__netdev_update_features() expects the netdevice to be ops-locked, but it gets called recursively on the lower level netdevices to sync their features, and nothing locks those.
This commit fixes that, with the assumption that it shouldn't be possible for both higher-level and lover-level netdevices to require the instance lock, because that would lead to lock dependency warnings.
Without this, playing with higher level (e.g. vxlan) netdevices on top of netdevices with instance locking enabled can run into issues:
WARNING: CPU: 59 PID: 206496 at ./include/net/netdev_lock.h:17 netif_napi_add_weight_locked+0x753/0xa60 [...] Call Trace: <TASK> mlx5e_open_channel+0xc09/0x3740 [mlx5_core] mlx5e_open_channels+0x1f0/0x770 [mlx5_core] mlx5e_safe_switch_params+0x1b5/0x2e0 [mlx5_core] set_feature_lro+0x1c2/0x330 [mlx5_core] mlx5e_handle_feature+0xc8/0x140 [mlx5_core] mlx5e_set_features+0x233/0x2e0 [mlx5_core] __netdev_update_features+0x5be/0x1670 __netdev_update_features+0x71f/0x1670 dev_ethtool+0x21c5/0x4aa0 dev_ioctl+0x438/0xae0 sock_ioctl+0x2ba/0x690 __x64_sys_ioctl+0xa78/0x1700 do_syscall_64+0x6d/0x140 entry_SYSCALL_64_after_hwframe+0x4b/0x53 </TASK>
Fixes: 7e4d784f5810 ("net: hold netdev instance lock during rtnetlink operations") Signed-off-by: Cosmin Ratiu cratiu@nvidia.com --- net/core/dev.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/net/core/dev.c b/net/core/dev.c index 1be7cb73a602..77472364225c 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -10620,8 +10620,11 @@ int __netdev_update_features(struct net_device *dev) /* some features must be disabled on lower devices when disabled * on an upper device (think: bonding master or bridge) */ - netdev_for_each_lower_dev(dev, lower, iter) + netdev_for_each_lower_dev(dev, lower, iter) { + netdev_lock_ops(lower); netdev_sync_lower_features(dev, lower, features); + netdev_unlock_ops(lower); + }
if (!err) { netdev_features_t diff = features ^ dev->features;