linux-kernel - Re: [PATCH v9 00/53] fix CONFIG_DRM_USE_DYNAMIC

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Message-ID: <CAJfuBxyxamRhOyz8WuL+7=eJkEKSw8jnAWjyAuqU2i7gvg-rsQ@mail.gmail.com>
Date: Tue, 2 Jul 2024 16:14:01 -0600
From: jim.cromie@...il.com
To: Luis Chamberlain <mcgrof@...nel.org>
Cc: daniel.vetter@...ll.ch, tvrtko.ursulin@...ux.intel.com, 
	jani.nikula@...el.com, ville.syrjala@...ux.intel.com, jbaron@...mai.com, 
	gregkh@...uxfoundation.org, ukaszb@...omium.org, linux-kernel@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, amd-gfx@...ts.freedesktop.org, 
	intel-gvt-dev@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org, 
	linux@...musvillemoes.dk, joe@...ches.com
Subject: Re: [PATCH v9 00/53] fix CONFIG_DRM_USE_DYNAMIC_DEBUG=y

On Tue, Jul 2, 2024 at 4:01 PM Luis Chamberlain <mcgrof@...nel.org> wrote:
>
> On Tue, Jul 02, 2024 at 03:56:50PM -0600, Jim Cromie wrote:
> > This fixes dynamic-debug support for DRM.debug, added via classmaps.
> > commit bb2ff6c27bc9 (drm: Disable dynamic debug as broken)
> >
> > CONFIG_DRM_USE_DYNAMIC_DEBUG=y was marked broken because drm.debug=val
> > was applied when drm.ko was modprobed; too early for the yet-to-load
> > drivers, which thus missed the enablement.  My testing with
> > /etc/modprobe.d/ entries and modprobes with dyndbg=$querycmd options
> > obscured this omission.
> >
> > The fix is to replace invocations of DECLARE_DYNDBG_CLASSMAP with
> > DYNDBG_CLASSMAP_DEFINE for core, and DYNDBG_CLASSMAP_USE for drivers.
> > The distinction allows dyndbg to also handle the users properly.
> >
> > DRM is the only current classmaps user, and is not really using it,
> > so if you think DRM could benefit from zero-off-cost debugs based on
> > static-keys, please test.
> >
> > HISTORY
> >
> > 9/4/22  - ee879be38bc8..ace7c4bbb240 commited - classmaps-v1 dyndbg parts
> > 9/11/22 - 0406faf25fb1..16deeb8e18ca commited - classmaps-v1 drm parts
> >
> > https://lore.kernel.org/lkml/Y3XUrOGAV4I7bB3M@kroah.com/
> > greg k-h says:
> > This should go through the drm tree now.  The rest probably should also
> > go that way and not through my tree as well.
>
> Can't this just be defined as a coccinelle smpl patch? Must easier
> to read than 53 patches?
>

perhaps it could - Im not sure that would be easier to review
than a file-scoped struct declaration or reference per driver

Also, I did it hoping to solicit more Tested-by:s with drm.debug=0x1ff

Jim

>   Luis
>