Re: [PATCH mptcp-next v5 1/5] bpf: Add mptcp_subflow bpf_iter

[Martin KaFai Lau <martin.lau@xxxxxxxxx>]

On 9/13/24 1:57 PM, Andrii Nakryiko wrote:
> > > > +__bpf_kfunc int bpf_iter_mptcp_subflow_new(struct
> > > > bpf_iter_mptcp_subflow *it,
> > > > +                                          struct mptcp_sock *msk)
> > > > +{
> > > > +       struct bpf_iter_mptcp_subflow_kern *kit = (void *)it;
> > > > +
> > > > +       kit->msk = msk;
> > > > +       if (!msk)
> > > > +               return -EINVAL;
> > > > +
> > > > +       kit->pos = &msk->conn_list;
> > > > +       return 0;
> > > > +}

[ ... ]

> > > >   BTF_KFUNCS_START(bpf_mptcp_sched_kfunc_ids)
> > > > +BTF_ID_FLAGS(func, bpf_iter_mptcp_subflow_new)
> > >
> > > I'm not 100% sure, but I suspect you might need to specify
> > > KF_TRUSTED_ARGS here to ensure that `struct mptcp_sock *msk` is a

+1

> > > > @@ -241,6 +286,8 @@ static int __init bpf_mptcp_kfunc_init(void)
> > > >          int ret;
> > > >
> > > >          ret = register_btf_fmodret_id_set(&bpf_mptcp_fmodret_set);
> > > > +       ret = ret ?:
> > > > register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING,
> > > > +
> > > > &bpf_mptcp_sched_kfunc_set);

This cannot be used in tracing.

Going back to my earlier question in v1. How is the msk->conn_list protected?