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ibmveth: fix bad UDP checksums

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This patch fixes a ibmveth bug where bad UDP checksums are being transmitted
when checksum offloading is enabled.
The hypervisor does checksum offloading only on TCP packets, so ibmveth calls
skb_checksum_help() for any other protocol.  The bug happens because
the packet is being modified after the DMA map, so we would need a memory
barrier before making the hypervisor call.  Reordering the code so that the
DMA map happens after skb_checksum_help() has the additional advantage of
fixing a DMA map leak if skb_checksum_help() where to fail.

Signed-off-by: Santiago Leon <santil@us.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
This commit is contained in:
Santiago Leon 2008-08-20 13:09:19 -06:00 committed by Jeff Garzik
parent c213f286f2
commit 45e15bb734
1 changed files with 3 additions and 2 deletions
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5
drivers/net/ibmveth.c
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@ -904,8 +904,6 @@ static int ibmveth_start_xmit(struct sk_buff *skb, struct net_device *netdev)
unsigned long data_dma_addr;
desc.fields.flags_len = IBMVETH_BUF_VALID | skb->len;
data_dma_addr = dma_map_single(&adapter->vdev->dev, skb->data,
skb->len, DMA_TO_DEVICE);
if (skb->ip_summed == CHECKSUM_PARTIAL &&
ip_hdr(skb)->protocol != IPPROTO_TCP && skb_checksum_help(skb)) {
@ -924,6 +922,8 @@ static int ibmveth_start_xmit(struct sk_buff *skb, struct net_device *netdev)
buf[1] = 0;
}
data_dma_addr = dma_map_single(&adapter->vdev->dev, skb->data,
skb->len, DMA_TO_DEVICE);
if (dma_mapping_error(&adapter->vdev->dev, data_dma_addr)) {
if (!firmware_has_feature(FW_FEATURE_CMO))
ibmveth_error_printk("tx: unable to map xmit buffer\n");
@ -932,6 +932,7 @@ static int ibmveth_start_xmit(struct sk_buff *skb, struct net_device *netdev)
desc.fields.address = adapter->bounce_buffer_dma;
tx_map_failed++;
used_bounce = 1;
wmb();
} else
desc.fields.address = data_dma_addr;