| Message ID | 1464204112-4044-1-git-send-email-ivecera@redhat.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
Wed, May 25, 2016 at 09:21:52PM CEST, ivecera@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 <jiri@resnulli.us> >Signed-off-by: Ivan Vecera <ivecera@redhat.com> Signed-off-by: Jiri Pirko <jiri@mellanox.com>
From: Ivan Vecera <ivecera@redhat.com> Date: Wed, 25 May 2016 21:21:52 +0200 > 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: ... > 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 <jiri@resnulli.us> > Signed-off-by: Ivan Vecera <ivecera@redhat.com> Applied and queued up for -stable, thanks.
diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c index 718ceea..800a449 100644 --- a/drivers/net/team/team.c +++ b/drivers/net/team/team.c @@ -988,7 +988,7 @@ static void team_port_disable(struct team *team, #define TEAM_ENC_FEATURES (NETIF_F_HW_CSUM | NETIF_F_SG | \ NETIF_F_RXCSUM | NETIF_F_ALL_TSO) -static void __team_compute_features(struct team *team) +static void ___team_compute_features(struct team *team) { struct team_port *port; u32 vlan_features = TEAM_VLAN_FEATURES & NETIF_F_ALL_FOR_ALL; @@ -1019,15 +1019,20 @@ static void __team_compute_features(struct team *team) team->dev->priv_flags &= ~IFF_XMIT_DST_RELEASE; if (dst_release_flag == (IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM)) team->dev->priv_flags |= IFF_XMIT_DST_RELEASE; +} +static void __team_compute_features(struct team *team) +{ + ___team_compute_features(team); netdev_change_features(team->dev); } static void team_compute_features(struct team *team) { mutex_lock(&team->lock); - __team_compute_features(team); + ___team_compute_features(team); mutex_unlock(&team->lock); + netdev_change_features(team->dev); } static int team_port_enter(struct team *team, struct team_port *port)
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 <jiri@resnulli.us> Signed-off-by: Ivan Vecera <ivecera@redhat.com> --- drivers/net/team/team.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)