On Tue, 2013-03-26 at 06:19 +0000, Jason Wang wrote:
> Currently, for the packets receives from netback, before doing header check,
> kernel just reset the transport header in netif_receive_skb() which pretends
> non
> l4 header. This is suboptimal for precise packet length estimation (introduced
> in 1def9238: net_sched: more precise pkt_len computation) which needs correct
> l4
> header for gso packets.
>
> The patch just reuse the header probed by netback for partial checksum packets
> and tries to use skb_flow_dissect() for other cases, if both fail, just
> pretend
> no l4 header.
>
> Cc: Eric Dumazet <eduma...@google.com>
> Cc: Ian Campbell <ian.campb...@citrix.com>
> Signed-off-by: Jason Wang <jasow...@redhat.com>
> ---
> drivers/net/xen-netback/netback.c | 12 ++++++++++++
> 1 files changed, 12 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/net/xen-netback/netback.c
> b/drivers/net/xen-netback/netback.c
> index aa28550..fc8faa7 100644
> --- a/drivers/net/xen-netback/netback.c
> +++ b/drivers/net/xen-netback/netback.c
> @@ -39,6 +39,7 @@
> #include <linux/udp.h>
>
> #include <net/tcp.h>
> +#include <net/flow_keys.h>
>
> #include <xen/xen.h>
> #include <xen/events.h>
> @@ -1184,6 +1185,7 @@ static int checksum_setup(struct xenvif *vif, struct
> sk_buff *skb)
> if (th >= skb_tail_pointer(skb))
> goto out;
>
> + skb_set_transport_header(skb, 4 * iph->ihl);
> skb->csum_start = th - skb->head;
Should the use of th here (and perhaps above) be replaced with
skb_transport_header() too?
> switch (iph->protocol) {
> case IPPROTO_TCP:
> @@ -1495,6 +1497,7 @@ static void xen_netbk_tx_submit(struct xen_netbk *netbk)
>
> skb->dev = vif->dev;
> skb->protocol = eth_type_trans(skb, skb->dev);
> + skb_reset_network_header(skb);
>
> if (checksum_setup(vif, skb)) {
> netdev_dbg(vif->dev,
> @@ -1503,6 +1506,15 @@ static void xen_netbk_tx_submit(struct xen_netbk
> *netbk)
> continue;
> }
>
> + if (!skb_transport_header_was_set(skb)) {
> + struct flow_keys keys;
> +
> + if (skb_flow_dissect(skb, &keys))
> + skb_set_transport_header(skb, keys.thoff);
> + else
> + skb_reset_transport_header(skb);
> + }
> +
> vif->dev->stats.rx_bytes += skb->len;
> vif->dev->stats.rx_packets++;
>
--
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