diff options
| author | Ivan Vecera <ivecera@redhat.com> | 2021-01-25 08:44:16 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-02-03 23:23:27 +0100 |
| commit | ed130d6329078dc0ed8f04849886535c2cd6f699 (patch) | |
| tree | b89c9031f756852a003417072d86d30b62ded51d | |
| parent | cff34a433733ea101a2c8233a18f3f2dad82d362 (diff) | |
team: protect features update by RCU to avoid deadlock
commit f0947d0d21b219e03940b9be6628a43445c0de7a upstream.
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: Saeed Mahameed <saeed@kernel.org>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20210125074416.4056484-1-ivecera@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/net/team/team.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c index 3eb034a5a659..8a1e9dba1249 100644 --- a/drivers/net/team/team.c +++ b/drivers/net/team/team.c @@ -998,7 +998,8 @@ static void __team_compute_features(struct team *team) unsigned int dst_release_flag = IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM; - list_for_each_entry(port, &team->port_list, list) { + rcu_read_lock(); + list_for_each_entry_rcu(port, &team->port_list, list) { vlan_features = netdev_increment_features(vlan_features, port->dev->vlan_features, TEAM_VLAN_FEATURES); @@ -1012,6 +1013,7 @@ static void __team_compute_features(struct team *team) if (port->dev->hard_header_len > max_hard_header_len) max_hard_header_len = port->dev->hard_header_len; } + rcu_read_unlock(); team->dev->vlan_features = vlan_features; team->dev->hw_enc_features = enc_features | NETIF_F_GSO_ENCAP_ALL | @@ -1027,9 +1029,7 @@ static void __team_compute_features(struct team *team) static void team_compute_features(struct team *team) { - mutex_lock(&team->lock); __team_compute_features(team); - mutex_unlock(&team->lock); netdev_change_features(team->dev); } |