Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Mime-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain; charset=UTF-8
Date:   Fri, 16 Jun 2023 09:45:57 +0200
From:   "Nicolas Escande" <nico.escande@gmail.com>
To:     "Linux regressions mailing list" <regressions@lists.linux.dev>,
        "Bagas Sanjaya" <bagasdotme@gmail.com>, <nbd@nbd.name>,
        =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= <toke@toke.dk>,
        "Kalle Valo" <kvalo@kernel.org>,
        "Johannes Berg" <johannes.berg@intel.com>
Cc:     <linux-wireless@vger.kernel.org>
Subject: Re: [regression] STP on 80211s is broken in 6.4-rc4
Message-Id: <CTDWJJDKSYYD.XBG1CAZB3A5W@syracuse>
References: <CT5GNZSK28AI.2K6M69OXM9RW5@syracuse>
 <ZIQbs0wqdRh7c0Kx@debian.me>
 <a9d02800-2cd6-a27b-7998-4c97cf2eb692@leemhuis.info>
In-Reply-To: <a9d02800-2cd6-a27b-7998-4c97cf2eb692@leemhuis.info>
Precedence: bulk

On Thu Jun 15, 2023 at 2:54 PM CEST, Linux regression tracking (Thorsten Le=
emhuis) wrote:
> On 10.06.23 08:44, Bagas Sanjaya wrote:
> > On Tue, Jun 06, 2023 at 12:55:57PM +0200, Nicolas Escande wrote:
> >> Hello Felix,
> >>
> >> As user of the mesh part of mac80211 on multiple products at work let =
me say
> >> thank you for all the work you do on wifi, especially on 80211s, and e=
specially
> >> the recent improvements you made for mesh fast RX/TX & cross vendor AM=
SDU compat
> >>
> >> We upgraded our kernel from an older (5.15) to a newer 6.4. The proble=
m is STP=20
> >> doesn't work anymore and alas we use it for now (for the better or wor=
se).
> >>
> >> What I gathered so far from my setup:
> >>  - we use ath9k & ath10k
> >>  - in my case STP frames are received as regular packet and not as ams=
du
> >>  - the received packets have a wrong length of 44 in tcpdump
> >>    (instead of 38 with our previous kernel)
> >>  - llc_fixup_skb() tries to pull some 41 bytes out of a 35 bytes packe=
t
> >>    this makes llc_rcv() discard the frames & breaks STP
> >>
> >> >From bisecting the culprit seems to be 986e43b19ae9176093da35e0a844e6=
5c8bf9ede7
> >> (wifi: mac80211: fix receiving A-MSDU frames on mesh interfaces)
> >>
> >> I guess that your changes to handle both ampdu subframes & normal fram=
es in the
> >> same datapath ends up putting a wrong skb->len for STP (multicast) fra=
mes ?
> >> Honestly I don't understand enough of the 80211 internals & spec to pi=
npoint the
> >> exact problem.
> >>
> >> It seems this change was already in the 6.3 kernel so I guess someone =
should
> >> have seen it before (but I didn't find anything..) ? Maybe I missed so=
mething...
> >>
> >> Anyway I'm happy to provide more info or try anything you throw at me.
> >>
> >=20
> > Thanks for the regression report. I'm adding it to regzbot:
> >=20
> > (Felix: it looks like this regression is introcued by a commit authored=
 by you.
> > Would you like to take a look on it?)
> >=20
> > #regzbot ^introduced: 986e43b19ae917
>
> Hmmm, Felix did not reply. But let's ignore that for now.

I haven't seen mails from felix on the list for a few days, I'm guessing he=
's
unavailable for now but I'll hapilly wait.

>
> Nicolas, I noticed there are a few patches in next that refer to the
> culprit. Might be worth giving this series a try:
>
> https://lore.kernel.org/all/20230314095956.62085-1-nbd@nbd.name/

Well this series already landed in 6.4 and that is the version I did my ini=
tial
testing with. So no luck there.

>
> Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
> --
> Everything you wanna know about Linux kernel regression tracking:
> https://linux-regtracking.leemhuis.info/about/#tldr
> If I did something stupid, please tell me, as explained on that page.