From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zoltan Kiss Subject: Re: [PATCH] openvswitch: Orphan frags before sending to userspace via Netlink to avoid guest stall Date: Thu, 6 Mar 2014 17:09:20 +0000 Message-ID: <5318ABC0.4040307@citrix.com> References: <1393615016-9187-1-git-send-email-zoltan.kiss@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Cc: , , , To: Jesse Gross , , , Return-path: In-Reply-To: <1393615016-9187-1-git-send-email-zoltan.kiss@citrix.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Do you have any feedback on this? I'm also adding KVM list as they might be interested in this. Zoli On 28/02/14 19:16, Zoltan Kiss wrote: > The kernel datapath now switched to zerocopy Netlink messages, but that also > means that the pages on frags array are sent straight to userspace. If those > pages came outside the kernel, we have to swap them out with local copies. > > Signed-off-by: Zoltan Kiss > --- > net/openvswitch/datapath.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c > index 36f8872..ffb563c 100644 > --- a/net/openvswitch/datapath.c > +++ b/net/openvswitch/datapath.c > @@ -464,6 +464,12 @@ static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb, > } > nla->nla_len = nla_attr_size(skb->len); > > + if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC))) { > + err = -ENOMEM; > + skb_tx_error(skb); > + goto out; > + } > + > skb_zerocopy(user_skb, skb, skb->len, hlen); > > /* Pad OVS_PACKET_ATTR_PACKET if linear copy was performed */ >