From: Jakub Kicinski Date: Tue, 8 Apr 2025 19:59:52 +0000 (-0700) Subject: xdp: double protect netdev->xdp_flags with netdev->lock X-Git-Tag: v6.16-rc1~132^2~353^2~3 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=03df156dd3a6;p=thirdparty%2Flinux.git xdp: double protect netdev->xdp_flags with netdev->lock Protect xdp_features with netdev->lock. This way pure readers no longer have to take rtnl_lock to access the field. This includes calling NETDEV_XDP_FEAT_CHANGE under the lock. Looks like that's fine for bonding, the only "real" listener, it's the same as ethtool feature change. In terms of normal drivers - only GVE need special consideration (other drivers don't use instance lock or don't support XDP). It calls xdp_set_features_flag() helper from gve_init_priv() which in turn is called from gve_reset_recovery() (locked), or prior to netdev registration. So switch to _locked. Reviewed-by: Joe Damato Acked-by: Stanislav Fomichev Acked-by: Harshitha Ramamurthy Acked-by: Martin KaFai Lau Link: https://patch.msgid.link/20250408195956.412733-6-kuba@kernel.org Signed-off-by: Jakub Kicinski --- diff --git a/Documentation/networking/netdevices.rst b/Documentation/networking/netdevices.rst index 6c2d8945f5979..d6357472d3f19 100644 --- a/Documentation/networking/netdevices.rst +++ b/Documentation/networking/netdevices.rst @@ -354,6 +354,7 @@ For devices with locked ops, currently only the following notifiers are running under the lock: * ``NETDEV_REGISTER`` * ``NETDEV_UP`` +* ``NETDEV_XDP_FEAT_CHANGE`` The following notifiers are running without the lock: * ``NETDEV_UNREGISTER`` diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c index f9a73c9568614..7a249baee316a 100644 --- a/drivers/net/ethernet/google/gve/gve_main.c +++ b/drivers/net/ethernet/google/gve/gve_main.c @@ -2185,7 +2185,7 @@ static void gve_set_netdev_xdp_features(struct gve_priv *priv) xdp_features = 0; } - xdp_set_features_flag(priv->dev, xdp_features); + xdp_set_features_flag_locked(priv->dev, xdp_features); } static int gve_init_priv(struct gve_priv *priv, bool skip_describe_device) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 7242fb8a22fc5..dece2ae396a1e 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2526,7 +2526,7 @@ struct net_device { * @net_shaper_hierarchy, @reg_state, @threaded * * Double protects: - * @up, @moving_ns, @nd_net + * @up, @moving_ns, @nd_net, @xdp_flags * * Double ops protects: * @real_num_rx_queues, @real_num_tx_queues diff --git a/include/net/xdp.h b/include/net/xdp.h index 48efacbaa35da..20e41b5ff319a 100644 --- a/include/net/xdp.h +++ b/include/net/xdp.h @@ -616,6 +616,7 @@ struct xdp_metadata_ops { u32 bpf_xdp_metadata_kfunc_id(int id); bool bpf_dev_bound_kfunc_id(u32 btf_id); void xdp_set_features_flag(struct net_device *dev, xdp_features_t val); +void xdp_set_features_flag_locked(struct net_device *dev, xdp_features_t val); void xdp_features_set_redirect_target(struct net_device *dev, bool support_sg); void xdp_features_clear_redirect_target(struct net_device *dev); #else diff --git a/net/core/lock_debug.c b/net/core/lock_debug.c index b7f22dc92a6f3..598c443ef2f39 100644 --- a/net/core/lock_debug.c +++ b/net/core/lock_debug.c @@ -20,6 +20,7 @@ int netdev_debug_event(struct notifier_block *nb, unsigned long event, switch (cmd) { case NETDEV_REGISTER: case NETDEV_UP: + case NETDEV_XDP_FEAT_CHANGE: netdev_ops_assert_locked(dev); fallthrough; case NETDEV_DOWN: @@ -58,7 +59,6 @@ int netdev_debug_event(struct notifier_block *nb, unsigned long event, case NETDEV_OFFLOAD_XSTATS_DISABLE: case NETDEV_OFFLOAD_XSTATS_REPORT_USED: case NETDEV_OFFLOAD_XSTATS_REPORT_DELTA: - case NETDEV_XDP_FEAT_CHANGE: ASSERT_RTNL(); break; diff --git a/net/core/xdp.c b/net/core/xdp.c index f86eedad586a7..3cd0db9c9d2d3 100644 --- a/net/core/xdp.c +++ b/net/core/xdp.c @@ -17,6 +17,7 @@ #include #include +#include #include #include /* struct xdp_mem_allocator */ #include @@ -991,17 +992,26 @@ static int __init xdp_metadata_init(void) } late_initcall(xdp_metadata_init); -void xdp_set_features_flag(struct net_device *dev, xdp_features_t val) +void xdp_set_features_flag_locked(struct net_device *dev, xdp_features_t val) { val &= NETDEV_XDP_ACT_MASK; if (dev->xdp_features == val) return; + netdev_assert_locked_or_invisible(dev); dev->xdp_features = val; if (dev->reg_state == NETREG_REGISTERED) call_netdevice_notifiers(NETDEV_XDP_FEAT_CHANGE, dev); } +EXPORT_SYMBOL_GPL(xdp_set_features_flag_locked); + +void xdp_set_features_flag(struct net_device *dev, xdp_features_t val) +{ + netdev_lock(dev); + xdp_set_features_flag_locked(dev, val); + netdev_unlock(dev); +} EXPORT_SYMBOL_GPL(xdp_set_features_flag); void xdp_features_set_redirect_target(struct net_device *dev, bool support_sg)