From: Rusty Russell <rusty@rustcorp.com.au>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>, netdev@vger.kernel.org
Subject: Re: virtio_net: Set correct gso->hdr_len
Date: Fri, 5 Jun 2009 13:51:05 +0930 [thread overview]
Message-ID: <200906051351.06385.rusty@rustcorp.com.au> (raw)
In-Reply-To: <20090604105917.GA28273@gondor.apana.org.au>
On Thu, 4 Jun 2009 08:29:18 pm Herbert Xu wrote:
> Hi:
>
> virtio_net: Set correct gso->hdr_len
>
> Through a bug in the tun driver, I noticed that virtio_net is
> producing bogus hdr_len values. In particular, it only includes
> the IP header in the linear area, and excludes the entire TCP
> header. This causes the TCP header to be copied twice for each
> packet. (The bug omitted the second copy :)
>
> This patch corrects this.
>
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 4d1d479..1c9cedd 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -470,7 +470,7 @@ static int xmit_skb(struct virtnet_info *vi, struct
> sk_buff *skb) }
>
> if (skb_is_gso(skb)) {
> - hdr->hdr_len = skb_transport_header(skb) - skb->data;
> + hdr->hdr_len = skb_headlen(skb);
Ouch!
But are we allowed to make the assumption that skb_headlen() ==
skb_transport_header(skb) + sizeof(transport header) ? Or should we be
checking that here?
Also how did this ever work? Why are we getting packets through at all?
Damn, I'm away from my test boxes an I really want to benchmark this fix.
Rusty.
next prev parent reply other threads:[~2009-06-05 4:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-04 10:59 virtio_net: Set correct gso->hdr_len Herbert Xu
2009-06-05 4:21 ` Rusty Russell [this message]
2009-06-05 4:27 ` Herbert Xu
2009-06-05 6:50 ` Rusty Russell
2009-06-05 6:53 ` Herbert Xu
2009-06-08 7:22 ` David Miller
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