vhost_kernel_reset_device() invokes RESET_OWNER, which disassociates the
owner process from the device. The device is left non-operational since
SET_OWNER is only called once during startup in vhost_dev_init().

vhost_kernel_reset_device() is never called so this latent bug never
appears. Get rid of vhost_kernel_reset_device() for now. If someone
needs it in the future they'll need to implement it correctly.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 hw/virtio/vhost-backend.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
index 8e581575c9..17f3fc6a08 100644
--- a/hw/virtio/vhost-backend.c
+++ b/hw/virtio/vhost-backend.c
@@ -197,11 +197,6 @@ static int vhost_kernel_set_owner(struct vhost_dev *dev)
     return vhost_kernel_call(dev, VHOST_SET_OWNER, NULL);
 }
 
-static int vhost_kernel_reset_device(struct vhost_dev *dev)
-{
-    return vhost_kernel_call(dev, VHOST_RESET_OWNER, NULL);
-}
-
 static int vhost_kernel_get_vq_index(struct vhost_dev *dev, int idx)
 {
     assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs);
@@ -322,7 +317,6 @@ const VhostOps kernel_ops = {
         .vhost_get_features = vhost_kernel_get_features,
         .vhost_set_backend_cap = vhost_kernel_set_backend_cap,
         .vhost_set_owner = vhost_kernel_set_owner,
-        .vhost_reset_device = vhost_kernel_reset_device,
         .vhost_get_vq_index = vhost_kernel_get_vq_index,
         .vhost_vsock_set_guest_cid = vhost_kernel_vsock_set_guest_cid,
         .vhost_vsock_set_running = vhost_kernel_vsock_set_running,
-- 
2.41.0

On 04.10.23 03:45, Stefan Hajnoczi wrote:
> vhost_kernel_reset_device() invokes RESET_OWNER, which disassociates the
> owner process from the device. The device is left non-operational since
> SET_OWNER is only called once during startup in vhost_dev_init().
>
> vhost_kernel_reset_device() is never called so this latent bug never
> appears. Get rid of vhost_kernel_reset_device() for now. If someone
> needs it in the future they'll need to implement it correctly.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>   hw/virtio/vhost-backend.c | 6 ------
>   1 file changed, 6 deletions(-)

The obvious way would be to immediately call SET_OWNER again, but I 
assume that just like in vhost-user, it is probably pretty much left 
undefined what exactly should happen in the back-end on RESET_OWNER, and 
so I agree that in general, starting to call this function now when we 
didn’t before is more of a liability then anything.

Reviewed-by: Hanna Czenczek <hreitz@redhat.com>