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Subject: Re: [PATCH] wifi: ath11k: Fix deadlock during WoWLAN suspend
From:   Kalle Valo <kvalo@kernel.org>
In-Reply-To: <20220919021435.2459-1-quic_bqiang@quicinc.com>
References: <20220919021435.2459-1-quic_bqiang@quicinc.com>
To:     Baochen Qiang <quic_bqiang@quicinc.com>
Cc:     <ath11k@lists.infradead.org>, <linux-wireless@vger.kernel.org>
User-Agent: pwcli/0.1.1-git (https://github.com/kvalo/pwcli/) Python/3.7.3
Message-ID: <166418526848.13691.14908006715046928554.kvalo@kernel.org>
Date:   Mon, 26 Sep 2022 09:41:10 +0000 (UTC)
Precedence: bulk

Baochen Qiang <quic_bqiang@quicinc.com> wrote:

> We are seeing system hangs during WoWLAN suspend, and get below
> two stacks:
> 
> Stack1:
> [ffffb02cc1557b20] __schedule at ffffffff8bb10860
> [ffffb02cc1557ba8] schedule at ffffffff8bb10f24
> [ffffb02cc1557bb8] schedule_timeout at ffffffff8bb16d88
> [ffffb02cc1557c30] wait_for_completion at ffffffff8bb11778
> [ffffb02cc1557c78] __flush_work at ffffffff8b0b30cd
> [ffffb02cc1557cf0] __cancel_work_timer at ffffffff8b0b33ad
> [ffffb02cc1557d60] ath11k_mac_drain_tx at ffffffffc0c1f0ca [ath11k]
> [ffffb02cc1557d70] ath11k_wow_op_suspend at ffffffffc0c5201e [ath11k]
> [ffffb02cc1557da8] __ieee80211_suspend at ffffffffc11e2bd3 [mac80211]
> [ffffb02cc1557dd8] wiphy_suspend at ffffffffc0f901ac [cfg80211]
> [ffffb02cc1557e08] dpm_run_callback at ffffffff8b75118a
> [ffffb02cc1557e38] __device_suspend at ffffffff8b751630
> [ffffb02cc1557e70] async_suspend at ffffffff8b7519ea
> [ffffb02cc1557e88] async_run_entry_fn at ffffffff8b0bf4ce
> [ffffb02cc1557ea8] process_one_work at ffffffff8b0b1a24
> [ffffb02cc1557ee0] worker_thread at ffffffff8b0b1c4a
> [ffffb02cc1557f18] kthread at ffffffff8b0b9cb8
> [ffffb02cc1557f50] ret_from_fork at ffffffff8b001d32
> 
> Stack2:
> [ffffb02cc00b7d18] __schedule at ffffffff8bb10860
> [ffffb02cc00b7da0] schedule at ffffffff8bb10f24
> [ffffb02cc00b7db0] schedule_preempt_disabled at ffffffff8bb112b4
> [ffffb02cc00b7db8] __mutex_lock at ffffffff8bb127ea
> [ffffb02cc00b7e38] ath11k_mgmt_over_wmi_tx_work at ffffffffc0c1aa44 [ath11k]
> [ffffb02cc00b7ea8] process_one_work at ffffffff8b0b1a24
> [ffffb02cc00b7ee0] worker_thread at ffffffff8b0b1c4a
> [ffffb02cc00b7f18] kthread at ffffffff8b0b9cb8
> [ffffb02cc00b7f50] ret_from_fork at ffffffff8b001d32
> 
> From the first stack, ath11k_mac_drain_tx calls
> cancel_work_sync(&ar->wmi_mgmt_tx_work) and waits all packets to be sent
> out or dropped. However, we find from Stack2 that this work item is blocked
> because ar->conf_mutex is already held by ath11k_wow_op_suspend.
> 
> Fix this issue by moving ath11k_mac_wait_tx_complete to the start of
> ath11k_wow_op_suspend where ar->conf_mutex has not been acquired. And
> this change also makes the logic in ath11k_wow_op_suspend match the
> logic in ath11k_mac_op_start and ath11k_mac_op_stop.
> 
> Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3
> 
> Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
> Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>

Patch applied to ath-next branch of ath.git, thanks.

d78c8b7131dc wifi: ath11k: Fix deadlock during WoWLAN suspend

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20220919021435.2459-1-quic_bqiang@quicinc.com/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches