb_get_skb_gbeth(ndev, entry, desc);
+				/* Continuing a packet: Move data into the saved
+				 * skb.
+				 */
 				skb_copy_to_linear_data_offset(priv->rx_1st_skb,
 							       priv->rx_1st_skb->len,
 							       skb->data,
 							       desc_len);
 				skb_put(priv->rx_1st_skb, desc_len);
 				dev_kfree_skb(skb);
-				priv->rx_1st_skb->protocol =
-					eth_type_trans(priv->rx_1st_skb, ndev);
+
+				/* Set skb to point at the whole packet so that
+				 * we only need one code path for finishing a
+				 * packet.
+				 */
+				skb = priv->rx_1st_skb;
+			}
+
+			switch (die_dt) {
+			case DT_FSINGLE:
+			case DT_FEND:
+				/* Finishing a packet: Determine protocol &
+				 * checksum, hand off to NAPI and update our
+				 * stats.
+				 */
+				skb->protocol = eth_type_trans(skb, ndev);
 				if (ndev->features & NETIF_F_RXCSUM)
-					ravb_rx_csum_gbeth(priv->rx_1st_skb);
-				stats->rx_bytes += priv->rx_1st_skb->len;
-				napi_gro_receive(&priv->napi[q],
-						 priv->rx_1st_skb);
+					ravb_rx_csum_gbeth(skb);
+				stats->rx_bytes += skb->len;
+				napi_gro_receive(&priv->napi[q], skb);
 				rx_packets++;
-				break;
 			}
 		}
 	}