From 369f61bee0f584aee09f0736431eb9b330c98571 Mon Sep 17 00:00:00 2001 From: Taehee Yoo Date: Mon, 21 Oct 2019 18:47:54 +0000 Subject: team: fix nested locking lockdep warning team interface could be nested and it's lock variable could be nested too. But this lock uses static lockdep key and there is no nested locking handling code such as mutex_lock_nested() and so on. so the Lockdep would warn about the circular locking scenario that couldn't happen. In order to fix, this patch makes the team module to use dynamic lock key instead of static key. Test commands: ip link add team0 type team ip link add team1 type team ip link set team0 master team1 ip link set team0 nomaster ip link set team1 master team0 ip link set team1 nomaster Splat that looks like: [ 40.364352] WARNING: possible recursive locking detected [ 40.364964] 5.4.0-rc3+ #96 Not tainted [ 40.365405] -------------------------------------------- [ 40.365973] ip/750 is trying to acquire lock: [ 40.366542] ffff888060b34c40 (&team->lock){+.+.}, at: team_set_mac_address+0x151/0x290 [team] [ 40.367689] but task is already holding lock: [ 40.368729] ffff888051201c40 (&team->lock){+.+.}, at: team_del_slave+0x29/0x60 [team] [ 40.370280] other info that might help us debug this: [ 40.371159] Possible unsafe locking scenario: [ 40.371942] CPU0 [ 40.372338] ---- [ 40.372673] lock(&team->lock); [ 40.373115] lock(&team->lock); [ 40.373549] *** DEADLOCK *** [ 40.374432] May be due to missing lock nesting notation [ 40.375338] 2 locks held by ip/750: [ 40.375851] #0: ffffffffabcc42b0 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x466/0x8a0 [ 40.376927] #1: ffff888051201c40 (&team->lock){+.+.}, at: team_del_slave+0x29/0x60 [team] [ 40.377989] stack backtrace: [ 40.378650] CPU: 0 PID: 750 Comm: ip Not tainted 5.4.0-rc3+ #96 [ 40.379368] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 [ 40.380574] Call Trace: [ 40.381208] dump_stack+0x7c/0xbb [ 40.381959] __lock_acquire+0x269d/0x3de0 [ 40.382817] ? register_lock_class+0x14d0/0x14d0 [ 40.383784] ? check_chain_key+0x236/0x5d0 [ 40.384518] lock_acquire+0x164/0x3b0 [ 40.385074] ? team_set_mac_address+0x151/0x290 [team] [ 40.385805] __mutex_lock+0x14d/0x14c0 [ 40.386371] ? team_set_mac_address+0x151/0x290 [team] [ 40.387038] ? team_set_mac_address+0x151/0x290 [team] [ 40.387632] ? mutex_lock_io_nested+0x1380/0x1380 [ 40.388245] ? team_del_slave+0x60/0x60 [team] [ 40.388752] ? rcu_read_lock_sched_held+0x90/0xc0 [ 40.389304] ? rcu_read_lock_bh_held+0xa0/0xa0 [ 40.389819] ? lock_acquire+0x164/0x3b0 [ 40.390285] ? lockdep_rtnl_is_held+0x16/0x20 [ 40.390797] ? team_port_get_rtnl+0x90/0xe0 [team] [ 40.391353] ? __module_text_address+0x13/0x140 [ 40.391886] ? team_set_mac_address+0x151/0x290 [team] [ 40.392547] team_set_mac_address+0x151/0x290 [team] [ 40.393111] dev_set_mac_address+0x1f0/0x3f0 [ ... ] Fixes: 3d249d4ca7d0 ("net: introduce ethernet teaming device") Signed-off-by: Taehee Yoo Signed-off-by: David S. Miller --- drivers/net/team/team.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) (limited to 'drivers/net/team/team.c') diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c index 6cea83b48cad..8156b33ee3e7 100644 --- a/drivers/net/team/team.c +++ b/drivers/net/team/team.c @@ -1615,7 +1615,6 @@ static int team_init(struct net_device *dev) int err; team->dev = dev; - mutex_init(&team->lock); team_set_no_mode(team); team->pcpu_stats = netdev_alloc_pcpu_stats(struct team_pcpu_stats); @@ -1642,6 +1641,9 @@ static int team_init(struct net_device *dev) goto err_options_register; netif_carrier_off(dev); + lockdep_register_key(&team->team_lock_key); + __mutex_init(&team->lock, "team->team_lock_key", &team->team_lock_key); + return 0; err_options_register: @@ -1671,6 +1673,7 @@ static void team_uninit(struct net_device *dev) team_queue_override_fini(team); mutex_unlock(&team->lock); netdev_change_features(dev); + lockdep_unregister_key(&team->team_lock_key); } static void team_destructor(struct net_device *dev) @@ -1974,8 +1977,15 @@ static int team_del_slave(struct net_device *dev, struct net_device *port_dev) err = team_port_del(team, port_dev); mutex_unlock(&team->lock); - if (!err) - netdev_change_features(dev); + if (err) + return err; + + if (netif_is_team_master(port_dev)) { + lockdep_unregister_key(&team->team_lock_key); + lockdep_register_key(&team->team_lock_key); + lockdep_set_class(&team->lock, &team->team_lock_key); + } + netdev_change_features(dev); return err; } -- cgit v1.2.3