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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nJZJsNV7; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nJZJsNV7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BF4EDC4CEC4; Fri, 6 Sep 2024 09:45:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1725615932; bh=LernRSShNGa1mGc7qRZaNzj+Q6K/W+vBl6auj/fdMM8=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=nJZJsNV7QTdSVinjVvM1g4G5m8Pk3jBcq23jzm1xwmU8gB4ogNYV+wgfk96/f9GXS DMnXqKYHFT6asJFw1GpRc/W/QhQcIGMHK7QPY8RI4od0CowpqOv++A7nL5A2YhPTXx LciT6GKTPYwmacQpeNVlHbQvIRQ+dtLurazXYPuOOaJOKXU5Vuts7Ek7DA0soxtLnC LYleEnplrg8A6KsXMLpbsXn3UVUkYOaeL3BaoIOVLj2XuM8lE5BeBHirKc+PcXCXvy 3ASbcv2hB795TT3gzqk7Gb6zG7XC5VuOqUcXrdrKKlW+M01HaIjnxXv0f+BSJurBC0 oJcTGvfaWoxbw== Message-ID: <61dcb4af29b8922b442429607767332640cdf223.camel@kernel.org> Subject: Re: [PATCH mptcp-next] Squash to "selftests/bpf: Add getsockopt to inspect mptcp subflow" From: Geliang Tang To: Matthieu Baerts , mptcp@lists.linux.dev Cc: Geliang Tang Date: Fri, 06 Sep 2024 17:45:27 +0800 In-Reply-To: References: <11a224e1bade27689271af77cd47c6a49852a2cf.1725543947.git.tanggeliang@kylinos.cn> Autocrypt: addr=geliang@kernel.org; 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charset="UTF-8" User-Agent: Evolution 3.52.3-0ubuntu1 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Matt, On Thu, 2024-09-05 at 16:03 +0200, Matthieu Baerts wrote: > Hi Geliang, > > On 05/09/2024 15:46, Geliang Tang wrote: > > From: Geliang Tang > > > > Update error messages: > > > >  run_subflow:FAIL:mark unexpected mark: actual 3 != expected 0 > >  run_subflow:FAIL:cc unexpected cc: actual 'reno' != expected > > 'cubic' > > That's a good idea to improve the error message in case of error, but > I > think this technique or changing the optval is dangerous: > > (...) > > > diff --git a/tools/testing/selftests/bpf/progs/mptcp_subflow.c > > b/tools/testing/selftests/bpf/progs/mptcp_subflow.c > > index 70302477e326..a5e42bfddbbf 100644 > > --- a/tools/testing/selftests/bpf/progs/mptcp_subflow.c > > +++ b/tools/testing/selftests/bpf/progs/mptcp_subflow.c > > @@ -63,6 +63,7 @@ int mptcp_subflow(struct bpf_sock_ops *skops) > >  static int _check_getsockopt_subflow_mark(struct mptcp_sock *msk, > > struct bpf_sockopt *ctx) > >  { > >   struct mptcp_subflow_context *subflow; > > + int *optval = ctx->optval; > >   int i = 0; > >   > >   mptcp_for_each_subflow(msk, subflow) { > > @@ -72,7 +73,10 @@ static int _check_getsockopt_subflow_mark(struct > > mptcp_sock *msk, struct bpf_soc > >      struct > > mptcp_subflow_context)); > >   > >   if (ssk->sk_mark != ++i) { > > - ctx->retval = -2; > > + if (ctx->optval + sizeof(int) <= ctx- > > >optval_end) { > > + *optval = ssk->sk_mark; > > I guess a likely error to have is that the mark (or the cc) has not > been > changed on the subflow, and it then has its default value. In this > case > here with the mark, you will not change optval: it will be 0 before, > and > you will set it to 0. That means your test will not fail here (retval > = > 0) or in the verifications done by the userspace (mark = 0). > > I think it is safer not to change 'optval' here in the verification > step. If you want to pass info to the userspace, can you not write a > string somewhere? e.g. skel->bss->error_msg, or using a storage map? Let's drop this patch then. Please send v5 of "new MPTCP subflow subtest" set to bpf-next for me. Thanks, -Geliang > > Cheers, > Matt