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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 EAF7DC11D24 for ; Fri, 21 Feb 2020 01:34:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CCDF524656 for ; Fri, 21 Feb 2020 01:34:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729598AbgBUBe4 (ORCPT ); Thu, 20 Feb 2020 20:34:56 -0500 Received: from mail104.syd.optusnet.com.au ([211.29.132.246]:54386 "EHLO mail104.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729516AbgBUBez (ORCPT ); Thu, 20 Feb 2020 20:34:55 -0500 Received: from dread.disaster.area (pa49-195-185-106.pa.nsw.optusnet.com.au [49.195.185.106]) by mail104.syd.optusnet.com.au (Postfix) with ESMTPS id 9D2FA820B9F; Fri, 21 Feb 2020 12:34:52 +1100 (AEDT) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1j4xDP-0005DD-UK; Fri, 21 Feb 2020 12:34:51 +1100 Date: Fri, 21 Feb 2020 12:34:51 +1100 From: Dave Chinner To: ira.weiny@intel.com Cc: linux-kernel@vger.kernel.org, Alexander Viro , "Darrick J. Wong" , Dan Williams , Christoph Hellwig , "Theodore Y. Ts'o" , Jan Kara , linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH V4 02/13] fs/xfs: Clarify lockdep dependency for xfs_isilocked() Message-ID: <20200221013451.GU10776@dread.disaster.area> References: <20200221004134.30599-1-ira.weiny@intel.com> <20200221004134.30599-3-ira.weiny@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200221004134.30599-3-ira.weiny@intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=W5xGqiek c=1 sm=1 tr=0 a=bkRQb8bsQZKWSSj4M57YXw==:117 a=bkRQb8bsQZKWSSj4M57YXw==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=kj9zAlcOel0A:10 a=l697ptgUJYAA:10 a=QyXUC8HyAAAA:8 a=7-415B0cAAAA:8 a=GGKX1iC3Kp7g_2JCx8gA:9 a=CjuIK1q_8ugA:10 a=biEYGPWJfzWAr4FL6Ov7:22 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 20, 2020 at 04:41:23PM -0800, ira.weiny@intel.com wrote: > From: Ira Weiny > > xfs_isilocked() can't work fully without CONFIG_LOCKDEP. However, > making xfs_isilocked() dependant on CONFIG_LOCKDEP is not feasible > because it is used for more than the i_rwsem. Therefore a short-circuit > was provided via debug_locks. However, this caused confusion while > working through the xfs locking. > > Rather than use debug_locks as a flag specify this clearly using > IS_ENABLED(CONFIG_LOCKDEP). > > Signed-off-by: Ira Weiny > > --- > Changes from V3: > Reordered to be a "pre-cleanup" patch > > Changes from V2: > This patch is new for V3 > --- > fs/xfs/xfs_inode.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c > index c5077e6326c7..35df324875db 100644 > --- a/fs/xfs/xfs_inode.c > +++ b/fs/xfs/xfs_inode.c > @@ -364,7 +364,7 @@ xfs_isilocked( > > if (lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) { > if (!(lock_flags & XFS_IOLOCK_SHARED)) > - return !debug_locks || > + return !IS_ENABLED(CONFIG_LOCKDEP) || > lockdep_is_held_type(&VFS_I(ip)->i_rwsem, 0); This breaks expected lockdep behaviour. We need to use debug_locks here because lockdep turns off lock checking via debug_locks when lockdep encounters a locking inconsistency. We only want to know about the first locking problem, not spew cascading lock problems over and over once we already know there is a locking problem. IOWs, checking debug_locks is required here for the same reason it is used in lockdep_assert_held_{read/write}(). essentially we are open coding lockdep_assert_held_write() here because this function is only called from within ASSERT() statements and we don't want multiple WARN/BUGs being issued when this triggers.... Cheers, Dave. -- Dave Chinner david@fromorbit.com