From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-24.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88BCCC433EF for ; Thu, 16 Sep 2021 17:26:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 641546128B for ; Thu, 16 Sep 2021 17:26:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348234AbhIPR1n (ORCPT ); Thu, 16 Sep 2021 13:27:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:51940 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244138AbhIPQ4u (ORCPT ); Thu, 16 Sep 2021 12:56:50 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id BDD5761ABE; Thu, 16 Sep 2021 16:31:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1631809875; bh=NyYDkBj2exwUxrdJ3yy0kdAm2cAfu+ZrmkTsZjwhJdw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OQVr09+qvvOQ08bvnUVF9mE8LiQVwqrKA0unZ94nZ8Ct4N9b6IeXMyLJo8ZaFFMGm uogymu1QKijxCOjEvWqM/mLor3CT+rrslUSFz3kb6QNW8p9qMvqVIVcmMNbgcK+dg9 nmz8yHstQ+Wv6CQ1ldYplwAOf7xrtHkay86yEoLY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yonghong Song , Andrii Nakryiko , Sasha Levin Subject: [PATCH 5.13 283/380] selftests/bpf: Fix flaky send_signal test Date: Thu, 16 Sep 2021 18:00:40 +0200 Message-Id: <20210916155813.708143491@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210916155803.966362085@linuxfoundation.org> References: <20210916155803.966362085@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Yonghong Song [ Upstream commit b16ac5bf732a5e23d164cf908ec7742d6a6120d3 ] libbpf CI has reported send_signal test is flaky although I am not able to reproduce it in my local environment. But I am able to reproduce with on-demand libbpf CI ([1]). Through code analysis, the following is possible reason. The failed subtest runs bpf program in softirq environment. Since bpf_send_signal() only sends to a fork of "test_progs" process. If the underlying current task is not "test_progs", bpf_send_signal() will not be triggered and the subtest will fail. To reduce the chances where the underlying process is not the intended one, this patch boosted scheduling priority to -20 (highest allowed by setpriority() call). And I did 10 runs with on-demand libbpf CI with this patch and I didn't observe any failures. [1] https://github.com/libbpf/libbpf/actions/workflows/ondemand.yml Signed-off-by: Yonghong Song Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20210817190923.3186725-1-yhs@fb.com Signed-off-by: Sasha Levin --- .../selftests/bpf/prog_tests/send_signal.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/send_signal.c b/tools/testing/selftests/bpf/prog_tests/send_signal.c index 7043e6ded0e6..75b72c751772 100644 --- a/tools/testing/selftests/bpf/prog_tests/send_signal.c +++ b/tools/testing/selftests/bpf/prog_tests/send_signal.c @@ -1,5 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 #include +#include +#include #include "test_send_signal_kern.skel.h" static volatile int sigusr1_received = 0; @@ -41,12 +43,23 @@ static void test_send_signal_common(struct perf_event_attr *attr, } if (pid == 0) { + int old_prio; + /* install signal handler and notify parent */ signal(SIGUSR1, sigusr1_handler); close(pipe_c2p[0]); /* close read */ close(pipe_p2c[1]); /* close write */ + /* boost with a high priority so we got a higher chance + * that if an interrupt happens, the underlying task + * is this process. + */ + errno = 0; + old_prio = getpriority(PRIO_PROCESS, 0); + ASSERT_OK(errno, "getpriority"); + ASSERT_OK(setpriority(PRIO_PROCESS, 0, -20), "setpriority"); + /* notify parent signal handler is installed */ CHECK(write(pipe_c2p[1], buf, 1) != 1, "pipe_write", "err %d\n", -errno); @@ -62,6 +75,9 @@ static void test_send_signal_common(struct perf_event_attr *attr, /* wait for parent notification and exit */ CHECK(read(pipe_p2c[0], buf, 1) != 1, "pipe_read", "err %d\n", -errno); + /* restore the old priority */ + ASSERT_OK(setpriority(PRIO_PROCESS, 0, old_prio), "setpriority"); + close(pipe_c2p[1]); close(pipe_p2c[0]); exit(0); -- 2.30.2