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Subject: Re: [RFC v2 00/23] io_uring BPF requests
To:     Song Liu <songliubraving@fb.com>
Cc:     "io-uring@vger.kernel.org" <io-uring@vger.kernel.org>,
        Networking <netdev@vger.kernel.org>,
        "bpf@vger.kernel.org" <bpf@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Jens Axboe <axboe@kernel.dk>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>, Martin Lau <kafai@fb.com>,
        Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Horst Schirmeier <horst.schirmeier@tu-dortmund.de>,
        "Franz-B . Tuneke" <franz-bernhard.tuneke@tu-dortmund.de>,
        Christian Dietrich <stettberger@dokucode.de>
References: <cover.1621424513.git.asml.silence@gmail.com>
 <0A3E3601-76CC-4196-8246-CCAEB8C8AED3@fb.com>
From:   Pavel Begunkov <asml.silence@gmail.com>
Message-ID: <a83f147b-ea9d-e693-a2e9-c6ce16659749@gmail.com>
Date:   Fri, 21 May 2021 01:58:59 +0100
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On 5/21/21 1:35 AM, Song Liu wrote:
>> On May 19, 2021, at 7:13 AM, Pavel Begunkov <asml.silence@gmail.com> wrote:
>> The main problem solved is feeding completion information of other
>> requests in a form of CQEs back into BPF. I decided to wire up support
>> for multiple completion queues (aka CQs) and give BPF programs access to
>> them, so leaving userspace in control over synchronisation that should
>> be much more flexible that the link-based approach.
>>
>> For instance, there can be a separate CQ for each BPF program, so no
>> extra sync is needed, and communication can be done by submitting a
>> request targeting a neighboring CQ or submitting a CQE there directly
>> (see test3 below). CQ is choosen by sqe->cq_idx, so everyone can
>> cross-fire if willing.
>>
> 
> [...]
> 
>>  bpf: add IOURING program type
>>  io_uring: implement bpf prog registration
>>  io_uring: add support for bpf requests
>>  io_uring: enable BPF to submit SQEs
>>  io_uring: enable bpf to submit CQEs
>>  io_uring: enable bpf to reap CQEs
>>  libbpf: support io_uring
>>  io_uring: pass user_data to bpf executor
>>  bpf: Add bpf_copy_to_user() helper
>>  io_uring: wire bpf copy to user
>>  io_uring: don't wait on CQ exclusively
>>  io_uring: enable bpf reqs to wait for CQs
> 
> Besides the a few comments, these BPF related patches look sane to me. 
> Please consider add some selftests (tools/testing/selftests/bpf). 

The comments are noted. Thanks Song

-- 
Pavel Begunkov