From patchwork Fri Jan 21 07:30:26 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin KaFai Lau X-Patchwork-Id: 12719376 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5F6BCC433F5 for ; Fri, 21 Jan 2022 07:30:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378989AbiAUHaj (ORCPT ); Fri, 21 Jan 2022 02:30:39 -0500 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:48534 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1378984AbiAUHah (ORCPT ); Fri, 21 Jan 2022 02:30:37 -0500 Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.1.2/8.16.1.2) with ESMTP id 20L06frC010885 for ; Thu, 20 Jan 2022 23:30:37 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding : content-type; s=facebook; bh=7GflWt4fi0AeOActFjaj98OUlkg6Vpv4+Ho/5AqMZaM=; b=N/LBThNC8Q8WrZLR/h/liTcbn+ykIA4pRa1xULvBs6HziPQRLDwT+lqPTlzLPS1ZUBhg PQjtY50zSAoMuDRBUsLxLtHLgS3Rge8Ls8k5x1derfQ2D0k6KDc4lhy+Axi0jEiA27/N 44EZXVGreCpprqGgJYxDmyLWtHVfxwL1ei8= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3dqj0ghnbn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Thu, 20 Jan 2022 23:30:36 -0800 Received: from twshared22811.39.frc1.facebook.com (2620:10d:c085:108::4) by mail.thefacebook.com (2620:10d:c085:11d::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Thu, 20 Jan 2022 23:30:36 -0800 Received: by devbig005.ftw2.facebook.com (Postfix, from userid 6611) id 29B025BDEBEE; Thu, 20 Jan 2022 23:30:26 -0800 (PST) From: Martin KaFai Lau To: , CC: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , David Miller , Eric Dumazet , Jakub Kicinski , , Willem de Bruijn Subject: [RFC PATCH v3 net-next 0/4] Preserve mono delivery time (EDT) in skb->tstamp Date: Thu, 20 Jan 2022 23:30:26 -0800 Message-ID: <20220121073026.4173996-1-kafai@fb.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: 4B2-_BzQGTr6ayeDBeeuRmaEkgCj1W14 X-Proofpoint-GUID: 4B2-_BzQGTr6ayeDBeeuRmaEkgCj1W14 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.816,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-01-21_02,2022-01-20_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=fb_outbound_notspam policy=fb_outbound score=0 mlxscore=0 adultscore=0 clxscore=1015 bulkscore=0 impostorscore=0 spamscore=0 phishscore=0 suspectscore=0 mlxlogscore=999 lowpriorityscore=0 malwarescore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2201210047 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org X-Patchwork-State: RFC skb->tstamp was first used as the (rcv) timestamp in real time clock base. The major usage is to report it to the user (e.g. SO_TIMESTAMP). Later, skb->tstamp is also set as the (future) delivery_time (e.g. EDT in TCP) during egress and used by the qdisc (e.g. sch_fq) to make decision on when the skb can be passed to the dev. Currently, there is no way to tell skb->tstamp having the (rcv) timestamp or the delivery_time, so it is always reset to 0 whenever forwarded between egress and ingress. While it makes sense to always clear the (rcv) timestamp in skb->tstamp to avoid confusing sch_fq that expects the delivery_time, it is a performance issue [0] to clear the delivery_time if the skb finally egress to a fq@phy-dev. v3: - Feedback from v2 is using shinfo(skb)->tx_flags could be racy. - Considered to reuse a few bits in skb->tstamp to represent different semantics, other than more code churns, it will break the bpf usecase which currently can write and then read back the skb->tstamp. - Went back to v1 idea on adding a bit to skb and address the feedbacks on v1: - Added one bit skb->mono_delivery_time to flag that the skb->tstamp has the mono delivery_time (EDT), instead of adding a bit to flag if the skb->tstamp has been forwarded or not. - Instead of resetting the delivery_time back to the (rcv) timestamp during recvmsg syscall which may be too late and not useful, the delivery_time reset in v3 happens earlier once the stack knows that the skb will be delivered locally. - Handled the tapping@ingress case by af_packet - No need to change the (rcv) timestamp to mono clock base as in v1. The added one bit to flag skb->mono_delivery_time is enough to keep the EDT delivery_time during forward. - Added logic to the bpf side to make the existing bpf running at ingress can still get the (rcv) timestamp when reading the __sk_buff->tstamp. New __sk_buff->mono_delivery_time is also added. Test is still needed to test this piece. Martin KaFai Lau (4): net: Add skb->mono_delivery_time to distinguish mono delivery_time from (rcv) timestamp net: Add skb_clear_tstamp() to keep the mono delivery_time net: Set skb->mono_delivery_time and clear it when delivering locally bpf: Add __sk_buff->mono_delivery_time and handle __sk_buff->tstamp based on tc_at_ingress drivers/net/loopback.c | 2 +- include/linux/filter.h | 31 ++++- include/linux/skbuff.h | 64 ++++++++-- include/uapi/linux/bpf.h | 1 + net/bridge/br_forward.c | 2 +- net/bridge/netfilter/nf_conntrack_bridge.c | 5 +- net/core/dev.c | 4 +- net/core/filter.c | 140 +++++++++++++++++++-- net/core/skbuff.c | 8 +- net/ipv4/ip_forward.c | 2 +- net/ipv4/ip_input.c | 1 + net/ipv4/ip_output.c | 5 +- net/ipv4/tcp_output.c | 16 +-- net/ipv6/ip6_input.c | 1 + net/ipv6/ip6_output.c | 7 +- net/ipv6/netfilter.c | 5 +- net/netfilter/ipvs/ip_vs_xmit.c | 6 +- net/netfilter/nf_dup_netdev.c | 2 +- net/netfilter/nf_flow_table_ip.c | 4 +- net/netfilter/nft_fwd_netdev.c | 2 +- net/openvswitch/vport.c | 2 +- net/packet/af_packet.c | 4 +- net/sched/act_bpf.c | 5 +- net/sched/cls_bpf.c | 6 +- net/xfrm/xfrm_interface.c | 2 +- tools/include/uapi/linux/bpf.h | 1 + 26 files changed, 265 insertions(+), 63 deletions(-)