From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH] virtio_net: return error when there is no virtqueue or MQ isn't support Date: Tue, 22 Apr 2014 11:53:34 +0800 Message-ID: <5355E7BE.10506@redhat.com> References: <1398093061-13444-1-git-send-email-akong@redhat.com> <5355DDF6.7050509@redhat.com> <20140422032351.GA2543@amosk.info> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, mst@redhat.com, virtualization@lists.linux-foundation.org To: Amos Kong Return-path: In-Reply-To: <20140422032351.GA2543@amosk.info> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org On 04/22/2014 11:23 AM, Amos Kong wrote: > On Tue, Apr 22, 2014 at 11:11:50AM +0800, Jason Wang wrote: >> On 04/21/2014 11:11 PM, Amos Kong wrote: >>> Currently ethtool returns zero if there is no virtqueue or MQ isn't >>> support, we should return -ENOTSUPP to notice user. >>> >>> Signed-off-by: Amos Kong >>> --- >>> drivers/net/virtio_net.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >>> index 8a852b5..eaf8266 100644 >>> --- a/drivers/net/virtio_net.c >>> +++ b/drivers/net/virtio_net.c >>> @@ -1053,7 +1053,7 @@ static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs) >>> struct net_device *dev = vi->dev; >>> >>> if (!vi->has_cvq || !virtio_has_feature(vi->vdev, VIRTIO_NET_F_MQ)) >>> - return 0; >>> + return -ENOTSUPP; >>> >>> s.virtqueue_pairs = queue_pairs; >>> sg_init_one(&sg, &s, sizeof(s)); >> How about check the return value of virtnet_set_queues() in >> virtnet_restore() also? > If we migrate a guest from MQ supported side to MQ non-supported side, > virtnet_restore() will not return error right now. > > If we return error when no vq or no mq support, and check return value > of virtnet_set_queues() in virtnet_restore(), migration will fail. > Is it expected? > > I think what you mean is restore not migration here. The point is not to execute VIRTIO_NET_CTRL_MQ when multiqueue is not supported, so it's the caller responsibility to pass a valid queue_pairs to virtnet_set_queues(). This patch is not necessary, your last patch is fine enough to solve the issue. Do you agree? Thanks