From patchwork Fri Feb 14 17:02:11 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roman Penyaev X-Patchwork-Id: 11382653 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 316D6109A for ; Fri, 14 Feb 2020 17:02:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 19F8B20656 for ; Fri, 14 Feb 2020 17:02:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392649AbgBNRCv (ORCPT ); Fri, 14 Feb 2020 12:02:51 -0500 Received: from mx2.suse.de ([195.135.220.15]:34684 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2394040AbgBNRCt (ORCPT ); Fri, 14 Feb 2020 12:02:49 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 18392B15A; Fri, 14 Feb 2020 17:02:48 +0000 (UTC) From: Roman Penyaev Cc: Roman Penyaev , Max Neunhoeffer , Jakub Kicinski , Christopher Kohlhoff , Davidlohr Bueso , Jason Baron , Andrew Morton , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 2/2] kselftest: introduce new epoll test case Date: Fri, 14 Feb 2020 18:02:11 +0100 Message-Id: <20200214170211.561524-2-rpenyaev@suse.de> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200214170211.561524-1-rpenyaev@suse.de> References: <20200214170211.561524-1-rpenyaev@suse.de> MIME-Version: 1.0 To: unlisted-recipients:; (no To-header on input) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org This testcase repeats epollbug.c from the bug: https://bugzilla.kernel.org/show_bug.cgi?id=205933 What it tests? It tests the race between epoll_ctl() and epoll_wait(). New event mask passed to epoll_ctl() triggers wake up, which can be missed because of the bug described in the link. Reproduction is 100%, so easy to fix. Kudos, Max, for wonderful test case. Signed-off-by: Roman Penyaev Cc: Max Neunhoeffer Cc: Jakub Kicinski Cc: Christopher Kohlhoff Cc: Davidlohr Bueso Cc: Jason Baron Cc: Andrew Morton Cc: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- Nothing was changed in v3 Nothing interesting in v2: changed the comment a bit .../filesystems/epoll/epoll_wakeup_test.c | 67 ++++++++++++++++++- 1 file changed, 66 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c b/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c index 37a04dab56f0..11eee0b60040 100644 --- a/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c +++ b/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c @@ -7,13 +7,14 @@ #include #include #include +#include #include "../../kselftest_harness.h" struct epoll_mtcontext { int efd[3]; int sfd[4]; - int count; + volatile int count; pthread_t main; pthread_t waiter; @@ -3071,4 +3072,68 @@ TEST(epoll58) close(ctx.sfd[3]); } +static void *epoll59_thread(void *ctx_) +{ + struct epoll_mtcontext *ctx = ctx_; + struct epoll_event e; + int i; + + for (i = 0; i < 100000; i++) { + while (ctx->count == 0) + ; + + e.events = EPOLLIN | EPOLLERR | EPOLLET; + epoll_ctl(ctx->efd[0], EPOLL_CTL_MOD, ctx->sfd[0], &e); + ctx->count = 0; + } + + return NULL; +} + +/* + * t0 + * (p) \ + * e0 + * (et) / + * e0 + * + * Based on https://bugzilla.kernel.org/show_bug.cgi?id=205933 + */ +TEST(epoll59) +{ + pthread_t emitter; + struct pollfd pfd; + struct epoll_event e; + struct epoll_mtcontext ctx = { 0 }; + int i, ret; + + signal(SIGUSR1, signal_handler); + + ctx.efd[0] = epoll_create1(0); + ASSERT_GE(ctx.efd[0], 0); + + ctx.sfd[0] = eventfd(1, 0); + ASSERT_GE(ctx.sfd[0], 0); + + e.events = EPOLLIN | EPOLLERR | EPOLLET; + ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0); + + ASSERT_EQ(pthread_create(&emitter, NULL, epoll59_thread, &ctx), 0); + + for (i = 0; i < 100000; i++) { + ret = epoll_wait(ctx.efd[0], &e, 1, 1000); + ASSERT_GT(ret, 0); + + while (ctx.count != 0) + ; + ctx.count = 1; + } + if (pthread_tryjoin_np(emitter, NULL) < 0) { + pthread_kill(emitter, SIGUSR1); + pthread_join(emitter, NULL); + } + close(ctx.efd[0]); + close(ctx.sfd[0]); +} + TEST_HARNESS_MAIN