netdev - Re: [PATCH net-next 01/15] net: dsa: provide an option for drivers to always receive bridge VLANs

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Message-ID: <20200511120509.GS1551@shell.armlinux.org.uk>
Date:   Mon, 11 May 2020 13:05:09 +0100
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        netdev <netdev@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next 01/15] net: dsa: provide an option for drivers
 to always receive bridge VLANs

On Mon, May 11, 2020 at 02:59:12PM +0300, Vladimir Oltean wrote:
> On Mon, 11 May 2020 at 14:54, Russell King - ARM Linux admin
> <linux@...linux.org.uk> wrote:
> >
> > On Mon, May 11, 2020 at 02:40:29PM +0300, Vladimir Oltean wrote:
> > > On Mon, 11 May 2020 at 14:38, Russell King - ARM Linux admin
> > > <linux@...linux.org.uk> wrote:
> > > >
> > > > On Sun, May 10, 2020 at 07:42:41PM +0300, Vladimir Oltean wrote:
> > > > > From: Russell King <rmk+kernel@...linux.org.uk>
> > > > >
> > > > > DSA assumes that a bridge which has vlan filtering disabled is not
> > > > > vlan aware, and ignores all vlan configuration. However, the kernel
> > > > > software bridge code allows configuration in this state.
> > > > >
> > > > > This causes the kernel's idea of the bridge vlan state and the
> > > > > hardware state to disagree, so "bridge vlan show" indicates a correct
> > > > > configuration but the hardware lacks all configuration. Even worse,
> > > > > enabling vlan filtering on a DSA bridge immediately blocks all traffic
> > > > > which, given the output of "bridge vlan show", is very confusing.
> > > > >
> > > > > Provide an option that drivers can set to indicate they want to receive
> > > > > vlan configuration even when vlan filtering is disabled. At the very
> > > > > least, this is safe for Marvell DSA bridges, which do not look up
> > > > > ingress traffic in the VTU if the port is in 8021Q disabled state. It is
> > > > > also safe for the Ocelot switch family. Whether this change is suitable
> > > > > for all DSA bridges is not known.
> > > > >
> > > > > Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
> > > > > Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
> > > >
> > > > This patch was NAK'd because of objections to the "vlan_bridge_vtu"
> > > > name.  Unfortunately, this means that the bug for Marvell switches
> > > > remains unfixed to this day.
> > > >
> > >
> > > How about "accept_vlan_while_unaware"?
> >
> > It's up to DSA maintainers.
> >
> > However, I find that rather confusing. What's "unaware"? The point of
> > this boolean is to program the vlan tables while vlan filtering is
> > disabled. "accept_vlan_while_vlan_filtering_disabled" is way too long.
> >
> 
> Considering the VLAN filtering modes as "disabled", "check",
> "fallback" and "secure", I think a slight improvement over your
> wording might be "install_vlans_while_disabled". I hope that is not
> confusing and also not too long.

Well, it's not only about "installing" vlans, but also about removing
them as well.  "configure_vlans_while_disabled" would probably work
better.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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