From 01c9c123db76357d4373b2e97b760a856d6fe822 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Tue, 25 Feb 2025 13:10:23 -0800 Subject: [PATCH] net: Use rtnl_net_dev_lock() in register_netdevice_notifier_dev_net(). Breno Leitao reported the splat below. [0] Commit 65161fb544aa ("net: Fix dev_net(dev) race in unregister_netdevice_notifier_dev_net().") added the DEBUG_NET_WARN_ON_ONCE(), assuming that the netdev is not registered before register_netdevice_notifier_dev_net(). But the assumption was simply wrong. Let's use rtnl_net_dev_lock() in register_netdevice_notifier_dev_net(). [0]: WARNING: CPU: 25 PID: 849 at net/core/dev.c:2150 register_netdevice_notifier_dev_net (net/core/dev.c:2150) ? __warn (kernel/panic.c:242 kernel/panic.c:748) ? register_netdevice_notifier_dev_net (net/core/dev.c:2150) ? register_netdevice_notifier_dev_net (net/core/dev.c:2150) ? report_bug (lib/bug.c:? lib/bug.c:219) ? handle_bug (arch/x86/kernel/traps.c:285) ? exc_invalid_op (arch/x86/kernel/traps.c:309) ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:621) ? register_netdevice_notifier_dev_net (net/core/dev.c:2150) ? register_netdevice_notifier_dev_net (./include/net/net_namespace.h:406 ./include/linux/netdevice.h:2663 net/core/dev.c:2144) mlx5e_mdev_notifier_event+0x9f/0xf0 mlx5_ib notifier_call_chain.llvm.12241336988804114627 (kernel/notifier.c:85) blocking_notifier_call_chain (kernel/notifier.c:380) mlx5_core_uplink_netdev_event_replay (drivers/net/ethernet/mellanox/mlx5/core/main.c:352) mlx5_ib_roce_init.llvm.12447516292400117075+0x1c6/0x550 mlx5_ib mlx5r_probe+0x375/0x6a0 mlx5_ib ? kernfs_put (./include/linux/instrumented.h:96 ./include/linux/atomic/atomic-arch-fallback.h:2278 ./include/linux/atomic/atomic-instrumented.h:1384 fs/kernfs/dir.c:557) ? auxiliary_match_id (drivers/base/auxiliary.c:174) ? mlx5r_mp_remove+0x160/0x160 mlx5_ib really_probe (drivers/base/dd.c:? drivers/base/dd.c:658) driver_probe_device (drivers/base/dd.c:830) __driver_attach (drivers/base/dd.c:1217) bus_for_each_dev (drivers/base/bus.c:369) ? driver_attach (drivers/base/dd.c:1157) bus_add_driver (drivers/base/bus.c:679) driver_register (drivers/base/driver.c:249) Fixes: 7fb1073300a2 ("net: Hold rtnl_net_lock() in (un)?register_netdevice_notifier_dev_net().") Reported-by: Breno Leitao Closes: https://lore.kernel.org/netdev/20250224-noisy-cordial-roadrunner-fad40c@leitao/ Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Tested-by: Breno Leitao Link: https://patch.msgid.link/20250225211023.96448-1-kuniyu@amazon.com Signed-off-by: Jakub Kicinski --- net/core/dev.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 1b252e9459fd..70c01bd1799e 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2141,21 +2141,15 @@ int register_netdevice_notifier_dev_net(struct net_device *dev, struct notifier_block *nb, struct netdev_net_notifier *nn) { - struct net *net = dev_net(dev); int err; - /* rtnl_net_lock() assumes dev is not yet published by - * register_netdevice(). - */ - DEBUG_NET_WARN_ON_ONCE(!list_empty(&dev->dev_list)); - - rtnl_net_lock(net); - err = __register_netdevice_notifier_net(net, nb, false); + rtnl_net_dev_lock(dev); + err = __register_netdevice_notifier_net(dev_net(dev), nb, false); if (!err) { nn->nb = nb; list_add(&nn->list, &dev->net_notifier_list); } - rtnl_net_unlock(net); + rtnl_net_dev_unlock(dev); return err; }