From 5b0efb4d670c8b53b25c166967efd2a02b309e05 Mon Sep 17 00:00:00 2001 From: Stanislaw Gruszka Date: Fri, 3 May 2019 14:29:07 +0200 Subject: [PATCH] rtw88: avoid circular locking between local->iflist_mtx and rtwdev->mutex Remove circular lock dependency by using atomic version of interfaces iterate in watch_dog_work(), hence avoid taking local->iflist_mtx (rtw_vif_watch_dog_iter() only update some data, it can be called from atomic context). Fixes below LOCKDEP warning: [ 1157.219415] ====================================================== [ 1157.225772] [ INFO: possible circular locking dependency detected ] [ 1157.232150] 3.10.0-1043.el7.sgruszka1.x86_64.debug #1 Not tainted [ 1157.238346] ------------------------------------------------------- [ 1157.244635] kworker/u4:2/14490 is trying to acquire lock: [ 1157.250194] (&rtwdev->mutex){+.+.+.}, at: [] rtw_ops_config+0x2b/0x90 [rtw88] [ 1157.259151] but task is already holding lock: [ 1157.265085] (&local->iflist_mtx){+.+...}, at: [] ieee80211_mgd_probe_ap.part.28+0xca/0x160 [mac80211] [ 1157.276169] which lock already depends on the new lock. [ 1157.284488] the existing dependency chain (in reverse order) is: [ 1157.292101] -> #2 (&local->iflist_mtx){+.+...}: [ 1157.296919] [] lock_acquire+0x99/0x1e0 [ 1157.302955] [] mutex_lock_nested+0x93/0x410 [ 1157.309416] [] ieee80211_iterate_interfaces+0x2f/0x60 [mac80211] [ 1157.317730] [] rtw_watch_dog_work+0xcb/0x130 [rtw88] [ 1157.325003] [] process_one_work+0x22c/0x720 [ 1157.331481] [] worker_thread+0x126/0x3b0 [ 1157.337589] [] kthread+0xef/0x100 [ 1157.343260] [] ret_from_fork_nospec_end+0x0/0x39 [ 1157.350091] -> #1 ((&(&rtwdev->watch_dog_work)->work)){+.+...}: [ 1157.356314] [] lock_acquire+0x99/0x1e0 [ 1157.362427] [] flush_work+0x5b/0x310 [ 1157.368287] [] __cancel_work_timer+0xae/0x170 [ 1157.374940] [] cancel_delayed_work_sync+0x13/0x20 [ 1157.381930] [] rtw_core_stop+0x29/0x50 [rtw88] [ 1157.388679] [] rtw_enter_ips+0x16/0x20 [rtw88] [ 1157.395428] [] rtw_ops_config+0x42/0x90 [rtw88] [ 1157.402173] [] ieee80211_hw_config+0xc3/0x680 [mac80211] [ 1157.409854] [] ieee80211_do_open+0x69b/0x9c0 [mac80211] [ 1157.417418] [] ieee80211_open+0x69/0x70 [mac80211] [ 1157.424496] [] __dev_open+0xe2/0x160 [ 1157.430356] [] __dev_change_flags+0xa3/0x180 [ 1157.436922] [] dev_change_flags+0x29/0x60 [ 1157.443224] [] devinet_ioctl+0x794/0x890 [ 1157.449331] [] inet_ioctl+0x75/0xa0 [ 1157.455087] [] sock_do_ioctl+0x2b/0x60 [ 1157.461178] [] sock_ioctl+0x233/0x310 [ 1157.467109] [] do_vfs_ioctl+0x410/0x6c0 [ 1157.473233] [] SyS_ioctl+0xa1/0xc0 [ 1157.478914] [] system_call_fastpath+0x25/0x2a [ 1157.485569] -> #0 (&rtwdev->mutex){+.+.+.}: [ 1157.490022] [] __lock_acquire+0xec1/0x1630 [ 1157.496305] [] lock_acquire+0x99/0x1e0 [ 1157.502413] [] mutex_lock_nested+0x93/0x410 [ 1157.508890] [] rtw_ops_config+0x2b/0x90 [rtw88] [ 1157.515724] [] ieee80211_hw_config+0xc3/0x680 [mac80211] [ 1157.523370] [] ieee80211_recalc_ps.part.27+0x9a/0x180 [mac80211] [ 1157.531685] [] ieee80211_mgd_probe_ap.part.28+0x115/0x160 [mac80211] [ 1157.540353] [] ieee80211_beacon_connection_loss_work+0x4d/0x80 [mac80211] [ 1157.549513] [] process_one_work+0x22c/0x720 [ 1157.555886] [] worker_thread+0x126/0x3b0 [ 1157.562170] [] kthread+0xef/0x100 [ 1157.567765] [] ret_from_fork_nospec_end+0x0/0x39 [ 1157.574579] other info that might help us debug this: [ 1157.582788] Chain exists of: &rtwdev->mutex --> (&(&rtwdev->watch_dog_work)->work) --> &local->iflist_mtx [ 1157.593024] Possible unsafe locking scenario: [ 1157.599046] CPU0 CPU1 [ 1157.603653] ---- ---- [ 1157.608258] lock(&local->iflist_mtx); [ 1157.612180] lock((&(&rtwdev->watch_dog_work)->work)); [ 1157.620074] lock(&local->iflist_mtx); [ 1157.626555] lock(&rtwdev->mutex); [ 1157.630124] *** DEADLOCK *** [ 1157.636148] 4 locks held by kworker/u4:2/14490: [ 1157.640755] #0: (%s#6){.+.+.+}, at: [] process_one_work+0x1ba/0x720 [ 1157.648965] #1: ((&ifmgd->beacon_connection_loss_work)){+.+.+.}, at: [] process_one_work+0x1ba/0x720 [ 1157.659950] #2: (&wdev->mtx){+.+.+.}, at: [] ieee80211_mgd_probe_ap.part.28+0x25/0x160 [mac80211] [ 1157.670901] #3: (&local->iflist_mtx){+.+...}, at: [] ieee80211_mgd_probe_ap.part.28+0xca/0x160 [mac80211] [ 1157.682466] Fixes: e3037485c68e ("rtw88: new Realtek 802.11ac driver") Signed-off-by: Stanislaw Gruszka Acked-by: Yan-Hsuan Chuang Signed-off-by: Kalle Valo --- drivers/net/wireless/realtek/rtw88/main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireless/realtek/rtw88/main.c b/drivers/net/wireless/realtek/rtw88/main.c index f447361..b2dac460 100644 --- a/drivers/net/wireless/realtek/rtw88/main.c +++ b/drivers/net/wireless/realtek/rtw88/main.c @@ -162,7 +162,8 @@ static void rtw_watch_dog_work(struct work_struct *work) rtwdev->stats.tx_cnt = 0; rtwdev->stats.rx_cnt = 0; - rtw_iterate_vifs(rtwdev, rtw_vif_watch_dog_iter, &data); + /* use atomic version to avoid taking local->iflist_mtx mutex */ + rtw_iterate_vifs_atomic(rtwdev, rtw_vif_watch_dog_iter, &data); /* fw supports only one station associated to enter lps, if there are * more than two stations associated to the AP, then we can not enter -- 2.7.4