Subject: tun: Fix csum_start computation Date: Fri, 13 Jun 2008 14:27:37 +0100 From: Mark McLoughlin virtio_net_hdr's csum_start is relative to the start of the ethernet header. skb.csum_start is relative to skb->head. In skb_partial_csum set() we add the headroom to the supplied csum_start to get skb->head. However, when tun.c:xmit_packets() gets around to calling it, the ethernet head has been pulled into the skb headroom. Therefore we need to supply a csum_start which is relative to the IP header. (Fixes misc:tun-xmit-vring.patch) Signed-off-by: Mark McLoughlin Signed-off-by: Rusty Russell --- drivers/net/tun.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 2d0c16a..75362ce 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -642,7 +642,7 @@ static int xmit_packets(void *_tun) return PTR_ERR(skb); if ((h.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) && - !skb_partial_csum_set(skb, h.csum_start, h.csum_offset)) { + !skb_partial_csum_set(skb, h.csum_start - ETH_HLEN, h.csum_offset)) { kfree_skb(skb); return -EINVAL; }