netdev - RE: v5.5-rc1 and beyond insta-kills some Comcast wifi routers

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Message-ID: <c185b1f27e4a4b66941b50697dba006c@realtek.com>
Date:   Wed, 4 Mar 2020 10:41:42 +0000
From:   Tony Chuang <yhchuang@...ltek.com>
To:     "Mancini, Jason" <Jason.Mancini@....com>,
        Kalle Valo <kvalo@...eaurora.org>,
        Randy Dunlap <rdunlap@...radead.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>
Subject: RE: v5.5-rc1 and beyond insta-kills some Comcast wifi routers

> [AMD Official Use Only - Internal Distribution Only]
> 
> I tested Kalle's patch.  Laptop connects via 5GHz band by default.  Comcast
> router still
> crashed in a hurry.  I blocked (via NM.conf) the 5GHz mac of the router, and
> rebooted
> the laptop. Checked that the router was using 2.4 for the laptop.  Still hung
> the router!
> 
> What I've done temporarily is change the unlimited return value from 0 to
> 4000.
> Somewhere around 5325 the Comcast router gets cranky/weird, and at 5350
> it is
> resetting the wifi stack (without resetting the entire router).
> 
> So there's no boot time flag to turn the feature off currently?
> 

Unfortunately, no, there's no flag to turn off this.

But, from your experiments, if you applied that patch,
("rtw88: disable TX-AMSDU on 2.4G band") connect to AP on 2.4G, and still crash
the Comcast AP, then it looks like it's not TX-AMSDU to be blamed.

Assume the return value you mentioned is max_rc_amsdu_len, if you always
return 1, it will just disable all of the AMSDU process.
You can try it, and to see if sending AMSDU will crash the router or not.

Yen-Hsuan