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

[Martin KaFai Lau <martin.lau@linux.dev>]

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?