linux-kernel - Re: [PATCH net v2] net: mscc: ocelot: Fix multicast to the CPU port

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Message-ID: <20210120090054.12d56482@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Wed, 20 Jan 2021 09:00:54 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Vladimir Oltean <vladimir.oltean@....com>,
        "Bedel, Alban" <alban.bedel@...q.com>
Cc:     Claudiu Manoil <claudiu.manoil@....com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        "UNGLinuxDriver@...rochip.com" <UNGLinuxDriver@...rochip.com>,
        "David S. Miller" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net v2] net: mscc: ocelot: Fix multicast to the CPU port

On Tue, 19 Jan 2021 16:46:01 +0000 Vladimir Oltean wrote:
> On Tue, Jan 19, 2021 at 03:06:38PM +0100, Alban Bedel wrote:
> > Multicast entries in the MAC table use the high bits of the MAC
> > address to encode the ports that should get the packets. But this port
> > mask does not work for the CPU port, to receive these packets on the
> > CPU port the MAC_CPU_COPY flag must be set.
> > 
> > Because of this IPv6 was effectively not working because neighbor
> > solicitations were never received. This was not apparent before commit
> > 9403c158 (net: mscc: ocelot: support IPv4, IPv6 and plain Ethernet mdb
> > entries) as the IPv6 entries were broken so all incoming IPv6
> > multicast was then treated as unknown and flooded on all ports.
> > 
> > To fix this problem rework the ocelot_mact_learn() to set the
> > MAC_CPU_COPY flag when a multicast entry that target the CPU port is
> > added. For this we have to read back the ports endcoded in the pseudo
> > MAC address by the caller. It is not a very nice design but that avoid
> > changing the callers and should make backporting easier.
> > 
> > Signed-off-by: Alban Bedel <alban.bedel@...q.com>
> > Fixes: 9403c158b872 ("net: mscc: ocelot: support IPv4, IPv6 and plain Ethernet mdb entries")
> > 
> > ---  
> 
> Reviewed-by: Vladimir Oltean <vladimir.oltean@....com>
> Tested-by: Vladimir Oltean <vladimir.oltean@....com>

Applied, thanks!