From patchwork Tue Nov 20 14:46:38 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [1/1] tap: reset vnet header size on open Date: Tue, 20 Nov 2012 04:46:38 -0000 From: Stefan Hajnoczi X-Patchwork-Id: 200363 Message-Id: <1353422798-30741-2-git-send-email-stefanha@redhat.com> To: Anthony Liguori Cc: qemu-devel@nongnu.org, Stefan Hajnoczi , "Michael S. Tsirkin" From: "Michael S. Tsirkin" 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 Tested-by: Alexander Graf Signed-off-by: Stefan Hajnoczi --- 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;