From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:44706) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TYDbx-0002uK-44 for qemu-devel@nongnu.org; Tue, 13 Nov 2012 05:20:56 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TYDbu-0004op-2O for qemu-devel@nongnu.org; Tue, 13 Nov 2012 05:20:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57068) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TYDbt-0004oc-Ii for qemu-devel@nongnu.org; Tue, 13 Nov 2012 05:20:49 -0500 Date: Tue, 13 Nov 2012 12:23:23 +0200 From: "Michael S. Tsirkin" Message-ID: <20121113102323.GA29422@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Subject: [Qemu-devel] [PATCHv2] tap: reset vnet header size on open List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, agraf@suse.de Cc: Anthony Liguori , Stefan Hajnoczi For tap, we currently assume the vnet header size is 10 (the default value) but that might not be the case if tap is persistent and has been used by qemu previously. To fix, set host header size in tap device on open. Signed-off-by: Michael S. Tsirkin --- This fixes the issue reported by Alexander Graf on the kvm forum. Alexander, could you confirm please? Thanks, net/tap.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/tap.c b/net/tap.c index df89caa..1abfd44 100644 --- a/net/tap.c +++ b/net/tap.c @@ -341,6 +341,13 @@ static TAPState *net_tap_fd_init(NetClientState *peer, s->using_vnet_hdr = 0; s->has_ufo = tap_probe_has_ufo(s->fd); tap_set_offload(&s->nc, 0, 0, 0, 0, 0); + /* + * Make sure host header length is set correctly in tap: + * it might have been modified by another instance of qemu. + */ + if (tap_probe_vnet_hdr_len(s->fd, s->host_vnet_hdr_len)) { + tap_fd_set_vnet_hdr_len(s->fd, s->host_vnet_hdr_len); + } tap_read_poll(s, 1); s->vhost_net = NULL; return s; -- MST