netdev - Re: [RFC PATCH bpf-next 0/3] Add a new bpf helper for FDB lookup

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Message-ID: <8eda2f23-f526-bd56-b6ac-0d7ae82444b5@gmail.com>
Date:   Wed, 5 Aug 2020 10:36:58 -0600
From:   David Ahern <dsahern@...il.com>
To:     Yoshiki Komachi <komachi.yoshiki@...il.com>,
        John Fastabend <john.fastabend@...il.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        KP Singh <kpsingh@...omium.org>,
        Roopa Prabhu <roopa@...ulusnetworks.com>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        David Ahern <dsahern@...nel.org>, netdev@...r.kernel.org,
        bridge@...ts.linux-foundation.org, bpf@...r.kernel.org
Subject: Re: [RFC PATCH bpf-next 0/3] Add a new bpf helper for FDB lookup

On 8/5/20 4:26 AM, Yoshiki Komachi wrote:
>>
>> Just to clarify for myself. I expect that with just the helpers here
>> we should only expect static configurations to work, e.g. any learning
>> and/or aging is not likely to work if we do redirects in the XDP path.
> 
> As you described above, learning and aging don’t work at this point. 
> 
> IMO, another helper for learning will be required to fill the requirements.
> I guess that the helper will enable us to use the aging feature as well
> because the aging is the functionality of bridge fdb.

One option is to have a flag that bumps the ageing on successful lookup
and do that in 1 call. You will already have access to the fdb entry.