From: "Toke Høiland-Jørgensen" <toke@redhat•com>
To: David Ahern <dahern@digitalocean•com>,
Jesper Dangaard Brouer <brouer@redhat•com>,
David Ahern <dsahern@kernel•org>
Cc: netdev@vger•kernel.org, davem@davemloft•net, kuba@kernel•org,
prashantbhole.linux@gmail•com, jasowang@redhat•com,
mst@redhat•com, toshiaki.makita1@gmail•com, daniel@iogearbox•net,
john.fastabend@gmail•com, ast@kernel•org, kafai@fb•com,
songliubraving@fb•com, yhs@fb•com, andriin@fb•com,
dsahern@gmail•com
Subject: Re: [PATCH RFC v4 bpf-next 03/11] xdp: Add xdp_txq_info to xdp_buff
Date: Fri, 28 Feb 2020 11:10:30 +0100 [thread overview]
Message-ID: <87lfonuind.fsf@toke.dk> (raw)
In-Reply-To: <3b57af56-e1c1-acc7-6392-db95337bf564@digitalocean.com>
David Ahern <dahern@digitalocean•com> writes:
> On 2/27/20 4:58 AM, Toke Høiland-Jørgensen wrote:
>> also, an egress program may want to actually know which
>> ingress iface the packet was first received on. So why not just keep
>> both fields? Since ifindex 0 is invalid anyway, the field could just be
>> 0 when it isn't known (e.g., egress ifindex on RX, or ingress ifindex if
>> it comes from the stack)?
>
> Today, the ingress device is lost in the conversion from xdp_buff to
> xdp_frame. The plumbing needed to keep that information is beyond the
> scope of this set.
>
> I am open to making the UAPI separate entries if there is a real reason
> for it. Do you have a specific use case?
I was thinking it could be a nice shorthand for whether a packet comes
from the local stack or was forwarded (0 == stack). But no, I don't have
a concrete application where this is useful. However, if we define it as
a union we lose the ability to change our mind. Together with the
debugability issue I just replied with to your other email, I think it
would be better to expend the four bytes keep them as separate fields,
but still restrict access to the RX ifindex for now.
-Toke
next prev parent reply other threads:[~2020-02-28 10:10 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-27 3:20 [PATCH RFC v4 bpf-next 00/11] Add support for XDP in egress path David Ahern
2020-02-27 3:20 ` [PATCH RFC v4 bpf-next 01/11] net: Add XDP setup and query commands for Tx programs David Ahern
2020-02-27 3:20 ` [PATCH RFC v4 bpf-next 02/11] net: Add BPF_XDP_EGRESS as a bpf_attach_type David Ahern
2020-02-27 3:20 ` [PATCH RFC v4 bpf-next 03/11] xdp: Add xdp_txq_info to xdp_buff David Ahern
2020-02-27 8:00 ` Jesper Dangaard Brouer
2020-02-27 11:58 ` Toke Høiland-Jørgensen
2020-02-28 3:01 ` David Ahern
2020-02-28 10:10 ` Toke Høiland-Jørgensen [this message]
2020-02-27 20:44 ` David Ahern
2020-02-28 10:07 ` Toke Høiland-Jørgensen
2020-02-28 10:41 ` Jesper Dangaard Brouer
2020-02-27 3:20 ` [PATCH RFC v4 bpf-next 04/11] net: Add IFLA_XDP_EGRESS for XDP programs in the egress path David Ahern
2020-02-27 3:20 ` [PATCH RFC v4 bpf-next 05/11] net: core: rename netif_receive_generic_xdp to do_generic_xdp_core David Ahern
2020-02-27 3:20 ` [PATCH RFC v4 bpf-next 06/11] net: core: Rename do_xdp_generic to do_xdp_generic_rx and export David Ahern
2020-02-27 3:20 ` [PATCH RFC v4 bpf-next 07/11] tun: set egress XDP program David Ahern
2020-03-02 3:32 ` Jason Wang
2020-03-02 3:52 ` David Ahern
2020-03-10 2:18 ` David Ahern
2020-02-27 3:20 ` [PATCH RFC v4 bpf-next 08/11] tun: Support xdp in the Tx path for skb David Ahern
2020-03-02 3:28 ` Jason Wang
2020-03-02 3:41 ` David Ahern
2020-03-03 10:46 ` Jesper Dangaard Brouer
2020-03-03 15:36 ` David Ahern
2020-02-27 3:20 ` [PATCH RFC v4 bpf-next 09/11] tun: Support xdp in the Tx path for xdp_frames David Ahern
2020-03-02 18:30 ` Alexei Starovoitov
2020-03-03 4:27 ` David Ahern
2020-03-03 9:08 ` Jesper Dangaard Brouer
2020-03-03 18:16 ` Alexei Starovoitov
2020-03-03 10:40 ` Jesper Dangaard Brouer
2020-03-10 3:06 ` David Ahern
2020-03-10 3:44 ` David Ahern
2020-03-10 9:03 ` Jesper Dangaard Brouer
2020-02-27 3:20 ` [PATCH RFC v4 bpf-next 10/11] libbpf: Add egress XDP support David Ahern
2020-02-27 3:20 ` [PATCH RFC v4 bpf-next 11/11] samples/bpf: xdp1, add " David Ahern
2020-02-27 11:55 ` [PATCH RFC v4 bpf-next 00/11] Add support for XDP in egress path Toke Høiland-Jørgensen
2020-02-27 16:22 ` Alexei Starovoitov
2020-02-27 17:06 ` Toke Høiland-Jørgensen
2020-02-27 18:37 ` Alexei Starovoitov
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