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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 2AA85C433DF for ; Thu, 18 Jun 2020 17:41:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 101AF20734 for ; Thu, 18 Jun 2020 17:41:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729546AbgFRRlD (ORCPT ); Thu, 18 Jun 2020 13:41:03 -0400 Received: from mx2.suse.de ([195.135.220.15]:57880 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726899AbgFRRlD (ORCPT ); Thu, 18 Jun 2020 13:41:03 -0400 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 6A05FAC51; Thu, 18 Jun 2020 17:40:59 +0000 (UTC) Date: Thu, 18 Jun 2020 19:40:59 +0200 From: Petr Mladek To: Jim Cromie Cc: jbaron@akamai.com, linux-kernel@vger.kernel.org, akpm@linuxfoundation.org, gregkh@linuxfoundation.org, linux@rasmusvillemoes.dk, Jonathan Corbet , Andrew Morton , Will Deacon , Orson Zhai , linux-doc@vger.kernel.org Subject: Re: [PATCH v3 20/21] dyndbg: add user-flag, negating-flags, and filtering on flags Message-ID: <20200618174058.GE3617@alley> References: <20200617162536.611386-1-jim.cromie@gmail.com> <20200617162536.611386-23-jim.cromie@gmail.com> <20200618161912.GD3617@alley> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200618161912.GD3617@alley> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Thu 2020-06-18 18:19:12, Petr Mladek wrote: > On Wed 2020-06-17 10:25:35, Jim Cromie wrote: > > 1. Add a user-flag [u] which works like the [pfmlt] flags, but has no > > effect on callsite behavior; it allows incremental marking of > > arbitrary sets of callsites. > > > > 2. Add [PFMLTU] flags, which negate their counterparts; P===!p etc. > > And in ddebug_read_flags(): > > current code does: [pfmltu_] -> flags > > copy it to: [PFMLTU_] -> mask > > > > also disallow both of a pair: ie no 'pP', no true & false. > > > > 3. Add filtering ops into ddebug_change(), right after all the > > callsite-property selections are complete. These filter on the > > callsite's current flagstate before applying modflags. > > > > Why ? > > > > The u-flag & filter flags > > > > The 'u' flag lets the user assemble an arbitary set of callsites. > > Then using filter flags, user can activate the 'u' callsite set. > > > > #> echo 'file foo.c +u; file bar.c +u' > control # and repeat > > #> echo 'u+p' > control > > > > Of course, you can continue to just activate your set without ever > > marking it 1st, but you could trivially add the markup as you go, then > > be able to use it as a constraint later, to undo or modify your set. > > > > #> echo 'file foo.c +up' >control > > .. monitor, debug, finish .. > > #> echo 'u-p' >control > > > > # then later resume > > #> echo 'u+p' >control > > > > # disable some cluttering messages, and remove from u-set > > #> echo 'file noisy.c function:jabber_* u-pu' >control > > > > # for doc, recollection > > grep =pu control > my-favorite-callsites > > > > Note: > > > > Your flagstate after boot is generally not all =_. -DDEBUG will arm > > compiled callsites by default, $builtinmod.dyndbg=+p bootargs can > > enable them early, and $module.dyndbg=+p bootargs will arm them when > > the module is loaded. But you could manage them with u-flags: > > > > #> echo '-t' >control # clear t-flag to use it as 2ndary markup > > #> echo 'p+ut' >control # mark the boot-enabled set of callsites > > #> echo '-p' >control # clean your dmesg -w stream > > > > ... monitor, debug .. > > #> echo 'module of_interest $qterms +pu' >control # build your set of useful debugs > > #> echo 'module of_interest $qterms UT+pu' >control # same, but dont alter ut marked set > > Does anyone requested this feature, please? > > For me, it is really hard to imagine people using these complex and hacky > steps. I think that all this is motivated by adding support for module specific groups. What about storing the group as yet another information for each message? I mean the same way as we store module name, file, line, function name. Then we could add API to define group for a given message: pr_debug_group(group_id, fmt, ...); the interface for the control file might be via new keyword "group". You could then do something like: echo module=drm group=0x3 +p >control But more importantly you should add functions that might be called when the drm.debug parameter is changes. I have already mentioned it is another reply: dd_enable_module_group(module_name, group_id); dd_disable_module_group(module_name, group_id); It will _not_ need any new flag or flag filtering. Best Regards, Petr