Subject: Re: [PATCH] openvswitch: orphan frags on local receive

From: Zoltan Kiss <[email-masked]>
Date: Mon, 24 Feb 2014 14:45:00 +0000

Hi,

I'm also planning a similar patch, but it will call skb_orphan_frags on 
the skb in datapath.c::queue_userspace_packet, right before 
skb_zerocopy, so packets sent up to userspace via Netlink doesn't harm 
guests. I haven't checked your patch thoroughly, does it handle a 
different scenario?

Regards,

Zoltan Kiss

On 24/02/14 13:15, Qin Chuanyu wrote:
> with vhost tx zero_copy, guest nic might get hang when host reserving
> skb in socket queue delivered by guest, the case has been solved in
> tun, it also been needed by openvswitch. This could easily happened
> when a LAST_ACK state tcp occuring between guest and host.
>
> Signed-off-by: Chuanyu Qin <[email-masked]>
> ---
>  net/openvswitch/vport-internal_dev.c |    3 +++
>  net/openvswitch/vport.c              |    1 +
>  2 files changed, 4 insertions(+), 0 deletions(-)
>
> diff --git a/net/openvswitch/vport-internal_dev.c 
> b/net/openvswitch/vport-internal_dev.c
> index 729c687..adb25e2 100644
> --- a/net/openvswitch/vport-internal_dev.c
> +++ b/net/openvswitch/vport-internal_dev.c
> @@ -212,6 +212,9 @@ static int internal_dev_recv(struct vport *vport, 
> struct sk_buff *skb)
>      struct net_device *netdev = netdev_vport_priv(vport)->dev;
>      int len;
>
> +    if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC)))
> +        return -NET_RX_DROP;
> +
>      len = skb->len;
>
>      skb_dst_drop(skb);
> diff --git a/net/openvswitch/vport.c b/net/openvswitch/vport.c
> index 208dd9a..04172d6 100644
> --- a/net/openvswitch/vport.c
> +++ b/net/openvswitch/vport.c
> @@ -383,6 +383,7 @@ int ovs_vport_send(struct vport *vport, struct 
> sk_buff *skb)
>          u64_stats_update_end(&stats->syncp);
>      } else if (sent < 0) {
>          ovs_vport_record_error(vport, VPORT_E_TX_ERROR);
> +        skb_tx_error(skb);
>          kfree_skb(skb);
>      } else
>          ovs_vport_record_error(vport, VPORT_E_TX_DROPPED);