ath10k: avoid possible deadlock with scan timeout
This should prevent deadlock predicted by the following splat: ====================================================== [ INFO: possible circular locking dependency detected ] 3.17.0-wl-ath+ #67 Not tainted ------------------------------------------------------- kworker/u32:1/7230 is trying to acquire lock: (&ar->conf_mutex){+.+.+.}, at: [<ffffffffa040a57d>] ath10k_scan_timeout_work+0x2d/0x50 [ath10k_core] but task is already holding lock: ((&(&ar->scan.timeout)->work)){+.+...}, at: [<ffffffff8106dae1>] process_one_work+0x151/0x470 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 ((&(&ar->scan.timeout)->work)){+.+...}: [<ffffffff810a12e5>] lock_acquire+0x85/0x100 [<ffffffff8106cb4d>] flush_work+0x3d/0x270 [<ffffffff8106e49d>] __cancel_work_timer+0x7d/0x110 [<ffffffff8106e543>] cancel_delayed_work_sync+0x13/0x20 [<ffffffffa0409f16>] ath10k_cancel_remain_on_channel+0x36/0x60 [ath10k_core] [<ffffffffa028c75c>] ieee80211_cancel_roc+0x1cc/0x2f0 [mac80211] [<ffffffffa028c8a2>] ieee80211_mgmt_tx_cancel_wait+0x22/0x30 [mac80211] [<ffffffffa0132288>] nl80211_tx_mgmt_cancel_wait+0xa8/0x130 [cfg80211] [<ffffffff816654a5>] genl_family_rcv_msg+0x1a5/0x3c0 [<ffffffff81665749>] genl_rcv_msg+0x89/0xc0 [<ffffffff81664e91>] netlink_rcv_skb+0xb1/0xc0 [<ffffffff816650bc>] genl_rcv+0x2c/0x40 [<ffffffff8166474d>] netlink_unicast+0x18d/0x200 [<ffffffff81664add>] netlink_sendmsg+0x31d/0x430 [<ffffffff8161a9ac>] sock_sendmsg+0x9c/0xd0 [<ffffffff8161b469>] ___sys_sendmsg+0x389/0x3a0 [<ffffffff8161bed9>] __sys_sendmsg+0x49/0x90 [<ffffffff8161bf32>] SyS_sendmsg+0x12/0x20 [<ffffffff8174c456>] system_call_fastpath+0x1a/0x1f -> #0 (&ar->conf_mutex){+.+.+.}: [<ffffffff810a0bde>] __lock_acquire+0x1b6e/0x1ce0 [<ffffffff810a12e5>] lock_acquire+0x85/0x100 [<ffffffff817491eb>] mutex_lock_nested+0x4b/0x370 [<ffffffffa040a57d>] ath10k_scan_timeout_work+0x2d/0x50 [ath10k_core] [<ffffffff8106db41>] process_one_work+0x1b1/0x470 [<ffffffff8106df63>] worker_thread+0x123/0x460 [<ffffffff81073f34>] kthread+0xe4/0x100 [<ffffffff8174c3ac>] ret_from_fork+0x7c/0xb0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((&(&ar->scan.timeout)->work)); lock(&ar->conf_mutex); lock((&(&ar->scan.timeout)->work)); lock(&ar->conf_mutex); *** DEADLOCK *** Reported-by: NMarek Puzyniak <marek.puzyniak@tieto.com> Signed-off-by: NMichal Kazior <michal.kazior@tieto.com> Signed-off-by: NKalle Valo <kvalo@qca.qualcomm.com>
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