[Saucy][PATCH 1/1] skge: fix broken driver

[Joseph Salisbury]

From: Mikulas Patocka <mpatocka at redhat.com>

BugLink: http://bugs.launchpad.net/bugs/1216745

The patch 136d8f377e1575463b47840bc5f1b22d94bf8f63 broke the skge driver.
Note this part of the patch:
+               if (skge_rx_setup(skge, e, nskb, skge->rx_buf_size) < 0) {
+                       dev_kfree_skb(nskb);
+                       goto resubmit;
+               }
+
                pci_unmap_single(skge->hw->pdev,
                                 dma_unmap_addr(e, mapaddr),
                                 dma_unmap_len(e, maplen),
                                 PCI_DMA_FROMDEVICE);
                skb = e->skb;
                prefetch(skb->data);
-               skge_rx_setup(skge, e, nskb, skge->rx_buf_size);

The function skge_rx_setup modifies e->skb to point to the new skb. Thus,
after this change, the new buffer, not the old, is returned to the
networking stack.

This bug is present in kernels 3.11, 3.11.1 and 3.12-rc1. The patch should
be queued for 3.11-stable.

Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
Reported-by: Mikulas Patocka <mpatocka at redhat.com>
Reported-by: Vasiliy Glazov <vascom2 at gmail.com>
Tested-by: Mikulas Patocka <mpatocka at redhat.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
(cherry picked from commit c194992cbe71c20bb3623a566af8d11b0bfaa721)

Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>

---
 drivers/net/ethernet/marvell/skge.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/marvell/skge.c b/drivers/net/ethernet/marvell/skge.c
index ef94a59..1a9c4f6 100644
--- a/drivers/net/ethernet/marvell/skge.c
+++ b/drivers/net/ethernet/marvell/skge.c
@@ -3092,6 +3092,9 @@ static struct sk_buff *skge_rx_get(struct net_device *dev,
 		if (!nskb)
 			goto resubmit;
 
+		skb = e->skb;
+		prefetch(skb->data);
+
 		if (skge_rx_setup(skge, e, nskb, skge->rx_buf_size) < 0) {
 			dev_kfree_skb(nskb);
 			goto resubmit;
@@ -3101,8 +3104,6 @@ static struct sk_buff *skge_rx_get(struct net_device *dev,
 				 dma_unmap_addr(e, mapaddr),
 				 dma_unmap_len(e, maplen),
 				 PCI_DMA_FROMDEVICE);
-		skb = e->skb;
-		prefetch(skb->data);
 	}
 
 	skb_put(skb, len);
-- 
1.7.9.5