From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34286) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aVa2c-0003ks-Cc for qemu-devel@nongnu.org; Tue, 16 Feb 2016 02:27:53 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aVa1m-0001XQ-5Y for qemu-devel@nongnu.org; Tue, 16 Feb 2016 02:27:22 -0500 Received: from mx1.redhat.com ([209.132.183.28]:43718) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aVa1l-0001Vk-Vu for qemu-devel@nongnu.org; Tue, 16 Feb 2016 02:26:30 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id 254B18E3F2 for ; Tue, 16 Feb 2016 07:26:29 +0000 (UTC) Date: Tue, 16 Feb 2016 15:26:26 +0800 From: Fam Zheng Message-ID: <20160216072626.GM18664@ad.usersys.redhat.com> References: <1455470231-5223-1-git-send-email-pbonzini@redhat.com> <1455470231-5223-6-git-send-email-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1455470231-5223-6-git-send-email-pbonzini@redhat.com> Subject: Re: [Qemu-devel] [PATCH 5/8] virtio-blk: fix "disabled data plane" mode List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: qemu-devel@nongnu.org, stefanha@redhat.com, mst@redhat.com On Sun, 02/14 18:17, Paolo Bonzini wrote: > In disabled mode, virtio-blk dataplane seems to be enabled, but flow > actually goes through the normal virtio path. This patch simplifies a bit > the handling of disabled mode. In disabled mode, virtio_blk_handle_output > might be called even if s->dataplane is not NULL. > > This is a bit tricky, because the current check for s->dataplane will > always trigger, causing a continuous stream of calls to > virtio_blk_data_plane_start. Unfortunately, these calls will not > do anything. To fix this, set the "started" flag even in disabled > mode, and skip virtio_blk_data_plane_start if the started flag is true. > The resulting changes also prepare the code for the next patch, were > virtio-blk dataplane will reuse the same virtio_blk_handle_output function > as "regular" virtio-blk. > > Because struct VirtIOBlockDataPlane is opaque in virtio-blk.c, we have > to move s->dataplane->started inside struct VirtIOBlock. > > Signed-off-by: Paolo Bonzini > --- > hw/block/dataplane/virtio-blk.c | 21 +++++++++------------ > hw/block/virtio-blk.c | 2 +- > include/hw/virtio/virtio-blk.h | 1 + > 3 files changed, 11 insertions(+), 13 deletions(-) > > diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c > index 03b81bc..cc521c1 100644 > --- a/hw/block/dataplane/virtio-blk.c > +++ b/hw/block/dataplane/virtio-blk.c > @@ -28,7 +28,6 @@ > #include "qom/object_interfaces.h" > > struct VirtIOBlockDataPlane { > - bool started; > bool starting; > bool stopping; > bool disabled; > @@ -264,11 +263,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s) > VirtQueue *vq; > int r; > > - if (s->started || s->disabled) { > - return; > - } > - > - if (s->starting) { > + if (vblk->dataplane_started || s->starting) { > return; > } > > @@ -300,7 +295,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s) > vblk->complete_request = complete_request_vring; > > s->starting = false; > - s->started = true; > + vblk->dataplane_started = true; > trace_virtio_blk_data_plane_start(s); > > blk_set_aio_context(s->conf->conf.blk, s->ctx); > @@ -319,9 +314,10 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s) > k->set_guest_notifiers(qbus->parent, 1, false); > fail_guest_notifiers: > vring_teardown(&s->vring, s->vdev, 0); > - s->disabled = true; > fail_vring: > + s->disabled = true; > s->starting = false; Worth a comment here, or at definition of dataplane_started, explaining the trick said in the commit message? Reviewed-by: Fam Zheng > + vblk->dataplane_started = true; > } > <...>