linux-kernel - Re: [PATCH net] net: dsa: fix VLAN 0 filter imbalance when toggling filtering

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Message-ID: <20250428090244.phg3xijxhhtczkvk@skbuf>
Date: Mon, 28 Apr 2025 12:02:44 +0300
From: Vladimir Oltean <olteanv@...il.com>
To: Jonas Gorski <jonas.gorski@...il.com>
Cc: Paolo Abeni <pabeni@...hat.com>, Andrew Lunn <andrew@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Simon Horman <horms@...nel.org>,
	Florian Fainelli <f.fainelli@...il.com>,
	Vladimir Oltean <vladimir.oltean@....com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] net: dsa: fix VLAN 0 filter imbalance when toggling
 filtering

On Sat, Apr 26, 2025 at 05:48:26PM +0200, Jonas Gorski wrote:
> It does need a lot more fixes on top of that. With this patch applied:
> 
> TEST: Reception of 802.1p-tagged traffic                            [ OK ]
> TEST: Dropping of untagged and 802.1p-tagged traffic with no PVID   [FAIL]
>         802.1p-tagged reception succeeded, but should have failed
> 
> The latter is no surprise, since b53 does not handle non filtering
> bridges correctly, or toggling filtering at runtime.
> 
> I fixed most issues I found in b53 and it now succeeds in WIP code I
> have (and most other tests from there).
> 
> One thing I struggled a bit is that the second test tests four
> different scenarios, but only has one generic failure message, so a
> failure does not tell which of the four setups failed.
> 
> The issues I fixed so far locally:
> 
> 1. b53 programs the vlan table based on bridge vlans regardless if
> filtering is on or not
> 2. b53 allows vlan 0 to be modified from
> dsa_switch_ops::port_vlan_{add,remove} for bridged ports
> 3. b53 adds vlan 0 to a port when it leaves a bridge, but does not
> remove it on join
> 4. b53 does not handle switching a vlan from pvid to non-pvid
> 5. stp (and other reserved multicast) requires a PVID vlan.
> 
> This makes especially non-filtering bridges not work as expected, or
> the switch in any way after adding and then removing a filtering
> bridge.

I'll admit that I'm not very familiar with the b53 driver and that my
attention span has been quite short (and the passage of the weekend has
not helped). Please post patches explaining clearly where we are and
I'll try to follow along.