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From: Daniel Borkmann <daniel@iogearbox.net>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: David Ahern <dsahern@kernel.org>,
	netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [PATCH bpf 1/2] bpf_redirect_neigh: Support supplying the nexthop as a helper parameter
Date: Mon, 19 Oct 2020 20:23:35 +0200	[thread overview]
Message-ID: <3785e450-313f-c6f0-2742-716c10b6f8a4@iogearbox.net> (raw)
In-Reply-To: <160312349501.7917.13131363910387009253.stgit@toke.dk>

On 10/19/20 6:04 PM, Toke Høiland-Jørgensen wrote:
> From: Toke Høiland-Jørgensen <toke@redhat.com>
> 
> Based on the discussion in [0], update the bpf_redirect_neigh() helper to
> accept an optional parameter specifying the nexthop information. This makes
> it possible to combine bpf_fib_lookup() and bpf_redirect_neigh() without
> incurring a duplicate FIB lookup - since the FIB lookup helper will return
> the nexthop information even if no neighbour is present, this can simply be
> passed on to bpf_redirect_neigh() if bpf_fib_lookup() returns
> BPF_FIB_LKUP_RET_NO_NEIGH.
> 
> [0] https://lore.kernel.org/bpf/393e17fc-d187-3a8d-2f0d-a627c7c63fca@iogearbox.net/
> 
> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>

Looks good to me, thanks! I'll wait till David gets a chance as well to review.
One thing that would have made sense to me (probably worth a v2) is to keep the
fib lookup flag you had back then, meaning sth like BPF_FIB_SKIP_NEIGH which
would then return a BPF_FIB_LKUP_RET_NO_NEIGH before doing the neigh lookup inside
the bpf_ipv{4,6}_fib_lookup() so that programs can just unconditionally use the
combination of bpf_fib_lookup(skb, [...], BPF_FIB_SKIP_NEIGH) with the
bpf_redirect_neigh([...]) extension in that case and not do this bpf_redirect()
vs bpf_redirect_neigh() dance as you have in the selftest in patch 2/2.

Thanks,
Daniel

  reply	other threads:[~2020-10-19 18:23 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-19 16:04 [PATCH bpf 0/2] bpf: Rework bpf_redirect_neigh() to allow supplying nexthop from caller Toke Høiland-Jørgensen
2020-10-19 16:04 ` [PATCH bpf 1/2] bpf_redirect_neigh: Support supplying the nexthop as a helper parameter Toke Høiland-Jørgensen
2020-10-19 18:23   ` Daniel Borkmann [this message]
2020-10-20  3:12     ` David Ahern
2020-10-20  8:59       ` Daniel Borkmann
2020-10-20 13:45         ` David Ahern
2020-10-19 20:23   ` kernel test robot
2020-10-20  3:08   ` David Ahern
2020-10-19 16:04 ` [PATCH bpf 2/2] selftests: Update test_tc_redirect.sh to use the modified bpf_redirect_neigh() Toke Høiland-Jørgensen

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