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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 D9FB2C2D0CE for ; Fri, 24 Jan 2020 06:02:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B27E72072C for ; Fri, 24 Jan 2020 06:02:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730124AbgAXGCN (ORCPT ); Fri, 24 Jan 2020 01:02:13 -0500 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:32949 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725817AbgAXGCN (ORCPT ); Fri, 24 Jan 2020 01:02:13 -0500 Received: from callcc.thunk.org (rrcs-67-53-201-206.west.biz.rr.com [67.53.201.206]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 00O621rd025738 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 24 Jan 2020 01:02:03 -0500 Received: by callcc.thunk.org (Postfix, from userid 15806) id 3F24A42014A; Fri, 24 Jan 2020 01:02:00 -0500 (EST) Date: Fri, 24 Jan 2020 01:02:00 -0500 From: "Theodore Y. Ts'o" To: Greg Kroah-Hartman Cc: Jason Baron , Will Deacon , linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v3] dynamic_debug: allow to work if debugfs is disabled Message-ID: <20200124060200.GG147870@mit.edu> References: <20200122074343.GA2099098@kroah.com> <20200122080352.GA15354@willie-the-truck> <20200122081205.GA2227985@kroah.com> <20200122135352.GA9458@kroah.com> <8d68b75c-05b8-b403-0a10-d17b94a73ba7@akamai.com> <20200122192940.GA88549@kroah.com> <20200122193118.GA88722@kroah.com> <20200123155340.GD147870@mit.edu> <20200123175536.GA1796501@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200123175536.GA1796501@kroah.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 23, 2020 at 06:55:36PM +0100, Greg Kroah-Hartman wrote: > > Instead of moving the control file IFF debugfs is enabled, what about > > always making it available in /proc, and marking the control file for > > dynamic_debug in debugfs as deprecated? It would seem to me that this > > would cause less confusion in the future.... > > Why deprecate it? It's fine where it is, and most developer's have > debugfs enabled so all is good. I'd rather only use /proc as a > last-resort. This makes life difficult for scripts that manipulate the control file, since they now need to check two different locations -- either /sys/kernel/debug or /proc. It's likely that people who normally use distribution kernels where debugfs is disabled will have scripts which are hard-coded to look in /proc, and then when they build a kernel with debugfs enabled, the /proc entry will go **poof**, and their script will break. So regardless of what we do with the control file in debugfs, it might be nice if moving forward, scripts can count on the /proc file existing. Cheers, - Ted