net: stmmac: Check for DMA mapping errors

When DMA mapping an SKB fragment, the mapping must be checked for
errors, otherwise the DMA debug code will complain upon unmap.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -2079,6 +2079,8 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)
 		des = skb_frag_dma_map(priv->device, frag, 0,
 				       skb_frag_size(frag),
 				       DMA_TO_DEVICE);
+		if (dma_mapping_error(priv->device, des))
+			goto dma_map_err;
 
 		stmmac_tso_allocator(priv, des, skb_frag_size(frag),
 				     (i == nfrags - 1));