Wed, May 25, 2016 at 09:21:52PM CEST, ivec...@redhat.com wrote: >The team_device_event() notifier calls team_compute_features() to fix >vlan_features under team->lock to protect team->port_list. The problem is >that subsequent __team_compute_features() calls netdev_change_features() >to propagate vlan_features to upper vlan devices while team->lock is still >taken. This can lead to deadlock when NETIF_F_LRO is modified on lower >devices or team device itself. > >Example: >The team0 as active backup with eth0 and eth1 NICs. Both eth0 & eth1 are >LRO capable and LRO is enabled. Thus LRO is also enabled on team0. > >The command 'ethtool -K team0 lro off' now hangs due to this deadlock: > >dev_ethtool() >-> ethtool_set_features() > -> __netdev_update_features(team) > -> netdev_sync_lower_features() > -> netdev_update_features(lower_1) > -> __netdev_update_features(lower_1) > -> netdev_features_change(lower_1) > -> call_netdevice_notifiers(...) > -> team_device_event(lower_1) > -> team_compute_features(team) [TAKES team->lock] > -> netdev_change_features(team) > -> __netdev_update_features(team) > -> netdev_sync_lower_features() > -> netdev_update_features(lower_2) > -> __netdev_update_features(lower_2) > -> netdev_features_change(lower_2) > -> call_netdevice_notifiers(...) > -> team_device_event(lower_2) > -> team_compute_features(team) [DEADLOCK] > >The bug is present in team from the beginning but it appeared after the commit >fd867d5 (net/core: generic support for disabling netdev features down stack) >that adds synchronization of features with lower devices. > >Fixes: fd867d5 (net/core: generic support for disabling netdev features down >stack) >Cc: Jiri Pirko <j...@resnulli.us> >Signed-off-by: Ivan Vecera <ivec...@redhat.com>
Signed-off-by: Jiri Pirko <j...@mellanox.com>
