__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: 7e4d784f58 ("net: hold netdev instance lock during rtnetlink operations")
Signed-off-by: Cosmin Ratiu <cratiu@nvidia.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250509072850.2002821-1-cratiu@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
af5f54b0ef