netdev - Re: [PATCH resend net-next 2/2] net: bridge: switchdev: include local flag in FDB notifications

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Date:   Fri, 16 Apr 2021 18:22:08 +0300
From:   Ido Schimmel <idosch@...sch.org>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Ioana Ciornei <ioana.ciornei@....com>,
        Vadym Kochan <vkochan@...vell.com>,
        Taras Chornyi <tchornyi@...vell.com>,
        Jiri Pirko <jiri@...dia.com>, Ido Schimmel <idosch@...dia.com>,
        Grygorii Strashko <grygorii.strashko@...com>,
        Ivan Vecera <ivecera@...hat.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <nikolay@...dia.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-omap@...r.kernel.org,
        Vladimir Oltean <vladimir.oltean@....com>,
        Tobias Waldekranz <tobias@...dekranz.com>
Subject: Re: [PATCH resend net-next 2/2] net: bridge: switchdev: include
 local flag in FDB notifications

On Wed, Apr 14, 2021 at 07:52:56PM +0300, Vladimir Oltean wrote:
> From: Vladimir Oltean <vladimir.oltean@....com>
> 
> As explained in bugfix commit 6ab4c3117aec ("net: bridge: don't notify
> switchdev for local FDB addresses") as well as in this discussion:
> https://lore.kernel.org/netdev/20210117193009.io3nungdwuzmo5f7@skbuf/
> 
> the switchdev notifiers for FDB entries managed to have a zero-day bug,
> which was that drivers would not know what to do with local FDB entries,
> because they were not told that they are local. The bug fix was to
> simply not notify them of those addresses.
> 
> Let us now add the 'is_local' bit to bridge FDB entries, and make all
> drivers ignore these entries by their own choice.
> 
> Co-developed-by: Tobias Waldekranz <tobias@...dekranz.com>
> Signed-off-by: Tobias Waldekranz <tobias@...dekranz.com>
> Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>

Reviewed-by: Ido Schimmel <idosch@...dia.com>

One comment below

> diff --git a/net/bridge/br_switchdev.c b/net/bridge/br_switchdev.c
> index c390f84adea2..a5e601e41cb9 100644
> --- a/net/bridge/br_switchdev.c
> +++ b/net/bridge/br_switchdev.c
> @@ -114,13 +114,12 @@ br_switchdev_fdb_notify(const struct net_bridge_fdb_entry *fdb, int type)
>  		.addr = fdb->key.addr.addr,
>  		.vid = fdb->key.vlan_id,
>  		.added_by_user = test_bit(BR_FDB_ADDED_BY_USER, &fdb->flags),
> +		.is_local = test_bit(BR_FDB_LOCAL, &fdb->flags),
>  		.offloaded = test_bit(BR_FDB_OFFLOADED, &fdb->flags),
>  	};
>  
>  	if (!fdb->dst)
>  		return;

Do you plan to eventually remove this check so that entries pointing to
the bridge device itself will be notified? For example:

# bridge fdb add 00:01:02:03:04:05 dev br0 self local

> -	if (test_bit(BR_FDB_LOCAL, &fdb->flags))
> -		return;
>  
>  	switch (type) {
>  	case RTM_DELNEIGH: