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When enable debug config, it print below warning while shut down wlan interface shuh as run "ifconfig wlan0 down". The reason is because ar->regd_update_work is ran once, and it is will call wiphy_lock(ar->hw->wiphy) in function ath11k_regd_update() which is running in workqueue of ieee80211_local queued by ieee80211_queue_work(). Another thread from "ifconfig wlan0 down" will also accuqire the lock by wiphy_lock(sdata->local->hw.wiphy) in function ieee80211_stop(), and then it call ieee80211_stop_device() to flush_workqueue(local->workqueue), this will wait the workqueue of ieee80211_local finished. Then deadlock will happen easily if the two thread run meanwhile. Below warning disappeared after this change. [ 914.088798] ath11k_pci 0000:05:00.0: mac remove interface (vdev 0) [ 914.088806] ath11k_pci 0000:05:00.0: mac stop 11d scan [ 914.088810] ath11k_pci 0000:05:00.0: mac stop 11d vdev id 0 [ 914.088827] ath11k_pci 0000:05:00.0: htc ep 2 consumed 1 credits (total 0) [ 914.088841] ath11k_pci 0000:05:00.0: send 11d scan stop vdev id 0 [ 914.088849] ath11k_pci 0000:05:00.0: htc insufficient credits ep 2 required 1 available 0 [ 914.088856] ath11k_pci 0000:05:00.0: htc insufficient credits ep 2 required 1 available 0 [ 914.096434] ath11k_pci 0000:05:00.0: rx ce pipe 2 len 16 [ 914.096442] ath11k_pci 0000:05:00.0: htc ep 2 got 1 credits (total 1) [ 914.096481] ath11k_pci 0000:05:00.0: htc ep 2 consumed 1 credits (total 0) [ 914.096491] ath11k_pci 0000:05:00.0: WMI vdev delete id 0 [ 914.111598] ath11k_pci 0000:05:00.0: rx ce pipe 2 len 16 [ 914.111628] ath11k_pci 0000:05:00.0: htc ep 2 got 1 credits (total 1) [ 914.114659] ath11k_pci 0000:05:00.0: rx ce pipe 2 len 20 [ 914.114742] ath11k_pci 0000:05:00.0: htc rx completion ep 2 skb pK-error [ 914.115977] ath11k_pci 0000:05:00.0: vdev delete resp for vdev id 0 [ 914.116685] ath11k_pci 0000:05:00.0: vdev 00:03:7f:29:61:11 deleted, vdev_id 0 [ 914.117583] ====================================================== [ 914.117592] WARNING: possible circular locking dependency detected [ 914.117600] 5.16.0-rc1-wt-ath+ #1 Tainted: G OE [ 914.117611] ------------------------------------------------------ [ 914.117618] ifconfig/2805 is trying to acquire lock: [ 914.117628] ffff9c00a62bb548 ((wq_completion)phy0){+.+.}-{0:0}, at: flush_workqueue+0x87/0x470 [ 914.117674] but task is already holding lock: [ 914.117682] ffff9c00baea07d0 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: ieee80211_stop+0x38/0x180 [mac80211] [ 914.117872] which lock already depends on the new lock. [ 914.117880] the existing dependency chain (in reverse order) is: [ 914.117888] -> #3 (&rdev->wiphy.mtx){+.+.}-{4:4}: [ 914.117910] __mutex_lock+0xa0/0x9c0 [ 914.117930] mutex_lock_nested+0x1b/0x20 [ 914.117944] reg_process_self_managed_hints+0x3a/0xb0 [cfg80211] [ 914.118093] wiphy_regulatory_register+0x47/0x80 [cfg80211] [ 914.118229] wiphy_register+0x84f/0x9c0 [cfg80211] [ 914.118353] ieee80211_register_hw+0x6b1/0xd90 [mac80211] [ 914.118486] ath11k_mac_register+0x6af/0xb60 [ath11k] [ 914.118550] ath11k_core_qmi_firmware_ready+0x383/0x4a0 [ath11k] [ 914.118598] ath11k_qmi_driver_event_work+0x347/0x4a0 [ath11k] [ 914.118656] process_one_work+0x228/0x670 [ 914.118669] worker_thread+0x4d/0x440 [ 914.118680] kthread+0x16d/0x1b0 [ 914.118697] ret_from_fork+0x22/0x30 [ 914.118714] -> #2 (rtnl_mutex){+.+.}-{4:4}: [ 914.118736] __mutex_lock+0xa0/0x9c0 [ 914.118751] mutex_lock_nested+0x1b/0x20 [ 914.118767] rtnl_lock+0x17/0x20 [ 914.118783] ath11k_regd_update+0x15a/0x260 [ath11k] [ 914.118841] ath11k_regd_update_work+0x15/0x20 [ath11k] [ 914.118897] process_one_work+0x228/0x670 [ 914.118909] worker_thread+0x4d/0x440 [ 914.118920] kthread+0x16d/0x1b0 [ 914.118934] ret_from_fork+0x22/0x30 [ 914.118948] -> #1 ((work_completion)(&ar->regd_update_work)){+.+.}-{0:0}: [ 914.118972] process_one_work+0x1fa/0x670 [ 914.118984] worker_thread+0x4d/0x440 [ 914.118996] kthread+0x16d/0x1b0 [ 914.119010] ret_from_fork+0x22/0x30 [ 914.119023] -> #0 ((wq_completion)phy0){+.+.