From patchwork Fri Sep 23 22:44:53 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: 12987260 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 ADF2FC04A95 for ; Fri, 23 Sep 2022 22:45:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232696AbiIWWpg (ORCPT ); Fri, 23 Sep 2022 18:45:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55224 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232653AbiIWWpa (ORCPT ); Fri, 23 Sep 2022 18:45:30 -0400 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 27839106504 for ; Fri, 23 Sep 2022 15:45:00 -0700 (PDT) Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 28NM9Kcn030810 for ; Fri, 23 Sep 2022 15:44:55 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : content-type : content-transfer-encoding : mime-version; s=facebook; bh=lJXt5Ubsu8qeV41sq1GA51M5lBK/C5UaoyBiH0W5OlY=; b=I76bChVcpqaw3ziI+mXPzHLisMGyv5lsBWgTpGYYd77WWj3R3jpcPEJNlt4lfBWmEVZ+ fS5IRNjSOe4tBsODGpQVACmYjaUDxB154wnonB+B+sSCvCOP2+4UD6nbQMWECCyHK1AG QELa15XVnvXvFt6e6nqcu8k/3u0wgVIRo3M= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3jsa90n454-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 23 Sep 2022 15:44:55 -0700 Received: from twshared10425.14.frc2.facebook.com (2620:10d:c085:208::f) by mail.thefacebook.com (2620:10d:c085:21d::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 23 Sep 2022 15:44:54 -0700 Received: by devbig933.frc1.facebook.com (Postfix, from userid 6611) id 1A3C69A40674; Fri, 23 Sep 2022 15:44:53 -0700 (PDT) From: Martin KaFai Lau To: , CC: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , David Miller , Eric Dumazet , Jakub Kicinski , , Paolo Abeni Subject: [PATCH v2 bpf-next 0/5] bpf: Remove recursion check for struct_ops prog Date: Fri, 23 Sep 2022 15:44:53 -0700 Message-ID: <20220923224453.2351753-1-kafai@fb.com> X-Mailer: git-send-email 2.30.2 X-FB-Internal: Safe X-Proofpoint-GUID: h3zmxaWUrf3u-5IrkXdPOwzyXk9pvthQ X-Proofpoint-ORIG-GUID: h3zmxaWUrf3u-5IrkXdPOwzyXk9pvthQ X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.528,FMLib:17.11.122.1 definitions=2022-09-23_10,2022-09-22_02,2022-06-22_01 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net From: Martin KaFai Lau The struct_ops is sharing the tracing-trampoline's enter/exit function which tracks prog->active to avoid recursion. It turns out the struct_ops bpf prog will hit this prog->active and unnecessarily skipped running the struct_ops prog. eg. The '.ssthresh' may run in_task() and then interrupted by softirq that runs the same '.ssthresh'. The kernel does not call the tcp-cc's ops in a recursive way, so this set is to remove the recursion check for struct_ops prog. v2: v1 [0] turned into a long discussion on a few cases and also whether it needs to follow the bpf_run_ctx chain if there is tracing bpf_run_ctx (kprobe/trace/trampoline) running in between. It is a good signal that it is not obvious enough to reason about it and needs a tradeoff for a more straight forward approach. This revision uses one bit out of an existing 1 byte hole in the tcp_sock. It is in Patch 4. [0]: https://lore.kernel.org/bpf/20220922225616.3054840-1-kafai@fb.com/T/#md98d40ac5ec295fdadef476c227a3401b2b6b911 Martin KaFai Lau (5): bpf: Add __bpf_prog_{enter,exit}_struct_ops for struct_ops trampoline bpf: Move the "cdg" tcp-cc check to the common sol_tcp_sockopt() bpf: Refactor bpf_setsockopt(TCP_CONGESTION) handling into another function bpf: tcp: Stop bpf_setsockopt(TCP_CONGESTION) in init ops to recur itself selftests/bpf: Check -EBUSY for the recurred bpf_setsockopt(TCP_CONGESTION) arch/x86/net/bpf_jit_comp.c | 3 + include/linux/bpf.h | 4 ++ include/linux/tcp.h | 6 ++ kernel/bpf/trampoline.c | 23 ++++++ net/core/filter.c | 70 ++++++++++++++----- .../selftests/bpf/prog_tests/bpf_tcp_ca.c | 4 ++ tools/testing/selftests/bpf/progs/bpf_dctcp.c | 25 ++++--- 7 files changed, 111 insertions(+), 24 deletions(-)