Re: [REGRESSION][BISECTED] skge: add dma_mapping check

[Francois Romieu <romieu@fr.zoreil.com>]

Igor Gnatenko <i.gnatenko.brain@gmail.com> :
> Since 136d8f377e1575463b47840bc5f1b22d94bf8f63 commit we have kernel
> panic on:
> 01:05.0 Ethernet controller [0200]: Marvell Technology Group Ltd.
> 
> Screen: https://www.dropbox.com/s/mu3t3wxpxbn4ou5/IMAG0507.jpg
> 
> RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1008323

Does the ugly stuff below against mainline make a difference ?

Note to testers: use a size argument above 500 for 'ping' to
exercize the relevant code path.

diff --git a/drivers/net/ethernet/marvell/skge.c b/drivers/net/ethernet/marvell/skge.c
index ef94a59..aa85a3f 100644
--- a/drivers/net/ethernet/marvell/skge.c
+++ b/drivers/net/ethernet/marvell/skge.c
@@ -3086,6 +3086,7 @@ static struct sk_buff *skge_rx_get(struct net_device *dev,
 					       PCI_DMA_FROMDEVICE);
 		skge_rx_reuse(e, skge->rx_buf_size);
 	} else {
+		struct skge_element ee = *e;
 		struct sk_buff *nskb;
 
 		nskb = netdev_alloc_skb_ip_align(dev, skge->rx_buf_size);
@@ -3098,10 +3099,10 @@ static struct sk_buff *skge_rx_get(struct net_device *dev,
 		}
 
 		pci_unmap_single(skge->hw->pdev,
-				 dma_unmap_addr(e, mapaddr),
-				 dma_unmap_len(e, maplen),
+				 dma_unmap_addr(&ee, mapaddr),
+				 dma_unmap_len(&ee, maplen),
 				 PCI_DMA_FROMDEVICE);
-		skb = e->skb;
+		skb = ee.skb;
 		prefetch(skb->data);
 	}