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Subject: Re: [PATCH] ath11k: fix a locking bug in ath11k_mac_op_start()
To:     Dan Carpenter <dan.carpenter@oracle.com>,
        Kalle Valo <kvalo@codeaurora.org>
Cc:     Carl Huang <cjhuang@codeaurora.org>, ath11k@lists.infradead.org,
        linux-wireless@vger.kernel.org, kernel-janitors@vger.kernel.org
References: <YBfy+zc3XkiyIe6t@mwanda>
From:   Peter Oh <peter.oh@eero.com>
Message-ID: <896a68dd-02ec-4fe3-3fbf-ec1bd2decefe@eero.com>
Date:   Mon, 1 Feb 2021 13:47:27 -0800
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On 2/1/21 4:24 AM, Dan Carpenter wrote:
> This error path leads to a Smatch warning:
>
>      drivers/net/wireless/ath/ath11k/mac.c:4269 ath11k_mac_op_start()
>      error: double unlocked '&ar->conf_mutex' (orig line 4251)
>
> We're not holding the lock when we do the "goto err;" so it leads to a
> double unlock.  We should hold the lock because the error path sets
> "ar->state" so the right fix is to take the lock before doing the goto.
>
> Fixes: c83c500b55b6 ("ath11k: enable idle power save mode")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>   drivers/net/wireless/ath/ath11k/mac.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
> index c1608f64ea95..12e981e9e3d7 100644
> --- a/drivers/net/wireless/ath/ath11k/mac.c
> +++ b/drivers/net/wireless/ath/ath11k/mac.c
> @@ -4259,6 +4259,7 @@ static int ath11k_mac_op_start(struct ieee80211_hw *hw)
>   						1, pdev->pdev_id);
>   		if (ret) {
>   			ath11k_err(ab, "failed to enable idle ps: %d\n", ret);
> +			mutex_lock(&ar->conf_mutex);
>   			goto err;
>   		}
>   	}
It seems moving idle_ps condition in between ath11k_wmi_pdev_lro_cfg() 
and mutex_unlock()
  is a better way in this case.

Thanks,
Peter