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From: Ping-Ke Shih <pkshih@realtek.com>
To: Bitterblue Smith <rtl8821cerfe2@gmail.com>,
        "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
CC: Ping-Ke Shih <pkshih@realtek.com>, Sascha Hauer <sha@pengutronix.de>
Subject: Re: [PATCH] wifi: rtw88: usb: Fix disconnection after beacon loss
In-Reply-To: <ecbf0601-810d-4609-b8fc-8b0e38d2948d@gmail.com>
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Message-ID: <5fc4ad6b-5af8-469b-9665-d41ddb6d465f@RTEXMBS04.realtek.com.tw>
Date: Thu, 9 May 2024 14:23:25 +0800

Bitterblue Smith <rtl8821cerfe2@gmail.com> wrote:

> When there is beacon loss, for example due to unrelated Bluetooth
> devices transmitting music nearby, the wifi connection dies soon
> after the first beacon loss message:
> 
> Apr 28 20:47:14 ideapad2 wpa_supplicant[1161]: wlp3s0f3u4:
>  CTRL-EVENT-BEACON-LOSS
> Apr 28 20:47:15 ideapad2 wpa_supplicant[1161]: wlp3s0f3u4:
>  CTRL-EVENT-DISCONNECTED bssid=... reason=4 locally_generated=1
> 
> Apr 28 20:47:24 ideapad2 wpa_supplicant[1161]: wlp3s0f3u4:
>  CTRL-EVENT-BEACON-LOSS
> Apr 28 20:47:25 ideapad2 wpa_supplicant[1161]: wlp3s0f3u4:
>  CTRL-EVENT-DISCONNECTED bssid=... reason=4 locally_generated=1
> 
> Apr 28 20:47:34 ideapad2 wpa_supplicant[1161]: wlp3s0f3u4:
>  CTRL-EVENT-BEACON-LOSS
> Apr 28 20:47:35 ideapad2 wpa_supplicant[1161]: wlp3s0f3u4:
>  CTRL-EVENT-DISCONNECTED bssid=... reason=4 locally_generated=1
> 
> When the beacon loss happens, mac80211 makes rtw88 transmit a QOS
> NULL frame and asks to confirm the ACK status. Even though rtw88
> confirms to mac80211 that the QOS NULL was transmitted successfully,
> the connection still dies. This is because rtw88 is handing the QOS
> NULL back to mac80211 with skb->data pointing to the headroom (the
> TX descriptor) instead of ieee80211_hdr.
> 
> Fix the disconnection by moving skb->data to the correct position
> before ieee80211_tx_status_irqsafe().
> 
> The problem was observed with RTL8811AU (TP-Link Archer T2U Nano)
> and the potential future rtw88_8821au driver. Also tested with
> RTL8811CU (Tenda U9).
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>

1 patch(es) applied to rtw-next branch of rtw.git, thanks.

28818b4d871b wifi: rtw88: usb: Fix disconnection after beacon loss

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https://github.com/pkshih/rtw.git