From: Jakub Kicinski Date: Fri, 5 Jun 2026 00:29:03 +0000 (-0700) Subject: net: ethtool: make dev->hwprov ops-protected X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=97f51bf91b3afa8819fa10e9282e3f2328bb78e4;p=thirdparty%2Flinux.git net: ethtool: make dev->hwprov ops-protected dev->hwprov tracks the active hwtstamp provider for the device. Make it ops protected (instance lock if the netdev driver opts into holding instance lock around callbacks, otherwise rtnl_lock). hwprov is written and read in: - drivers/net/phy/phy_device.c phydev and ops protection don't currently mix, add a comment - net/ethtool/ as of now holds both rtnl lock and ops lock, this one will soon only hold one lock or the other read in: - net/core/dev_ioctl.c holds both rtnl lock and ops lock - net/core/timestamping.c RCU reader The new netdev_ops_lock_dereference() helper does not have "compat" in the name. The name would be quite long and I think in this case it should be obvious that we need _a_ lock. netdev_lock_dereference() already exists and means dev->lock is always expected. Reviewed-by: Eric Dumazet Acked-by: Stanislav Fomichev Reviewed-by: Jacob Keller Link: https://patch.msgid.link/20260605002912.3456868-4-kuba@kernel.org Signed-off-by: Jakub Kicinski --- diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c index 3370eb822017..ea53e477465d 100644 --- a/drivers/net/phy/phy_device.c +++ b/drivers/net/phy/phy_device.c @@ -1935,6 +1935,9 @@ void phy_detach(struct phy_device *phydev) if (dev) { struct hwtstamp_provider *hwprov; + /* hwprov may technically be protected by ops lock but + * not for devices with a phydev, see phy_link_topo_add_phy() + */ hwprov = rtnl_dereference(dev->hwprov); /* Disable timestamp if it is the one selected */ if (hwprov && hwprov->phydev == phydev) { diff --git a/drivers/net/phy/phy_link_topology.c b/drivers/net/phy/phy_link_topology.c index aed3b26c1674..4134de7ae313 100644 --- a/drivers/net/phy/phy_link_topology.c +++ b/drivers/net/phy/phy_link_topology.c @@ -38,7 +38,9 @@ int phy_link_topo_add_phy(struct net_device *dev, /* ethtool ops may run without rtnl_lock, and rtnl_lock is what * currently protects the PHY topology. No driver currently mixes - * the two, flag if someone tries. See also ethnl_req_get_phydev(). + * the two, flag if someone tries. See also: + * - ethnl_req_get_phydev() + * - phy_detach() */ if (WARN_ON_ONCE(netdev_need_ops_lock(dev))) return -EOPNOTSUPP; diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 74507c006490..a8709d0cc8d4 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2583,6 +2583,9 @@ struct net_device { * Double protects: * @up, @moving_ns, @nd_net, @xdp_features * + * Ops protects: + * @hwprov + * * Double ops protects: * @real_num_rx_queues, @real_num_tx_queues * diff --git a/include/net/netdev_lock.h b/include/net/netdev_lock.h index d3daec4e93f3..9fb3e93857c3 100644 --- a/include/net/netdev_lock.h +++ b/include/net/netdev_lock.h @@ -102,6 +102,14 @@ static inline void netdev_unlock_ops_compat(struct net_device *dev) rtnl_unlock(); } +/* Matching "ops protected" category from netdevice.h */ +static inline int netdev_is_locked_ops_compat(const struct net_device *dev) +{ + if (netdev_need_ops_lock(dev)) + return lockdep_is_held(&dev->lock); + return lockdep_rtnl_is_held(); +} + static inline int netdev_lock_cmp_fn(const struct lockdep_map *a, const struct lockdep_map *b) { @@ -138,6 +146,9 @@ static inline int netdev_lock_cmp_fn(const struct lockdep_map *a, #define netdev_lock_dereference(p, dev) \ rcu_dereference_protected(p, lockdep_is_held(&(dev)->lock)) +#define netdev_ops_lock_dereference(p, dev) \ + rcu_dereference_protected(p, netdev_is_locked_ops_compat(dev)) + int netdev_debug_event(struct notifier_block *nb, unsigned long event, void *ptr); diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c index f3979b276090..a320e264eaaf 100644 --- a/net/core/dev_ioctl.c +++ b/net/core/dev_ioctl.c @@ -260,7 +260,7 @@ int dev_get_hwtstamp_phylib(struct net_device *dev, { struct hwtstamp_provider *hwprov; - hwprov = rtnl_dereference(dev->hwprov); + hwprov = netdev_ops_lock_dereference(dev->hwprov, dev); if (hwprov) { cfg->qualifier = hwprov->desc.qualifier; if (hwprov->source == HWTSTAMP_SOURCE_PHYLIB && @@ -337,7 +337,7 @@ int dev_set_hwtstamp_phylib(struct net_device *dev, bool phy_ts; int err; - hwprov = rtnl_dereference(dev->hwprov); + hwprov = netdev_ops_lock_dereference(dev->hwprov, dev); if (hwprov) { if (hwprov->source == HWTSTAMP_SOURCE_PHYLIB && hwprov->phydev) { diff --git a/net/ethtool/tsconfig.c b/net/ethtool/tsconfig.c index 664c3fe49b5b..24b64862011f 100644 --- a/net/ethtool/tsconfig.c +++ b/net/ethtool/tsconfig.c @@ -2,6 +2,7 @@ #include #include +#include #include "bitset.h" #include "common.h" @@ -57,7 +58,7 @@ static int tsconfig_prepare_data(const struct ethnl_req_info *req_base, data->hwtst_config.flags = cfg.flags; data->hwprov_desc.index = -1; - hwprov = rtnl_dereference(dev->hwprov); + hwprov = netdev_ops_lock_dereference(dev->hwprov, dev); if (hwprov) { data->hwprov_desc.index = hwprov->desc.index; data->hwprov_desc.qualifier = hwprov->desc.qualifier; @@ -213,7 +214,7 @@ static int tsconfig_send_reply(struct net_device *dev, struct genl_info *info) return -ENOMEM; } - ASSERT_RTNL(); + netdev_assert_locked_ops_compat(dev); reply_data->base.dev = dev; ret = tsconfig_prepare_data(&req_info->base, &reply_data->base, info); if (ret < 0) @@ -316,7 +317,7 @@ static int ethnl_set_tsconfig(struct ethnl_req_info *req_base, struct hwtstamp_provider_desc __hwprov_desc = {.index = -1}; struct hwtstamp_provider *__hwprov; - __hwprov = rtnl_dereference(dev->hwprov); + __hwprov = netdev_ops_lock_dereference(dev->hwprov, dev); if (__hwprov) { __hwprov_desc.index = __hwprov->desc.index; __hwprov_desc.qualifier = __hwprov->desc.qualifier; @@ -414,7 +415,8 @@ static int ethnl_set_tsconfig(struct ethnl_req_info *req_base, goto err_free_hwprov; /* Change the selected hwtstamp source */ - __hwprov = rcu_replace_pointer_rtnl(dev->hwprov, hwprov); + __hwprov = rcu_replace_pointer(dev->hwprov, hwprov, + netdev_is_locked_ops_compat(dev)); if (__hwprov) kfree_rcu(__hwprov, rcu_head); }