Somehow two copies of the line 'up_write(&vf->efx->filter_sem);' got into
 efx_ef10_sriov_set_vf_vlan().  This would put the mutex in a bad state and
 cause all subsequent down attempts to hang.
Fixes: 671b53eec2ed ("sfc: Ensure down_write(&filter_sem) and up_write() are matched before calling efx_net_open()")
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
                up_write(&vf->efx->filter_sem);
                mutex_unlock(&vf->efx->mac_lock);
 
-               up_write(&vf->efx->filter_sem);
-
                rc2 = efx_net_open(vf->efx->net_dev);
                if (rc2)
                        goto reset_nic;