On Wed, Sep 7, 2016 at 5:54 PM, Stefan Hajnoczi <stefa...@gmail.com> wrote: > On Wed, Sep 7, 2016 at 11:51 AM, 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; >> } >> } >> >> -- >> 2.7.4 > > CCing qemu-stable
Reviewed-by: Ladi Prosek <lpro...@redhat.com>