From aa69918bd418e700309fdd08509dba324fb24296 Mon Sep 17 00:00:00 2001 From: Ilya Maximets Date: Fri, 1 May 2026 01:38:37 +0200 Subject: openvswitch: vport: fix self-deadlock on release of tunnel ports vports are used concurrently and protected by RCU, so netdev_put() must happen after the RCU grace period. So, either in an RCU call or after the synchronize_net(). The rtnl_delete_link() must happen under RTNL and so can't be executed in RCU context. Calling synchronize_net() while holding RTNL is not a good idea for performance and system stability under load in general, so calling netdev_put() in RCU call is the right solution here. However, when the device is deleted, rtnl_unlock() will call netdev_run_todo() and block until all the references are gone. In the current code this means that we never reach the call_rcu() and the vport is never freed and the reference is never released, causing a self-deadlock on device removal. Fix that by moving the rcu_call() before the rtnl_unlock(), so the scheduled RCU callback will be executed when synchronize_net() is called from the rtnl_unlock()->netdev_run_todo() while the RTNL itself is already released. Fixes: 6931d21f87bc ("openvswitch: defer tunnel netdev_put to RCU release") Cc: stable@vger.kernel.org Acked-by: Eelco Chaudron Signed-off-by: Ilya Maximets Acked-by: Aaron Conole Link: https://patch.msgid.link/20260430233848.440994-2-i.maximets@ovn.org Signed-off-by: Paolo Abeni --- net/openvswitch/vport-netdev.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/openvswitch/vport-netdev.c b/net/openvswitch/vport-netdev.c index a92ca8b37f96..c42642075685 100644 --- a/net/openvswitch/vport-netdev.c +++ b/net/openvswitch/vport-netdev.c @@ -208,9 +208,13 @@ void ovs_netdev_tunnel_destroy(struct vport *vport) */ if (vport->dev->reg_state == NETREG_REGISTERED) rtnl_delete_link(vport->dev, 0, NULL); - rtnl_unlock(); + /* We can't put the device reference yet, since it can still be in + * use, but rtnl_unlock()->netdev_run_todo() will block until all + * the references are released, so the RCU call must be before it. + */ call_rcu(&vport->rcu, vport_netdev_free); + rtnl_unlock(); } EXPORT_SYMBOL_GPL(ovs_netdev_tunnel_destroy); -- cgit v1.2.3