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

[Yonghong Song <yhs@fb.com>]

On 6/25/21 1:04 PM, Martin KaFai Lau wrote:
> This set is to allow bpf tcp iter to call bpf_setsockopt.
> 
> 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 with the netadmin cap to call
> bpf_setsockopt(TCP_CONGESTION).  It is not limited to TCP_CONGESTION
> and the bpf tcp iter can call bpf_setsockopt() 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_setsockopt.
> 
> 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_setsockopt in bpf tcp iter
>    bpf: selftest: Test batching and bpf_setsockopt in bpf tcp iter
> 
>   include/linux/bpf.h                           |   7 +
>   include/net/inet_hashtables.h                 |   6 +
>   include/net/tcp.h                             |   1 -
>   kernel/bpf/bpf_iter.c                         |  22 +
>   kernel/trace/bpf_trace.c                      |   7 +-
>   net/core/filter.c                             |  17 +
>   net/ipv4/tcp_ipv4.c                           | 409 ++++++++++++++----
>   tools/testing/selftests/bpf/network_helpers.c |  85 +++-
>   tools/testing/selftests/bpf/network_helpers.h |   4 +
>   .../bpf/prog_tests/bpf_iter_setsockopt.c      | 226 ++++++++++
>   .../selftests/bpf/progs/bpf_iter_setsockopt.c |  76 ++++
>   .../selftests/bpf/progs/bpf_tracing_net.h     |   4 +
>   12 files changed, 767 insertions(+), 97 deletions(-)
>   create mode 100644 tools/testing/selftests/bpf/prog_tests/bpf_iter_setsockopt.c
>   create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_setsockopt.c

I have a few minor comments (replying to individual commits). But 
overall LGTM.

Acked-by: Yonghong Song <yhs@fb.com>