linux-kernel - Re: [PATCH] net: bridge: Allow bridge to joing multicast groups

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Message-ID: <20190730100416.GA13250@splinter>
Date:   Tue, 30 Jul 2019 13:04:16 +0300
From:   Ido Schimmel <idosch@...sch.org>
To:     "Allan W. Nielsen" <allan.nielsen@...rochip.com>
Cc:     Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        Horatiu Vultur <horatiu.vultur@...rochip.com>,
        roopa@...ulusnetworks.com, davem@...emloft.net,
        bridge@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: bridge: Allow bridge to joing multicast groups

On Tue, Jul 30, 2019 at 10:30:28AM +0200, Allan W. Nielsen wrote:
> The 07/30/2019 10:06, Ido Schimmel wrote:
> > As a bonus, existing drivers could benefit from it, as MDB entries are already
> > notified by MAC.
> Not sure I follow. When FDB entries are added, it also generates notification
> events.

I meant the switchdev notification sent to drivers:

/* SWITCHDEV_OBJ_ID_PORT_MDB */
struct switchdev_obj_port_mdb {
	struct switchdev_obj obj;
	unsigned char addr[ETH_ALEN];
	u16 vid;
};

By extending MDB entries to also be keyed by MAC you basically get a lot
of things for free without duplicating the same code for multicast FDBs.

AFAICS, then only change in the fast path is in br_mdb_get() where you
need to use DMAC as key in case Ethertype is not IPv4/IPv6.