From mboxrd@z Thu Jan  1 00:00:00 1970
From: Zoltan Kiss <zoltan.kiss@citrix.com>
Subject: Re: [PATCH] openvswitch: orphan frags on local receive
Date: Mon, 24 Feb 2014 14:45:00 +0000
Message-ID: <530B5AEC.5020509@citrix.com>
References: <530B45E0.20009@huawei.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="ISO-8859-1"; format=flowed
Content-Transfer-Encoding: 7bit
Cc: KVM list <kvm@vger.kernel.org>, <netdev@vger.kernel.org>
To: Qin Chuanyu <qinchuanyu@huawei.com>, <davem@davemloft.net>,
	"Michael S. Tsirkin" <mst@redhat.com>
Return-path: <kvm-owner@vger.kernel.org>
In-Reply-To: <530B45E0.20009@huawei.com>
Sender: kvm-owner@vger.kernel.org
List-Id: netdev.vger.kernel.org

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 <qinchuanyu@huawei.com>
> ---
>  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);