netdev - Re: [PATCH v2 bpf-next 0/8] bpf: Allow bpf tcp iter to do bpf

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Date:   Thu, 22 Jul 2021 15:25:39 +0200
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Martin KaFai Lau <kafai@...com>, bpf@...r.kernel.org
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Eric Dumazet <edumazet@...gle.com>, kernel-team@...com,
        Neal Cardwell <ncardwell@...gle.com>, netdev@...r.kernel.org,
        Yonghong Song <yhs@...com>, Yuchung Cheng <ycheng@...gle.com>
Subject: Re: [PATCH v2 bpf-next 0/8] bpf: Allow bpf tcp iter to do
 bpf_(get|set)sockopt



On 7/1/21 10:05 PM, Martin KaFai Lau wrote:
> This set is to allow bpf tcp iter to call bpf_(get|set)sockopt.
> 
> With bpf-tcp-cc, new algo rollout happens more often.  Instead of
> restarting the applications to pick up the new tcp-cc, this set
> allows the bpf tcp iter to call bpf_(get|set)sockopt(TCP_CONGESTION).
> It is not limited to TCP_CONGESTION, the bpf tcp iter can call
> bpf_(get|set)sockopt() with other options.  The bpf tcp iter can read
> into all the fields of a tcp_sock, so there is a lot of flexibility
> to select the desired sk to do setsockopt(), e.g. it can test for
> TCP_LISTEN only and leave the established connections untouched,
> or check the addr/port, or check the current tcp-cc name, ...etc.
> 
> Patch 1-4 are some cleanup and prep work in the tcp and bpf seq_file.
> 
> Patch 5 is to have the tcp seq_file iterate on the
> port+addr lhash2 instead of the port only listening_hash.
> 
> Patch 6 is to have the bpf tcp iter doing batching which
> then allows lock_sock.  lock_sock is needed for setsockopt.
> 
> Patch 7 allows the bpf tcp iter to call bpf_(get|set)sockopt.
> 
> v2:
> - Use __GFP_NOWARN in patch 6
> - Add bpf_getsockopt() in patch 7 to give a symmetrical user experience.
>   selftest in patch 8 is changed to also cover bpf_getsockopt().
> - Remove CAP_NET_ADMIN check in patch 7. Tracing bpf prog has already
>   required CAP_SYS_ADMIN or CAP_PERFMON.
> - Move some def macros to bpf_tracing_net.h in patch 8
> 
> Martin KaFai Lau (8):
>   tcp: seq_file: Avoid skipping sk during tcp_seek_last_pos
>   tcp: seq_file: Refactor net and family matching
>   bpf: tcp: seq_file: Remove bpf_seq_afinfo from tcp_iter_state
>   tcp: seq_file: Add listening_get_first()
>   tcp: seq_file: Replace listening_hash with lhash2
>   bpf: tcp: bpf iter batching and lock_sock
>   bpf: tcp: Support bpf_(get|set)sockopt in bpf tcp iter
>   bpf: selftest: Test batching and bpf_(get|set)sockopt in bpf tcp iter

For the whole series :

Reviewed-by: Eric Dumazet <edumazet@...gle.com>

Sorry for the delay.

BTW, it seems weird for new BPF features to use /proc/net "legacy"
infrastructure and update it.