From: Wen Gong quic_wgong@quicinc.com
commit f45cb6b29cd36514e13f7519770873d8c0457008 upstream.
(cherry picked from commit d99884ad9e3673a12879bc2830f6e5a66cccbd78 in ath-next as users are seeing this bug more now, also cc stable)
Running this test in a loop it is easy to reproduce an rtnl deadlock:
iw reg set FI ifconfig wlan0 down
What happens is that thread A (workqueue) tries to update the regulatory:
try to acquire the rtnl_lock of ar->regd_update_work
rtnl_lock+0x17/0x20 ath11k_regd_update+0x15a/0x260 [ath11k] ath11k_regd_update_work+0x15/0x20 [ath11k] process_one_work+0x228/0x670 worker_thread+0x4d/0x440 kthread+0x16d/0x1b0 ret_from_fork+0x22/0x30
And thread B (ifconfig) tries to stop the interface:
try to cancel_work_sync(&ar->regd_update_work) in ath11k_mac_op_stop(). ifconfig 3109 [003] 2414.232506: probe:
ath11k_mac_op_stop: (ffffffffc14187a0) drv_stop+0x30 ([mac80211]) ieee80211_do_stop+0x5d2 ([mac80211]) ieee80211_stop+0x3e ([mac80211]) __dev_close_many+0x9e ([kernel.kallsyms]) __dev_change_flags+0xbe ([kernel.kallsyms]) dev_change_flags+0x23 ([kernel.kallsyms]) devinet_ioctl+0x5e3 ([kernel.kallsyms]) inet_ioctl+0x197 ([kernel.kallsyms]) sock_do_ioctl+0x4d ([kernel.kallsyms]) sock_ioctl+0x264 ([kernel.kallsyms]) __x64_sys_ioctl+0x92 ([kernel.kallsyms]) do_syscall_64+0x3a ([kernel.kallsyms]) entry_SYSCALL_64_after_hwframe+0x63 ([kernel.kallsyms]) __GI___ioctl+0x7 (/lib/x86_64-linux-gnu/libc-2.23.so)
The sequence of deadlock is:
1. Thread B calls rtnl_lock().
2. Thread A starts to run and calls rtnl_lock() from within ath11k_regd_update_work(), then enters wait state because the lock is owned by thread B.
3. Thread B continues to run and tries to call cancel_work_sync(&ar->regd_update_work), but thread A is in ath11k_regd_update_work() waiting for rtnl_lock(). So cancel_work_sync() forever waits for ath11k_regd_update_work() to finish and we have a deadlock.
Fix this by switching from using regulatory_set_wiphy_regd_sync() to regulatory_set_wiphy_regd(). Now cfg80211 will schedule another workqueue which handles the locking on it's own. So the ath11k workqueue can simply exit without taking any locks, avoiding the deadlock.
Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3
Cc: stable@vger.kernel.org Signed-off-by: Wen Gong quic_wgong@quicinc.com [kvalo: improve commit log] Signed-off-by: Kalle Valo quic_kvalo@quicinc.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/wireless/ath/ath11k/reg.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-)
--- a/drivers/net/wireless/ath/ath11k/reg.c +++ b/drivers/net/wireless/ath/ath11k/reg.c @@ -287,11 +287,7 @@ int ath11k_regd_update(struct ath11k *ar goto err; }
- rtnl_lock(); - wiphy_lock(ar->hw->wiphy); - ret = regulatory_set_wiphy_regd_sync(ar->hw->wiphy, regd_copy); - wiphy_unlock(ar->hw->wiphy); - rtnl_unlock(); + ret = regulatory_set_wiphy_regd(ar->hw->wiphy, regd_copy);
kfree(regd_copy);