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From:   Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>
To:     Johannes Berg <johannes@sipsolutions.net>,
        Jens Axboe <axboe@kernel.dk>,
        Emmanuel Grumbach <emmanuel.grumbach@intel.com>,
        Luca Coelho <luciano.coelho@intel.com>
Cc:     "linux-wireless\@vger.kernel.org" <linux-wireless@vger.kernel.org>,
        Networking <netdev@vger.kernel.org>
Subject: Re: iwlwifi warnings in 5.5-rc1
In-Reply-To: <9727368004ceef03f72d259b0779c2cf401432e1.camel@sipsolutions.net>
References: <ceb74ea2-6a1b-4cef-8749-db21a2ee4311@kernel.dk> <9727368004ceef03f72d259b0779c2cf401432e1.camel@sipsolutions.net>
Date:   Wed, 11 Dec 2019 09:53:10 +0100
Message-ID: <878snjgs5l.fsf@toke.dk>
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Johannes Berg <johannes@sipsolutions.net> writes:

> On Tue, 2019-12-10 at 13:46 -0700, Jens Axboe wrote:
>> Hi,
>>=20
>> Since the GRO issue got fixed, iwlwifi has worked fine for me.
>> However, on every boot, I get some warnings:
>>=20
>> ------------[ cut here ]------------
>> STA b4:75:0e:99:1f:e0 AC 2 txq pending airtime underflow: 4294967088, 20=
8
>
> Yeah, we've seen a few reports of this.

FWIW I've tried reproducing but I don't get the error with the 8265 /
8275 chip in my laptop. I've thought about sending a patch for mac80211
to just clear the tx_time_est field after calling
ieee80211_sta_update_pending_airtime() - that should prevent any errors
from double-reporting of skbs (which is what I'm guessing is going on
here). However, it kinda feels like a band-aid so I'd much rather figure
out why this particular driver/device combo cause this :)

> I guess I kinda feel responsible for this since I merged the AQL work,
> I'll take a look as soon as I can.

Sounds good, thanks!

-Toke