netdev - Re: [PATCH net-next 3/6] net: bridge: break if __br_mdb

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Date:   Thu, 18 May 2017 11:08:50 -0400
From:   Vivien Didelot <vivien.didelot@...oirfairelinux.com>
To:     Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        netdev@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel@...oirfairelinux.com,
        "David S. Miller" <davem@...emloft.net>,
        Stephen Hemminger <stephen@...workplumber.org>,
        "moderated list\:ETHERNET BRIDGE" <bridge@...ts.linux-foundation.org>
Subject: Re: [PATCH net-next 3/6] net: bridge: break if __br_mdb_del    fails

Hi Nikolay,

Nikolay Aleksandrov <nikolay@...ulusnetworks.com> writes:

>>   			err = __br_mdb_del(br, entry);
>> -			if (!err)
>> -				__br_mdb_notify(dev, p, entry, RTM_DELMDB);
>> +			if (err)
>> +				break;
>> +			__br_mdb_notify(dev, p, entry, RTM_DELMDB);
>>   		}
>>   	} else {
>>   		err = __br_mdb_del(br, entry);
>> 
>
> This can potentially break user-space scripts that rely on the best-effort
> behaviour, this is the normal "delete without vid & enabled vlan filtering".
> You can check the fdb delete code which does the same, this was intentional.
>
> You can add an mdb entry without a vid to all vlans, add a vlan and then try
> to remove it from all vlans where it is present - with this patch obviously
> that will fail at the new vlan.

OK good to know. That intention wasn't obvious. I can make __br_mdb_del
return void instead? What about the rest of the patchset if I do so?

Thanks,

        Vivien