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From: "Nicolas Escande" <nico.escande@gmail.com>
To: <nbd@nbd.name>
Cc: <linux-wireless@vger.kernel.org>
Subject: [regression] STP on 80211s is broken in 6.4-rc4
Date: Tue, 06 Jun 2023 12:55:57 +0200	[thread overview]
Message-ID: <CT5GNZSK28AI.2K6M69OXM9RW5@syracuse> (raw)

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 especially
the recent improvements you made for mesh fast RX/TX & cross vendor AMSDU compat

We upgraded our kernel from an older (5.15) to a newer 6.4. The problem is STP 
doesn't work anymore and alas we use it for now (for the better or worse).

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 amsdu
 - 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 packet
   this makes llc_rcv() discard the frames & breaks STP

From bisecting the culprit seems to be 986e43b19ae9176093da35e0a844e65c8bf9ede7
(wifi: mac80211: fix receiving A-MSDU frames on mesh interfaces)

I guess that your changes to handle both ampdu subframes & normal frames in the
same datapath ends up putting a wrong skb->len for STP (multicast) frames ?
Honestly I don't understand enough of the 80211 internals & spec to pinpoint 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 something...

Anyway I'm happy to provide more info or try anything you throw at me.

Thanks,

---
Nicolas E.

             reply	other threads:[~2023-06-06 10:57 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-06 10:55 Nicolas Escande [this message]
2023-06-10  6:44 ` [regression] STP on 80211s is broken in 6.4-rc4 Bagas Sanjaya
2023-06-15 12:54   ` Linux regression tracking (Thorsten Leemhuis)
2023-06-16  7:45     ` Nicolas Escande
2023-06-16  9:25       ` Linux regression tracking (Thorsten Leemhuis)
2023-06-16 12:17         ` Bagas Sanjaya
2023-06-16 12:33           ` Linux regression tracking (Thorsten Leemhuis)
2023-07-10 11:32       ` Linux regression tracking (Thorsten Leemhuis)
2023-07-10 16:50         ` Nicolas Escande
2023-07-11 11:12           ` Felix Fietkau
2023-07-11 12:15             ` Nicolas Escande

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