}-{0:0}: [ 914.119045] __lock_acquire+0x146d/0x1cf0 [ 914.119057] lock_acquire+0x19b/0x360 [ 914.119067] flush_workqueue+0xae/0x470 [ 914.119084] ieee80211_stop_device+0x3b/0x50 [mac80211] [ 914.119260] ieee80211_do_stop+0x5d7/0x830 [mac80211] [ 914.119409] ieee80211_stop+0x45/0x180 [mac80211] [ 914.119557] __dev_close_many+0xb3/0x120 [ 914.119573] __dev_change_flags+0xc3/0x1d0 [ 914.119590] dev_change_flags+0x29/0x70 [ 914.119605] devinet_ioctl+0x653/0x810 [ 914.119620] inet_ioctl+0x193/0x1e0 [ 914.119631] sock_do_ioctl+0x4d/0xf0 [ 914.119649] sock_ioctl+0x262/0x340 [ 914.119665] __x64_sys_ioctl+0x96/0xd0 [ 914.119678] do_syscall_64+0x3d/0xd0 [ 914.119694] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 914.119709] other info that might help us debug this: [ 914.119717] Chain exists of: (wq_completion)phy0 --> rtnl_mutex --> &rdev->wiphy.mtx [ 914.119745] Possible unsafe locking scenario: [ 914.119752] CPU0 CPU1 [ 914.119758] ---- ---- [ 914.119765] lock(&rdev->wiphy.mtx); [ 914.119778] lock(rtnl_mutex); [ 914.119792] lock(&rdev->wiphy.mtx); [ 914.119807] lock((wq_completion)phy0); [ 914.119819] *** DEADLOCK *** [ 914.119827] 2 locks held by ifconfig/2805: [ 914.119837] #0: ffffffffba3dc010 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock+0x17/0x20 [ 914.119872] #1: ffff9c00baea07d0 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: ieee80211_stop+0x38/0x180 [mac80211] [ 914.120039] stack backtrace: [ 914.120048] CPU: 0 PID: 2805 Comm: ifconfig Tainted: G OE 5.16.0-rc1-wt-ath+ #1 [ 914.120064] Hardware name: LENOVO 418065C/418065C, BIOS 83ET63WW (1.33 ) 07/29/2011 [ 914.120074] Call Trace: [ 914.120084] <TASK> [ 914.120094] dump_stack_lvl+0x73/0xa4 [ 914.120119] dump_stack+0x10/0x12 [ 914.120135] print_circular_bug.isra.44+0x221/0x2e0 [ 914.120165] check_noncircular+0x106/0x150 [ 914.120203] __lock_acquire+0x146d/0x1cf0 [ 914.120215] ? __lock_acquire+0x146d/0x1cf0 [ 914.120245] lock_acquire+0x19b/0x360 [ 914.120259] ? flush_workqueue+0x87/0x470 [ 914.120286] ? lockdep_init_map_type+0x6b/0x250 [ 914.120310] flush_workqueue+0xae/0x470 [ 914.120327] ? flush_workqueue+0x87/0x470 [ 914.120344] ? lockdep_hardirqs_on+0xd7/0x150 [ 914.120391] ieee80211_stop_device+0x3b/0x50 [mac80211] [ 914.120565] ? ieee80211_stop_device+0x3b/0x50 [mac80211] [ 914.120736] ieee80211_do_stop+0x5d7/0x830 [mac80211] [ 914.120906] ieee80211_stop+0x45/0x180 [mac80211] [ 914.121060] __dev_close_many+0xb3/0x120 [ 914.121081] __dev_change_flags+0xc3/0x1d0 [ 914.121109] dev_change_flags+0x29/0x70 [ 914.121131] devinet_ioctl+0x653/0x810 [ 914.121149] ? __might_fault+0x77/0x80 [ 914.121179] inet_ioctl+0x193/0x1e0 [ 914.121194] ? inet_ioctl+0x193/0x1e0 [ 914.121218] ? __might_fault+0x77/0x80 [ 914.121238] ? _copy_to_user+0x68/0x80 [ 914.121266] sock_do_ioctl+0x4d/0xf0 [ 914.121283] ? inet_stream_connect+0x60/0x60 [ 914.121297] ? sock_do_ioctl+0x4d/0xf0 [ 914.121329] sock_ioctl+0x262/0x340 [ 914.121347] ? sock_ioctl+0x262/0x340 [ 914.121362] ? exit_to_user_mode_prepare+0x13b/0x280 [ 914.121388] ? syscall_enter_from_user_mode+0x20/0x50 [ 914.121416] __x64_sys_ioctl+0x96/0xd0 [ 914.121430] ? br_ioctl_call+0x90/0x90 [ 914.121445] ? __x64_sys_ioctl+0x96/0xd0 [ 914.121465] do_syscall_64+0x3d/0xd0 [ 914.121482] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 914.121497] RIP: 0033:0x7f0ed051737b [ 914.121513] Code: 0f 1e fa 48 8b 05 15 3b 0d 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e5 3a 0d 00 f7 d8 64 89 01 48 [ 914.121527] RSP: 002b:00007fff7be38b98 EFLAGS: 00000202 ORIG_RAX: 0000000000000010 [ 914.121544] RAX: ffffffffffffffda RBX: 00007fff7be38ba0 RCX: 00007f0ed051737b [ 914.121555] RDX: 00007fff7be38ba0 RSI: 0000000000008914 RDI: 0000000000000004 [ 914.121566] RBP: 00007fff7be38c60 R08: 000000000000000a R09: 0000000000000001 [ 914.121576] R10: 0000000000000000 R11: 0000000000000202 R12: 00000000fffffffe [ 914.121586] R13: 0000000000000004 R14: 0000000000000000 R15: 0000000000000000 [ 914.121620] </TASK> Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-01720.1-QCAHSPSWPL_V1_V2_SILICONZ_LITE-1 Signed-off-by: Wen Gong <quic_wgong@quicinc.com> Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com> Link: https://lore.kernel.org/r/20211201071745.17746-2-quic_wgong@quicinc.com
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