linux-kernel - Re: [PATCH net-next v2] net: dsa: b53: Do not force CPU to be always tagged

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Date:   Tue, 8 Jun 2021 14:26:23 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     netdev@...r.kernel.org
Cc:     mnhagan88@...il.com, Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next v2] net: dsa: b53: Do not force CPU to be always
 tagged



On 6/8/2021 2:22 PM, Florian Fainelli wrote:
> Commit ca8931948344 ("net: dsa: b53: Keep CPU port as tagged in all
> VLANs") forced the CPU port to be always tagged in any VLAN membership.
> This was necessary back then because we did not support Broadcom tags
> for all configurations so the only way to differentiate tagged and
> untagged traffic while DSA_TAG_PROTO_NONE was used was to force the CPU
> port into being always tagged.
> 
> With most configurations enabling Broadcom tags, especially after
> 8fab459e69ab ("net: dsa: b53: Enable Broadcom tags for 531x5/539x
> families") we do not need to apply this unconditional force tagging of
> the CPU port in all VLANs.
> 
> A helper function is introduced to faciliate the encapsulation of the
> specific condition requiring the CPU port to be tagged in all VLANs and
> the dsa_switch_ops::untag_bridge_pvid boolean is moved to when
> dsa_switch_ops::setup is called when we have already determined the
> tagging protocol we will be using.
> 
> Reported-by: Matthew Hagan <mnhagan88@...il.com>
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> ---

Matthew, here is a tcpdump capture showing that there is no VLAN 0 tag
being added, unlike before:

00:00:42.191113 b8:ac:6f:80:af:7e (oui Unknown) > 00:10:18:cd:c9:c2 (oui
Unknown), BRCM tag OP: EG, CID: 0, RC: exception, TC: 0, port: 0,
ethertype IPv4 (0x0800), length 102: (tos 0x0, ttl 64, id 25041, offset
0, flags [none], proto ICMP (1), length 84)
    192.168.1.254 > 192.168.1.10: ICMP echo reply, id 1543, seq 12,
length 64
        0x0000:  0010 18cd c9c2 b8ac 6f80 af7e 0000 2000  ........o..~....
        0x0010:  0800 4500 0054 61d1 0000 4001 947f c0a8  ..E..Ta...@.....
        0x0020:  01fe c0a8 010a 0000 4522 0607 000c 31c8  ........E"....1.
        0x0030:  8302 0000 0000 0000 0000 0000 0000 0000  ................
        0x0040:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x0050:  0000 0000 0000 0000 0000 0000 0000 0000  ................
        0x0060:  0000 0000 0000

Let me know how this patch goes.
-- 
Florian