Mon, Jan 25, 2021 at 08:44:16AM CET, ivec...@redhat.com wrote:
>Function __team_compute_features() is protected by team->lock
>mutex when it is called from team_compute_features() used when
>features of an underlying device is changed. This causes
>a deadlock when NETDEV_FEAT_CHANGE notifier for underlying device
>is fired due to change propagated from team driver (e.g. MTU
>change). It's because callbacks like team_change_mtu() or
>team_vlan_rx_{add,del}_vid() protect their port list traversal
>by team->lock mutex.
>
>Example (r8169 case where this driver disables TSO for certain MTU
>values):
>...
>[ 6391.348202] __mutex_lock.isra.6+0x2d0/0x4a0
>[ 6391.358602] team_device_event+0x9d/0x160 [team]
>[ 6391.363756] notifier_call_chain+0x47/0x70
>[ 6391.368329] netdev_update_features+0x56/0x60
>[ 6391.373207] rtl8169_change_mtu+0x14/0x50 [r8169]
>[ 6391.378457] dev_set_mtu_ext+0xe1/0x1d0
>[ 6391.387022] dev_set_mtu+0x52/0x90
>[ 6391.390820] team_change_mtu+0x64/0xf0 [team]
>[ 6391.395683] dev_set_mtu_ext+0xe1/0x1d0
>[ 6391.399963] do_setlink+0x231/0xf50
>...
>
>In fact team_compute_features() called from team_device_event()
>does not need to be protected by team->lock mutex and rcu_read_lock()
>is sufficient there for port list traversal.
>
>Fixes: 3d249d4ca7d0 ("net: introduce ethernet teaming device")
>Cc: Jiri Pirko <j...@resnulli.us>
>Cc: David S. Miller <da...@davemloft.net>
>Cc: Cong Wang <xiyou.wangc...@gmail.com>
>Cc: Jakub Kicinski <k...@kernel.org>
>Cc: Saeed Mahameed <sa...@kernel.org>
>Signed-off-by: Ivan Vecera <ivec...@redhat.com>
Reviewed-by: Jiri Pirko <j...@nvidia.com>
