ibmveth: fix bad UDP checksums (45e15bb7) · Commits · 戴 / test

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>

drivers/net/ibmveth.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -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;

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