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

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Date: Tue, 20 Feb 2024 15:19:11 +0800
From: "D. Wythe" <alibuda@...ux.alibaba.com>
To: Quentin Deslandes <qde@...cy.de>, pablo@...filter.org,
 kadlec@...filter.org, fw@...len.de
Cc: 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 2/15/24 12:10 AM, 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.
>
> Thanks,
> Quentin

Thanks for your testing. I will send  out a formal version soon.

Best wishes,
D. Wythe