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authorIvan Vecera <ivecera@redhat.com>2021-01-25 10:44:16 +0300
committerJakub Kicinski <kuba@kernel.org>2021-01-27 04:08:59 +0300
commitf0947d0d21b219e03940b9be6628a43445c0de7a (patch)
treeb759e98feadc6d7c7c086f9bc6abe7b509a13c1f
parent5cfeb5626d4acef8df993eceec442f7b54943976 (diff)
downloadlinux-f0947d0d21b219e03940b9be6628a43445c0de7a.tar.xz
team: protect features update by RCU to avoid deadlock
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>
-rw-r--r--drivers/net/team/team.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c
index c19dac21c468..dd7917cab2b1 100644
--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -992,7 +992,8 @@ 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);
@@ -1006,6 +1007,7 @@ 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 |
@@ -1020,9 +1022,7 @@ 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);
}