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Message-ID: <300bf0146db6c0d5890699b3911d35174d28c9c0.camel@sipsolutions.net>
Subject: Re: [PATCH v6 3/4] mac80211: Implement Airtime-based Queue Limit
 (AQL)
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Toke =?ISO-8859-1?Q?H=F8iland-J=F8rgensen?= <toke@redhat.com>
Cc:     linux-wireless@vger.kernel.org,
        make-wifi-fast@lists.bufferbloat.net, ath10k@lists.infradead.org,
        John Crispin <john@phrozen.org>,
        Lorenzo Bianconi <lorenzo@kernel.org>,
        Felix Fietkau <nbd@nbd.name>, Kan Yan <kyan@google.com>,
        Rajkumar Manoharan <rmanohar@codeaurora.org>,
        Kevin Hayes <kevinhayes@google.com>
Date:   Fri, 08 Nov 2019 12:17:22 +0100
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On Fri, 2019-11-08 at 12:10 +0100, Toke Høiland-Jørgensen wrote:

> Right, bugger. I was thinking maybe there's a case where skbs can be
> cloned (and retain the tx_time_est field) and then released twice? 

They could be cloned, but I don't see how that'd be while *inside* the
stack and then they get reported twice - unless the driver did something
like that?

I mean, TCP surely does that for example, but it's before we even get to
mac80211.

> Or
> maybe somewhere that steps on the skb->cb field in some other way?
> Couldn't find anything obvious on a first perusal of the TX path code,
> but maybe you could think of something?

No, sorry. But I also didn't actually look at the driver at all.

> Otherwise I guess we'll be forced to go and do some actual,
> old-fashioned debugging ;)

:)

johannes