Subject: [PATCH] net: ethernet: mtk_eth_soc: unmap rx data before calling build_skb
From: Felix Fietkau <[email-masked]>
Date: Thu, 27 Aug 2020 09:44:43 +0200

Since build_skb accesses the data area (for initializing shinfo), dma unmap
needs to happen before that call

Signed-off-by: Felix Fietkau <[email-masked]>
---

--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -1293,17 +1293,18 @@ static int mtk_poll_rx(struct napi_struc
 			goto release_desc;
 		}
 
+		dma_unmap_single(eth->dev, trxd.rxd1,
+				 ring->buf_size, DMA_FROM_DEVICE);
+
 		/* receive data */
 		skb = build_skb(data, ring->frag_size);
 		if (unlikely(!skb)) {
-			skb_free_frag(new_data);
+			skb_free_frag(data);
 			netdev->stats.rx_dropped++;
-			goto release_desc;
+			goto skip_rx;
 		}
 		skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
 
-		dma_unmap_single(eth->dev, trxd.rxd1,
-				 ring->buf_size, DMA_FROM_DEVICE);
 		pktlen = RX_DMA_GET_PLEN0(trxd.rxd2);
 		skb->dev = netdev;
 		skb_put(skb, pktlen);
@@ -1321,6 +1322,7 @@ static int mtk_poll_rx(struct napi_struc
 		skb_record_rx_queue(skb, 0);
 		napi_gro_receive(napi, skb);
 
+skip_rx:
 		ring->data[idx] = new_data;
 		rxd->rxd1 = (unsigned int)dma_addr;