vhost-net: update used ring on backend change

On backend change, we flushed out outstanding skbs but forgot to update the used ring, so that done entries were left in the ubuf_info ring. As a result we lose heads or complete incorrect ones, crashing the guest or leaking memory. Fix by updating the used ring. Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

vhost-net: update used ring on backend change
On backend change, we flushed out outstanding skbs but forgot to update the used ring, so that done entries were left in the ubuf_info ring. As a result we lose heads or complete incorrect ones, crashing the guest or leaking memory. Fix by updating the used ring. Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Michael S. Tsirkin
1 parent b834226b04
Showing 1 changed file with 5 additions and 1 deletions Side-by-side Diff
drivers/vhost/net.c
@@ -711,8 +711,12 @@
  
 	mutex_unlock(&vq->mutex);
  
-	if (oldubufs)
+	if (oldubufs) {
 		vhost_ubuf_put_and_wait(oldubufs);
+		mutex_lock(&vq->mutex);
+		vhost_zerocopy_signal_used(vq);
+		mutex_unlock(&vq->mutex);
+	}
  
 	if (oldsock) {
 		vhost_net_flush_vq(n, index);
...	...	@@ -711,8 +711,12 @@
711	711
712	712	mutex_unlock(&vq->mutex);
713	713
714		- if (oldubufs)
	714	+ if (oldubufs) {
715	715	vhost_ubuf_put_and_wait(oldubufs);
	716	+ mutex_lock(&vq->mutex);
	717	+ vhost_zerocopy_signal_used(vq);
	718	+ mutex_unlock(&vq->mutex);
	719	+ }
716	720
717	721	if (oldsock) {
718	722	vhost_net_flush_vq(n, index);