netdev - Re: [PATCH v2 net 4/4] net: dsa: mv88e6xxx: Limit rsvd2cpu policy to user ports on 6393X

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Message-ID: <20241219141431.qaosfbhlzk2hcbca@skbuf>
Date: Thu, 19 Dec 2024 16:14:31 +0200
From: Vladimir Oltean <olteanv@...il.com>
To: Tobias Waldekranz <tobias@...dekranz.com>
Cc: davem@...emloft.net, kuba@...nel.org, andrew@...n.ch,
	f.fainelli@...il.com, netdev@...r.kernel.org, linux@...linux.org.uk,
	chris.packham@...iedtelesis.co.nz, pabeni@...hat.com
Subject: Re: [PATCH v2 net 4/4] net: dsa: mv88e6xxx: Limit rsvd2cpu policy to
 user ports on 6393X

On Thu, Dec 19, 2024 at 04:05:41PM +0200, Vladimir Oltean wrote:
> On Thu, Dec 19, 2024 at 01:30:43PM +0100, Tobias Waldekranz wrote:
> > For packets with a DA in the IEEE reserved L2 group range, originating
> > from a CPU, forward it as normal, rather than classifying it as
> > management.
> 
> Doesn't this break STP? Must be able to inject into ports with an STP
> state other than FORWARDING. I expect that you need a DSA_CMD_FROM_CPU
> tag for that, can't do it with DSA_CMD_FORWARD.

ah, I made a stupid mistake, I though locally generated STP goes through
__br_forward().

I put a WARN_ON_ONCE(skb->protocol == htons(ETH_P_802_2)); in DSA xmit
and convinced myself that this is not the case.

[   67.115425]  br_send_bpdu+0x130/0x2a0
[   67.119187]  br_send_config_bpdu+0x12c/0x170
[   67.123559]  br_transmit_config+0x114/0x180
[   67.127842]  br_config_bpdu_generation+0x6c/0x88
[   67.132562]  br_hello_timer_expired+0x44/0x98
[   67.137022]  call_timer_fn+0xc8/0x300

Please ignore this comment.