virtio-mem: detach the element from the virtqueue when error occurs

If error occurs while processing the virtio request we should call
'virtqueue_detach_element' to detach the element from the virtqueue
before free the elem.

Signed-off-by: Li Qiang <[email protected]>
Message-Id: <[email protected]>
Fixes: 910b257 ("virtio-mem: Paravirtualized memory hot(un)plug")
Acked-by: David Hildenbrand <[email protected]>
Reviewed-by: Michael S. Tsirkin <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>

Author: terenceli

hw/virtio/virtio-mem.c

@@ -318,6 +318,7 @@ static void virtio_mem_handle_request(VirtIODevice *vdev, VirtQueue *vq)
         if (iov_to_buf(elem->out_sg, elem->out_num, 0, &req, len) < len) {
             virtio_error(vdev, "virtio-mem protocol violation: invalid request"
                          " size: %d", len);
+            virtqueue_detach_element(vq, elem, 0);
             g_free(elem);
             return;
         }
@@ -327,6 +328,7 @@ static void virtio_mem_handle_request(VirtIODevice *vdev, VirtQueue *vq)
             virtio_error(vdev, "virtio-mem protocol violation: not enough space"
                          " for response: %zu",
                          iov_size(elem->in_sg, elem->in_num));
+            virtqueue_detach_element(vq, elem, 0);
             g_free(elem);
             return;
         }
@@ -348,6 +350,7 @@ static void virtio_mem_handle_request(VirtIODevice *vdev, VirtQueue *vq)
         default:
             virtio_error(vdev, "virtio-mem protocol violation: unknown request"
                          " type: %d", type);
+            virtqueue_detach_element(vq, elem, 0);
             g_free(elem);
             return;
         }