The openvswitch teardown code will immediately call ovs_netdev_detach_dev() in response to a NETDEV_UNREGISTER notification. It will then start the dp_notify_work workqueue, which will later end up calling the vport destroy() callback. This callback takes the RTNL to do another ovs_netdev_detach_port(), which in this case is unnecessary. This causes extra pressure on the RTNL, in some cases leading to "unregister_netdevice: waiting for XX to become free" warnings on teardown. We can straight-forwardly avoid the extra RTNL lock acquisition by checking the device flags before taking the lock, and skip the locking altogether if the IFF_OVS_DATAPATH flag has already been unset. Fixes: b07c26511e94 ("openvswitch: fix vport-netdev unregister") Tested-by: Adrian Moreno Signed-off-by: Toke Høiland-Jørgensen --- net/openvswitch/vport-netdev.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/net/openvswitch/vport-netdev.c b/net/openvswitch/vport-netdev.c index 91a11067e458..519f038526f9 100644 --- a/net/openvswitch/vport-netdev.c +++ b/net/openvswitch/vport-netdev.c @@ -160,10 +160,13 @@ void ovs_netdev_detach_dev(struct vport *vport) static void netdev_destroy(struct vport *vport) { - rtnl_lock(); - if (netif_is_ovs_port(vport->dev)) - ovs_netdev_detach_dev(vport); - rtnl_unlock(); + if (netif_is_ovs_port(vport->dev)) { + rtnl_lock(); + /* check again while holding the lock */ + if (netif_is_ovs_port(vport->dev)) + ovs_netdev_detach_dev(vport); + rtnl_unlock(); + } call_rcu(&vport->rcu, vport_netdev_free); } -- 2.52.0