linux-kernel - Re: [PATCH bpf-next v5 0/6] Support direct writes to nf

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Date:   Sat, 10 Sep 2022 02:27:38 +0200
From:   Kumar Kartikeya Dwivedi <memxor@...il.com>
To:     Daniel Xu <dxu@...uu.xyz>
Cc:     bpf@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
        andrii@...nel.org, pablo@...filter.org, fw@...len.de,
        toke@...nel.org, martin.lau@...ux.dev,
        netfilter-devel@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next v5 0/6] Support direct writes to nf_conn:mark

On Wed, 7 Sept 2022 at 18:41, Daniel Xu <dxu@...uu.xyz> wrote:
>
> Support direct writes to nf_conn:mark from TC and XDP prog types. This
> is useful when applications want to store per-connection metadata. This
> is also particularly useful for applications that run both bpf and
> iptables/nftables because the latter can trivially access this metadata.
>
> One example use case would be if a bpf prog is responsible for advanced
> packet classification and iptables/nftables is later used for routing
> due to pre-existing/legacy code.
>

There are a couple of compile time warnings when conntrack is disabled,

../net/core/filter.c:8608:1: warning: symbol 'nf_conn_btf_access_lock'
was not declared. Should it be static?
../net/core/filter.c:8611:5: warning: symbol 'nfct_bsa' was not
declared. Should it be static?

Most likely because extern declaration is guarded by ifdefs. So just
moving those out of ifdef should work.
I guess you can send that as a follow up fix, or roll it in if you end
up respinning.

Otherwise, for the series:
Acked-by: Kumar Kartikeya Dwivedi <memxor@...il.com>