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Date:   Tue, 30 Aug 2022 16:19:16 +0200
From:   netdev@kapio-technology.com
To:     Ido Schimmel <idosch@nvidia.com>
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Subject: Re: [PATCH v5 net-next 1/6] net: bridge: add locked entry fdb flag to
 extend locked port feature
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On 2022-08-29 18:12, Ido Schimmel wrote:
> On Mon, Aug 29, 2022 at 04:02:46PM +0200, netdev@kapio-technology.com 
> wrote:
>> On 2022-08-27 13:30, Nikolay Aleksandrov wrote:
>> > On 26/08/2022 14:45, Hans Schultz wrote:
>> >
>> > Hi,
>> > Please add the blackhole flag in a separate patch.
>> > A few more comments and questions below..
>> >
>> 
>> Hi,
>> if userspace is to set this flag I think I need to change stuff in
>> rtnetlink.c, as I will need to extent struct ndmsg with a new u32 
>> entry as
>> the old u8 flags is full.
> 
> You cannot extend 'struct ndmsg'. That's why 'NDA_FLAGS_EXT' was
> introduced. See:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2c611ad97a82b51221bb0920cc6cac0b1d4c0e52
> 
> 'NTF_EXT_BLACKHOLE' belongs in 'NDA_FLAGS_EXT' like you have it now, 
> but
> the kernel should not reject it in br_fdb_add().
> 
>> Maybe this is straight forward, but I am not so sure as I don't know 
>> that
>> code too well. Maybe someone can give me a hint...?

The question I have is if I can use nlh_flags to send the extended flags 
further on to fdb_add_entry(), where I expect to need it?
(the extended flags are u32, while nlh_flags are u16)