From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ipmail05.adl6.internode.on.net ([150.101.137.143]:45988 "EHLO ipmail05.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752058AbcKXX1M (ORCPT ); Thu, 24 Nov 2016 18:27:12 -0500 Date: Fri, 25 Nov 2016 10:26:29 +1100 From: Dave Chinner Subject: Re: [PATCH 4/4] generic: test locking when setting encryption policy Message-ID: <20161124232629.GW31101@dastard> References: <1479412027-34416-1-git-send-email-ebiggers@google.com> <1479412027-34416-5-git-send-email-ebiggers@google.com> <20161120223536.GL28177@dastard> <20161121192519.GE30672@google.com> <20161121213251.GL31101@dastard> <20161121234106.GH30672@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161121234106.GH30672@google.com> Sender: fstests-owner@vger.kernel.org To: Eric Biggers Cc: fstests@vger.kernel.org, linux-ext4@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Richard Weinberger , David Gstir List-ID: On Mon, Nov 21, 2016 at 03:41:06PM -0800, Eric Biggers wrote: > On Tue, Nov 22, 2016 at 08:32:51AM +1100, Dave Chinner wrote: > > > > This means that reproducing the race condition is going to be > > machine dependent regardless of how the test is written. > > > > In cases like this for XFS, we tend towards adding a debug sysfs > > file to introduce a delay into the code that allows the race to be > > triggered reliably. The delay is only included in CONFIG_XFS_DEBUG=y > > builds, and the test is conditional on the sysfs file being present. > > > > e.g. xfs/051 uses a log recovery delay to allow us to reliably > > trigger IO errors in the middle of log recovery and hence exercise > > the IO error failure paths in the middle of recovery. This made an > > extremely unreliable reproducer into a test case that triggered > > reliably on every machine the test is run on.... > > > > Can something like this be done in this case? > > > > I'd really rather not do something like that just for this test, which is really > just testing that the kernel does inode_lock()/inode_unlock() in > fscrypt_process_policy(). It would be more worthwhile if the testing-only > kernel code would help expose many race conditions, not just this one particular > race in this particular ioctl. OK. > So if you don't want to have the C version of this test in > xfstests, I think it should just be dropped from the series. If there's no other alternative, a test written in C is better than nothing. Thanks! -Dave. -- Dave Chinner david@fromorbit.com