[patch 02/41] ixgb: fix bug when freeing resources

[Greg KH <gregkh@suse.de>]

[-- Attachment #1: ixgb-fix-bug-when-freeing-resources.patch --]
[-- Type: text/plain, Size: 1406 bytes --]

2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Brandeburg, Jesse <jesse.brandeburg@intel.com>

commit 23e55a32ca1ffdbe7a492ef99f0e0ac48e504a13 upstream.

It was pointed out by Breno Leitao <leitao@linux.vnet.ibm.com> that
ixgb would crash on PPC when an IOMMU was in use, if change_mtu was
called.

It appears to be a pretty simple issue in the driver that wasn't discovered
because most systems don't run with an IOMMU.  The driver needs to only unmap
buffers that are mapped (duh).

CC: Breno Leitao <leitao@linux.vnet.ibm.com>

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/net/ixgb/ixgb_main.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/net/ixgb/ixgb_main.c
+++ b/drivers/net/ixgb/ixgb_main.c
@@ -977,15 +977,17 @@ ixgb_clean_rx_ring(struct ixgb_adapter *
 
 	for (i = 0; i < rx_ring->count; i++) {
 		buffer_info = &rx_ring->buffer_info[i];
-		if (buffer_info->skb) {
-
+		if (buffer_info->dma) {
 			pci_unmap_single(pdev,
 					 buffer_info->dma,
 					 buffer_info->length,
 					 PCI_DMA_FROMDEVICE);
+			buffer_info->dma = 0;
+			buffer_info->length = 0;
+		}
 
+		if (buffer_info->skb) {
 			dev_kfree_skb(buffer_info->skb);
-
 			buffer_info->skb = NULL;
 		}
 	}