From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35826) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gBxr7-0000lw-M6 for qemu-devel@nongnu.org; Mon, 15 Oct 2018 04:04:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gBxr6-0003rR-Ps for qemu-devel@nongnu.org; Mon, 15 Oct 2018 04:04:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35786) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gBxr6-0003rJ-JA for qemu-devel@nongnu.org; Mon, 15 Oct 2018 04:04:00 -0400 Date: Mon, 15 Oct 2018 16:03:43 +0800 From: Wei Xu Message-ID: <20181015080343.GE27871@wei-ubt> References: <1539266915-15216-1-git-send-email-wexu@redhat.com> <1539266915-15216-10-git-send-email-wexu@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [[RFC v3 09/12] virtio-net: fill head desc after done all in a chain List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jason Wang Cc: qemu-devel@nongnu.org, maxime.coquelin@redhat.com, jfreimann@redhat.com, tiwei.bie@intel.com On Mon, Oct 15, 2018 at 03:45:46PM +0800, Jason Wang wrote: >=20 >=20 > On 2018=E5=B9=B410=E6=9C=8811=E6=97=A5 22:08, wexu@redhat.com wrote: > >From: Wei Xu > > > >With the support of marking a descriptor used/unused in 'flags' > >field for 1.1, the current way of filling a chained descriptors > >does not work since driver side may get the wrong 'num_buffer' > >information in case of the head descriptor has been filled in > >while the subsequent ones are still in processing in device side. > > > >This patch fills the head one after done all the others one. > > > >Signed-off-by: Wei Xu > >--- > > hw/net/virtio-net.c | 11 ++++++++++- > > 1 file changed, 10 insertions(+), 1 deletion(-) > > > >diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c > >index 4bdd5b8..186c86cd2 100644 > >--- a/hw/net/virtio-net.c > >+++ b/hw/net/virtio-net.c > >@@ -1198,6 +1198,8 @@ static ssize_t virtio_net_receive_rcu(NetClientS= tate *nc, const uint8_t *buf, > > struct virtio_net_hdr_mrg_rxbuf mhdr; > > unsigned mhdr_cnt =3D 0; > > size_t offset, i, guest_offset; > >+ VirtQueueElement head; > >+ int head_len =3D 0; > > if (!virtio_net_can_receive(nc)) { > > return -1; > >@@ -1275,7 +1277,13 @@ static ssize_t virtio_net_receive_rcu(NetClient= State *nc, const uint8_t *buf, > > } > > /* signal other side */ > >- virtqueue_fill(q->rx_vq, elem, total, i++); > >+ if (i =3D=3D 0) { > >+ head_len =3D total; > >+ head =3D *elem; > >+ } else { > >+ virtqueue_fill(q->rx_vq, elem, len, i); > >+ } > >+ i++; > > g_free(elem); > > } > >@@ -1286,6 +1294,7 @@ static ssize_t virtio_net_receive_rcu(NetClientS= tate *nc, const uint8_t *buf, > > &mhdr.num_buffers, sizeof mhdr.num_buffers); > > } > >+ virtqueue_fill(q->rx_vq, &head, head_len, 0); >=20 > It's not a good idea to fix API in device implementation. Let's introdu= ce > new API and fix it there. >=20 > E.g virtqueue_fill_n() and update the flag of first elem at the last st= ep. OK, I haven't considered about the other devices so far. Wei >=20 > Thanks >=20 > > virtqueue_flush(q->rx_vq, i); > > virtio_notify(vdev, q->rx_vq); >=20 >=20