From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=55096 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PAnKQ-0004Lt-Cw for qemu-devel@nongnu.org; Tue, 26 Oct 2010 13:28:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PAnKP-00031K-E5 for qemu-devel@nongnu.org; Tue, 26 Oct 2010 13:28:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:61666) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PAnKP-00031E-2U for qemu-devel@nongnu.org; Tue, 26 Oct 2010 13:28:53 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o9QHSqwa012403 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 26 Oct 2010 13:28:52 -0400 Date: Tue, 26 Oct 2010 19:22:14 +0200 From: "Michael S. Tsirkin" Message-ID: <20101026172213.GA16645@redhat.com> References: <20101026164351.12358.73838.stgit@localhost6.localdomain6> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101026164351.12358.73838.stgit@localhost6.localdomain6> Subject: [Qemu-devel] Re: [PATCH] vhost-net: Do not set features for backend when peer was deleted List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jason Wang Cc: qemu-devel@nongnu.org On Wed, Oct 27, 2010 at 12:43:51AM +0800, Jason Wang wrote: > When hot-unplug a virtio nic with vhost-net backend, guest may > continue to program the nic even if its peer have been deleted. We can > not set features at this time as vhost_net_ack_features() may still > try to use the tap related vhost_net structure which have been freed > in tap_cleanup(). And setting offload features for a deleted backend > is also meaningless in this situation > > Signed-off-by: Jason Wang Hmm. Actually, this is not enough. We really must stop and cleanup vhost net. Two issues are 1. vhost_net_stop needs virtio device pointer 2. virtio net has a vhost_started flag Two ways to fix it that I see: 1. add a callback in nic and invoke when peer_deleted is set 2. add vhost_started and virtio device pointers in vhost Path 1 seems easier ... MST > --- > hw/virtio-net.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/hw/virtio-net.c b/hw/virtio-net.c > index 7e1688c..68c8e48 100644 > --- a/hw/virtio-net.c > +++ b/hw/virtio-net.c > @@ -245,6 +245,9 @@ static void virtio_net_set_features(VirtIODevice *vdev, uint32_t features) > { > VirtIONet *n = to_virtio_net(vdev); > > + if (n->nic->peer_deleted) > + return; > + > n->mergeable_rx_bufs = !!(features & (1 << VIRTIO_NET_F_MRG_RXBUF)); > > if (n->has_vnet_hdr) {