Re: [PATCH bpf-next/net v2 7/7] selftests/bpf: Add mptcp_subflow bpf_iter subtest

On 12/19/24 7:46 AM, Matthieu Baerts (NGI0) wrote:

+SEC("cgroup/getsockopt") +int iters_subflow(struct bpf_sockopt *ctx) +{

• struct mptcp_subflow_context *subflow;
• struct bpf_sock *sk = ctx->sk;
• struct sock *ssk = NULL;
• struct mptcp_sock *msk;
• int local_ids = 0;
• if (ctx->level != SOL_TCP || ctx->optname != TCP_IS_MPTCP)

• return 1;
  

• msk = bpf_skc_to_mptcp_sock(sk);
• if (!msk || msk->pm.server_side || !msk->pm.subflows)

• return 1;
  

• msk = bpf_mptcp_sock_acquire(msk);
• if (!msk)

• return 1;
  

• bpf_for_each(mptcp_subflow, subflow, msk) {

• /* Here MPTCP-specific packet scheduler kfunc can be called:
  

•  * this test is not doing anything really useful, only to
  

•  * verify the iteration works.
  

•  */
  

• local_ids += subflow->subflow_id;
  

• /* only to check the following kfunc works */
  

• ssk = mptcp_subflow_tcp_sock(subflow);
  

It is good to have test cases to exercise the new iter and kfunc. Thanks.

However, it seems not useful to show how it will be used in the future packet/subflow scheduler. iiuc, the core piece is in bpf_struct_ops. Without it, it is hard to comment. Any RFC patches ready to be posted?

• }
• if (!ssk)

• goto out;
  

• /* assert: if not OK, something wrong on the kernel side */
• if (ssk->sk_dport != ((struct sock *)msk)->sk_dport)

• goto out;
  

• /* only to check the following kfunc works */
• subflow = bpf_mptcp_subflow_ctx(ssk);
• if (!subflow || subflow->token != msk->token)

• goto out;
  

• ids = local_ids;

+out:

• bpf_mptcp_sock_release(msk);
• return 1;

+}