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Subject: Re: [PATCH v2] wifi: ath12k: fix potential wmi_mgmt_tx_queue race
 condition
From:   Kalle Valo <kvalo@kernel.org>
In-Reply-To: <20230419095758.19998-1-quic_rgnanase@quicinc.com>
References: <20230419095758.19998-1-quic_rgnanase@quicinc.com>
To:     Ramya Gnanasekar <quic_rgnanase@quicinc.com>
Cc:     ath12k@lists.infradead.org, linux-wireless@vger.kernel.org,
        Karthik M <quic_karm@quicinc.com>,
        Ramya Gnanasekar <quic_rgnanase@quicinc.com>
User-Agent: pwcli/0.1.1-git (https://github.com/kvalo/pwcli/) Python/3.7.3
Message-ID: <168329151051.30600.2331645235698390250.kvalo@kernel.org>
Date:   Fri,  5 May 2023 12:58:32 +0000 (UTC)
Precedence: bulk

Ramya Gnanasekar <quic_rgnanase@quicinc.com> wrote:

> During stress test with maximum VAPs and peer connected, below warning
> is seen:
> 
> [ 1079.110967] ath12k_pci 0004:01:00.0: mgmt tx queue is full
> [ 1079.117708] ath12k_pci 0004:01:00.0: failed to queue management frame -28
> [ 1079.123191] ath12k_pci 0004:01:00.0: mgmt tx queue is full
> [ 1079.129960] ath12k_pci 0004:01:00.0: failed to queue management frame -28
> [ 1079.135641] ath12k_pci 0004:01:00.0: mgmt tx queue is full
> 
> This is caused by potential race condition while accessing skb_queue_len().
> When ath12k_mgmt_over_wmi_tx_work() and ath12k_mac_mgmt_tx() is called concurrently,
> then skb_queue_len() might fetch list length which is modified by skb_queue_tail()
> or skb_dequeue().
> 
> Replace skb_queue_len() with skb_queue_len_lockless() which will
> prevent concurrent modified access using READ_ONCE(). And also use '>=',
> in case we queue a few SKBs simultaneously.
> 
> Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.0.1-00029-QCAHKSWPL_SILICONZ-1
> 
> Signed-off-by: Karthik M <quic_karm@quicinc.com>
> Signed-off-by: Ramya Gnanasekar <quic_rgnanase@quicinc.com>
> Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>

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

e995f3f602a3 wifi: ath12k: fix potential wmi_mgmt_tx_queue race condition

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20230419095758.19998-1-quic_rgnanase@quicinc.com/

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