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 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 30F6EC369AB for ; Tue, 15 Apr 2025 10:06:49 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C905D10E6EB; Tue, 15 Apr 2025 10:06:48 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=bootlin.com header.i=@bootlin.com header.b="LWa03Lgb"; dkim-atps=neutral Received: from relay5-d.mail.gandi.net (relay5-d.mail.gandi.net [217.70.183.197]) by gabe.freedesktop.org (Postfix) with ESMTPS id 45CF610E6EB; Tue, 15 Apr 2025 10:06:47 +0000 (UTC) Received: by mail.gandi.net (Postfix) with ESMTPSA id 4F6F2439F5; Tue, 15 Apr 2025 10:06:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1744711606; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=JTcEJokCnQRkRvD85b3lXKMpxaknoI3Zivb4ARRNh38=; b=LWa03LgbjYPHHPl92b6S+Yt2SFiiIN3uupq7ruRUtjY1g1SLgu2l8sDvDffRsrxOkq6PLa jFMMcF34L5vET93aEB+f/M0pFjZLQoGu0AQjWk4A0BK0lSwZY/e815tVlkk8yUthfTbzBj fuP5MOUE1O5daDosDWiRLVNSJw042X1D+gQW6j7okjxTnWh+8NbXCy5lRfPFFLSFSM5CJB LTPDq90FZ+xDinkFgjNV1Nt6BB5zj/AAp0rWZ/fIXlo3ZOPzTeK/W8c7EOH/RJEeDg8Jtw cQV2ZZ5sE/1K04voPUaa5o6TGknM6cbbfK9JnzjCaL5v2cx//Wm54IBXzQC2YA== Message-ID: <84e37f6f-47f7-481f-96eb-11b8dd79b3df@bootlin.com> Date: Tue, 15 Apr 2025 12:06:44 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Louis Chauvet Subject: Re: [PATCH v3 27/54] dyndbg: drop "protection" of class'd pr_debugs from legacy queries To: Jim Cromie , jbaron@akamai.com, gregkh@linuxfoundation.org, ukaszb@chromium.org, linux-kernel@vger.kernel.org Cc: dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, intel-gvt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, daniel.vetter@ffwll.ch, tvrtko.ursulin@linux.intel.com, jani.nikula@intel.com, ville.syrjala@linux.intel.com References: <20250402174156.1246171-1-jim.cromie@gmail.com> <20250402174156.1246171-28-jim.cromie@gmail.com> Content-Language: en-US Autocrypt: addr=louis.chauvet@bootlin.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgddvvdefudelucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuifetpfffkfdpucggtfgfnhhsuhgsshgtrhhisggvnecuuegrihhlohhuthemuceftddunecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefkffggfgfhuffvvehfjggtgfesthekredttddvjeenucfhrhhomhepnfhouhhishcuvehhrghuvhgvthcuoehlohhuihhsrdgthhgruhhvvghtsegsohhothhlihhnrdgtohhmqeenucggtffrrghtthgvrhhnpeetfffhtdeigfehffduuedvkeefgfdvuddugfffteetffdvteffgfejvedugffgffenucffohhmrghinhepsghoohhtlhhinhdrtghomhenucfkphepledtrdekledrudeifedruddvjeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpeeltddrkeelrdduieefrdduvdejpdhhvghloheplgduledvrdduieekrddtrddvtdgnpdhmrghilhhfrhhomheplhhouhhishdrtghhrghuvhgvthessghoohhtlhhinhdrtghomhdpnhgspghrtghpthhtohepudefpdhrtghpthhtohepjhhimhdrtghrohhmihgvsehgmhgrihhlrdgtohhmpdhrtghpthhtohepjhgsrghrohhnsegrkhgrmhgrihdrtghomhdprhgtphhtthhopehgrhgvghhkhheslhhinhhugihfohhunhgurghtihhonhdrohhrghdprhgtphhtthhopehukhgrshiisgestghhrhhomhhiuhhmrdhorhhgpdhrtghpthhtoheplhhin hhugidqkhgvrhhnvghlsehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtohepughrihdquggvvhgvlheslhhishhtshdrfhhrvggvuggvshhkthhophdrohhrghdprhgtphhtthhopegrmhguqdhgfhigsehlihhsthhsrdhfrhgvvgguvghskhhtohhprdhorhhgpdhrtghpthhtohepihhnthgvlhdqghhvthdquggvvheslhhishhtshdrfhhrvggvuggvshhkthhophdrohhrgh X-GND-Sasl: louis.chauvet@bootlin.com X-BeenThere: amd-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: amd-gfx-bounces@lists.freedesktop.org Sender: "amd-gfx" Le 02/04/2025 à 19:41, Jim Cromie a écrit : > Current classmap code protects class'd pr_debugs from unintended > changes by "legacy" unclassed queries: > > # this doesn't disable all of DRM_UT_* categories > echo "-p" > /proc/dynamic_debug/control > > # name the class to change it - protective but tedious > echo "class DRM_UT_CORE +p" > /proc/dynamic_debug/control > > # or do it the (old school) subsystem way > echo 1 > /sys/module/drm/parameters/debug > > This "name the class to change it" behavior gave a modicum of > protection to classmap users (ie DRM) so their debug settings aren't > trivially and unintentionally altered underneath them. > > And by "symmetry", if they're not picked by "class FOO", then they're > excluded from adjustment. This allowed all previously conceived > queries to work the way they always had; ie select the same set of > pr_debugs, despite the inclusion of whole new classes of pr_debugs. > > That had 2 downsides: > > 1. "name the class to change it" means that every class must be > individually modified, quickly becoming long-winded and tedious to > adjust all the classes in a map via >control. > > 2. It made the class keyword special in some sense; the other keywords > skip only on explicit mismatch, otherwise the code falls thru to > adjust the pr-debug site. > > So this patch reverts to the traditional view, it drops protection of > classes from default/legacy queries. > > But it also refactors the skip/continue choice to allow the module > defining the classmap to protect its classes from unintended > alterations by legacy/class-less queries. > > Next: > > Author choice: use of DYNAMIC_DEBUG_CLASSMAP_PARAM() means they want > the drm.debug style control point. We should presume they want it to > reflect whats set underneath, with only "class FOO" qualified queries > changing the callsites beneath. This explanation is way better, thanks a lot! It is way easier to understand this protection. I continue to think that this "protect its classes from unintended alterations" is not a good user api. But it is not a blocking point for me, so I would like to get the point of view from other people (mainly from DRM, they are the first users). With or without this modification: Acked-by: Louis Chauvet > CC: jbaron@akamai.com > Signed-off-by: Jim Cromie > -- > v3- s/slctd_/selected_/ > pitch the PARAM control of protection. > --- > lib/dynamic_debug.c | 31 +++++++++++++++++++++++-------- > 1 file changed, 23 insertions(+), 8 deletions(-) > > diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c > index 7a60088a1b5c..54f462cf41b0 100644 > --- a/lib/dynamic_debug.c > +++ b/lib/dynamic_debug.c > @@ -197,6 +197,17 @@ ddebug_find_valid_class(struct _ddebug_info const *di, const char *query_class, > return NULL; > } > > +/* > + * classmaps-v1 protected classes from changes by legacy commands > + * (those selecting _DPRINTK_CLASS_DFLT by omission), v2 undoes that > + * special treatment. State so explicitly. Later we could give > + * modules the choice to protect their classes or to keep v2 behavior. > + */ > +static inline bool ddebug_client_module_protects_classes(const struct ddebug_table *dt) > +{ > + return false; > +} > + > /* > * Search the tables for _ddebug's which match the given `query' and > * apply the `flags' and `mask' to them. Returns number of matching > @@ -211,7 +222,7 @@ static int ddebug_change(const struct ddebug_query *query, struct flag_settings > unsigned int nfound = 0; > struct flagsbuf fbuf, nbuf; > struct _ddebug_class_map *map = NULL; > - int valid_class; > + int selected_class; > > /* search for matching ddebugs */ > mutex_lock(&ddebug_lock); > @@ -224,21 +235,25 @@ static int ddebug_change(const struct ddebug_query *query, struct flag_settings > > if (query->class_string) { > map = ddebug_find_valid_class(&dt->info, query->class_string, > - &valid_class); > + &selected_class); > if (!map) > continue; > } else { > - /* constrain query, do not touch class'd callsites */ > - valid_class = _DPRINTK_CLASS_DFLT; > + selected_class = _DPRINTK_CLASS_DFLT; > } > > for (i = 0; i < dt->info.descs.len; i++) { > struct _ddebug *dp = &dt->info.descs.start[i]; > > - /* match site against query-class */ > - if (dp->class_id != valid_class) > - continue; > - > + if (dp->class_id != selected_class) { > + if (query->class_string) > + /* site.class != given class */ > + continue; > + /* legacy query, class'd site */ > + else if (ddebug_client_module_protects_classes(dt)) > + continue; > + /* allow change on class'd pr_debug */ > + } > /* match against the source filename */ > if (query->filename && > !match_wildcard(query->filename, dp->filename) && -- Louis Chauvet, Bootlin Embedded Linux and Kernel engineering https://bootlin.com