Re: [PATCH v5 net-next 1/6] net: bridge: add locked entry fdb flag to extend locked port feature

Ido Schimmel
2022-09-03T14:27:42Z

On Tue, Aug 30, 2022 at 04:19:16PM +0200, netdev@kapio-technology.com wrote:
> 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?

A separate argument looks cleaner to me.

> (the extended flags are u32, while nlh_flags are u16)