linux-kernel - Re: [RFC nf-next v5 0/2] netfilter: bpf: support prog update

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Date: Wed, 14 Feb 2024 17:41:17 +0100
From: Pablo Neira Ayuso <pablo@...filter.org>
To: Quentin Deslandes <qde@...cy.de>
Cc: "D. Wythe" <alibuda@...ux.alibaba.com>, kadlec@...filter.org,
	fw@...len.de, bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org, coreteam@...filter.org,
	netfilter-devel@...r.kernel.org, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	ast@...nel.org
Subject: Re: [RFC nf-next v5 0/2] netfilter: bpf: support prog update

On Wed, Feb 14, 2024 at 05:10:46PM +0100, Quentin Deslandes wrote:
> On 2024-01-02 07:11, D. Wythe wrote:
> > From: "D. Wythe" <alibuda@...ux.alibaba.com>
> > 
> > This patches attempt to implements updating of progs within
> > bpf netfilter link, allowing user update their ebpf netfilter
> > prog in hot update manner.
> > 
> > Besides, a corresponding test case has been added to verify
> > whether the update works.
> > --
> > v1:
> > 1. remove unnecessary context, access the prog directly via rcu.
> > 2. remove synchronize_rcu(), dealloc the nf_link via kfree_rcu.
> > 3. check the dead flag during the update.
> > --
> > v1->v2:
> > 1. remove unnecessary nf_prog, accessing nf_link->link.prog in direct.
> > --
> > v2->v3:
> > 1. access nf_link->link.prog via rcu_dereference_raw to avoid warning.
> > --
> > v3->v4:
> > 1. remove mutex for link update, as it is unnecessary and can be replaced
> > by atomic operations.
> > --
> > v4->v5:
> > 1. fix error retval check on cmpxhcg
> > 
> > D. Wythe (2):
> >   netfilter: bpf: support prog update
> >   selftests/bpf: Add netfilter link prog update test
> > 
> >  net/netfilter/nf_bpf_link.c                        | 50 ++++++++-----
> >  .../bpf/prog_tests/netfilter_link_update_prog.c    | 83 ++++++++++++++++++++++
> >  .../bpf/progs/test_netfilter_link_update_prog.c    | 24 +++++++
> >  3 files changed, 141 insertions(+), 16 deletions(-)
> >  create mode 100644 tools/testing/selftests/bpf/prog_tests/netfilter_link_update_prog.c
> >  create mode 100644 tools/testing/selftests/bpf/progs/test_netfilter_link_update_prog.c
> > 
> 
> It seems this patch has been forgotten, hopefully this answer
> will give it more visibility.
> 
> I've applied this change on 6.8.0-rc4 and tested BPF_LINK_UPDATE
> with bpfilter and everything seems alright.

Just post it without RFC tag.