From patchwork Mon Apr 29 19:19:06 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= X-Patchwork-Id: 13647575 Received: from smtp-1908.mail.infomaniak.ch (smtp-1908.mail.infomaniak.ch [185.125.25.8]) (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 9102F13B299 for ; Mon, 29 Apr 2024 19:19:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.125.25.8 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714418363; cv=none; b=ejmFj2iyWWszGChFvqGEb1e44AfeYFgR4PMIWDymS632hX1urGmWoAh9YhRXPU3O8Nie33spSfnMERV7e6GxGUH/fLmCbHyf3K7eYqsxBpdO6Fuq3KhQGvuIVy25xLAUboBEndevk+Psuo5eAU9c2MYp77s6zZwsTINHaeRDlbY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714418363; c=relaxed/simple; bh=3DxANGGAo/N/R2VCEciaDgwx1jRJ+/NZcQBR2yba4ps=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=SldGyuHMJ7M1GlmZpZqSCK5SpaItpYLMvWEhCcJw/aCD5ETu+TR7KYylp4SgJ4NpECsxGwDBB3+Dgnd0sBoPaa7RQvVN9uWuvRj+jIU93mYgWpQleJvQw19nEXvsp2jIagqZcpSKS5sM2gW+Sw+0P9Mx69zPvsn6hSwYW1gk5gM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net; spf=pass smtp.mailfrom=digikod.net; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b=STN+6UbF; arc=none smtp.client-ip=185.125.25.8 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=digikod.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b="STN+6UbF" Received: from smtp-3-0001.mail.infomaniak.ch (smtp-3-0001.mail.infomaniak.ch [10.4.36.108]) by smtp-3-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4VStRp26zCzSLR; Mon, 29 Apr 2024 21:19:18 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=digikod.net; s=20191114; t=1714418358; bh=3DxANGGAo/N/R2VCEciaDgwx1jRJ+/NZcQBR2yba4ps=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=STN+6UbFseZfjTMTHo1ZOVIoY1lOBPhEcKfBPLVypSopbDl2Mkute9BHrJn9x6MFR HWWAH9VfWMNw2pI3a/veoNbFCMvPP/ZX+qp47tTV8YOXl3+PvexjJTjpiA0MHjLbkM +q6f6SEa06Aqy4NVD4Jmne/VO+QVPb1soM6Jhw+Q= Received: from unknown by smtp-3-0001.mail.infomaniak.ch (Postfix) with ESMTPA id 4VStRn5FjqzYnM; Mon, 29 Apr 2024 21:19:17 +0200 (CEST) From: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= To: Christian Brauner , Jakub Kicinski , Kees Cook , Mark Brown , Shengyu Li , Shuah Khan Cc: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , "David S . Miller" , =?utf-8?q?G=C3=BCnther_Noack?= , Will Drewry , kernel test robot , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH v3 4/9] selftests/harness: Fix interleaved scheduling leading to race conditions Date: Mon, 29 Apr 2024 21:19:06 +0200 Message-ID: <20240429191911.2552580-5-mic@digikod.net> In-Reply-To: <20240429191911.2552580-1-mic@digikod.net> References: <20240429191911.2552580-1-mic@digikod.net> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Infomaniak-Routing: alpha Fix a race condition when running several FIXTURE_TEARDOWN() managing the same resource. This fixes a race condition in the Landlock file system tests when creating or unmounting the same directory. Using clone3() with CLONE_VFORK guarantees that the child and grandchild test processes are sequentially scheduled. This is implemented with a new clone3_vfork() helper replacing the fork() call. This avoids triggering this error in __wait_for_test(): Test ended in some other way [127] Cc: Christian Brauner Cc: David S. Miller Cc: Günther Noack Cc: Jakub Kicinski Cc: Mark Brown Cc: Shuah Khan Cc: Will Drewry Fixes: 41cca0542d7c ("selftests/harness: Fix TEST_F()'s vfork handling") Reviewed-by: Kees Cook Signed-off-by: Mickaël Salaün Link: https://lore.kernel.org/r/20240429191911.2552580-5-mic@digikod.net --- Changes since v2: * Replace __attribute__((__unused__)) with inline for clone3_vfork() (suggested by Kees and Jakub) --- tools/testing/selftests/kselftest_harness.h | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h index 55699a762c45..9d7178a71c2c 100644 --- a/tools/testing/selftests/kselftest_harness.h +++ b/tools/testing/selftests/kselftest_harness.h @@ -66,6 +66,8 @@ #include #include #include +#include +#include #include "kselftest.h" @@ -80,6 +82,17 @@ # define TH_LOG_ENABLED 1 #endif +/* Wait for the child process to end but without sharing memory mapping. */ +static inline pid_t clone3_vfork(void) +{ + struct clone_args args = { + .flags = CLONE_VFORK, + .exit_signal = SIGCHLD, + }; + + return syscall(__NR_clone3, &args, sizeof(args)); +} + /** * TH_LOG() * @@ -1183,7 +1196,7 @@ void __run_test(struct __fixture_metadata *f, fflush(stdout); fflush(stderr); - t->pid = fork(); + t->pid = clone3_vfork(); if (t->pid < 0) { ksft_print_msg("ERROR SPAWNING TEST CHILD\n"); t->exit_code = KSFT_FAIL;