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From: "Björn Töpel" <bjorn.topel@gmail.com>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: Netdev <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Alexei Starovoitov <ast@kernel.org>,
	David Miller <davem@davemloft.net>,
	Jesper Dangaard Brouer <brouer@redhat.com>,
	John Fastabend <john.fastabend@gmail.com>
Subject: Re: [PATCH bpf-next 2/2] xdp: Use bulking for non-map XDP_REDIRECT
Date: Fri, 10 Jan 2020 16:54:30 +0100	[thread overview]
Message-ID: <CAJ+HfNhO9Mn-hzysEfri3hAH29HXiBWDZE1XUVhOj1UFbBrp4w@mail.gmail.com> (raw)
In-Reply-To: <87d0brxr9u.fsf@toke.dk>

On Fri, 10 Jan 2020 at 16:30, Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> Björn Töpel <bjorn.topel@gmail.com> writes:
>
[...]
> >
> > After these changes, does the noinline (commit 47b123ed9e99 ("xdp:
> > split code for map vs non-map redirect")) still make sense?
>
> Hmm, good question. The two code paths are certainly close to one
> another; and I guess they could be consolidated further.
>
> The best case would be if we had a way to lookup the ifindex directly in
> the helper. Do you know if there's a way to get the current net
> namespace from the helper? Can we use current->nsproxy->net_ns in that
> context?
>

Nope, interrupt context. :-( Another (ugly) way is adding a netns
member to the bpf_redirect_info, that is populated by the driver
(driver changes everywhere -- ick). So no.

(And *if* one would go the route of changing all drivers, I think the
percpu bpf_redirect_info should be replaced a by a context that is
passed from the driver to the XDP program execution and
xdp_do_redirect/flush. But that's a much bigger patch. :-))


Björn


> If we can, and if we don't mind merging the two different tracepoints,
> the xdp_do_redirect() function could be made quite a bit leaner...
>
> -Toke
>

  reply	other threads:[~2020-01-10 15:54 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-10 14:22 [PATCH bpf-next 0/2] xdp: Introduce " Toke Høiland-Jørgensen
2020-01-10 14:22 ` [PATCH bpf-next 1/2] xdp: Move devmap bulk queue into struct net_device Toke Høiland-Jørgensen
2020-01-10 15:03   ` Björn Töpel
2020-01-10 15:26     ` Toke Høiland-Jørgensen
2020-01-10 16:08   ` Jesper Dangaard Brouer
2020-01-10 22:34     ` Toke Høiland-Jørgensen
2020-01-10 22:46       ` Eric Dumazet
2020-01-10 23:16         ` Toke Høiland-Jørgensen
2020-01-10 14:22 ` [PATCH bpf-next 2/2] xdp: Use bulking for non-map XDP_REDIRECT Toke Høiland-Jørgensen
2020-01-10 15:15   ` Björn Töpel
2020-01-10 15:30     ` Toke Høiland-Jørgensen
2020-01-10 15:54       ` Björn Töpel [this message]
2020-01-10 15:57         ` Toke Høiland-Jørgensen

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