netdev - Re: [PATCH net-next] net: dsa: set configure_vlan_while_not

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Message-ID: <87o8hq4qu2.fsf@kurt>
Date:   Fri, 15 Jan 2021 08:11:33 +0100
From:   Kurt Kanzenbach <kurt@...utronix.de>
To:     Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Hauke Mehrtens <hauke@...ke-m.de>,
        Woojung Huh <woojung.huh@...rochip.com>,
        UNGLinuxDriver@...rochip.com, Sean Wang <sean.wang@...iatek.com>,
        Landen Chao <Landen.Chao@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Oleksij Rempel <linux@...pel-privat.de>
Subject: Re: [PATCH net-next] net: dsa: set configure_vlan_while_not_filtering to true by default

On Thu Jan 14 2021, Vladimir Oltean wrote:
> From: Vladimir Oltean <vladimir.oltean@....com>
>
> As explained in commit 54a0ed0df496 ("net: dsa: provide an option for
> drivers to always receive bridge VLANs"), DSA has historically been
> skipping VLAN switchdev operations when the bridge wasn't in
> vlan_filtering mode, but the reason why it was doing that has never been
> clear. So the configure_vlan_while_not_filtering option is there merely
> to preserve functionality for existing drivers. It isn't some behavior
> that drivers should opt into. Ideally, when all drivers leave this flag
> set, we can delete the dsa_port_skip_vlan_configuration() function.
>
> New drivers always seem to omit setting this flag, for some reason. So
> let's reverse the logic: the DSA core sets it by default to true before
> the .setup() callback, and legacy drivers can turn it off. This way, new
> drivers get the new behavior by default, unless they explicitly set the
> flag to false, which is more obvious during review.
>
> Remove the assignment from drivers which were setting it to true, and
> add the assignment to false for the drivers that didn't previously have
> it. This way, it should be easier to see how many we have left.
>
> The following drivers: lan9303, mv88e6060 were skipped from setting this
> flag to false, because they didn't have any VLAN offload ops in the
> first place.
>
> The Broadcom Starfighter 2 driver calls the common b53_switch_alloc and
> therefore also inherits the configure_vlan_while_not_filtering=true
> behavior.
>
> Also, print a message through netlink extack every time a VLAN has been
> skipped. This is mildly annoying on purpose, so that (a) it is at least
> clear that VLANs are being skipped - the legacy behavior in itself is
> confusing, and the extack should be much more difficult to miss, unlike
> kernel logs - and (b) people have one more incentive to convert to the
> new behavior.
>
> No behavior change except for the added prints is intended at this time.
>
> $ ip link add br0 type bridge vlan_filtering 0
> $ ip link set sw0p2 master br0
> [   60.315148] br0: port 1(sw0p2) entered blocking state
> [   60.320350] br0: port 1(sw0p2) entered disabled state
> [   60.327839] device sw0p2 entered promiscuous mode
> [   60.334905] br0: port 1(sw0p2) entered blocking state
> [   60.340142] br0: port 1(sw0p2) entered forwarding state
> Warning: dsa_core: skipping configuration of VLAN. # This was the pvid
> $ bridge vlan add dev sw0p2 vid 100
> Warning: dsa_core: skipping configuration of VLAN.
>
> Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>

Reviewed-by: Kurt Kanzenbach <kurt@...utronix.de>

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