On Wed, 7 Sep 2016 11:51:25 -0400 Stefan Hajnoczi <stefa...@redhat.com> wrote:
> vq->inuse must be zeroed upon device reset like most other virtqueue > fields. > > In theory, virtio_reset() just needs assert(vq->inuse == 0) since > devices must clean up in-flight requests during reset (requests cannot > not be leaked!). > > In practice, it is difficult to achieve vq->inuse == 0 across reset > because balloon, blk, 9p, etc implement various different strategies for > cleaning up requests. Most devices call g_free(elem) directly without > telling virtio.c that the VirtQueueElement is cleaned up. Therefore > vq->inuse is not decremented during reset. > > This patch zeroes vq->inuse and trusts that devices are not leaking > VirtQueueElements across reset. > > I will send a follow-up series that refactors request life-cycle across > all devices and converts vq->inuse = 0 into assert(vq->inuse == 0) but > this more invasive approach is not appropriate for stable trees. > > Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> > --- > hw/virtio/virtio.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > index 74c085c..e8a13a5 100644 > --- a/hw/virtio/virtio.c > +++ b/hw/virtio/virtio.c > @@ -822,6 +822,7 @@ void virtio_reset(void *opaque) > vdev->vq[i].signalled_used_valid = false; > vdev->vq[i].notification = true; > vdev->vq[i].vring.num = vdev->vq[i].vring.num_default; > + vdev->vq[i].inuse = 0; > } > } > This looks sane as a minimal change, and survives my smoketests. Reviewed-by: Cornelia Huck <cornelia.h...@de.ibm.com>
