From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-173.mta0.migadu.com (out-173.mta0.migadu.com [91.218.175.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4E5954414 for ; Tue, 27 Aug 2024 05:22:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724736166; cv=none; b=WEFyaxN8hv9ILQU8TTEv/GROsVvyElZTUl1OZQavHesPp5j75WMmmgeltCiL961hBkiE8/TOGmNA4UXsbZSK2qJcfryErB5V0pZaPQt0oipGMv0UojGbG3/0n6/g8yP2rWwX3c9qEQyfEJUr+fteWl6VXkU3S3uVGp283IjN/Ig= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724736166; c=relaxed/simple; bh=865p1tB1kZyRN7bydAmbt8fwb3qP+z0KAosciCpW7EY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=GgzZtM0GVXO5uwAuibRT1OpMSeMERD1mKNLusfj3MvazFCy/0+7CB4vz2MHWIauhUqB9JJq/+DmNKhNfBHwQm11Bbeagx53q+RWVSjFrR2bBGpb7tmdbs+4g6too3Hjt18mGP1GgeItlkiyv2ucgILAeEpK0Dy8wOcsIkdYBceQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=VNTXtM30; arc=none smtp.client-ip=91.218.175.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="VNTXtM30" Message-ID: <54ce6f90-e86c-4921-b1e0-423fcd655d32@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1724736162; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=quh7O3Lz5jDJSUydWdqAttbbklUHh/h5CagJnR7HKh0=; b=VNTXtM30yTbAtX411fM83bPbumH+T0uj887p886clrCgx16kXqokXbs1Am4mCWV2jRyzI0 7U8Xy+W/77ZEUi2Jv6jCg39oL1pV+IV/Tkor+83bUYvyDFRcmpTaK9lRrEJaroT3Um4EqM 2cAO82UWXzRht96RpkM70emhkngmTNo= Date: Mon, 26 Aug 2024 22:22:32 -0700 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH mptcp-next 2/2] selftests/bpf: Add getsockopt to inspect mptcp subflow To: Geliang Tang , Matthieu Baerts Cc: Geliang Tang , mptcp@lists.linux.dev, Martin KaFai Lau References: <3788544d841aa372a810f2d3dce905612063e872.1724142917.git.tanggeliang@kylinos.cn> <407f6a6a-344e-4f12-9293-e43b9a97f8d4@kernel.org> <23cffc2904df37874f35f106975fccc962d6cb8e.camel@kernel.org> <689e3694-d8f9-4511-8363-6f83a3bb1a1d@kernel.org> <547fdd31-a052-4274-a59e-d7177887dbbe@kernel.org> <010b2338434b7df67ac418ad7063543e91c946b9.camel@kernel.org> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Martin KaFai Lau Content-Language: en-US In-Reply-To: <010b2338434b7df67ac418ad7063543e91c946b9.camel@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 8/26/24 2:24 AM, Geliang Tang wrote: >> I'm not an expert in this, but I guess it means you cannot use >> 'mptcp_subflow_active()', because it can modify the 'subflow' >> structure >> that you got with bpf_core_cast() for a read-only usage. > > A read-only function will get the same error. > > I added a read-only function mptcp_subflow_get_scheduled() for testing: > > bool mptcp_subflow_get_scheduled(struct mptcp_subflow_context *subflow) > { > return subflow->scheduled; > } > > And invoke it from BPF in mptcp_for_each_subflow() loop: > > int BPF_PROG(bpf_first_get_subflow, struct mptcp_sock *msk, > struct mptcp_sched_data *data) > { > struct mptcp_subflow_context *subflow, *tmp; > > mptcp_for_each_subflow(msk, tmp) { > subflow = bpf_core_cast(tmp, struct > mptcp_subflow_context); > mptcp_subflow_get_scheduled(subflow); > } > return 0; > } > > The same "arg#0 is untrusted_ptr_ expected ptr_ or socket" occurs. > > Hope Martin can give us a solution for this issue. I don't know the context for this list walking + modify-by-kfunc usage, so the following could be a grain of salt. It seems like fitting the bpf_iter use case. Take a look at some recent bpf_iter additions, e.g. bpf_iter_{task,css}_next(). Also the bpf_for_each macro usage in selftests. There may be some secondary things that need to consider, e.g. how the walked subflow is protected, rcu, refcnt...etc.