Re: [PATCH mptcp-next v9 0/7] add mptcp_subflow bpf_iter

[Geliang Tang <geliang@kernel.org>]

Hi Matt,

Thanks for this review.

On Mon, 2024-10-14 at 18:08 +0200, Matthieu Baerts wrote:
> Hi Geliang,
> 
> On 09/10/2024 12:05, MPTCP CI wrote:
> > Hi Geliang,
> > 
> > Thank you for your modifications, that's great!
> > 
> > But sadly, our CI spotted some issues with it when trying to build
> > it.
> > 
> > You can find more details there:
> > 
> >  
> > https://github.com/multipath-tcp/mptcp_net-next/actions/runs/11252652867
> 
> I was looking at applying this series, but there are some issues
> reported by the CI:
> 
>   warning: symbol 'bpf_*mptcp_*' was not declared. Should it be
> static?
> 
> Could it be possible to have a fix for that please before applying
> the
> series?

No fix is ​​needed, just ignore these warnings. This error is also
reported in other places:

$ make C=1 -o net/socket.o
  CALL    scripts/checksyscalls.sh
  DESCEND objtool
  INSTALL libsubcmd_headers
  DESCEND bpf/resolve_btfids
  INSTALL libsubcmd_headers
  CC      net/socket.o
  CHECK   net/socket.c
net/socket.c:1704:21: warning: symbol 'update_socket_protocol' was not
declared. Should it be static?

It seems that it is because "-Wmissing-declarations" is not recognized
by sparse

> 
> I guess you are missing __bpf_kfunc_start_defs() and
> __bpf_kfunc_end_defs() around the declaration of the BPF dedicated
> kfunc, no?

No. __bpf_kfunc_start_defs() and __bpf_kfunc_end_defs() are indeed used
in patch 2. 

> 
> 
> Also, where should I apply these patches? Before "mptcp: add
> sched_data
> helpers"?

Yes, before "mptcp: add sched_data helpers", after "selftests/bpf: Add
mptcp subflow subtest".

> But then there should not be any dependences on the BPF
> scheduler work (and I think that would be better without this
> dependence, see my comment on patch 4/7)

This set doesn't have any dependence on the BPF packet scheduler since
the selftest is added as a ftrace. It somehow depends on packet
scheduler since it invoke some packet scheduler functions such as
mptcp_subflow_active() and bpf_mptcp_subflow_tcp_sock().

> 
> Cheers,
> Matt