From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH] bridge: orphan frags on local receive Date: Mon, 24 Feb 2014 17:49:21 +0200 Message-ID: <20140224154921.GH8981@redhat.com> References: <530B4534.3000106@huawei.com> <20140224132926.GF8981@redhat.com> <530B4E8B.5050007@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: davem@davemloft.net, KVM list , netdev@vger.kernel.org To: Qin Chuanyu Return-path: Content-Disposition: inline In-Reply-To: <530B4E8B.5050007@huawei.com> Sender: kvm-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Mon, Feb 24, 2014 at 09:52:11PM +0800, Qin Chuanyu wrote: > On 2014/2/24 21:29, Michael S. Tsirkin wrote: > >On Mon, Feb 24, 2014 at 09:12:20PM +0800, 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 bridge. This could easily happened when a > >>LAST_ACK state tcp occuring between guest and host. > >> > >>Signed-off-by: Chuanyu Qin > > > >Do you actually observe guest hang? > > > yes, guest nic could not xmit any more until the skb holded by host has > been freed, the mainly reason is that though virtio-net could use vring > desc out of order, but ubufs is been used by vhost in order. so only > one skb could cause guest nic hang. > >I would expect orphan frags in > >__netif_receive_skb_core to be enough. > > > yes, it would be better. I would deliver another patch soon. well __netif_receive_skb_core already calls orphan frags already. What's left to do? > > > >>--- > >> net/bridge/br_input.c | 3 +++ > >> 1 files changed, 3 insertions(+), 0 deletions(-) > >> > >>diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c > >>index 28d5446..744e27a 100644 > >>--- a/net/bridge/br_input.c > >>+++ b/net/bridge/br_input.c > >>@@ -117,6 +117,8 @@ int br_handle_frame_finish(struct sk_buff *skb) > >> br->dev->stats.multicast++; > >> } else if ((dst = __br_fdb_get(br, dest, vid)) && > >> dst->is_local) { > >>+ if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC))) > >>+ goto drop; > >> skb2 = skb; > >> /* Do not forward the packet since it's local. */ > >> skb = NULL; > >>@@ -136,6 +138,7 @@ int br_handle_frame_finish(struct sk_buff *skb) > >> out: > >> return 0; > >> drop: > >>+ skb_tx_error(skb); > >> kfree_skb(skb); > >> goto out; > >> } > >>-- > >>1.7.3.1.msysgit.0 > > > > >