From af5f54b0ef9ef72d5fc7d57f0406372e8f317958 Mon Sep 17 00:00:00 2001 From: Cosmin Ratiu Date: Fri, 9 May 2025 10:28:50 +0300 Subject: [PATCH] net: Lock lower level devices when updating features __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: 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 Fixes: 7e4d784f5810 ("net: hold netdev instance lock during rtnetlink operations") Signed-off-by: Cosmin Ratiu Acked-by: Stanislav Fomichev Link: https://patch.msgid.link/20250509072850.2002821-1-cratiu@nvidia.com Signed-off-by: Jakub Kicinski --- net/core/dev.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/core/dev.c b/net/core/dev.c index 11da1e272ec2..0d891634c692 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -10441,6 +10441,7 @@ static void netdev_sync_lower_features(struct net_device *upper, if (!(features & feature) && (lower->features & feature)) { netdev_dbg(upper, "Disabling feature %pNF on lower dev %s.\n", &feature, lower->name); + netdev_lock_ops(lower); lower->wanted_features &= ~feature; __netdev_update_features(lower); @@ -10449,6 +10450,7 @@ static void netdev_sync_lower_features(struct net_device *upper, &feature, lower->name); else netdev_features_change(lower); + netdev_unlock_ops(lower); } } }